[Digoxin as a cause of chromatopsia and depression in a patient with heart failure and hyperthyroidism]

67 year old patient with chronic heart failure and persistent atrial fibrillation had overdosed glycosides for several months. The symptoms of gastrointestinal system and nervous system appeared after long term therapy with toxic doses of glycosides. Originally depression was diagnosed based on the central nervous system disturbances. Even though overdose of glycosides was diagnosed the blood serum glycoside level was within the therapeutic limits. Based on the precise analysis of the data, it was concluded that the reason for normal blood serum glycoside level in this case was coexisting hyperthyreosis.

[The role of rheological factors in the pathogenesis of diabetic nephropathy]

In this paper the stages and pathogenesis of diabetic nephropathy have been presented. Factors which influence blood rheology and hemorheologic abnormalities founded in diabetic patients have been reviewed. Attention was paid to the role of rheological parameters in initiating and progression of diabetic nephropathy. The possibilities of prevention of diabetic microvascular complications by influencing blood rheology have been presented.

[Leptin and obesity]

Obesity is associated with increased incidence of cardiovascular diseases, insulin resistance, dyslipoproteinemia and cancer. The discovery of leptin in 1994 has provided a lot of new information about obesity. Leptin is a 167-amino acid peptide synthetized almost exclusively in adipose tissue. This hormone circulates in blood serum in both free and bound forms. The long isoform of leptin receptor is widely distributed in brain, whereas numerous short forms are also being present in peripheral tissues. Leptin acts by binding to the receptors in hypothalamus and altering a release of several neuropeptides, especially neuropeptide Y, regulating energy intake and expenditure. Apart from signaling energy reserves to the brain, leptin promotes hematopoiesis, influences pubertal development and contributes to the increase in arterial blood pressure. Leptin production regulation in humans is poorly understood, but appears to depend on the total body fat, changes in energy intake and serum level of several hormones. Despite the recent advances in the knowledge of both physiology and pathophysiology of leptin, several many important questions require further studies.

[Endothelin and arterial hypertension]

Endothelins (ETs) are peptides of 21 amino acids synthesized and released by variety of cells. Endothelin (now this peptide is called endothelin-1 (ET-1)) was isolated and identified in 1988 by Yanagisawa et al. Following studies revealed two other isoforms of endothelin': Endothelin-2 (ET-2) and endothelin-3 (ET-3). All of them bind to two types of receptors (A and B (ET-A r, ET-Br). ET-A r are responsible for concentration mediating. Two subtypes of ET-B r are known. ET-B1 r mediates vasorelaxation; ET-B2 vasoconstriction. ETs (especially ET-1) have variety of biological actions but the most important are vasoconstrictor and mitogenic action. Through these two mechanism ETs may participate in the pathogenesis and/or in the maintenance of hypertension in both experimental animal models and human essential hypertension. The intravenous infusion of synthetic ET induces a long-lasting elevation of blood pressure in experimental animals and in healthy humans. Number of studies have shown enhanced responses to ET in hypertensive subjects but decreased responses have also been reported. Similarly, plasma levels of ET-1 are either normal or elevated in experimental and human essential hypertension. Numerous investigators have suggested an interaction between ET and angiotensin-converting enzyme inhibitors through the renin-angiotensin system or through the accumulation of endogenous bradykinin. Also calcium antagonists of different classes prevent endothelin-induced contractions. Endothelin- converting enzyme inhibitor (phosphoramidon) and ET-A/B r antagonists (bosentan, BQ-123, FR139317) may have potential role as vasodilators in the treatment of hypertension.

Acetylsalicylic acid (aspirin) test for the diagnosis of renovascular hypertension

OBJECTIVE

To determine whether the administration of acetylsalicylic acid (ASA, also known as Aspirin) differentiates patients with renovascular hypertension from those with essential hypertension, in order to provide a simple alternative to more expensive forms of diagnosis for this condition.

DESIGN

Trial of ASA test in patients with previously diagnosed essential and renovascular hypertension.

SETTING

Inpatient department of an academic health sciences centre in Poznan, Poland.

PATIENTS

Forty patients with essential hypertension and 21 patients with renovascular hypertension.

INTERVENTIONS

Patients were given an intravenous injection of ASA (10 mg/kg body weight), blood pressure was measured and blood was sampled and assayed for plasma renin activity (PRA) before and 30 minutes after the injection.

