Identification of tumour rejection antigens recognized by T lymphocytes. On the basis of the results reviewed here, there are two major mechanisms whereby tumour rejection antigens may arise. The first mechanism is mutational. Point mutations occurring in a large variety of genes may produce new antigenic peptides, either by providing them with the ability to bind to MHC class I molecules or by providing them with a new epitope (Fig. 2). The second mechanism is the activation of a gene that is silent in normal tissues and for which no strong natural tolerance has been established. Plausible candidates for the mutational mechanism are the "tumour specific transplantation antigens" observed on methylcholanthrene induced tumours and tumours induced by ultraviolet light. The diversity of these antigens appears to be very large, like that of the tum- antigens. Moreover, these tumours have been obtained with high doses of carcinogens, which are proven mutagens. On the other hand, a P815 tumour rejection antigen appears to arise through the activation of a silent gene, and it may turn out that this is the rule for most tumour rejection antigens. It is our hope that other genes coding for mouse and human tumour rejection antigens will soon be identified, so that it will become clear whether the activational mechanism is the rule or the exception. In our view, this is a crucial issue. Insofar as tumour rejection antigens result from mutations, they may be highly specific for every individual tumour. The tumour specific nature of these antigens would then be easily ascertained. However, active immunization of cancer patients would require that a tumour cell line be obtained from each patient, a most unpractical prospect. If, on the other hand, production of tumour rejection antigens results from the activation of a normal gene, then there is a good probability that the same gene may be activated in many different tumours, being perhaps preferentially shared by tumours of the same histological type. This would probably not result in the expression of the same antigen in all these tumours, because the patients would differ in their presenting molecules, which are determined by their HLA haplotype. However, a subset of the tumours expressing the same "tumour rejection" gene should share the same class I restricting element, so that all of these patients could be immunized with a cell that would express the gene and carry the appropriate HLA molecule.(ABSTRACT TRUNCATED AT 400 WORDS)


T cell responses to human malignant tumours. The immunological and molecular mechanisms that govern T cell responses to human malignant tumours are just starting to be understood within a more complex framework of humoral, cellular and molecular interactions. The definition of multiple antigens simultaneously expressed on human melanoma, as detected with cytolytic T cells in immunoselection experiments, is a first step towards the molecular characterization of these antigens. Observations on the influence of expression of restriction elements of the major histocompatibility complex on the recognition of these tumour associated antigens have advanced our understanding of how the immune system responds to cancer cells in vivo. It is specificity that is tuning the immune system, not only in cancer. The molecular characterization of the first human cancer antigen recognized by CTL is now under way as outlined by Boon et al in this issue.


Lessons from T cell responses to virus induced tumours for cancer eradication in general. Immunotherapy of virus induced tumours by adoptive transfer of virus specific cytotoxic T cells (CTL) is now feasible in experimental murine systems. These CTL recognize viral peptide sequences of defined length presented in the groove of MHC class I molecules. Effective eradication of large tumour masses requires coadministration of IL-2. In essence, T cell immunity against virus induced tumours does not differ from anti-viral T cell immunity in general. Tumour escape strategies are numerous but, in various instances, can be counteracted by defined measures. Initiation of CTL responses against poorly immunogenic non-virus induced tumours (the majority of human cancer) requires novel strategies to overcome T cell inertia. Rather than waiting to see whether tumour specific CTL (against unknown antigens) can be cultured from TIL, we propose an alternative strategy in which CTL are raised against target molecules of choice, including differentiation antigens of restricted tissue distribution (autoantigens) or mutated/overexpressed oncogene products. The various steps proposed include: (a) identification of target molecules of choice; (b) identification in these target molecules of MHC allele specific peptide motifs involved in peptide binding to MHC molecules; (c) evaluation of actual binding of such peptides to specific MHC class I molecules; (d) in vitro CTL response induction by such peptides, presented either by highly efficient antigen presenting cells (such as processing defective cells, which carry empty MHC class I molecules) loaded with a single peptide or by dendritic cells, both cell types being capable of primary CTL response induction in vitro and (e) adoptive transfer of tumour specific CTL generated in vivo or, more conveniently, vaccination with immunodominant peptides. The latter possibility seems to be feasible because peptide vaccination with a single immunodominant viral peptide can install CTL memory and confer protection against lethal virus infection.


The importance of steroid hormones in prostate cancer. Steroid hormones have an important role in prostate biology. Androgens are crucial for the normal development of the prostate gland and in maintaining its functional state in the adult. It seems that the prolonged presence of androgens might also be an important factor in the development of prostate cancer. In addition, androgens and oestrogens appear to play some part in the development of benign prostatic hyperplasia, although the exact nature of their role has not been clearly defined. Stimulation of prostate cancer growth by androgens is well established, with androgen withdrawal therapy constituting the most effective therapy in men with prostate cancer. Additive steroid therapy of metastatic prostate cancer with oestrogens or progestins has also proven effective. The effects of androgens on prostate cancer cell growth might be mediated through modulation of growth factor expression and alteration of growth factor receptor levels. Androgen response can be modulated by the expression of mutated oncogenes such as ras. Androgen independence can occur through a loss of AR expression or mutation of the AR; however, the patterns of AR expression in normal prostatic tissue from development to adulthood and in cancer are now just beginning to be described. Other steroids, such as the retinoids, show promise as preventive agents, possibly through the modulation of growth factors.


The importance of normal and abnormal oestrogen receptor in breast cancer. We have used the screening techniques of CMC and SSCP of selected PCR fragments, and also gel retardation assays, to discover a number of ER variants in clinical breast cancer tissues. We have found base pair insertions, transitions, and deletions, and deletions of exons 3, 5 and 7. Using a yeast transactivation assay, we have discovered receptors with outlaw function consisting of both dominant positive receptors that were transcriptionally active in the absence of oestrogen and dominant negative receptors that were transcriptionally inactive themselves but prevented normal ER function. Future efforts should focus in particular on such dominant positive and dominant negative variants. With regard to positive variants, we should like to know whether they stimulate tumour growth and, if so, whether they can be turned off. With regard to dominant negative variants, we should like to determine whether they can inhibit tumour growth and, if so, whether they can be turned on.


Cellular heterogeneity and mutant oestrogen receptors in hormone resistant breast cancer. In summary, we propose that the molecular heterogeneity of ER in breast tumour cells, characterized by the presence of mutant receptor forms, generates the cellular heterogeneity evident when PR or DNA ploidy are analysed in cell subpopulations. Furthermore, it is likely that cellular heterogeneity leads to the lack of uniformity in response to tamoxifen that we have described. We find that heterogeneity of PR and DNA ploidy reflects the existence of mixed subpopulations of breast cancer cells that are substantially remodelled under the influence of tamoxifen. It appears likely that different subsets of cells, rather than being "resistant", can be inhibited or stimulated by tamoxifen and that their suppression or outgrowth alters the phenotype of the tumour. PR heterogeneity in solid tumours of patients may predict a mixed, and potentially dangerous, response to anti-oestrogen treatment. As we learn more about the heterogeneity of PR, ER and other proteins in tumours, we may be able to recognize such lethal subpopulations, which the flow cytometry immunoassay can simply and rapidly measure. Our data also suggest that the use of tamoxifen as a chemopreventant in women at high risk of developing breast cancer (Kiang, 1991) should be viewed with caution.


Immunolocalization of steroid hormone receptors in normal and tumour cells: mechanisms of their cellular traffic. Experimental conditions are described for the detection of steroid receptors in tissue sections or cells at the light microscope level. Current knowledge about the ultrastructural distribution of these receptors is summarized; the mechanisms of their nuclear localization are described. Karyophilic signals involved in nuclear translocation are characterized by means of in vitro mutagenesis of steroid receptor cDNAs. Studies analysing the subcellular distribution of various transfected receptor mutants in energy depleted cells together with fusion experiments provide evidence for nucleoplasmic shuttling of progesterone receptors. We conclude that the "nuclear" location of the wild type progesterone receptor reflects a dynamic equilibrium between active nuclear import and outward diffusion. We also describe the use of immunocytochemistry in pathology, especially for the detection of steroid receptors in hormone dependent tumours.


A molecular strategy to control tamoxifen resistant breast cancer. Our research goal is to develop possible strategies that could have therapeutic implications for the control of breast cancer. Although tamoxifen therapy is successful for some patients, it does not provide adequate benefit for the majority, who have ER negative disease. There is also both laboratory and clinical evidence to support the position that initially responsive tumours will eventually develop resistance to tamoxifen therapy. Since the ER mechanism is the key to the successful control of tumour growth with anti-oestrogens, we have taken the strategic step of determining whether the ER will reassert growth control in breast tumour cells. We have demonstrated that this is feasible, and it might now be appropriate to plan a "gene therapy" approach to cancer control that is based on reactivation of the ER or the development of a targeted vector. Since the concept of growth control in refractory breast cancer has become a reality, there can now be enthusiasm about developing a means to achieve this therapeutic goal. Indeed, the implications for cancer therapy could be enormous. There is every reason to suppose that other types of cancer cells transfected with steroid receptor genes will respond with growth suppression to the appropriate ligand. We have further broadened our studies of anti-oestrogens to describe a laboratory model to dissect the molecular pharmacology of hormone and anti-hormone action. In practical terms, the model has provided an insight into tamoxifen stimulated growth as a mechanism of tamoxifen resistance. The pharmacology of a model compound, fixed ring 4-hydroxytamoxifen, was changed by a mutant ER. It is possible to envisage the clonal selection of cells with mutated ER or ERE that will thrive on the partial agonist actions of tamoxifen. These cells would, as is observed in the MCF-7 TAM and EnCa101 laboratory models, also respond to oestradiol stimulation. Future studies of mutant receptors in the laboratory and clinic might provide support for a novel mechanism of tamoxifen resistance. What is most encouraging, though, is the finding that the pharmacology of new pure anti-oestrogens is not affected by the mutation in the ER and that the pure anti-oestrogens can control tamoxifen stimulated growth. These observations provide additional support for the development of pure anti-oestrogens as a therapy for breast cancer. A clinically acceptable compound could be used as a therapy after tamoxifen failure or perhaps the compound may prevent the development of receptor mutants if it is used as a first line therapy.


Steroid antagonists as nuclear receptor blockers. Molecular analysis of sex steroid receptors, together with the availability of a range of ligands for these receptors that affect differentially the physiological actions of the ligand-receptor complex in the cell nucleus, is providing new insights into the processes that control transcriptional activation leading to cell growth. These studies serve to focus attention on the importance of other cell specific factors that are important in determining the transcriptional efficiency of the hormone-receptor complex. Elucidation of the nature and role of such factors may lead ultimately to hormonal or anti-hormonal agents targeted to modulate selected hormone mediated events in specific cells or organs. The sex steroid receptors are prototypes of a much larger family of proteins that control transcription, including proteins that bind to ligands known to be important physiologically, such as thyroid hormones and retinoids, as well as "orphan" receptors for which no ligands have been described. The established value of steroid antagonists in cancer therapy suggests that further developments in the understanding of new members of the steroid receptor superfamily may lead to the development of novel anti-cancer agents. The developing understanding of "cross talk" between steroid-receptor and growth factor-receptor mediated tumour growth stimulatory pathways may also provide previously unrecognized opportunities for tumour therapy.


