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A Vyzantiadis

Publications and source records attributed to A Vyzantiadis.

9 recordsLinked to original sources
PubMed2003

Cyclosporine and its metabolites before and 2 h post-dose: comparative measurements of a monoclonal and a polyclonal immunoassay.

The aim of the study was to investigate the better accuracy of the 2-h post-dose (C2) levels of cyclosporine (CyA), compared with the pre-dose (C0) levels and to evaluate the results measured by a monoclonal or a polyclonal immunoassay. The parent compound of CyA in C2 (monoclonal2) was measured in 53 kidney transplant patients by the monoclonal fluorescence polarization method, as well as the parent compound plus metabolites (polyclonal2) by the polyclonal fluorescence polarization method. Also, the parent compound was measured in 21 of the patients for the C0 (monoclonal0), whereas the parent compound plus metabolites in 36, for the C0 (polyclonal0). As level of metabolites was considered the difference between polyclonal and monoclonal values (polyclonal-monoclonal), either in C0 (metabolites0) or in C2 (metabolites2). The ratio polyclonal2/monoclonal2 gave a mean value of 1.7+/-0.2 (mean+/-SD), whereas the mean value of the ratio polyclonal0/monoclonal0 was 2.3+/-0.6, with almost double variation. The mean value of the ratio metabolites2/monoclonal2 was 0.7+/-0.2 and of the ratio metabolites0/monoclonal0 was 1.3+/-0.6. The difference between the two ratios is very significant (p = 0.000001) and they are not correlated with each other (r = 0.18, p = 0.44). The measurements of monoclonal0 and polyclonal0 or monoclonal2 and polyclonal2 are very significantly correlated (r = 0.94, p = 0.000001 and r = 0.97, p = 0.000001, respectively). In C0 the proportion of metabolites is higher than in C2, with a double variation, as the degree of metabolism is diverse. Consecutively, in monoclonal methods, as cross-reactions occur with metabolites, it is more accurate to use the C2 measurement for the evaluation of CyA. The application of both methods, the polyclonal and the monoclonal, could be a useful tool as it gives an estimation of metabolites whose degree of contribution to the immunosuppressive result is difficult to ascertain. Finally, if for reasons of clinical experience, the polyclonal method is used, then the mean therapeutic levels of polyclonal2 are 1.5-1.7 compared with monoclonal2.

Cyclosporine↗
PubMed1996

Angiotensin converting enzyme gene polymorphism is not related to essential hypertension in a Greek population.

Studies in various ethnic groups have shown contradictory evidence on the association of the angiotensin converting enzyme (ACE) insertion/ deletion (I/D) polymorphism with essential hypertension. In addition, mistyping of the insertion allele in heterozygotes has been reported. We analyzed the ACE genotype of 98 hypertensive and 84 normotensive subjects of Greek origin. Genomic DNA was extracted from blood samples and amplified by polymerase chain reaction (PCR). PCR primers were flanking the polymorphic region in intron 16 of the ACE gene. To avoid mistyping of heterozygotes, samples with the DD genotype were also amplified with primers that detect only the insertion allele. The distribution of the DD, ID, and II ACE genotypes was 30, 45, and 23 in hypertensive patients and 29, 40, and 15 in normotensive subjects, respectively. The estimated frequency of the insertion allele was 0.45 in hypertensive and 0.42 in normotensive subjects. The difference was not statistically significant. The results indicate a lack of association between ACE I/D polymorphism and essential hypertension in this Greek population, suggesting that other genes must contribute to the pathogenesis of hypertension.

Alleles↗
PubMed1994

The relationship between the sympathetic nervous system and the renin-angiotensin system in renovascular hypertension.

UNLABELLED: The aim of this study is to evaluate and compare the activity of the sympathetic nervous system and the renin-angiotensin system in patients with unilateral or bilateral renovascular hypertension. Plasma noradrenaline (plNA) levels and plasma renin activity (PRA) were measured simultaneously in blood samples obtained both from a peripheral vein and from the renal veins, during catheterization of the venous cava system, in 17 patients with unilateral (group A) and in 9 patients with bilateral renal artery stenoses (group B). RESULTS: peripheral plNA levels were elevated in 6/17 patients of the group A and 3/9 patients of the group B, while in the remaining 11/17 and 6/9 were normal, respectively. The comparison of plNA levels between the renal veins showed that in both groups plNA levels were higher in the renal vein of the ischaemic (group A) or the more ischaemic kidney (group B), and the difference was statistically significant. Renal vein renin ratio was above 1.5 in both groups. Renin hypersecretion from the ischaemic or the more ischaemic kidney compared to renin suppression from the normal or the less ischaemic kidney showed statistically significant difference.

Humans↗
PubMed1992

Visual evoked potentials in hypothyroid and hyperthyroid patients before and after achievement of euthyroidism.

