K Siamopoulos

University of Ioannina, Ioánnina, Ipeiros, Greece

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Publications (31)86.09 Total impact

  • Inflammatory Bowel Diseases 02/2010; 16(11):1824-5. · 5.12 Impact Factor
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    ABSTRACT: BACKGROUND The purpose of the present study was to investigate hypoxemic complications of limbs with arteriovenous access by means of transcutaneous oximetry.METHODS The study was a prospective assessment of 31 limbs with arteriovenous access using transcutaneous oximetry. Each limb was measured 4 times: before arteriovenous construction, the first post-operative day, the first post-operative month, and the fourth post-operative month. The contralateral limb was used as control for every measurement.RESULTSThe first postoperative day was characterized by an acute drop in the tissue oxygenation of the limb with arteriovenous access (p = 0.03). This hypoxia was compensated for in the first month by a gradual return of transcutaneous oxygen values to pre-operative levels. Two patients developed a steal syndrome, characterized by abnormally low transcutaneous oxygen (< 40 mmHg).CONCLUSION Transcutaneous oximetry is a simple and accurate method for objectively assessing the whole spectrum of alterations in tissue oxygenation (from transient hypoxia to steal syndrome) caused by arteriovenous access.
    Dialysis & Transplantation. 02/2008; 37(2):67 - 70.
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    ABSTRACT: Cystinuria is a complex genetic disorder. In the present study, we report on the strict linkage disequilibrium of SLC7A9 mutations with the wild type SLC7A9 haplotype of 15 single nucleotide polymorphisms (SNPs) and their effect on cystinuria manifestation and classification. Specifically, screening for mutations and polymorphisms was performed in the family members of ten cystinuric patients with SLC7A9 gene mutations. The molecular genetic and clinical data of cystinuric patients and their relatives were combined to construct the SLC7A9 SNP haplotypes and evaluate the manifestation of the disorder in carriers for a SLC7A9 gene mutation. It was found that all carriers of a SLC7A9 mutation manifested cystinuria if their normal allele had non-wild type nucleotides in two or more of the identified polymorphic sites. Subsequently, the polymorphic background of the SLC7A9 gene probably affects the expression of the disorder in SLC7A9 mutation carriers and points to a revised genetic classification of cystinuric patients.
    Urological Research 11/2006; 34(5):299-303. · 1.59 Impact Factor
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    ABSTRACT: Various laparoscopic techniques have been described for the insertion of peritoneal dialysis catheters. However, most use 3 to 4 ports, thus multiplying the potential risk for abdominal wall complications (hemorrhage, hernia, leaking). A Tenckhoff catheter was placed laparoscopically, using just 1 port, in 13 consecutive patients with end-stage renal failure. All catheters were fixed in the abdominal cavity with no additional ports for this purpose. After a follow-up of 76 patient-months, all catheters are working properly. There were no postoperative wall hemorrhages, early leaking, or hernias. There was 1 case of catheter migration and 2 cases of late leaking in 2 patients in total, due to severe constipation. There were no exit site or tunnel infections. One episode of peritonitis was successfully treated with antibiotics. The simplicity and the rapidity of the method justifies serious consideration for its use as the standard Tenckhoff catheter placement.
    The American Journal of Surgery 08/2006; 192(1):125-9. · 2.52 Impact Factor
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    ABSTRACT: The prevalence and significance of sleep-disordered breathing (SDB) in dialysis-independent chronic renal failure (CRF) remains unknown. We studied the presence of SDB in nondialyzed CRF patients. Diagnostic polysomnography was performed in consecutive stable nondialyzed CRF patients. Inclusion criteria were age <or=70 years, absence of systolic dysfunction or history of pulmonary edema, FEV(1) > 70% pr, absence of neurologic disease or hypothyroidism, and calculated creatinine clearance <40 ml/min. Thirty-five patients (19 male, 16 female) were studied. An apnea-hypopnea index (AHI) >or=5/h was present in 54.3% (almost exclusively obstructive events). AHI correlated with urea (r = 0.35, p = 0.037), age (r = 0.379, p = 0.025), and body mass index (BMI) (r = 0.351, p = 0.038), but not with creatinine clearance. AHI or SDB were unrelated to gender. In nondiabetics (n = 25), AHI correlated with urea (r = 0.608, p = 0.001) and creatinine clearance (r = -0.50, p = 0.012). Nondiabetics with severe CRF (calculated GFR < 15 ml/min/1.73 m(2)) had a significantly higher AHI compared with less severe CRF. Restless legs syndrome (RLS) was present in 37.1% and periodic limb movements in 28.6%. Daytime sleepiness was not associated with respiratory events, but was more common in patients with RLS. The prevalence of SDB and RLS is high in dialysis-independent CRF. SDB weakly correlates with indices of kidney function and this association becomes stronger in nondiabetics.
