Multicentre evaluation of a non-wipe system for the rapid determination of total cholesterol in capillary blood, Accutrend Cholesterol on Accutrend GC.

Accutrend Cholesterol, a non-wipe test for the determination of total cholesterol in capillary blood, was evaluated at four clinical centres. Cholesterol determinations with the Accutrend system using capillary blood were compared with results obtained with the cholesterol oxidase/p-aminophenazone (CHOD-PAP) method using the respective capillary sera. Triacylglycerols, uric acid and haematocrit were determined to evaluate potential interference. Imprecision measurements were performed with venous blood. To examine the reproducibility of results from lot to lot, three different lots of test strips were included in these investigations. Results with Accutrend Cholesterol agree with those of the comparison method within systematic differences of +2.5% to -3.2%, depending on the lot. There was no interference by triacylglycerols up to 10.28 mmol/l (900 mg/dl), by uric acid 60 to 400 mumol/l (1 mg/dl to 7 mg/dl), or by haematocrits between 0.35 and 0.54. Impression data show coefficients of variation of generally less than 5%. Thus Accutrend Cholesterol proved to be a reliable system for the determination of total cholesterol.

[Enzyme immunoassay for the determination of albumin in urine]. / Enzymimmunoassay zur Bestimmung von Albumin im Urin.

Two modifications of a double antibody enzyme immunoassay for the determination of urinary albumin content are described. The method is simple, rapid and precise and can be carried out in test tubes and on microtiter plates as well. In 1:10 diluted urine samples albumin concentrations of 1.25 to 20 mg/l (corresponding to the normal range) can be determined. For a control sample with 0.3 mg/l albumin the intra- and interassay coefficients of variation were 4.9% (n = 11) and 10.4% (n = 21), respectively, on microtiter plates.

Evaluation of metabolic control in type 1 (insulin-dependent) diabetic patients by estimation of serum fructosamine.

The method of Johnson et al. (1982) for the estimation of non-enzymatically glycated serum proteins (fructosamine test) was critically evaluated and modified with respect to photometric readings, incubation conditions, and standardization of the procedure. With this modified method, serum fructosamine concentrations were estimated in type 1 (insulin-dependent) diabetic patients whose glycemic control ranged from strictly to poorly controlled and in normoglycemic healthy control subjects. The mean fructosamine concentrations were for the control group (n = 52) 2.17 mmol/l (range 1.73-2.61 mmol/l) and for the diabetic patients (n = 432) 2.87 +/- 0.60 mmol/l (range 2.27-3.25 mmol/l). There were significant differences in fructosamine concentrations among the diabetic patients, corresponding to the degree of metabolic control. Serum fructosamine levels were closely correlated to the HbA1 levels. Compared with HbA1, fructosamine reflects short-term metabolic changes and appears to be an useful index of short-term glycemia.

[The fructosamine test for the determination of nonenzymatic glycosylated serum proteins. A critical inspection of the method]. / Der Fructosamintest zur Bestimmung nichtenzymatisch glykosylierter Serumproteine. Eine methodenkritische Betrachtung.

A modification of the original method of R.A. Johnson et al. for nonenzymatically glycated serum proteins (fructosamine test) is described. Problems of performance and optimization of the method as well as of calibration and the influence of protein composition on the results are discussed. Measuring is manually performed after a 8 min preincubation interval over a 1 min's period using the spectrophotometer "Spekol 220". Interserial precision was 3.2%. First clinical results demonstrate the possibility to assess glycemic control in type 1 diabetic patients over a integrated time interval.

Importance of cardiovascular autonomic dysfunction in IDDM subjects with diabetic nephropathy.

Diabetic nephropathy (DNP) is associated with increased cardiovascular mortality. This may be contributed to by associated cardiovascular autonomic dysfunction (CAD). The aim of this study was to investigate the prevalence of CAD in patients with insulin-dependent diabetes mellitus (IDDM) at different stages of DNP. We studied patients with incipient DNP (group 1, n = 10), overt DNP (group 2, n = 20), renal insufficiency (group 3, n = 27), and end-stage renal failure (group 4, n = 12) and compared them with 30 IDDM patients without clinical signs of DNP (group 5) and with 17 nondiabetic controls (group 6). All groups were matched for age and diabetic groups were matched for duration of diabetes. Assessments of CAD included beat-to-beat variation during forced respiration, heart-rate response to standing, heart-rate response to Valsalva maneuver, basal heart rate, and blood pressure response to standing. Clinical evaluation included assessment of the history and an examination for peripheral polyneuropathy. We found mean impairment of heart-rate variation during respiration, in response to Valsalva maneuver, and in heart-rate response to standing in all diabetic groups compared with nondiabetic controls (P less than .01). Heart-rate responses differed significantly between patients with renal insufficiency (groups 3 and 4) and with other patient groups (group 5; P less than .01). CAD was shown to be more prevalent in patients with DNP, more so as DNP progresses. To some extent, it is already present in the early stages of DNP. CAD may be a contributory factor for increased cardiovascular mortality in patients with DNP.(ABSTRACT TRUNCATED AT 250 WORDS)

Effects of goldthioglucose on hormone secretion of pancreatic rat islets in vitro.

