Biological changes of human cutaneous nerves caused by ultraviolet irradiation: an ultrastructural study. Three white male volunteers were irradiated by long wave ultraviolet (UV-A) and by solar simulating radiation (SSR). An acute change of cutaneous nerves was found following a single exposure of UV-A irradiation. Non-myelinated Schwann cells and perineural cells in the papillary and reticular dermis were degenerated. Axoplasms appeared to be electron-dense, but were less affected than Schwann cells. After long-term repeated exposure, many free nerve endings were found in the dermo-epidermal junction above the basal lamina and some of them made a terminal enlargement. In one instance an axon made a swelling. Dermal free nerve endings also seemed to be increased in number and some of them were situated immediately beneath the melanocytes which were active in melanogenesis. Multiplication of basal lamina of the Schwann cells and perineural cells was observed. Amorphous material was precipitated around the non-myelinated Schwann cells. After a single exposure of SSR irradiation the degeneration of Schwann cells and axons in the dermo-epidermal junction was less severe than after UV-A and changes were minor in the reticular dermis. After repeated exposure, intra-epidermal proliferation of free nerve endings was detected. Dermal nerves were slightly affected. No intra-epidermal free nerve endings were observed in controls. The intra-epidermal proliferation of free nerve endings was confirmed following repeated UV exposures. Melanocyte-nerve association is suggested to be the cause of stimulating melanocyte activity.


Oral photochemotherapy in the treatment of lichen planus (LP). Clinical results, histological and ultrastructural observations. Seven patients with diffuse lichen planus were treated with oral photochemotherapy. Remission was effected in 6 cases. The only failure may be attributable to a low UVA dose. Histological examination after treatment showed disappearance of the superficial dermal lymphocytic infiltrate. Ultrastructural study revealed nuclear alterations of keratinocytes and nuclear and cytoplasmic changes in superficial dermal cells. Various theories concerning the mode of action of photochemotherapy in lichen planus are discussed in the light of these observations.


Suppression of epidermal proliferation by ultraviolet light, coal tar and anthralin. 360 nm ultraviolet light (UVA) plus coal tar depresses mitosis and DNA synthesis in epidermal cells. UVA has no effect by itself. In some models coal tar alone can partially depress DNA synthesis. 254 nm ultraviolet light (UVC) and 290--320 nm ultraviolet light (UVB) do not enhance depression of DNA synthesis by coal tar. Dithranol will suppress mitosis and DNA synthesis of epidermal cells but there appears to be no photo-activation by UVA. Dithranol suppression and suppression of DNA synthesis by UVB or UVC are additive when used together.


The relationship between serum viscosity, hypervolaemia and clinical manifestations associated with circulating paraprotein. In 44 of 56 patients with malignant paraproteinaemia the relationship of serum viscosity, plasma volume (PV), estimated blood volume (BV) and clinical findings was investigated and in the remaining 12 patients one or more of these parameters was studied. There was a correlation between increased PV and serum viscosity (r = 0.66, P less than 0.001). The retinopathy characteristic of the hyperviscosity syndrome (HVS) was always associated with serum viscosity greater than or equal to 3.8 and with hypervolaemia. The evidence that the retinal changes were related more closely to serum hyperviscosity than to hypervolaemia is twofold. First, there was a considerable overlap in the degree of BV expansion, but not serum hyperviscosity, in patients with and without retinopathy. Second, the retinopathy in a patient with Waldenström's macroglobulinaemia (WM) improved after plasma exchange with little change in BV. While bleeding was often associated with retinopathy seven patients with multiple myeloma (MM) had no retinopathy, viscosities greater than or equal to 4.3 and BV in the same range as patients with no clinical signs. Haemorrhage in such patients may thus be unrelated to the property of the paraprotein responsible for hyperviscosity. Measurements of PV in a patient with WM having repeated plasma exchanges for bleeding suggested that hypervolaemia may contribute to haemorrhage in some patients. It is suggested that the term 'HVS' should be restricted to patients with retinopathy and that hypervolaemia should be considered a characteristic feature of this syndrome.


Plateletpheresis by discontinuous centrifugation: effect of collecting methods on the in vitro function of platelets. The in vitro function of platelets collected by two different methods during centrifugal plateletpheresis was compared. The RBC method involves collecting platelets with red cells followed by a supplementary spin to remove them, whereas the no-RBC method requires collecting platelets only from the buffy coat without red cells. Platelet response to adenosine diphosphate (ADP), epinephrine and collagen was slightly reduced in platelet-rich plasma (PRP) prepared by no-RBC technique and was markedly decreased in samples obtained by the RBC technique when compared to prepheresis controls. The decrease in platelet response to ADP, epinephrine and collagen was apparent in three testing systems: aggregation, release of serotonin and reptilase clot retraction. Both plasma and platelets appeared to be affected by the pheresis procedure. Platelet preparations obtained by both RBC and no-RBC techniques showed an increase of platelet factor 3 activity and an enhancement of aggregation, release of serotonin and clot retraction induced by thrombin as compared to prepheresis controls. Postpheresis platelet-poor plasma contains platelet membrane fragments which exhibit a high platelet factor 3 activity. The results showed that the RBC method, although providing a higher platelet yield, caused more qualitative alterations in platelets than in those obtained by no-RBC method, and that both methods of collecting platelets activated the procoagulant activity of platelets.


Abnormal platelet aggregation in severe combined immunodeficiency disease with adenosine deaminase deficiency. The platelets from a boy with adenosine deaminase deficiency-severe combined immunodeficiency disease (ADA-SCID) showed markedly subnormal aggregation in response to collagen and ADP. In contrast with normal platelets, ATP, AMP and adenosine had little effect in inhibiting ADP-induced aggregation of ADA-SCID platelets. These observations suggest that altered adenosine metabolism exists in ADA-SCID platelets.


The ultrastructural localization of factor VIII-antigen in human platelets, megakaryocytes and endothelial cells utilizing a ferritin-labelled antibody. By means of electron microscopy combined with the use of monospecific anti-factor VIII-antigen (VIIIR:AG) antibodies conjugated to ferritin, the subcellular localization of VIIR:AG in platelets, megakaryocytes and in endothelial cells has been established. The reported results suggest the possibility that the megakaryocyte is able to synthesize VIIIR:AG and also to secrete it by means of a microcanalicular system similar to that present in the endothelial cell. Platelets may derive their VIIIR:AG content partly from the megakaryocyte and partly from the plasma.


Immunologic studies of factor IX (Christmas factor). II. Immunoradiometric assay of factor IX antigen. A solid-phase two-site immunoradiometric assay has been developed which measures factor IX antigen levels as low as 0.0004 u per ml of plasma. In normal individuals, the factor IX antigen level correlated with the factor IX procoagulant level. In haemophilia B, 14 patients had markedly reduced antigen levels (less than 0.06 u/ml) and five had normal levels (greater than 0.60 u/ml).


Factor VIII coagulant activity in an African population in relation to a recognized standard. The normal range of factor VIII coagulant activity (derived from log potency ratio) in some sections of the Nigerian population has been established at 0.65--5.55 iu/ml with a geometric mean of 1.90 iu/ml. This was determined against an acceptable standard (MRC Human 68/413 with activity o.66 iu/ml). The distribution of the potency ratio was log normal. The level was not affected by age or an abnormal haemoglobin (Hb A + S or A + C). The mean activity in females was significantly higher than the mean value in male subjects. With the use of a stable standard, our results show that the conclusions of some previous studies in respect of some of the parameters such as population distribution but which did not use a recognized standard, were valid. Within the age limits of our subjects, age did not affect the population level of factor VIII coagulant activity.


Haemoglobin Vanderbilt (alpha2beta289Ser leads to Arg): a new haemoglobin with high oxygen affinity and compensatory erythrocytosis. Haemolysates of family members from three generations, all of whom had polycythaemia, were analysed by polyacrylamide gel electrophoresis at pH 8.8. Two closely spaced major bands were observed, one of which corresponded to Hb A and the other to a new mutant designated Hb Vanderbilt. Whole blood from a heterozygote for Hb Vanderbilt was analysed for oxygen affinity which was found to be much higher than that of normal subjects. Haemoglobin Vanderbilt was separated from Hb A using anion exchange chromatography. Cation exchange chromatography yielded a variant beta chain from which a mutant peptide was identified with a structure corresponding to residues beta83--89 with a Ser leads to Arg replacement at position 89. The oxygen affinity of 'stripped' haemolysates from the heterozygote was found to be much less sensitive to added organic phosphates than haemolysates from normal subjects. In while blood, the decreased sensitivity to 2,3-diphosphoglycerate results in an increased oxygen affinity, thus explaining the clinical observations of tissue hypoxia and compensatory polycythaemia.


The development of haemoglobin A2 in normal negro infants and in sickle cell disease. The development of haemoglobin A2 levels from birth to 3 years has been compared in normal, beta-thalassaemia trait, sickle cell (SS) disease, and S-beta-thalassaemia genotypes. Hb A2 levels were almost identical in normals and in children with SS disease at 1, 2 and 3 years. The most rapid increases in Hb A2 levels occurred before 6 months but levels were still rising at the end of the third year. Sickle cell-beta+ thalassaemia could be differentiated from SS disease by the higher Hb A2 levels between 6 months and 1 year. Insufficient data were available on S-beta o thalassaemia but since Hb A2 levels in this condition are generally higher than those in S-beta+ thalassaemia, differentiation from SS disease may may also be possible from the age of 6 months.


Paroxysmal nocturnal haemoglobinuria in Thailand with special reference to as association with aplastic anaemia. Eighty-five cases of PNH in Thailand were analysed, with emphasis on the comparison with European series and on an association with aplastic anaemia. Compared with European series, two points emerge: (1) the disease in Thai affects individuals of younger age group with a tendency to male preponderance; (2) the incidence of arterial and venous thrombosis is relatively rare. In association with aplastic anaemia, two main categories of PNH patients, are described, which differ in their clinical and laboratory citeria.


Leucocyte alkaline phosphatase activity during high risk pregnancies. 142 determinations of leucocyte alkaline phosphatase (LAP) activity have been done in 103 cases of high risk pregnancy. A statistically significant elevation of LAP score has been found in high risk pregnancies due to diabetes mellitus, toxaemia, renal diseases and third trimester haemorrhage, but not in pregnancies complicated by cardiac disease, chronic hypertension, Rh sensitization or anaemia.


Birth weight standards in a community of mixed racial origin. A prospective study of approximately 2000 consecutive deliveries at a north London hospital, with a mixed population distribution of Caucasian, British and Irish, Indian and West Indian mothers was made between May 1975 and August 1976. Most of the results are based on 1322 births of known gestational age. Babies of Indian mothers were found to be approximately 300 g lighter than their Caucasian equivalents at term, and by United Kingdom birth weight standards, 15 per cent of the babies of Indian mothers were below the fifth centile. Birth weights of babies of West Indian mothers ranged between those of the Indian and the Caucasians.


