An innovative course in undergraduate neuroscience. Experiment in problem-based learning with 'problem boxes'. A novel course in undergraduate neurosciences is described in this paper. The course features a 'problem-box' and use of an educational prescription, each designed to foster the continual development of problem solving and self-directed study skills. The use of a wide range of evaluation tools, stimulated patients, questionnaires, tutorial evaluations, and interviews indicated that it was successful in its attempt. The philosophy of the design of problem-boxes and the problem-solving approach are discussed.


A medical sociology course in a revised curriculum. This article describes some of the factors that have been involved in the development of a medical sociology course in a revised undergraduate curriculum in the University of Dundee. The course content and the educational techniques used are discussed. The aim of the course is to give a sociological perspective on medicine which it is hoped will be of value to medical students whatever their future careers may be.


Feedback research in postgraduates on efficacy of education in school of medicine. At the Medical School, Tirgu-Mures/Romania, in the Alumni Office of the Department of Social Medicine, two feed-back researches were performed in 1962 and 1973 on 100 graduates working in basic medical care, in order to evaluate the efficacy of practical medical training. Between 1962 and 1973 efforts have been made to bring the medical teaching nearer to the ambulatory practical training. The compulsory externship (4 to 6 years), the young students' work as nurses at the patients' beds (1 to 2 years), their distribution in rural factory surgeries (5 to 6 years), the night duties at medical emergency services (6 years), as well as their training in prophylactic medico-hygiene activities brought a lot of improvements to the practical training of the students, future general practitioners. However, there are problems in this field of hygiene and epidemiology, as well as in emergency assistance. The improvement of practical education goes on. The next feed-back research is planned for 1976.


Medical students' retention of knowledge of physics and chemistry on entry to a course in physiology. In this paper we have assessed the extent to which two cohorts of medical students retained skills acquired in two of their basic science courses, i.e. physics and chemistry. It has been shown that a great deal of attrition takes place with respect to factual information and also, therefore, the capacity to apply this information in a relevant manner. It has been argued that this occurs, in part, because students do not appear to regard chemistry and physics as a useful part of their preparation as doctors and, in part, because of the methods used to teach these basic science subjects. Finally, some implications of this preliminary study have been discussed.


Recall and retrieval of anatomical knowledge. The performance outcomes of a course in anatomy based on the use of specific behavioural objectives and group discussion techniques have been followed up over a period of 21 months. At the end of this time attrition of knowledge averaged 17-5% of the original performance. 72% of students still performed at better than pass level. Performance levels on retest were significantly associated with original levels of performance and were significantly better in respect of items 'reinforced' by subsequent teaching in other subjects. It is suggested that the performance on retest also reflected the nature of the original course, which was dependent on the use of general and specific behavioural objectives and on active learning methods using group discussion techniques.


Reasons for differential performance in multiple choice and essay tests. 1. Previous studies with preclinical students demonstrated that there were factors other than topic content which produced significant differences in performance in multiple choice (MC) and essay (E) tests. 2. In this study second year medical students completed a battery of psychometric tests measuring both cognitive and non-cognitive personality traits. 3. The scores obtained after factor analyses of these tests were used as predictors of the difference in performance in 6 matched pairs of MC and E achievement tests over 2 years. 4. Students with high scores in a factor associated with introversion achieved better results in MC tests than would have been expected from their performance in E tests. On the other hand, students whose first language was not English did not perform as well in MC as they did in E tests. 5. Students with high scores in a factor associated with emotional maturity and illegible writing performed better in E tests than would have been expected from their MC results.


Multiple choice questions. The debate goes on. The clinical comprehensive examination given to Pahlavi University medical students in their last year was designed to include three types of questions: multiple choice questions (MCQ's) testing factual recall, MCQ's measuring clinical problems solving ability, and simulated patient management problems (PMP's). The scores of the three types of questions were compared with the five-year cumulative class standing and with each other. It was found that the class standing was very highly correlated with MCQ's testing for recall of information. The relation progressively lessened with problem solving MCQ's and PMP's. In the extremes of class standing there was no significant correlation with problem solving MCQ's and a significant but negative correlation with PMP's. Similar results were obtained when recall type MCQ's were compared with problem solving MCQ's and PMP's. It is concluded that the various determinants of class standing (MCQ's, oral exams, 'performance' reports, etc) are probably based on ability for factual recall and that the usual variety of MCQ's are a poor discriminating index of medical competence. It is, however, possible to write MCQ's that are better able to measure the more significant objectives of medical education.


Computerization of a patient management problems examination to prevent 'retracing'. During 1973, a 10-patient, linear PMP examination was administered in both written and computerized form to 104 candidates for certification by the American Board of Pediatrics and to 122 individuals in their first month of graduate training in paediatrics. Both groups made significantly more errors of omission (failure to select appropriate actions) and fewer correct diagnoses on the computerized version of the test than on the written version. These results suggest that examinees 'retrace' (use clues from problems near the end of the case to make additional correct decisions on earlier problems) when the test is presented in written form and that computerization prevents this phenomenon. Additional analyses indicated that the reliability of the PMP examination was essentially the same for the written and computerized versions, that both forms distinguished about equally well between first-year residents and candidates, and that both forms had about the same magnitude of correlation with the American Board of Pediatrics oral examination. Finally, correlation between both PMP forms and the American Board of Pediatrics multiple-choice examination suggested that the PMP, in either mode of presentation, measures characteristics that are not tapped by the multiple-choice test. Thus, computerization of the PMP provides a means for controlling a variable (retracing) which may be considered extraneous to the desired measurement, but it does not appear to alter the reliability of the test or to modify its relations with other measures.


Difficulties in postgraduate training of foreign paediatric residents and interns in child psychiatry. In a new program of teaching and consultation in child psychiatry for paediatric interns and residents, many of them of foreign birth, several approaches were tried: individual case consultation; screening conferences; experiential groups; didactic sessions. None succeeded very well. As a result of this experience, however, we have been able to identify some of the problems of the foreign students (and our own), which made the more usual educational approaches ineffective with them, and to determine better approaches. Some of the students had personal problems of adjustment, most were relatively unfamiliar with the culture, others could not communicat adequately and had scant psychiatric knowledge, and almost all were accustomed to an entirely different student-teacher relation. The most effective way of dealing with these problems was found to be through one-to-one supervision and consultation. Didactic sessions were changed to focus on specific ways to handle specific problems, with only simple, not very theoretical reading material used. With the growth of personal relations, informal consultation and teaching increased, and the formal programme became more successful.


Role of Canadian family medicine teacher in continuing medical education. This article is an attempt to illustrate diagrammatically and analyse the continuing medical education needs of the family physician throughout his entire career. It goes on to suggest how these needs may be met and puts forward the theory of the 'expanded university' which would include practising physicians in the community as members of faculty. This would encourage an osmotic-like interchange of students, full-time faculty, and practising physicians.


Textbooks -- a new approach.

Textbooks -- a new approach. A new approach to medical textbooks has been applied by a team comprising a publisher, educationalist, and subject specialist. The binding of the book can be opened so that additional material can be added and the pages rearranged. Illustrations are printed on separate sheets so as to be available for study at any point in the text. An interdisciplinary approach has been adopted throughout and each section of the book examines the subject from a different viewpoint, for example, a disease, a clinical presentation, or an approach to therapy. An important feature is the separation of core material from additional material. Layout and design have been used to facilitate learning and to make possible the use of the book for reference and revision.


A foreign body in the rectum presenting as a vulval abscess. A case report. A case of trans-rectal impaction of a foreign body in the perineum is reported. The importance of rectal palpation during pelvic examination is re-emphasized.


The influence of abnormal glucose tolerance (hyperglycaemia and hypoglycaemia) on pregnancy outcome when oestriol excretion is subnormal. Subnormal urinary oestriol excretion was present in 611 (13.9 per cent) of 4403 consecutive patients in whom a glucose tolerance test had been performed and urinary oestriol excretion measured during the third trimester of pregnancy. Hypoglycaemia (less than 5th centile) had a significant association with subnormal oestriol excretion. The perinatal mortality rate was significantly higher in the presence of abnormal glucose tolerance when oestriol excretion was low. Normoglycaemia was associated with a perinatal mortality rate of 1.7 per cent when oestriol excretion was persistently low, whereas in the presence of hyperglycaemia (greater than 95th centile) the perinatal mortality rate was 12.5 per cent (P less than 0.01) and when there was hypoglycaemia the rate was 14.8 per cent (P less than 0.001). Small-fordates babies occurred in 46.3 per cent of pregnancies complicated by hypoglycaemia and persistently subnormal urinary oestriol excretion. The advantage of routine urinary oestriol assay and glucose tolerance testing in pregnancy is emphasized.


Progression in response patterns of fetal heart rate throughout labour. A study of 70 fetal heart rate (FHR) traces throughout labour has allowed analysis of FHR responses associated with approximately 7000 individual uterine contractions. The significance of the less emphasized FHR patterns has been assessed and an attempt has been made to identify any trend or progression in the occurrence of these patterns. Transient acceleration was the most frequently occurring response in early labour and was the first observed response in the majority of cases. Decelerations became prevalent as labour progressed. A hypothesis is proposed to explain the observed overall progression in FHR responses and the possible physiological mechanisms underlying the cyclic changes in response patterns which occur throughout the course of labour.


Circulating levels of fibrin/fibrinogen degradation fragment E in normal pregnancy, and in association with intrauterine growth retardation and perinatal asphyxia. Levels of fibrin/fibrinogen degradation products have been measured by aspecific and sensitive radioimmunoassay for degradation fragment E (FgE) in pregnant patients. Maternal FgE levels rose from the 16th week reaching a plateau at the 36th week in normal pregnancy. There was no correlation between maternal FgE levels and maternal age, parity or the occurrence of perinatal asphyxia. A minority of patients (5 per cent) with evidence of intrauterine growth retardation showed prolonged elevation of FgE levels.


Smoking, human placental lactogen and birth weight. Human placental lactogen (HPL) was measured in 525 serum samples from 144 pregnant women and related to smoking habits and the birth weight of their infants. Women smoking during pregnancy were found to have a level of HPL significantly lower than the non-smokers (p less than 0.05). A significant correlation between HPL and birth weight was found (r=0.38); p less than 0.001) which remained significant when smoking was held constant (r=0.35; p less than 0.001). There was no relationship between birth weight and smoking when HPL was held constant.


