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Biomedical subjects

G Papageorgiou

Publications and source records attributed to G Papageorgiou.

At least 37 records · Page 2Linked to original sources
PubMed1988

Ovarian stimulation for in-vitro fertilization combining administration of gonadotrophins and blockade of the pituitary with D-Trp6-LHRH microcapsules: pilot studies with two protocols.

In women undergoing in-vitro fertilization and embryo transfer (IVF-ET), a total of 408 IVF cycles were stimulated using human menopausal gonadotrophin (HMG) or pure follicle stimulating hormone (FSH) plus HMG in combination with a single injection of D-Trp6-LHRH microcapsules in order to enhance the ovarian response to gonadotrophins and to avoid spontaneous LH surges. Sixty-seven pregnancies were achieved. Two protocols were employed. In protocol 1 ('blocking protocol', n = 268), the pituitary was first inhibited with a full dose (3.75 mg) of D-Trp6-LHRH in microcapsules and ovarian stimulation was started after the hypogonadotrophic hypogonadal state was ascertained (E2 less than 50 pg/ml). In protocol 2 ('flare-up protocol', n = 140), the treatment with D-Trp6-LHRH microcapsules (half-dose = 1.80 mg) and the ovarian stimulation with gonadotrophins were started at the same time. Higher doses of gonadotrophins were needed (39.5 +/- 11.2 ampoules FSH and/or HMG) in protocol 1, in which the pituitary was blocked prior to and during the stimulation, than in protocol 2 (20 +/- 9 ampoules) where the exogenous gonadotrophin stimulation appeared to be augmented by the initial agonistic effect of the injection of D-Trp6-LHRH microcapsules. In patients with purely tubal infertility, under 38 years old and no male factor, the results obtained with protocols 1 and 2 were similar in terms of pregnancy rate per cycle or per embryo transfer: 22.6 versus 20.5% and 28.3 versus 27.4%, respectively. However, considering the cost benefit, 'flare-up' protocols appeared to be a better choice and could be recommended.

Adult↗
PubMed1985

Hemipelvectomy for neoplasms not originating in the pelvis.

10 patients underwent hemipelvectomy, mainly for sarcomas originating high in the thigh, or melanomas and epidermoid carcinomas metastatic to the groin. 1 patient died postoperatively, 3 lived 5-12 years and 1 died of unrelated cause 2 years after the operation, all free of recurrence. Tumors treated successfully were large and with indolent locoregional growth, often despite repeated unsuccessful local treatment attempts. These tumor characteristics should be considered as favorable features, in selecting such patients for hemipelvectomy. Conversely 3 patients with melanoma had short history before and died soon after the operation, contraindicating hemipelvectomy in locally advanced melanoma.

Adult↗
PubMed1984

The DNase activity of an endoplasmic reticulum nuclease and its effect on DNA synthesis in vitro.

An endoplasmic reticulum nuclease which was isolated previously in this laboratory from rat liver ( Kouidou et al. (1981) Eur.J. Bioch . 120, 9-14) was found to degrade linear and circular single stranded DNA but not double stranded DNA. The DNA fragments resulting from this cleavage were longer than 20 nucleotides. In addition the nuclease was found to improve the efficiency of DNA template used by DNA polymerase I in DNA synthesis in vitro. The results were the same whether incubation of the template with the nuclease was prior to addition of DNA polymerase I or simultaneously with polymerization. When nuclease was added after the completion of polymerization by DNA polymerase I it was ineffective unless the product was denatured. These data further corroborate the observation that double stranded DNA is not cleaved by this enzyme.

Animals↗
PubMed1983

Pre- and postoperative chemoendocrine treatment with or without postoperative radiotherapy for locally advanced breast cancer.

