Prophylaxis of recurrent urinary tract infection in female patients. Efficacy of low-dose, thrice-weekly therapy with trimethoprim-sulfamethoxazole

Thirty-two women with recurrent urinary tract infections were treated after eradication of existing infections with a mixture of 40 mg of trimethoprim and 200 mg of sulfamethoxazole thrice weekly at bedtime for six months. Six preadolescents received one half this dose. During 21.3 cumulative patient-years of prophylaxis, one infection due to Streptococcus faecalis and one due to a sulfamthoxazole-and trimethoprim-sensitive Escherichia coli occurred--an infection incidence of 0.1 per patient-year. During prophylaxis, 61 of 72 periurethral cultures and 24 of 51 anal canal cultures failed to yield Enterobacteriaceae. One patient had transient colonization with a trimethoprim-resistant E coli during prophylaxis. Twenty-one patients had recurrent infection within six months of discontinuation of prophylaxis, with a mean time to recurrence of 2.6 months. One infection recurred 26 weeks following prophylaxis with a Proteus mirabilis. Thrice-weekly trimethoprim-sulfamethoxazole therapy was effective for prophylaxis of recurrent urinary tract infections and did not predispose to colonization or infection with trimethoprim-resistant Enterobacteriaceae.

Biochemical basis for the enhanced toxicity of deoxyribonucleosides toward malignant human T cell lines

Human malignant T cell lines have high levels of deoxyribonucleoside phosphorylating activity and low levels of deoxyribonucleotide dephosphorylating activity. When incubated with deoxyadenosine or thymidine, the malignant T cell lines rapidly accumulate toxic concentrations of dATP and dTTP, respectively. This unusual pattern of deoxyribonucleotide metabolism renders the malignant T cells especially vulnerable to the toxic effects of deoxyribonucleosides and related analogues.

Regulation of purine de novo synthesis in cultured human fibroblasts: the role of P-ribose-PP

Procedures for assaying the rate of purine de novo synthesis in cultured fibroblast cells have been compared. These were (i) the incorporation of [(14)C]-glycine or [(14)C]formate in alpha-N-formylglycinamide ribonucleotide (an intermediate in the purine synthetic pathway) and (ii) the incorporation of [(14)C]-formate into newly synthesised cellular purines and purines excreted by the cell into the medium. Fibroblast cells, derived from patients with a deficiency of hypoxanthine phosphoribosyltransferase (HPRT-) (EC 2.4.2.8) and increased rates of purine de novo synthesis, were compared with fibroblasts from healthy subjects (HPRT+). Fetal calf serum, which was used to supplement the assay and cell growth medium, was found to contain sufficient quantities of the purine base hypoxanthine to inhibit purine de novo synthesis in HPRT+ cells. This inhibition was the basis of differentiation between HPRT- and HPRT+ cells. In the absence of added purine base, both cell types had similar capacities for purine de novo synthesis. This result contrasts with the increased rates of purine de novo synthesis reported for a number of human HPRT- cells in culture but conforms recent studies made on human HPRT- lymphoblast cells. The intracellular concentration and utilisation of 5-phosphoribosyl-1-pyrophosphate (P-Rib-PP), a substrate and potential controlling factor for purine de novo synthesis, were determined in HPRT- and HPRT+ cells. The rate of utilisation of P-Rib-PP in the salvage of free purine bases was far greater than that in purine de novo synthesis. Although HPRT- cells had a 3-fold increase in P-Rib-PP content, the rate of P-Rib-PP generation was similar to HPRT+ cells. Thus, in fibroblasts, the concentration of P-Rib-PP appears to be critical in the control of de novo purine synthesis and its preferential utilisation in the HPRT reaction limits its availability for purine de novo synthesis. In vivo, HPRT+ cells, in contrast to HPRT- cells, may be operating purine de novo synthesis at a reduced rate because of their ability to reutilise hypoxanthine.

Clinical efficacy and toxicity of netilmicin in the treatment of gram-negative infections

Netilmicin, a new semisynthetic aminoglycoside antibiotic, was used to treat 41 infections in 38 patients. The outcome of four infections could not be evaluated: two patients received inadequate therapy and two did not have gram-negative infections. Clinical improvement occurred in 36 (97%) of the 37 gram-negative infections, and bacteriologic cure occurred in 30 (86%) of the 35 evaluable infections. Therapeutic serum concentrations of netilmicin were readily achieved by both intramuscular and intravenous routes. Reversible ototoxic effects occurred in 1 (3%) of 35 courses of therapy evaluated, reversible nephrotoxic effects occurred in 5 (14%) of 36 courses and mild reversible alterations in liver function occurred in 3 (19%) of 34 courses. Netilmicin appears to be effective and safe in the treatment of aerobic gram-negative infections.

