The biosynthesis of the glycopeptide antibiotic teicoplanin was studied by growing a teicoplanin producing strain of Actinoplanes teichomyceticus (ATCC 31121) on glucose containing either 34.0% ...1-(13)Cglucose or 9.7% U-(13)Cglucose. The fractional enrichment pattern of teicoplanin produced in the medium containing 1-(13)Cglucose was obtained from a one-dimensional (13)C spectrum. The enrichment pattern showed characteristic peaks indicating that amino acids 3 and 7 are derived from acetate, whereas amino acids 1, 2, 4, 5, and 6 are derived from tyrosine. Multiplet structures in heteronuclear single quantum coherence spectra of teicoplanin produced in the medium containing U-(13)Cglucose showed characteristic coupling patterns supporting these results. Fractional enrichment patterns and multiplet structures of the three sugars in teicoplanin showed that about 50% of the sugars have the same labeling pattern as the glucose substrate whereas the rest have a labeling pattern showing that they are reassembled, probably from precursors in the primary metabolism.
Objective
The aim of the present study was to develop a rat model for in vivo studies of the local effects of the renin-angiotensin system (RAS) following elimination of circulating renin.
Methods
...Sprague Dawley rats were bilaterally nephrectomised and had a peritoneal dialysis catheter implanted. The rats were maintained on dialysis continuously for 48 hours, using Dianeal PD4 3.86% glucose dialysis solution. The peritoneal catheter and an automated system for dialysate exchange were made in our laboratory. A sham nephrectomised control group of rats was also dialysed.
Results
Nephrectomised and sham-operated rats remained active and in good general condition during peritoneal dialysis. At 48 hours, in nephrectomised, dialysed rats, peritoneal urea clearance was 4.14±0.52 ml/hour, plasma urea was 40.0±7.7 mmol/L, plasma creatinine was 0.423±0.070 mmol/L and plasma renin was below the limit of detection.
Conclusions
In conclusion, it was possible to sustain bilaterally-nephrectomised rats on continuous peritoneal dialysis for 48 hours, pending elimination of renin from the circulation. The nephrectomised dialysed rat model should be useful for investigation of the physiological effects of the circulating versus the local RAS.
A pulse radiolysis technique was used to study the UV absorption spectrum of CF3CF2CF2O2 radicals, at 230 nm σ = (3.2 ± 0.4) × 10-18 cm2 molecule-1. Rate constants for reactions of CF3CF2CF2O2 ...radicals with NO and NO2 were k 3 > 7 × 10-12 cm3 molecule-1 s-1 and k 4 = (7.6 ± 2.4) × 10-12 cm3 molecule-1 s-1, respectively. The rate constant for reaction of F atoms with CF3CF2CF2H was determined by using an absolute rate technique to be (3.6 ± 1.3) × 10-13 cm3 molecule-1 s-1. The atmospheric fate of CF3CF2CF2O radicals is decomposition via C−C bond scission to give CF3CF2 radicals and CF2O. In one bar of SF6 at 296 K, CF3CF2CF2O radicals decompose with a rate > 1.5 × 105 s-1. In their turn CF3CF2 radicals are converted into CF3CF2O radicals which also decompose via C−C bond scission. As part of this work a relative rate method was used to measure k(Cl + CF3CF2CF2H) = (3.4 ± 0.7) × 10-16 and k(F + CF3CF2CF2H) = (3.2 ± 0.8) × 10-13 cm3 molecule-1 s-1. The results are discussed with respect to the atmospheric chemistry of HFC-227ca.
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