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Biomedical subjects

K C Siamopoulos

Publications and source records attributed to K C Siamopoulos.

At least 37 records · Page 2Linked to original sources
PubMed1999

Increased platelet reactivity to the aggregatory effect of platelet activating factor, in vitro, in patients with heterozygous familial hypercholesterolaemia.

Patients with familial hypercholesterolaemia (FH) present with high plasma total- and low density lipoprotein (LDL)-cholesterol levels and develop premature and often severe atherosclerosis. Elevations of total- and LDL cholesterol levels are not only related to an increased risk of atherosclerosis, but may also exert prothrombotic effects via platelet activation leading to acute coronary events. In the present work, the platelet response to the aggregatory effect of platelet-activating factor (PAF) in relation to the plasma PAF-acetylhydrolase (PAF-AH) activity and to their lipidemic profile was studied in 20 heterozygous FH patients. The PAF EC(50) aggregation values in the patient group were significantly decreased ( P < 0.03) compared with the control group (19.5 5.2 nM and 30.4 7.2 nM, respectively). Moreover, the maximal percentage of aggregation to 100 nM PAF was significantly increased in the patient group compared with controls (26.5 8.2% vs 15.2 3.1%, respectively, P < 0.03). Both platelet aggregation parameters were correlated to the plasma total- and LDL-cholesterol levels, as well as to the apolipoprotein B (apo B) levels. The maximal percentage of aggregation to 10 microM ADP was also significantly increased in the patient group compared with controls (51.5 10.3% vs 32.4 9.0%, respectively, P < 0.02) but was not correlated to any plasma lipid parameter. The total plasma PAF-AH activity in the heterozygous FH patients was significantly higher compared with controls (109.8 15.9 nmol/ml per min vs 68.4 18.0 nmol/ml per min, respectively, P < 0.0001), whereas the HDL-associated PAF-AH activity did not differ significantly between the two groups. Our results suggest that the increased aggregatory response of platelets to PAF despite the significantly higher plasma PAF-AH activity, could be an important factor contributing to the higher atherogenicity and incidence of acute coronary events observed in patients with heterozygous FH.

Journal Article↗
PubMed1999

Effect of micronized fenofibrate and losartan combination on uric acid metabolism in hypertensive patients with hyperuricemia.

It has been reported that micronized fenofibrate and losartan can significantly decrease serum uric acid levels by augmenting uric acid excretion. We undertook this study to evaluate the effects of the combination treatment with micronized fenofibrate and losartan in nondiabetic hypertensive dyslipidemic patients with hyperuricemia (serum uric acid, >7 mg/ dl). A total of 25 patients (15 men, 10 women) aged 21-66 years was studied. In all patients, serum lipid parameters, including Lp(a), fibrinogen, and uric acid levels, as well as fractional excretion of uric acid (FEUA) were obtained before treatment, 8 weeks after micronized fenofibrate treatment (200 mg daily), and 8 weeks after combination therapy with micronized fenofibrate (200 mg daily) and losartan (50 mg daily). Fenofibrate alone significantly decreased total cholesterol, low-density lipoprotein (LDL) cholesterol, triglycerides, Apo B, Lp(a), fibrinogen, and uric acid levels (from 7.6+/-0.55 to 5.6 +/-0.5 mg/dl; p < 0.0001) and increased high-density lipoprotein (HDL) cholesterol, Apo A1, and FEUA (from 6.5+/-1.8% to 12.2+/-4%; p < 0.0001). The addition of losartan beyond the decrease in blood pressure values did not significantly alter serum metabolic parameters. However, a small additional decrease in serum uric acid levels (from 5.6+/-0.5 to 4.9+/-1 mg/dl; p < 0.05) was found because of a further increase in FEUA (from 12.2+/-4% to 14+/-5.5%; p < 0.05). It is concluded that the combination of micronized fenofibrate and losartan is useful for the management of patients with multiple metabolic abnormalities, including hyperuricemia.

Adult↗
PubMed1999

Blood pressure profile in patients with microvascular angina.

Normotensive patients with microvascular angina exhibit increased diastolic blood pressure and blood pressure loads during daily activities and decreased diurnal variation of systolic blood pressure, compared with age- and sex-matched normotensive controls. The abnormal blood pressure profile could play a role in the pathogenesis of microvascular angina.

Adult↗
PubMed1999

Prerenal azotemia in a diabetic patient with hyporeninemic hypoaldosteronism and autonomic neuropathy.

