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Biomedical subjects

F Nye

Publications and source records attributed to F Nye.

10 recordsLinked to original sources

'Disappearing diabetes'--resolution of apparent Type 1 diabetes in a patient with AIDS and cytomegalovirus (CMV) infection.

A 30-year-old African female with established acquired immunodeficiency syndrome (AIDS) and no history of diabetes, presented in severe diabetic ketoacidosis (DKA). Blood pH was 6.96, serum bicarbonate 5 mmol/l, plasma glucose (PG) 33.0 mmol/l, and urine heavily positive for ketones. She responded to standard treatment and was established on twice-daily subcutaneous insulin. Four months later her insulin was stopped because of hypoglycaemic attacks on small doses. A glucose tolerance test (GTT) at 6 months postdiagnosis was normal (fasting PG 4.4 mmol/l and 2 h PG 7.5 mmol/l), and at 12 months random PG was 4.1 mmol/l and HbA1c 4.3%. The onset of her apparent Type 1 diabetes coincided with an HIV-associated cytomegalovirus (CMV) infection, and a reversible 'CMV insulitis' may be an explanation. Alternatively, the patient may have had what has recently been described as 'atypical diabetes' in African or Afro-Caribbean diabetic patients. Here resolution of diabetes may occur after presentation, though complete return to normoglycaemia after true DKA is very unusual.

AIDS-Related Opportunistic Infections↗

From trench fever to endocarditis.

The case of a 44 year old woman with infective endocarditis due to Bartonella quintana, an organism long recognised to cause a condition known as trench fever, is reported. This case illustrates the lengthy differential diagnosis of "culture negative" endocarditis. In addition the presence of serological cross reactivity of Bartonella spp and Chlamydia spp demonstrates the potential for misdiagnosis in these circumstances.

Adult↗

Zidovudine phosphorylation in HIV-infected patients and seronegative volunteers.

OBJECTIVES AND DESIGN: Measurement of phosphorylated zidovudine (ZDV) inside infected cells is more likely to provide satisfactory dose response relationships than serum concentrations. This study provides information on ZDV phosphorylation in HIV-seronegative volunteers (n = 5) and in patients with HIV infection (n = 12). METHODS: Intracellular ZDV phosphate metabolites were measured in peripheral blood mononuclear cells isolated from whole blood by density cushion centrifugation. Cells were washed and extracted overnight with 60% methanol prior to analysis by high performance liquid chromatography. Fractions eluted from the column corresponding to ZDV, ZDV monophosphate (ZDV-MP), ZDV diphosphate (ZDV-DP) and ZDV triphosphate (ZDV-TP) were collected, hydrolysed by acid phosphatase and ZDV levels quantified by radioimmunoassay. RESULTS: The area under the plasma ZDV concentration-time curve (AUC0-6 h) was similar in seronegative volunteers and patients [mean +/- SD, 4.64 +/- 2.50 versus 5.56 +/- 2.67 mumoles/l h; 95% confidence interval (CI), -4.39-2.23; P = 0.646, Mann-Whitney U test]. However, ZDV phosphorylation was greater in patients, with the AUC0-6 h for total phosphate metabolites being 5.91 +/- 3.42 pmoles/10(6) cells h compared with seronegative volunteers (0.66 +/- 0.48 pmoles/10(6) cells h; 95% CI, -8.35 to -2.32; P = 0.0003). The concentration of ZDV-TP was similar in both groups, the increase in total phosphates in patients being due primarily to ZDV-MP. ZDV-MP AUC0-6 h and total ZDV phosphate AUC0-6 h were closely correlated (r2 = 0.94). The relationship between total ZDV phosphate AUC0-6 h and the CD4 count demonstrates that patients with a count < 100 x 10(6)/l have much higher ZDV phosphate levels, predominantly ZDV-MP. CONCLUSION: ZDV is phosphorylated to a greater extent in patients than in healthy volunteers. The increased ZDV-MP in patients with low CD4 counts may explain the well known occurrence of increased ZDV toxicity in patients with more advanced disease. The ability to measure ZDV phosphorylated metabolites (without the administration of radiolabelled nucleoside) represents a significant advance in our understanding of the clinical pharmacology of the drug.

Acquired Immunodeficiency Syndrome↗

Zidovudine pharmacokinetics in zidovudine-induced bone marrow toxicity.

