Catalytic adsorptive stripping voltammetry versus electrothermal atomic absorption spectrometry in the determination of trace cobalt and chromium in human urine.

Two methods of the determination of cobalt and chromium in human urine of non-occupationally exposed populations-highly sensitive catalytic adsorptive stripping voltammetry (CAdSV) and electrothermal atomic absorption spectrometry (ET-AAS)-are evaluated and compared. The CAdSV methods are based on adsorptive accumulation of a cobalt-nioxime (1,2-cyclohexanedione dioxime) or a chromium-DTPA (diethylenetriammine-N,N,N',N'',N''-pentaacetic acid) complexes on a hanging mercury drop electrode, followed by a stripping voltammetric measurement of the catalytic reduction current of the adsorbed complex in the presence of sodium nitrite in case of cobalt or in the presence of sodium nitrate in case of chromium determination. In the CAdSV procedure UV-photolysis was used for the sample pre-treatment; the ET-AAS determination did not require any separate preliminary decomposition of the analyte urine samples. The accuracy of the procedures was checked by the analysis of commercially available quality control urine samples. The detection limits (3sigma) were 0.13mugl(-1) for Co and 0.18mugl(-1) for Cr in ET-AAS determination and 0.007mugl(-1) for Co and 0.002mugl(-1) for Cr in CAdSV measurements. Precision (R.S.D.) was less than 5% for both methods. The study has shown that the CAdSV is a more reliable and sensitive technique for the determination of very low cobalt and chromium contents in urine, the detection of which is not possible when using the AAS technique.

N-acetyl-beta-glucosaminidase and albuminuria in acromegaly.

Significantly increased albuminuria and N-acetyl-beta-glucosaminidase activity in serum and urine have been observed in acromegalic patients in comparison with healthy persons (P less than 0.001). No relationship between these biochemical variables and serum growth hormone or insulin concentration was found in our group of patients. Significant correlation was determined between urinary NAG activity and albuminuria of acromegalic patients (r = 0.84).

Humoral and renal response to acute volume loading in patients with essential hypertension.

The effect of acute volume expansion (2 liters of saline solution in 2 h) on plasma concentrations of atrial natriuretic factor (ANF), plasma aldosterone concentration (PAC), plasma renin activity (PRA) and their relationship to the renal excretion of urine, sodium and potassium were studied in 6 control subjects and 7 patients with essential hypertension (EH) WHO stage I. Saline infusion provoked comparable rise in plasma ANF in both groups (from 2.98 +/- 0.45 to 12.36 +/- 1.74 pmol/l in the control subjects and from 3.80 +/- 0.72 to 15.78 +/- 2.06 pmol/l in EH patients), significant drop in PRA (from 0.915 +/- 0.419 to 0.256 +/- 0.127 nmol/l/h in controls and from 1.711 +/- 0.324 to 0.714 +/- 0.128 nmol/l/h in EH) and in PAC (from 0.30 +/- 0.07 to 0.14 +/- 0.03 nmol/l in control subjects and from 0.53 +/- 0.13 to 0.24 +/- 0.07 nmol/l in EH). The increase of plasma ANF concentrations after volume expansion might be involved in the suppression of PRA and PAC found after this stimulus. Similar increase in plasma ANF after saline infusion in both groups was associated with significantly greater urine and sodium excretion in EH than in controls. From these results it may be suggested that the acute volume expansion during saline infusion evokes a comparable release of ANF into circulation in both EH patients and controls. In EH patients, however, the similar rise in ANF is accompanied by a more pronounced diuretic and natriuretic response. This exaggerated natriuresis after acute volume and sodium loading cannot be explained solely by a rise in ANF.(ABSTRACT TRUNCATED AT 250 WORDS)

[Mutual interaction of the renin-angiotensin system and the atrial natriuretic factor in the renal response to acute volume loading]. / Vzájemná interakce systému renin-angiotensin a atriálního natriuretického faktoru v renální odpovedi na akutní volumovou zátez.