Androgen receptor mutants that affect normal growth and development. The elucidation of the molecular structure of the human androgen receptor has facilitated the study of molecular defects associated with androgen insensitivity. In this overview, data are presented on the functional domain structure of the wild type human androgen receptor and on the molecular structure of the androgen receptor from different subjects with the complete form of androgen insensitivity. Mutational domain analysis of the human androgen receptor has revealed that a large carboxyterminal region constitutes the hormone binding domain and that DNA binding is associated with a central basic domain. In addition, separate domains that control trans-activation and nuclear translocation have been identified. Reports on androgen receptor gene structure in individuals with the complete and incomplete forms of androgen insensitivity indicate that gross deletions within the androgen receptor gene are uncommon. The locations of the different point mutations reported cannot be assigned to a single site but are spread throughout the ligand binding and DNA binding domains. A point mutation found in the ligand binding domain of the human androgen receptor in a prostate tumour cell line is the cause of the altered steroid binding specificity observed for the androgen receptor in these prostate tumour cells. A considerable variation in the length of one of the polyglutamine repeats has been reported in the aminoterminal transcription regulating domain of the wild type androgen receptor. Doubling of the length of this particular polyglutamine stretch is correlated with a progressive spinal/bulbar muscular atrophy in a small group of middle aged men.


Clinical, immunopathologic, and therapeutic considerations of inflammatory myopathies. The inflammatory myopathies encompass a group of heterogenous muscle diseases which have in common an acquired myopathy with histological signs of endomysial inflammation. We present evidence based on recently emerged clinical, histologic, immunopathologic, demographic and therapeutic observations that these myopathies comprise three major and distinct groups: polymyositis (PM), dermatomyositis (DM), and inclusion-body myositis (IBM). Immune-mediated mechanisms characteristic for each group appear to play a primary role in the pathogenesis of these diseases. In DM there is an intramuscular microangiopathy mediated by the C5b-9 membranolytic attack complex, leading sequentially to loss of capillaries, muscle ischemia, muscle fiber necrosis and perifascicular atrophy. In contrast, in PM and IBM the muscle fiber injury is initiated by sensitized CD8+ cytotoxic T cells that recognize MHC-I restricted muscle antigens, leading to phagocytosis and fiber necrosis. Among the viruses implicated in the cause of inflammatory myopathies, only the retroviruses, HIV, HTLV-1 and simian retroviruses, have been convincingly associated with PM. Retroviruses, therefore, appear to be the leading group of viruses capable of triggering these diseases. The treatment of inflammatory myopathies has been largely empirical. A detailed therapeutic plan based on our experience with a large number of patients is presented. Patients with bona fide PM or DM respond to steroids to some degree and for some period of time. In contrast, patients with IBM do not respond to any therapy and the disease should be suspected when a patient with presumed PM has failed treatment. Methotrexate and cyclophosphamide are disappointing. Cyclosporine and Azathioprine are commonly used but they are of uncertain benefit. Plasmapheresis is ineffective. High-dose intravenous immunoglobulin is a promising new therapeutic modality.


Pharmacodynamics of the hypotensive effect of levodopa in parkinsonian patients. Blood pressure effects of i.v. levodopa were examined in parkinsonian patients with stable and fluctuating responses to levodopa. The magnitude of the hypotensive effect of levodopa was concentration dependent and was fit to an Emax model in fluctuating responders. Stable responders demonstrated a small hypotensive response. Baseline blood pressures were higher in fluctuating patients; a higher baseline blood pressure correlated with greater hypotensive effects. Antiparkinsonian effects of levodopa temporally correlated with blood pressure changes. Phenylalanine, a large neutral amino acid (LNAA) competing with levodopa for transport across the blood-brain barrier, reduced the hypotensive and antiparkinsonian effects of levodopa. We conclude that levodopa has a central hypotensive action that parallels the motor effects in fluctuating patients. The hypotensive effect appears to be related to the higher baseline blood pressure we observed in fluctuating patients relative to stable patients.


Elevated plasma immunoreactive beta-endorphin in anorexia nervosa. Basal morning plasma levels of immunoreactive-beta-endorphin (ir-beta-EP), and 17-beta estradiol (E2) were assessed in 25 adolescents with anorexia nervosa (AN) in comparison to 24 healthy controls. All subjects were drug free for at least 6 weeks. The mean plasma level of ir-beta-EP was significantly higher (84%) in the AN patients when compared with the control subjects. The elevated plasma ir-beta-EP may be relevant to the suppression of appetite, tolerance of fasting, and to the hypothalamic hypogonadism in AN.


Acetazolamide improves action myoclonus in Ramsay Hunt syndrome. The myoclonus of two patients with Ramsay Hunt syndrome was only partially controlled under treatment with clonazepam, sodium valproate, primidone, and piracetam. Acetazolamide (200 mg daily) was added to these drugs, resulting in a dramatic improvement. Placebo substitution (one patient) and withdrawal of acetazolamide in the other patient resulted in marked aggravation of the myoclonus. The mechanism of action of acetazolamide in myoclonus is unknown. Acetazolamide may be an additional therapeutic possibility for patients with severe action myoclonus.


Amnestic syndrome associated with propranolol toxicity: a case report. An elderly woman developed an Alzheimer-like subacute dementia as a result of propranolol toxicity. Analysis of the manifestations showed that severe impairment of memory accounted for virtually all of the abnormalities. There is evidence that cerebral reactions to drug toxicity can exhibit patterns that suggest highly selective involvement of functional subdivisions of the brain.


Naloxone or haloperidol but not yohimbine reverse apomorphine-induced respiratory depression. Intravenous injection of low doses of naloxone was found to reverse the respiratory depression induced by apomorphine in chloralose-anesthesized dogs. Similar results were obtained with haloperidol, whereas yohimbine remained ineffective. These data suggest that apomorphine depresses respiratory rate through a mechanism involving both dopamine and opiate mechanisms but not alpha 2-adrenoceptors. Respiratory arrest induced by overdosages of apomorphine can be treated with naloxone.


Conformational analysis of levanbiose by molecular mechanics. A relaxed conformational energy map for levanbiose, O-beta-D-fructofuranosyl-(2----6)-beta-D-fructofuranoside, was computed with the molecular mechanics program MM2(87). All torsion angles of the three linkage bonds were driven by 30 degrees increments while two primary alcohol groups were held at three staggered forms. The steric energy of all other parameters was optimized. The side groups were retained at the same relative positions on the two rings in this first part of the study so our results are directly applicable to the study of polymeric levan with identical repeating units. The low-energy dimers did not lead to viable polymers. The interresidue linkage torsion angles defined by C-6-O-2'-C-2'-C-1' (phi) and O-5-C-5-C-6-O-2' (omega) have minima at +60 degrees and -60 degrees, respectively, with accessible minima at other staggered forms. As observed in inulobiose, the preferred torsion angle at central linkage bond defined by C-5-C-6-O-2'-C-2' (psi) was antiperiplanar. An analysis of all conformations of staggered side groups showed that the C-1 and C-1' groups had little effect but the C-6' group showed a preference for chi-6'(O-5'-C-5'-C-6'-O-6') = -60 degrees. The fructofuranose rings were started at the low-energy 4(3)T conformation (angle of pseudorotation, phi 2 = 265 degrees) that was retained except when the linkage conformations created severe inter-residue conflict.


Synthesis of a phenyl beta-avobioside derivative of the disaccharide component of avoparcins. The synthesis of the phenyl beta-glycoside of avobiose, a disaccharide fragment present in the antibiotic avoparcin, is reported. It is based on glycosylation of phenyl 3,4,6-tri-O-benzyl-beta-D-glucopyranoside with 2,3,6-trideoxy-4-O-p-nitrobenzoyl-3-trifluoroacetamido-L-ribo-hex- 1-enitol, a fully protected glycal of L-ristosamine, in the presence of trimethylsilyl triflate.


The reaction of some dicarbonyl sugars with aminoguanidine. The reactions of aminoguanidine (guanylhydrazine) with 3-deoxy-D-erythro-hexos-2-ulose (1a), 3-deoxy-D-glycero-pentose-2-ulose (1b), D-erythro-hexos-2-ulose (1c), and D-glycero-pentose-2-ulose (1d) were examined at 37 degrees at a solution pH of 7.0 (phosphate buffer). For 1a and 1b, two major products were observed and shown respectively to be the 5- and 6-substituted 3-amino-1,2,4-triazine derivatives. The ratios of the products were independent of the amount of aminoguanidine present or the order of mixing the reagents prior to the experiments. For 1c and 1d, only the 5-substituted triazine derivatives were formed. No evidence for hydrazone or bishydrazone formation was observed.


Immunochemical characterization of polyclonal and monoclonal Streptococcus group A antibodies by chemically defined glycoconjugates and synthetic oligosaccharides. Synthetic oligosaccharides of increasing complexity that represent different epitopes of the Streptococcus Group A cell-wall polysaccharide were used as haptens and glycoconjugates of bovine serum albumin (BSA) and horse hemoglobin (HHb) to characterize polyclonal and monoclonal antibodies. Rabbits were immunized with the BSA glycoconjugates of a linear trisaccharide, branched trisaccharide, and branched pentasaccharide. The binding specificities of the polyclonal antisera were determined by a series of inhibition ELISA studies in which disaccharide through pentasaccharide haptens were used as inhibitors of antibody-glycoconjugate binding. Monoclonal antibodies derived from mice immunized with a killed bacterial vaccine were selected for their binding to native polysaccharide antigen coupled to BSA and the BSA glycoconjugates of the di- and linear tri-saccharides. Polyclonal antibodies were moderately specific for the oligosaccharide epitope of the immunizing glycoconjugate and only those antibodies raised to the branched pentasaccharide antigen showed cross-reaction with the bacterial antigen. The behaviour of selected monoclonal antibodies parallels the binding profile of polyclonal antibodies in that the two highest-titre antibodies were directed toward an epitope displayed by the branched pentasaccharide.


