Novel spironucleosides: 1",3"-thiazolidine-2"-spiro-3'-3'-deoxyuridine derivatives

Reaction of 2',5'-di-O-TBDMS-3'-ketouridine 1 with L-cysteine yielded in good yield a resolvable mixture of the two expected epimeric spironucleosides 2 and 3. Amidification of their carboxylic group took place readily and the ribo carboxamide 4 was oxidized to the corresponding sulfoxide 6. Despite their similarity to TSAO derivatives these compounds did not exhibit usable anti-HIV activity.     

Bladder carcinoma with lymphoepithelioma-like differentiation: a report of 9 cases

Both an antibody that catalyzes metal insertion into porphyrins and the corresponding enzyme, ferrochelatase, are shown by resonance Raman spectroscopy to induce distortion in the bound porphyrin substrate. It was found that the enzyme-induced distortion is different from that induced by the antibody; the catalytic antibody produces a distortion which is similar to the one present in the hapten, N-methylmesoporphyrin IX (N-MeMP). Activation of specific out-of-plane vibrational modes reveal that the antibody induces an alternating up-and-down tilting of the pyrrole rings, while ferrochelatase induces tilting of all four pyrrole rings in the same direction (doming). Both distortions are effective in catalyzing metal insertion. The distortion induced in the enzyme is only seen when an inhibitory metal ion is also bound. This observation suggests an allosteric mechanism, in which a conformational change which distorts the porphyrin toward the transition state geometry, is induced by metal binding at an adjacent site. In contrast, the antibody does not have a metal binding site and appears to function largely through binding interactions with the porphyrin.     

The effect of phospholipase C on human blood platelets

The effect of phospholipase C (EC 3.1.4.3) on human blood platelets has been studied. Phospholipase C from Bacillus cereus was purified to homogeneity as judged by analytical and sodium dodecyl sulphate disc gel electrophoresis and by immunoelectrophoresis. Human platelets isolated from platelet-rich plasma by gel filtration or by centrifugation and washing were incubated with phospholipase C. A loss of 20-45% of the total platelet phospholipid was observed, whereas 88% was hydrolyzed when platelet homogenates were submitted to identical enzyme treatment. Intact platelets lost 50-75% phosphatidylethanolamine, 20-50% phosphatidylcholine, and 20-25% phosphatidylserine. Sphingomyelin was not a substrate for the enzyme under the conditions used. The platelets contained no detectable endogenous phospholipase C activity. The loss of phospholipid was not accompanied by aggregation of the platelets, nor did the platelets lose their ability to aggregate with ADP or thrombin. Total platelet factor 3 releasable by freezing and thawing was reduced. Measurements of releasable platelet factor 4 and the efflux of serotonin showed that no release reaction was triggered even when up to 45% of the total phospholipid in the platelets was hydrolyzed. When sphingomyelinase was added together with, before, or after phospholipase C, aggregation occurred. Sphingomyelinase alone gave no aggregation. The gel-filtered platelets also aggregated upon addition of purified phospholipase C from Clostridium perfringens. The distribution of phospholipids in the platelet membrane is discussed.     

The evolution of enzymatic interesterification in the oils and fats industry

Immobilised lipases have now become accepted as a mainstream technology for fat modification. This paper presents the development of this technology in particular for the production of trans‐free fats. One of the factors influencing this development has been concern for health, which has made trans fats a major issue for food manufacturers and consumers. Enzymatic interesterification is a relatively new method for producing trans‐free alternatives for fats used in conventional margarines and shortenings. The development of this technology is examined from the perspective of an eventual industrial application rather than operation only at the laboratory scale. This paper also covers the practical means of operating immobilised enzyme columns and gives examples of how formulations can be adapted to match existing specifications. There are environmental benefits when choosing enzyme technology in comparison with chemical‐based routes. Life cycle assessments have been used to quantify the differences in environmental impact of this new technology. The final process is both capable of providing fats with the correct melting properties but without trans fats and of reducing the environmental impact of fat processing. Finally, the future developments that are anticipated in the applications of this technology are considered.     