    Beiträge zur Klinik der Tuberkulose 01/2006; 184(1):43-9. · 2.06 Impact Factor
  • Atherosclerosis Supplements - ATHEROSCLER SUPPL. 01/2005; 6(1):140-140.
  • Atherosclerosis Supplements - ATHEROSCLER SUPPL. 01/2005; 6(1):141-141.
  • Atherosclerosis Supplements - ATHEROSCLER SUPPL. 01/2004; 5(1):132-132.
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    ABSTRACT: Preeclampsia is considered to be a multifactorial and multisystemic disorder with a genetic predisposition. Alterations in the renin-angiotensin system are considered to play a significant role in the pathogenesis of the disease. In order to investigate the possible association of the three most common polymorphisms of the renin-angiotensin system genes with preeclampsia we have examined 41 women with preeclampsia and 102 normotensive pregnant women. DNA samples were genotyped for the M235T polymorphism of the angiotensinogen gene (AGT), the insertion/deletion (I/D) polymorphism of the angiotensin-converting enzyme gene (ACE) and the A1166C polymorphism of the angiotensin II type 1 receptor gene (AT1R) by PCR. Allele and genotype frequencies of the AGT gene polymorphism differed between the two study groups. The TT genotype of the M235T polymorphism was significantly increased in women who developed preeclampsia (P<0.02). In addition, women with preeclampsia and TT genotype had more frequently the DD genotype or the 1166C allele than the control group showing a significant interaction between the genes. In conclusion, we found an association between the angiotensinogen variant 235T and preeclampsia as well as an interaction between the variant 235T and the two other genes studied.
    European Journal of Obstetrics & Gynecology and Reproductive Biology 10/2003; 110(1):8-11. · 1.84 Impact Factor
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    ABSTRACT: There are limited data regarding qualitative lipoprotein abnormalities in undialysed uremic patients without proteinuria. In this report, we focused on lipoprotein changes observed in uremic patients with proteinuria as well as on the susceptibility of low-density lipoprotein (LDL) of these patients to oxidative modification in vitro. 20 patients with chronic renal failure [serum creatinine >1.6 mg/dl (141.4 micromol/l)], but not yet on renal replacement therapy, and with heavy proteinuria (>2 g/24 h), and 18 age- and sex-matched healthy individuals participated in the study. In both patients and controls, venous blood was collected for determination of serum lipid and lipoprotein levels, lipoprotein subfraction profile and chemical composition, as well as the susceptibility of LDL subfractions to oxidation. Patients exhibited a more atherogenic lipid profile compared with the control population. Furthermore, the total very LDL + intermediate-density lipoprotein mass was increased in patients compared with controls, while this subfraction was triglyceride enriched in uremic patients. The total LDL concentration was significantly higher in patients compared with controls due mainly to an increase in the mass of all lipoprotein subfractions. It is noteworthy that the mass of small dense LDL was significantly elevated in patients compared with controls (135 +/- 12 vs. 115 +/- 11 mg/dl, p = 0.01), an increase which was more pronounced in hypertriglyceridemic patients. Furthermore, the subfraction high-density lipoprotein-2 mass was significantly lower in uremic patients compared with controls. Finally, no significant differences in the lag time, the rate of oxidation and the relative electrophoretic mobility values in each LDL subfraction between the two groups were observed. We conclude that uremic patients with heavy proteinuria exhibit compositional lipoprotein changes that are less marked than those observed in nonuremic patients with nephrotic syndrome. However, there is no evidence that circulating LDL isolated from these patients is more susceptible to oxidation in vitro than lipoprotein isolated from age- and gender-matched controls.