RESULTS

ASA infusion in patients with renovascular hypertension resulted in a decrease in PRA from 15.2 (standard deviation [SD] 12.4) ng/mL per hour to 7.2 (SD 9.8) ng/mL per hour, whereas in patients with essential hypertension the initial PRA was significantly lower before ASA administration and did not change afterward. In patients with renovascular hypertension, the mean systolic, diastolic and arterial pressure decreased significantly (p < 0.001) after ASA infusion, but these did not change in patients with essential hypertension. Based on the criterion of 4 mm Hg as a detectable decrease in mean blood pressure, the sensitivity of the ASA test was 95.0% and the specificity 82.5%; its positive predictive value was 74% and its negative predictive value 97%.

CONCLUSION

The precise measurement of blood pressure during the ASA test may provide a useful method of differentiating between patients with renovascular and essential hypertension.

[Effect of nifedipine on proximal tubular function in patients with essential hypertension]

The effect of a single 20 mg sublingual dose of nifedipine on function of proximal tubule of nephron in patients with essential hypertension was studied by measuring changes in renal excretion of water, sodium, uric acid and beta-2-microglobulin (B2m) after nifedipine administration. Fifteen patients at the mean age of 40.1 +/- 7 years, with mild to moderate essential hypertension were studied. Systolic (SBP) and diastolic (DBP) blood pressure as well as heart rate (HR) were recorded every hour. Urine was sampled over 60-min, four times. The first two periods were regarded controls and the last two periods followed the administration of a 20 mg sublingual nifedipine dose. Blood samples were taken 1 h before and 1 h after that. Sodium, uric acid, B2m and creatinine in urine and plasma were determined. Nifedipine caused a significant fall in SBP and DBP (p < 0.001) and a marked increase in HR (p < 0.001). Diuresis, sodium (CNa) and uric acid (Cua) clearances were significantly increased (p < 0.001). Similarly, fractional excretion of sodium (FENa) was higher (p < 0.01). B2m excretion (UB2m) showed a two fold increase after nifedipine administration (p < 0.01). A positive correlations were found between the changes in CNa and Cua (r = 0.835, p < 0.001) and between the changes in UB2m and CNa (r = 0.747, p < 0.001). The results indicate that nifedipine induces an increase in diuresis, natriuresis and excretion of uric acid and B2m. These findings and the relationship between the changes in UB2m and Cua proves effect of nifedipine on proximal tubular function.

[Evaluation of uric acid transport in nephrons of patients with calcium nephrolithiasis and hyperuricosuria]

Renal excretion of uric acid was studied in 48 patients with recurrent calcium nephrolithiasis. Hyperuricosuria was found in 16 patients (33%) and among them 10 patients had increased values of urate clearance and fractional excretion. The tubular transport of urate was evaluated by means of pharmacological tests with pyrazinamide (PZA) and benzbromarone (BB) in these 11 patients with hyperuricosuria of renal origin. PZA suppression test was normal in 10 patients while in one case uric acid excretion was not suppressed sufficiently by PZA. Maximal uricorusirc response to BB was increased in two patients, normal in one patient and impaired in eight patients. PZA and BB tests revealed isolated defect of uric acid postsecretory reabsorption in seven patients, impaired reabsorption at both pre- and postsecretory site in one case and enhanced tubular secretion of uric acid in two patients. This study indicates that different defects of uric acid transport in nephron are the frequent cause of hyperuricosuria in patients with recurrent calcium nephrolithiasis.

[Usefulness of determining beta-2-microglobulin in serum and urine in patients with metabolically active kidney calculi and healthy individuals]

The study aimed at evaluating the proximal tubule function in patients with active metabolic urolithiasis with the assay of beta 2-microglobulin in the urine. The studies involved 30 patients with urolithiasis associated with chronic pyelonephritis and 31 patients with urolithiasis without pyelonephritis. Fifty healthy individuals served as a control group. Serum and urine beta 2-microglobulin concentrations were assayed with radioimmunological technique in all persons. Clearance of this microglobulin and tubular reabsorption were calculated. It was found that beta 2-microglobulin excretion with the urine is significantly higher in patients with metabolically active urolithiasis accompanied by the chronic pyelonephritis. beta 2-microglobulin clearance was significantly higher and tubular reabsorption significantly lower than those in patients without pyelonephritis and in control group. These finding suggest a dysfunction of the proximal tubule in patients with urolithiasis produced by the chronic inflammatory process in the urinary system. Negative correlation between blood serum beta 2-microglobulin levels and creatinine clearance was shown. Therefore, serum beta 2-microglobulin concentrations may be of value in evaluation of the glomerular filtration rate.

