D-glucosamine propanedithioacetal, an efficient chiral auxiliary in beta-lactam chemistry.

The synthesis of some monocyclic beta-lactams (monobactams) by the Staudinger reaction using D-glucosamine propanedithioacetal as chiral auxiliary is reported. The influence of several radicals at C3, C4, and C1' (sugar moiety) as well as other structural aspects are considered in relation to the antielastase activity.     

Local movements and population size of European eels,Anguilla anguilla,in a small lake in southwestern Spain

Synopsis Radio telemetry was used to study the movements of European eels,Anguilla anguilla, in a small (1.2 ha) lake in southwestern Spain in March and April, 1985. Observations were taken on the locations of 7 eels at least once each 2 h for a combined total of 1713 h. The size of individual activity regions varied from 2700 to 1300 m². Eels covered a larger area at night than during the day, with an average of 23% and 42% of the activity region used during the day and night respectively. Average distance moved between observations was significantly greater at night than in the day. Eels tracked during rainy and cloudy weather were more active during the day and used a larger total area than did those tracked during drier, more stable weather. The standing crop of eels was estimated to be about 77 kg ha^–1.     

Haemodynamic effects of angiotensin II in conscious, non-ascitic cirrhotic rats

The effect of angiotensin II (AII) on systemic and regional haemodynamics was studied in 18 control and 18 cirrhotic, non-ascitic conscious rats (CCl4/phenobarbital model). Cirrhotic rats were found to retain sodium and to have normal plasma renin and plasma aldosterone concentrations when compared with control animals. Cirrhotic rats showed an enhanced cardiac output (34.4 +/- 0.5 vs. 27.5 +/- 2.0 ml/min in controls) and decreased peripheral resistances (2.96 +/- 0.25 vs. 3.95 +/- 0.31 mm Hg/min/100 g/ml in controls) under basal conditions. When AII was administered cardiac output decreased by 10.7 +/- 1.2% in cirrhotic rats, whereas it increased in control animals (11.2 +/- 2%, p less than 0.005). The AII-induced increase in arterial pressure was lower in cirrhotic than in control rats. The renal blood supply was particularly impaired by AII in cirrhotics, with a maintained flow to other organs (muscle, testes). It is concluded that the response to AII is disturbed in rats with hepatic cirrhosis even in a stage without ascites and with plasma renin and aldosterone concentrations similar to those of control animals.     

Age and growth of yellow eels, Anguilla anguilla, in the estuary of the Guadalquivir river (south-west Spain)

A total of 1068 eels were examined from a population located in the Guadalquivir river estuary (37°N, 6°25'W). Maximum ages recorded were 4 + (males) and 7+ (females), and maximum lengths were 39-1 cm (males) and 54.1 cm (females). No growth was recorded between November and April, most occurring in May and, to a lesser extent, in June-October. Females grew to be larger than males. A classification analysis, based on 17 different European eel populations revealed that populations in brackish waters grew faster than those in fresh waters, but latitude also had an influence. Length-weight relationships obtained for three eel categories (males, females and undifferentiated) were used to estimate relative condition: condition cycles were similar between sexes, with increases in autumn and decreases in winter. There were monthly fluctuations in the sex ratio, and females dominated significantly in the combined catch (234 males/276 females).     

Candida albicans stress mannoproteins expression in superficial and systemic candidiasis

The presence of heat shock mannoproteins (HSMPs) reactive with sIgA was demonstrated in several C. albicans strains. The subculture of the C. albicans isolated from mucosal surfaces on Sabouraud's dextrose agar at 25 °C switched off the HSMP expression. A re-expression of the HSMPs was obtained in the same medium by shifting the temperature of incubation to 37 °C. However, expression of HSMPs in two strains isolated from deep infections was maintained during several subcultures on Sabouraud's dextrose agar at 25 °C. A glycoprotein of 200 kDa seemed to be the main HSMP reacting with vaginal sIgA. The data presented in this study suggest that factors other than temperature can influence the expression of C. albicans HSMPs and therefore these antigens should be referred as stress mannoproteins.Abbreviations HSMPs heat shock mannoproteins - MAb monoclonal antibody - sIgA secretory IgA     

Molecular analysis of a microaerobically induced operon required for hydrogenase synthesis in Rhizobium leguminosarum biovar viciae