A comparison of biparietal diameter measurements using a real-time scanner and a conventional scanner equipped with a coded cephalometry system. In 131 patients a comparison was made between measurements obtained using a real-time scanner and those obtained using a conventional "B" scanner with an attached "coded cephalometry system": 69 per cent of the readings agreed within +/- 2 mm and, when the "B" scan reading was considered "good", 90 percent fell within this range. Between 14 and 28 weeks, gestational age diagnoses using the two methods were within one week of each other in 88 of 89 patients.


Use of portable real-time ultrasound scanner in district antenatal clinics. A portable real-time ultrasound scanner was transported to nine district antenatal clinics up to 35 miles from the base hospital. A total of 100 patients was scanned. During a scanning time of five to ten minutes, measurements of biparietal diameters were obtained easily, and in most cases details of placental location, fetal movement and the fetal spine were obtained.


Effect of smoking during pregnancy upon the haematological values of cord blood. Haematological indices in cord blood, measured by a Coulter Counter, in 50 mothers who smoked 10 or more cigarettes a day were compared with those in 75 control mothers who were non-smokers, but of similar age and parity. Smoking during pregnancy was associated with higher levels, of haemoglobin, and the haematocrit, as well as with higher red cell counts and a higher mean corpuscular haemoglobin. The percentage of fetal haemoglobin in cord blood was not affected by smoking. There was no correlation between social class and cord blood haemoglobin; but within social class groups, higher cord blood haemoglobin levels were associated with smoking. It is suggested that smoking during pregnancy stimulates fetal erythropoeisis.


Viscosity, haematocrit, fibrinogen and plasma proteins in maternal and cord blood. The viscosity at low shear rate of whole blood, plasma and serum, the haematocrit, plasma fibrinogen, plasma proteins, and IgM were measured in maternal and cord blood immediately following delivery. The whole blood viscosity in maternal blood (mean 19.96 +/- 3.74 centipoise or c/p) was similar to cord blood viscosity (mean 19.44 +/- 4.28 c/p). The mean haematocrit in maternal blood (0.385 +/- 0.026) was significantly lower than the cord haematocrit (0.488 +/- 0.39). Mean plasma viscosity (1.86 +/- 0.47 c/p) and plasma fibrinogen (4.25 +/- 0.75 g/litre) in maternal blood were significantly higher than cord plasma viscosity (1.12 +/- 0.19 c/p) and cord plasma fibrinogen (1.81 +/- 0.61 g/l). Mean serum viscosity (1.22 +/- 0.28 c/p) and mean IgM levels (2.38 +/- 0.36 g/l) in maternal blood were significantly higher than cord serum viscosity (0.90 +/- 0.15 c/p) and cord IgM (0.48 +/- 0.06 g/l). The low low levels of IgM and fibrinogen may protect the fetus from the increased viscosity that could be expected in association with a high haematocrit.


Triplet pregnancy.

Triplet pregnancy. A series of 14 triplet pregnancies has been analyzed. The older triplet mother had a better chance of fetal survival than the younger mother. Parity did not appear to have much effect on fetal survival but the maturity of the infants at birth had more influence than did birth weight, on their survival. The interval between the delivery of the second and third infants did not correlate with the poor prognosis for the last infant. Spontaneous breech delivery appeared to have a worse prognosis than assisted breech delivery. There was a high incidence of girls and they appeared to do better than the boys. There was a high incidence of monozygotic twin pairs in these triplet pregnancies.


Pulmonary ventilation in pregnancy.

Pulmonary ventilation in pregnancy. Serial tests of ventilatory function were made in 38 normal primigravidae during and after pregnancy. During pregnancy all patients showed major changes in tidal volume, functional residual capacity and residual volume. Minor changes were found in many other measurements, all of which occurred at an early stage of pregnancy. Most of the obvious alterations cannot be accounted for adequately by mechanical disturbance from the gravid uterus.


Myometrial response to a long-acting vasopressin analogue in early pregnancy. Intrauterine pressure was recorded for 4 to 6 hours in 21 healthy women having a therapeutic abortion at 6 to 9 weeks gestation. Fourteen of the women received an intravenous injection of 300 microgram of N-alpha-triglycyl-(8-lysine)-vasopressin (TGLVP) and seven were used as controls. Uterine tone and the amplitude and duration of uterine contractions increased in all women receiving the drug, uterine tone usually rising first, with a change in contractions as a secondary effect which lasted for the rest of the observation period. Uterine activity did not change in the controls. These results suggest that TGLVP might be used for the induction of abortion during the first trimester of pregnancy.


Aminotic fluid levels of 5-hydroxytryptamine and 5-hydroxyndoleacetic acid before and during labour. Levels of 5-hydroxytryptamine (5-HT) and 5-hydroxyindoleacetic acid (5-HIAA) were measured in amniotic fluid obtained at membrane rupture during labour and at amniotomy before the onset of labour. The levels of both 5-HT and 5-HIAA were higher during labour. The implications of this finding are discussed.


The prognostic value in threatened abortion of plasma progesterone values and the cornification index of vaginal smears. The predictive values of plasma progesterone levels in 70 patients threatening to abort was investigated. It was found that no patient aborted whosed plasma progesterone level remanined above 35 nmol/l between 7 and 16 weeks of pregnancy, whereas if the plasma progesterone level was less than this, subsequent abortion always occurred. The predictive value of cornification index in vaginal smears was also examined: many smears were unsatisfactory for assessment and in patients with threatened abortion there was a 14 per cent incidence of falsely optimistic and 29 per cent of falsely pessimistic predictions.


Comparison of oral and intravenous glucose tolerance tests in the diagnosis of diabetes in pregnancy. Forty potentially diabetic patients in the third trimester of pregnancy had an oral glucose tolerance test (OGTT)) and an intravenous glucose tolerance test (IVGTT); in only three were both test "diabetic". Of the 21 patients with a normal OGTT, 9 were "borderline" and 3 "diabetic" when tested by an IVGTT. Patients with an abnormal IVGTT but a normal OGTT were left untreated and allowed to go into labour spontaneously with a favourable outcome. There were no convincing relations between the results of the GTTs and levels of insulin, HPL or cortisol.


Production of fibrinolytic enzymes by macrophages on intrauterine contraceptive devices. Intrauterine contraceptive devices (IUCDs) were removed from 44 patients with a variety of clinical conditions, and incubated in culture media. Following incubation for up to 96 hours the total numbers of macrophages on each device were counted. The Lippes loop and Saf-T- Coil had higher counts than the Copper 7. The counts on all devices were higher at mid-cycle and during menstruation and significantly higher in patients with menorrhagia and intermenstrual bleeding (P less than 0.0005). Samples of culture media were taken on a number of occasions for up to 96 hours for fibrinolytic studies, and fibrinolytic activity increased with time in 10 of 16 cases where fibrinolytic activity was detected. There was a weak positive correlation between the number of cells on each of the 10 devices which produced a rise in fibrinolytic activity and the highest level of activity produced by each of the devices (r = +0.59; P less than 0.05). Plasminogen activator activity was maximum early in the incubation period, while plasmin-like activity predominated in later samples. The possible role of macrophages in IUCDs in causing menorrhagia is discussed.


Rapid enlargement of carniopharyngioma in pregnancy. A patient is described in whom rapid enlargement of a craniopharyngioma during pregnancy caused visual disturbance. The tumour was removed at 29 weeks gestation and the patient went on to have a spontaneous labour and vaginal delivery at term.


Effects of various concentrations of diethylcarbamazine citrate applied as eye drops in ocular onchocerciasis, and the possibilities of improved therapy from continuous non-pulsed delivery. Diethylcarbamazine was given as eye drops in varying concentrations in a half-log dilution series from 1.0 to 0.0001% to patients with ocular onchocerciasis. Migration of microfilariae into the cornea, followed by their straightening and disintegration, was observed with delivery rates as low as 0.1 microgram/hour. Dose-related adverse inflammatory reactions, including the development of globular limbal infiltrates with itching and redness, were seen with delivery rates as low as 0.6 microgram/hour, but substantial inflammatory reactions, including severe vasculitis, were seen only with delivery rates of or above 1.0 microgram/hour. This suggests that it should be possible to achieve beneficial clearing of the microfilarial load, without adverse reactions, by continuous non-pulsed delivery of the drug. Technology exists for such delivery, either directly into the eye or systemically by a transdermal system that could give 3 to 7 days' treatment from each application. The observations reported suggest that after preliminary clearing of the microfilarial load by carefully controlled delivery of DEC it may be possible to maintain therapy by less strictly controlled delivery in DEC-medicated salt, or to use treatment with suramin, without incurring substantial adverse reactions, such as a deterioration in vision in cases in which the optic nerve is already compromised. Continuous non-pulsed DEC delivery systems could have a place in the management of onchocercal sclerosing keratitis. The unique opportunities for using the ocular model to define the requirements for beneficial non-damaging therapy with DEC should be explored in further field trials.


Evaluation of microfilaricidal effects in the cornea from topically applied drugs in ocular onchocerciasis: Trials with levamisole and mebendazole. Increasing concentrations of levamisole and of mebendazole were applied to 1 eye in groups of 4 patients with ocular onchocerciasis in northern Cameroon. No effect resulted from up to 3.0% mebendazole suspensions, but 3.0% levamisole solutions rapidly caused entry of microfilariae, straightening out and subsequent opacification of previously curled-up living microfilariae, the rapid formation of typical limbal globular infiltrates, and the subsequent formation of fluffy opacities around the microfilariae. These changes are typical of all other drugs so far studied that have a microfilaricidal action on O. volvulus--diethlycarbamizine citrate (DEC), suramin, and metrifonate. The efficacy of 3.0% levamisole approximated to that of 0.03% DEC. This is in keeping with published observations on the filaricidal activity of these 2 compounds. It is suggested that this system of drug testing should be considered for systematic use in the search for more effective and safer drugs for onchocerciasis.


Further observations on the relationship between ocular onchocerciasis and the head nodule, and on the possible benefit of nodulectomy. From the examination of 197 patients who presented with one or more head nodules in the Sudan savanna in Cameroon, and from previous examinations of patients with ocular onchoceriasis, it concluded that in this part of Africa the formation of a head nodule is often preceded by the development of ocular lesions. Head nodulectomy is therefore of limited prophylactic value. Head nodules were removed from 107 of these patients, of whom 17 also received diethyl-carbamazine citrate (DEC), and 20 received both DEC and suramin. Fifteen other patients received DEC as the only treatment, and 4 suramin alone, while 5 received both DEC and suramin. From the follow-up examinations at 9, 12, and 24 months after treatment it was concluded that removal of the head nodule was of some benefit to lesions of the anterior segment, but that the procedure should be combined with efficient micro- and macrofilaricidal therapy in patients at risk of developing ocular pathology, that is, those with 15 or more microfilariae per skin snip near the outer canthus. This index can be measured by paramedical personnel and is therefore of great public health importance in the early detection of "at risk" patients.