Formation of oligosaccharides from lactitol by Aspergillus oryzae beta-D-galactosidase. Six oligosaccharides were first formed from lactitol by a transgalactosylation reaction catalyzed by Aspergillus oryzae beta-D-galactosidase. From the results of methylation analysis, MS, and 1H- and 13C-NMR studies, it was concluded that these oligosaccharides are O-beta-D-galactopyranosyl-(1----4)-O-beta-D-galactopyranosyl-(1----4)-D- glucitol, O-beta-D-galactopyranosyl-(1----3)-O-beta-D-galactopyranosyl-(1----4)-D- glucitol, O-beta-D-galactopyranosyl-(1----4)-[O-beta-D-galactopyranosyl-(1----6)]- D- glucitol, O-beta-D-galactopyranosyl-(1----6)-O-beta-D-galactopyranosyl-(1---4)- glucitol, O-beta-D-galactopyranosyl-(1----4)-[O-beta-D-galactopyranosyl- (1----5)]-D-glucitol, and O-beta-D-galactopyranosyl-(1----4)-[O-beta-D-galactopyranosyl-(1----1)]- D-glucitol. The last three are newly observed oligosaccharides.


Rearrangement of unsaturated 2,4-O-benzylidenehexitol derivatives into C-glycosylbenzene derivatives. Acetolysis of (Z)-1,3-di-O-acetyl-2,4-O-benzylidene-6-C-(2,4-dichlorophenyl)-D-xylo-he x- 5-enitol (3) afforded (E)-1,2,3,4-tetra-O-acetyl-6-C-(2,4-dichlorophenyl)-D-xylo-hex-5-enit ol and 2-C-[(R)-acetoxy(2,4-dichlorophenyl)methyl]-3,4,6-tri-O-acetyl-2-deoxy- beta-L-galacto- and -beta-L-gulo-hexopyranosylbenzene. The mechanism of this new rearrangement was studied by exchanging the substituents at C-1 and C-3 in 3 and those of the aromatic ring attached to C-6.


The synthesis and characterisation of 2-O-(6-O-L-glycero-alpha,beta-D-manno-heptopyranosyl-alpha-D-glucopyran osyl)-alpha,beta-D-glucopyranose. The title compounds were synthesised, and appropriate derivatives were characterised by GLC, GLC-MS, and NMR spectroscopy. The GLC and GLC-MS data proved 2-O-(6-O-L-glycero-alpha-D-manno-heptopyranosyl-alpha-D-glucopyranosyl)- D- glucopyranose to be a constituent of the outer-core region of the lipopolysaccharide from Escherichia coli K-12, indicating the heptosyl residue to be linked to the terminal glucopyranose residue.


Glucosylenamines as glycosyl acceptors: synthesis of gentiobiosylenamines. The preparation of 2,3,4-tri-O-benzyl- (3), 2,3,4-tri-O-acetyl- (4), and 2,3,4-tri-O-benzoyl-N-(2,2-diethoxycarbonylvinyl)-6-O-trityl-beta- D-glucopyranosylamine (5) is described. The reaction of 3-5 with 2,3,4,6-tetra-O-acetyl-alpha-D-glucopyranosyl bromide yields 2,3,4-tri-O-benzyl- (9), 2,3,4-tri-O-acetyl- (10), and 2,3,4-tri-O-benzoyl-N-(2,2-diethoxycarbonylvinyl)-6-O-(2,3,4,6-tet ra-O- acetyl-beta-D-glucopyranosyl)-beta-D-glucopyranosylamine (11), respectively. 2,3,4-Tri-O-benzyl- (6), 2,3,4-tri-O-acetyl- (7), and 2,3,4-tri-O- benzoyl-N-(2,2-diethoxycarbonylvinyl)-beta-D-glucopyranosylamine (8) are also described.


Synthesis of the antibiotic cortalcerone from D-glucose using pyranose 2-oxidase and a novel fungal enzyme, aldos-2-ulose dehydratase. Using two enzymes purified from the white-rot fungus, Polyporus obtusus, 5% solutions of D-glucose have been quantitatively converted in vitro into D-arabino-hexos-2-ulose (D-glucosone) and subsequently into a compound having antimicrobial activity. The antibiotic has been shown by nuclear magnetic resonance and mass spectroscopy to be chemically identical to a previously described fungal metabolite known as cortalcerone. Based on kinetic analysis of the synthetic process, a pathway for the biosynthesis of cortalcerone is proposed, involving both chemical rearrangement and enzymically catalyzed steps. Two enzymes, pyranose 2-oxidase and a previously uncharacterized D-arabino-hexos-2-ulose-utilizing enzyme, may be sufficient for the biosynthesis of cortalcerone from glucose in vivo. The D-arabino-hexos-2-ulose-utilizing enzyme dehydrates certain aldosuloses and has been named aldos-2-ulose dehydratase. The enzyme, which appears to be a dimer of 95-kDa subunits, has been purified 450-fold. Additional properties of aldos-2-ulose dehydratase are described, including its apparent ability to catalyze two different steps in the proposed biosynthetic pathway for cortalcerone.


Studies of the interaction of the maltose-binding protein of Escherichia coli, a closed-groove binder, with 4,6-O-ethylidenemalto-oligosaccharides (dp 2-5) and its regioselective labelling with 3-azibutyl 1-thio-alpha-(6-3H)maltoside. Four malto-oligosaccharides (dp 2-5), each with a 4,6-O-ethylidene group on the glucosyl unit at the non-reducing terminus, were synthesised and used to prove that the maltose-binding protein (MBP) of E. coli is a closed-groove binder. alpha-D-Glucosylation of 3-azibutyl 1-thio-alpha-D-(6-3H)glucopyranoside yielded a 3H-labelled, photolabile 1-thiomaltoside derivative that was used to chemically modify the binding site of MBP. The 3H-labelled peptide containing 83% of the total radioactivity, which was isolated after tryptic cleavage of the modified MBP and sequenced, is part of the closed end of the MBP groove.


Synthesis of 4'-deoxy-4'-fluorokanamycin A and B. 4'-Deoxy-4'-fluorokanamycins A (17) and B (25) have been prepared through fluorinative ring-opening of the D-galacto-3',4'-oxiranes (8 and 21) derived from kanamycin A and B with potassium hydrogenfluoride in ethane-1,2-diol. The mechanism of preponderant formation of the 4'-deoxy-4'-fluoro-D-gluco (9 and 22) over the 3'-deoxy-3'-fluoro-D-gulo derivatives was discussed. In the synthesis of 25, the unusual 3',6'-epimine (23) was the main product along with the 4'-deoxy-4'-fluoro derivative. The mechanism of this reaction is also discussed. Both 17 and 25 were active against resistant bacteria producing aminoglycoside-adenylylating enzymes for HO-4'.


Crystal structure of lactitol (4-O-beta-D-galactopyranosyl-D-glucitol) trihydrate. Lactitol trihydrate, C12H24O11.3H2O, crystallises in the orthorhombic space group, P2(1)2(1)2(1) with cell dimensions a = 8.306(2), b = 10.163(1), c = 21.321(1) A, and V = 1799.8(5) A3; Z = 4, Dx = 1.47 Mg m-3, lambda(Cu-K alpha) = 1.54178 A, mu = 1.14 mm-1, F(000) = 856, and T = 23 degrees. There are one intra- and thirteen inter-molecular hydrogen bonds in the structure. The bond lengths and angles agree well with the mean values of related structures. The galactopyranosyl ring has a chair conformation.


The crystal structure and physicochemical properties of L-ascorbic acid 2-glucoside. The stable L-ascorbic acid glucoside produced by the action of the cyclomaltodextrin glucanotransferase (CGTase, EC 2.4.1.19) from Bacillus stearothermophilus was crystallized from an aqueous solution. Determination of the molecular structure by single crystal X-ray analysis showed the compound to be 2-O-alpha-D-glucopyranosyl-L-ascorbic acid (AA-2G). The crystals are orthorhombic, space group P2(1)2(1)2(1), with unit-cell dimensions a = 11.929 A, b = 24.351 A, and c = 4.864 A. The D-glucopyranose residue has the 4C1 conformation. These conclusions are in good agreement with those based on the 13C-NMR spectrum. The general physicochemical properties of crystalline AA-2G are reported.


Studies of the molecular recognition of synthetic methyl beta-lactoside analogues by Ricinus communis agglutinin. The 2-, 3-, 6-, 2'-, 3'-, 4'-, and 6'-deoxy derivatives and the 3-O-methyl derivative of methyl beta-lactoside have been synthesised and their binding to the galactose-specific agglutinin from Ricinus communis (RCA-120) has been investigated. The results indicate that HO-3,4,6 of the beta-D-galactopyranose moiety are the key polar groups. The main difference from the closely related ricin lectin RCA-60 involves HO-6 of the D-glucopyranose moiety, which seems to contribute to the binding of the carbohydrate to RCA-60 but not to RCA-120.


Investigation of the active site of Escherichia coli beta-D-galactosidase by photoaffinity labelling. 3,7-Anhydro-2-azi-1,2-dideoxy-D-glycero-L-manno-(8-3H)octitol++ + (1a) and 3-azibutyl 1-thio-beta-D-(6-3H)galactopyranoside (2a) were synthesised from the unlabelled compounds by reaction with galactose oxidase, then reduction with sodium borotritide. Whereas 1a was an efficient photoaffinity reagent for the beta-D-galactosidase from E. coli, 2a was ineffective. Three 3H-labelled peptides were isolated after digestion of the labelled enzyme with trypsin, one of which was an octapeptide (Trp 158 to Ser 165), which is remote from the segments detected as part of the active site of the enzyme.


Redox glycosidation: the use of Nozaki-Takai methylenylation in a highly stereoselective synthesis of sucrose. Sequential reaction of 2,3,4,6-tetra-O-benzyl-D-glucopyranose (7) with butyllithium and 2-[2,3,5-tri-O-benzyl-4-O-(tert-butyldiphenylsilyl)-D- arabinonoyl]thio-3-nitropyridine (6) at -78 degrees gave 2,3,4,6-tetra-O-benzyl-alpha-D-glucopyranosyl 2,3,5-tri-O-benzyl-4-O-(tert-butyldiphenylsilyl)-D-arabinonate+ ++ (8; 71%, alpha:beta greater than 50:1). Ester carbonyl methylenylation, desilylation, and iodoetherification in the presence of silica gave 3,4,6-tri-O-benzyl-1-deoxy-1-iodo-(2,3,4,6-tetra-O-benzyl-alpha-D- glucopyranosyl)-beta-D-fructofuranoside (15; 44%, alpha:beta greater than 50:1). This neopentylic iodide 15 was converted into sucrose (1;80%) by free-radical substitution using TEMPO (24) followed by sodium-ammonia reduction, acetylation, and Zemplén methanolysis.


Synthesis of 5-deoxy-5-fluoro and 5-deoxy-5,5-difluoro derivatives of kanamycin B and its analogs. Study on structure-toxicity relationships. 5-Deoxy-5-fluoro- (1), 5.3'-dideoxy-5-fluoro- (2), and 5,3',4'-trideoxy-5-fluoro-kanamycin B (3) have been prepared by treatment of 5-epihydroxyl precursors (prepared by the Mitsunobu reaction) with DAST as the key step. 5,3'-Dideoxy-5,5-difluoro- (26) and 5,3',4'-trideoxy-5,5-difluoro-kanamycin B (27) were also prepared by treatment of the corresponding 5-oxo derivatives with DAST. These 5-deoxy-5-fluoro and 5-deoxy-5,5-difluoro derivatives showed markedly decreased toxicity as compared with the parent compounds.


