5'-Untranslated sequences of two structural genes in the qa gene cluster of Neurospora crassa

The coding regions of two genes (qa-2 and qa-3) in the qa gene cluster of Neurospora crassa have been localized by nucleotide sequence analysis combined with data on previously determined NH2-terminal amino acid sequences for the proteins that these genes encode. The start point of transcription for each of these genes has been determined by nuclease S1 mapping experiments with poly(A)+RNA isolated from quinic acid-induced cultures of N. crassa. The sequences of approximately 200 nucleotides 5' to the start point of transcription have been compared with each other and with those of other eukaryotes. The results show that neither of these regions for the qa-2 nor the qa-3 genes share any significant homology with sequences apparently conserved in higher eukaryotic promoters (-25 and -70 regions). However, the qa-2 and qa-3 sequences do show homology with each other in these regions. Comparison of the 5'-flanking regions of these Neurospora genes with those of several Saccharomyces cerevisiae genes reveals a number of similarities in the region preceding the translation initiation codons.

Lymphocyte studies in rheumatoid arthritis. V. Suppressor cell function in peripheral blood

Peripheral blood lymphocytes from 30 patients with rheumatoid arthritis and 14 controls were examined for suppressor activity by two different assays. These were the Concanavalin-A-induced and the short-lived suppressor cell assays. There was no difference in suppressor activity between patients and controls, the suppressor activity of HLA-DR3 positive patients was no less than that of non-DR3 patients. However, patients with nodules showed reduced suppression in the short-lived suppressor cell assay when compared with patients without nodules.

Gastric infarction: a complication of selective vasopressin infusion

This report describes a case of massive gastric hemorrhage, initially controlled by selective arterial vasopressin infusion. Infusion was followed by extensive necrosis of the gastric wall which necessitated subtotal gastrectomy. Gastric necrosis following arterial infusion is rare and in this case appears to be due to migration of the infusion catheter into a peripheral branch of the left gastric artery in a patient whose gastric circulation had been compromised by prior surgery. The complications related to the use of arterial infusion for the control of gastric hemorrhage are discussed and the literature is reviewed.

Crown ether catalysis of decarboxylation: a general survey of reactivity and detailed analysis of the triphenylacetate anion

The effect of 18-crown-6 ether 3 on the decarboxylation rate in THF of sodium salts of carboxylic acids formally derived from hydrocarbons has been investigated and these acids include 9-phenylfluorene-9-carboxylic acid, fluorene-9-carboxylic acid, phenylacetylene carboxylic acid, triphenylacetic acid, and diphenylacetic acid. Addition of equimolar 3 resulted in an increase in decarboxylation rate of 13- to 500-fold and there was a correlation between the decarboxylation rate and the pKa value of the product hydrocarbon.The decarboxylation of triphenylacetate was investigated in detail. The effect on reaction rate of cation (Li+, Na+, K+), crown ether concentration, water concentration, and solvent polarity has provided information as to optimum reaction conditions and has helped to clarify the reaction mechanism.

Nephrotoxicity of cephalosporin-gentamicin combinations in rats

TO STUDY THE POSSIBILITY THAT CEPHALOSPORINS AUGMENT THE NEPHROTOXICITY OF GENTAMICIN, GROUPS OF RATS WERE GIVEN FOUR HOURLY SUBCUTANEOUS DOSES OF: gentamicin (5 mg/kg), gentamicin plus cephalothin (100 mg/kg), gentamicin plus cefazolin (20 mg/kg), gentamicin plus cefazolin (50 mg/kg), gentamicin plus cephaloridine (50 mg/kg), or saline diluent for 15 days. Periodic measurements were made of urine volume, urine osmolality, urine protein excretion and lysosomal enzymuria, as well as blood urea nitrogen, creatinine clearance, and drug concentrations in renal cortex and medulla. Tissue was examined by light and electron microscopy. Enzymuria and proteinuria increased early in the course of all treatment groups, whereas urine osmolality declined. No distinct patterns of these variables were discernable among the groups. Gentamicin alone, gentamicin plus cephalothin, and gentamicin plus cefazolin (20 mg/kg) caused the same significant fall in glomerular filtrate rate from control values by day 15 (P < 0.05). Gentamicin plus cefazolin (50 mg/kg) and gentamicin plus cephaloridine failed to cause a decline in glomerular filtration rate compared with controls (P > 0.05). Gentamicin concentrations in renal cortex were 5 to 10 times higher than those in medulla in all groups. Cephaloridine and cefazolin (50 mg/kg) also displayed a gradient pattern in renal cortex, whereas cephalothin and cefazolin (20 mg/kg) did not. Cytosegrosomes with myeloid figures were characteristic ultra-structural changes seen in all groups; however, they tended to be smaller with less numerous myeloid bodies in the groups receiving gentamicin plus cephalothin, cefazolin (50 mg/kg), or cephaloridine. Cephalosporins did not augment gentamicin toxicity. High doses of cefazolin and cephaloridine protected kidneys from gentamicin nephrotoxicity. The protection may involve intracellular drug interaction within the renal cortex.

Experimental aminoglycoside nephrotoxicity

The nephrotoxicities of gentamicin and three other experimental aminoglycosides were compared at a single 60 mg. per kilogram per day dose in rats. Renal function, lysosomal enzymuria, and antibiotic concentrations in plasma, urine, and renal tissue were measured at regular intervals throughout the course of treatment. Kidney tissue was examined by light and electron microscopy in animals killed at intervals throughout the period of antibiotic administration. Proteinuria and enzymuria were early indicators of nephron dysfunction, whereas endogenous creatinine clearance declined later in the course of treatment. All animals were killed 24 hours after a previous antibiotic injection and displayed sustained renal tissue antibiotic concentrations which were 5 to 10 times higher than those in serum or urine. When assayed separately, renal cortical tissue had a fivefold greater antibiotic concentration than renal medulla. Light microscopy displayed necrosis of the pars convoluta of the proximal tubule. Electron microscopy revealed appearance of cytosegrosomes with myeloid bodies. It is possible that impaired cytoplasmic degradation of sequestered organelle membranes, resulting from aminoglycoside accumulation, is responsible for the myeloid body formation and subsequent tubular necrosis.

Enzymuria in gentamicin-induced kidney damage

To assess their potential value as early indicators of gentamicin-induced kidney damage, lysosomal hydrolases were measured in the 24-h urines of rats receiving 30 or 60 mg of gentamicin per kg per day for 15 days. Proteinuria, urine osmolality, blood urea nitrogen, and creatinine clearance were also measured. Kidney tissue was examined by both light and electron microscopy. Beta-galactosidase, beta-n-acetyl-hexosaminidase, and alpha-fucosidase were sensitive indicators and were significantly elevated above control values by day 3 at both doses (P < 0.01). Proteinuria, urine osmolality, and tests reflecting glomerular filtration rate were later indicators of nephron damage. Changes by light microscopy were detected on day 5. Necrosis was most prominent in the proximal convoluted tubules on day 10. Electron microscopy revealed numerous cytosomes with myeloid bodies within the proximal tubular epithelium on day 5. Lysosomal enzymuria appears to be an early manifestation of gentamicin nephrotoxicity and may possibly be related to the lysosomal abnormalities seen on electron microscopy.