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Biomedical subjects

A Tourkantonis

Publications and source records attributed to A Tourkantonis.

At least 55 records · Page 3Linked to original sources
PubMed1992

Evaluation of [14C]aminopyrine breath test, peripheral clearance of [99mTc]EHIDA, and serum bile acid levels in liver function and disease.

The purpose of this study is to evaluate the diagnostic value of the following tests in the assessment of patients with chronic liver disease (CLD) and cholestatic syndrome (CS): (1) aminopyrine breath test, measuring 14CO2 excretion in the expired air, (2) peripheral clearance of [99mTc]EHIDA, and (3) postprandial levels of glycocholic acid (GCA) and glycochenodeoxycholic acid (GCDCA). The results indicate that: (1) 14CO2 2-hr excretion rate is a specific and sensitive marker of liver function, with good correlation with postprandial bile acid levels, [99mTc]EHIDA retention, and the conventional tests of serum albumin and prothrombin time. (2) Peripheral clearance and retention of [99mTc]EHIDA increased in both groups of CLD and CS vs controls, but it does not discriminate between the two. (3) Postprandial bile acids were elevated in CLD, particularly those of GCDCA, whereas GCA levels were significantly elevated in CS compared with CLD. This may be due to increased synthesis and entry into the blood. (4) The combination of [14C]aminopyrine breath test and postprandial levels of GCDCA enhance the diagnostic value, specificity, and sensitivity in the assessment of patients with CLD.

Adult↗
PubMed1992

Reduction of CyA nephrotoxicity by nifedipine during and after experimental in situ renal preservation.

In order to evaluate the role of nifedipine in the nephrotoxic effect induced by both ischemia and CyA, 18 healthy mongrel dogs were used. The kidneys were exposed and subjected to 1 h of ischemia by clamping both renal vessels. To the renal artery of the first group of kidneys (n = 9), 300 mL of cold Euro-Collins solution, in which nifedipine (Bay a 1040-10 mg) was diluted, was infused for 15 min (nifedipine group), while 300 mL of cold Euro-Collins solution plus 10 mg of placebo (Bay a 1040-placebo) was infused to the renal artery of the second group (n = 9) of kidneys (placebo group). Venous drainage was effected through a plastic cannula. All animals received through a nasogastric catheter 20 mg/kg cyclosporine A at the beginning of the ischemia. The 1 h of ischemia was divided in a 15-min period of cold ischemia and 45-min of warm ischemia, at the end of which the clamps were removed. During the 2 h (30 min x 4) after reperfusion, 10 mg of nifedipine and placebo was administered additionally by a peripheral vein to the nifedipine and the placebo group, respectively. Then the kidneys were removed for histological study. Urine volume and creatinine and urea clearances of the nifedipine group were significantly higher than the placebo group (p < 0.001) while TxB2 levels were higher in the placebo group in all studied periods (p < 0.001). Urine sodium, FENa, osmolar clearance, and LDH values were significantly different (p < 0.01), but the urine potassium concentration was not different in the two groups.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1992

Acute cyclosporin A renal dysfunction in dogs reversed by calcium antagonists and antiplatelet agents.

The aim of this study was to assess the effect of nifedipine and piracetam alone or in combination in the protection of renal function and morphology after cyclosporin A (CyA) administration. Thirty healthy mongrel dogs with a mean body weight of 15 kg were sacrificed. Six animals (group C) were given CyA 20 mg/kg body weight per os, while the remaining groups (8 animals each) were given concomitantly 20 mg nifedipine (group CN) or 4 g of piracetam (group CP), or both drugs in combination (group CNP). After 5 days of drug administration the animals were anesthetized, both kidneys were exposed, and functional tests were performed. Then the kidneys were removed for histological study. The mean plasma CyA levels in the four groups were 1765 +/- 685 ng/mL, 1300 +/- 324 ng/mL, 1116 +/- 491 ng/mL and 1600 +/- 290 ng/mL, respectively. Urine volume, creatinine, urea, and osmolar clearances were significantly higher in the groups CN, CP, and CNP compared to the control group C (p < 0.01). Urine sodium concentration was significantly higher (p < 0.05 or p < 0.01) in nifedipine groups than in the other two groups of animals, while the fractional excretion of sodium (FENa%) was significantly higher (p < 0.01) in all treated groups compared to controls. Plasma thromboxane-B2 levels were significantly reduced by each drug alone or in combination (p < 0.01). Morphological lesions, similar in all groups, did not correlate with the functional improvement.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1992

Influenza vaccination in chronic hemodialysis patients. The effect of zinc supplementation.