Uricosuric response to increasing doses of the indanone diuretic MK-196 in healthy volunteers

Doses of 20, 40, 60 and 80 mg of the indanone diuretic MK-196 and 40 mg of frusemide were administered in random order to 5 healthy volunteers in a stable metabolic state, on the same day for 5 consecutive weeks. Diuresis, natriuresis and kaluresis increased with increasing doses, the natriuresis lasting for about 12 h and the kaluresis for about 24 h. Uricosuria increased with increasing doses of MK-196 and lasted for about 6 h. The uricosuria was followed by urate retention, so that there was little net change in the renal excretion of urate. Significant weight loss occurred, so that there was probably some associated plasma volume contraction, which would promote urate retention. By contrast, frusemide caused a reduction in renal excretion of urate at all times.

Altered leucyl-transfer RNA synthetase from a mammalian cell culture mutant

Altered leucyl-tRNA synthetase from a mammalian cell culture temperature-sensitive mutant, tsHl, was compared with enzyme from normal wild type Chinese hamster ovary cells. The mutant enzyme had a Km for leucine four times larger than that of wild type and enzyme levels 3-10% that of wild type. The presence of tRNA was necessary during in vitro heating of the mutant enzyme to allow expression of thermolability while the presence of tRNA protected wild type enzyme against thermal inactivation. The tsHl enzyme was stable when heated alone or in the presence of tRNA, leucine, and ATP simultaneously. The mutant's enzymes aminoacylated tRNALeu, tRNAVal, and tRNAIle with fidelity in vitro as determined by cochromatography of the amino-acyl-tRNA isoacceptors on RPC-5 reversed phase chromatography. The mutant failed to show any defect other than the direct formation of leucyl tRNALeu by leucyl-tRNA synthetase.

Psychiatric morbidity in general practice and the community

The "General Health Questionnaire" was used to assess the psychiatric morbidity among 365 consecutive attenders at a general practice and to compare this with a systematic random sample of 213 patients drawn from the lists of the same practice. Those attending a general practitioner are shown to be more psychiatrically disturbed than a random sample of the practice population, and this difference remains when those attending for psychological symptoms are discounted. Various social and demographic characteristics which distinguish between those who do and those who do not attend a doctor with a given set of psychological symptoms are described.

Drug usage review and inventory analysis in promoting rational parenteral cephalosporin therapy

Drug usage review and inventory analysis data on the cephalosporin antibotics were presented by the pharmacy to a hospital pharmacy and therapeutics committee in an effort to promote rational use of these drugs and decrease drug costs. The committee recommended that cefazolin be the parenteral cephalosporin of choice. Cephalothin was placed on a limited formulary status for ophthamology patients and patients with renal impairment. Efforts by the committee to promote physician compliance with its recommendations are discussed.

Adenine phosphoribosyltransferase deficiency: its inheritance and occurrence in a female with gout and renal disease

A deficiency of adenine phosphoribosyltransferase (APRT) enzyme activity to approximately 40% of normal has been found in erythrocytes from a young woman aged 24 years, who had suffered from recurrent gouty arthritis since 11 years of age. She also demonstrated considerable, although asymptomatic, renal impairment with a creatinine clearance of one-third normal. Her father had suffered from gouty arthritis but had a normal APRT activity; he was obese, had a high purine intake and was a regular beer drinker. The patient's mother was asymptomatic with a normal serum urate concentration, but demonstrated a similar reduction in APRT activity to that of her daughter. Eleven other asymptomatic members of the family also demonstrated a similar reduction in APRT activity in erythrocyte lysates. The pattern of inheritance was consistent with autosomal transmission. Concentrations of phosphoribosylpyrophospate (PRPP) in erythrocytes were within normal limits both in the subjects with deficient, and in those with normal, APRT activity. Partial purification of APRT enzyme from erythrocytes of the index case did not reveal any difference from the normal enzyme as far as Michaelis constants, heat stability, or mobility in polyacrylamide gel was concerned. No primary abnormality of lipoprotein metabolism was demonstrated either in the propositus or in other members of her family. Study of urate metabolism in the propositus indicated that, although urate production was within the normal range in absolute terms, there was increased incorporation of glycine into produced urate, usually taken as one index of de novo urate production. Impaired renal excretion of urate was also shown. Although detailed study of urate metabolism has not been undertaken in other family members with APRT deficiency, no conclusive relationship has yet been demonstrated between APRT deficiency and disordered urate metabolism.