The effects of stilboestrol and quinestrol upon coagulation and fibrinolysis during the puerperium. Two oestrogens, stilboestrol and quinestrol, were used to inhibit lactation and their effects upon coagulation and fibrinolysis were compared with control patients before delivery, during the puerperium and six weeks after delivery. During the first week of the puerperium, stilboestrol therapy was associated with rises of factors IX and X and quinestrol therapy with rises of factors IX and II. Six weeks after delivery, the clotting factors were similar to the control values in those who had received stilboestrol but factor II was still raised in the quinestrol treated patients. Additionally, a significant rise of factor X in the quinestrol group was noted at this time. Plasma antithrombin levels rose during the first week of the puerperium in all three groups but, six weeks after delivery, they were lower in those who had received oestrogens. Stilboestrol and quinestrol were also associated with a rise of plasminogen and antiplasmin concentration during the first week of the puerperium. Six weeks after delivery, quinestrol treated patients still had raised levels of plasminogen and antiplasmin while the stilboestrol treated patients only had raised levels of antiplasmin. These changes in coagulation and fibrinolysis are similar to those reported during oral contraceptive therapy. The persisting changes six weeks after delivery in women who had taken quinestrol might indicate an increased thrombogenic risk when long acting oestrogen preparations are used to inhibit lactation.


Cortisol metabolism after oral contraceptives: total plasma cortisol and the free cortisol index. Plasma concentrations of cortisol, cortisol resin uptake ratio (cortisol RUR) and free cortisol index (FCI) were measured in women taking combined oestrogen/progestogen and progestogen only oral contraceptives. Compared to control subjects, women taking the combined pill had elevated cortisol and cortisol RUR values in both the morning and afternoon but there was no significant change in FCI. Women taking the progestogen only pill had essentially normal levels of cortisol, cortisol RUR and FCI at both times of the day. As far as could be judged, diurnal variation of total cortisol and FCI remained unimpaired in women taking both types of pill. The FCI measurements indicated that there was no significant increase in metabolically active cortisol in women taking either the combined oestrogen/progestogen or the progestogen only type of oral contraceptive.


Serum immunoglobulins and C-reactive protein in patients using intrauterine contraceptive devices. Serum IgA, IgG, IgM and C-reactive protein levels were measured over a 12-week period in 20 women using the intrauterine contraceptive device. No significant amount of serum C-reactive protein was detected at any time. Alterations in the serum immunoglobulin levels are discussed.


Endometrial granulocytes in proliferative endometrium. Endometrial granulocytes were found in significant numbers in proliferative, hyperplastic and carcinomatous endometrium. The significance of this observation is discussed.


A large hamartoma (angioleiomyolipoma) arising from the uterine cervix. A pelvic mass removed from an asymptomatic 52-year-old woman proved to be a large angioleiomyolipoma arising from the cervix and lying within the broad ligament. It was histologically unusual in that it incorporated structures reproducing the sinuses of lymph nodes.


Sclero-cornea and defective mesodermal migration. A 5-month-old boy with bilateral sclero-cornea, multiple systemic abnormalities, and normal karyotype had his left eye removed after corneal perforation. Histopathological examination of the enucleated eye revealed an irregular corneal epithelium, absent Bowman's membrane, thickened and vascularized stromal lamellae, absent Descemet's membrane and endothelium, no angle structures, hypoplasia of the iris and ciliary body, and total kerato-iridic adhesions. A profound defect in embryogenesis due to defective mesodermal migration during the earliest phase of mesoderm differentiation is postulated as the causative factor in this case.


Early breakdown of the blood-retinal barrier in diabetes. The blood-retinal barrier plays an important part in the processes of retinal pathophysiology. A new clinical method for the study of the blood-retinal barrier by vitreous fluorophotometry appears to satisfy the necessary requirements in that it is quantitative and shows good reproducibility and high sensitivity. The application of this method  to a series of diabetic patients with apparently "normal" fundi revealed the presence of a significant breakdown of the blood-retinal barrier in the early stages of retinal involvement in diabetes. The extent of the breakdown can be measured allowing for comparative and evolutionary evaluations. The disturbance of the blood-retinal barrier, as evidence by vitreous fluorophotometry, appears before microaneurysms or capillary closure can be demonstrated by fluorescein angiography.


Neuro-ophthalmic sarcoidosis.

Neuro-ophthalmic sarcoidosis. Sarcoidosis is a multisystem disorder in which ocular involvement occurs in about one-quarter and neurosarcoidosis in 7 per cent of patients. When the retina is involved, the reported incidence of central nervous system sarcoidosis is 37 per cent. The patient described had a transient papular eruption of the legs, bilateral hilar lymphadenopathy, polyarthralgia with knee effusions, and bilateral facial and peripheral neuropathy. Ocular involvement was characterized by anterior uveitis (in the initial stages), vitreous flare, bilateral disc oedema, macular oedema, streak haemorrhages, peripheral periphlebitis, nerve fibre bundle defects, and candle-wax spots. Fluorescein angiography showed no fluorescence of the candle-wax spots nor of the adjacent vessels. However, there was hyperfluorescence of two retinal lesions. This patient had unilateral internal ophthalmoplegia, only three cases of which have been reported in the literature. Her health was restored by heavy, prolonged corticosteroid therapy. Her family history revealed that an uncle died of sarcoidosis complicated by cryptococcal meningitis. The literature on retinopathy in sarcoidosis is reviewed and the lesions noted in the posterior segment are listed.


Fluorescein angiography in carotid ischaemia. A cheap and safe screening method for demonstrating ocular ischaemia using fluorescein angiography is described and illustrated.


Effect of benzalkonium chloride on the stability of the precorneal tear film in rabbit and man. Benzalkonium chloride, a surface-active preservative commonly used in eyedrop preparations, has been shown to hasten the drying of the precorneal tear film. In the rabbit, 0.01 per cent benzalkonium (the concentration usually employed as a preservative) shortened the time required for the appearance of dry spots on the corneal surface by a factor of about four. In man, an approximately twofold hastening was demonstrated. This effect is thought to preclude the use of this substance as a preservative in eyedrop preparations for use as local anaesthetics.


Acute presumed histoplasmosis of the optic nerve head. A 38-year-old man from the Ohio Valley area presented to the Ophthalmology Cinic at a west coast hospital (USA) because of sudden loss of the right inferior temporal visual field after severe right frontal headache of several hours' duration. During the following months, diffuse peripapillary atrophy and peripheral punched-out lesions developed. When he had been seen initially, the fundus of the left eye had also revealed extensive, diffuse, peripapillary atrophy and scarring. All laboratory tests were normal except a histoplasmin intradermal skin test. The clinical appearance of both eyes 8 months after the acute episode in the right eye supports the diagnosis of presumed ocular histoplasmosis.


Drusen of the optic disc. A retrospective study in cadaver eyes. A retrospective study of 737 consecutive necropsies yielded 15 cases of drusen of the optic nerve head, an incidence of 20-4 cases per thousand. This represents the highest incidence yet reported. The histopathological features of drusen of the nerve head included elevation of the nerve head, compression of optic nerve fibres, partial optic atrophy, cytoid bodies, disc haemorrhages, juxtapapillary retinal scarring with haemosiderin deposition, calcification, and iron deposition within drusen.


Trachoma in the Sudan. A laboratory study. Out of 46 patients in the Sudan who had been diagnosed clinically as having trachoma 25 strains of the trachoma agent were isolated. Bacterial contamination was easily controlled by streptomycin and vancomycin. On repeated passaging, chick embryos lost their susceptibility to the trachoma agent during the summer.


Incidence of aphakic macular oedema. A prospective study. A prospective angiographic study of 77 aphakic eyes demonstrated cystoid macular oedema in 36 eyes (46-7 per cent) 6 to 7 weeks postoperatively. This subsequently resolved in 16 eyes, improved in eight, and was no better or worse in five (eight patients failed to return for follow-up). Of those patients with cystoid oedema, 16-6 per cent had a visual acuity of less than 6/12 at the time of the original examination; this was reduced to 13-8 per cent at the time of the follow-up study. The mean visual acuity of the group with oedema improved from 6/9 to 6/7-5 between the two examinations compared with 6/6 in the remaining 53-3 per cent without oedema. Preoperative ocular or general disease, specific surgical technique, and vitreous loss were not shown to be associated with macular oedema. However, there was some indication that intraocular inflammation predisposed to macular oedema.


Posterior vitreous detachment after cataract extraction in non-myopic eyes and the resulting retinal lesions. A series of 54 non-myopic aphakic eyes with no signs of posterior vitreous detachment and 63 non-myopic aphakic eyes with various stages of posterior vitreous detachment was followed-up for a period of 6 months to 6 years. Over half of the eyes with no vitreous detachment when first examined developed various stages of posterior vitreous detachment during the follow-up period; in 10 eyes this was accompanied by entopsies with or without photopsies and three eyes developed five new retinal tears. In over half of the eyes with partial vitreous detachment when first examined, the vitreous detachment continued to progress causing retinal detachment in one eye. Late vitreous detachment in non-myopic aphakia or the completion of a partially-detached vitreous could account for the higher incidence of retinal tears in this group of eyes.


Pilocarpine dispensation for the soft hydrophilic contact lens. The use of hydrophilic soft contact lenses for dispensation of pilocarpine is described. The release rate of pilocarpine from three materials of different water content was estimated and from this the surface concentrations were calculated. It is estimated that PolyHEMA can after 15 hours provide a 1 per cent surface concentration of pilocarpine, whereas higher water content materials (70 and 85 per cent) halve this, although they provide a much higher concentration in the first few hours of use. These results are based upon pre-soaking in 4 per cent pilocarpine solution. Because contact lenses present a management problem, this method of dispensation will be used only for selected cases. Some clinical examples treated successfully over a 20 month period are discussed.


Dark-without-pressure fundus lesions.

Dark-without-pressure fundus lesions. Seven black patients had dark brown homogeneous geographical areas of the fundus. Six cases were associated with sickle cell haemoglobinopathies and one was associated with systemic hypertension. These flat lesions were uniform in colour and occurred in the posterior pole or in the midperiphery. They appeared to be transient and often disappeared leaving no residue. The cause is unknown. By analogy with white-without-pressure fundus lesions, we have called these areas dark-without-pressure.