1. The major adverse effect of zidovudine (ZDV) is haematological toxicity which results in anaemia and granulocytopenia. The aim of the present study was to investigate if HIV-positive patients developing erythroid aplasia/hypoplasia are exposed to higher plasma concentrations of ZDV owing to impaired hepatic metabolism to the major metabolite, 3'-azido-3'-deoxy-5'-beta-D-glucopyranuronosylthymidine (GZDV). 2. Twelve HIV-positive male patients were studied, six having developed bone marrow aplasia/hypoplasia within the first 6 months of ZDV therapy. Each of the patients exhibiting toxicity were matched for age, weight, risk factors for HIV infection and disease stage with patients who had no evidence of early bone marrow toxicity. 3. ZDV was administered orally in doses of 3-10 mg kg-1 and blood samples taken at intervals to 6 h. Urine was collected over the whole 6 h period. ZDV and GZDV were assayed by h.p.l.c. 4. There were no significant differences in the pharmacokinetic parameters between the two groups of patients. For patients with early bone marrow toxicity the elimination half-life of ZDV was 1.10 +/- 0.16 h with an oral clearance of 2752 +/- 1031 ml min-1 compared with values of 1.06 +/- 0.18 h and 2843 +/- 730 ml min-1 seen in the control group. Similarly there was no significant difference in the pharmacokinetics of GZDV or the urinary ratio of GZDV to ZDV. 5. Therefore, despite the fact that ZDV toxicity to haematopoietic progenitor cells has been previously shown to be dose related, there was no indication from this study that it is directly related to plasma concentrations of ZDV.

Administration, Oral↗

Pharmacokinetics of zidovudine and dideoxyinosine alone and in combination in patients with the acquired immunodeficiency syndrome.

1. Zidovudine (ZDV) has proved unsuccessful in controlling disease progression over extended periods of time in patients with AIDS. Combination of ZDV with another reverse transcriptase inhibitor, dideoxyinosine (ddI) may improve the duration of effectiveness of antiretroviral therapy. The aim of this study was to investigate the possibility of a pharmacokinetic drug interaction between ZDV and ddI. 2. The pharmacokinetics of ZDV and ddI were determined in eight patients with AIDS who were randomised to receive ZDV 250 mg orally, ddI 250 mg orally or a combination of ZDV 250 mg plus ddI 250 mg orally on 3 study days separated by 1 week. 3. The administration of ZDV did not significantly alter ddI pharmacokinetics. The mean AUC was 6.8 +/- 2.0 s.d. and 7.6 +/- 2.5 s.d. mumol l-1 h and oral clearance was 2766 +/- 686 and 2660 +/- 1297 ml min-1 in the presence and absence of ZDV, respectively. 4. In the presence of ddI the elimination half-life of ZDV was increased significantly by 18% from 1.1 +/- 0.3 to 1.3 +/- 0.3 h (P < 0.05) and the mean AUC increased significantly by 35% from 4.8 +/- 1.5 to 6.5 +/- 1.5 mumol l-1 h (P < 0.05). The clearance was decreased by 29% from 3518 +/- 1123 to 2505 +/- 575 ml min-1, but this difference was not significant. The renal clearance of ZDV was not altered by ddI. 5. Administration of ddI also resulted in a significant 22% increase in the AUC of GZDV, from 28.5 +/- 15.7 to 34.9 +/- 12.8 mumol l-1 h (P < 0.05).(ABSTRACT TRUNCATED AT 250 WORDS)

Acquired Immunodeficiency Syndrome↗

Infective endocarditis caused by Streptococcus mutans.

Members of the viridans group of streptococci are the commonest causes of bacterial endocarditis. However, Streptococcus mutans, a member of this group associated with dental caries which might be expected to be commonly associated with endocarditis, has only rarely been reported. This is possibly because of difficulties in isolation and identification. Differing blood culture media may affect the chances of isolation of these organisms, and, though brain-heart infusion, thiol, tryptic soy, and glucose-brain infusion broths have all proved satisfactory, subcultures may require increased CO2 concentrations for growth. Plemorphism in the resultant colonies and in the individual organisms may give rise to a hazardous misinterpretation of this appearance as contamination. Strep. mutans and the similarly penicillin sensitive Strep. bovis may be differentiated from the penicillin resistant enterococci by their lincomycin sensitivity and intolerance of 6-3 per cent sodium chloride. Precise differentiation of streptococci in bacterial endocarditis is of value both epidemiologically and in the management of the disease.

Adult↗