Aspects of corneal changes in onchocerciasis. The distribution of living and dead microfilariae in 160 cases of ocular onchocerciasis has been studied. A model for coding the densities in 9 different areas of the cornea has been used. The average numbers of microfilariae and onchocercal punctate opacities per square millimetre were assessed. The highest densities were found in the superficial one-third of the corneal stroma at the periphery of the nasal and temporal parts of the cornea. Sclerosing  keratitis was also recorded, and the average age of the patients in this group was significantly higher than in the group with non-sclerosing onchocercal involvement. Corneal thickness measurement showed that the presence of microfilariae or onchocercal punctate opacities or a faint uveitis did not influence the values. In sclerosed areas the corneal thickness varied greatly and was dependent on the degree of the vascularisation. The routes of entry of microfilariae into the eye are discussed on the basis of the distribution patterns of microfilariae and onchocercal opacities.


Visual field defects in onchocerciasis.

Visual field defects in onchocerciasis. Lesions in the posterior segment of the eye in onchocerciasis may give visual field defects, but so far no detailed investigation has been done to determine the functional visual loss. Examination of the visual fields in 18 selected cases of onchocerciasis by means of a tangent screen test revealed important visual field defects associated with lesions in the posterior segment of the eye. Involvement of the optic nerve seemed to be important, giving rise to severely constricted visual fields. Cases of postneuritic optic atrophy showed a very uniform pattern of almost completely constricted visual fields, with only 5 to 10 degree central rest spared. Papillitis gave a similar severe constriction of the visual fields. The pattern of visual fields associated with optic neuropathy in onchocerciasis indicates that a progressive lesion of the optic nerve from the periphery may be responsible for the loss of vision. The visual field defects in onchocerciasis constitute a serious handicap, which must be taken into consideration when estimating the socioeconomic importance of the disease.


Two special indications for intraocular lens implantation. Two cases with special indications for intraocular lens implants are presented. The first case was of a 60-year-old monocular patient with congenital absence of the external nose and multiple limb deformities. The second case was of a young Bedouin girl with bilateral developmental cataracts who had poor living conditions and social objections to wearing spectacles. Intraocular lenses restored good vision.


Early postoperative sterile hypopyons.

Early postoperative sterile hypopyons. 266 eyes were examined by the slit lamp 24 hours after uncomplicated intracapsular cataract extraction. An unexpectedly high incidence of 15% macroscopic hypopyons was found with a further 13% showing a trace. Possible aetiological irritative factors were investigated by individual exclusion, but did not materially alter the incidence. All the hypopyons spontaneously and rapidly regressed without specific treatment. The suggested explanation of hypopyon production is that operative plasmoid aqueous production, inflammatory reaction, and hyphaema, coupled with early mobilisation, allow gravitational sedimenting out of blood constituents, so that white cells will fall late, forming a layer above other blood constituents.


Depth of anterior chamber after cataract extraction. A total of 80 patients with senile cataract had the anterior eye chamber depth measured optically by means of Haag-Streit's attachment II. The distance to the pupillary border was 2.59 +/- 0.05 mm (mean +/- SEM) preoperatively. It increased gradually after cataract extraction to 3.33 +/- 0.04 mm, measured 4 months after the operation. The increase of depth was the greatest in patients with a flat chamber and in elderly patients. The central chamber depth decreased gradually after the operation (from 2.82 +/- 0.05 mm preoperatively to 1.95 +/- 0.13 mm 4 months postoperatively). The number of vitreous prolapse cases rose from 68 to 87.5% in 4 months. These altered chamber depths were observed to bear no relation to postoperative corneal oedema (neither of parenchyma nor of epithelium), intraocular pressure, or bleeding into the chamber.


Dural arterio-venous malformations involving the cavernous sinus: a case report. A case of dural arteriovenous malformation involving the cavernous sinus is reported. The patient was successfully treated with selective embolisation of the fistula. These patients constitute a distinct neuro-ophthalmological syndrome which may be very difficult to diagnose clinically because of the subtle signs and symptoms they present with. Angiography is necessary to make diagnosis and to differentiate these patients from those with the more common carotidcavernous fistulae.


Dural arteriovenous fistula and spontaneous choroidal detachment: new cause of an old disease. A case is presented in which bilateral spontaneous choroidal detachments appear to be the direce result of bilateral dural arteriovenous fistula of the cavernous sinus region. Rapid resolution of the clinical signs followed bilateral orbital decompression via the transfrontal approach. Similarities in clinical presentation of both entities are reviewed and a premise for their cause-and-effect relationship elaborated. A literature search for similar unrecognised cases is discussed. The paper suggests that this association may be more frequent than published reports would imply.


Waardenburg syndrome with a fixed dilated pupil. An unusual case of Waardenburg syndrome associated with a detailed and fixed pupil of the lighter eye is described. Pharmacological investigations were performed to localise the site of the pupillary lesion. A lack of cholinergic reactivity was demonstrated, possibly due to congenital agenesis of the sphincter pupillae. Sympathetic activity was not impaired. Spiral ganglion agenesis and midline congenital anomalies are common features in Waardenburg syndrome. These lesions as well as the fixed dilated pupil might be due to an embryonal inductive failure.


Edge-light pupil cycle time.

Edge-light pupil cycle time. A thin slit-lamp beam illuminating the pupil margin produces clearly visible pupil oscillations. These oscillations can be timed with a stopwatch, thus producing a measurement of the "edge-light"  pupil cycle time'. The pupil cycle time is remarkably stable in various testing situations and is repeatable within about +/- 3% over extended periods of time. Expected normal distribution and 95% confidence intervals are given in Table 3. When the iris muscles are normally innervated and responsive, the pupil cycle time is dependent on the speed of nerve conduction and the number and strength of optic nerve impulses. Only 5% of normal persons aged 12 to 50 years are expected to have a pupil cycle time in either eye longer than 954 ms or a difference in pupil cycle time between the two eyes longer than 70 ms.


Size and shape of the model lipoprotein complex formed between glucagon and dimyristoylglycerophosphocholine. Glucagon forms water-soluble lipoprotein particles with dimyristoylglycerophosphocholine at temperatures below the phase-transition temperature of the lipid. The shape and size of this lipoprotein particle were studied by viscometry, sedimentation velocity, sedimentation equilibrium, quasielastic light scattering, and electron microscopy using both negative-staining and freeze-fracture techniques. The lipoprotein particle has an oblate ellipsoid shape with dimensions of 250 X 70  A and an approximate molecular weight of 1.4 X 106. This molecular weight is similar to that found for small unilamellar phospholipid vesicles but is achieved in the presence of glucagon without sonication. The shape of the glucagon lipoprotein particle is similar to that found for the complex formed between some serum apolipoproteins and dimyristoylglycerophosphocholine. From these data, a model for the glucagon-dimyristoylglycerophosphocholine is proposed consisting of a single bilayer of phospholipid with the glucagon incorporated into the bilayer structure in such a manner as not greatly to disturb the average area occupied per phospholipid molecule.


Properties of radiolabeled alpha-bungarotoxin derivatives and their interaction with nicotinic acetylcholine receptors. Column-purified monoiodinated, diiodinated, and tritiated derivatives of alpha-bungarotoxin (alpha-Bgt) are distinguished on the basis of their ultraviolet absorption and circular dichroism (CD) spectra. The pattern of changes in CD spectra on incorporation of iodine into a single tyrosine residue of alpha-Bgt and the widespread wavelength distribution of these effects are interpreted as reflecting primary chemical modification of the tyrosine chromophore as well as vicinal and global secondary structural changes. Native and tritiated alpha-Bgt are shown to be more effective than iodinated alpha-Bgt derivatives in competing for specific toxin binding sites on putative nicotinic acetylcholine receptors (nAChR) derived from rat brain reflecting functional perturbation of the modified toxin. In contrast, both membrane-bound and solubilized nAChR from Torpedo californica electroplax display little or no specific binding preference for native toxin, nor are there significant differences in lethal potency of alpha-Bgt derivatives toward mice. These results suggest that peripheral and putative central nAChR may differ in their alpha-Bgt binding properties and suggest the usefulness of modified toxin in detecting those subtle differences.


Investigation of the shape and size of myosin subfragment 1 using small-angle X-ray scattering. Measurement of x-ray scattering at very small angles by solutions of myosin subfragment 1 (S1) yields a radius of gyration of 3.24 nm (mean) +/- 0.03 nm (standard error for N = 9). If S1 is assumed to be ellipsoid of revolution, of uniform electron density, with a molecular weight of 1.15 X 10(5) and a partial specific volume of 0.73 cm3 g-1, then the axial ratio of the ellipsoid is 2.89 +/- 0.06 (prolate) or 0.26 +/- 0.01 (oblate), and the major axis is 13.0 +/- 0.2 nm (prolate) or 10.1 +/- 0.1 nm (oblate). Measurements at larger angles allow models of S1 morphology to be tested; theoretical scattering curves for various ellipsoids of revolution were calculated. The observed scatterina can be approximated by the scattering from ellipsoids with axial ratio 2.0 to 3.0 (prolate), or 0.25 to 0.4 (oblate). Models that fit the data over the range of scattering angles from 0 to 30 mrad are: prolate ellipsoid with axial ratio 2.3, major axis 12 nm; and oblate ellipsoid with axial ratio 0.4 and major axis 10 nm. Thus analyses of two parts of the scattering curve, by different methods, indicate that S1 is fae from spherical, and that its morphology may be approximated by ellipsoids of the aforesaid dimensions.


Highly active position eight analogues of somatostatin and separation of peptide diastereomers by partition chromatography. Six stereochemically pure analogues of somatostatin (SS), D- and L-5F-Trp8-SS, D- and L -6F-Trp8-SS, and D- and L-5Br-Trp8-SS, were synthesized and found to be more potent than somatostatin in suppressing the release of growth hormone from cultured rat pituitary cells. Two of the analogues, D-5F-Trp8- and D-5Br-Trp8-SS, were respectively 25 and 30 times more active than somatostatin in that assay. The analogues were prepared by solid phase synthesis of their corresponding diastereomeric mixtures, followed by their complete resolution by preparative partition chromatography. Reversed phase high pressure liquid chromatography (HPLC) was used to monitor the resolution and also to check the final purity of each peptide. Positive identification of each diastereoisomer was determined by amino acid analyses of their enzymatic digests, direct comparison with a known all-L standard in the case of the 5F-Trp8 analogues, and chromatographic separation of dansylated amino acids following enzymatic digestion of D- and L-5Br-Trp8-SS. The role of tryptophan in somatostatin is discussed and it is suggested that maintenance of physiological activity in somatostatin peptides, at least on the pituitary, is partially dependent upon the degree of resonance in the indole nucleus in position 8.