The nucleotide sequence (6138 bp) of a microaerobically inducible region (hupV/VI) from the Rhizobium leguminosarum bv. viciae hydrogenase gene cluster has been determined. Six genes, arranged as a single operon, were identified, and designated hypA, B, F, C, D and E based on the sequence similarities of all of them, except hypF, to genes from the hydrogenase pleiotropic operon (hyp) from Escherichia coli. The gene products from hypBFCDE were identified by in vivo expression analysis in E. coli, and their molecular sizes were consistent with those predicted from the nucleotide sequence. Transposon Tn5 insertions into hypB, hypF, hypD and hypE resulted in R. leguminosarum mutants that lacked any hydrogenase activity in symbiosis with peas, but still were able to synthesize the polypeptide for the hydrogenase large subunit. The gene products HypA, HypB, HypF and HypD contained CX₂C motifs characteristic of metal-binding proteins. In addition, HypB bore a long histidine-rich stretch of amino acids near the N-terminus, suggesting a possible role in nickel binding for this protein. The gene product HypF, which was translationally coupled to HypB, presented two cysteine motifs (CX₂CX₈₁CX₂C) with a capacity to form zinc finger-like structures in the N-terminal third of the protein. A role in nickel metabolism in relation to hydrogenase synthesis is postulated for proteins HypB and HypF.     

Effect of propranolol on glycerol induced acute renal failure in rats

The effect produced by propranolol, administered for a prolonged period of time and in large doses, on renal function in rats has been studied, as well as the modifications induced by this treatment in an experimental model of acute renal failure, and the effects of a single dose of propranolol given 1 hour before provoking failure. Propranolol, administered chronically, causes sodium and water retention and increases creatinine clearance. Acute renal failure induced by glycerol in rats treated for 7 days with propranolol is less severe than the one produced in untreated animals. In this ARF model, a single dose of propranolol does not seem to have a protective effect.     

Expression and synthesis of cross-reactive idiotypic antibodies by peripheral blood lymphocytes and their suppression by anti-idiotypes in patients with IgA nephropathy.

We have recently described that patients with IgA nephropathy present high serum levels of anti-BSA idiotypic antibodies that were well correlated with the existence of hematuria. Furthermore, these Id were found in circulating and renal deposited immune complexes. In the present work, we examined the expression of surface idiotypic determinants on PBL by flow cytometry and their in vitro production, using as reagent anti-idiotypic antibodies previously well characterized. The presence of cross-reactive Id-bearing cells was observed in 5 out of 6 patients studied, with frequencies ranging from 3 to 12% of lymphocytes. After 7 days of culture, the spontaneous synthesis of idiotypic antibodies by PBL was found elevated in 6 out of 13 (46%) patients. A major Id cell expression and production was noted in patients with active disease as defined by hematuria. The preincubation of PBL with 20 and 50 micrograms of anti-idiotypic antibodies/2 x 10(6) cells for 3 days induced a significant inhibition of cross-reactive Id production in a dose-dependent fashion, with a degree of suppression between 12 and 50% in five out of six patients studied. In the above assays, as negative controls, we used the anti-Id antibodies previously adsorbed on an Id-Sepharose column. On the whole, these results suggest that patients with IgA nephropathy present dysfunctions in the Id-Anti-Id network that could play an important role in the pathogenesis of this disease.     

Inhibition by L-arginine of the endothelin-mediated increase in cytosolic calcium in human neutrophils

The effect of endothelin (ET) on the cytosolic-free calcium [(Ca2+]i) changes in polymorphonuclear leukocytes (PMN) from normal humans and Wistar rats was investigated. ET induced a dose-related [Ca2+]i peak. This [Ca2+]i transient was blunted by TMB-8 (10(-5)M) and by Ca(2+)-free EGTA medium, therefore suggesting a role of both intracellular Ca2+ release and Ca2+ influx in the generation of the [Ca2+]i peak. Preincubation of PMN with the nitric oxide (NO)-donor L-arginine (L-Arg) markedly blocked the ET-induced [Ca2+]i transient in an enantiomerically-specific manner. A similar blunting effect of L-Arg on the fMLP (10(-7)M)-induced [Ca2+]i transient was detected. The L-Arg antagonist, NG-monomethyl-L-arginine (L-NMMA), reverted the L-Arg blocking effect on both ET- and fMLP-induced [Ca2+]i transients. These data suggest that ET has a potential role in activating Ca2+ mobilization in PMN, an effect that can be inhibited by L-Arg.