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Biomedical subjects

G Politis

Publications and source records attributed to G Politis.

14 recordsLinked to original sources
PubMed1998

Trisomy 6 and double minute chromosomes in a case of chronic myelomonocytic leukemia.

A 65-year-old woman with chronic myelomonocytic leukemia was shown to have trisomy 6 and multiple double minute chromosomes. The patient had no history of prior exposure to any mutagenic or carcinogenic agents. To our knowledge, this is the first report for presence of only these two aberrations. The expression of several oncoproteins and onco-related proteins was detected immunohistochemically in bone marrow cells. Among them, only the bcl-2 oncoprotein was positively stained in 100% of myeloblasts. Although the c-myc oncogene is frequently reported to be overexpressed in myeloid disorders with double minutes and associated with chemotherapy resistance and disease aggressiveness, in our case, the c-myc oncoprotein was not positively expressed. The patient received chemotherapy and complete hematological remission was successfully achieved.

Aged↗
PubMed1993

Biological dosimetry of absorbed radiation by C-banding of interphase chromosomes in peripheral blood lymphocytes.

Induction of premature chromosome condensation enables direct observation of radiation-induced cytogenetic damage in non-stimulated, interphase, human peripheral blood lymphocytes. This phenomenon can be explored in radiation protection for biological dosimetry in instances of accidental exposure to ionizing radiation. Quantification of an exposure by means of this approach has been limited so far mainly to the analysis of chromosome fragments. This limitation is due to the fact that conventional Giemsa staining of prematurely condensed chromosomes (PCCs) does not allow visualization of the centromeric regions and, as a result, the identification of dicentrics, centric rings and acentric fragments. In the present report a C-banding procedure, refined to avoid swelling and chromosome distortion of freshly prepared PCCs spreads, is used to identify such aberrations in non-stimulated human lymphocytes. The method allows immediate banding of the centromeric regions and enables scoring of aberrations within a time interval (3-4 h after blood sample withdrawal) that is only a fraction of that normally required when cells stimulated to proliferate are analysed at metaphase. The dose-response for dicentrics and centric rings measured in interphase lymphocytes was found to be similar to that obtained at metaphase. Measurement of dicentrics and centric rings in prematurely condensed chromosomes of human lymphocytes would provide valuable information on radiation dose estimates, especially in cases of extreme urgency.

Chromosome Banding↗
PubMed1989

Effectiveness of radiation control program for Dornier HM3 lithotriptor.

Radiation exposure during extracorporeal shock-wave lithotripsy (ESWL) was calculated using a "worst-case method" in 135 randomly selected patients. The patients were divided into four groups according to body weight: small (less than 140 pounds), medium (141-180 pounds), large (181-220 pounds), and very large (greater than 220 pounds). Average skin exposure was found to be 15.2 R (from 1.2 to 95.6 R). After implementation of a "radiation awareness program" radiation exposure was calculated in 128 cases (matched for body weight and stone burden) and average exposure was 9.5 R (from 0.9 to 33.4 R) with a reduction of 20, 37, 33, and 62 percent for each group, respectively. Radiation exposure reduction was primarily due to a reduction in the number of radiographic "snapshots" taken as a result of preferential use of special-mode fluoroscopic "stills."

Body Weight↗
PubMed1988

Cholesteatoma of the renal pelvis: endoscopic management.

We report 2 cases of renal cholesteatoma, 1 of which was associated with inactive renal tuberculosis and the other with urinary stone disease. Both cases were managed by endourological techniques. The diagnosis of cholesteatoma was suspected at ureteroscopic examination of the renal pelvis and it was confirmed by histological examination of biopsy material in both cases. Treatment consisted of endoscopic extraction of the keratinous debris from the collecting system. In 1 case this was achieved with the ureteroscope and in the other case the nephroscope was used.

Adult↗
PubMed1987

Ureteroscopy in management of ureteral calculi.

Transurethral ureteroscopy (TUURS) for the management of ureteral stones was performed in 102 patients. Primary ureteroscopy was performed in 57 patients while in 20 cases the procedure was used for stone manipulation prior to ESWL and in 18 cases after ESWL treatment. In 7 cases, insertion of the instrument was impossible. The overall success rate was 89 per cent (85/95). Success rate in the lower ureter was 93 per cent, in the middle ureter 84 per cent, and in the upper ureter 80 per cent. There were four complications (4%) and open operation was required in 3 patients only (3%). The up-to-date ureteroscopic results suggest that ureteroscopy should be the procedure of choice in the treatment of lower ureteral calculi and a valuable alternative in the treatment of upper ureteral calculi.

Adult↗
PubMed1986

3-Aminobenzamide does not affect X-ray-induced cytogenetic damage in G0 human lymphocytes.

The inhibition of poly(ADP-ribose) polymerase by 3-aminobenzamide (3AB) has been reported to have very different effects on X-ray-induced chromosome aberrations in G0 human lymphocytes. One group of investigators observed a 2-3-fold increase in the yield of rings, dicentrics and chromosome breaks after X-irradiation and 3AB treatment, whereas another group found that 3AB had no effect on X-ray-induced chromosome aberrations. To resolve this discrepancy, we repeated the experiments as described by both groups and found no effect of 3 mM or 5 mM 3AB on the frequency of chromosome aberrations induced by either 1 Gy or 2 Gy of X-rays. Furthermore, we found no effect of 3AB on X-ray-induced aberration yields in C-banded prematurely condensed chromosome preparations from unstimulated human lymphocytes. These results indicate that poly(ADP-ribose) polymerase is not involved in the repair of cytogenetic damage in G0 human lymphocytes.

Animals↗
PubMedDate not supplied

Human chromosome 19 confers the CD2/E rosette receptor phenotype in interspecific cell hybrids.

Interspecific cell hybrids between Chinese Hamster Ovary (CHO) and phytohaemagglutinin (PHA) stimulated human T lymphocytes were purified by preparative rosetting with sheep red blood cells (SRBC). The hybrid cell clone used in the present study consisted of cells containing a complete set of the 20 CHO chromosomes and one extra human chromosome, No 19. Hybrid cells constitutively expressed high levels of human CD2 surface receptor and formed multilayer rosettes with SRBC and human erythrocytes. In addition to CD2 they produced low levels of a small number of human extracellular proteins. These findings suggest that the factor(s) responsible for CD2 expression are produced by the hybrid and that genes responsible for CD2 expression are located on chromosome 19. However, the present work cannot exclude that material of chromosome 1, where the CD2 gene has been assigned previously, is integrated somewhere in the hybrid karyotype. Further work is needed to clarify this point.

Animals↗
PubMedDate not supplied

Proliferation of human acute leukemia cells in culture on treatment with an homo-aza-steroid.

When cultures of human leukemia cells from 9 untreated patients with acute leukemia were treated with 3 beta-hydroxy-13 alpha-amino-13,17-seco-5 alpha-androstan-17-oic-13, 17-lactam, an increased proliferating activity was exhibited. The leukemia cells were cultured for 48h and the amounts of lactam (4, 12 and 24 ng/ml) were added at zero time in the continuous presence of (3H)-thymidine. Our data suggested that in high concentrations lactam acts as a toxic agent while in the lower ones it seems to stimulate proliferation of the blast cell.

Adult↗