The authors investigated dynamic changes and the interaction of the plasma renin activity (PRA), plasma aldosterone (PAC), i.e. the main representatives of sodium retaining systems, and of the atrial natriuretic factor (ANF) the decisive natriuretic substance in acute expansion of the extracellular volume (ECV) by infusion of two litres of saline in six controls, seven patients with essential hypertension and liver cirrhosis without ascites (6 patients) and with ascites (6 patients). The expansion evoked controversial changes of these systems. It led to a rise of ANF and suppression of PAC and PRA. Although ANF rose after infusion to the roughly similar range (12.4 to 15.7 pmol/l), the natriuretic response to expansion differed significantly in different groups of patients. It was most marked in hypertonic subjects (517.2 to 93.2 mumols/min) and practically zero in ascitic liver cirrhosis (54.2 +/- 44.2 mumols/min). The explanation of this finding may be the persistence of high activity of the renin-angiotensin-aldosterone system despite its partial inhibition by infusion of saline in cirrhosis of the liver (PRA 1.69 +/- 0.66 nmols/l/hr., PAC 1.12 nmol/l). For the renal response to acute expansion of the ECV thus not only the absolute plasma concentration of ANF is decisive but also its ratio to the activity of the sodium retaining renin-angiotensin-aldosterone system.

Glucose metabolism in a patient with insulinoma complicated by hyperosmolar non-ketotic state.

A case of a patient with organic hyperinsulinism complicated by the development of hyperosmolar state is described. The hyperosmolar state was induced by vomiting and dehydration during an acute urinary tract infection. Impairment of glucose metabolism was confirmed by the finding of reduced tissue sensitivity to insulin during a euglycaemic clamp.

[Compensation in diabetes and serum insulin levels in type I diabetics during insulin pump therapy and after changing to treatment with a combination of short- and long-acting insulin]. / Kompenzace cukrovky a hladiny inzulínu v séru u diabetiku I. typu pri lécbe inzulínovou pumpou a po prevedení na lécbu kombinací inzulínu s krátkým a prodlouzeným úcinkem.

Twenty-one type diabetics previously treated in the conventional way with insulin with unsatisfactory results were admitted to hospital. The blood sugar level, serum insulin and non-esterified fatty acids in serum (NEFA) were assessed from 6 a.m. to 2 a.m. during treatment with an insulin pump and after changing the patients to insulins with varying length of action. Patients in the following groups were followed up separately: a) patients with antibodies against insulin treated either by two (n = 4) or three (n = 12) injections; b) patients with antibodies (n = 16) and without antibodies (n = 5), regardless of the number of insulin injections. Changes from the insulin pump regime implied an increased insulin requirement, (significant only in group b) and deteriorated compensation of diabetes which was more markedly manifested when evaluated by index M according to Schlichkrull with the exception of the group without antibodies, where M remained despite the increase in the range of satisfactory compensation. The NEFA profile behaved in a reversed manner, as compared with the serum insulin level. The results confirm the greater success of insulin pump treatment when attempting to maintain the blood sugar level as close as possible to normal values. From the analysis of the blood sugar and serum insulin profile recommendations for the tactics of treatment are derived, when the use of an insulin pump is not possible.

Preferential accumulation of radioactivity in rat kidneys after the administration of 125I-labelled Fab antidigitalis antibodies.

125I-labelled Fab antidigitalis antibodies were administered i.p. to rats, whose organs were removed 20 h later and examined for radioactivity. Maximum radioactivity was found in the thyroid region, followed by the kidneys, liver, adrenals, heart, skeletal muscle and brain. The radioactivity of kidneys was greater than in any of the other organs except the thyroid, where it probably resulted from the uptake of radioiodine, released from the antibodies. After injection of Na125I there was no difference between the kidneys and the liver. In kidney homogenates, radioactivity was present both in the 100,000xg pellet and in the supernatant. The possibility of accumulation or production of the endogenous digitalis-like factor in the kidneys is discussed.

[The Biostator in the diagnosis and therapy of organic hyperinsulinism]. / Biostator v diagnostice a terapii organického hyperinzulinismu.

In 12 patients with the diagnosis of organic hyperinsulinism the authors examined the carbohydrate metabolism on a Biostator, using the method of stabilized glycaemia. They found a highly significantly reduced tissue sensitivity to insulin at the same time a reduced metabolic insulin turnover as compared with healthy subjects (p less than 0.001). Simultaneously they examined the acute action of diazoxide (Proglicem) treatment to which the patients responded in two ways. In one group a decline of the insulin level occurred and the tissue sensitivity to insulin rose, while patients in the second group responded by a rise of serum insulin but there was no response in the insulin sensitivity. In this second group diazoxide treatment obviously does not eliminate hypoglycaemic attacks. Examination on the Biostator thus makes it possible to decide whether conservative treatment is indicated in organic hyperinsulinism.