Sites of phosphorylation on pyruvate dehydrogenase from bovine kidney and heart. The highly purfied pyruvate dehydrogenase complex (EC 1.2.4.1) and uncomplexed pyruvate dehydrogenase from bovine kidney and heart mitochondria were phosphorylated and inactivated with pyruvate dehydrogenase kinase and [gamma-32P]ATP. Tryptic digestion of the phosphorylated pyruvate dehydrogenase yielded three phosphopeptides, a mono- (site 1) and a di- (sites 1 and 2) phosphorylated tetradecapeptide and a monophosphorylated nonapeptide (site 3). The amino acid sequences of the three phosphopeptides were established to be Tyr-His-Gly-His-Ser(P)-Met-Ser-Asn-Pro-Gly-Val-Ser-Tyr-Arg, Tyr-His-Gly-His-Ser(P)-Met-Ser-Asn-Pro-Gly-Val-Ser(P)-Tyr-Arg, and Tyr-Gly-Met-Gly-Thr-Ser(P)-Val-Glu-Arg. Phosphorylation proceeded markedly faster at site 1 than at sites 2 and 3, and phosphorylation at site 1 correlated closely with inactivation of pyruvate dehydrogenase. Complete inactivation of pyruvate dehydrogenase was associated with incorporation at site 1 of 1.0--1.6 mol of phosphoryl groups per mol of enzyme. Since pyruvate dehydrogenase is a tetramer (alpha2beta2) and since phosphorylation occurs only on the alpha subunit, the possibility of half-site reactivity is considered.


Nuclear magnetic resonance studies of 6-hydroxydopamine and its interactions with SH-containing model compounds. Evaluation of possible mechanism for neurocytotoxicity. 6-Hydroxydopamine (I) is a well-known neurocytotoxic agent which has become an important tool in many neurochemical studies in recent years. Biochemical investigations of the mechanism of action of 6-hydroxydopamine indicated that this amine binds covalently and irreversibly to proteins. In the present work, molecular properties of 6-hydroxydopamine in aqueous solution such as self-association, ionization, intramolecular conformations, and possible cyclization were investigated using 1H nuclear magnetic resonance spectroscopy. A model study for the interaction of 6-hydroxydopamine with proteins was undertaken by using SH-containing molecules: cysteine, glutathione, and bovine serum albumin. The binding of these compounds to 6-hydroxydopamine was found to cause labilization of the hydrogen attached to C2 of the amine aromatic ring. This effect was interpreted in  terms of nucleophilic attack of RS- on C1 of 6-hydroxydopamine. A proposed model for neurocytotoxicity is discussed.


1 alpha-hydroxy-25-fluorovitamin D3: a potent analogue of 1 alpha,25-dihydroxyvitamin D3. Chemically synthesized 1 alpha-hydroxy-25-fluorovitamin D3 was compared to 1,25-dihydroxyvitamin D3 for potency in the chick intestinal cytosol-binding protein assay, induction of intestinal calcium transport, mobilization of calcium from bone, and epiphyseal plate calcification in the rat. The 25-fluorinated analogue causes 50% displacement of 1,25-dihydroxy[23,24-3H]D3 at 1.8 X 10(-8) M in the competitive protein-binding assay, whereas only 5.6 X 10(-11) M of unlabeled 1,25-dihydroxyvitamin D3 is needed for equal competition. This 315-fold difference between and 1 alpha-hydroxy-25-fluorovitamin D3 indicates that the fluoro analogue is about equipotent with 1 alpha-hydroxyvitamin D3 in the protein-binding assay. However, 1 alpha-hydroxy-25-fluorovitamin D3 is 1/50 as active as 1,25-dihydroxyvitamin D3 in vivo in the stimulation of intestinal calcium transport and bone calcium mobilization in vitamin D deficient rats on a low-calcium diet. Likewise, 1 alpha-hydroxy-25-fluorovitamin D3 is about 40 times less active than 1,25-dihydroxyvitamin D3 in inducing endochondrial calcification in rachitic rats. No selective actions of 1alpha-hydroxy-25-fluorovitamin D3 were noted. Since the 25 position of the analogue is blocked by a fluorine atom, it appears that 25-hydroxylation of 1 alpha-hydroxylated vitamin D compounds in vivo is not an obligatory requirement for appreciable vitamin D activity.


Phase behavior of synthetic phosphatidylglycerols and binary mixtures with phosphatidylcholines in the presence and absence of calcium ions. Using differential thermal analysis, scanning calorimetry and light scattering, transition temperatures and enthalpy data for the gel to liquid crystalline phase transitions of five synthetic phosphatidylglycerol sodium salts (PG-Na+) were measured. The  values obtained were almost identical with literature values for the corresponding phosphatidylcholines (PC). However, transition temperatures for the fully protonated forms of the saturated phosphatidylglycerols (PG-H+) were approximately 20 degrees C higher. For binary mixtures of PG-Na+ and PC in which the acyl chains of the two species were identical, the width of the thermal transition for the phase change was not appreciably greater than that observed with either of the two components alone. In contrast, mixing of PG-Na+ and PC with different chain lengths increases the transition width. In the presence of Ca2+, narrow transitions were also observed with mixtures of PG and PC when the chain length of the PG-Ca2+ was equal to or two carbons shorter than the PC but the transition width was clearly increased when the chain length of the PG-Ca2+ was two carbons longer than the PC. Mixing lipids with greater differences in chain length or mixing saturated lipids with unsaturated lipids in the presence of Ca2+ produced two minima in the thermograms, clearly indicative of phase separation. In sum, these results provide evidence for a high degree of miscibility of the phosphoglycerol and phosphocholine head groups, either in the presence or absence of Ca2+, such that the characteristic phase behavior of each mixture is determined primarily by differences in the hydrocarbon chain structure.


Ligand-induced conformation changes in Torpedo californica membrane-bound acetylcholine receptor. A time-dependent increase in ligand affinity has been studied in cholinergic ligand binding to Torpedocalifornica acetylcholine receptor by inhibition of the kinetics of of [125I]-alpha-bungarotoxin-receptor complex formation. The conversion of the acetylcholine receptor from low to high affinity form was induced by both agonists and antagonists of acetylcholine and was reversible upon removal of the ligand. The slow ligand induced affinity change in vitro resembled electrophysiological desensitization observed at the neuromuscular junction and described by a two-state model (Katz, B., & Thesleff, S. (1957) J. Physiol. 138, 63). A quantitative treatment of the rate and equilibrium constants determined for binding of the agonist carbamoylcholine to membrane bound acetylcholine receptor indicated that the two-state model is not compatible with the in vitro results.


Photogenerated reagents for membrane labeling. 1. Phenylnitrene formed within the lipid bilayer. Phenylnitrene generated photochemically from phenyl azide that is bound to artificial phospholipid vesicles labels the fatty acid chains of the lipids in low yield. The labeling yield varies from approximately 3.3% with soybean lecithin (which is highly unsaturated) to approximately 0.25% with dimyristoyllecithin (which is completely saturated). Labeling is largely eliminated by reduced glutathione in the aqueous phase. Nitrenes are evidently unsatisfactory reagents for the labeling either of lipids or by analogy of the hydrophobic portions of membrane proteins. This is mainly because the long lifetimes and electrophilic character of nitrenes will lead to the preferential labeling of extrinsic membrane components. Phenyl azide itself is further compromised as a lipophilic reagent by its rather low partition coefficient into lipid bilayers, as measured by equilibrium dialysis.


Photogenerated reagents for membrane labeling. 2. Phenylcarbene and adamantylidene formed within the lipid bilayer. Phenylcarbene and adamantylidene have been generated photochemically from the corresponding diazirines within lipid bilayers. Reasonable yields of labeled fatty acid side chains have been observed. The products have been characterized by gas chromatography-mass spectrometry  and derive both from the insertion of the carbene into carbon-hydrogen bonds of saturated fatty acids and from the addition of the carbene to the carbon-carbon double bonds of unsaturated fatty acids. In contrast to the results found using phenylnitrene, the lipid labeling by carbene is not reduced by the water-soluble scavenger glutath ione. Carbenes generated from diazirines are evidently superior reagents for the photolabeling of lipids and should be useful for identifying the intrinsic hydrophobic sections of membrane proteins.


Resonance Raman studies of bovine metarhodopsin I and metarhodopsin II. The resonance Raman spectra of bovine metarhodopsin I and metarhodopsin II have been measured. The spectra are compared with model chromophore resonance Raman data. It was found that metarhodopsin I is linked to opsin via a protonated Schiff base linkage, whereas metarhodopsin II is linked by an unprotonated Schiff base. A recent suggestion that the chromophore of metarhodopsin II is retinal is explicitly disproved. The chromophores of both metarhodopsins are found to have an essentially all-trans conformation. The basic mechanism for color regulation in both forms appears to be electron delocalization. The data tend to support the model of cis-trans isomerization as the primary mechanism for vision. Also, the conclusions and inferences of this work on energy uses and storage by rhodopsin in neural generation are discussed.


Altered aminoacyl-tRNA synthetase complexes in G1-arrested Chinese hamster ovary cells. Aminoacyl-tRNA SYNTHETASE COMPLEXES EXISTING IN Chinese hamster ovary (CHO) cells were shown to undergo alterations as a function of the growth state of the cell. The distribution pattern for 13 particulate postribosomal aminoacyl-tRNA synthetases in 10-30% (w/v) exponential sucrose gradients was determined for the enzymes from CHO cells as they exist under three different culture conditions: exponential growth, G1 arrest induced by isoleucine deficiency, and G1 arrest induced by leucine deficiency. The synthetases specific for the amino acids Arg, Asp, Cys, Gln, His, Lys, Met, Thr, and Val have indistinguishable distribution patterns in all three cell types. However, the synthetases specific for Glu, Pro, Leu, and Ile have a unique distribution of synthetase forms in the G1-arrested cultures and this distribution is independent of whether G1 arrest was induced by isoleucine or leucine deficiency. The distribution of synthetase forms in G1-arrested cells differs in a definite, reproducible manner from the profiles obtained with the exponentially growing cells, and this fact is strong evidence for an in vivo role for the synthetase complexes.