Myopia-aphakia. I. Prevalence of retinal detachment. Retinal detachment after cataract extraction occurred in nine out of 136 eyes with myopia of 6 or more dioptress (6-7 per cent), during a follow-up period of 1 1/2-9 1/2 years. Five of the nine detachments occurred within 3 months of cataract extraction. All patients with retinal detachment were under the age of 63 years. Relatively young patients with high myopia bear a special risk of developing retinal detachment after lens extraction. The possible reason for this is discussed.


Myopia-aphakia. II. Vitreous and peripheral retina. Biomicroscopical examination of the vitreous and peripheral retina was performed on 103 aphakic eyes with myopia of at least -6-0 dioptres. Retinal breaks were found in 19 eyes (18-4 per cent). Posterior vitreous detachment was present in all but one of the eyes. The high prevalence of retinal breaks in aphakic eyes with high myopia is compatible with the high incidence of retinal detachment in such eyes.


Cilio-retinal arterial circulation in central retinal vein occlusion. The hypothesis that an occlusion of the central retinal artery is an essential prerequisite for haemorrhage formation after central retinal vein obstruction has been investigated by examining the fundus changes in patients with a cilio-retinal arterial circulation; the findings are at variance with the 'combined occlusion hypothesis'. Comparisons were made between the pathological features in two retinal capillary beds with independent sources of arterial supply--namely, the central retinal and cilio-retinal arteries--but with an obstructed venous drainage channel common to both--namely, the central retinal vein. The importance of intraluminal pressure changes (as distinct from perfusion changes) in the causation of haemorrhages and oedema after venous occlusion is stressed, and the role of arterial disease in the pathogenesis of venous occlusions is distinguished from its role in determining the sequelae of such occlusions.


Multiple major retinal vascular occlusions in sickle cell haemoglobin C disease. A case of multiple occlusions of different sized arterioles involving the central area of the fundus has been reported in a patient suffering from sickle cell haemoglobin C disease (SC).


Complete avulsion of the optic nerve. A clinical, angiographic, and electrodiagnostic study. A case of traumatic complete avulsion of the optic nerve is reported together with fluorescein angiography and electrodiagnostic findings. Despite the disappearance of the central vessels, circulation remained in the branch retinal vessels and angiography demonstrated communication between peripapillary choroidal vessels and the superior temporal artery. The visually-evoked cortical response was abolished. Electroretinography showed a normal a-wave but reduced amplitude b-wave, not supporting the theory of the existence of centrifugal retino-suppressive fibres in the optic nerve of man.


The investigation of peptide-oligodeoxythymidylic acid interactions using template chromatography. Poly(vinyl alcohol) has been substituted with oligodeoxythymidylic acid and the resulting polyanion irreversibly attached to DEAE-cellulose via ionic bonding. Peptide-oligonucleotide interactions have been studied using a column chromatography technique with the PV(pT)n-DEAE-cellulose as stationary phase. Of all the naturally occurring amino acids, only tryptophan and to a lesser extent tyrosine intreact significantly with the immobilized oligodeoxythymidylic acid residues under the conditions for base pairing. The homopolymers of tryptophan and tyrosine undergo greater retardation than the monomers, such that the effect is not additive but multiplicative. Thus Tyr-Tyr-Tyr shows an eightfold and Trp-Trp-Trp an approximately 30-fold larger retardation than tyrosine and tryptophan, respectively. The peptide-oligonucleotide interaction decreases considerably when nonaromatic amino acids are present in the peptide. Consequently, naturally occurring peptides and proteins which contain relatively small amounts of tryptophan and tyrosine compared with the nonaromatic amino acids undergo at the most only slight retardation on the PV(pT)n-DEAE-cellulose. The retention of oligonucleotides and peptides containing these aromatic amino acids is due in both cases mainly to base stacking (roughly 67% of the total interaction) but involves different mechanisms. Thus, the peptides interact preferably with the cellulose matrix whereas the oligonucleotides with the immobilized oligonucleotides. Interaction via hydrogen-bond formation makes up the remaining 33% of the total interaction. The oligonucleotides and peptides of the mobile phase interact with each other also via this mechanism. The strength of the d(pA-A-A) interaction is roughly that of Trp-Trp whereas d(pA-A-A-A) is weaker than Trp-Trp-Trp.


Biosynthesis of the polyoxins, nucleoside peptide antibiotics: glutamate as an origin of 2-amino-2-deoxy-L-xylonic acid (polyoxamic acid). The biosynthetic origin of the carbon skeleton of 2-amino-2-deoxy-L-xylonic acid (polyoxamic acid) is described. This aminoaldonic acid is the N terminus of the nucleoside peptide antibiotics, the polyoxins, produced by Streptomyces cacaoi var. asoensis. In vivo experiments concerning incorporation and distribution of radioactivity from a number of 14C-labeled compounds have clearly shown that the carbon skeleton of glutamate is a precursor for this aminoaldonic acid and sugars are incorporated only after their conversion into gluamate through the glycolytic and the tricarboxylic acid cycle pathways. Experiments utilizing [14C]-acetate and succinate have also indicated multiple passages through the Krebs cycle are operating before their incorporation into polyoxamic acid via glutamate. The distribution of 14C between C-1 and C-5 of polyoxamic acid from [5-14C]glutamate experiment has indicated that 40% of glutamate incorporated only after the reversible conversion into alpha-ketoglutarate followed by the passage through the Krebs cycle. Lack of incorporation of 3H in the [1-14C;2-3H]- and [5-14C;2-3H]glutamate experiments is discussed in terms of a reaction(s) between glutamate and polyoxamic acid.


The mechanism of action of vinblastine. Binding of [acetyl-3H]vinblastine to embryonic chick brain tubulin and tubulin from sea urchin sperm tail outer doublet microtubules. Tritium-labeled viblastine, specific activity 107 Ci/mol, was prepared by acetylation of desacetylvinblastine with [3H]acetic anhydride, and has been employed in a study of vinblastine binding to tubulin. There are two high affinity vinblastine-binding sites per mole of embryonic chick brain tubulin (KA = 3-5 X 10(5) l./mol). Binding to these sites was rapid, and relatively independent of temperature between 37 and 0degreeC. Vincristin sulfate and desacetylvinblastine sulfate, two other active vinca alkaloid derivatives, competitively inhibited the binding of vinblastine. The inhibition constant for vincristine was 1.7 X 10(-5) M; and for desacetylvinblastine, 2 X 10(-5) M. The vinblastine binding activity of tubulin decayed upon aging, but this property was not studied in detail. Vinblastine did not depolymerize stable sea urchin sperm tail outer doublet microtubules, nor did it bind to these microtubules. However, tubulin solubilized from the B subfiber of the outer doublet microtubules possessed the two high affinity binding sites (KA = 1-3 X 105 l./mol). These data suggest that vinblastine destroys microtubules in cells primarily by inhibition of microtubule polymerization, and does not directly destroy preformed microtubules.


Fat metabolism in higher plants. Production of short- and medium-chain acyl-acyl carrier protein by spinach stroma preparations treated with cerulenin. Incubation of stroma preparations from spinach chloroplasts with low concentrations of cerulenin (10 muM) resulted in severe inhibition of fatty acid synthesis but stimulated the release of medium-chain acids in very high proportions (60-70%). Preincubation of these preparations with cerulenin in the absence of substrate exerted no additional effect on subsequent fatty acid synthesis (as measured by incorporation of [14C]acetate into fatty acids) or the pattern of radioactive acids obtained. Acyl-protein, acyl-CoA, free fatty acids and lipids were resolved from each other and analysed for their distribution of 14C-labelled fatty acids. Acyl-protein derived from cerulenin-treated preparations was the only fraction which contained short- and medium-chain acids (C6--C12). The other fractions from both control and cerulenin-treated groups consisted exclusively of C16 and C18 acids. Acyl-protein was purified by gel filtration chromatography and was characterized as acyl-acyl carrier protein.


Organ and intracellular localization of short-chain acyl-CoA synthetases in rat and guinea-pig. 1. Homogenates of rat epididymal fat pad, heart, kidney, lactating mammary gland, liver, skeletal muscle and small intestinal mucosa have been partitioned into a particulate and supernatant fraction. With reliable marker enzymes for the mitochondrial matrix and the cytosol: propionyl-CoA carboxylase and pyruvate kinase, the distributions of the acyl-CoA synthetase activities measured at 1 and 10 mM C2, C3 and C4 over mitochondria and cytosol have been calculated. From these values an estimate was made of the K0.5 of the fatty acids. 2. A distinct fatty acid-activating enzyme was assumed to be present in one of the compartments when that fatty acid was activated with a K0.5 less than or equal to 1.5 mM in an amount of greater than 13% of the total cellular activity. Adipose tissue, gut, liver and mammary gland, all organs of a high lipogenetic capacity, contained a cytosolic acetyl-CoA synthetase. At 1 mM acetate 60, 31, 77 and 83% of the total cellular activities in these organs were cytosolic in nature, with activities of 0.021, 0.32, 0.37 and 1.16 mumol C2 activated per min per g wet weight, respectively. 3. Mitochondrial acetyl-CoA and butyryl-CoA synthetases were found in adipose tissue, gut, heart, kidney, mammary gland and muscle. They were absent in liver. Adipose tissue and liver contained a mitochondrial propionyl-CoA synthetase with activities at 1 mM C3 of 0.014 and 1.50 mumol C3 activated per min per g wet weight, respectively. 4. At 1 mM, C2 was activated with decreasing rates by kidney, heart, mammary gland and gut (7.6-1.0 mumol C2 activated per min per g wet weight). C3 (1 mM) activation was about equal (1.6-1.9 mumol C3 activated per min per g wet weight) in liver, kidney and heart. C4 (1 mM) was activated with decreasing rates by heart, liver, kidney and gut (4.0-0.5 mumol C4 activated per min per g wet weight) in the order given. 5. The influence of the isolation method and the diet on fatty acid activation in small intestinal mucosal scrapings have been studied. To demonstrate the existence of cytosolic acetyl-CoA synthetase in fed animals a pre-treatment of everted intestine by low amplitude vibration has been found essential. Also C16 activation was highly (95%) decreased in a non-pre-vibrated preparation. 24 h starvation lowered cytosolic C2 and total C16 activation by 90 and 80%, respectively. Refeeding of starved rats with a balanced fat-free diet, and not with sucrose only, gave the same cytosolic C2 and total C16 activation as normally fed rats. 6. In guienea-pig heart, kidney, liver and muscle about the same partitions have been found as in the respective rat organs. The acetate activation in liver was factor 6 lower. Acetate and butyrate activation in guinea-pig muscle was much higher (6 and 37 times, respectively).


