Biomedical subjects

G Koliakos

Publications and source records attributed to G Koliakos.

5 recordsLinked to original sources

PubMed1995

Increased lung uptake during myocardial scintigraphy improves the detection and localization of coronary artery disease.

Increased lung uptake during exercise thallium 201 scanning denotes severe ventricular hypofunction. To assess whether there is any relationship between this finding and the stenosis of a single coronary artery, the authors studied 140 patients (age 57.5 +/- 12 years) with both exercise thallium and coronary angiography within three months. A planar view was acquired for two hundred forty seconds immediately postexercise and prior to the single photon emission computed tomography acquisition. Two identical regions of interest outlining the left ventricle and the right lung in the planar view were used for calculation of the lung uptake, expressed as a lung-to-heart counts ratio. The patients were divided into four angiographic groups: (I) lesions at the left anterior descending (LAD), n = 35; (II) stenosis at the circumflex (CRX), n = 35; (III) stenosis at the right coronary artery (RCA), n = 35; and (IV) another group of 35 normal subjects serving as controls. No patient had a previous myocardial infraction (MI) or any cardiac operation. Patients in groups I (0.53 +/- 0.094) and II (0.44 +/- 0.072) had higher lung uptake than those in groups III (0.43 +/- 0.061) or IV (0.42 +/- 0.050). There was no difference between groups III and IV, or II and IV, but the difference between I and IV was of statistical significance (P < 0.001).(ABSTRACT TRUNCATED AT 250 WORDS)

Aged↗

PubMed1992

Effect of pyridoxine deficiency on immunological phenomena.

Measurements of serine hydroxymethyltransferase (SHMT) in resting lymphocyte cultures showed that the level of activity of this enzyme was very low. Under the influence of mitogenic stimuli serine hydroxymethyl-transferase activity was induced 5-20-fold. Addition in the cultures of 4-deoxypyridoxine, a potent antagonist of vitamin B6 coenzymes, concurrently with the mitogen, inhibits the induction of serine hydroxymethyltransferase. Thus deoxypyridoxine exerts its effects not only at the level of the enzyme itself by antagonizing the coenzyme but also at the level of its biosynthesis. Synchronous addition of vitamin B6 with deoxypyridoxine effectively reverses the inhibitory effects. The T helper cells of the lymphocyte culture are very sensitive to deoxypyridoxine action in contrast to T suppressor cells. The effect of phytohaemagglutinin or concanavalin A on the production of interleukin-1b, interleukin-2 and interleukin-2 receptors is profoundly affected by deoxypyridoxine. These results give a deeper insight of the mechanisms by which pyridoxine deficiency causes significant reduction of humoral and cellular immune responses to antigenic stimuli. On the basis of the data of this report a detailed illustration of the events that follow the T cell activation is presented. From this investigation the enzyme serine hydroxymethyltransferase emerges as a key element in the processes of immune responses and cell proliferation. Based on this finding we advance the following two propositions for possible future medical application: (i) combination of deoxypyridoxine with immunosuppressive drugs in case of immunosuppressive therapy or organ transplantation. (ii) the enzyme presents an excellent target for chemotherapy and therefore development of special agents directed against its apoprotein may prove to be a very valuable medical tool.

Antibody Formation↗

PubMed1989

Total body haematocrit iron kinetics and erythrocyte life span in pigeons (Columba livia).

1. The mean pigeon erythrocyte life span was found to be 17-25 days by Cr51-labeled erythrocytes and 21 +/- 3.4 days by iron kinetics. 2. Total red blood cell volume has been calculated by Cr51-labeled erythrocytes while total plasma volume was determined both by a dye method and iron kinetic data. From these results total blood volume and total body haematocrit were found to be 0.090 +/- 0.002 ml/g body wt and 36 +/- 4.3%, respectively. 3. Venous haematocrit, haemoglobin concentration, erythrocyte count, mean corpuscular haemoglobin concentration, plasma iron and red blood cell iron have also been measured. 4. A significant difference between total body and venous haematocrit and a short mean red blood cell life span, due to ageing and to random destruction of erythrocytes were shown. 5. The above observations are compared with analogous available data for human beings and their physiological significance is discussed.

Animals↗

PubMed1989

A new glucose 6-phosphate dehydrogenase variant (G6PD Thessaloniki) in a patient with idiopathic myelofibrosis.

A new deficient glucose 6-phosphate dehydrogenase (G6PD) variant, G6PD Thessaloniki, which was found in the red blood cells of a 70-year-old woman who had idiopathic myelofibrosis, is described. G6PD Thessaloniki had a low Michaelis constant (Km) for G6P (20 microM), high Km for NADP (10.1 microM), normal pH optimum, reduced heat stability, decreased electrophoretic mobility (96-98% of the normal), increased 2-deoxy-G6P and decreased galactose 6-phosphate utilization. Several other enzymatic activities measured in the patient's red blood cells were normal. Studies of red blood cell survival and glucose utilization gave evidence of haemolysis caused by defective glucose utilization by the pentose phosphate pathway. The only son of the patient had normal G6PD in his red blood cells. In an attempt to investigate the origin of G6PD Thessaloniki, heat stability tests of G6PD extracted from the patient's skin have been performed.

Aged↗

PubMed1988

C3 complement types in northern Greece.

The C3 complement types were studied in 463 patients with thyroid diseases and in 211 controls. There were no significant differences with respect to gene or phenotype frequencies between patient groups and controls. In the total sample, the gene frequencies are similar to those found in other European populations.

Adult↗