Structure of methemerythrin at 2.8-Angstrom resolution: computer graphics fit of an averaged electron density map. The crystal structure of methemerythrin from Themiste dyscritum has been determined at 2.8-Angstrom resolution by single isomorphous replacement technique combined with anomalous scattering from a K2HgI4 derivative. Noncrystallographic symmetry relating the four subunits in the asymmetric unit was used to obtain an average electron density map of the hemerythrin monomer, and a computer graphics system was used to fit a polypeptide model to the electron density. The average map was of sufficient quality to locate most of the amino acid side chains and to confirm the assignment of His-25, His-54, Glu-58, His-73, His-77, His-101, Asp-106, and Tyr-109 as the iron ligands. One of the mercury sites in the heavy atom derivative is located between two Cys-9 residues related by a noncrystallographic twofold axis, although no intersubunit disulfide bond is present in the native structure. The residues responsible for the binding of the subunits to form the octamer are identified.


Assignment of the 13C nuclear magnetic resonance spectrum of aqueous ganglioside GM1 micelles. This article describes the natural-abundance Fourier-transform carbon-13 nuclear magnetic resonance spectrum, at 67.88 MHz, of aqueous micelles of bovine brain ganglioside GM1 of purity greater than 99%. Assignments are given for every carbon nucleus in the molecule, on the basis of a comprehensive study of the relevant mono-, di-, tri-, and polysaccharides, including several containing sialic acid (5-acetamido-3, 5-dideoxy-D-glycero-D-galacto-nonulopyranosonic acid), and phospho-, sphingo-, and glycosphingolipids. These assignments represent an extension of the 13C nuclear magnetic resonance data from monosaccharides and lipids to complex oligosaccharides and glycolipids. They also form the basis for interpretation of spectral perturbations induced in GM1 by titration with paramagnetic europium(III). The single sialic acid in GM1 was found to be alpha-glycosidically linked in the oligosaccharide from considerations of its unique anomeric chemical shift. The sialic acid carboxyl and glyceryl side chain, along with additional ligands donated by the 2-acetamido-2-deoxy-beta-D-galactopyranoside and terminal beta-D-galactopyranoside residues in the oligosaccharide portion of GM1, were found to be intimately involved with cation binding. It is proposed that the higher affinity, compared with monomeric sialic acid, of GM1 for cations may result from these additional oligosaccharide groups, which may effectively compete for water ligands in the metal cation coordination sphere.


Glutathione-facilitated refolding of reduced, denatured bovine seminal ribonuclease: kinetics and characterization of products. Totally reduced and denatured seminal ribonuclease was regenerated using the glutathione redox system. The refolding kinetics of the enzyme were determined as a function of redox state, temperature from 14 to 43 degrees C, pH, and protein concentration. The maximal rate of regeneration occurred with 3 x 10(-3) M reduced glutathione, 6 x 10(-4) M oxidized glutathione, 24 to 30 degrees C, and pH 8.2. The products of the refolding process were characterized by Sephadex G-75, sodium dodecyl sulfate gel electrophoresis, enzymatic activity, circular dichroism, and amino acid analysis. The results indicate that the native dimeric form of the enzyme is not produced during refolding to any appreciable extent; rather, the major product is monomeric. The purified monomer exhibits twice the activity of the native enzyme toward yeast RNA. Its circular dichroism spectrum is different from the native enzyme and is quite similar to that of pancreatic ribonuclease A. Amino acid analyses showed that two glutathione molecules are bound to the monomer, suggesting that cysteine-31 and -32, which normally form the intermolecular disulfide bonds, are blocked.


Identification of the catalytic site of rat liver glutathione peroxidase as selenocysteine. A procedure was developed to isolate 75Se-labeled rat liver glutathione peroxidase (glutathione:H2O2 oxidoreductase, EC 1.11.1.9) at 30--50% purity with 20--30% yields in 4--5 days. Using these preparations of glutathione peroxidase, the selenium moiety in the enzyme was identified as selenocysteine by derivatizing the seleno group with either iodoacetate or ethylenimine in the intact protein, hydrolyzing the protein with 6 N HCl, and cochromatographing the 75Se-labeled products with known standards. Techniques employed were anion-exchange chromatography, cation-exchange chromatography, gel-permeation chromatography, two-dimensional thin-layer chromatography, and automated amino acid analysis. The selenocysteine moiety was identified as the catalytic site in glutathione peroxidase by specifically labeling the enzyme with [14C]iodoacetate on the 75Se-labeled selenium atom and fractionating the 14C, 75Se-labeled derivative after acid hydrolysis. It was concluded that the reduced form of glutathione peroxidase contains the selenocysteine selenol (-SeH) at the catalytic site.


Activation of bovine factor X (Stuart factor)--analogy with pancreatic zymogen-enzyme systems. The activation of bovine coagulation factor X has been studied by kinetic and spectrophotometric measurements. The pH dependence of the hydrolysis of specific ester substrates by activated factor Xa can be ascribed to two independently ionizing groups with pKa values of 6.9 and 8.8, respectively. The rates of reaction of factor X, before and after activation, with the active-site titrant methanesulfonyl fluoride, suggest that the reactivity of the active-site serine residue in factor X is similar to that in trypsinogen and in factor Xa similar to that in trypsin. Analogous comparisons using diisopropyl phosphofluoridate as the titrant suggest that a hydrophobic binding site is absent in both the enzyme and zymogen. This conclusion is consistent with the lack of change in circular dichroism when acyl derivatives of factor V are converted to their acyl enzyme counterparts.


Purification and characterization of dimethylallyl pyrophosphate: aspulvinone dimethylallyltransferase from Aspergillus terreus. Dimethylallyl pyrophosphate:aspulvinone dimethylallyltransferase, the prenylation enzyme for the biosynthesis of aspulvinone pigments, has been purified from mycelia of Aspergillus terreus. The transferase catalyzed the transfer of the dimethylallyl moiety from dimethylallyl pyrophosphate to either of the two aromatic rings of aspulvinone E to give the mono- and diprenylated derivatives which were identified with the metabolites aspulvinone I and aspulvinone H, respectively. Aspulvinone G, another fundamental metabolite of this series, also acted as substrate to afford the corresponding diprenylated derivative, which is assumed to be a precursor for aspulvinone C, D, and F. The molecular weight of the enzyme was estimated to be 240 000--270 000 by gel filtration. Since the subunit molecular weight determined by NaDodSO4-polyacrylamide disc gel electrophoresis was 45 000, the native enzyme appears to be a hexomeric protein composed of identical molecular weight subunits. The apparent Km values for aspulvinone E, aspulvinone G, and dimethylallyl pyrophosphate were 13.7, 7.7, and 40.0 micron, respectively. The enzyme shows the maximum activity at pH 7.0, and no metal ion is necessary for the activation. Sulfhydryl blocking agents or mercaptoethanol has no effect. Bromophenol blue binds specifically to the transferase and strongly inhibits the enzyme activity.


Properties and the locations of a set of fluorescent probes sensitive to the fluidity gradient of the lipid bilayer. The synthesis and properties of a set of four fluorescent probes (n-(9-anthroyloxy) fatty acids, n = 2, 6, 9, 12) sensitive to the fluidity gradient of the lipid bilayer are described. Fluorescent quenching experiments show that the probes locate at a graded series of depths in the bilayer. A fifth probe, methyl-9-anthroate, locates near the bilayer centre. As an example of their application, the probes are used to study the phase transitions of dipalmitoyl phosphatidyl-choline. Changes in the rotational relaxation times of the probes across the transitions are more pronounced at the centre of the bilayer than at the surface.


Photodynamic effects of protoporphyrin on human erythrocytes. Nature of the cross-linking of membrane proteins. Protoporphyrin-sensitized photooxidation in human red blood cell membranes leads to severe deterioration of membrane structure and function. The membrane damage is caused by direct oxidation of amino acid residues, with subsequent cross-linking of membrane proteins. The chemical nature of these cross-links was studied in model systems, isolated spectrin and red cell ghosts. Cysteine and methionine are not involved in the cross-linking reaction. Further it could be shown that dityrosine formation, the crucial mechanism in oxidative cross-linking of proteins by peroxidase-H2O2 treatment, plays no role in photodynamic cross-linking. Experimental evidence indicated that a secondary reaction between free amino groups and a photooxidation product of histidine, tyrosine or tryptophan is involved in photodynamic cross-linking. This was deduced from the reaction observed between compounds containing a free amino group and photooxidation products of these amino acids, both in model systems, isolated spectrin and erythrocyte ghosts. In accordance, succinylation of free amino groups of membrane proteins or addition of compounds with free amino groups protected against cross-linking. Quantitative data and consideration of the reaction mechanisms of photodynamic oxidation of amino acids make it highly probable that an oxidation product of histidine rather than of tyrosine or tryptophan is involved in the cross-linking reaction, via a nucleophilic addition by free amino groups.


Purification and characterization of chick intestine brush border membrane. Effects of 1alpha(OH) vitamin D3 treatment. A new technique has been developed for the isolation of membrane vesicles from the vitamin D-deficient and vitamin D-treated chick intestinal brush border membrane. The technique involves removal of nuclei from a low speed pellet by discontinuous sucrose gradient centrifugation. The resulting intact brush borders are then homogenized in 0.5 M Tris and the membrane fragments purified on a glycerol gradient. This preparation represents a 20-fold purification of the brush border marker sucrase. After 1alpha-hydroxyvitamin D3 treatment there is a significant increase in membrane phospholipid phosphorous, an alteration in the fatty acid composition of the phosphatidylcholine fraction of membrane phospholipid, and a decrease in sucrase specific activity.


Topographic studies of glycoproteins of intact synaptosomes from rat brain cortex. Glycoproteins in the external surface of intact synaptosomes from rat brain cortex have been studied by oxidation of exposed galactose and galactosamine groups by galactose oxidase followed by reduction with labeled sodium borohydride. Purified synaptosomes were labeled, disrupted by osmotic shock, and the particulate components were fractionated on diatrizoate to give four synaptosomal membrane fractions (A to D) and a mitochondrial pellet (E). Fractions A and B represent highly purified synaptosomal plasma membranes. After separation of their polypeptides by electrophoresis, 4/5 of the label was present in two bands: one about 72 000 and the other between 7800 and 3200 daltons. Seven other bands were labeled to various degrees: 160 000, 96 000, 53 000, 39 000, 34 000, 23 000 and 16 000 daltons. With isolated membranes (which incorporate 5--6 times more label) 4/5 of label was present in polypeptides in three ranges: 160 000--96 000, 70 000--40 000 and 7800--3200. The number of polypeptides that can be labeled by treatment of isolated membranes is very large. In comparison, glycoproteins whose topographical distribution permits interaction with large molecules at the synpatic surface are very limited. It is further suggested that the external synaptosome membrane involves a relatively tight network of interacting molecules that cannot be readily penetrated by large molecules.