From July, 1978 to September, 1981, 184 patients with localy advanced breast cancer (T3; T4a-b; any N; M0) regardless of their hormonal receptor status, entered a trial to evaluate the contribution of radiotherapy when added to an intensive preoperative chemoendocrine regimen. Seventy-eight patients were ultimately disqualified. All patients underwent sequentially: (1) two cycles of chemotherapy: Day 1--Oncovin 1.4 mg/m2, cyclophosphamide 350 mg/m2, Adriamycin 30 mg/m2; Day 2--methotrexate 20 mg/m2, 5-fluorouracil 350 mg/m2 (in addition, antiestrogens were given to postmenopausal patients); (2) mastectomy with complete axillary dissection combined with oophorectomy in patients before and one year after menopause; (3) radiotherapy randomly to one-half of the patients; and (4) ten additional chemotherapy cycles as above, with antiestrogens to all patients. No serious local sequellae were encountered from mastectomy or radiotherapy, but complications of chemotherapy were numerous, particularly in irradiated patients. One death due to toxicity occurred after preoperative chemotherapy. The results to date suggest that in irradiated patients metastases may become enhanced and that their local disease is not more effectively controlled than in patients not having radiotherapy. Two factors may have been largely responsible for the differences observed between the two groups: the delay of chemotherapy in irradiated patients and the sustained immunosuppression known to occur after mediastinal radiotherapy.

Aged↗
PubMed1975

Quenching of excited chlorophyll A in vivo by nitrobenzene.

Nitrobenzene exerts a dual effect on the excitation of chlorophyll a(Chl a) in vivo. (a) A 3(3,4-dichlorophenyl)-1,1-dimethylurea-inhibited quenching that manifests as a partial inhibition of variable chloroplast fluorescence and of 2,6-dichlorophenol indophenol (DCPIP) photoreduction and saturates at ca. 5-10 muM. Since nitrobenzene is not a Hill oxidant, this effect is attributed to a catalyzed back flow of electrons from intersystem intermediates to pre-photosystem II oxidants. (b) A direct quenching of the excited Chl a in vivo. This effect has a threshold of ca. 100 muM nitrobenzene; at higher concentrations it leads to almost complete suppression of chloroplast fluorescence and DCPIP photoreduction. Tris-washed chloroplast enriched in the photosystem II reaction center species Z+Q- and ZQ- are nearly four times more sensitive to nitrobenzene quenching than those enriched in Z+Q. On the other hand, normal chloroplasts are about 10 to the fourth times more sensitive. Hence, it is argued that the extreme sensitivity of normal chloroplast fluorescence is not due to a preferential association of nitrobenzene with a particular redox species of the reaction center.

Chlorophyll↗
PubMed1968

Light-induced changes in the fluorescence yield of chlorophyll a in vivo. I. Anacystis nidulans.

he fluorescence yield of chlorophyll a in dark adapted Anacystis nidulans undergoes a slow change with continuous illumination. After the completion of the initial fast transient, the fluorescence yield rises from the level S to a plateau M within a minute, declining only after prolonged illumination. Both normal and 1,1-dimethyl-3(3'4'-dichloro)-phenylurea (DCMU)-poisoned Anacystis are capable of these changes. In normal Anacystis, the slow increase in the fluorescence yield (S --> M) requires light absorbed in system II while light absorbed in system I is ineffective. In DCMU-poisoned Anacystis, however, these changes are also promoted by light absorbed in system I. Addition of carbonyl cyanide p-trifluoromethoxy phenylhydrazone (FCCP), a photophosphorylation uncoupler acting near the photosynthetic electron transport chain, abolishes the rise from S to M in normal but has no effect in the DCMU-poisoned system. Phlorizin, a phosphorylase inhibitor, has very little effect. These results suggest that the light-induced variation in the fluorescence yield is related to the conformational changes which accompany photophosphorylation. The fluorescence yield of the auxiliary pigment phycocyanin remains constant throughout the interval of the light-induced changes in the fluorescence yield of chlorophyll a. Consequently, the fluorescence spectrum of the alga is variable on continuous illumination.

Antimetabolites↗
PubMed1968

Light-induced changes in the fluorescence yield of chlorophyll a in vivo. II. Chlorella pyrenoidosa.