Patients with hyporeninemic hypoaldosteronism show mild to moderate renal insufficiency, with a creatinine clearance of 20-75 ml/min, and asymptomatic hyperkalemia. A low degree of sodium wasting and mild hyperchloremic metabolic acidosis are also usually present. However, severe sodium wasting and volume depletion are not typically seen unless the patient is placed on severe sodium restriction or has some other cause of extrarenal sodium loss. In fact, acute renal failure has not been reported in such patients. We describe a diabetic patient with hyporeninemic hypoaldosteronism and autonomic neuropathy who developed recurrent episodes of acute renal failure due to prerenal azotemia during acute exacerbations of diarrhoea. In our case, despite significant hypovolemia, the renin-aldosterone axis was markedly suppressed, implying that sympathetic tone played a decisive role in renin regulation.

Aged↗
PubMed1998

Antibodies to hepatitis E virus among several populations in Greece: increased prevalence in an hemodialysis unit.

BACKGROUND: Hepatitis E virus (HEV) has been found to be the causative agent of enterically transmitted non-A, non-B hepatitis in tropical and subtropical countries. Several investigators, however, have indicated that HEV could be endemic in Europe, albeit at a low prevalence. STUDY DESIGN AND METHODS: The purpose of this study was to estimate the prevalence of anti-HEV in various populations in northwestern Greece (Epirus region). Healthy blood donors (2636), refugees from southern Albania (350), children (165), injecting drug users (IDUs) (65), multiply transfused patients (62), patients with chronic viral hepatitis (75), and chronic hemodialysis patients (149) were investigated for anti-HEV by enzyme immunoassay and confirmatory Western blot assay. In addition, 380 consecutive healthy blood donors and 62 hemodialysis patients from a neighboring area (Agrinion, Greece) were investigated. RESULTS: A very low presence of anti-HEV antibody was found among healthy blood donors from Epirus (0.23%) and Agrinion (0.53%). Anti-HEV was not detected in children, IDUs, or multiply transfused patients. In contrast, a low but significant prevalence of anti-HEV was found among refugees (4.85%), patients with chronic viral hepatitis (5.3%), and hemodialysis patients from Epirus (1.34%), as compared with healthy blood donors from Epirus: p < 0.0001, p < 0.00001, and p < 0.10, respectively. A high prevalence (9.7%) of anti-HEV was revealed in patients at the hemodialysis unit of the General Hospital of Agrinion (p < 0.00005, compared to healthy blood donors from Agrinion). No significant association was found between anti-HEV positivity and the age or sex of donors, the duration of hemodialysis, positivity for hepatitis B or C virus infection markers, history of hepatitis, increased alanine aminotransferase, renal transplantation, a history of transfusion, or the number of units transfused. CONCLUSION: This study demonstrated a high prevalence of anti-HEV in a separate hemodialysis unit, without an association with the known routes of transmission of blood-borne viruses. This observation suggests that a still-undefined intra-unit factor or other factors are associated with HEV transmission.

Adolescent↗
PubMed1998

Absence of HCV viraemia in anti-HCV-negative haemodialysis patients.

BACKGROUND: Immunologic alterations have been reported in chronic haemodialysis (HD) patients. Some HD patients may have, therefore, an inability to produce detectable amounts of serum antibodies to hepatitis C virus (anti-HCV). Previous studies have shown the presence of HCV viraemia in anti-HCV-negative HD patients (ranging from 1 to 15%). However, the universal epidemiologic impact of these cases remains uncertain since there are conflicting results. In this context, we conducted a study in an attempt to investigate the presence of HCV viraemia among anti-HCV-negative HD patients in a well-defined geographic area of the northwestern part of Greece. METHODS: During a 6 month period, 81 anti-HCV-negative HD patients were tested twice for the presence of HCV RNA, using the reverse transcriptase polymerase chain reaction (RT-PCR) combined with a DNA enzyme immunoassay (DEIA). At the same time, periodic testing for anti-HCV by two commercially available third generation assays was done. In addition, 15 anti-HCV-positive HD patients and 20 non-HD patients with well established chronic HCV infection used as internal controls were tested for the presence of HCV RNA and anti-HCV. RESULTS: None of the anti-HCV-negative HD patients were shown to be viraemic by the combined RT-PCR and DEIA method. During the same time period, all remained anti-HCV negative by the third generation assays. By contrast, all the patients with known HCV-infection were positive by the two enzyme immunoassays, whereas 13 anti-HCV-positive HD patients (86.7%) and 18 non-HD patients (90%) were viraemic by RT-PCR. CONCLUSIONS: This study demonstrated that routine HCV RNA testing in anti-HCV-negative HD patients appears not to be necessary particularly when third generation assays are used for the detection of anti-HCV.

