Biomedical subjects

G Phillipov

Publications and source records attributed to G Phillipov.

23 records · Page 2Linked to original sources

PubMed1997

Alternate site testing for HbA1c using the Primus CLC330 GHb analyzer.

OBJECTIVE: To determine whether the Primus high-pressure liquid chromatography (HPLC) is suited to alternate site testing (AST) for HbA1c in a hospital diabetes outpatient clinic. RESEARCH DESIGN AND METHODS: Patients were attending the clinic for routine management of their diabetes. A number of diabetic patients with uremia (n = 11) were also investigated. HbA1c levels were measured in the outpatient setting by the Primus HPLC and in a more limited study the DCA-2000 instrument using the new 6-min assay cartridge. HbA1c measurements were also performed with Pierce affinity minicolumns and a Bio-Rad Variant HPLC. RESULTS: The Primus HPLC assay had low imprecision of 2.3, 1.6, and 1.0% for HbA1c levels of 4.7, 7.3, and 11.1%, respectively, and was not prone to interference by carbamylated hemoglobin as found for the ion-exchange Variant HPLC method. Method comparison studies showed that the bias and proportional error between the Pierce affinity minicolumn procedure (standardized with respect to an external quality control program) and the Primus HPLC (Y) was -0.4 and 1.2% respectively (n = 32). Similarly the bias and proportional error between the Primus and DCA-2000 methods was 0.7 and -2.5%. The Primus was shown to give falsely elevated HbA1c concentrations if the time between sequential injections was > 28 min. CONCLUSIONS: The Primus HPLC has a decided advantage over specialty AST instruments, like the DCA-2000, in not only meeting AST requirements but also allowing rapid automated batch processing of all laboratory HbA1c samples.

Chromatography, Affinity↗

PubMed1996

Plasma 1,5-anhydro-D-glucitol concentration and its relation to other plasma components in renal failure and renal transplant recipients.

Plasma levels of 1,5-anhydro-D-glucitol (AG) were measured in non-diabetic patients with renal failure or following renal transplant. For patients with renal failure (n = 20) from various causes, the plasma level of AG was found to be positively associated with urate and negatively with both urea and prior dialysis. The results for seven renal transplant recipients, serially assessed during the post-transplant period, verified an increase in plasma AG with time, approaching normal levels (> or = 70 mumol/l) after 60 days, and which was adversely affected by rejection episodes. The actual mean rate of plasma AG rise ranged from 0.35 to 1.29 mumol/l per day. AG levels for long term (> 1000 days) surviving renal transplant recipients (n = 16) were predominantly related to renal function as assessed by plasma creatinine.

Adult↗

PubMed1996

Apparent cortisone reductase deficiency: a unique form of hypercortisolism.

We describe two female siblings who had production of cortisol (F; as determined from excretion of urinary metabolites) high enough to give rise to Cushing's disease, but who had no clinical indications of the condition. The teenage patients were hirsute as a result of adrenal hyperandrogenism. A notable feature of the condition was the elevated excretion of corticosteroid metabolites with 11-carbonyl groups and very low excretion of 11 beta-hydroxylated steroids. We termed this disorder apparent cortisone (E) reductase disorder. The steroid metabolite phenotype appeared to be the opposite of that seen in the apparent mineralocorticoid excess syndrome, in which the excretion of 11-keto compounds is attenuated. As an example, the tetrahydrocortisol plus 5 alpha-tetrahydrocortisol/tetrahydrocortisone ratio was about 0.04 compared to normal values of about 1.0 and apparent mineralocorticoid excess syndrome values of 5.0-50.0. Paradoxically, among the F metabolites that had not undergone A-ring reduction, 11 beta-hydroxylated steroids dominated over 11-carbonyl compounds. The F/E ratio was about 1.8 compared to an average normal value of 0.54. Neither the father nor the mother of the patient had abnormal F metabolite/E metabolite ratios, although the father did excrete highly elevated free E and F, possibly an unrelated condition. A conclusion was not reached regarding the basis of the disorder. We considered that the most likely causes were 1) defective hepatic 11 beta-hydroxysteroid dehydrogenase-1, 2) failure to develop the adult form of F metabolism, or 3) excessive activity of A ring reduction enzymes acting on E.

11-beta-Hydroxysteroid Dehydrogenases↗

PubMed1996

Short- and long-term reproducibility of the 1-h 50-g glucose challenge test.

A study was undertaken to assess the short-term (intrapregnancy) and long-term (interpregnancy) variability of the 1-h 50-g oral glucose challenge test (GCT). Two groups of pregnant women had GCTs in consecutive pregnancies, 1 (n = 77) and 2 (n = 43) years apart. Their results were compared with published results for a group (n = 53) who had GCTs on consecutive days. Robust estimates of the mean error variance (sigma2 error = sigma2 within-individual + sigma2 analytical) were calculated on log10-transformed data and were for the three groups 0.003995, 0.002603, and 0.0026249 (mg/dL)2, respectively. There was no significant difference between the group variances, establishing that the short- and long-term reliability of the GCT is comparable. Sigma2 between-individuals was estimated from the GCT values for 2695 pregnant women tested during the same period and was the main component (67.1%) of the total sample variation (sigma2 between-individuals / sigma2 population). Estimates of the population mean, sigma2 between-individuals, and sigma2 error were used to compute the probability that an observed GCT value had a true value equal to or greater than the consensus threshold of 7.8 mmol/L (140 mg/dL).

Adult↗

PubMed1995

Screening for diabetic retinopathy.

OBJECTIVES: To identify factors associated with a high risk of diabetic retinopathy in order to rank patients for urgency of examination by fundal photography. DESIGN: Retrospective case survey. PATIENTS: Eight hundred and eighty-eight consecutive diabetic patients who were routinely referred for mydriatic fundal photography to the Queen Elizabeth Hospital, Adelaide, between August 1987 and May 1992. OUTCOME MEASURES: The prevalence of non-proliferative and proliferative diabetic retinopathy and patient biochemical and demographic characteristics and urinary albumin excretion rate. RESULTS: The prevalences of nonproliferative and proliferative diabetic retinopathy were 18.1% and 2.4%, respectively. Multiple logistic regression analysis established that treatment with insulin or oral hypoglycaemic drugs was associated with the highest risk of diabetic retinopathy (odds ratio [OR], 14.7; 95% confidence interval [CI], 3.4-63.2), while duration of diabetes > or = 7 years (OR, 3.6; CI, 1.9-6.8), age 50-66 years (OR, 2.1; 95% CI, 1.1-4.0) and albumin excretion rate > or = 21 micrograms/min (OR, 2.2; 95% CI, 1.1-4.5) were also significant risk factors. Non-significant variables were hypertension, obesity and sex. CONCLUSIONS: Diabetic patients may be ranked for urgency of retinal photographic screening based on mode of treatment and duration of diabetes, thereby facilitating examination of patients at highest risk of asymptomatic diabetic retinopathy and increasing the efficiency of the screening program.

Adult↗