Brain lipids from the porpoise (Delphinus delphis). Phosphoglycerides rich in isovaleric acid and long-chain iso-acids. The whole brain of a porpoise (Delphinus delphis) comprised 23.1 wt% of phospholipids on a dry weight basis. Ethanolamine phosphoglycerides (36.6 wt%), choline phosphoglycerides (27.3 wt%), and serine phosphoglycerides (16.9 wt%) were the major components of the phospholipids. A unique feature of the data was the occurrence of large amounts of isovaleric acid in choline phosphoglucerides (28.1 mol%) and ethanolamine phosphoglycerides (6.4 mol%), together with 11.6 and 15.2 mol% of long-chain (C11--C16) iso-acids, respectively. Interestingly, serine phosphoglycerides did not contain detectable amounts of isovaleric acid although trace amounts of long-chain iso-acids were present. No previous evidence exists to show that appreciable amounts of a short-chain acid can be accommodated in animal phospholipids. The occurrence of isovaleric acid in the principal phosphoglycerides of the porpoise brain elicits an interest in how such an anomalous structure is accommodated in the lipid bilayers of the neural membranes.


Ether lipid metabolism. Incorporation of O-hexadecyl ethanediol into rat brain lipids. 1-O-[1'-14C]Hexadecyl ethanediol was administered intracerebrally to myelinating rat brain, and incorporation of radioactivity into brain lipids was followed over a 48-h period: (1) O-Hexadecyl ethanediol was metabolized primarily through oxidative ether bond cleavage, and much of the label was recovered in phospholipid acyl groups. (2) Substantial amounts of radioactivity were also found in choline and ethanolamine phospholipids having an O-hexadecyloxyethyl glycerol backbone. This means that alkyl ethanediol was used in glycerol ether biosynthesis as are long-chain primary alcohols. (3) Acidic hydrolysis of the ethanolamine glycerophosphatide fraction yielded also labeled hexadecanol which may indicate desaturation of 1-O-hexadecyloxyethyl 2-acyl glycerophosphoryl ethanolamine to the plasmalogen analogue. (4) Small amounts of the substrate were oxidized to O-hexadecyl glycolic acid and incorporated into the phospholipids. The substrate did not serve as precursor of O-hexadecyl ethanediol phosphorylcholine or phosphorylethanolamine in the brain.


Gangliosides of the human gastrointestinal mucosa. Gangliosides of the human alimentary mucosa were purified and analysed with thin-layer chromatography and gas chromatography. The content of ganglioside neuraminic acid was 0.16 mumol/g dry weight in the stomach, 0.07 mumol/g dry weight in the small intestine and 0.11 mumol/g dry weight in the large intestine. Mono- and disialosylhemosides were the major gangliosides, on a molar basis 68% of the total found in the stomach and 44% of the total in the small and large intestine. Considerable amounts of more complex gangliosides were found, especially in the small and large intestine, in which the molar content of tri- and tetraglycosylgangliosides containing galactosamine made up 38% of the total. Two glucosamine-containing gangliosides were also found, the probable structures of which were mono- and disialotetraglycosylceramide. The presence of the latter is reported for the first time.


Ceramides of human normal and cataractous lens. Ceramides were quantitatively isolated from human normal and cataractous lens by solvent extraction, silicic acid chromatography, thin-layer chromatography, and gas-liquid chromatography. Only two species of ceramides with normal fatty acids were detected. In the mature cataracts, there was an increase in palmitate and nervonate at the expense of the other fatty acids. Due to the increase of 24 : 1, the ratio of 24 : 1/24 : 0 increased significantly from normals to cataracts. Sphinganine was the major long-chain base, but 4-sphingenine was also present. The total amount of ceramides in the immature and mature cataracts was 1.8 and 3.0 times higher than the normals of the same age group. Such an increase does not seem to be the result of an age-dependent process.


Biosynthetic studies on mannolipids and mannoproteins of normal and vitamin A-depleted hamster livers. The incorporation of [1-14C]mannose into hamster liver glycolipids and glycoproteins was studied in normal and vitamin A-depleted hamsters. Severly (25% weight loss) and mildly (no weight loss) deficient animals were compared to vitamin A-fed controls. The incorporation of [14C]mannose into glycolipids and glycoproteins decreased in mild and severe vitamin A deficiency by 63-90% compared to vitamin A-fed animals. These results were essentially the same whether expressed per g of wet liver, per DNA or per protein. The size of the pools of mannose, glucose and galactose and their specific radioactivity in liver were determined by gas-liquid chromatography of the boronates of the hexitols (Eisenberg, Jr, F. (1972) Methods Enzymol. XXVIIIB, 168-178) in normal and vitamin A-deficient conditions. It was found that the amount of free hexoses per g of liver was very similar in normal and vitamin A-deficient conditions. The specific radioactivities for mannose and glucose were greater in vitamin A deficiency, thus excluding the possibility that the observed severe decrease in glycopeptide and glycolipid synthesis is a reflection of a similar decrease in the specific radioactivity of the precursor pools. Quantitation of mannose in glycoprotein showed a 79% decrease in vitamin A deficiency. Specific radioactivity of mannose in glycoproteins, 20 min after injection of the label, was 187 dpm/mug of mannose in the normal and 48 kpm/mug of mannose in the vitamin A-deficient livers. It is concluded that vitamin A is necessary for the biosynthesis of liver mannose-containing glycoproteins and glycolipids.


Genetic control of sterol esterification in developing wheat endosperm. 1. The action of gene Pln, previously characterized by the sterol ester patterns of mature whole wheat kernels, has been found to be restricted to the endosperm and not to affect the embryo, the pericarp or the seed coat. 2. The dominant allele Pln, which determines a sterol ester pattern with palmitate as the main ester, is also responsible for a low level of free sterol at maturity. A high level of free sterol is associated with the recessive allelet pln, which determines an ester pattern with linoleate as the main ester. 3. Divergence between the two phenotypes starts at about 21 days after anthesis, when cell proliferation has been completed, the aleurone layer has differentiated, and only cell enlargement is taking place. A marked increased in esterification, mainly by palmitate, which is controlled by the dominant allele, is concomitant with a sharp decrease in free sterol. 4. The increased net esterification is non-specific with respect to 4-demethyl sterols, because it affects the four main ones, namely sitosterol, stigmasterol, campesterol and cholesterol.


Crystallization and properties of rat liver malate dehydrogenase (decarboxylating) (NADP). Rat liver malate dehydrogenase (decarboxylating) (NADP) ((L-malate: NADP) oxidoreductase (oxaloacetate-decarboxylating), EC 1.1.1.40) was purified and crystallized from medium containing 30 mM Tris-HCl buffer (pH 7.7), 5 mM MgCl2 and 2 mM 2-mercaptoethanol. The enzyme formed rhomboid crystals free from coenzyme, and appeared homogeneous on isoelectric focusing. The crystalline enzyme had an isoelectric point of pH 6.3. Amino acid analysis showed that it contained more acidic amino acids than basic ones.


Determination of the subunit molecular weight of hypoxanthine-guanine phosphoribosyltransferase from human erythrocytes by recovery of enzyme activity from sodium dodecyl sulphate gels. The molecular weights of the subunits of the enzyme hypoxanthine-guanine phosphoribosyltransferase (EC 2.4.2.8) from human erythrocytes were determined with a simple novel method, including electrophoresis in sodium dodecyl sulphate gels, gel slicing, elution of protein from the gel slices and enzyme reactivation in the presence of the substrate 5-phosphorylribose-1-pyrophosphate. As molecular weight standards glutaraldehyde-polymerized polypeptides of human haemoglobin were used. The experiments clearly showed the existence of molecular weight differences in human erythrocyte hypoxanthine-quanine phosphoribosyltransferase.


Lack of specific correlation of the deoxycytidine triphosphate pool level with rate of DNA synthesis. The levels of the four deoxyribonucleoside triphosphate pools and the distribution of cells in the various phases of the cell cycle have been examined in Chinese hamster cells as thymidine, present as a regular constituent in the growth medium, was removed in stages. The results indicate that: 1. Duration of the DNA synthetic phase was lengthened when thymidine was removed from the growth medium. 2. Temporally correlated with lengthening of the DNA synthetic phase upon thymidine removal was a 7-fold increase in level of the dCTP pool, reduction in the dGTP pools, and little or no change in dATP pool. 3. Radioactive labeling procedures indicated that expansion of the dCTP pool could be completely accounted for by increased ribonucleotide reductase activity and that the dTTP pool switched from a largely exogenous thymidine source to endogenous dTTP synthesis as the extracellular thymidine concentration was reduced. 4. Deoxyuridine and thymidine were apparently transported by the same system in Chinese hamster cells, while deoxycytidine was transported by a different system. Although deoxycytidine transport was unaffected by thymidine, phosphorylation of intracellular deoxycytidine compounds to the triphosphate level was stimulated by thymidine. Cytidine transport was not significantly affected by thymidine.


Dissociation of the DNA replicase system of bovine lymphocyte nuclei. Exposure of S-phase nuclei or subnuclear preparations from phytohemagglutinin-stimulated bovine lymphocytes to 0.02 M ATP caused an immediate and almost total loss of their ability to replicate DNA in vitro. Other ribonucleoside and deoxyribonucleoside triphosphates caused a similar inhibition of DNA replication. Levels of ATP which inhibit replication cause the release of DNA polymerases alpha and beta and small pieces of DNA from these nuclei. This release occurs both at 4 and 37 degrees C. The data support the conclusion that high levels of ATP or other nucleoside triphosphates inhibit DNA replication in nuclei by dissolution of the DNA replication complex. The limited success in reconstitution of the DNA replicase complexes is discussed.