Cytochalasin B inhibition and temperature dependence of 3-O-methylglucose transport in fat cells. The transport of 3-O-methylglucose in white fat cells was measured under equilibrium exchange conditions at 3-O-methylglucose concentrations up to 50 mM with a previously described method (Vinten, J., Gliemann, J. and Osterlind, K. (1976) J. Biol. Chem. 251, 794--800). Under these conditions the main part of the transport was inhibitable by cytochalasin B. The inhibition was found to be of competitive type with an inhibition constant of about 2.5 . 10(-7) M, both in the absence and in the presence of insulin (1 micrometer). The cytochalasin B-insensitive part of the 3-O-methylglucose permeability was about 2 . 10(-9) cm . s-1, and was not affected by insulin. As calculated from the maximum transport capacity, the half saturation constant and the volume/surface ratio, the maximum permeability of the fat cell membrane to 3-O-methylglucose at 37 degrees C and in the presence of insulin was 4.3 . 10(-6) cm . s-1. From the temperature dependence of the maximum transport capacity in the interval 18--37 degrees C and in the presence of insulin, an Arrhenius activation energy of 14.8 +/- 0.44 kcal/mol was found. The corresponding value was 13.9 +/- 0.89 in the absence of insulin. The half saturating concentration of 3-O-methylglucose was about 6 mM in the temperature interval used, and it was not affected by insulin, although this hormone increased the maximum transport capacity about ten-fold to 1.7 mmol . s-1 per 1 intracellular water at 37 degrees C.


On the development of glycine transport systems by rat renal cortex. The initial uptake of glycine by renal cortical slices from newborn Sprague-Dawley and Long-Evans rats is the same as that observed in adult tissues. Both newborn and adult tissue possess similar high and low affinity glycine transport systems which require an examination of velocity measurements over a wide range of concentration (0.02--50.0 mM) for their discernment. Initial rates of glycine uptake by isolated renal tubule fragments from newborn and adults are similar at a physiological substrate concentration but at high glycine levels there appears to be a decrease in velocity of uptake (V) associated with the high Km system in the young. Whatever preparation of renal cortex is studied, there is a consistent finding that immature tissue is able to accumulate much higher intracellular levels of glycine than the adult, a finding consistent with slower efflux from the cell. An interpretation of the etiology of physiologic aminoaciduria in young animals should take this into account.


Binding of lithium diiodosalicylate to glycophorin. Glycophorin was purified from human erythrocyte ghosts by the lithium diiodosalicylate -phenol procedure utilizing 125I-labeled lithium diiodosalicylate. The glycophorin preparation was found to contain 8.9 +/- 2.1 mol lithium diiodosalicylate per mol glycophorin. This bound lithium diiodosalicylate cannot be removed by extensive washings with a variety of polar organic solvents nor by treatment with the detergent, sodium deoxycholate. Further, the hydrophobic peptide produced from glycophorin by trypsin digestion contained 3.4 mol lithium diiodosalicylate per mol peptide.


Quantitative analysis of the amino-terminal residues of spectrin by use of the transamination reaction. The metal ion-catalysed transamination reaction has been examined as a means of quantitative amino-terminal analysis of proteins. Application of this method to the erythrocyte membrane protein, spectrin, showed that this protein contained a single amino-terminal residue per 240,000 daltons. This value supports the hypothesis that spectrin is comprised of two polypeptide chains of approx. 220,000 and 250,000 daltons, respectively.


beta sheet formation by L-methionine oligopeptides. Monodispersed N- and C-protected linear homo-oligomethionines (n = 2- -7) are studied by measurements of circular dichroism in the vacuum ultraviolet region. In the solid state higher members of the series take up a beta-conformation in which both parallel and antiparallel chain arrangements are present. The strong beta-forming tendency of the methionine residue is demonstrated.


Tertiary structure variability within the quaternary states of hemoglobin: a spin label study. Using variable temperature techniques, the spin label spectral resolution of hemoglobin labeled at the beta93 cysteines with N-(1-oxyl-2,2,6,6-tetramethyl-4-piperidinyl)iodonacetamide has been greatly enhanced. The effects of different ligands, inositol hexaphosphate, pH and salt concentration upon spin labeled ferrous and ferric hemoglobin indicate that the beta chain tertiary structure exhibits considerable variability within the oxy and deoxy quaternary structures. From these studies ligand and spin state changes both appear to be of significance in producing structural changes; binding of inositol hexaphosphate then produces further structural changes secondary in amplitude.


Small angle x-ray scattering studies on adenovirus type 2 hexon. Adenovirus type 2 hexons have been studied in solution by small angle X-ray scattering, and the following molecular parameters determined: radius of gyration (Rg) = 4.9 nm, molecular weight (M) = 310.000, invariant volume (Vinv) = 630 mn3, maximal distance (Dmax) = 14.5--15.5 nm. A diffraction pattern was obtained up to an angular increment of h = 2.5 nm-1. Various models for the hexon have been explored by calculating the diffraction pattern from the Debye formula for 1200 spheres arranged to define the scattering volume of each model. Models were first built according to electron micrographic results. Later, preliminary results of a crystallographic study were used for model building. The experimental pattern and the pattern resulting from the model determined by crystallographic methods were compared and showed good agreement.


X-ray diffraction effects related to superstructure in rat tail tendon collagen. A number of unusual X-ray diffraction effects concerning the meridional low angle reflections of collagen are presented which are due to structural inhomogeneities in the 100 micron range within the tendon such as are expected to be associated with the planar crimp structure of tendon units. These newly observed effects provide diffraction confirmation for such a crimped morphology. The effects consist of splitting of the reflections both azimuthally and radially. Azimuthal split varied with rotation of the tendon unit around its own axis and is directly related to the existence of the crimp, its angle and planarity. Radial splitting is a consequence of the limited sampling of the micro-structure by the collimator, which provides further support for the crimp morphology and conveys added information about the crimp form. It is shown that this limited sampling can provide a kind of "micro-X-ray topography" technique for the study of micro-textures on the appropriate dimensional level, while ti could be the source of misrepresentation if its origin remains unrecognized. The effect of stretching is examined and interpreted in terms of crimp straightening. Simultaneous examination of medium angle equatorial reflections, when combined with some electron micrographs point to further issues concerning the relation between the large scale and fibril substructure. It is believed that the present findings have general implications for structure research on collagen.


Cleavage of a specific bond in troponin C by thrombin. Limited proteolysis of rabbit skeletal troponin C with bovine thrombin yielded two fragments, TH1 (Mr = 11000) containing Ca2+ binding regions I--III and TH2 (Mr = 6000) containing region IV. Determination of the partial sequences of the fragments established the site of cleavage at Arg120-Ala121. Secondary cleavage by thrombin at other arginyl or lysyl residues in troponin C was ruled out by the sequence data and by the amino acid compositions of the two fragments.


Studies on the binding of adenylyl-3', 5'-cytidine to ribonuclease. The interaction of adenylyl-3',5'-cytidine (ApC) with ribonuclease-A (RNAase-A) was studied by steady-state kinetics and ultraviolet difference spectroscopy. X-ray difference Fourier synthesis at 4 A resolution was also used to study the binding of ApC to RNAase-S. Unlike well-studied compounds like uridylyl-3',5'-adenosine, ApC binds in an unique way: (1) the cytidine moiety is bound to the B1 and R1 sites, (2) the adenosine moiety protrudes to the solution and is not fixed spatially and (3) the phosphate group is bound to the non-specific site (the "Po site") previously postulated (Sawada, F. and Irie, M. (1969) J. Biochem. (Tokyo) 66, 415--418) as the binding site for the 5'-phosphate of uridine 2',5'-diphosphate or uridine 3',5'-diphosphate. This conclusion is consistent with that derived for adenylyl-3',5' -4-thiouridine based on CD difference spectroscopy (White, M.D., Keren-Zur, M. and Lapidot, Y. (1977) Nucleic Acid Res. 4, 843--851). The "Po site" is most likely the epsilon-amino group of Lys 66.


Human serum histidine-rich glycoprotein. I. Interactions with heme, metal ions and organic ligands. The 3.8 S alpha2-histidine-rich glycoprotein of human serum is composed of two non-identical subunits, each of which contains carbohydrate. The far ultraviolet circular dichroism spectrum of alpha2-histidine glycoprotein indicates that the protein has little alpha-helix but apparently appreciable amounts of beta-sheet and non-regular structures. alpha2-Histidine-rich glycoprotein binds heme with concomitant changes in the electrophoretic mobility of the protein, in the fluorescence of tryptophan residues, and in the absorption and optical activity of the heme chromophore. By fluorescence quenching, the stoichiometry of binding is 1 heme per alpha2-histidine-rich glycoprotein molecule with an apparent Kd near 1.5 muM; however, by changes in absorbance, the interaction of 9 to 10 additional heme molecules with the alpha protein can be detected. The absorption spectra of heme . alpha2-histidine-rich glycoprotein complexes resemble those of low-spin hemoproteins. The ellipticity induced in the heme chromophore on binding by alpha2-histidine-rich glycoprotein increases linearly up to about 10 hemes bound per mol protein. No change in the conformation of alpha2-histidine-rich glycoprotein was indicated by circular dichroism when one or two heme molecules are bound by the protein. alpha2-Histidine-rich glycoprotein does not effectively compete with human serum albumin for heme, suggesting that alpha2-histidine-rich glycoprotein has no major function in serum heme transport. Nonetheless, the binding of heme by alpha2-histidine-rich glycoprotein provides a means of studying the structure of this protein using the heme chromophore as a probe. alpha2-Histidine-rich glycoprotein also binds other organic molecules including bilirubin, diaquocobinamide, Cibacron blue F3GA and rose bengal, and certain divalent metals. It is of interest that copper, zinc, nickel, cadmium and cobalt effectively inhibit the binding of heme by alpha2-histidine-rich glycoprotein, whereas other divalent metals tested, including calcium, magnesium and manganese do not appreciably affect the heme-alpha2-histidine-rich glycoprotein interaction.