[Relation between atrial natriuretic factor and the renin-angiotensin-aldosterone system in the renal reaction to acute volume loading in patients with essential hypertension]. / Vztah atriálního natriuretického faktoru a systému renin-angiotensin-aldosteron k renální odpovedi na akutní volumovou zátez u nemocných s esenciální hypertenzí.

Investigation of changes of the atrial natriuretic factor plasma concentration (ANF), plasma renin activity (PRA) and the plasma aldosterone concentration (PAC) and their correlation with the renal excretion of urine, sodium and potassium before and after infusion of 2 1 saline in the course of 2 hours in 6 controls and 7 patients with essential hypertension (EH) revealed the same rise of ANF in plasma of both groups (from 2.98 +/- 0.45 to 12.36 +/- 1.74 pmol/l in controls and from 3.80 +/- 0.72 to 15.78 +/- 2.06 pmol/l in EH), a comparable decline of PRA (from 0.91 +/- 0.419 to 0.256 +/- 0.127 nmol/l/hr in controls and from 1.711 +/- 0.324 to 0.714 +/- 0.185 nmol/l/hr in EH), and PAC (from 0.30 +/- 0.07 to 0.14 +/- 0.03 nmol/l in controls and from 0.53 +/- 0.13 to 0.24 +/- 0.06 nmol/l in EH). The comparable rise of plasma ANF concentration during infusion of saline was associated with a significantly higher renal excretion of urine and sodium in EH, as compared with controls. The authors conclude from these results that the ANF release into the blood stream after an acute volume overload in EH does not differ from controls. Thus the raised natriuresis in EH after a volume overload cannot be explained solely by the rise of ANF. Its renal action depends obviously on the interaction with many other haemodynamic and renal mechanisms, and as regards humoral factors, in particular on the interaction with the renin-angiotensin-aldosterone system. The inhibitory action of elevated ANF concentrations might participate in the suppression of PRA and PAC after a volume overload.

Use of euglycaemic clamping in evaluation of diazoxide treatment of insulinoma.

The use of diazoxide in patients with insulinoma has been evaluated using the euglycaemic clamp technique. There was significantly reduced mean tissue sensitivity to insulin, expressed as the ratio of glucose disposal rate to serum insulin concentration (M/I), in untreated patients compared to the control group. The metabolic clearance rate of insulin (MCRI) was reduced in the patients before treatment in comparison with the controls. The administration of diazoxide (Proglicem1) for three days (3 mg.kg-1 per day) caused a fall in serum insulin concentrations, together with an increase in the metabolic clearance rate of insulin and increased tissue sensitivity to insulin.

Extractive photometric determination of gallium with 8-quinolinol in layered crystals of bismuth telluride-estimation of the determination limit.

A method for determining microgram amounts of gallium in milligram samples of layered monocrystals of the type A(V)(2)B(VI)(3) is described. For the separation of 1-5 mug of gallium(III) from a large excess of bismuth in a single extraction the recommended conditions are pH 3.6-4.2 (acetate buffer, V(aq) 40 ml), an adequate excess of 8-quinolinol for complete extraction and of thiosulphate for masking bismuth. The absorbance of a chloroform extract (V(org) = 10 ml) is measured at 392.5 nm in a 50-mm cell against a blank extract concurrently obtained with a solution of pure Bi(2)Te(3). Reference polycrystalline materials are used to check the precision and accuracy of the method. In routine analysis of layered monocrystals a relative standard deviation of 4-8% is to be expected for about 1 mug of gallium in the extraction system. Estimation of the limit of determination, based on two statistical models, is discussed with respect to the error of the method and the fluctuation of the blank.

Atrial natriuretic peptide concentration and natriuretic hormone activity in plasma of patients with chronic renal failure.