Physical studies on the binding of cis-dichlorodiamine platinum (II) to DNA and homopolynucleotides. The amount of cis-dichlorodiamine platinum (II) bound to DNAs of varying (dA + dT) content was assayed by both ultraviolet absorbance spectrophotometry and the use of the radioisotope 1 9 5 Pt. Radioisotope labeling indicates twice as much bound platinum as do optical measurements. The molar ratio of bound platinum r at saturation is approximately half the sum of the nearest-neighbor frequencies of all base-pairs that do not contain thymine. We therefore conclude that platinum does not bind to thymine in DNA. Chromatographic studies with (14C) purine-labeled DNA indicate preferential binding of platinum to guanine, followed by binding to adenine. The luminescence properties of DNA and of homopolynucleotides are strongly affected by bound platinum as a result of a heavy-atom effect. A plot of the fluorescence-to-phosphorescence ratio as a function of r gives a saturation binding curve similar to that obtained using 1 9 5 Pt. Ultraviolet irradiation of DNA treated with the platinum compound results in a 30% increase in the rate of formation of thymine homocyclobutadipyrimidine. When acetophenone sensitization is employed, platinum binding enhances cytosine homocyclobutadipyrimidine formation 10-fold presumably because the triplet level of cytosine complexed with platinum is lowered below that of acetophenone. The viscosity of DNA decreases sharply upon binding platinum, with half the change occuring when less that 6% of the bases are complexed. From the rate of reaction with formaldehyde, we conclude that binding of the platinum compound to DNA induces small denatured regions that unwind in the presence of formaldehyde with a rate about 40 times slower than that of a single-strand chain break.


Temperature sensitivity of protein synthesis initiation in the reticulocyte lysate system. Reduced formation of the 40 S ribosomal subunit - Met-tRNAf complex at an elevated temperature. Analysis of protein synthesis in the rabbit reticulocyte lysate system revealed the existence of a temperature-sensitive step in chain initiation which became irreversibly inactivated in the incubation at 42 degrees C. This inactivation of initiation was accompanied by a marked reduction in formation of the 40 S ribosomal subunit - Met-tRNAf complex. Decreased protein synthesis and a decrease in formation of the 40 S complex were also evident in unfortified lysates which had been prewarmed at 42 degrees C prior to protein synthesis. Hemin did not protect such lysates. The addition of supernatant fraction of a fresh lysate did not promote recovery of the reduced protein synthesis by such prewarmed lysates. Moreover, the addition of supernatant fraction prewarmed at 42 degrees C in the presence of added hemin caused little inhibition of protein synthesis by fresh lysate. The results indicate that the supernatant fraction is not involved in the inactivation.


Elongation factor 2 as the target of the reaction product between sodium selenite and glutathione (GSSeSG) in the inhibiting of amino acid incorporation in vitro. The product of the reaction between sodium selenite and glutathione, designated as selenodiglutathione (GSSeSG), nearly completely inhibits amino acid incorporation from [14C]leucyl-tRNA by free polyribosomes isolated from rat liver. The mechanism of this inhibition was studied on the basis of the following three findings. Glutathione decomposes GSSeSG  to harmless products; GSSeSG acts instantaneously on some component of the complete incubation system during preparation of the incubation vessels (at 0 degrees C); once GSSeSG has reacted its inhibitory effect cannot be reversed by glutathione. Accordingly, the effect of GSSeSG on the various steps of the amino acid incorporation process was studied by varying the sequence of additions of the reaction components, GSSeSG and GSH. The results of these and other experiments showed elongation factor 2 to be target of GSSeSG. The GSSeSG-B blocked factor could be regenerated by reduction with glutathione reductase and NADPH.


[Application of rare-earth elements as labels in studying biologically active compounds. III. Natural and magnetic circular dichroism of complexes of rare-earth elements with pyridoxalidene amino acid complexes]. Circular dichroism of pyrodoxalidenaminoacid complexes with rare earths and other metals and magnetic circular dichroism of several neodimium complexes are investigated. CD spectra of the complexes of the rare earths with azometines made of different amino acids could be classified into four groups. Some of the CD spectra are shown to be individual. The dependence of the CD spectra on the rare earch ion dimension is considered. Coordination of the rare earth ions is shown to be the same as in the case of zinc, cobalt, iron or copper.


[Instability and excitation propagation in a catalytic reaction model. II. Distributed system model]. The regime of excitation propagation in monomeric model of active medium is considered. Conditions exist when the phase plane falls into two regions in both of which the equations are linear and their automodel solutions are found analytically. After connecting the solutions a transcendental algebraic equation is obtained, from which the values of excitation propagation rate can be found. The trigger wave has one rate value the propagating impulse--two (physically realised--one). There is a parameter region with four rates (three physically realised ones).


[Temperature changes in ribonuclease].

[Temperature changes in ribonuclease]. Deuteroexchange kinetics of ribonuclease is studied by the change of IR-spectra in the range of 1400--1900 cm-1 at different temperatures in solutions with two pD values, 2.6 and 5.1. It is shown that in the pre-denaturational temperature range the enthalpy of unfolding is 1.5 kcal/mol, i. e. two orders lower than the enthalpy of unfolding in the denaturational temperature range (100--120 kcal/mol). Thus in the pre-denaturational range of temperatures the disclosure of a compact protein structure can proceed at the expense of separate non-cooperative disruptures of bonds. However, the concentration of these disruptures is so low that they cannot give an explanation to the observed pre-denaturational macroscopic changes of protein.


[Experience in the use of synchrotron radiation for the x-ray study of biopolymers]. The results of methodical work, carried out on the sources of synchrotron radiation (SR) with the aim of using SR as a powerful source of X-rays for studying biopolymer structure, are presented. The questions of monochromatization are considered. The technique designed for photoregistration of diffraction patterns within the wide range of scattering angles is described. X-ray diffraction patterns of feather ceratin, collagen and striated muscle are obtained with exposure periods ten times less than those in the case of X-ray tubes. The high resolution of diffraction lines, the absence of parasitic phone and the presence of reflections within the wide range of scattering angles are characteristic of these patterns.


[Impulse photoconductivity of solutions of ohlorophyll and its analogs. III. Photoconductivity of hexanol solutions of chlorophyll a in the presence of n-benzoquinone. Kinetic and temperature measurements]. It is shown that an increase deltasigma of electroconductivity of chlorophyll "a" (Chlalpha) solution in hexanole in the presence of n-benzoquinone (Q) under impulse illumination of solution is proportional to flash intensity: deltasigma=1(0,99+/-0,07). Dependence deltasigma on solution temperature is of an exponential character with the activation energy Esigma=0,30+/-0,01 ev. In the temperature range studied (248--298 degrees K) the ratio between the recombination velocity constant and the mobility of ion-radicals Chlalpha+ and Q-(Kp/mu) is shown to be equal (8+/-1)X 10(-8) cm-v. The activation energy for the dissociation of coulomb pair (Chlalpha+Q-) into free ion-radicals Epiapproximately0,1 ev is evaluated. The value of total mobility of negative and positive ion-radicals is calculated from the date obtained and literature ones: mu=(1,0+/-0,2)X10(-5) cm2/v-sec.


[Interaction of the nuclear proteins protamine and histone with charged bilayer membranes]. The interaction of nuclear proteins of protamine and histone with neutral and charged BLM was studied. Anion and cation detergents were used to create the surface charge. The surface density of charges in BLM was comparable with that in biomembranes. Protamine and histone increased the electroconductivity of negatively charged BLM for anions and cations correspondingly. It is suggested that the surface charge of the membrane may influence the ion transport directly and indirectly due to the interaction of the membrane structures with charged proteins present in the surrounding medium.


[Characteristics of Debye potentials in cell structures]. The activity of the cellular system is accompanied by the changes of substrate concentrations and excreted substances in the medium. This event brings about essential changes of the medium electrical properties. For the accomplishment of stationary metabolism the following condition should be fulfilled B=--2nsquare rootA, where n=1,2...., A and B are some functions depending on the diffusion coefficient of the substrate and excrement, their molecular weights, dissociation coefficients, membrane permeabilities and other parameters of the cellular structure.


[Fluorescence analysis study of the structural lability of biomembranes and their components. I. Bovine serum albumin]. The binding constants, quentum yield and temperature dependence of the fluorescence of ionic (1-anilinonaphtalin-8-sulphinate) and neutral (N-phenyl-1-naphtylamine) probes were studied on the molecules of bovine serum albumine with the change of pH and solution ionic strength. On the basis of the data obtained the nature of sorbing forces and structural properties of the albumine molecule concerned are discussed.


[Fluorescence analysis study of the structural lability of biomembranes and their components. II. Higher fatty acids]. Binding constants, quantum yield and temperature relationship of the fluorescence of ionic (1-anilinonaphtalene-8-sulphonate-ANS) and neutral (N-phenyl-1-naphtalamine-PNA) probes have been studied on micellae and ufasomes of natural fat acids. The following regularities have been obtained: 1. The Anion dye (ANS) sharply decreases the intensity of fluorescence on fat acid structures while alkilating the medium, it is not practically bound with them at pH-7; 2. The neutral dye (PNA) shiws no fluorescence on micellae of the limited fat acids and is comparatively well bound with urasomes. The binding constant quantum yield of PNA fluorescence significantly decreases during the transition from the ufasomes of oleic acid to those of polyunsaturated fat acids. 3. The temperature relationship of PNA fluorescence intensity sorbed on oleic acid ufasomes shows twists in the region of 16--20degreesC and 46--52degreesC. The first transition is connected with the melting of potassium oleate.


[Formation of purple membranes during salt bacteria cultivation]. Experiments have been carried out on cultivation of halophile with probe selection in the interval of 1--2 hours to record the spectra of repeated disturbed completed inner reflection. Periodicity in the changes of spectral characteristics of the culture with the interval of 20--24 hours is revealed. A clearly expressed dichroism of the amid II band of the membrane complex is found, the absence of this dichroism in the protein isolated from the membrane complex is stated. It is suggested that dichroism revealed is a specific feature of the presence of purpuric membranes in the cells. Spontaneous plane orientation of protein macromolecules in purpuric membranes is established. The level of dichroism of amid II band is shown to depend on fermentation conditions of salt bacteria.