Apple-fruit xyloglucans: a comparative study of enzyme digests of whole cell walls and of alkali-extracted xyloglucans. Apple cell walls or alkali-extracted xyloglucans were digested with an endo-glucanase from Trichoderma viride and the resulting oligosaccharides were isolated by chromatography on Bio-Gel P-4. Three main oligosaccharides were present in similar proportions, and their structures were shown to be [Xyl(Glc)]3-Glc, [Xyl(Glc)]2-(FucGalXyl)Glc-Glc, and XylGlc-(GalXyP)Glc-(FucGalXyl)Glc-Glc. Each non-reducing-end Glc was 6-linked, each reducing-end Glc was 4-substituted, and each other Glc was 4,6-disubstituted. The Xyl was either terminal or 2-substituted, the Fuc was terminal, and the Gal was either terminal or 2-substituted. The 1H-NMR spectra of the oligosaccharides extracted directly from the cell wall showed that they are not acetylated. Other oligosaccharides, notably GalXyl3Glc4, Xyl2Glc4, and Xyl2Glc3, were present in smaller proportions in the digest of the cell walls.


[Better efficacy of K-strophanthidin versus digoxin in subjects with dilated cardiomyopathy and chronic heart insufficiency]. We evaluated the efficacy of K-strophanthidin and digoxin in 20 patients with stable, severe congestive heart failure. In this aim, we studied the left ventricular pump function at rest and following manipulation of the cardiac load (cold pressor test and nitroprusside infusion), the exercise performance (cardiopulmonary exercise test), and the level of circulating norepinephrine. The study was double-blind and cross-over and comprehended 4 periods of 1-week each during which patients received in random order: placebo (oral+intravenous), K-strophanthidin (intravenous + oral placebo), digoxin (oral+intravenous placebo and, in 8 patients, intravenous + oral placebo). The efficacy of the various compounds was tested at the end of each period 1 and 10 hours after drug dosing. Comparable results were obtained by the 2 sets of measurements. Both digoxin and K-strophanthidin showed a positive inotropic effect. This is shown by an upward shift of the ejection fraction/end-systolic stress. In spite of this, only K-strophanthidin significantly increased exercise performance: tolerance time (+153 s), peak oxygen consumption (+1.2 ml/kg/min) and oxygen consumption at anaerobic threshold (+2.3 ml/kg/min). Norepinephrine plasma level at rest was significantly lowered only by K-strophanthidin. Results were comparable when digoxin was given intravenously. We conclude that both glycosides elicit an increase of the inotropic cardiac state but only K-strophanthidin improves exercise performance.


[Importance of late reversibility in the identification of myocardial viability at risk after myocardial infarction]. The prevalence of late reversibility in single photon emission computed tomography (SPECT) thallium 201 stress/redistribution studies is still controversial. The aim of our work was to evaluate the prevalence of late reversibility at infarct site in an unselected population of patients with previous acute myocardial infarction (AMI). We studied by SPECT thallium 201 and pharmacologic stress with dipyridamole (DIP) as well as by two-dimensional echocardiography 58 consecutive patients with previous AMI (50 men of mean age 57 years, range 40-73; 8 women of mean age 58 years, range 50-68). All the patients with perfusion defect at infarct site that was persistent at 4-hour study, were reimaged after 24 hours. Twenty-one (36%) of 58 patients complained about postinfarction angina. Following intravenous DIP (0.56 mg/kg), heart rate increased from 67 +/- 14 to 83 +/- 14 b/min (< 0.0001) and diastolic and systolic arterial pressures dropped from 86 +/- 12 and 139 +/- 25 mmHg to 79 +/- 14 and 132 +/- 27 mmHg, respectively (< 0.0001; < 0.0005). Of 57 patients with stress perfusion defects at infarct site, 16 (28%) demonstrated reversibility after 4 hours and 19 (33.4%) after 24 hours, with a total of 35 (61.4%) patients demonstrating reversibility by combined 4-hour and 24-hour imaging (< 0.0001 versus reversibility at 4-hour imaging alone). Thus, of 41 patients with 4-hour persistent thallium defects at infarct site, 19 (46.3%) demonstrated late reversibility.(ABSTRACT TRUNCATED AT 250 WORDS)


[Early isovolumetric relaxation: correlation with the densitometric analysis of coronary stenosis]. Early relaxation is characterized by a segmental outward wall movement during isovolumic relaxation. There is still no general agreement as to its significance. Some Authors have considered the phenomenon to be a specific marker of isolated coronary narrowing, others have regarded it as a normal variation of left ventricular relaxation and still others concluded that it is a compensatory phenomenon to local ischemia in another region. We used a method of quantitative assessment of regional left ventricular function and a videodensitometric analysis of coronary stenosis. In our study we didn't observe an improved systolic function of the regions that presented early relaxation, but a slight non significant reduction. We did neither observe any correlation between early relaxation and ischemia provoked by stress test nor between early relaxation and coronary artery disease. The amplitude of early relaxation was not statistically different between patients with and without stenosis of left anterior descending artery. We conclude that early relaxation is a normal variation of left ventricular relaxation.


[Lipids and serum apoproteins in subjects with slight or mild coronary atherosclerosis evaluated with angiography]. In this study 126 subjects (91 males and 35 females, range of age 43-65 years) were studied by coronary angiography. We considered positive for coronary atherosclerosis also patients showing mild or moderate stenosis (> or = 25%). In all subjects we have evaluated serum lipid and apoprotein A-I, B, C-II, C-III and E levels; therefore also cholesterol concentrations in all lipoprotein fractions, separated by sequential ultracentrifugation (VLDL d < 1.006, LDL d 1.006-1.063, HDL d > 1.063 g/ml) and apoprotein B in LDL have been measured. Subjects with coronary atherosclerosis have shown significantly higher levels of total cholesterol, LDL-cholesterol, total cholesterol/HDL-cholesterol and LDL-cholesterol/HDL-cholesterol ratios than controls. Therefore, a lower apo A-I/apo B ratio in males and a higher LDL-apo B levels in females has been found in subjects with coronary atherosclerosis in comparison with controls. The stepwise multiple analysis has demonstrated that LDL-cholesterol levels is the parameter that best correlates with the presence of coronary atherosclerosis. These data confirm the importance of the reduction of LDL-cholesterol levels in primary and secondary prevention of coronary heart disease.


[The use of the inferior epigastric artery as alternative conduit for myocardial revascularization: our experience]. When complete revascularization can not be obtained with the internal mammary artery and saphenous veins, the inferior epigastric artery may be an excellent alternative conduit. We describe our experience with this conduit, review the anatomy of this artery, and present the evolution of our harvesting technique through a pararettal approach. Proximal anastomoses were made first with the aid of an oval cuff of the common femoral artery (5 cases, Group A). Two patients (40%) of this group studied postoperatively revealed a graft occlusion. In the last 13 cases (Group B) we tailored the proximal anastomoses directly to the aorta. All patients studied postoperatively showed patent inferior epigastric artery grafts. There were no hernias and no deaths. Inferior epigastric artery can be considered a good alternative conduit in myocardial revascularization.


[Phase 3 and phase 4 bundle of branch block]. Intermittent left bundle branch blocks are present in the ECGs of 1 patient with mitral valve disease. By occurring either after short or long cycles they represent respectively phase 3 and phase 4 blocks. Such mechanisms emphasize the relationship between automatism and conduction. The occurrence of block and of normal conduction during cycles of the same length, its correlation with the conduction of the previous cycle, demonstrate the presence of a functional linking between successive impulses. This linking may occur every time a potential or active macroreentry circuit exist. In our case the circuit is formed by the 2 bundle branches which join distally in the ventricular septum.


[Critical mitral stenosis in pregnancy: description of a case treated with percutaneous valvuloplasty]. We report the case of a 26-year-old woman who underwent mitral valvuloplasty during the 23rd week of gestation, following an episode of pulmonary edema. Dilation, performed without complications, increased mitral valve area from 0.9 to 1.8 cm2, cardiac output from 4.8 to 5.9 l/min, and decreased mean transvalvular gradient from 13.2 to 5 mmHg. The patient delivered spontaneously a full-term normal baby. Echocardiographic evaluation at 6 months confirmed the persistency of procedure's good outcome. According to some Authors and to our results it can be inferred that mitral valvuloplasty is a feasible and effective treatment for critical mitral stenosis during pregnancy.


The invention and reinvention of cardiac pacing. Two primitive pacemakers were invented between 1925 and 1932, demonstrating that adequate knowledge existed to pace the heart for brief periods. Heart specialists ignored these interesting inventions. In contrast, Zoll's announcement of external pacing in 1952 spurred intense interest and an outpouring of research. The reasons for the different response of heart specialists in the 1950s have to do with improved medical understanding of cardiac arrhythmias, growing confidence that cardiac resuscitation was possible, and the expansion of hospital-based medicine after World War II.


Cardiac pacing in special and complex situations. Indications and modes of stimulation. This article reviews a variety of pacing options for those patients with special and complex situations. Syndromes and syncopes, cardiomyopathy, and coronary artery disease are reviewed. Pacing modes are also discussed.


Timing cycles of permanent pacemakers.

Timing cycles of permanent pacemakers. A clear understanding of the components of the pacemaker timing cycles is crucial to understanding and interpreting paced electrocardiograms. The information given in this article provides basic rules for timing cycles for pacing modes currently in use and pacing modes less frequently used but of importance in understanding current timing cycles. Although understanding basic timing cycles allows interpretation of most paced electrocardiograms, manufacturer-dependent variations of the timing cycle operation make it necessary to be intimately familiar with the design of each pacemaker to be interpreted.


Cardiac pacing and atrial arrhythmias.

Cardiac pacing and atrial arrhythmias. Pacemaker patients frequently have concomitant atrial tachyarrhythmias, most importantly atrial fibrillation, because numerous underlying electrical or structural diseases can potentiate both conditions. DDD pacing (or atrial) appears superior to VVI in limiting the occurrence of atrial fibrillation and its associated negative sequela. Sick sinus syndrome, a prior history of atrial fibrillation, and advanced age predispose patients with DDD devices to postimplant atrial fibrillation, yet the majority of these high-risk patients are manageable in DDD throughout their follow-up. DDD patients at significant risk for developing atrial arrhythmias require special attention regarding the selection and programming of their devices. Rate modulation, higher lower rate limits, special approaches toward upper rate limit management, and antitachycardia capabilities may all be important aspects in their management. The combined use of AV node ablation and ventricular or DDD pacing to manage patients with refractory atrial tachyarrhythmias is becoming an increasingly accepted therapeutic approach.