The enthalpy titration of troponin C with calcium. Microcalorimetric titrations have been used to study the binding of Ca2+ to troponin C, the Ca-binding component of troponin. Troponin C was extracted from rabbit skeletal muscle and Ca2+ was added to Ca-free troponin C in the presence of 1 mM Mg2+ at pH 8.83 at 10 degrees C. In these conditions proton exchanges of troponin C on Ca-binding are negligible. In case of troponin C there is neither aggregation nor dissociation when Ca2+ is added, a phenomenon controlled by bound Ca, which caused some difficulty in the analysis of results for troponin. Using an iterative curve fitting procedure the following parameters of two classes of Ca-binding sites have been determined from the calorimetric results: number of binding sites in 1st class, 1.81; in 2nd class, 0.69; log of binding constant in 1st class, 7; in 2nd class, 5.0; standard enthalpy change for 1st class, -10.00 kJ . mol-1; that in 2nd class, -25.64. The standard free energy and entropy changes have been calculated from these values. The results indicate that the standard entropy change for Ca2+-troponin C interaction is positive and strikingly resembles the values for the interaction of organic sequestering agents such as glycol-EDTA with Ca2+.


The presence of type III collagen in the developing tooth. Type I and type III collagens have been isolated from dental papilla and dental pulp of bovine tissues by enzymic digestion with pepsin and differential salt precipitation. Type III collagen was further purified by molecular sieve and ion-exchange chromatography. The relative proportions of type III and type I collagens were estimated by two different techniques, gel electrophoresis in the presence of mercaptoethanol, and direct estimation of the alpha1(III)CB3 peptide. Both techniques gave similar values. Type III collagen constituted 24% of papilla and 28% of pulp collagen by the first procedure, and 20% and 31% by the second. 18% of dental follicle collagen was type III.


Interaction of ovalbumin and its asparaginyl-carbohydrate fractions with concanavalin A. The interaction of ovalbumin and its asparaginyl-carbohydrate fractions with concanavalin A was studied. Relative affinities were obtained by competitive binding studies using p-nitrophenyl alpha-D-mannopyranoside. Ovalbumin was separated into two fractions, I and II, by chromatography on concanavalin A-Sepharose. Ovalbumin and its fractions I and II interacted with concanavalin A in solution with binding affinities at 10 degrees C of 2 . 10(5) M-1, 3 . 10(4) M-1 and 2 . 10(6) M-1, respectively. The seven asparaginyl-carbohydrate fractions, obtained by fractionation on Dowex 50W-X2 (H+) and Durrum DA-4 (borate)columns, bound to concanavalin A with approximately the same affinity as native ovalbumin, suggesting that the sugar residues for binding in the isolated carbohydrates are exposed in the native protein. The binding of ovalbumin to concanavalin A was minimal after treatment with alpha-D-mannosidase in spite of the fact that only one half of the available mannose residues were hydrolyzed when compared to those removed by similar treatment of the asparaginyl-carbohydrate before fractionation. It is concluded that those alpha-D-mannosyl residues in ovalbumin that are required for binding to concanavalin A are accessible to alpha-D-mannosidase while the residual mannosyl groups are "buried" from interaction with concanavalin A and the enzyme.


Purification and some properties of a lethal toxic fragment of staphylococcal alpha-toxin by tryptic digestion. Purified staphylococcal alpha-toxin (molecular weight approximately 36,000) was mildly digested with trypsin, yielding two components by sodium dodecyl sulfate-polyacrylamide gel electrophoresis. A fast-moving component (molecular weight 17,000 +/- 5%) which is relatively resistant to tryptic digestion and a slow-moving component (molecular weight 20,000 +/- 5%) which tends to aggregate. The fast-moving component was highly purified by means of combined procedures of column chromatography on Sephadex G-200 with zone electrophoresis on starch. The purified fast-moving component retained a high degree of lethal toxicity for mouse but lacked hemolytic and dermonecrotic activities, whereas the slow-moving component proved to be a nontoxic polypeptide. The lethal toxic fragment was antigenically active showing partial immunological identity with the parent alpha-toxin and stimulated the formation of antibodies capable of neutralizing the lethal action of alpha-toxin in vivo. Some physical properties and the amino acid composition of the purified lethal toxic fragment have been compared with those of native alpha-toxin.


Crystallography and oriented single crystal electron microscopy of hemoglobin deer II, a hemoglobin that exhibits matchstick-shaped erythrocytes. Deer hemoglobin beta chain type II has been crystallized and preliminary diffraction data and oriented single crystal transmission electron micrographs have been obtained. The crystals are monoclinic P21 with Z = 4. The electron micrographs show a herringbonelike structure in the ab plane with open rectangular solvent channels and a fiber-like arrangement of molecules perpendicular to this plane.


[Nature of the electron excited state in pigment redox reactions. II. Analysis of the scheme of primary processes in the photooxidation reaction of chlorophylls a and b and pheophytin a ]. A scheme of primary reactions in photooxidation of pigments was considered assuming that electron transfer processes can occur via singlet excited as well as triplet states. The results of analysis are compared with the experimental data on relative yield values of chlorophylls a, b, and pheophytin a cation-radicals, as well as with the data on fluorescence quenching. A conclusion has been drawn that photooxidation of pigments proceeds exclusively via the triplet state. The dependence of rate constant quenching values of chlorophyll a triplet state by certain electron acceptors on values of half cell potentials was given.


[Impulse photoconductance of solutions of chlorophyll and its analogs. IV. Absolute quantum yield of ion radical formation during photooxidation of chlorophyll a by n-benzoquinone]. The values of absolute quantum yield phi of the formation of free ion-radicals during the illumination of alkohol solutions of chlorophyll alpha (Chl) and rho-benzoquinone (Q) at room temperature were obtained by the method of impulse photoconductance. With an increase of the dielectric constant epsilon of the solvent from approximately 6 to approximately 25 phi increases by two orders ( approximately 10(-3)--approximately 10(-1). That obtained relationship phi (epsilon) is explained by epsilon effect on the efficiency of dissociation of "solvent-shared" ion-radical pair Chls+. Os-. The comparison of experimental data and theoretically expected ones allowed the estimation of some parameters to be obtained which characterize the ion-radical pair: interionic distance (10 A), the dissociation velocity constant ( approximately 10(5)--10(8) s-1), the velocity constant of reverse electron transfer (10(8) s-1), the life time approximately 10(-8) s).


[Intensification of the x-ray chemiluminescence of serum albumin solutions by the addition of dyes]. Effect of dyes of different classes on characteristics of X-chemoluminescence of human serum albumin solutions is studied. Intensification of lumininescence by the addition of uranin, eosin, tetrachlorfluorescein and erythrozan was found. The process of luminescence intensification with the addition of uranine was thoroughly studied (kinetic regularities, spectra, concentration relationships). It has been shown that kinetic regularities specify mainily the rapid component of X-chemoluminescence, that the initiation of chemoluminescence is related to the reactions of protein groups with hydroxyl radicals, that the intensification of luminescence proceeds in the protein-dye complex, that light emission of activated chemoluminescence took place from the singlet levels of the bound dye.


[Distribution of atomic density in protein globules]. The distribution of atomic density in the elastase and subtilysin globulas was modeled on the basis of their x-ray atomic coordinates and was consequently investigated through comparison with the normal Poisson distribution, using the chi2-test. The results from the above procedure are discussed in connection with the concept of kinetic constraints on the globula folding process as well as with the enzyme-machine hypothesis. It is shown that the minimum average dimensions of atomic irregularities in the protein globula are about 200 A3.


[Microcalorimetric study of thermodynamic values of aqueous phase transition and eutectic melting in the binary and ternary systems Na-DNA--H20 and Na-DNA--H20--NaCl]. Thermodynamic parameters of water phase transition and eutectics melting in DNA water-salt solution were studied by means of low temperature scanning differential microcalorimetry at different concentrations of polyanions. DNA hydration was measured and the character of changes in Na+ counterion binding was revealed during the transition of double helix into the state of random coils.


[Theoretical study of the effect of several reverse reaction on the kinetics of the primary processes of photosynthesis]. A theoretical model of energy migration and electron transport in photosynthesis of higher plants was considered. The set of different equations describing these processes takes into consideration the states of 4 components of electron transport chain and back reactions of electron transfer from the reduced acceptors to the oxidized reaction centres. The numerical integration of these equations was made for various kinetics parameters characterizing the electron transport chain.


[Role of nonspecific complex formation in protein-nucleic acid recognition]. Combinatory mathematical model of equilibrium binding of recognising proteins to DNA has been considered. The expression for the ratio of specific and unspecific complex as the function of a number of nucleotides in DNA, a number of centers of recognition, concentration of recognising molecules and a code number have been obtained. The analysis of obtained expression for the repressor--operator system showed that binary code would preferable than quartic one. The specificity of binding corresponding to experimental results have been observed by the number of centers more than twenty, in the narrow interval of the energy value and by high limitation on the number of combinations of error centers.


[Electrophoretic mobility of bimolecular lipid membranes]. The floating membrane vesicle is fixed by the counter solution flow in different points along the radius of a cylinder electrophoretic chamber, which permits to measure the vesicle electrophoretic mobility (EM). Close state condition of the chamber is provided for by the capillary system successively connected with the chamber. Relationship between EM of bimolecular lipid membranes (BLM) and pH and ionic concentration of aqueous solution qualitatively coincides with similar relationship for liposomes. The EM value of BLM essentially decreases in solution containing polyene antibiotics nystatine and levorin when derivative of cholesterol having 3betaOH-groups is present in the membrane.


[Concentration of black spots and the effect of detergents on black lipid membranes]. Effect of water-soluble detergents, such as triton X-100, saponin and trimethyl octadecylammonium bromide on the concentration of black spots, tension and stability of black lipid membranes was studied. Changes in mechanic stability of the lipid bilayer are discovered, which are in a good correlation with the litic effect of true detergents on cell membranes.


[Water molecule mobility in the surface layer of a membrane recorded with the fluorescent probe 4-dimethylaminochalcone]. A scheme of the location of a fluorescent probe 4-dimethylaminochalcone (DCM) in a phospholipid membrane has been proposed. According to the scheme the DMC dimethylamino group is located near phosphate groups and the oxygen atom--in the carbonyl groups region of phosphatidylcholine molecules. It is shown that DMC fluorescence is dynamically quenched by water molecules in the membrane. Therefore the quantum yield and, partly the position of DMC fluorescence maximum are determined by the water concentration near the probe, by the ability of water molecules to penetrate into the membrane as far as the carbonyl groups of fatty acid residues and by the water mobility in the membrane layer.


[Structural transformation of human erythrocyte membranes initiated by group specific antibodies]. Some changes have been found in the rates of the desintegration by sodium dodecylsulfate of human erythrocite membranes (EM) after incubation with specific group antibodies (GA) from incompatible blood. GA have no effect on the disintegration rates of EM by sodium desoxycholate and Triton X-100. The data are considered as the evidence of the structural transition in EM induced by GA and resulting in modification of integrative coupling forces primarily in the protein components of the membrane. The stopflow technique has been used to investigate the dependence of the desintegration rates in the quick phase (10 to 100 ms) upon the GA concentrations in the incubation medium and upon the incubation time. The obtained curves are distinctly S-shaped that is peculiar of cooperative processes.