Thyroid hormone deficiency is frequently associated with central nervous system (CNS) disturbances such as mental retardation, convulsions, coma etc. Studies of quantitative changes in CNS in hypo- or hyperthyroidism are scarce. Evoked potentials is a good method of assessing the electrical response of the brain to different (visual, acoustic, somatosensory) stimuli and has been used extensively in the study of brain disturbances and to a lesser degree in metabolic diseases. We studied the visual evoked potentials (latency and amplitude) in 12 patients with hyperthyroidism and 15 patients with hypothyroidism, before treatment and after they became euthyroid. Four of the hyperthyroids (33%) had abnormally prolonged (> 104 msec) latencies before therapy. Two of them had clinical exophthalmos. No change was observed after euthyroidism was achieved. On the contrary 7 out of 15 (47%) hypothyroids had abnormally prolonged latencies which became normal in 4 when euthyroidism was achieved. Amplitude was lower than normal in 6 and became normal only in one of them after treatment. None of the hyperthyroid patients had amplitude changes. In conclusion, hypothyroid patients may have changes in the amplitude and/or the latency of visual evoked potentials which are reversible to a great extent with thyroxine. Evoked potentials is another method of studying in humans the metabolic effects of thyroxine deficiency in CNS.

Adult↗
PubMed1992

TSH-secreting pituitary macroadenoma in an 11-year-old girl.

Graves' disease, multinodular toxic goiter or toxic adenoma are the usual causes of hyperthyroidism in children as well as in adults. We report a case of hyperthyroidism due to TSH-secreting pituitary macroadenoma in an 11-year-old girl. The patient was admitted to the Endocrine Department for pituitary function evaluation, five months after transfrontal adenomectomy and pituitary irradiation for a macroadenoma. On admission the patient was clinically hyperthyroid and the work-up established a diagnosis of hyperthyroidism due to TSH-secreting adenoma (high levels of TSH in the face of hyperthyroidism, no TSH response to TRH stimulation, diffuse thyroid goiter without eye signs or pretibial myxedema). Of interest in this case was the fact that: (a) she is the youngest patient reported with hyperthyroidism due to a TSH-secreting macroadenoma and (b) hyperthyroidism was diagnosed after adenomectomy.

Adenoma↗
PubMedDate not supplied

Serum concentrations of insulin-like growth factor-I (IGF-I) in patients with liver cirrhosis.

BACKGROUND/AIMS: Insulin-like growth factor-I is an important anabolic polypeptide with various effects. The circulating insulin-like growth factor-I is mainly liver derived. The aim of this study was to determine insulin-like growth factor-I serum levels in patients with cirrhosis and to clarify their association with patients' clinical condition and the etiology of cirrhosis. METHODOLOGY: Forty patients with liver cirrhosis were enrolled. Cirrhosis was in 22 cases induced by virus, in 10 due to primary biliary cause and in the rest 8 of alcoholic origin. The Child score index was found as A (n = 26), B (n = 9), C (n = 5). Twenty, age-matched healthy subjects, were used as a control group. Serum insulin-like growth factor-I was measured by an immunoradiometric assay in all subjects. RESULTS: Serum insulin-like growth factor-I levels in liver cirrhosis were found very significantly lower than in healthy individuals (57.4 +/- 7.0 ng/mL vs. 198.8 +/- 16.3 ng/mL, p = 0.0000001). In liver cirrhosis insulin-like growth factor-I was negatively correlated with spleen enlargement (r = -0.46, p = 0.0031). Child B and C patients showed significantly reduced insulin-like growth factor-I levels in comparison to patients staged as Child A (28.9 +/- 3.0 ng/mL vs. 72.8 +/- 9.3 ng/mL, p = 0.0016). The comparison of 12 patients with viral induced cirrhosis (Child A) to 14 patients with non-viral cirrhosis, of the same clinical stage, showed non-significant difference (84.2 +/- 16 ng/mL vs. 63.1 +/- 10.3 ng/mL, p = 0.27). CONCLUSIONS: Insulin-like growth factor-I synthesis is disturbed in liver cirrhosis and reflects the severity of the clinical stage. It represents a good marker of hepatic function. The etiology of cirrhosis does not seem to influence its levels.

Adolescent↗
PubMedDate not supplied

The effect of spironolactone in hypertensive patients on regular haemodialysis and after renal allotransplantation.

To determine the role of the renin-angiotensin-aldosterone system in the maintenance of hypertension in patients with end stage renal disease, twenty four hypertensive patients were studied on regular haemodialysis treatment (RDT) and after successful kidney transplantation. The first group consisted of nine patients on RDT with their own kidneys in situ, and the second group consisted of nine kidney transplants. All 18 patients were given spironolactone 300 mg daily for three weeks following a control period of the same duration. In addition, three anephric patients on RDT were studied with the above protocol and three other patients on RDT were given the same dose for only six days. Blood pressure (BP), body weight, plasma K-Na, aldosterone and renin activity in all patients, and Na and aldosterone in urine in the second group were measured. In the first group of patients on RDT plasma potassium and renin activity increased significantly but BP remained unchanged. In the second group of transplanted patients plasma potassium, renin activity, and aldosterone were increased and BP diminished significantly. In the group of three anephric patients plasma potassium increased but plasma renin activity remained very low. Finally, in the patients on dialysis who received spironolactone for only six days there was a parallel increase of serum potassium and plasma renin activity. These findings suggest that in patients on RDT spironolactone stimulates renin secretion and potassium retention possibly by an effect on the remaining nephrons and/or the intestinal wall. On the contrary, in the transplanted patients the effect of spironolactone on the renal tubule is capable of producing sodium depletion and fall in BP.

Adult↗