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Biomedical subjects

S Abdelhamid

Publications and source records attributed to S Abdelhamid.

At least 37 records · Page 2Linked to original sources
PubMed1987

21-Deoxyaldosterone excretion in patients with primary aldosteronism and 21-hydroxylase deficiency.

21-Deoxyaldosterone appears in urine in free and conjugated forms. Total excretion is best determined after acid hydrolysis (pH 1) of urine, followed by extraction, repeated chromatographic purification, and quantitation of the steroid by RIA. 21-Deoxyaldosterone excretion was normal in 70% of patients with essential hypertension (n = 18), while 30% (n = 8) had more or less elevated values. In patients with primary aldosteronism (n = 21) elevated as well as normal values of urinary 21-deoxyaldosterone were found, indicating that in some patients aldosterone may be formed not only from corticosterone but also from the 21-deoxy compound. In patients with 21-hydroxylase deficiency (n = 21) urinary 21-deoxyaldosterone was invariably elevated, whether the patients had the virilizing or salt-losing form of the disease. Although the clinical manifestations of the salt-losing form seem unrelated to the inability to convert 21-deoxyaldosterone to aldosterone, the determination of 21-deoxyaldosterone adds insight into the biosynthesis of aldosterone in primary aldosteronism and 21-hydroxylase deficiency.

Adolescent↗
PubMed1987

Polyacrylonitrile complement activation attenuated by simultaneous ultrafiltration and adsorption.

The highly permeable synthetic polyacrylonitrile (PAN) membrane (Filtral; Hospal, Basle) is regarded as biocompatible for its slight complement activation and leucocyte sequestration. The low C3a and C5a concentrations during PAN dialysis may be due to a lack of complement activation potential of this polymer, but also to elimination of activated complement components by the dialyser through adsorption and/or ultrafiltration (mol wt of C3a and C4a 9000 daltons; of C5a 11,000 daltons). Comparing arteriovenous differences throughout the study, higher concentrations of C3a (+23%; n.s.) and C5a (+80%; P less than 0.05) were measured in the efferent blood lines, suggesting a slight complement activation by the alternate pathway. A significantly lower C4a concentration in the efferent blood lines (-30%, P less than 0.05) indicates an elimination within the dialyser. Significantly higher arteriovenous concentration differences at the beginning of dialysis and increasing sieving coefficients suggest elimination by adsorption, mainly in the first 20 min of haemodialysis. The continuous decrease of C3a and C4a plasma concentrations in the afferent blood line suggests transport across the membrane and removal by the dialysate. Accordingly, measurable amounts of these complement components were detected in ultrafiltrate.

Acrylic Resins↗
PubMed1986

Radioimmunoassay of urinary 21-deoxytetrahydroaldosterone in primary aldosteronism and 21-hydroxylase deficiency.

A radioimmunoassay of 21-deoxytetrahydroaldosterone was developed. Normal daily excretion of the unconjugated metabolite was 1.2 +/- 1.3 micrograms and of the glucuronized metabolite, 11.9 +/- 7 micrograms. The tetrahydroaldosterone/21-deoxytetrahydroaldosterone ratio varied more in patients with primary aldosteronism than in control subjects. Thus, measurements of the urinary excretion of the tetrahydroaldosterone or 21-deoxytetrahydroaldosterone alone did not provide an accurate expression for aldosterone production. Their sum correlated well with the clinical condition, i.e. clear-cut elevation in patients with primary aldosteronism. The diminished tetrahydroaldosterone/21-deoxytetrahydroaldosterone ratio found in patients with 21-hydroxylase deficiency may be attributed to increased bacterial conversion of tetrahydroaldosterone to 21-deoxytetrahydroaldosterone but could also stem from a deficiency implicating zona glomerulosa (aldosterone biosynthesis) regardless of the stage and clinical presentation of the disease.

Adrenal Hyperplasia, Congenital↗
PubMed1986

Permeability and secondary membrane formation of a high flux polysulfone hemofilter.

It has been assumed that the molecular weight (MW) cut-off of a newly fabricated polysulfone capillary dialyzer (F60, Fresenius, FRG) is similar to that of the human glomerulus. We recently tested the device in vivo and found this not to be so, based on the device's ability to eliminate substances of a MW of 10,000 to 60,000 daltons. One of the reasons for this discrepancy was found to be the influence of secondary membrane formation on solute permeability. Endogenous marker substances of a defined MW (beta 2-microglobulin, myoglobin, RBP, alpha 1-microglobulin, acid alpha 1-glycoprotein, alpha 1-antitrypsin, prealbumin, and albumin were measured by laser nephelometry or radioimmune assay; sieving coefficients (SC) and protein eliminations were calculated for each low MW protein.