[Photochemical and spectral properties of photosystem-2 subchloroplast fragments, highly purified from photosystem-1 mixtures]. A rather simple method of isolation of photosystem 2 fragments, which are highly purified from Photosystem 1 admixture, has been developed on the basis of combined action of detergents and differential centrifugation. The isolated fragments are characterized by insignificant content of P700 (one molecule per 10500 molecules of chlorophyll) and by high ratio of band values at 685 and 735 nm in the low temperature emission spectrum of fluorescence (F685/F735=5.9). The data on photochemical activity and ability for photoinduced changes in fluorescence prove that the activity of Photosystem 2 is retained both at the level of reaction centre operation and at that of water photooxidation with oxygen evolution.


[Spectrophotometry of individual Chlorella cells]. A research of optical properties of individual microalgae Chlorella vulgaris cells was performed under various conditions of cultivation. On the basis of cell absorption spectra measurements in the visible spectrum region chlorophyll "a" absorption maxima are estimated to fall within the intervals of 669-675 nm for the red region of the spectrum and 429--436 nm for the blue one. Concentration of chlorophylls in the cells of the diameter from 2,8 up to 3,3 micrometers was found to increase considerably for algae grown both in continuous denisty static and periodical regimes. Integral optical density of individual Chlorella cells in the range of 400-750 nm grows with cell diameter increase. This increase appears to be most intensive in the cells grown in density static regime. A correlation was also established between algae cell dimensions and the general maxima position (correlation coefficient has a positive sign and absolute value near unit). With cell diameter growth the absorption maxima shift to the region of long waves.


[Quantum productivity of different areas of the spectrum during cultivation of an asynchronous Chlorella culture]. The data are given of calculation of quantum productivity of chlorella asynchroneous culture during 7 hour development in different spectrum regions. High quantum productivity when chlorella develops in the green spectrum region is shown.


[Effect of light of different spectral composition on pigment accumulation, productivity and effectiveness of use of absorbed energy in photosynthesis during the developmental cycle of Chlorella]. The paper deals with the effect of light of different spectral composition on the duration of developmental cycle, pigment accumulation, productivity and efficiency of the use of absorbed energy in photosynthesis during the developmental cycle of Chlorella. An extremely high efficiency of using the green spectrum region in photosynthesis (21,0%) was observed. The efficiency of using absorbed radiation of the red (12%) and blue (6%) spectrum regions is also very high, but significantly lower than that of the green one. The activity of metabolic processes in Chlorella cells differs in various spectrum regions during different developmental cycles and is determined by the acting spectrum.


[Use of a mathematical model of erythropoiesis to study the recovery process in mice exposed to acute x-ray irradiation]. The model described in the preceding paper was used (after introducing several further presumptions of a radiobiological nature) for the interpretation of the dynamics of erythropoietic recovery, experimentally studied by the authors in mice after acute X-irradiation. The solution of equations in the model was carried out by a digital computer, finding some (not yet experimentally determined) quantitative characteristics of the system by trial and error. A satisfactory degree of agreement in the behaviour of the model with the experimentally determined course of recovery seems to indicate the validity of the basic assumptions of the model, esp. the existence of the negative feedback between erythroid populations of the bone marrow and spleen.


[Rate of excitation propagation in a reduced Hodgkins-Huxley model. II. Slow relaxation of the sodium current]. The influence of sodium current activation on the value of nerve excitation conduction velocity is investigated on the basis of Hodgkin-Huxley model. The potassium activation and sodium inactivation are considered as slow processes which do not develop to an appreciable extent in the region of conduction velocity formation. The system of equations was derived and solved analytically after neglecting the dependency of sodium relaxation time on potential; the approximation of steady-state sodium activation was also used with the help of Hevyside function. The algebraic equation for conduction velocity was obtained; its solution has a simple analytical form in two limits of rapid and slow sodium current relaxation. The comparison with the experimental data has shown that at not very high temperatures the slow (compared to the potential dynamics) sodium current relaxation approximation is more appropriate. The dependency of impulse velocity on capacitance and conductance of the fiber was analyzed.


[Evaluation of synaptic potential dynamics from evoked impulse activity of neurons]. To evaluate intracellular potentials in the region of spike initiation of function lambda (t) is suggested which describes the dependence on time of the density of conditional probability of generation by the neuron of the first impulse in response to the stimulus. Qualitative correspondence of the dynamics of membrane potentials and function lambda (t) is demonstrated on the analog model. The application of the function lambda (t) to the classification of the neurons of auditory system is shown to be promising. The difference between the function lambda (t) and normalized poststimulus histogram allows to evaluate the refracteriness of the neuron.


[Model of the impulse activity of a neuron receiving a stationary impulse imput]. The stationary model of spike activity of a single neuron is considered. This model exponential decay and constant threshold can be described as discontinuous one. The problem of calculation of Laplas' transform the probability density function (PDF) of interspike interval (ISI) can be reduced to the boundary problem for the usual differential equation. For the exponential PDF of the magnitude of the PSP the Laplas' transform of ISI PDF is expressed by special functions. The mean and standard deviation of ISI for different combinations of parameters were plotted with the aid of computer. The experiment without intracellular recoding, allowing to estimate the values of certain physiological parameters of a neuron on the basis of the model is proposed.


[Method of evaluating the synaptic input to a single mesencephalic neuron]. The mathematical model of the spike activity of a neuron with synaptic input from many other neurons [1], describes adequately the firing of 5 from 7 neurons in the tegmentum of mesencephalic cat and changes of their activity evoked by glutamate iontophoresis. For these 5 neurons the estimates of the PSPs' average frequency of the threshold depolarization and of the constant decay of the EPSP were received. For different neurons the values of these parameters are 4--100 KHz, 100--800 average unitary EPSPs and 4--30 msec correspondingly. The stationary value of the average membrane potential (SVAMP) in all 5 neurons was removed significantly from the resting potential toward the threshold potential. SWAMP could be changed by the glutamate iontophoresis in such a degree to overlap the threshold potential.


[Work of the human visual system. I. Adequate visual stimulus]. It is shown that the adequate stimulus permitting to detect the presence of colour differentiation in the visual field is the change of relative space-time differences of light actions in different retinal points. Differences only in space or only in time are not sufficient for perception.


[Correlation model of object recognition by echolocating animals]. The model proposed in an attempt to find out physical bases of object perception during echolocation. It is shown that echolocational perception can be provided with correlational treatment of corresponding signals. The character of objects is determined by the comparison by echo probing accepted in the given cycle with typical distortions remembered in the course of individual experience of the animal. The distortions take place during the reflection of the probing impulse from these or those objects. "Binding" of the objects according to distance may be carried out by using the choice of typical distortions for corresponding correction of the copy of probing impulse, serving as a bearing signal of distance correlometer. The response of correlometer to the echo from correctly perceived target increases. The block-scheme of such correlation perception during echolocation is given. Performance of some experiments allowing to check and refine the model considered.


[Kinematics of metachronous walking. III. Invariants]. The concept of a kinematic space for a locomotor system is introduced and regime of locomotion is defined as a continued one-dimensional manifold of this space. The problem of describing of locomotion is set (settled) by kinematic invariants. It is shown that metachrony of such millipedes as Scolopendra and Julus can be considered as a special case of some "relativity principle", on the basis of which the expression of metachrony invariant has come out. The attempt is made to use this principle for the determination of step's invariants of each individual leg too.


[Model representation of rat motor behavior during electric self stimulation of the brain. II. Concretization of function shape. Comparison with experiment]. In this chapter the function of activity of the motor behavior in selfstimulation situation and function of the stimulation of the brain are determined. Solutions of the equation give the relation between the motor behavior and parameters of stimulation. The solutions agree with many experimental data in selfstimulation situation in the Skinner's box.


[Photovoltaic effect in pigment films in contact with an electrolytes. V. Theory of the Becquerel photovoltaic effect in porous films of phthalocyanine]. In accordance with literature and our experimental data a theoretical analysis of the model system metal-porous film of the pigment-electrolyte was carried out at stationary illumination in the regimes of photocurrent and photopotential. The main properties and positions of the model are supported experimentally. Specific behaviour of the photovoltaic system considered resides in the discovered dependence of the transfer mechanism on the value of catode potential of the electrode.


[Frequency relations of capacitance and conductance of the system electrolyte--membrane--electrolyte in a model framework]. An electrodiffusion model of immediate permeability of ions through the lipid membrane was considered. The model suggests the existence of finite immovable layers of the electrolyte near the membrane. A technique is given for linearization and obtaining analytical solutions of the time-dependent electrodiffusion equations for one ion species. The expression for admittence of the system was obtained. The model allowed to obtain the curves of c (omega) and g (omega) which agreed with the empiric ones.


[Distribution of small hydrophobic molecules in membranes. I. Artificial lipid membranes]. A hydrophobic uncharged fluorescent probe of 4-dimethylaminochalcone (DMC) interacted with synthetic phospholipid membranes. Comparison of absorption spectra and fluorescence of DMC in the membranes and organic solvents shows that in the membranes the DMC molecules are located not in the hydrocarbon layer but in the polar regions near the surface. The probe is distributed regularly along the surface forming no dimers and clusters. Polar groups which surround the probe in the membrane are less mobile than the molecules of organic solvents at the same temperature. The evaluation shows that the relaxation time of polar groups in the probe environment is longer than 0.15-10(-9) sec. The DMC molecules may be located in different sites of the membrane surface, which seem to differ from one another in the mobility of polar groups.


[Comparison of discrete models of charge transfer in thin membranes. I. Stationary regime]. The model of the ion transport through thin membranes is discussed. It is assumed that there exist some steps of the ion transfer in the membrane volume. Theory of absolute rate of processes is used to derive an equation for stationary transmembrane flow. As a result the thory parameters are connected with the form of potential energy curve of permeable ions into the membrane phase.


[Properties of bilayer lipid membranes with different surface charges in the presence of tetraalkylammonium salts]. It is shown that with the growth of the radius of tetraalkylammonium ions the conductivity of the membrane increases. With an increase of the dimensions of penetrating ions the maximum cation selectivity reached in the beginning decreases with a further growth of cation radius. A negative charge on the membrane surface results in a higher cation selectivity and conductance mechanism is observed at the transition to the cations with a large radius at their high enough concentration in the aqueous solution. It can be explaind by the formation of triplet in the membrane phase which aid in the penetration of C1-.