The P9 pocket of HLA-DQ2 (non-Aspbeta57) has no particular preference for negatively charged anchor residues found in other type 1 diabetes-predisposing non-Aspbeta57 MHC class II molecules

Susceptibility and resistance to type 1 diabetes are associated with MHC class II alleles that carry non-Asp and Asp at residue 57 of their beta chain respectively. The effect of Asp or non-Aspbeta57 may relate to a differential ability of distinct class II molecules to bind specific immuno-pathogenic peptides. Recent studies in man and mouse have revealed that some type 1 diabetes-predisposing non-Aspbeta57 class II molecules (i.e. DQ8, DR4Dw15 and I-Ag7) preferentially bind peptides with a negatively charged anchor residue at P9. It has been suggested that this is a common feature of type 1 diabetes-predisposing class II molecules. The molecular explanation for such a phenomenon could be that class II beta chains with Aspbeta57 form a salt bridge between Aspbeta57 and a conserved Arg of the a chain, whereas in non-Aspbeta57 molecules the Arg is unopposed and free to interact with negatively charged P9 peptide anchor residues. We have investigated the specificity of the P9 pocket of the type 1 diabetes-associated DQ2 molecule and in particular examined for charge effects at this anchor position. Different approaches were undertaken. We analyzed binding of a high-affinity binding ligand and P9-substituted variants of this peptide, and we analyzed the binding of a set of synthetic random peptide libraries. The binding analyses were performed with wild-type DQ2 and a mutated DQ2 with Ala at beta57 substituted with Asp. Our results indicate that the wild-type DQ2 (non-Aspbeta57) prefers large hydrophobic residues at P9 and that there is no particular preference for binding peptides with negatively charged residues at this position. The specificity of the P9 pocket in the mutated DQ molecule is altered, indicating that the beta57 residue contributes to determining the specificity of the P9 pocket. Our data do not lend support to the hypothesis that all non-Asp beta57 class II molecules predispose to development of disease by binding peptides with negatively charged P9 anchor residues.     

The prognostic value of the QT interval and QT interval dispersion in all-cause and cardiac mortality and morbidity in a population of Danish citizens

AIMS: To evaluate the prognostic value of the QT interval and QT interval dispersion in total and in cardiovascular mortality, as well as in cardiac morbidity, in a general population. METHODS AND RESULTS: The QT interval was measured in all leads from a standard 12-lead ECG in a random sample of 1658 women and 1797 men aged 30-60 years. QT interval dispersion was calculated from the maximal difference between QT intervals in any two leads. All cause mortality over 13 years, and cardiovascular mortality as well as cardiac morbidity over 11 years, were the main outcome parameters. Subjects with a prolonged QT interval (430 ms or more) or prolonged QT interval dispersion (80 ms or more) were at higher risk of cardiovascular death and cardiac morbidity than subjects whose QT interval was less than 360 ms, or whose QT interval dispersion was less than 30 ms. Cardiovascular death relative risk ratios, adjusted for age, gender, myocardial infarct, angina pectoris, diabetes mellitus, arterial hypertension, smoking habits, serum cholesterol level, and heart rate were 2.9 for the QT interval (95% confidence interval 1.1-7.8) and 4.4 for QT interval dispersion (95% confidence interval 1.0-19-1). Fatal and non-fatal cardiac morbidity relative risk ratios were similar, at 2.7 (95% confidence interval 1.4-5.5) for the QT interval and 2.2 (95% confidence interval 1.1-4.0) for QT interval dispersion. CONCLUSION: Prolongation of the QT interval and QT interval dispersion independently affected the prognosis of cardiovascular mortality and cardiac fatal and non-fatal morbidity in a general population over 11 years.     

