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Biomedical subjects

K Virvidakis

Publications and source records attributed to K Virvidakis.

11 recordsLinked to original sources
PubMed1997

Body composition changes in chronic hemodialysis patients before and after hemodialysis as assessed by dual-energy x-ray absorptiometry.

The aim of this study was to investigate the effect of hemodialysis on body composition assessment by dual-energy x-ray absorptiometry (DEXA). Seventeen patients with chronic renal failure who were on a regular hemodialysis schedule were studied. Body weight and body composition were assessed immediately before and approximately 1 hour after a typical hemodialysis session. Body weight was assessed by means of an electronic balance. Body composition measurements were made by DEXA. Whole-body and subtotal (head and neck excluded) analysis assessed the following parameters: body weight, bone mineral density (BMD), bone mineral content (BMC), and fat (FTM) and lean (LTM) tissue mass. BMC, FTM, and LTM were estimated separately for the trunk, arms, and legs. The mean body weight reduction after hemodialysis was 2.8 +/- 1.1 kg (mean +/- SD). Concerning whole-body analysis, no change was observed in mean BMC and FTM after hemodialysis. On the contrary, a significant reduction was observed in mean body weight as assessed by DEXA (before hemodialysis, 65.0 +/- 11.4 kg; after, 62.2 +/- 10.9 kg, P = .0003), as well as in mean LTM (before hemodialysis, 42.7 +/- 9.4 kg; after, 39.7 +/- 9.0 kg, P = .0003). Similar results were obtained from subtotal and regional analysis. Body weight changes as measured by the electronic balance exhibited a strong positive correlation with the changes in both body weight and LTM as assessed by DEXA (r = .989, standard error of the estimate [SEE] = 0.167 kg and r = .941, SEE = 0.382 kg, respectively, P < .0001). It is concluded that gravimetric changes induced by hemodialysis are highly correlated with LTM changes and are not associated with changes in BMC or FTM estimated by DEXA.

Absorptiometry, Photon↗
PubMed1990

Bone mineral content of junior competitive weightlifters.

It is suggested that practicing various sports can increase the bone mineral content (BMC). However, we were unable to find any reports indicating BMC changes in weightlifting, a sport which involves both extremities and spine and increases muscle mass as well. Therefore, we thought that it might be of interest to measure BMC in junior competitive weightlifters. On the occasion of a recent Junior World Championship we measured, by single photon absorptiometry, BMC in 59 young competitive male athletes (aged 15 to 20 years) from 14 countries. Several variables were taken into account for each subject, including race, record, age, height and weight. Multiple regression analysis was performed in order to assess the contribution of the above mentioned variables to the variability of both distal and proximal BMC. Finally, athletes' BMCs were compared to matched sex and age normals. Our results suggest that junior competitive weightlifters have an increased BMC, well above the age-matched controls' mean. It seems that the vigorous exercise of weightlifters tends to fade out any race or age-related BMC differences. Finally, weightlifters' BMC seems to be highly correlated with body weight and record.

Adolescent↗
PubMed1987

Effect of doping control on weightlifting performance.

The results of participants in Junior World Championships of weight lifting were compared between the years 1978 and 1981 and also between 1981 and 1984. In contrast to a significant improvement of athletic performance which occurred between 1978 and 1981, no significant change was seen between 1981 and 1984. It is suggested that this lack of improvement may be attributed to the more effective doping control imposed in the last few years.

Anabolic Agents↗
PubMed1983

Eosinophilia in patients undergoing regular hemodialysis.

The prevalence of eosinophilia (eosinophil counts greater than 400/mm3) in 69 patients undergoing regular hemodialysis for one to 80 months was estimated as 52,2%, in a random examination. On the other hand, a retrospective chart review of 30 patients hemodialyzed at one unit between 1973 and 1981 showed that 14 of them developed either recurrent of continuous eosinophilia, while 16 never had elevated eosinophil counts over a period of 21 to 72 months. In the whole group of 30 patients, mean eosinophil count increased progressively during the first two years of hemodialysis treatment and remained unchanged thereafter. All cases of eosinophilia were observed between the years 1977 and 1981 i.e., at least two years after a change in the type of dialyzers used at this unit.

