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H Tillil

Publications and source records attributed to H Tillil.

25 records · Page 2Linked to original sources
PubMed1988

Reduction of insulin clearance during hyperglycemic clamp. Dose-response study in normal humans.

Insulin secretion and clearance were studied in eight normal subjects who underwent hyperglycemic clamp studies at plasma glucose levels of 120, 225, and 300 mg/dl on three occasions. Insulin secretion rates were calculated during a 1-h baseline period and during 3 h of glucose clamping from a two-compartmental analysis of peripheral C-peptide concentrations with individual kinetic parameters derived after intravenous bolus injections of biosynthetic human C-peptide. At the 300-mg/dl clamp level, the insulin secretion rate increased to a value 9.9 +/- 0.7 times that of basal at the end of the clamp (mean +/- SE), whereas over the same period, the peripheral insulin concentrations increased to a greater extent, reaching a value 15.4 +/- 1.2 times that of basal (P = .002). This greater relative increase in the insulin concentration in comparison with the corresponding insulin secretion rate suggests a reduction in the clearance of endogenous insulin. A similar trend was seen at the 225-mg/dl clamp level, but the relative increase in the insulin concentration (9.9 +/- 1.5 times that of basal) was not significantly higher than the relative increase in the insulin secretion rate (8.1 +/- 0.5 times that of basal, P = .17). At the 120-mg/dl clamp level, the relative increases in the insulin secretion rate (2.7 +/- 0.2 times that of basal) and the insulin concentration (2.4 +/- 0.2 times that of basal) were similar (P = .26), indicating no reduction in endogenous insulin clearance during moderate stimulation of insulin secretion. In conclusion, a reduction in endogenous insulin clearance occurs during greater stimulation of insulin secretion at higher glucose-clamp levels.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1988

Reevaluation of urine C-peptide as measure of insulin secretion.

Urine C-peptide (UCP) has been proposed as a measure of insulin secretion, because insulin and C-peptide are consecreted in equimolar concentrations by the pancreatic beta-cell. The validity of this approach was tested by comparing insulin secretion rates, calculated by application of a two-compartmental analysis of peripheral C-peptide concentrations, with UCP excretion rates. Insulin secretion and UCP excretion with subjects on a mixed diet were simultaneously measured over a 24-h period in 13 patients with noninsulin-dependent diabetes mellitus and in 14 matched nondiabetic control subjects. The fraction of secreted C-peptide that was excreted in the urine (fractional C-peptide excretion) showed considerable intersubject variability in the diabetic (11.3 +/- 1.6%, range 3.9-20.8) and control (8.0 +/- 1.7%, range 1.1-27.9, P = .07) subjects (means +/- SE). UCP clearance demonstrated a similar degree of variability and was not significantly different (P = .07) between diabetic (23.8 +/- 3.0 ml/min) and control (16.5 +/- 2.7 ml/min) subjects. In control subjects, the 24-h insulin secretion rate correlated more closely with the fasting insulin secretion rate (r = .97, P = .0001), fasting C-peptide (r = .81, P = .0005), and fasting insulin (r = .80, P = .0005) concentrations than with the 24-h UCP excretion rate (r = .62, P = .02). Similar results were obtained in the diabetic patients.(ABSTRACT TRUNCATED AT 250 WORDS)

C-Peptide↗
PubMed1987

Age-corrected empirical genetic risk estimates for first-degree relatives of IDDM patients.