Physiology of rate-responsive pacing.

Physiology of rate-responsive pacing. The search for a pacemaker that accurately and easily mimics normal physiology is a continuing effort. There have been many achievements in the past, including sensing of the pacing chamber and programming of the pacing rate, sensitivity, and output. Present pacing developments include atrioventricular synchrony and rate adaptiveness. Results of studies on activation sequence and circadian variations will impact future pacing. The usefulness, cost effectiveness, and clinical value of some of the new pacing features remain unclear. Further clinical trials are necessary to clarify the value of new pacing techniques.


Comparison of two activity-controlled rate-adaptive pacing principles: acceleration versus vibration. Activity-guided rate-adaptive pacing is currently the most widely used principle for rate adaptation. Broad experience has been gathered from several hundred thousand pacemakers that adjust the pacing rate according to vibrational forces detected by a piezosensor bonded to the inner side of the pacemaker can. A new generation of accelerometer-based pacemakers has been introduced into clinical practice. The vibrational type detects vibration, pressure, and shock waves traveling through the body with physical stress and using the pacemaker can as a resonator. In contrast, the accelerometer is insulated from the pacemaker housing and is incorporated into electronic hybrid circuitry. The forces detected by an accelerometer are motion and acceleration of the body in an anterior-posterior direction. Clinical studies conducted to date have shown that the accelerometer to be superior to the conventional vibration activity pacemakers, as far as the discrimination of different workloads and rejection of unwanted environmental noise are concerned.


Rate-responsive pacing using electrographic parameters as sensors. The use of evoked QT-interval and ventricular depolarization gradient as sensors for rate-responsive pacing is described in this article. The QT interval has been used as a biosensor in implantable pacemakers since 1981, and recent refinements have improved the rate response characteristics and simplified the programming of this pacemaker. Recently, QT and activity sensing have been combined to produce a dual-sensor rate-responsive pacemaker that may offer advantages over single-sensor devices. The ventricular depolarization gradient has been incorporated into a closed-loop rate-responsive pacing system and is undergoing clinical evaluation.


Adaptive-rate pacemakers. Comparison of sensors and clinical experience. Many types of artificial sensors for adaptive-rate pacing have appeared but as yet there is no single sensor that properly reflects metabolic demand under all circumstances. Several other types of sensors are currently evaluated. Combinations of different sensors in a single unit are very promising. At present, however, the only completely satisfactory sensor is the normal sinus node.


Survival in patients with permanent pacemakers. Atrioventricular block I has a benign natural course, and permanent pacing is not warranted. Second-degree AV block, including both type I and type II, can have an ominous course, especially in older patients with underlying heart disease. One study claims that the prognosis in patients with second-degree AV block, irrespective of type, is improved by permanent pacing. In spite of lack of controlled studies it has been convincingly shown that VVI pacing prolongs life in patients with high-grade AV block. Two studies suggest that atrial synchronous pacing in patients with congestive heart failure and high-grade AV block might improve their survival. Studies comparing survival with different pacing modes in patients with sinus node disease support the hypothesis that physiologic pacing can improve survival. Prophylactic pacemaker implantation even in symptomatic patients with chronic bifascicular block does not seem to protect them from sudden death.


Exercise testing for chronotropic assessment. Cardiac chronotropic analysis has only begun to develop into a clinically relevant science. In the past, formal exercise testing was usually relegated to the assessment of ischemia or cardiac rehabilitation. The establishment of rate-responsive pacemakers as a potentially effective treatment for chronotropic incompetence forced the definition of cardiac chronotropism and assessment of the pacemaker response. Little is known about the normal chronotropic response and less has been established about patients with ventricular dysfunction or ischemia, but standards are being set and modern pacemakers have produced the ideal clinical laboratory for investigation. Advanced telemetry, including sensor and actual rate trends, histography and sensorgraphy produce previously unobtainable clinical data. Now scientific inquiry demands that chronotropic evaluations seek to match the pacemaker-augmented response of the chronotropically incompetent patient to the metabolic requirements of the body. Only with formal exercise testing will this goal be achieved.


Strategies for mode selection in antibradyarrhythmia pacing. A systematic technique is described for selecting an appropriate mode of antibradycardia pacing on the basis of 10 clinical criteria. A computer model of the selection process was developed with input from more than 41 implanting physicians, and implemented together with a database management system for keeping track of mode selections and identifying cases in which the modes selected by the implanters differed from those recommended by the model. The selection technique, which can be used without a computer, is presented in detail with a decision-tree representation of the model and an explanation of the rationale behind each of its 39 possible recommendations.


Lead extraction. Indications and techniques. Each of the extraction techniques and their ancillary tools was reported as used successfully; however, until now, no technique has been successful when used in more than a few isolated instances. The technique for intravascular countertraction and the associated tools described in this paper were devised and selected in an attempt to develop one technique to be used on all patients, with all types of leads, and with a very low complication rate. Its versatility permitted single or multiple lead extractions combined with the precision of selecting and extracting a specific lead. In our experience, as well as the experience of others, the techniques described in this paper have proved to be superior by minimizing the inherent risk and morbidity, allowing us to expand the indications for lead removal beyond septicemia and free-floating leads, to include infection, abandonment of pockets, and replacement of malfunctioning or fractured leads. Intravascular countertraction was a consistently safe and efficacious method of removing transvenous pacemaker leads regardless of the duration of the implant, thus permitting extractions in patients not considered candidates for a more extensive surgical procedure. Intravascular countertraction encompasses surgical and fluoroscopic techniques possessed by most physicians experienced in pacemaker and automatic implantable cardioverter defibrillator implants. However, there is a learning curve, predicating caution for the inexperienced physician. In addition, advanced surgical skills may be needed in handling associated conditions such as debridement and primary closure of chronically inflamed tissues, especially in submuscular pockets and sinus tracts in the neck. Although the potential for a cardiovascular complication is small, it does exist, and cardiovascular surgical backup is a recommended precaution.


Pediatric cardiac pacing.

Pediatric cardiac pacing. Cardiac pacing in children has undergone many improvements in the last decade. The differences between adult and pediatric pacing have narrowed. Children are no longer being denied pacemakers because of size. This article discusses techniques for pacing pediatric patients successfully that will allow them to lead normal lives.


Historical overview on the development and characteristics of stents and future outlooks. The history and development of endovascular stents is described beginning with the Maass double helix spiral prosthesis, the first stent used in human clinical trials in the early 80s. This is followed by a description of the three main groups of stent techniques: the shape memory alloy stents, the balloon-expandable stents, and the self-expanding stainless steel stents. Requirements and new trends for improving clinical results in the future complete this text.


Intravascular stenting: from basic research to clinical application. Although the use of intravascular stents is approaching widespread clinical use, several questions remain regarding their safety and efficacy. Several factors have direct bearing on the immediate and long-term results of intravascular stenting. The technical results of stenting are dependent on the mechanical characteristics of the device and long-term patency is closely related to thrombogenicity and endothelialization. Although stents are used most frequently for the treatment of atherosclerotic disease there is no clear understanding of how they influence the atheromatous lesion.


Stent placement in iliac arterial lesions: three years of clinical experience with the Wallstent. Within a 3-year period, 125 patients with 63 iliac occlusions and 62 complex iliac stenoses underwent stent placement using self-expandable vascular endoprostheses. Early technical success rate was 98%, with a total complication rate of 4%. Major complications were seen in 1.6%. Early reobstruction occurred in 4 patients with previous occlusions. Late reobstruction due to a clinically relevant restenosis or reocclusion occurred in 10 patients and required 12 repeat interventional procedures. Cumulative patency, excluding early technical failure, was 100% at 6 months and 89.4% at 24 months. Stenting of iliac arteries using self-expandable endoprostheses is a safe and effective treatment of complex iliac lesions.


Stenting of the iliac arteries with the Palmaz stent: experience from a multicenter trial. Balloon-expandable, intraluminal stenting of the iliac arteries with the Palmaz stent was the subject of a multicenter study for 4 years. A total of 486 patients underwent 587 procedures. Four hundred and five patients had unilateral and 81 had bilateral iliac stent placements. Follow-up ranged from 1 to 48 months (mean 13.3 +/- 11 months). Sustained clinical benefit of the treated patients was obtained in 90.9% at 1 year, 84.1% at 2 years, and 68.6% at 43 months. Angiographic patency rate was 92%. Diabetes mellitus and poor runoff had significant negative influence on the clinical outcome. The 10% incidence of procedural complications was not altered by operator experience.


The Strecker stent: indications and results in iliac and femoropopliteal arteries. We have implanted more than 100 Strecker stents in the iliac and femoral arteries. In iliac arteries, follow-up is available from 8 to 48 months (mean 20 months) and in peripheral arteries, from 8 to 32 months (mean 19 months). In iliac and proximal femoral arteries there was a patency rate of 98% (mean 20 months after stent implantation) whereas in peripheral arteries the patency rate was 70.8% (mean 19 months after stent implantation). Besides careful selection of patients, anticoagulation is very important for successful stenting. Because of the excellent results of stents in iliac vessels there is a wide range of good indications, including primary stenting after recanalization of occlusions. In contrast, stent implantation in peripheral vessels should be restricted to special cases such as acute dissection or reocclusion after successful recanalization.


Gianturco-Rösch expandable Z-stents in the treatment of superior vena cava syndrome. Gianturco-Rösch expandable Z-stents were used in 22 patients with superior vena cava syndrome (SVCS). Stents were placed in all patients in the SVC and in 17 patients, also into the innominate veins. Stent placement resulted in complete relief of symptoms in all patients. Twenty-one patients had no SVCS recurrence from 1 to 16 months, to their death, or to the present time. SVCS recurred only in 1 patient 9 months after stent placement due to tumor ingrowth and secondary thrombosis. Based on ours and on other reported experiences, expandable metallic stents are effective devices for treatment of the SVCS which is difficult to manage by other means.


Gianturco self-expanding stents: clinical experience in the vena cava and large veins. Twenty-five patients with stenosis of the vena cava (21) and other large veins (4) have been treated with self-expanding Gianturco metallic stents. Eighteen patients had superior vena cava syndrome. In 17, the stricture was due to malignant superior vena cava compression recurrent after maximum tolerance radiotherapy and/or chemotherapy. In 16 of these patients there was early symptomatic relief. In 1 patient with a benign posttraumatic superior vena cava stricture, the stenosis was not relieved, and occlusion occurred after 1 month. Stenoses associated with dialysis shunts were relieved in 2 other patients. Two malignant and one benign inferior vena cava stenoses were relieved either until death, or in the benign case, for 30 months. One malignant subclavian vein obstruction occluded after 24 h due to stent misplacement and another with extrinsic mediastinal compression remained patent until death, extensive thrombus having been lysed prior to stent placement. The results of this short series suggest that the Gianturco self-expanding stent in the vena cava and large veins is easy and safe to place, and in most cases produces almost immediate palliation of the distressing effects of venous obstruction, often in a preterminal and inoperable patient.