    Nephron Clinical Practice 01/2003; 95(3):c77-83. · 1.65 Impact Factor
  • Atherosclerosis Supplements - ATHEROSCLER SUPPL. 01/2003; 4(2):336-336.
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    ABSTRACT: The autosomal dominant form of polycystic kidney disease is a very frequent genetically heterogeneous inherited condition affecting approximately 1 : 1000 individuals of the Caucasian population. The main symptom is the formation of fluid-filled cysts in the kidneys, which grow progressively in size and number with age, and leading to end-stage renal failure in approximately 50% of patients by age 60. About 85% of cases are caused by mutations in the PKD1 gene on chromosome 16p13.3, which encodes for polycystin-1, a membranous glycoprotein with 4302 amino acids and multiple domains. Mutation detection is still a challenge owing to various sequence characteristics that prevent easy PCR amplification and sequencing. Here we attempted a systematic screening of part of the duplicated region of the gene in a large cohort of 53 Hellenic families with the use of single-strand conformation polymorphism analysis of exons 16-34. Our analysis revealed eight most probably disease causing mutations, five deletions and three single amino acid substitutions, in the REJ domain of the protein. In one family, a 3-bp and an 8-bp deletion in exons 20 and 21 respectively, were co-inherited on the same PKD1 chromosome, causing disease in the mother and three sons. Interestingly we did not find any termination codon defects, so common in the unique part of the PKD1 gene. In the same cohort we identified 11 polymorphic sequence variants, four of which resulted in amino acid variations. This supports the notion that the PKD1 gene may be prone to mutagenesis, justifying the relatively high prevalence of polycystic kidney disease.
    European Journal of HumanGenetics 10/2001; 9(9):677-84. · 4.32 Impact Factor
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    K Siamopoulos
    Nephrology Dialysis Transplantation 02/2001; 16 Suppl 6:46-7. · 3.37 Impact Factor
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    ABSTRACT: To determine the maximum-tolerated dose (MTD), the principal toxicities, and the pharmacokinetics of 6-hour infusion of glufosfamide (beta-D-glucosylisophosphoramide mustard; D-19575), a novel alkylating agent with the potential to target the glucose transporter system. Twenty-one patients (10 women and 11 men; median age, 56 years) with refractory solid tumors were treated with doses ranging from 800 to 6,000 mg/m(2). Glufosfamide was administered every 3 weeks as a two-step (fast/slow) intravenous infusion over a 6-hour period. All patients underwent pharmacokinetic sampling at the first course. The MTD was 6,000 mg/m(2). At this dose, two of six patients developed a reversible, dose-limiting renal tubular acidosis and a slight increase in serum creatinine the week after the second and third courses of treatment, respectively, whereas three of six patients experienced short-lived grade 4 neutropenia/leukopenia. Other side effects were generally mild. Pharmacokinetics indicated linearity of area under the time-versus-concentration curve against dose over the dose range studied and a short elimination half-life. There was clear evidence of antitumor activity, with a long-lasting complete response of an advanced pancreatic adenocarcinoma and minor tumor shrinkage of two refractory colon carcinomas and one heavily pretreated breast cancer. The principal toxicity of 6-hour infusion of glufosfamide is reversible renal tubular acidosis, the MTD is 6,000 mg/m(2), and the recommended phase II dose is 4, 500 mg/m(2). Close monitoring of serum potassium and creatinine levels is suggested for patients receiving glufosfamide for early detection of possible renal toxicity. Evidence of antitumor activity in resistant carcinomas warrants further clinical exploration of glufosfamide in phase II studies.