The families of 554 type I (insulin-dependent) diabetics were genetically analyzed according to probands' sex and age at onset applying a modification of Strömgren's method of age correction. Lifetime recurrence risk of type I diabetes (risk up to age 80 yr) for first-degree relatives in three consecutive generations was calculated. The overall risk (+/- 1 SE) for siblings was 6.6 +/- 1.1% and for children was 4.9 +/- 1.7%. The similar risks among siblings and children argue against a simple autosomal recessive trait. The results do not permit a conclusion about a distinct mode of inheritance. Regardless of age at onset, offspring of male probands always had a higher risk than offspring of female probands. Among all probands, fathers were significantly more often affected with type I diabetes (about twice) than mothers (4.1 +/- 0.9 vs. 1.7 +/- 0.6%, respectively). The risk for further siblings of the proband was significantly increased in the presence of a type I diabetic parent (25.2 +/- 10.3 vs. 5.8 +/- 1.0% for remaining probands), indicating a nonrandom clustering type I diabetes in families. Younger age at onset (less than 25 yr) was not associated with an increased risk to siblings. Type II diabetes was not more frequent among parents and siblings of type I diabetics than in the general population. The calculated risk estimates are of practical value in genetic counseling and are important for genetic models concerning type I diabetes.

Adult↗
PubMed1987

Insulin secretion and clearance. Comparison after oral and intravenous glucose.

Insulin secretion and clearance in response to the administration of oral and intravenous glucose was investigated in nine normal men. C-peptide metabolic kinetics were calculated by analysis of individual C-peptide decay curves after the bolus injection of biosynthetic human C-peptide. Glucose was administered to the subjects on three occasions: as a 75-g oral dose, a 75-g i.v. infusion, and an intravenous glucose infusion at a variable rate adjusted to mimic the peripheral glucose levels obtained after the oral glucose load (matching experiment). Glucose, insulin, and C-peptide concentrations were measured for the subsequent 5 h. The glucose level after the oral glucose load (115.9 +/- 2.6 mg/dl, mean +/- SE) closely approximated that after the matching experiment (120.5 +/- 2.5 mg/dl) but was significantly lower than after 75 g i.v. glucose (127.7 +/- 3.4 mg/dl, P less than .05). Analysis of the areas under the peripheral concentration curves (60-360 min) showed that the responses of both insulin (52.7 +/- 5.6 and 46.5 +/- 4.5 pmol.ml-1.300 min-1) and C-peptide (252.7 +/- 27.5 and 267.0 +/- 21.6 pmol.ml-1.300 min-1) were not significantly different after the oral and 75-g i.v. glucose studies, respectively, whereas in the matching experiment, both the insulin (26.1 +/- 3.9 pmol.ml-1.300 min-1) and C-peptide (178.0 +/- 18.9 pmol.ml-1.300 min-1) responses were lower (P less than .05) than in the other two studies. Insulin secretory rates were derived from peripheral C-peptide concentrations with an open two-compartment model and individually derived model parameters. (ABSTRACT TRUNCATED AT 250 WORDS)

Administration, Oral↗
PubMed1984

The predictive factor--a method to simplify Bayes' formula and its application to diagnostic procedures.

According to Bayes' rule the predictive value (PV) of a diagnostic test (= probability of disease if the test is positive) depends on the prevalence of the disease (= a priori probability), the sensitivity (c1) and the specificity (c2) of the test. A new variable has been introduced, the predictive factor (c), which is calculated as follows: c = c1/(c1 +1 -c2). Since the PV only depends on this factor and on the prevalence, the calculation is much easier and a general graphical solution is possible. This simplification renders several additional advantages and facilitates the understanding of the dependence of PV on prevalence.

Bayes Theorem↗
PubMed1980

The chlorpropamide alcohol flush. Lack of specificity for familial non-insulin dependent diabetes.

A facial flush provoked by alcohol in chlorpropamide treated diabetics has been described as a genetic marker for a dominantly inherited type of non-insulin dependent diabetes. In this study a chlorpropamide alcohol flush was observed in 16.9% of control subjects (n = 154), 23.3% of insulin dependent diabetics (n = 437) and 16.5% of patients with non-insulin dependent diabetes (n = 145). Among the non-insulin dependent diabetics no difference in the frequency of the chlorpropamide alcohol flush was found between those with and without a family history of diabetes. Specificity was not improved by skin temperature measurement or additional placebo tests. According to these data the chlorpropamide alcohol flush does not seem to be specific for non-insulin dependent diabetes and hypotheses about the aetiology of this type of diabetes based on the chlorpropamide alcohol flush should be regarded with caution.

Chlorpropamide↗