Blood↗
PubMed1986

[Significance of fundus evaluation in the staging of hypertensive disease compared to electrocardiography and renal circulation].

In order to determine the relevance of ophthalmoscopic findings in cases of hypertension as compared to electrocardiographic abnormalities and disorders of the renal function, the authors examined 728 patients admitted to the German diagnostic Clinic (Wiesbaden) with hypertension over a period of 2 years. In all cases blood pressure was measured twice, and ophthalmoscopy, electrocardiography, a chest X-ray, and a laboratory checkup were performed. The effective renal plasma flow was measured in 100 cases using the 131 iodine-Hippuran clearance method. The results revealed that ophthalmoscopy is the most reliable method for classifying early and more advanced stages of hypertension, as compared to ECG and measurement of the effective renal plasma flow.

Electrocardiography↗
PubMed1986

Human atrial natriuretic peptide (hANP) has no effect upon dopaminergic pathways: preliminary evidence in nude mice bearing heterotransplanted human CONN's adenoma tissue.

To examine whether human atrial natriuretic peptide (hANP) has an agonistic effect on dopaminergic pathways, we studied the natriuretic action and the suppressive effect of hANP on aldosterone secretion before and during treatment with haloperidol or pergolide in nude mice harbouring heterotransplanted human CONN's adenoma tissue. Nude mice with heterotransplanted tumour material without hormonal activity served as controls. The natriuretic efficacy of hANP remained unchanged by haloperidol or pergolide both in controls and in nude mice with heterotransplanted CONN's adenoma tissue. On the other hand, hANP had no effect upon the haloperidol-induced increase in aldosterone excretion in the control animals. Thus, preliminary evidence emerges that hANP has no effect on dopaminergic pathways and that the aldosterone inhibiting action of hANP is only of minor physiological significance.

Adenoma↗
PubMed1985

21-Deoxytetrahydroaldosterone excretion in primary hyperaldosteronism.

In earlier studies by our group it was shown that the urinary tetrahydroaldosterone excretion is a more reliable test for the diagnosis of primary aldosteronism than aldosterone-18-glucuronide ('urinary aldosterone'). However, in several patients with primary aldosteronism even the tetrahydroaldosterone values remained in the normal range. As the possible cause for this observation, the role of intestinal bacteria was considered which may transform tetrahydroaldosterone into 21-deoxytetrahydroaldosterone. Using a 21-deoxytetrahydroaldosterone radioimmunoassay, this hypothesis could be confirmed. The sums of the urinary 21-deoxytetrahydroaldosterone and tetrahydroaldosterone excretions revealed to be of better diagnostic value than the tetrahydroaldosterone values alone.

Adenoma↗
PubMed1985

Effects of haemodialysis on the pharmacokinetics of muzolimine.

UNLABELLED: High ceiling diuretics allow a better control of fluid balance in dialysis patients with a minimum urine flow of 500 ml/day. The pharmacokinetics of the high ceiling, long acting diuretic muzolimine (M) was investigated in 6 patients on regular dialysis therapy. METHODS: Concentrations of unchanged M in plasma were determined by high performance thin-layer chromatography (HPTLC) after a single oral dose of 240 mg up to 26 h: A) during and after the performance of dialysis lasting for 3 h, B) 20 h after finishing haemodialysis therapy (non-blind randomized cross-over study). RESULTS: The M plasma levels and the M half-lives did not differ between the two treatment groups (half-life A: 5.1 +/- 0.24 h; B: 4.8 +/- 0.51 h). The M peak concentrations were between 2 and 5 micrograms/ml and were reached 2 h post administration or even earlier. The mean M plasma levels 24 h after administration were in the same range (A: 0.33 +/- 0.16 microgram/ml; B: 0.33 +/- 0.11 microgram/ml).

Adult↗
PubMed1985

Three cases of hemodialysis-associated hypersensitivity reactions.