    Journal of Clinical Oncology 11/2000; 18(20):3535-44. · 18.04 Impact Factor
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    ABSTRACT: A number of adverse metabolic effects are associated with indapamide administration, including an increase in serum uric acid levels. It has been reported that losartan can significantly decrease serum uric acid levels. However, there are no data on the effects of combination therapy of losartan with indapamide on uric acid metabolism. We studied 20 hypertensive patients in whom serum metabolic parameters, including uric acid levels in serum and urine, were studied before and after eight weeks of indapamide administration (2.5 mg once daily) as well as eight weeks after combination treatment with indapamide (2.5 mg once daily)and losartan (50 mg/day). Indapamide evoked a significant decrease in systolic and diastolic blood pressure from a mean value of 157 +/- 12 mmHg/96 +/- 10 mmHg to a mean value of 139 +/- 14 mmHg/92 +/- 5 mmHg (p<0.01 for both comparisons). However, a significant increase in serum uric acid levels was noticed after indapamide administration (from a mean value of 4.9 +/- 1.6 mg/dl to a mean value of 5.9 +/- 1.2 mg/dl, p<0.01), associated with a decrease in the fractional excretion of uric acid(from a mean value of 9 +/- 5% to a mean value of 7 +/- 5.5%, p<0.05). The addition of losartan caused a further decrease in blood pressure from a mean value of 139 +/- 14 mmHg/92 +/- 5 mmHg to a mean value of 120 +/- 15 mmHg/84 +/- 4 mmHg (p<0.01 for both comparisons). This was followed by a significant decrease in serum uric acid levels to 5 +/- 1.1 mg/dl(p<0.01) due to a substantial increase in fractional urate excretion (from 7 +/- 5.5 to 8.7 +/- 6%, p<0.05). The addition of losartan could offset the hyperuricaemic effect of indapamide administration.
    Journal of Renin-Angiotensin-Aldosterone System 09/2000; 1(3):289-91. · 2.29 Impact Factor
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    M Elisaf, E Rizos, K Siamopoulos
    QJM: monthly journal of the Association of Physicians 06/2000; 93(5):318-9. · 2.36 Impact Factor
  • Atherosclerosis 01/2000; 151(1):305-305. · 3.71 Impact Factor
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    ABSTRACT: Serum aluminum levels were determined by instrumental neutron activation analysis in 31 patients undergoing long-term haemodialysis. Aluminum-28 1.778 MeV (T 1/2=2.24 min) γ-rays produced by the thermal neutron reaction27Al(n,γ)28Al were detected. Successive irradiation of the samples at epithermal neutron fluence was performed to correct for the interference from the fast neutron reaction31P(n,α)28Al. Serum aluminum level in this group of subjects was adequately represented by a lognormal distribution with a mean and variance of 16.5 μg/l and 16.8 μg/l, respectively. The results obtained were found to be in agreement with serum aluminum determination performed by electrothermal atomic absorption spectrophotometry (r 2=0.97). Instrumental neutron activation can provide a rapid technique to routinely monitor long-term haemodialysis patients in order to identify individuals at greater risk to develop aluminum toxicity.
    Journal of Radioanalytical and Nuclear Chemistry 08/1999; 241(3):483-486. · 1.47 Impact Factor
  • M Elisaf, A Tselepis, K Siamopoulos
    Clinical Chemistry and Laboratory Medicine 03/1999; 37(2):165. · 3.01 Impact Factor
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    ABSTRACT: It has recently been suggested that increased lipoprotein (a) levels are an independent risk factor for coronary heart disease. It has also been reported that tamoxifen can induce changes in blood lipid values. In this prospective study we investigated the long term effects tamoxifen on the lipid profile, focusing on lipoprotein (a) levels. Thirty-eight postmenopausal women with breast cancer treated with tamoxifen at a dose of 20 mg daily were studied. The mean age was 61 years. Serum lipoprotein (a) levels and lipid parameters (total cholesterol, high and low density lipoprotein cholesterol, triglycerides, apolipoprotein A-I and B) were measured after an overnight fast on the 1, 3, 6 and 9 month of tamoxifen treatment. A progressive fall in median lipoprotein(a) levels from 8 mg/dl to 3 mg/dl (p < 0.001) was observed. In addition, a significant decrease in the total and low density lipoprotein cholesterol and in apolipoprotein B, as well as an increase in apolipoprotein A-l were also noticed. It is concluded that our data on serum lipoprotein(a) levels agree with the beneficial anti-atherogenic effects of tamoxifen administration on lipoproteins.
    Anticancer research 01/1996; 16(5A):2725-8. · 1.71 Impact Factor