Since influenza increases the mortality of chronically ill patients we decided to study the effectiveness of influenza vaccination in hemodialysis (HD) patients. Nineteen HD patients aged from 20 to 60 years, on unrestricted diet and with no febrile episode, were studied. Blood samples were collected before the intramuscular injection of 0.5 mL multivalent influenza vaccine (Inflexal Berna) and every 2 weeks thereafter. At the end of 4th week a second vaccination was done and a dosage of 200 mg of zinc acetate (60 mg elemental zinc) was given daily to each patient for at least 4 weeks. Before vaccination the antibody titers to influenza virus ranged from 1:10 to 1:80 and after vaccination from 1:20 to 1:640. Four weeks after vaccination 6/19 (31.5%), 8/19 (42%), and 10/19 (52.5%) patients showed a fourfold or greater increase at serum antibody titers to antigens A/Singapore, A/Sichuan, and B/Beijing, respectively. The zinc supplementation after the second vaccination induced a similar increase of serum antibody titers to the A/Singapore but some even greater increase of the antibody titers to the A/Sichuan and B/Beijing. Serum immunoglobulins and complement components C3/C4 were not changed during this study. It is suggested that about 50% of uremic patients respond to the influenza vaccination and that zinc treatment does not increase this responsiveness.

Adult↗
PubMed1992

The impact of early or late diagnosis on patient survival in gastric cancer in Greece.

The purpose of this study was to investigate the reasons for delayed diagnosis of gastric cancer in the Greek population and correlate survival with early or late diagnosis. We studied 100 patients with gastric cancer proven at endoscopy. Early diagnosis (less than 3 months from the onset of symptoms) was established in 28 patients (28%), while the diagnosis was late (greater than 3 months) in 72 patients (72%). The reasons for late diagnosis were: 1. delayed consultation on the part of the patient, 2. incorrect medical diagnosis at a) initial evaluation, b) radiological evaluation and, as a result, c) failure to refer for endoscopy and biopsy. Patient survival correlated well with tumor resectability, irrespective of early or late diagnosis. In patients with early diagnosis and resectable tumor survival was 9.9 +/- 4.8 months (mean +/- SD) whereas with non-resectable tumor 4.8 +/- 4.0 months (p less than 0.01). In patients with late diagnosis, survival in resectable tumor was 13.5 +/- 11.7 months compared with 8.5 +/- 6.9 months in non-resectable tumor. No correlation was noted between survival and anatomic location of tumor or degree of histologic differentiation. Early diagnosis of gastric cancer is associated with a higher degree of resectability and therefore of better survival.

Adult↗
PubMed1991

Single-dose pefloxacin pharmacokinetics and metabolism in patients undergoing continuous ambulatory peritoneal dialysis (CAPD).

Seven adult patients on continuous ambulatory peritoneal dialysis (CAPD) received one dose of pefloxacin, a novel quinolone antibiotic, orally and intravenously on two separate occasions to characterize the pharmacokinetics and metabolism of the drug. Concentrations of both pefloxacin and its active metabolite N-desmethyl-pefloxacin (norfloxacin) were measured in serum and dialysate by HPLC. Half-life, total body clearance and peritoneal clearance were determined. The overall elimination half-life was 19.9h. Relative to the IV dose the bioavailability following oral administration of pefloxacin was 76%. The mean serum and dialysate concentrations were similar up to 24 h after the oral or IV dose. After a 6-h dwell time the dialysate concentration of pefloxacin was 2.24 mg/L which is above the MIC90 for most bacteria responsible for peritonitis in CAPD patients. The peritoneal clearance of pefloxacin averaged 2.5 mL/min. Serum concentrations of the metabolite norfloxacin were less than 0.5 mg/L during the 24 h study period. We conclude that pefloxacin might be equally effective in the treatment of peritonitis of CAPD after oral or IV administration. Since the peritoneal clearance contributes insignificantly to the elimination of pefloxacin during CAPD, the proposed maintenance regimen of an oral or IV 400 mg dose/day seems to be a reasonable therapy for infections in CAPD patients.

Administration, Oral↗
PubMed1990

Induction chemotherapy with a new regimen alternating cisplatin, fluorouracil with mitomycin, hydroxyurea and bleomycin in carcinomas of nasopharynx or other sites of the head and neck region.