Adolescent↗
PubMed1983

Serum calcium during chemotherapy for active pulmonary tuberculosis.

Serum calcium was prospectively studied in 50 consecutive patients with active pulmonary tuberculosis. Twenty-four of them (48%) developed hypercalcaemia during an observation period of at least 8 weeks. Maximal increase in serum calcium (corrected for serum albumin) occurred three weeks after initiation of treatment, by which time 28% of the patients were hypercalcaemic. The increase in serum calcium was followed by a spontaneous remission. Only two patients developed symptoms related to hypercalcaemia, which promptly responded to steroid administration. No patient received vitamin D supplements before or during the study. No correlation could be found between hypercalcaemia and either the presence of acid-fast bacilli in the sputum or the season of the year. There was a trend for higher serum calcium values in the patients with the more severe radiographic changes on admission. Hypercalcaemia in patients with pulmonary tuberculosis seems to be triggered by chemotherapy. However, the mechanism(s) by which anti-tuberculosis treatment affects calcium metabolism remains uncertain.

Adult↗
PubMed1979

Hair zinc compared with plasma zinc in uremic patients before and during regular hemodialysis.

Plasma and hair zinc concentrations were measured by atomic absorption spectrophotometry in 34 control subjects, 20 nondialyzed uremic patients and 18 patients treated with regular hemodialysis. Plasma zinc levels were low in both nondialyzed and hemodialyzed patients. Hair zinc levels were low in the nondialyzed uremics, but at least partialy restored to normal in patients on hemodialysis. In both patient groups, hair zinc was positively correlated with plasma zinc. In the nondialyzed patients haie zinc depletion in end-stage renal disease progresses with increasing degree of renal insufficiency and tends to be reversed by regular hemodialysis.

Adult↗
PubMed1976

Relationship between degree of renal failure and impairment of intestinal calcium absorption.

The coefficient of true intestinal calcium absorption (a value) was measured by a double radioisotope technique in 29 chronic renal failure patients (serum creatinine levles 2.5-19.5 mg%) aged 20-75 years. The mean log 10 a (+/- standard error) of these subjects (1.197 +/- 0.031) was significantly lower (p less than 0.001) than that of 52 controls (1.532 +/- 0.024), the geometric mean of the renal failure group (15.7%) being approximately half (46%) of that of the controls (33.9%). The decrease of a value of the uremic patients was more pronounced in the younger than in the older subjects as shown by a statistically significant (r = 0.570; p less than 0.001) positive curvilinear, relationship between a value and age. The lowest intestinal calcium absorptions were observed in patients with a serum creatinine level of approximately 11 mg%, the a values increasing progressively with lower or larger than 11 mg% serum creatinine levels, as shown by a statistically significant (r = 0.485; p less than 0.01) parabolic relationship between a value and serum creatinine. The possible mechanism(s) of this relationship are discussed.

Adult↗
PubMedDate not supplied

The influence of varying blood and dialysate flow on haemodialysis adequacy.

The aim of this study was the exploration and correlation of the influence of variations in blood flow and dialysate flow on haemodialysis adequacy through the quantitative indexes Kt/V, TACurea and PCR. A prospective study of 48 patients subjected to haemodialysis was carried out. The collection of data included taking blood and urine samples according to the directives of DOQI, for a total of 8 months. Statistical analysis was based on the paired t-test and multiple regression analysis. The variations in blood flow and dialysate flow are positively related to the variation of the indexes Kt/V, TACurea and PCR and consequently to the haemodialysis adequacy both as isolated factors and when combined together.

Blood Flow Velocity↗