The ETA receptor antagonist, BMS-182874, reduces acute hypoxic pulmonary hypertension in pigs in vivo

OBJECTIVE: Elevated levels of the potent vasoactive peptide endothelin (ET), have been found in pathophysiological conditions associated with pulmonary hypertension. In this study, we have investigated the effects of the ETA receptor antagonist, BMS-182874, on hypoxic pulmonary hypertension in pigs. METHODS: Pigs were subjected to acute, intermittent 15-min periods of hypoxia (FiO2 0.1). Following a first hypoxia establishing hypoxic baseline values, vehicle or BMS-182874 (10 or 30 mg/kg) was administered i.v. before a second hypoxic period. In separate groups of animals, the effects of the nitric oxide synthase inhibitor N omega-nitro-L-arginine (L-NNA) in combination with BMS-182874 (10 mg) during repeated hypoxia were investigated. The ET-1-blocking properties of BMS-182874 were studied in vivo by infusion of ET-1 during normoxia and in vitro using isolated porcine pulmonary arteries. RESULTS: The hypoxia-evoked increase in mean pulmonary artery pressure was reduced by administration of BMS-182874 (10 mg/kg i.v.; from 42 +/- 8 to 34 +/- 4 mmHg, P < 0.05 and 30 mg/kg i.v.; from 38 +/- 4 to 30 +/- 5 mmHg, P < 0.05). In addition, BMS-182874 at 30 mg/kg reduced the pulmonary vascular resistance during hypoxia (from 7.4 +/- 1.5 to 5.3 +/- 1.1 mmHg.min.l-1 P < 0.05). The hemodynamic response to repeated hypoxia was reproducible in control animals and unaffected by the cyclo-oxygenase inhibitor diclophenac (3 mg/kg). Infusion of L-NNA alone resulted in an augmented pulmonary vasoconstriction during hypoxia; pulmonary arterial pressure from 35 +/- 6 to 43 +/- 9 mmHg; P < 0.05 and vascular resistance from 7.2 +/- 1.1 to 9.9 +/- 1.8 mmHg.min.l-1; P < 0.05. L-NNA in combination with BMS-182874 (10 mg/kg) resulted in a hypoxic pulmonary vasoconstriction of similar magnitude as hypoxic baseline. In addition, BMS-182874 reduced the hemodynamic response to ET-1 in normoxic pigs and competitively antagonized the vasoconstrictor effect of ET-1 in isolated porcine pulmonary arteries. CONCLUSIONS: The non-peptide, selective ETA receptor antagonist, BMS-182874, reduces hypoxic pulmonary vasoconstriction in pigs. The reduction in pulmonary vascular response to hypoxia following BMS-182874 is at least partly independent of nitric oxide.     

Compartment pressure in nailed tibial fractures. A threshold of 30 mmHg for decompression gives 29% fasciotomies

During the past few years we have monitored tissue pressure in patients treated with intramedullary nailing of tibial shaft fractures. A value of 30 mmHg has been used as the threshold for fasciotomy. The purpose of this study was to evaluate this practice. Sixty-three patients were included in the series. Forty-three fractures were closed, 18 grade I (Gustilo) and two grade II. Tissue pressure measurements were performed in 43 patients. Eighteen legs were treated with decompressive fasciotomy, three on clinical findings alone, and 15 after measurement of a pressure higher than 30 mmHg. This gives a fasciotomy rate of 29%. At follow-up two patients were dead. All fractures were healed, and there were no major complications such as deep infection, extensive muscle necrosis, paresis or short-foot syndrome. Three fasciotomized patients had significantly reduced muscle strength compared with the contralateral leg.     

Results of radiotherapy of ureteral obstruction in invasive bladder cancer

Retrospective evaluation of the records of 574 patients with muscle-invasive bladder cancer revealed 90 patients (16%) with ureteric obstruction; the obstruction was bilateral in 24%. The effect of radiotherapy was assessed in 55 patients with 68 obstructed kidneys. Six patients with eight obstructed kidneys required percutaneous nephrostomy or ureteric catheters in addition to radiotherapy. Drainage improved in only 20% of kidneys and the diverting catheter could be withdrawn permanently in only one (17%) of the diverted patients. The median survival was 11 months. Irradiation was followed by significant complications in 37 patients (67%). This raises doubts about the assumed beneficial effect of irradiation on ureteric obstruction due to muscle invasive bladder cancer. The short median survival of 11 months confirms that ureteric obstruction is a poor prognostic factor in muscle invasive bladder cancer.