Goldthioglucose enhanced independently of glucose but related to dose the insulin secretion of pancreatic rat islets in vitro. The stimulatory action is additive to that of glucose, is not inhibited by mannoheptulose and not connected with an altered glucose-utilization. The gold thioglucose-induced insulin secretion is diminished in the presence of epinephrine and Mg++, respectively, and characterized by a uniphasic response peaking at 15 min. In the absence of glucose goldthioglucose did not modify the pancreatic glucagon secretion.

Radioligand assays-methods and applications. IV. Uniform regression of hyperbolic and linear radioimmunoassay calibration curves.

In order to handle all types of radioimmunoassay (RIA) calibration curves obtained in our laboratory in the same way, we tried to find a non-linear expression for their regression which allows calibration curves with different degrees of curvature to be fitted. Considering the two boundary cases of the incubation protocol we derived a hyperbolic inverse regression function: x = a1y + a0 + a-1y-1, where x is the total concentration of antigen, ai are constants, and y is the specifically bound radioactivity. An RIA evaluation procedure based on this function is described providing a fitted inverse RIA calibration curve and some statistical quality parameters. The latter are of an order which is normal for RIA systems. There is an excellent agreement between fitted and experimentally obtained calibration curves having a different degree of curvature.

Apparent discrepancy between the insulin secretory responses in vivo and in vitro in carbohydrate-intolerant Sand rats.

A subpopulation (n = 27) of normoglycaemic Sand rats was characterized as carbohydrate-intolerant by intraperitoneal glucose loading. Five of these animals did not show any rise in peripheral insulin concentrations when injected with glucose. However, when isolated by collagenase digestion their islets still exhibited a significant enhancement of insulin secretion in response to glucose, glyceraldehyde, mannose and theophylline. The in vitro secretory responses were comparable to those of islets from carbohydrate-tolerant Sand rats. The results underline the importance of the natural environment for the B-cell response in vivo.

Abnormal growth hormone response in obesity with normal carbohydrate tolerance and normal thyroid function.

Growth hormone (HGH) response to glucose-induced hyperglycemia and insulin-induced hypoglycemia in 13 obese adults without carbohydrate intolerance and with normal thyroid function were compared with 16 normal weight subjects. HGH levels measured 30 min after placing an indwelling needle in an antecubital vein were significantly lower in obese than in the non-obese controls. HGH concentrations were inversely related to the body weight in all subjects. In the obese group a suppression of serum HGH level was lacking during glucose-induced hyperglycemia and furthermore it was recorded that HGH response to insulin was significantly less as compared with controls. These data indicate that abnormal HGH response is a characteristic in obesity with normal carbohydrate tolerance and normal thyroid function. HGH is a potent physiological stimulatory of lipolysis and it is thus tempting to speculate that an impaired HGH secretion leads to a diminished lipolysis and further deposition of excessive fat in obesity.

Pancreatic and hepatic balances of endogenous insulin and of glucose in the anaesthetized dog during primed and non-primed infusions of glucose and of mannitol.

Simultaneous monitoring of pancreatic and hepatic blood flows and serial analyses of blood glucose and immunoreactive insulin activity in arterial, portal, intestinal and hepatic venous blood were performed in anaesthetized laparotomized dogs. Based on these measurements, the rates of pancreatic insulin secretion, of hepatic insulin uptake and the hepatic glucose balance were computed. Under basal conditions pancreatic output was about 40% of the total hepatic insulin input. 30% of hepatic insulin inflow were actually taken up in the liver. During a primed i.v. glucose infusion (steady blood glucose concentration about 330 mg/100 ml) pancreatic and hepatic blood flows increase rapidly and the insulin secretion exhibits a biphasic pattern. The relative part of hepatic insulin inflow taken up in the liver remained unchanged. A non-primed i.v. glucose infusion provoked a slow increase of blood flow and a rapid but monophasic increase of insulin release. Under these conditions the relative hepatic insulin uptake was transiently increased. During both loads hepatic glucose balance switched from release to uptake. However the non-primed infusion was more effective. When pancreatic and hepatic blood flows were increased without any blood glucose alteration by an infusion of mannitol, insulin secretion did not change; hepatic uptake of insulin decreased, but hepatic glucose output was clearly reduced. A correlation between the rates of insulin secretion, of hepatic insulin inflow and of insulin uptake was observed under all conditions. However, the hepatic glucose balance was correlated to the inflow of insulin or glucose and to the hepatic insulin uptake under certain conditions in individual experiments only.

Insulin secretion reactivation of pancreatic islets from starved rats in vitro.

Starvation of Wistar rats induced a shift of glucose threshold for insulin secretion of isolated islets above 5 mM, which can be restored by pretreatment of the tissue with glucose, mannose, glyceraldehyde, an theophylline, but not with acetylcholine or lactate. The improved insulin secretion is not connected with an enhanced glucose utilization.