[Use of the fluorescent probe method to study the interaction of barbiturates with biological membranes]. The binding of the negatively charged fluorescence dye ANS and neutral dye NPN2 with lipid and erythrocyte membranes in the presence of barbiturates was studied. It was found that barbiturates decreased the amount of binding sites of ANS and NPN2 with membranes did not affect the quantum yield and the dissociation of the membrane-dye complex. It was shown that all barbiturates investigated were bound with the membranes in a neutral form.


[Permeability of plane bilayer lipid membranes in the presence of sarcoplasmic reticulum vesicles]. Interaction between vesicles of sarcoplasmic reticulum (VSR) and bilayer lipid membranes (BLM) was investigated. VSR were added into the membrane-surrounding solution. For the formation of complex VSR-BLM the surface of BLM was charged positively by adding 10(-6) M acetyltrimethylammonium bromide and the transmembrane electrical potential was applied in the negative direction (the positive direction was chosen from inner section of camera with VSR to outer section). The formation of complex VSR-BLM proceeds via two stages. The second stage is accompanied by the formation of nonselective channels of conductivity, perhaps, aqueous pores.


[High resolution NMR study of mitochondria and submitochondrial fragments]. The PMR spectra of mitochondrias, inner and outer mitochondrial membranes and also, matrix and intermembrane material are presented. The essential effect of sonication on the structure of inner membranes of mitochondrias is demonstrated.


[Study using the Noble model of excitation propagation through a branching node]. Excitation propagation through a branching node with 3 thin branches fused into a thick one has been studied on Noble model. When the ratio of the diameters of thin and thick branches equals 1 : 10 the propagation is blocked. When the diameter ratio is 1 : 8 and excitation comes asynchroneously (along one of input branches 10 msec later than along two others) a 30 msec delay of propagation is observed. The importance of the results obtained for explaining atrio-ventricular delay is discussed.


[Principles of neuronal organization. I. Memory as a process of information transmission]. The process of memory is considered as the process of information transmission from "wrighter" to "reader" with an aid of memory device. A special attention is paid to memory which work with errors: "false memorising" and missing some words. The results obtained are useful for evaluation of possibilities of neuronal memory circuits of Brindley-Marr type.


[Mathematical model of autoimmunity].

[Mathematical model of autoimmunity]. A mathematical model of autoimmunity is developed. This model is a system of two nonlinear differential equations, which describe the concentration dynamics of tissue cells and agressive lymphocytes. An analysis of the solutions shows that this model reproduces general behaviour of autoimmune diseases.


[Rate of excitation propagation in a reduced Hodgkins-Huxley model. III. Integrodifferential equations]. The Hodgkin - Huxley system of equations is reduced to single integral-differential equation in neglection of slow variables dynamics. Two limiting cases of fast and slow sodium activation processes are considered. The first case leads to a nonlinear differential equation for the potential, the second one - to an ordinary differential equation with a known source as a function of coordinate. Such a simplification is due to approximation of steady-state sodium activation variable with the help of Heviside function. The validity of this approximation is discussed; the corresponding error is estimated by calculation of the second approximation for the source function.


[Model of a passive 3-dimensional anisotropic syncytium as a continuous medium]. A model is being proposed for analysis passive electrical properties of the syncitium with anisotropy. In terms of the model the potential is expected to decay as approximately e-r/r with an increase of the distance, r, from a polarising electrode. Input resistance of the three-dimensional syncitium loosely depends upon the resistance of electrogenic membrane, and thus should be mainly accounted for by the resistances of the myoplasm and intercellular contacts.


[Work of the human visual system. II. Color]. In the first part of this work [1] the author presented the expression for so called adequate visual stimulus. This expression describing the change of relative space - time differences of light actions in different retinal points defines the conditions necessary for producing visual sensations. In this paper author makes a statement that the quality of visual sensation (the percieved colour) can be evaluated by integrating the expression for the adequate visual stimulus both in time and in space. The integration in space is fulfilled starting from the extreme periphery of the retina, which is usually illuminated by scattered light averaged over the whole visual field. Human visual system works in such a way that the light action in the extreme periphery plays a role of the unit for scaling of visual sensations.


[Spectral characteristics of stimuli and responses in a complex receptive field]. Responses of a complex receptive field of visual cortex of the cat are determined by the energy of stimuli in the band pass of equivalent space frequency characteristic of the receptive field. This is a proof that the complex receptive fields are spatial frequency band pass filters.


[Transformation of angular accelerations by the semicircular canal system of the vestibular apparatus]. Transformation of angular accelerations by the system of three semicircular channels is considered which takes into account mutual influence of vertical channels through a common crus.


[Computer modeling of human movements].

[Computer modeling of human movements]. A dynamic model for studying man's movements is proposed. Lagrange equations of the second order are used. Differential equations of the model are presented in the matrix form, and all the coefficients involved are calculated from recurrent formulae. The dynamic model described is easily algorythmized. Differentiating operations can be thus avoided which are realized on electron computers with difficulities.


[Modeling human spatial movement].

[Modeling human spatial movement]. The problem of determining biodynamical characters of human locomotion in space is considered. The method for calculating the forces and the moments in joints for 15-link model of support-motive apparatus of man is discussed.


[Temperature dependence of the electronic absorption spectra of polynucleotides and their components]. The temperature dependence of UV-absorption spectra of solutions nucleic bases, nucleosides, nucleotides and metilated bases, uncapable of tautomerization has been studied. The nature of such dependence, its connection with hypochromic effect is discussed. It is shown that for some methods of investigating polynucleotides it is necessary to take into account the temperature changes spectra of monomers.


[Internal rotation potentials in polynucleotides]. An empirical potential function for internal rotation around P-O bonds in polynucleotides is suggested. Its parameters have been determined taking into account the result of quantum mechanical calculations for dimethylphosphate.


[Dynamic model of protein behavior in water]. In the basis of the suggested model lies the hypothesis that during the evolution process biological macromolecules "learnt" to use the ability of water through cooperative transition from the rigid phase to the liquid one without a change in free energy for the regulation of their conformation. In accordance with the results of a number of investigations it is assumed that the protein molecule exists in thermodynamic equilibrium between two conformers with different accessibilities of nonpolar cavities to water and with different effective volumes. Deformation of both or one of the conformers under the effect of specific or nonspecific influences removes the system (protein+water) from the equilibrium, and as a result of the relaxation process the system achieves a new equilibrium state. A change in the equilibrium constant between the conformers determines the change of the average protein volume. The entropy and entalpy of protein and water in the system (protein+water) change during this process in a counterphase manner. Phase transition of water, involved between the subunits of oligomeric protein, may play a significant role in the mechanisms of allosteric effects.


[Interaction of human serum albumin with luminol]. Chemoluminescent and fluorescent studies of the interaction between serum albumine and luminole have been carried out. An increase of chemoluminescent intensity and quenching of luminole fluorescence dependent on protein concentration has been observed. Possibility of complex formation and the mechanism of fluorescence quenching with luminole are discussed.


[Effect of aniline and hydrazine derivatives on reversible oxygen addition in model systems of cobalt complexes of etioporphyrin and alpha, beta, gamma, delta-tetraphenylporphine]. The influence of aniline and hydrazine derivatives on the reversible oxygenation of cobaltous complexes of etioporphyrin I and alpha,beta,gamma,delta-tetraphenylporphin has been studied by means of ESR and electronic spectra. The formation of stable six-coordinated complexes with the said reagents prevents the oxygenation. The excess of hydrazines cause the destruction of porphyrin nucleus. The formation of intermediate dihydroporphyrins (chlorins) has been noticed.


Effects of calcium ions on pyruvate kinase from human erythrocytes. Ca2+ ions have a biphasic effect on the allosteric pyruvate kinase (EC 2.7.1.40) from human erythrocytes: Ca2+ is an activator at low phosphoenolpyruvate (PEP) concentrations: at increased PEP concentrations Ca2+ behaves as an inhibitor. In the presence of ATP the same effect was observed and at low PEP concentrations Ca2+ ions can completely abolish the ATP inhibitory effect. At high Ca2+ concentrations there is a loss of the cooperativity towards PEP. The enzyme activated by fructose-1,6-diphosphate (FDP) is inhibited by Ca2+ ions at all concentrations of PEP tested. Mg2+ ions are not able to counteract the activation by Ca2+ ions at low PEP concentrations. The results are interpreted on the basis of the model of Monod.


[Isolation and physico-chemical properties of oligosaccharides of human milk]. From a non-dialysable fraction of human milk the authors have isolated 30 oligosaccharides by combining anion exchange and paper chromatography. These oligosaccharides (MW 998 to 3113) contain D (+)-galactose, L (-)-fucose, N-acetyl-D (+)-glucosamine, N-acetyl-D (-)-neuraminic acid in variable proportions and one single D (+)-glucose residue in terminal reducing position. The characteristics of the oligosaccharides are those of the so-called "Polonovski and Lespagnol gynolactose". These sugars do not originate from glycoproteins nor glycolipids. The authors suggest that the biosynthesis of human milk oligosaccharides is due to an activation of glycosyltransferases related to blood group substances, induced by lactose. They base this hypothesis on the fact that, as demonstrated by Strecker and Montreuil, spontaneous or glucose, galactose and lactose induced meliturias are accompagnied by an important urinary excretion of blood group substance related oligosaccharides.


[Photopotential during the photochemical reaction of chlorophyll with duroquinone]. Under the illumination of ethanol solutions of chlorophyll "alpha" and "beta" in the presence of duroquinone positive photopotential (PP) appears, the sign of which is not changed with an increase of pH. However, if duroquinone is used, which had been illuminated with white light in the absence of air, in ethanol, which results in an increase of concentration of its reduced forms, at neutral weakly alkaline pH the PP sign gets negative. This fact supports the assumption that the change of PP sign at the change of pH when parabenzoquinone is used as an oxidizer results from the change of the direction of electron transfer during photoreaction. During photoreaction of pheophytin incapable of photooxidation with duroquinone and disposed to photoreduction, PP at all pH is negative.