Use of the Wallstent in the venous system including hemodialysis-related stenoses. Eighteen patients with a total of 23 venous stenoses or occlusions were treated with the Wallstent. In 5 patients treated for malignant stenosis there was one primary failure due to insufficient stent expansion. The other 4 patients showed rapid relief of their inflow obstruction, all remaining asymptomatic despite later stent occlusion in 1 patient. Four patients were treated for benign postoperative stenoses of the iliac or femoral vein. All stents remained patent for a period of 6 weeks-58 months. Nine patients were treated for one or multiple stenoses along the venous outflow tract of hemodialysis fistulas. Of 14 lesions that were eventually stented, 12 are still patent after 3-27 months (mean 19). However, 10 secondary interventions (eight percutaneous transluminal angioplasty (PTA), two stents) and three additional stent procedures for new lesions were necessary. Although our experience is limited, we believe that patients with tumor compression or postoperative strictures of large veins benefit from treatment with stents. Stenting of venous outflow stenoses in hemodialysis fistulas can significantly prolong stent function, however, PTA should always be the first treatment of choice.


A comparison study of self-expandable stents vs balloon angioplasty alone in femoropopliteal artery occlusions. In a group of 26 patients percutaneous transluminal (balloon) angioplasty (PTA) and stents (Wallstents) were applied and in another 26 matched patients PTA alone was used as primary treatment for femoropopliteal occlusions of 3 cm or longer. Five patients with stents showed early thrombosis necessitating catheter thrombolysis and/or thrombus aspiration. Ten patients had recurrent stenoses within 12 months, mostly due to neointimal hyperplasia. Following three late catheter reinterventions, a cumulative secondary patency rate of 69% was achieved after 12 months. The group of patients treated by PTA alone showed a 12 months patency rate of 65% without reinterventions. In 8 other patients, stents were inserted for recurrent obstructive or PTA-resistant lesions, and similar results as with the stents above were obtained. Thus, these stents do not improve primary results of PTA in femoropopliteal occlusions but may be useful secondarily after unsuccessful PTA.


Morphologic and clinical results of the transjugular intrahepatic portosystemic stent-shunt (TIPSS). The concept of transjugular intrahepatic portosystemic stent-assisted shunt (TIPSS) using the Palmaz iliac stent has been successfully accomplished in 18 of 24 patients representing a technical success rate of 75%. Fourteen were male, 4 female with a mean age of 60 years (range 34-84 years). According to classification of Child's and Turcotte, 6 were in stage A, 6 in stage B, and 6 in stage C. Five patients were treated on an emergency basis because of massive active bleeding. In 10 patients the portosystemic tract was created between the middle hepatic vein and the right main stem of the portal vein in 8, and the left main stem in 2 patients. In 8 patients, the shunt was established between the right hepatic vein and the right main branch of the portal vein. The portosystemic gradient in 18 patients was 29.9 +/- 6 mm Hg and dropped to an average of 16.9 +/- 4 mm Hg after shunt establishment. Within the early postprocedural period of 30 days, 1 patient died of direct complications of the procedure. Because of catheter dislocation, embolization of the percutaneous transhepatic approach to the portal vein after successful shunt "creation" could not be done and was followed by intraabdominal exsanguination. One patient died of an ARDS after TIPSS. A third developed pulmonary infection. In 13 patients, because of hematomas at the puncture site of the transhepatic approach, only the transjugular approach was elected for establishing TIPSS.(ABSTRACT TRUNCATED AT 250 WORDS)


Midterm results of renal artery stenting. Percutaneous transluminal angioplasty (PTA) has become the treatment of choice for major renal artery stenosis. Nonetheless, about 10% of renal artery stenoses cannot be properly dilated, and among the patients successfully dilated, 10%-15% had a recurrence. Renal artery stenting was used in 21 patients in cases of insufficient results after PTA: persisting significant stenosis after a primary or several PTAs (15 cases), recurrences (9 cases). Follow-up in all patients was from 12 months to 4 years. Implantation was performed without any problems but the low radioopacity of the stent makes placement difficult in obese patients, particularly for ostial lesions. There was no major complication except occlusion of a segmental branch of the renal artery in 1 case. Radiological controls have shown a preserved patency in all cases except 2, which present restenosis inside the stent by intimal hyperplasia. A significant clinical improvement was obtained in 90% of cases. These results suggest that the endovascular prosthesis represents an important adjunct to renal PTA.


Functional implications of spontaneous sarcoplasmic reticulum Ca2+ release in the heart. The Cai oscillation generated by the sarcoplasmic reticulum in response to an action potential occurs relatively synchronously within and among cells. The sarcoplasmic reticulum can also generate spontaneous Cai oscillations (S-CaOs), ie, not triggered by sarcolemmal depolarisation. The local increase in Cai due to S-CaOs is equivalent to that induced by an action potential. Heterogeneity of diastolic Cai among cells within myocardial tissue caused by asynchronous S-CaOs leads to heterogeneous myofilament activation, the summation of which produces a Ca2+ dependent component to diastolic tone. The local increases in Cai due to S-CaOs also cause oscillatory sarcolemmal depolarisations due to Ca2+ modulation of the Na-Ca exchanger and of non-specific cation channels. When local S-CaOs within a myocardial cell is sufficiently synchronised the resultant depolarisation summates and can be sufficient to trigger a spontaneous action potential. Inhomogeneous levels of diastolic Cai among cells may lead to heterogeneity in cell coupling and thus may also affect the impulse conduction in myocardial tissue. The magnitude of the S-CaOs induced diastolic tonus and depolarisation varies with the extent to which S-CaOs are synchronised; partially synchronised S-CaOs following an action potential induced Ca2+ release produce an aftercontraction and afterdepolarisation. Inhomogeneity of diastolic sarcoplasmic reticulum Ca2+ loading and sarcomere lengths within individual cardiac cells due to S-CaOs leads to inhomogeneous systolic Cai levels and sarcomere inhomogeneities in response to a subsequent action potential, which compromise the systolic contraction amplitude. Heterogeneity of systolic Cai among cells due to diastolic S-CaOs also leads to heterogeneity of action potential repolarisation times, due to heterogeneous Cai modulation of the Na-Ca exchanger, the non-specific cation channel, the L type Ca2+ channel and, depending upon species, Ca2+ activated K+ channels. S-CaOs occurrence during a long action potential plateau may also modulate the removal of voltage inactivation of L type Ca2+ channels, and affects the likelihood of the occurrence of "early afterdepolarisations." Thus, as a single entity, S-CaOs may be implicated in diverse manifestation of heart failure--impaired systolic performance, increased diastolic tonus, and an increased probability for the occurrence of arrhythmias.


Differential effects of left anterior descending coronary occlusion on left and right ventricular anterior wall thickening in the conscious pig. In humans, the left anterior descending coronary artery supplies the left ventricular wall, anterior septum and the paraseptal part of the right ventricular anterior wall. Our aim was to study the effects of acute left anterior descending coronary occlusion on wall thickening in the regions of the left and right ventricular anterior walls supplied by the artery, and in remote, non-ischaemic regions of both ventricles. Systolic wall thickening (defined as percent thickening with respect to end diastolic wall thickness) was studied in eight conscious pigs every 15 s during 1 min of acute left anterior descending coronary occlusion by a cuff occluder, and every 30 s during 4 min of reperfusion. Pigs were instrumented with ultrasonic microcrystals measuring wall thickness in the anterior walls (left anterior descending artery territory) and lateral walls (left circumflex or right coronary artery territory) of both ventricles, and a left ventricular pressure microtransducer. During control and reperfusion, both anterior walls displayed similar systolic thickening. During coronary occlusion, the left ventricular anterior wall showed paradoxical systolic thinning (dyskinesia) whereas the right ventricular anterior wall showed only hypokinesia. In the presence of equal blood flow deprivation, the right ventricular anterior wall supplied by the left anterior descending coronary artery displays a significantly lesser degree of functional impairment than the left ventricular anterior wall supplied by the same artery. This differential effect may be due to mechanical unloading of the right ventricular anterior wall resulting from left ventricular anterior wall ischaemia. This afterload reduction due to decreased mechanical interaction between the two walls would allow the right ventricular anterior wall to express its contractile reserve in the form of systolic thickening.


Cardioprotective effects of ischaemic preconditioning are not mediated by prostanoids. Some reports have suggested that the mechanism of ischaemic "preconditioning" is mediated through prostacyclins. In this study the hypothesis that the cardioprotective effect of preconditioning is due to the synthesis and release of prostaglandin/prostacyclin was tested by assessing whether aspirin, an inhibitor of cyclo-oxygenase, could block or prevent the protective effect of preconditioning. In protocol I, three groups of rats were studied. (1) CONTROL: rats received 90 min of coronary occlusion followed by 4.5 h of reperfusion (n = 8). (2) Preconditioning: hearts were preconditioned by three repeated episodes of 3 min of coronary occlusion and 5 min of reperfusion, and then subjected to 90 min of occlusion followed by 4 h of reperfusion (n = 9). (3) Aspirin + preconditioning: aspirin (10 mg.kg-1) was given 10 min prior to the preconditioning. Rats then underwent preconditioning and occlusion/reperfusion as in group 2 (n = 8). In protocol II, two groups were studied. (1) CONTROL: rats received 90 min of occlusion and 4.5 h of reperfusion (n = 6). (2) Aspirin + single occlusion: aspirin (10 mg.kg-1) was given 10 min prior to the 90 min occlusion, and then rats underwent occlusion/reperfusion as in controls (n = 6). Female Sprague-Dawley rats weighing between 235-500 g were used. Planimetry was used to measure area at risk (AR) following blue dye injection and area of necrosis (AN) after tetrazolium staining. Protocol I: all three groups had comparable AR. AN/AR was reduced significantly (p less than 0.05) in both the preconditioning group [29.6(SEM 7.6)%] and the aspirin + preconditioning group [29.6(8.7)%] compared with the control group [59.3(3.4)%]. The incidence of ventricular tachycardia and/or fibrillation was also reduced in both the preconditioning and the aspirin + preconditioning groups. Protocol II: the area at risk, area of necrosis, and the indicence of ventricular arrhythmia were not significantly different between aspirin + 90 min occlusion and control groups. Preconditioning both with and without aspirin significantly reduced infarct size and the incidence of ventricular tachycardia and/or fibrillation. As the effects of preconditioning were not prevented by aspirin, this suggests that the cardioprotective effects of preconditioning are not mediated by prostanoids in the rat model.