[Evaluation of selected indicators of the renal proximal tubule function in patients treated with gentamicin]

The study aimed at evaluating proximal renal tubule function in patients with nephrolithiasis and chronic pyelonephritis, and in patients with infectious diseases treated with gentamicin. The study involved 2 groups of patients: group A--17 patients with nephrolithiasis and chronic pyelonephritis and group B--30 patients with other infectious diseases (pneumonia, biliary tract infections) but with normal glomerular filtration rate. Patients from both groups were treated with gentamicin in a daily dose of 2-3 mg/kg for 7-10 days. Serum and urine creatinine levels were assayed in all patients prior to, 2-3, 7, 10 days, and after the treatment. Patients assigned to group B were divided into two subgroups: B1 included 15 patients with normal beta 2-microglobulinuria, and B2 15 patients with increased renal loss of beta 2-microglobulin and decreased tubular reabsorption of this protein. Significant increase in beta 2-microglobulinuria was seen on the third day of therapy, the decrease in the tubular reabsorption and glomerular filtration rate were noted in all patients on the seventh day of gentamicin administration. Beta 2-microglobulinuria was significantly higher in patients from groups A and B2 in comparison with group B1 in which no dysfunction of the proximal renal tubule was present before gentamicin therapy. A degree of beta 2-microglobulinuria is an early and sensitive indicator of gentamicin nephrotoxicity. The risk of nephrotixic symptoms is particularly obvious in patients with deteriorated function of renal proximal tubuli before the treatment with gentamicin.

[Nephrotoxic effect of gentamicin on the function of the proximal tubules of the nephron and glomerular filtration]

The purpose of the study was assessment of gentamicin nephrotoxicity with reference to proximal tubule function and glomerular filtration. The study was carried out in 20 patients with nephrolithiasis and chronic pyelonephritis, and 33 patients with respiratory and bile tract infections treated with gentamicin in doses of 2-3 mg/kg/2 h. In 3 patients with nephrolithiasis and chronic pyelonephritis signs of increased nephrotoxicity of gentamicin (according to Schentag criteria) were found. Similar signs were demonstrated in 3 patients with non-urinary tract infections. The abnormalities included increased excretion of low-molecular protein and beta-2-microglobulin (B2m), reduction of B2m reabsorption and lower glomerular filtration. Beta-2-microglobulinuria increase precede by 4-5 days the fall of the glomerular filtration rate which suggests that beta-2-microglobulinuria assessment is an early sign of gentamicin neurotoxicity.

[Malignant mesothelioma of the pericardium--diagnostic problems]

A case of the malignant mesothelioma of pericardium is presented as this is rare primary neoplasm of pericardium. Diagnosis of the malignant mesothelioma of pericardium is a difficult clinical problem. The authors discuss the value of various diagnostic techniques used in diagnosis of the malignant mesothelioma of pericardium.

[Effect of nifedipine on kidney output of calcium, oxalic acid, and saturation of urinary calcium oxalate]

The study involved 30 patients treated with nifedipine in daily dose of 30 mg for 7 days. Calcium, magnesium, phosphate, oxalate, and uric acid levels in the urine were measured. It was found that nifedipine significantly decreased oxaluria urinary excretion of calcium, magnesium, phosphate, and uric acid remained unchanged following nifedipine therapy. Results may suggest that nifedipine may exert an influence on renal stone formation.

[Effect of intravenous administration of cimetidine on renal excretion of calcium, phosphates, magnesium and adenosine cyclic monophosphate]

An effect of cimetidine on parathyroid glands functioning in healthy subjects was evaluated. Serum calcium, phosphate, and magnesium concentrations together with renal excretion++ of these ions in healthy subjects as well as cAMP excretion++ in selected individuals were determined before and following intravenous administration of cimetidine (Altratmet Lek Ljublijana) in total dose of 500 mg (50 mg injected rapidly as a bolus following with 450 mg in an intravenous infusion during 60 minutes). No significant changes in serum calcium, phosphates, and magnesium concentrations were noted. Renal clearance of calcium and magnesium remained unchanged whereas renal phosphate excretion++ increased from 10.69 +/- 4.9 mL/min to 15.1 +/- 5.41 mL/min (p less than 0.02). Excretion++ of 3.5 cAMP increased from 2.65 +/- 2.19 nM/min to 5.16 +/- 2.0 nM/min (p less than 05). The obtained results do not exclude stimulating effect of intravenous cimetidine on parathyroid glands. Cimetidine given intravenously in the bleeding gastric or duodenal ulcers in the course of the primary hyperparathyroidism+ may decrease serum phosphate levels due to increased exretion of this ion with the urine.