Sixty-six patients with locally advanced (Stages III and IV) carcinoma of the head and neck were treated with three cycles of induction chemotherapy, consisting of cisplatin, fluorouracil (FU) infusion, bleomycin, mitomycin, and hydroxyurea, followed by radiotherapy and/or surgery. There were 48 men and 18 women with a median age of 55 years (range, 18 to 75 years) and Karnofsky performance status of 80 (range, 40 to 90). Primary site was nasopharynx (28 patients), followed by larynx (12) and others (26). Forty-one (62%) patients were presented with Stage IV disease. The response rate to induction chemotherapy was 27% complete response, 50% partial response, 20% stable disease, and 3% progressive disease. There was no significant difference in response rate between patients with cancer of nasopharynx or other sites (P greater than 0.1). Survival was 61% at 24 months. Patients with cancer of nasopharynx had a better survival than those with other primaries (P = 0.033). Toxicities from chemotherapy included alopecia (73%), nausea/vomiting (66%), leukopenia (54%), stomatitis (36%), anemia (32%), thrombocytopenia (16%), and diarrhea (9%). Grade IV toxicity was not observed. Induction chemotherapy with this new regimen resulted in a high response rate but may not be superior to cisplatin and FU alone. It can be safely combined with radiotherapy as a potentially curative therapy in squamous cell carcinoma of the head and neck. Chemotherapy followed by radiation therapy may yield survival similar to radical surgery in laryngeal and other head and neck cancers.

Adult↗
PubMed1989

A pilot study of piracetam in cuprophan hemodialysis.

Twelve patients, 8 male and 4 female, aged from 26 to 70 years were studied. They were on hemodialysis (HD) 4 h three times weekly with cuprophan hollow fiber dialyzers (Gambro 120M) and dialysate containing 35 mEq/L of acetate. The study compares two random HD sessions on each patient. Sixty minutes prior to one random session a placebo was administered orally, and prior to another random session piracetam was given at a dose of 8 g. Heparin dosage was not reduced during HD using QB 200 ml, QD 500 ml, and no ultrafiltration. Blood samples for leukocyte and platelet counts, serum C3, arterial paO2 and paCO2, thromboxane-B2 (TxB2), and beta-thromboglobulin (beta-TG) were taken from the arterial line before and at 15, 60, and 240 min during HD. Leukopenia at 15 min of HD was found to be less severe (p less than 0.01) in the piracetam study than in the placebo, whereas platelet count did not change. Serum C3 was slightly increased in both studies. Arterial oxygen was preserved close to the initial levels by piracetam (91.66 mm Hg versus 81.08, p less than 0.01 at 60 min, and 93.08 versus 80.17 mm Hg, p less than 0.01 at 240 min of HD sessions) but paCO2 did not change significantly. TxB2 increased less with piracetam in comparison to placebo (p less than 0.01 or p less than 0.001), but beta-TG was reduced significantly by piracetam at any time during HD (p less than 0.001).(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1989

Effect of prostaglandin E2 (PGE2) in the prevention of acute renal failure in anesthetized dogs. In situ renal preservation.

Six healthy dogs, after control measurements, were subjected to renal artery occlusion for 90 min, under general anesthesia. 5 mg of PGE2 (Prostin E2, Upjohn) diluted in 100 mL of normal saline was infused directly into the left renal artery for 90 min (PG group), while only normal saline was infused into the right renal artery (control group). After removal of the clamps blood and urine samples were collected every hour for the first 3 h of revascularization and both kidneys were then removed for histological study by light microscopy. PG kidneys regained urine flow above the oliguric levels within 3 hr of revascularization (0.30 +/- 0.04 mL/min vs 0.14 +/- 0.03 mL/min in controls (p less than 0.001). Creatinine, urea, and osmolar clearances were also significantly higher in PG group (p less than 0.01 or p less than 0.001 for 2 and 3 hr of follow-up after revascularization). Urine sodium concentration and fractional sodium excretion (FENa) (%) were not significantly lower in the PG group compared to the controls. Histology showed focal brushborder loss, hyaline and granular casts, focal tubular dilation, and focal necrotic lesions on the tubular cells in both groups of kidneys. A direct cytoprotective effect of the PGE2 was not found. It is suggested that PGE2 is effective in the protection of renal function when it is administered during the mechanical occlusion model of acute renal failure in anesthetized dogs.

Acute Kidney Injury↗
PubMed1989

Pharmacokinetics of aztreonam administered i.p. in continuous ambulatory peritoneal dialysis (CAPD) patients.