Location of the cistron of the tobacco mosaic virus coat protein. Treatment of tobacco mosaic virus (TMV) RNA with T1 RNase under mild conditions cuts the RNA molecule into a large number of fragments, only a few of which may be specifically recognized by disks of TMV protein. It has been shown elsewhere that these specifically recognized RNA fragments are a part of the coat protein cistron, the portion coding for amino acids 95 to 129 of the coat protein. It is reported that different size classes of partially uncoated virus particles were prepared by limited reconstitution between TMV RNA and protein or by partial stripping of intact virus with DMSO. Both procedures produce nucleoprotein rods in which the 5'-terminal portion of the RNA is encapsidated and the 3'-terminal region is free. The free and the encapsidated portions of the RNA were each tested for the ability to give rise to the aforesaid specifically recognized fragments of the coat protein cistron upon partial T1 RNase digestion. It was found that only the 3'-terminal third of the virus particle need to be uncoated in order to expose the portion of the RNA molecule from which these fragments are derived. We conclude, therefore, that the coat protein cistron is situated upon the 3'-terminal third of the RNA chain, i.e. within 2000 nucleotides of the 3'-end.


[Effect of the dielectric constant of the medium on the photooxidation of chlorophyll a by parabenzoquinone]. Spectrophotometric study was carried out of the effect of medium polarity on the parabenzoquinone photooxidation of chlorophyll "a" at lower temperature using as solvents toluene and CCl4 containing different quantities of polaric solvents, methanole, ethanole, amilic alkohol, acetone. It is shown that the photoreaction with the formation of primary photooxidized form of the pigment starts only if some amount of the polar component is in the medium. The data are in favour of the suggestion that chlorophyll and quinone in non-polar medium form an reaction complex which disintegrates under the given conditions at a definite value of medium polarity.


Characterization and purification of messenger RNAs containing poly A in insect imaginal disks. The presence of a fragment of polyA resistant to both T1 and p ribonucleases in mRNAs extracted from wing imaginal disks of an insect, Pieris brassicae, is reported. Its length was approximatively 150 nucleotides. PolyU sepharose affinity chromatography was subsequently used for purification of these polyA(+)mRNA molecules. Analyses on sucrose gradients showed a good recovery of poly(+)molecules characterized by their size (20-100 S) and a polydisperse pattern. These mRNAlike species represent 2-3 per cent of the total radioactivity incorporated into RNA in 3 hours of labeling. Sequential extractions were carried out to provide cytoplasmic RNA rich fractions (4 degrees C) and nuclear rich fractions (45 degrees C). When assayed for the presence of polyA(+)RNA, molecules extracted by these two sequential methods were found to be very similar in their polyA content.


[Participation of oxygen in the reduction of methylviologen, photosensitized by chlorophyll, in an aqueous solution of detergent]. Dependence of chlorophyll "a" photosensitized reduction of methylviologene with tiourea on the temperature of reaction mixture was studied in aerobic conditions in triton X-100 aqueous solution. It was found that the reaction consisted of two stages: the light and dark ones. Photosensitized oxidation of tiourea with air oxygen proceeds at the temperatures up to -70 degrees C. Reduction of methylviologen is a dark stage for which diffusion processes are necessary. The role of hydrogen peroxide in the reaction studied has been investigated. It has been shown that hydrogen peroxide is not the "initiator" of the reaction which results in the reduction of methylviologen. Reduced glutation and the mixture of reduced and oxidized glutations were used as electron donors in photosensitized reaction in the presence of air oxygen. An increase of the depth and rate of the reduction of methylviologen under aerobic conditions as compared to anaerobic ones points to the formation of more active reducers than the initial electron donor.


Cell surface changes during myoblast differentiation: preparation and carbohydrate composition of plasma membranes. A technique for the preparation of plasma membrane from a skeletal muscle myogenic cell culture is described. Electron microscopic and enzymatic studies indicate that the preparation has kept its morphological integrity and has negligeable amount of cellular contiaminants. Carbohydrate composition studies have shown that the differentiated cells contain less hexosamine and sialic acid but accumulate glucose and galactose; the latter increase reflects the presence of a glucose-galactose-hydroxylysine unit which appears at the cell surface when myoblasts reach confluency.


[Incorporation of tritiated thymidine into DNA of rat liver: a critique of various evaluation methods]. We have measured the incorporation of 3H-(methyl)-thymidine by cell cultures of rat foetal liver and in vivo by the livers of young rats stimulated by casein, in order to compare three methods for the extraction of DNA. The DNA was extracted by three different techniques: perchloric acid precipitation, trichloroacetic acid precipitation and phenol extraction, and its specific activity was determined. The radioactive labelling was also determined for the lipid, ribonucleic acid and protein fractions for the two first methods, in both of which 70 p. cent of the incorporated tritium is found in the DNA fraction and about 10 p. cent in each of the other fractions. The determination of the specific radioactivity of DNA gives similar results for the three extraction methods. However, since larger yields were obtained by both acid precipitation techniques than by phenol extraction, we believe them to be more suitable for studies on cell cultures.


[Effects of thyroidectomy of the rat on the structure and functions of skeletal muscle mitochondria]. Mitochondria used in the present study were isolated from skeletal muscle of normal and thyroidectomized rats. The preparations were controlled by electron microscopy. It was not possible to find any morphological change induced by thyroidectomy, nevertheless, some difference appeared in the cytochrome contents which were slightly decreased. Oxygen consumption rates of thyroidectomized rat mitochondria were decreased when the particles were maintained in states 3 and 4 in the presence of various substrates, but the P/O ratios were not modified. The activities of mitochondrial enzymes were in general slightly affected by thyroidectomy except for glycerol-1-phosphate cytochrome c reductase and NADH rotenone sensitive cytochrome c reductase which were decreased and for glutamate dehydrogenase activity which was increased. The tRNA nucleotidyltransferase activity found in the mitochondrial matrix was not influenced by the absence of thyroid secretion. Normal rat muscle mitochondria incorporate 14C-leucine with an artificial ATP-generating system or with a respiratory substrate. The amino acid incorporation was decreased by thyroidectomy. Muscle mitochondria analyzed by polyacrylamide gel electrophoresis contained more than 30 protein components with MW ranging from 10.000 to 135.000. Thyroidectomy lowered the amount of a fraction of about 54.000 MW. It is not impossible that all the data observed in the absence of thyroid secretion are in relation with changes induced in the mitochondrial genome as previously shown in mitochondria isolated from liver or thyroidectomized rats.


Effect of phosphate and ionophores on (14C)-NEM incorporation in mitochondrial membranes and relationships with phosphate carrier system. Phosphate transport in mitochondria was investigated with respect to its inhibition by NEM. The reactivity of the Pi carrier SH groups was influenced by phosphate or ionophores during preincubation before the addition of NEM. Furthermore in order to obtain some mitochondrial protein fractions where the typical effects of phosphate and ionophores on [14C]-NEM fixations were observed, mitochondria were submitted to hypotonic treatment and sonication. The following results were obtained: 1. -- Phosphate and grisorixin (a new ionophore of the nigericin group) decreased the inhibition of phosphate transport by NEM. The same effect was observed for [14C]-NEM incorporation. 2. -- Valinomycin increased [14C]-NEM incorporation. The valinomycin effect was abolished by phosphate. ClCCP alone affected [14C]-NEM incorporation slightly. Valinomycin plus ClCCP decreased NEM inhibition of phosphate transport and [14C]-NEM incorporation like grisorixin. 3. -- The variability of SH group reactivity can be interpreted by a control of SH group accessibility by transmembrane delta pH as previously suggested. 4. -- Typical effects of phosphate or ionophores were observed in whole pig heart and rat liver mitochondria. These effects were enhanced in the same supernatant protein fraction resulting from sonication in pig heart mitochondria : phosphate decreased [14C]-NEM incorporation by 1,50 nmoles/mg protein, grisorixin by 0.95 nmoles, whereas valinomycin increased it by 0.75 nmoles. For rat liver mitochondria the phosphate effect and the valinomycin increased it by 0.75 nmoles. For rat liver mitochondria the phosphate effect valinomycin effect on [14C]-NEM incorporation were observed in the subparticular fraction obtained after sonification.


[Modification in all-trans-retinal, 9-cis-retinal and 11-cis-retinal caused by exposure to sunlight]. Results indicate that diffused sunlight determines in the molecules of all-trans-retinal, 9-cis-retinal and 11-cis-retinal a process of photoinduction with the formation of an unknown photoproduct.


[Primary structure of cytoplasmic aspartate aminotransferase from pig heart muscle. Amino acid sequence of peptides from cyanogen bromide hydrolysate]. Amino acid sequences were determined for the six peptides from cyanogen bromide hydrolysis of cytoplasmic aspartate aminotransferase. These peptides accounted for 177 amino acid residues of the enzyme. Partial sequence of N-terminal peptide accounting for 212 amino acid residues of enzyme was also determined.


[Analysis of ribosomal proteins and ribosomal subunits of pea seeds by electrophoresis in polyacrylamide gel]. The amino acid composition of overall protein of ribosomes and ribosomal subunits of pea seeds has been found typical of ribosomal protein. Electrophoresis in polyacrylamide gel demonstrates that proteins extracted by the solution of 3 M LiCl-4 M urea from purified ribosomes of pea seeds move towards the cathode at pH 2.2 and separate into 41 components. Electrophoresis in a tris-glycine buffer at pH 9.2 does not reveal any substance corresponding to acid proteins. Similar distribution patterns are observed when ribosomal particles are isolated with or without triton (0,5%). The treatment of ribosomes by deoxycholate results in some changes, depending on the detergent concentration. All the protein components detected in ribosomes, except one, are present in the subunits. Proteins of large and small ribosome subunits produced 26 and 21 components respectively in polyacrylamide gel electrophoresis. The distribution patterns of proteins of the two subunits appear to be different. The majority of the components of the large and small subunits differ in mobility. The data obtained suggest considerable specificity of the protein composition of 60S and 40S subunits of 80S ribosomes in higher plants.


[Biosynthesis of proteins and ribonucleic acids in red and white rat skeletal muscles]. Protein biosynthesis is studied in red and white rat shank muscles in vitro. It is found that the incorporation rate of 14C-lysine in red muscle was 2-fold higher than that in white muscle. The difference in the lysine incorporation rate into muscle proteins studied increased with the increase of lysine molar concentration in the incubation medium, which was probably due to a selective protein synthesis activation in the red muscle. A higher level of 14C-lysine incorporation in red muscle proteins was found under similar uptake of the labelled amino acid in both red and white muscles. RNA synthesis rate was the same in both muscles and its inhibition with actinomycin D did not affect the ratio of protein synthesis rates in red and white muscles.