Biomedical subjects

H Carageorgiou

Publications and source records attributed to H Carageorgiou.

4 recordsLinked to original sources

PubMed2004

Regulation of gene expression via triple helical formations.

Triplex-forming oligonucleotides (TFOs) are a challenging and very promising subject in modern biochemistry and molecular genetics. Over the last decade, several studies have stated that TFOs: a) can bind to DNA in a sequence-specific manner; b) can provoke DNA repair and recombination in mammalian cells, and c) can be a very effective biological tool in embryonic and oncogenic research on gene expression pathways. Herein we review the basic modes in which TFOs exist, their gene-regulation properties, as well as the obstacles that should be overcome before they become useful in clinical practice (chemotherapy and/or gene therapy).

DNA↗

PubMed2003

Propylthiouracil-induced hypothyroidism is associated with increased tolerance of the isolated rat heart to ischaemia-reperfusion.

The present study investigated the response of the hypothyroid heart to ischaemia-reperfusion. Hypothyroidism was induced in Wistar rats by oral administration of propylthiouracil (0.05%) for 3 weeks (HYPO rats), while normal animals (NORM) served as controls. Isolated hearts from NORM and HYPO animals were perfused in Langendorff mode and subjected to zero-flow global ischaemia followed by reperfusion (I/R). Post-ischaemic recovery of left ventricular developed pressure was expressed as % of the initial value (LVDP%). Basal expression of protein kinase C epsilon (PKCepsilon) and PKCdelta and phosphorylation of p46 and p54 c-jun NH(2)-terminal kinases (JNKs) in response to I/R were assessed by Western blotting. LVDP% was found to be significantly higher in HYPO hearts than in NORM. At baseline, PKCepsilon expression was 1.4-fold more in HYPO than in NORM hearts, P<0.05, while PKCdelta was not changed. Furthermore, basal phospho-p54 and -p46 JNK levels were 2.2- and 2.6-fold more in HYPO than in NORM hearts, P<0.05. In response to I/R, in NORM hearts, phospho-p54 and -p46 JNK levels were 5.5- and 6.0-fold more as compared with the baseline values, P<0.05, while they were not significantly altered in HYPO hearts. HYPO hearts seem to display a phenotype of cardioprotection against ischaemia-reperfusion and this is associated with basal PKCepsilon overexpression and attenuated JNK activation after I/R.

Animals↗

PubMed2001

Phenylephrine induced aortic vasoconstriction is attenuated in hyperthyroid rats.

BACKGROUND: Abnormal vascular responsiveness to vasoconstrictors may play an important role in peripheral vascular resistance in hyperthyroidism. The aim of the present study was to evaluate whether the vascular response to potassium chloride and phenylephrine is abnormal in a rat model of thyroxine-induced cardiac hypertrophy. METHODS: Left ventricular hypertrophy was induced in Wistar rats by subcutaneous administration of L-thyroxine for two weeks ("THYR"), n=17. Animals treated with normal saline served as controls, ("NORM"), n=20. The thoracic aorta was dissected and cut into rings that were suspended in an isolated organ bath with Krebs-Henseleit buffer. Maximal tension, Tmax, in g was measured in response to KCl and PE at the highest concentration in rings with endothelium (+E) and without endothelium (-E) in both groups. Relaxation response (Relax percent) to acetylcholine administration was expressed as percent of the maximal tension induced by phenylephrine. RESULTS: Left ventricular weight was 0.9 (SEM, 0.04) g for THYR group vs 0.7 (0.02) g for the NORM group, p<0.05. With KCl, Tmax was not different between the THYR and NORM groups with and without endothelium. With PE, there was a difference in Tmax between THYR+E and NORM+E, 1.2 (0.05) g vs 1.5 (0.09) g, p<0.05. Tmax was also different between THYR-E and NORM-E, 1.5 (0.08) g vs 1.7 (0.07) g, p<0.05. Relax percent was not significantly different between THYR+E and NORM+E (45.9 percent vs 42.8 percent, p>0.05). CONCLUSIONS: We conclude that: a) Vascular tension of the thoracic aorta in response to PE is lower in thyroxine-treated rats as compared to controls, probably due to enhanced PE-induced vasorelaxation at high concentration. b) Relaxation response of the thoracic aorta to acetylcholine is not different between THYR and NORM groups.

Acetylcholine↗

PubMed1998

Growth and survival of Trichomonas vaginalis.

This study confirmed that Feinberg and Whittington medium was suitable for the cultivation and detailed study of the growth cycle of two clinical strains of Trichomonas vaginalis under anaerobic conditions. Both strains showed a similar growth pattern characterised by early but slow growth, extended duration of the logarithmic phase and limited survival never exceeding 144 h. Duration of survival and growth rate were inversely proportional to the inoculum density. Growth rate was pH dependent; pH values in the range 6.9-6.5 delayed the initiation of growth of T. vaginalis for at least 48 h. On the other hand, pH values of 6.4-4.5 were indifferent or slightly favourable for growth during the logarithmic and survival in the early decline phase. Normal saline and Ringer's solution exerted an early and progressively lethal effect on trichomonads and led to the disappearance of protozoa suspended in them in 150 min. In general, these in-vitro results shed light on some aspects of the biology of T. vaginalis and contribute to a better understanding of the epidemiology and clinical manifestations of the infection.

Anaerobiosis↗