The pharmacokinetics of Aztreonam (AZT) administered i.p. in six stable patients undergoing continuous ambulatory peritoneal dialysis (CAPD) for end-stage renal disease (ESRD) were studied. One gram of AZT was added into a 2 L bag of dialysate (Medital-Bieffe) just prior to infusion into the peritoneal cavity. The dwell time was 8 h. The serum maximum concentration of AZT was 42.5 +/- 12.4 mg/L (mean +/- SD), achieved in 4.6 +/- 1.0 h. The elimination half-life was 2.4 +/- 0.8 h, almost equal to that found in normal subjects (1.7-2 h). The pharmacokinetic parameters of elimination, as elimination rate constant and clearance of AZT from peritoneal cavity were found 0.305 +/- 0.101 h-1 and 10.05 +/- 3.7 mL/min, respectively, while the bioavailability via the peritoneal membrane was 90.8 +/- 3.05% of administered dose. It is concluded that AZT is eliminated from dialysate at a high rate after i.p. administration and its dialysate and serum levels exceed the MIC for the majority of sensitive organisms including Pseudomonas species. Aztreonam appears to be a potentially useful antibiotic for CAPD peritonitis.

Adult↗
PubMed1988

[Combined therapy of locally advanced squamous epithelial cancers in the area of the head and neck].

In an effort to improve treatment results in locally advanced squamous cell carcinoma of head and neck, we designed a multimodality treatment programme consisting of three cycles of inductive chemotherapy, after 2-3 weeks loco-regional therapy (surgery and/or radiotherapy), two more cycles of adjuvant chemotherapy with the same regimen were given finally. The chemotherapeutic regimen included cis-platinum 100 mg/m2 on day 1, 5-fluorouracil 100 mg/m2 on days 2-6 as a continuous infusion, bleomycin 15 units on days 15, 29; mitomycin-C 4 mg/m2 on day 2 and hydroxyurea 100 mg/m2 on days 22-26. From August 1984 onwards, 37 patients entered in this study. The group included 31 men and 6 women with a medium age of 54 (18-71) and a performance status of 80 (60-90). Primary sites were nasopharynx (13), oropharynx (5), hypopharynx (3), sinus (3), ethmoids (2), tongue (2), floor of the mouth (2), larynx (6) and unknown (1). 25 patients received 3 cycles of induction therapy whereas 22 completed the whole treatment programme. Following induction therapy, 28% of the patients demonstrated histologically confirmed CR, 40% PR and 32% SD, while after the full multimodality therapy 59% demonstrated CR, 36% PR and 5% SD. Follow-up is 9-36 months. Actual survival at 3 years is 80% for those with a CR post loco-regional therapy. Toxicities were leukopenia (40%), thrombocytopenia (20%), anaemia (40%), nausea and vomiting (60%), stomatitis (52%) diarrhoea (16%) and alopecia (79%). There was one death related to chemotherapy.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗
PubMed1988

Small intestinal function and structure in patients with chronic renal failure.

We studied 24 patients with end-stage chronic renal failure not treated with hemodialysis (CRF1) and 16 patients on regular hemodialysis (CRF2), to investigate the digestive, absorptive and morphological aspects of the small intestinal mucosa. Serum d-xylose test and biochemical parameters of absorption (serum calcium and proteins) were determined. Jejunal mucosal biopsies were obtained and tissue homogenates assayed for disaccharidases (sucrase, maltase and lactase) and dipeptidases (glycyl-glycinase, leucyl-glycinase and leucyl-aminopeptidase). Histological changes were classified according to the severity of abnormality and compared with biopsies obtained from control subjects. Serum d-xylose test, calcium and proteins were normal in patients with CRF. Maltase specific activity was higher in CRF1 than in controls (p less than 0.05). Lactase and leucyl-aminopeptidase showed a tendency to decrease in CRF, but this difference did not reach statistical significance. Sucrase, glycyl-glycinase and leucyl-glycinase specific activity in CRF was similar to the control group. Histological changes of the small intestinal mucosa of mild to moderate degree were noted in 68% of patients with CRF vs 36% in control subjects (p less than 0.01). No significant difference was noted in the incidence of absorptive, enzymatic (with the exception of maltase) and histological changes between the two groups of patients with CRF. These changes are not influenced by hemodialysis, a long-term treatment averaging 6 months, they appear to represent primary manifestations of CRF and may be related to the nutritional status of patients with CRF.

Adult↗