According to the United States Food and Drug Administration, untoward reactions to capillary hemodialyzers occur at a rate of 3.5 of every 100,000 dialyzers sold. Allergic symptoms immediately after initiation of dialysis consist of burning retrosternal pain, sensation of diffuse heat, cold perspiration, periorbital and facial edema, flushing, laryngeal stridor, bronchial hypersecretion, hypotension, bradycardia, and loss of consciousness. In 1982 Popli et al. reported four patients suffering from such allergic manifestations; three were successfully managed after being taken off dialysis. These investigators thought that inadequate rinsing of cuprammonium cellulose capillary dialyzers was responsible for the reactions, and recommended rinsing the blood compartment with 2 liters of normal saline, and the dialysate compartment with 10 liters of dialysate, both in a single-pass fashion over 20 minutes. Nichols and Platts (1982) (3) reported 15 patients with urticaria, severe bronchospasm, and shock occurring immediately after the blood had been returned from the dialyzer. These authors suggested that the sterilizing agent, ethylene oxide (ETO), was responsible. Poothullil et al. (1975) (4) described a patient with pruritus, severe dyspnea, and hypotension during dialysis. On the basis of a positive skin prick test (dermal reaction to ETO-exposed human albumin) and of antigen-induced histamine release from peripheral leucocytes, these workers suggested that ETO was responsible for the allergic reactions. Marshall et al. (1984) (5) reported that 8.9% of hemodialysis patients had positive skin tests to ETO and that 12.1% were ETO-radioallergosorbent test (RAST) positive.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1983

Aldosterone metabolites and possible aldosterone precursors in hypertension.

The value of the urine tests: free aldosterone, aldosterone-18-glucuronide, tetrahydroaldosterone 18-hydroxycorticosterone and 18-hydroxydeoxycorticosterone in distinguishing primary aldosteronism from essential hypertension was studied in patients with typical and atypical primary aldosteronism and in patients with essential hypertension. The discriminating function of the tetrahydroaldosterone determination was the best, followed by 18-hydroxycorticosterone, free aldosterone and aldosterone-18-glucuronide. The measurement of 18-hydroxydeoxycorticosterone was without distinguishing value. Three cases with hypertension, adrenal adenoma, elevated 18-hydroxycorticosterone but normal aldosterone values were observed. In longitudinal studies the excretions of aldosterone, aldosterone metabolites and possible precursors periodically varied independently of each other. Determinations of urine aldosterone, aldosterone metabolites, 18-hydroxycorticosterone and 18-hydroxydeoxycorticosterone were not applicable for differential diagnosis of the adenoma and hyperplasia forms of primary aldosteronism.

Adenoma↗
PubMed1982

Increased excretion of 18-hydroxycorticosterone in patients with adrenal adenomas and hypertension.

Two female patients, 54 and 34 years old, each presented with an adrenal adenoma and hypertension. Blood pressure fell after removal of the tumors. The first patient had high urinary 18-hydroxycorticosterone and periodically elevated 18-hydroxy-deoxycorticosterone excretions. The second patient had elevated 18-hydroxycorticosterone and free cortisol excretions. Urinary aldosterone, aldosterone metabolites and plasma aldosterone were not increased. Plasma renin activity was suppressed and serum potassium levels were normal. After surgery, no elevated steroid values were found. Elevated 18-hydroxycorticosterone excretion may be an indicator of yet unknown hypertensinogenic mechanisms. The role of 18-hydroxycorticosterone in the etiology of hypertension is still unknown.

18-Hydroxycorticosterone↗
PubMed1982

Direct radioimmunoassays for "aldosterone" and "18-hydroxycorticosterone" in unprocessed urine, and their use in screening to distinguish primary aldosteronism from hypertension.

For distinguishing primary aldosteronism from essential hypertension, we use simple direct radioimmunoassays for "aldosterone" (aldosterone and other materials that react with the antibody to aldosterone) and "18-hydroxycorticosterone" (similarly) in unprocessed urine. Patients with primary aldosteronism have high values for "aldosterone." This diagnosis can be validated by assays of further urine samples from the same person and by additional direct assays for "18-hydroxycorticosterone." In none of 65 urine samples from 26 patients with primary aldosteronism were both "aldosterone" and "18-hydroxycorticosterone" values within their reference intervals. However, a few "aldosterone" and "18-hydroxycorticosterone" values for patients with essential hypertension and normal aldosterone excretion were also (moderately) increased. Thus, when high values are found, true aldosterone values must be estimated by extraction and chromatography, to eliminate false positives. The "aldosterone" and "18-hydroxycorticosterone" values by our procedure are much higher than the corresponding values for urinary free aldosterone and 18-hydroxycorticosterone. Although not identified, the immunoactive materials are probably metabolites of aldosterone and 18-hydroxycorticosterone.

18-Hydroxycorticosterone↗
PubMed1982

[Hepatic artery embolization for treatment of the carcinoid syndrome].

In two patients with carcinoid syndrome and liver metastases embolization of the hepatic arteries was successful. In one case re-embolization was accomplished after one year. Embolization was followed by diminuation of serotonin-metabolites in the urine. The clinical symptoms improved, resulting in better quality of the patients lives. Embolization is to be preferred to application of systemic cytotoxic medication in cases of carcinoid syndrome with disseminated liver metastases.

Adult↗