The long-term fluorescence induction in Chlorella pyrenoidosa consists of a fast rise of the fluorescence yield from the level S (of the first wave transient) to a maximum M, followed by slower decay to a terminal stationary level T. The maximum M is attained within 40 seconds from the onset of illumination while the decay to the terminal level T lasts for several minutes. The fluorescence rise (S --> M) coincides with an increase in the rate of oxygen evolution, which, however, remains constant during the fluorescence decay (M --> T). Poisons of photosynthesis 3, (3,4-dichlorophenyl)-1,1 dimethylurea (DCMU, o-phenathroline) inhibit the fluorescence induction, while uncouplers of photophosphorylation affect the fluorescence time course only when they function at an early stage of the coupling sequence e.g., carbonyl cyanide p-trifluoremethoxy phenylhydrazone, (FCCP, atabrin). Phosphorylation inhibitors affecting only the terminal esterification step (phlorizin) have little effect on the fluorescence kinetics. These results suggest that the fluorescence induction requires the operation of a phosphorylating electron transport and that it is possibly related to the light-induced structural changes which accompany photophosphorylation.

Antimetabolites↗
PubMed1967

Changes in intensity and spectral distribution of fluorescence. Effect of light treatment on normal and DCMU-poisoned Anacystis nidulans.

The intensity of the "steady-state" fluorescence of "aerobic" Anacystis nidulans is variable under prolonged illumination with orange (590 mmu) or blue (440 mmu) light for both normally photosynthesizing and DCMU-poisoned cells. In general, orange light illumination causes an increase of the fluorescence intensity followed by a decrease, while blue light causes an increase until a steady level is reached. Poisoned Anacystis cells show four to eight times larger changes in fluorescence intensity than the normal cells; the detailed time course of fluorescence changes is also different in poisoned and normal cells. When algae are cooled to -196 degrees C in light, the light-induced changes in the "steady-state" fluorescence disappear in both types of cells. Difference fluorescence spectra, constructed by subtracting the fluorescence spectra taken after 5-15 min of illumination from those after 60-90 min of illumination, show a doublet structure of the difference band with a major peak coinciding with the Anacystis emission maximum (685 mmu) and a minor peak located at about 693 mmu.

Chlorophyll↗
PubMedDate not supplied

Blockade of Kupffer cells by gadolinium chloride reduces lipid peroxidation and protects liver from ischemia/reperfusion injury.

BACKGROUND/AIMS: The implication of lipid peroxidation in the inhibitory effect of GdCl3 (gadolinium chloride) on Kupffer cells activation has not been extensively investigated. The aim of this study was to examine the effect of GdCl3 inhibition of Kupffer cells activation on lipid peroxidation after severe total hepatic ischemia/reperfusion. METHODOLOGY: Male Wistar rats (n = 40) were randomly divided into a sham-operation group, a control ischemia/reperfusion group, and two ischemia/reperfusion groups pretreated with GdCl3 (10 mg and 20 mg/kg bw intravenously, 48 and 24 h prior to operation). Following 60 min of total hepatic ischemia and 120 min of reperfusion, the rats were sacrificed, and liver samples were taken for determination of malondialdehyde and light microscopy examination. Blood samples were also taken for assay of aspartate and alanine transaminase. Additional animals (n = 60) were followed up for a 7-day survival rate determination. RESULTS: Ischemia/reperfusion decreased the survival rate to 13.3%, increased (p < 0.001) the levels of aspartate and alanine transaminase in serum to 2387 +/- 75 and 2157 +/- 87 IU/L, respectively, and increased (p < 0.001) malondialdehyde levels in liver to 1.609 +/- 0.096 nmoles/g compared with 1.164 +/- 0.060 in the sham operation group. Pretreatment with GdCl3 increased the survival rate to 60%, and decreased (p < 0.001) the levels of aspartate transaminase in serum to 1549 +/- 66 and 1496 +/- 55 IU/L, the levels of alanine transaminase in serum to 1302 +/- 48 and 1305 +/- 63 IU/L, and the levels of malondialdehyde in liver to 1.132 +/- 0.034 and 1.149 +/- 0.57 nmoles/g for the lower and the higher doses of GdCl3, respectively. Histological examination showed protection of liver parenchyma in the animals treated with GdCl3. CONCLUSIONS: Experimental data suggest that GdCl3 inhibition of Kupffer cells activation protects liver from ischemia/reperfusion injury by a mechanism that reduces lipid peroxidation.

Animals↗