Deleterious cardiac effects of captopril during acute myocardial ischaemia in the dog. The aim was to evaluate the effects of the angiotensin converting enzyme inhibitor captopril on acute myocardial ischaemia. Seventeen anaesthetised open chest dogs were randomised to 3 minute angioplasty balloon occlusions of the left circumflex coronary artery before and after intravenous infusion of captopril (n = 8) or placebo (n = 9). There was apparent worsening of ischaemia during balloon inflation after captopril infusion, when compared with control inflation, as suggested by further ST segment elevation of 1.8 (SD 1.8) mm, p less than 0.03, and by further lowering of regional myocardial pH [-0.05(0.05), p = 0.06], and peak positive and peak negative dP/dt [-439(337)mm Hg.s-1, p less than 0.008; -470(316) mm Hg.s-1, p less than 0.004, respectively]. The increase in ischaemia occurred despite reduced double product after captopril administration. Regional myocardial blood flow in the ischaemic artery distribution was lower during post captopril balloon occlusion [-0.1(0.06) ml.min-1.g-1, p less than 0.005] than during control balloon inflation, while coronary vascular resistance increased by 161(172)% (range 45 to 497%, p less than 0.04). There were no significant differences in ST segments, pH, haemodynamic variables, or blood flow during balloon inflations before and after saline infusion. Despite lower myocardial metabolic demands, acute intravenous administration of captopril was associated with increased ischaemia during transient coronary artery occlusion.


Local activation variability during monomorphic ventricular tachycardia in the dog. The aim was to determine the beat to beat variability in local activation time during sustained monomorphic ventricular tachycardia in a canine model of experimental myocardial infarction. A digital template matching algorithm was developed for detecting subtle beat to beat variability in local activation timing at each of multiple ventricular sites. Ten electrically induced sustained ventricular tachycardia episodes, mean cycle length 211 (SD 40) ms, were endocardially and epicardially mapped in mongrel dogs weighing 15-20 kg. Digitised data were analysed for beat to beat local activation time variability. Similar data recorded during ventricular pacing at comparable rates and during sinus rhythm served as controls. The overall mean variability of local activation time for all 10 ventricular tachycardias was 3.2(1.6) ms, range 1.8(1.1) ms to 4.7(2.8) ms, in contrast to the overall mean variability of 0.2(0.4) ms (p = 0.0001) for ventricular pacing and 0.7(0.6) ms (p = 0.0001) for sinus rhythm. Oscillations in local activation time manifested alternans type periodicity during seven of 10 ventricular tachycardias independent of any alternans in local electrogram morphology. During sustained, monomorphic ventricular tachycardia, beat to beat variability and alternans type oscillations in local activation time are common and may be an intrinsic property of re-entry since they are negligibly small during ventricular pacing.


Role of anisotropy in determining the selective action of antiarrhythmics in atrial flutter in the dog. The aim was to clarify the electrophysiological and anatomical features of the preferential site of action of antiarrhythmic drugs in the re-entrant circuit of canine atrial flutter. Electrophysiological and anatomical findings were correlated in 17 anaesthetised adult mongrel dogs with atrial flutter associated with an intercaval anatomical obstacle, before and after intravenous administration of disopyramide (2 mg.kg-1) and flecainide (2 mg.kg-1). Before drug injection, a rate dependent prolongation of conduction time occurred in the low right atrium where the conduction was slow during atrial flutter. Disopyramide (n = 8 dogs) and flecainide (n = 9 dogs) terminated atrial flutter, with conduction block occurring in this slow conduction area in the low right atrium. Although the degree of drug induced prolongation of refractoriness in this particular area was similar to those in other areas of the right atrium, conduction was depressed to a greater extent in this region. Anatomical study revealed that a thick pectinate muscle that branched from the crista or crista terminalis itself ran perpendicular to the wavefront of the pacing impulse and atrial flutter in this slow conduction area. These data indicated that slow conduction might be attributed, at least in part, to anisotropic conduction over the thick muscle bundle in the low right atrium, and that antiarrhythmic drugs preferentially produced conduction block in this area. Anisotropic conduction in the low right arium is an anatomical substrate for slow conduction in the re-entrant circuit and for the site preference of antiarrhythmic drugs in the present canine model.


Effects of regional ischaemia, with or without reperfusion, on endothelium dependent coronary relaxation in the dog. The aim was to establish whether the duration of coronary ischaemia and coronary ischaemia with reperfusion selectively reduced the magnitude of relaxation mediated by endothelium dependent relaxing factor (EDRF) in response to thrombin, compared with relaxation produced by acetylcholine and calcimycin. Adult male dogs, anaesthetised with sodium pentobarbitone (30 mg.kg-1 intravenously) were used. Coronary artery occlusions were maintained for either 15 or 45 min; in half the dogs from each timepoint, occlusion was followed by 60 min reperfusion. At the end of each in situ period, coronary arteries were removed from both ischaemic and non-ischaemic regions, cut into rings, and hung in isolated organ baths. Dose-response relationships to the EDRF dependent vasodilators thrombin, acetylcholine, and calcimycin, and to the EDRF independent vasodilator isoprenaline, were then established. Thrombin (0.003-0.3 units.ml-1) caused dose dependent relaxation in all tissues. Relaxant responses (E(max)) in the non-ischaemic vessels from both 15 and 45 min treatment groups were used as control data for the responses in ischaemic vessels. Maximum responses were not different in the non-ischaemic groups from either 15 or 45 min studies, at 82.7 (SEM 3.7)% after 15 min, and 82.1(2.4)% after 45 min. There was a small but significant reduction in E(max) after 15 min and 45 min ischaemia, to 74.4(3.2)% and 74.4(3.0)% respectively. Sixty minutes reperfusion provoked a further reduction in E(max) to 64.9(3.8)% after 45 min ischaemia, but not after 15 min ischaemia [70.3(4.2)%]. Neither 15 nor 45 min interventions altered E(max) of relaxation to acetylcholine or calcimycin (greater than 88.0% in each group). Similarly there were no significant differences between groups to the relaxation stimulated by isoprenaline (E(max) greater than 90.0%). The data suggest that loss of EDRF dependent relaxation to thrombin is more sensitive to ischaemia than the relaxation produced by either acetylcholine or calcimycin, and appears to be manifested early in the onset of ischaemic injury.


Nitric oxide does not mediate flow induced endothelium dependent arterial dilatation in the cat. The aim was to determine whether the endothelium derived nitric oxide formed from L-arginine is the factor which mediates flow induced dilatation of conduit arteries. Changes in diameter of feline femoral artery caused by blood flow rate increases, acetylcholine, and ATP were recorded during perfusion with blood in situ before and after the inhibition of endothelium derived nitric oxide synthesis by NG-nitro-L-arginine methyl ester and NG-monomethyl-L-arginine. Fourteen anaesthetised cats of either sex, weight 2.6-3.9 kg, were used for the studies. Intravenous administration of NG-nitro-L-arginine methyl ester and NG-monoethyl-L-arginine in doses 10 and 30 mg.kg-1 evoked a rise in mean systemic arterial pressure, constriction of the femoral artery, and considerable decrease in acetylcholine and ATP induced dilatation. However, it did not affect the dilator response induced by increased blood flow rate. Flow induced endothelium dependent arterial dilatation is not mediated by nitric oxide or, if nitric oxide is still released in response to flow rate increase, it has a source distinct from L-arginine.


Decreased hypothalamic and medullary GABA turnover in spontaneously hypertensive rats. The aim was to assess whether Gamma-aminobutyric acid (GABA) neurone activities in the central nervous system, especially in the hypothalamus and medulla oblangata, are altered in hypertension. Central GABA content and turnover rate were measured in spontaneously hypertensive rats (SHR) and their normotensive Wistar Kyoto controls (WKY). GABA content was determined with high performance liquid chromatography, and in vivo GABA turnover rates were estimated by GABA accumulation after injection of amino-oxyacetic acid, a selective inhibitor of GABA degrading system. Two groups of nine week old male rats (32 SHR and 32 WKY) were used. GABA concentrations in cerebrospinal fluid were lower in SHR than in WKY. Since hypothalamus and medulla oblongata are the possible active sites of this system, basal GABA contents and in vivo GABA turnover rates were measured in hypothalamus and medulla oblongata. Basal GABA content in the medulla oblongata and hypothalamus was almost equal in SHR and WKY. On the other hand, GABA turnover rates were significantly lower in SHR than in WKY in both the hypothalamus and the medulla. Since it is known that GABA is an inhibitory neurotransmitter in the central nervous system and that it controls autonomic and cardiovascular activities, the findings suggest that the decreased hypothalamic and medullary GABAergic activities may permit sympathetic hyperactivity to contribute to the increase in blood pressure in SHR.


Aortic input impedence and neurohormonal activation in patients with mild to moderate chronic congestive heart failure. The aim was to investigate the interrelation between pulsatile components (assessed by determination of aortic input impedance) and neurohormonal activation in chronic congestive heart failure. Aortic input impedance, plasma noradrenaline, renin, atrial natriuretic factor, and arginine vasopressin were measured in 20 patients with mild to moderate chronic congestive heart failure (coronary artery disease n = 12, idiopathic dilated cardiomyopathy n = 8). Cardiac index [2.2(SEM 0.3) litre.min-1.m-2] and left ventricular ejection fraction [38(4)%] were reduced, and pulmonary wedge pressure was increased [21(2) mmHg]. Plasma concentrations of noradrenaline [462(62) pg.ml-1], renin [12(4) ng AI.ml.h-1], atrial natriuretic factor [408(64) pg.ml-1], and--to a slight degree--arginine vasopressin [1.1(0.3) pg.ml-1] were increased. Characteristic impedance Zc [80(6) dyne.s.cm-5) and relative oscillatory aortic input pressure power [10(1)%]--both reflecting the pulsatile components of left ventricular afterload--were within the normal range. There was no significant correlation between these variables and the degree of neurohormonal activation (r values: -0.05 to -0.35). The data show that in patients with mild to moderate chronic congestive heart failure there is no interrelationship between the degree of neurohormonal activation and pulsatile components of left ventricular afterload. This may indicate that in these stages of heart failure there are no trophic effects of stimulated neurohormonal systems on the physical properties of the great arteries.