To elucidate further the possible role of atrial natriuretic peptide (ANP) and hypothetical natriuretic hormone (NH) in volume and BP regulation in chronic renal failure (CRF) we measured plasma ANP, digitalis-like substances (DLS) and Na+-K+-ATPase activity (using 86Rb influx into RBC) in 9 patients with CRF before and after hemodialysis. Volume expansion between consecutive dialyses led in all patients to the elevation of plasma ANP (83.4 +/- 14.2 pmol/l) reaching in some overhydrated subjects and/or patients with concomitant cardiac insufficiency concentration greater than 150 pmol/l. Reduced 86Rb influx into RBC before hemodialysis (37.7 +/- 4.9% of controls) was accompanied by higher DLS concentrations (201 +/- 32 pmol/l). Ultrafiltration during hemodialysis with ECFV reduction lowered both ANP and DLS concentrations to 28.1 +/- 9.4 pmol/l and to 151 +/- 23 pmol/l, respectively, and abolished partly the inhibition of Na+-K+-ATPase activity (64.9 +/- 7.6% of controls). These changes corresponded to the degree of ECFV alteration. Our results suggest that both natriuretic principles are activated during ECFV expansion in CRF, probably as a corrective mechanism, with a tendency to normalize when ECFV is reduced during hemodialysis.

Insulin receptors and glucose homeostasis in type 2 diabetics influenced by acetyl-salicylic acid treatment.

The effect of acetyl-salicylic acid administration on insulin receptors on the erythrocytes and the changes of glucose homeostasis examined by hyperglycaemic clamps were evaluated in 8 Type 2 diabetics. Significantly increased number of insulin receptors and decreased insulin affinity constants were found in diabetics after the acetyl-salicylic acid treatment (p less than 0.02). Significantly decreased tissue sensitivity to insulin and metabolic clearance rate of insulin (p less than 0.02) were observed in Type 2 diabetics after the acetyl-salicylic acid treatment. We conclude that acetyl-salicylic acid may impair glucose homeostasis due to interference with insulin action in peripheral tissues.

Radioimmunoassay of atrial natriuretic peptide in human plasma: application to studies of volume and blood pressure homeostasis.

Sensitive radioimmunoassay for determination of immunoreactive atrial natriuretic peptide (ANP) in human plasma was developed and employed for the study of plasma ANP concentrations in healthy controls under basal conditions (2.4 +/- 0.1 pmol/l) and during volume expansion by saline infusion (9.6 +/- 2.0 pmol/l and 14.2 +/- 1.8 pmol/l, respectively). Plasma renin activity and plasma aldosterone concentration exhibited opposite changes during saline infusion. In pathological states associated with extracellular fluid volume (ECFV) expansion, ANP concentration were significantly higher than in the controls (liver cirrhosis 8.6 +/- 0.9; congestive heart failure 33.1 +/- 4.8; chronic renal failure before haemodialysis 72.2 +/- 6.4 pmol/l). Further volume expansion in liver cirrhosis by saline infusion led to the further increase in ANP (13.3 +/- 1.3 and 16.1 +/- 1.5 pmol/l, respectively) and ECFV reduction by ultrafiltration during haemodialysis in chronic renal failure diminished but did not normalize plasma ANP (22.5 +/- 2.9 pmol/l). In patients with arterial hypertension the concentration of ANP exceeded the normal range by 62.5% and reached 8.0 +/- 0.5 pmol/l on the average. Our results support the suggestion that ANP is an important regulatory humoral mechanism participating in the regulation of sodium, volume and blood pressure homeostasis.

Insulin binding to erythrocyte receptors in acromegalic patients in relation to the activity of acromegaly and to concomitant diabetes mellitus.

Insulin binding to receptors on erythrocytes was studied in patients with acromegaly (n = 27) and in control subjects without any endocrine pathology, diabetes or obesity (n = 13). According to fasting serum concentration of growth hormone (GH), acromegalics were divided into two groups: A) GH less than 10 ng/ml (n = 16) and B) GH above 20 ng/ml (n = 11), in which patients were further divided into subgroups with regard to the presence or absence of diabetes. Insulin binding was decreased both in active and inactive acromegalics when compared with controls. A greater decrease was seen in active acromegaly coupled with diabetes. This was not the case of inactive hyperglycaemic acromegalics, where a compensatory increase in the affinity of "empty" receptors might account for a lack of a greater decrease in insulin binding.