[Dipole cooperative model of ion channels of excitable biomembranes. Conductance of ion channels]. An analysis of ionic channel conductance is presented in terms of dipole cooperative model. The dependence of conductance on displaced charge is found to be an S-shaped function. Basing on this function and kinetics of gating currents, the kinetic curves for the conductance are calculated. These curves are compared with Hodgkin--Huxley results on sodium channel. A good agreement may be observed for the case of positive jumps of the potential. Less accurate coincidence takes place for negative jumps of the potential.


[Propagation of impulses through the continuous heterogeneity of an excitable medium]. A simple method of analysing dynamic processes during pulse propagation is described. A change in duration of pulses and interpulse intervals in the course of propagation is taken into consideration. It is shown that due to inhomogeneity the excitation fronts are grouped into peculiar "cluster" moving at a low rate. It is also indicated that after passing the "cluster", the influence of inhomogeneity upon the form of the propagating consequence of pulses is essentially weakened.


[Mathematical model of neuronal adaptation taking into account the effect of calcium on membrane permeability to potassium ions]. A model of the adaptive neurone was suggested to base on the effect of increasing the potassium permeability during the increasing the intracellular calcium concentration. Calcium accumulation occurs due to entrance of calcium ions into the cell in the course of the potential action development. Extent of influence of the intracellular calcium on the potassium permeability and velocity of moving the calcium off the cell was obtained from Meech's results. Frankenhauzer--Huxley equation was used for computation of membrane excitation, however, in our case the subthreshold potassium inactivation was reduced. Thus, the adaptation phenomenon was simulated in the following succession: 1) calcium accumulation in the cell, 2) increasing the potassium permeability, 3) increasing the after hyperpolarization and 4) increasing the interspike intervals.


[Modeling the effect of rhythm on the strength of myocardial contraction]. A linear three-pool model of rhythm-inotropic phenomena in the cardiac muscle is proposed. Dynamics of accumulation and liberation of calcium from intracellular pools is described by differential equations. It has been shown by numerical experiments that rhythm-inotropic phenomena in the normal cardiac muscle and under cardiac insufficiency can be described qualitatively in terms of the concept on calcium recirculation in intracellular pools.


[Conditions for the development of auto-oscillations in the hematopoietic system]. Oscillations occur when the time of delay in the feed-back chain is increased or when the control system of hemopoiesis is "roughened". The analysis of clinical and experimental material indicates that initiation of oscillations seems not to be connected with cell interaction in the bone marrow; it is determined by the feed-back chain from the periphery to the hemopoietic organs. As the same time the role of intercellular interactions is essential for the transfer of autooscillations, initiated in some branches of hemopoiesis, to its other shoots. Oscillations in hemopoiesis with a period of three weeks or more recorded sometimes in humans are evidently initiated in the myeloid shoots, while the oscillations with the period of one and a half--two years--in the erythroid one.


[Model of local spectral description of images in the visual system]. On the basis of experimental evidence presented earlier a model of local spectral analysis of the image performed by the complex receptive fields of the visual cortex has been proposed. An essential feature of the model is that the generalized piece-wise Fourier transform is performed not over the image luminance function but over the logarithm contrast function resulted from analysis of the image by the round receptive fields of the preceding levels. Such an assumption removes a number of experimental objections offered against the hypothesis of two-dimensional Fourier transform in the visual system. The consequencies from the piece-wise expansion in a series of basic functions have been considered and among them: the channel frequency characteristics which can have more than one maximum; the possibility of describing the image by a limited number of channels with overlapping frequency characteristics.


[Assessment of the anisotropic stiffness component of the basilar membrane]. The average through the section components Dy and Dx of the basilar membrane anisotropic stiffness are evaluated from Bekesy's hydrostatic and hair probe experiments. A contradiction is found between the values and the behaviour of Dy component, calculated from the hydrostatic experiment and from the hair probe. The solution of the strongly bent plate equation for the average through the section transversal component of the basilar membrane anisotropic stiffness is obtained by the asymptotic method. A significant divergence between effective and bending stiffness can exist if the thickness of the human basilar membrane is about twice of that of the guinea pig.


[Determination of the direction and degree of an animal's tendency to migrate based on a theoretico-probabilistic analysis of its movements in a maza]. Using Markov chains a mathematical model of animal displacement in the final labyrinth is obtained. Direction and value of animal tendency towards migration from a given location point are reflected in the complex of absolute frequencies of the system appearing in its states. When estimating the tendency towards migration in the applied labyrith the whole complex of frequencies can be featured by its component, e. g. by the frequencies of animal appearance in the extreme labyrinth passages.


[Protonophoric and uncoupling activity of water-soluble pea flavonols]. In the experiments with artificial lipid membranes and mitochondria the watersoluble pea flavonols are demonstrated to possess weak protonophoric and uncoupling activities which correlate with each other. It is concluded that the mechanism of flavonol uncoupling activity is the same as for classical uncouplers. The results support the earlier suggestion that one of the flavonol functions in the plants may be the regulation of the energetics and metabolism.


[Ferricyanide ion binding sites on the surface of lecithin liposomes]. Interaction of ferricyanide ions with sonicated lecithin liposomes has been studied by (1)H-NMR. Ferricyanide induced shifts have been shown to change along the choline chain of the lecithin head group. The magnitude of the shift decreases as the distance from the positive end of zwitterionic moiety increases. It is concluded that ferricyanide ions bind to the positive charged ammonium groups of the phospholipid.


The effects of maternal phlebotomy and orally-administered erythropoietin (Ep) on erythropoiesis in the suckling rat. Erythropoiesis was stimulated in 2- to 5-day-old neonatal rats suckled by phlebotomized mothers. This was established by increases in: hemoglobin levels, mean corpuscular hemoglobin concentration and percentages of peripheral reticulocytes. The oral administration of cow milk containing 4 IU human erythropoietin (Ep) to 10-day-old normal neonates for 4 days induced a reticulocytosis. Significant amounts of Ep appeared in the plasma of 1-day-old rats nursed by mothers bled 3 days prior to delivery as compared to nondetectable levels in 1-day-old control rats of normal mothers. The data suggest that Ep is transmitted to neonatal rats via maternal milk, and escapes inactivation, at least to some extent, in the process of absorption from the gastrointestinal tract with consequent stimulation of erythropoiesis in these animals.


Effects of the teratogenic folic acid antagonist, 9-methyl pteroylglutamic acid on uronic acid levels in fetal rat limbs. Experimental pregnant rats were placed on a transitory folic acid-deficient regimen, i.e. dietary restriction of folic acid plus the teratogen and folic acid antagonist, 9-methyl pteroylglutamic acid; a regimen resulting in multiple congenital skeletal malformations. Controls received a folic acid-supplemented regimen. Accumulation of a primary component of the extracellular matrix, glycosaminoglycans (GAG), was quantitatively evaluated by measuring uronic acid concentrations in fetal limbs. On days 16 and 18 of gestation, fetal limbs were removed, pooled from each litter, and prepared for uronic acid, protein, and DNA quantitation. The treatment results in (1) a decreased rate of protein and DNA accumulation prior to day 16 of gestation, the rate not being affected from day 16 to day 18 of gestation; (2) a trend toward an increased rate of uronic acid accumulation prior to day 16 of gestation, and (3) a decreased rate of uronic acid accumulation from day 16 to day 18 of gestation. Furthermore, our observations confirm our earlier suggestion that there is a decreased rate of accumulation of some nonprotein component(s) in fetal limbs obtained from folic acid-deficient mothers from day 16 to day 18 of gestation.


Oxygen consumption of the fetal sheep in utero. Oxygen consumption was measured in 8 chronically instrumented fetal sheep by a combination of recently introduced techniques. Umbilical blood flow was measured by an electromagnetic flow transducer placed around the common portion of the umbilical artery. Blood representative of that in the umbilical artery was obtained from the distal aorta. The common portion of the umbilical vein was catheterized by direct puncture of the vessel at the base of the umbilicus. An accurate micromethod was used to measure oxygen content of blood from the umbilical vessels, and oxygen consumption was calculated by application of the Fick principle. The mean fetal oxygen consumption was 7.9 +/- 1.8 ml O2/min/kg fetus.


Fetal pepsinogens in human amniotic fluid. The presence of group I (Pg I) and group II (Pg II) pepsinogens was determined in 59 samples of human amniotic fluid between 11 and 40 weeks of gestation. Pg I was present in all of the samples, while Pg II was present only in samples of gestational age 32 weeks or older. No differential pattern of the fractions was present, although the first fraction of Pg I was not present in any of the samples. The sequential appearance of Pg I and Pg II suggests their fetal origin and that the synthesis of Pg I by fetal gastric mucosa may precede that of Pg II, thus serving as a potential marker of fetal maturity.


Ultrastructure of the cells in the peripheral blood of human embryos at early gestational stages. The presence of the different blood series in the peripheral blood of 10- to 18-week-old human embryos was followed by electron microscopy. It has been demonstrated that the earlier the stage of embryonic development, the more immature cells are found in the peripheral blood. This phenomenon may suggest migration of blood cell progenitors from earlier to more definitive sites of embryonic erythropoiesis.


Postnatal development of rats born preterm and postterm. I. Body weight. Litters with 3 preterm, 3 term and 3 postterm littermates have been fed by one mother each. Fetal body weight continues to increase in utero if the normal gestational period is extended by 1 day. But this intrauterine weight gain is smaller than the postnatal weight gains of term rats of the same conceptional ages. While the body weights of term and postterm rats increase rapidly immediately after birth, there is a lag phase of 3 days in preterm animals. This delay in weight gain is not caught up during a period of 30 postnatal days. This appears to be due to malnutrition in the early postnatal period. After the 20th day of life, the weight gain markedly increases in all groups, indicating the effect of supplemental feeding in the weaning period.


Particulate and free hexokinase in fetal rat liver. The association of hexokinase with particulate fractions of liver has been studied during the development of the rat. In the fetal rat liver about 50% of the total hexokinase is bound to the mitochondria. This proportion decreases gradually after birth. No association of hexokinase with mitochondria could be demonstrated in the adult rat liver. It is suggested that the binding of hexokinase to the mitochondria is a consequence of a property which is lost during development of the mitochondrial membranes. At least part of the hexokinase is rather tightly bound to the mitochondria. Glucose-6-phosphate or ATP do not solubilize the enzyme. The proportion of hexokinase bound to the mitochondria is independent of the metabolic state of the hepatocyte as exemplified by studies with inhibitors of oxidative phosphorylation, using the digitonin technique for the separation of particulate and cytosol fractions of isolated fetal rat hepatocytes.