Adolescent↗
PubMed1998

Effect of L-carnitine supplementation on lipid parameters in hemodialysis patients.

It has been reported that cumulative carnitine losses through dialysis membranes may worsen hyperlipidemia during long-term hemodialysis. However, carnitine supplementation has not shown a consistent beneficial response. We undertook the present study to determine if there is any hypolipidemic effect of L-carnitine on Greek dialysis patients in concert with the dialysate buffer composition (acetate or bicarbonate). A total of 28 patients (16 male, 12 female), mean age 43 years (range 21-61), with end-stage renal disease on maintenance hemodialysis for a mean period of 25 months (range 7-84) were studied. The dialysis schedule was 4 h, 3 times/week using cuprophane hollow-fiber dialyzers and acetate (n = 14) or bicarbonate (n = 14) dialysate. In all patients L-carnitine (5 mg/kg body weight) was infused intravenously 3 times/week at the end of each hemodialysis session. Blood samples for carnitine and lipid determinations were obtained before treatment, and 3 and 6 months following treatment. Even though L-carnitine did not modify most of the serum lipid levels, a significant decrease in serum triglycerides was evident in the whole group of patients (from 225 +/- 76 to 201 +/- 75 mg/dl, p = 0.03). Furthermore, L-carnitine could decrease serum triglycerides only in hypertriglyceridemic patients (from 260 +/- 64 to 226 +/- 82 mg/dl, p < 0.05). L-Carnitine resulted in a reduction of serum triglycerides in both patients on bicarbonate and on acetate dialysis, while there were no significant differences in the changes of lipid parameters after L-carnitine between the two groups of hemodialysis patients. We conclude that relatively low doses of L-carnitine supplementation could contribute to the management of some hypertriglyceridemic hemodialysis patients.

Adult↗
PubMed1998

Multiple electrolyte abnormalities after pamidronate administration.

Pamidronate constitutes a major advance in the treatment of tumor-associated hypercalcemia. However, transient electrolyte abnormalities have been reported after pamidronate administration. We describe here a patient with multiple myeloma and severe hypercalcemia who developed transient but significant electrolyte disturbances (mainly hypophosphatemia and hypomagnesemia) after a single dose of 90 mg of pamidronate, focusing on the underlying pathophysiological mechanisms.

Antineoplastic Agents↗
PubMed1998

Paraquat-induced renal injury studied by 1H nuclear magnetic resonance spectroscopy of urine.

The herbicide paraquat (1,1'-dimethyl-4,4'-bipyridylium dichloride; PQ), is a poison known to cause delayed mortality due to lung and kidney injuries. High-resolution proton nuclear magnetic resonance (1H NMR) spectroscopy has been extensively applied in evaluating nephrotoxicity by the characteristic perturbations in the excretion pattern of low molecular weight endogenous metabolites. The application of the method allows the rapid localization of the renal injury noninvasively. In this study, we report 1H NMR and conventional clinical chemistry urinalysis in two patients suffering from paraquat intoxication after overdose with suicidal intent. The alterations in the urine NMR spectrum suggest necrosis of the pars recta of the proximal renal tubules. The molecule of paraquat is also clearly detected in the same spectrum. In conclusion, the rapid screening of urine by NMR spectroscopy provides information about both the identity of the poison and the abnormal pattern of endogenous metabolites that characterize the location of the injury in renal tubules and reveals alterations in unusual metabolites that are not commonly measured.

Adult↗
PubMed1997

Lipid abnormalities in Greek patients with coronary artery disease.