Compensatory subendocardial hyperkinesis in the cat is abolished during coronary insufficiency outside an acutely ischaemic region. The aims were to determine (1) whether acute coronary occlusion provoked uniform hyperkinesis in remote non-ischaemic myocardium, and (2) how subsequent coronary stenosis affected such hyperkinesis. Two pairs of ultrasonic crystals were placed in the anterior left ventricular midwall of nine pentobarbitone anaesthetised open chest cats. One pair (longitudinal) ran parallel to subendocardial fibres; the other pair (circumferential) was aligned with subepicardial and mid-myocardial fibres. Following circumflex coronary occlusion, subsequent hypoperfusion of the anterior wall was established by controlled constriction of a shunt line from the right subclavian artery to the left main coronary artery in two discrete steps. Following circumflex occlusion maximum systolic shortening of segments aligned to subendocardial fibres increased from 6.7(SEM 0.9)% to 11.5(1.4)% (p less than 0.001), whereas circumferential segment shortening was unchanged, at 12.2(0.8)% v 14.1(1.1)%. During mild shunt stenosis [delta P = 42(2) mm Hg] subendocardial tissue blood flow in the anterior wall decreased by 42(10)% (p less than 0.001), and longitudinal segment shortening decreased from 11.5(1.4)% to 6.9(1.1)% (p less than 0.001). Corresponding shortening of circumferential segments did not change. During severe shunt stenosis [delta P = 52(3) mm Hg] subendocardial tissue blood flow decreased further, and shortening of longitudinal segments approached zero value (p less than 0.001). Compensatory hyperkinesis of remote non-ischaemic myocardium following an acute coronary occlusion may depend mostly on augmented subendocardial contraction.


Dispersion of coronary artery thrombi by antagonism of platelet serotonin receptor in the dog. Blockade of platelet 5HT2 receptors prevents coronary artery thrombi. This study explores the dispersal of established thrombus by such 5HT2 antagonism. Seven open chest anaesthetised beagles were used in a repeated measures study of the action of MDL 11,939 to remove the participation of platelet 5HT2 receptors in the natural history of intracoronary thrombosis with cyclic blood flow reduction. Endothelial damage and critical diameter constrictors were applied to the circumflex coronary artery, and systemic blood pressure and circumflex blood flow were measured continuously. Cyclic flow reductions, which were established by build up and embolisation of platelet thrombi, were completely abolished by the 5HT2 antagonist MDL 11,939. The dose given in the first two experiments was 0.5 mg.kg-1, reduced to 0.2 mg.kg-1 for the third. Subsequent animals received 0.1 mg.kg-1. Mean blood pressure rose slightly. Adrenaline infusion at 0.4 micrograms.kg-1.min-1 failed to restore cyclic flow reductions in any animal and caused a small flow increase without affecting mean blood pressure. The pattern of blood flow restitution after administration of MDL 11,939 was of great interest. In all the animals flow spontaneously increased in a stepwise fashion (a double step in five dogs). The step up was markedly different from the increase in flow seen during adrenaline infusion. (1) These results are further evidence of the importance of serotonin as a mediator of platelet thrombus in stenosed coronary arteries. (2) The apparent dissipation of thrombi by MDL 11,939 may be of importance.


The oxygen free radical system: from equations through membrane-protein interactions to cardiovascular injury and protection. Highly toxic oxygen radicals and their metabolites have been implicated in the pathogenesis of ischaemia/reperfusion injury. These reactive oxygen species include the superoxide anion, hydrogen peroxide, hydroxyl radical, and singlet oxygen. The central theme of this review is first to discuss the basic mechanisms of free radical generation from various potential sources, to point out and emphasise the growing importance of the role of singlet oxygen, and then to discuss in depth membrane-protein interactions that ultimately lead to myocardial damage and dysfunction. With this background, we highlight several novel therapeutic strategies aimed at interrupting the oxygen free radical mediated component of ischaemia/reperfusion injury. It is hoped that this thesis will then serve as a future impetus to challenge these hypotheses and further build on this truly unique system that has assumed such an important role in the pathophysiology of myocardial ischaemia/reperfusion and inflammation. "To those of us who are humbly exploring the mysteries of science, we must project our findings and model our systems. For if correct, we have made a small contribution and, if wrong, we have forced others to eventually think." A V Hill, on the occasion of the 50th anniversary of E H Starling's Linacre lecture (University College, London, 1968).


The L type calcium current in single hypertrophied cardiomyocytes isolated from the right ventricle of ferret heart. The aim was to study L type calcium current alterations in relation to the action potential lengthening induced by hypertrophy in isolated cardiomyocytes from the right ventricle of ferret. Chronic pulmonary artery constriction was established in adult male ferrets under anaesthesia. Sham operated animals were used as controls. Four to six weeks later the heart was excised and treated with a mixed collagenase-elastase solution to isolate the right ventricular myocytes. The calcium current was investigated in control and hypertrophied cells with the whole cell configuration of the patch clamp technique. The validity of the model was tested by analysis of the structural and passive electrical characteristics of the cells, which were enzymatically isolated from right ventricles previously overloaded (4 to 6 weeks) by clipping the pulmonary artery. Isolated cells from right ventricles submitted to a chronic pressure overload had well preserved cellular integrity suggesting the absence of myocardial failure. This compensated form of hypertrophy was characterised by a dilated transverse tubular system, which could explain the increased membrane capacity. Such cells developed a prolonged action potential with a less pronounced fast repolarisation phase inducing a higher plateau phase. When studied in physiological Tyrode solution the density and kinetics of the L type calcium current were not apparently modified, but a significant decrease in density was unmasked when sodium and potassium currents were suppressed by external and internal substitution of sodium and potassium by tetraethyl ammonium. The decrease in L type calcium current cannot be involved in the lengthening of action potential observed on hypertrophied myocytes, but it could account for the depressed contractile activity. A noticeable decrease of the transient outward current is suggested to explain the action potential alterations.


Reactive and reparative myocardial fibrosis in arterial hypertension in the rat. Myocardial fibrosis is an important determinant of pathological hypertrophy. In two experimental models of arterial hypertension the purpose of the study was (a) to determine total collagen volume fraction and relative contribution of scarring and perivascular/interstitial fibrosis; and (b) to assess the effects of the aldosterone receptor antagonist spironolactone on these patterns of fibrosis. 76 eight week old Sprague-Dawley rats weighing 180 to 200 g were used for the studies. Using videodensitometry total collagen volume fraction was separated into the various components for the left and right ventricles in the following experimental models: renovascular hypertension occurring following unilateral renal ischaemia; continuous aldosterone administration via osmotic minipumps with either high (AL) or low (ALLO) sodium diet; renovascular hypertension and AL after pretreatment and continuous treatment with either 20 or 200 mg.kg-1.d-1 subcutaneously of the competitive aldosterone receptor antagonist spironolactone. All groups were compared to age and sex matched controls. After eight weeks, systolic pressure was comparably increased in renovascular hypertension and AL and it remained raised with low dose spironolactone treatment in either model, but was normal with high dose spironolactone or low sodium diet. Left ventricular hypertrophy, expressed as a significant increase in left to right ventricular weight and left ventricle to body weight ratios, was present in renovascular hypertension, AL, and AL + low dose spironolactone compared to control (p < 0.005). In either ventricle: (1) the amount of interstitial/perivascular fibrosis and myocardial scarring was increased (p < 0.005) in renovascular hypertension and AL compared to control; (2) each was reduced (p < 0.005) with either dose of spironolactone; and (3) only scars were seen in ALLO. Myocardial fibrosis of either ventricle was comparable in renovascular hypertension and AL. Spironolactone was able largely to prevent the perivascular/interstitial fibrosis and scarring in either model irrespective of the development of left ventricular hypertrophy and arterial hypertension. Low sodium diet in hyperaldosteronism prevented hypertension and left ventricular hypertrophy, but not scarring. These findings suggest that a rise in plasma aldosterone, relative to sodium intake, may play a role in mediating collagen accumulation in the heart during the development of experimental arterial hypertension.


Effect of transmural vagal stimulation on electrotonic current spread in the rabbit sinoatrial node. The effect of vagal stimulation on the decay of electrotonic potential caused by intracellular current injection and on input resistance was measured in the sinoatrial node of isolated rabbit right atria. Studies were performed on New Zealand White rabbits weighing approximately 2-3 kg. Vagal stimulation was achieved by transmural stimulation of intramural nerve fibres in the presence of propranolol. A K+ perfused suction electrode was used to inject hyperpolarising current pulses; input resistance was measured by means of a double barrel microelectrode. Vagal stimulation which caused a 14-20% increase of cycle length diminished electronic potential significantly by a decrease of membrane resistance. The input resistance of the sinoatrial node was not affected. Space constant values calculated by using either a one or a two dimensional model of electrotonic current spread were decreased on average by 13% and 14% respectively. The results from this study show that vagal stimulation which gave rise to a moderate negative chronotropic effect and marked changes in action potential configuration of nodal fibres affects the electrotonic interaction within the sinoatrial node. This may have consequences for the electrical activity and synchronisation of the sinoatrial nodal fibres.


Postischaemic metabolic and functional recovery of rat heart after transient reperfusion with various low Ca2+ concentrations. The effects of transient low Ca2+ reperfusion after ischaemia on metabolic and functional recovery were studied in isolated rat hearts. 31P nuclear magnetic resonance (NMR) was used to monitor creatine phosphate, ATP, intracellular inorganic phosphate (Pi), and intracellular pH during control perfusion (15 min), total ischaemia (30 min), and reperfusion (30 min). During early reperfusion (0-10 min) perfusate [Ca2+] amounted to 1.3 (control group), 0.1, 0.2, 0.3, 0.4, 0.5, 0.6, or 0.7 mmol.litre-1. During late reperfusion (10-30 min) perfusate [Ca2+] was 1.3 mmol.litre-1. Isolated rat hearts were used and perfused according to Langendorff. Recovery of creatine phosphate during early reperfusion was partly abolished during late reperfusion in the 0.1-0.4 mmol.litre-1 groups (p < 0.01). In the 0.1 mmol.litre-1 group creatine phosphate content after 30 min reperfusion was lower (p < 0.05) than in the control group. Recovery of ATP during early reperfusion in the 0.3 mmol.litre-1 group was better than in the control group (p < 0.01). After 30 min reperfusion ATP recovery was better in the 0.3 mmol.litre-1 group (p < 0.01) and worse in the 0.1 mmol.litre-1 group (p = 0.05) than in the control group. Decline of Pi during early reperfusion was more pronounced in the 0.2 and 0.3 mmol.litre-1 groups (p < 0.01) and in the 0.5 and 0.6 mmol.litre-1 groups (p < 0.05) than in the control group. In the 0.3 and 0.4 mmol.litre-1 groups, Pi after 30 min reperfusion was higher (p < 0.05) than after 10 min reperfusion. After 30 min reperfusion left ventricular developed pressure, measured with an intraventricular balloon, was lower in the 0.1 mmol.litre-1 group (p < 0.01) than in the control group. The data show that under the experimental conditions used successive postischaemic reperfusion with 0.1 and 1.3 mmol.litre-1 Ca2+ resulted in poorer metabolic and functional recovery of the hearts than continuous reperfusion with 1.3 mmol.litre-1 Ca2+. Postischaemic reperfusion with 0.1 mmol.litre-1 Ca2+ may predispose the heart to a mild calcium paradox. Successive reperfusion with 0.3 and 1.3 mmol.litre-1 Ca2+ was optimal in terms of ATP recovery but did not result in an increased recovery of left ventricular developed pressure.