Lipid abnormalities are major risk factors for premature coronary artery disease (CAD). However, the type and prevalence of dyslipidemia in these patients have not been well characterised, especially in some ethnic groups. The purpose of the present work was to determine the lipid disorders in patients of Northwestern Greece with premature CAD. The study population comprised of 132 men and 38 women who underwent elective diagnostic arteriography in our University Hospital. Subjects with > or = 1 lesion that narrowed the lumen of any of the 15 coronary artery segments by > or = 70% were considered to be CAD cases (n=108), whereas those with narrowing < 70% were excluded (n=54). Asymptomatic subjects (n=104) matched for age and sex were taken as controls. Compared with the controls, patients with premature CAD had increased serum levels of total cholesterol, LDL cholesterol, triglycerides, Apo B, and Lp(a), and decreased serum levels of HDL cholesterol and Apo A1. A lipoprotein or apolipoprotein abnormality was identified in 89 CAD patients (82.4%). The increased serum Apo B level (> 130 mg/dl) was the most common lipid abnormality observed in 72 patients. However, the most prevalent dyslipidemic phenotypes in our patients were type IIA followed by hypoalpha and hyperApoB. Compared to the control population, CAD patients had increased incidence of IIA and hypoalpha phenotypes. On the contrary, a normal lipoprotein phenotype was more common in the control population compared to CAD patients (56.7% vs. 17.6%, P<0.001). We conclude that the majority of Greek patients with premature CAD exhibit lipid and lipoprotein abnormalities, which to a large extent can be defined by determining the traditional lipid parameters (total cholesterol, LDL cholesterol, HDL cholesterol and triglycerides). However, in some cases the value of the quantification of other lipid parameters such as apolipoproteins and Lp(a) should be taken into account.

Aged↗
PubMed1997

Increased serum levels of interleukin-1beta in the systemic circulation of patients with essential hypertension: additional risk factor for atherogenesis in hypertensive patients?

The dysfunction of the immune system has been implicated in the cause of essential hypertension (EH). On the other hand, interleukin- 1beta (IL-1beta) has strongly been involved in the pathogenesis of atheromatosis, whereas our preliminary experiments in serum samples from hypertensive patients before any drug therapy have shown the presence of high concentrations of IL-1beta and the absence of interleukin-2 (IL-2). The aim of this study was first to confirm our preliminary findings and second to investigate the possible interrelation(s) among the parameters studied, particularly between the immunologic markers and the blood pressure or the lipid parameters, because so far there are no data regarding the possible participation of IL-1beta in the cascade phenomena presented during the process of EH such as atherogenesis. Serum samples from 28 consecutive unselected patients with EH before any drug administration or after discontinuation of the antihypertensive therapy for at least 4 weeks, 31 normotensive patients with familial hypercholesterolemia (FH, disease control group), and 35 healthy individuals In a control group matched for age and sex were investigated for the presence of IL-1beta (commercial enzyme immunoassay), soluble IL-2 receptors (slL-2Rs, sandwich enzyme-linked immunosorbent assay set up in our laboratory), and some of the acute phase proteins by nephelometry. In addition, total cholesterol, triglycerides, high-density lipoprotein cholesterol, low-density lipoprotein cholesterol, apolipoproteins A1 and B, and lipoprotein (a) were determined by standard methods. The data were analyzed by unpaired t test, Mann Whitney-U, chi-squared analysis after Yate's correction, analysis of variance, or Kruskal-Wallis where applicable. Correlation coefficient was calculated by simple regression analysis (r) or nonparametric Spearman correlation coefficient (rs). We found that (1) none of the patients had increased concentrations of sIL-2Rs, and (2) the IL-1beta levels significantly differed in the three groups (p = 0.0001). In more detail, the concentrations of IL-1beta were significantly higher in patients with EH compared with those in patients with FH (p < 0.0005) and the healthy control group (p = 0.0001). By contrast, the IL-1beta concentrations did not differ between patients with FH and the healthy control group. (3) Sixteen (57.1%) patients with EH and only 6 (19.4%) patients with FH (p < 0.01) had increased levels of IL-1beta, and (4) the IL-1beta was not correlated with the acute phase reactants or the lipid parameters in the groups studied. However, the group of patients with EH and increased IL-1beta levels had significantly higher mean concentrations of triglycerides (p < 0.05) and significantly lower mean concentrations of high-density lipoprotein cholesterol (p < 0.05) than those who had IL-1beta levels lower than the cutoff point. (5) The IL-1beta concentrations were positively though slightly correlated with the mean blood pressure only in the group of patients with EH (r = 0.38, p < 0.05). This study demonstrated the presence of high concentrations of IL-1beta and the absence of indicators of cellular immune activation in the systemic circulation of patients with EH, suggesting that this cytokine may be involved in the pathogenesis of EH. In addition, this study showed that the high levels of IL-1beta were associated with lipid indicators of atheromatosis only in the group of patients with EH. More studies are required in an attempt to address whether IL-1beta could have a pathogenetic importance in EH. Taking into account these findings, however, it can be suggested that the presence of high IL-1beta levels may be an additional and perhaps independent risk factor for atheromatosis in patients with EH.

Acute-Phase Proteins↗