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Biomedical subjects

D Constantinescu

Publications and source records attributed to D Constantinescu.

At least 19 recordsLinked to original sources
PubMed2000

B cell production and turnover in CBA/Ca, CBA/N and CBA/N-bcl-2 transgenic mice: xid-mediated failure among pre B cells is unaltered by bcl-2 overexpression.

The CBA/N strain carries xid, a murine btk missense mutation that reduces peripheral B cell numbers. Using in vivo BrdU labeling and cytofluorimetry, we have compared the magnitude, production rates, and turnover rates of each B lineage subset in the marrow and periphery of CBA/Ca and CBA/N mice. Our results show the pro-B compartment is largely unaffected by xid. In contrast, the pre-B cell pool is markedly reduced, reflecting a diminished production rate and unaltered turnover time. Despite diminished pre-B cell formation, the size of the immature B cell pool is relatively normal in CBA/N mice, due to increased proportional survival of pre-B cells. In addition, we have assessed the marrow and peripheral B cell subsets of CBA/N mice transgenic for bcl-2. These results indicate that while the bcl-2 transgene promotes lengthened survival in most B cell subsets, the pro/pre-B cell losses mediated by xid are not abrogated by bcl-2 overexpression. Taken together, these findings suggest that the initial [not readable: see text] from the pro- to pre-B cell pools, and that anomalies in subsequent compartments likely reflects the action of homeostatic mechanisms compensating for compromised pre-B cell production.

Agammaglobulinaemia Tyrosine Kinase↗
PubMed2000

The frequency and proliferative potential of megakaryocytic colony-forming cells (Meg-CFC) in cord blood, cytokine-mobilized peripheral blood and bone marrow, and their correlation with total CFC numbers: implications for the quantitation of Meg-CFC to predict platelet engraftment following cord blood transplantation.

CFC numbers have shown to correlate with success of engraftment and speed of neutrophil recovery following cord blood (CB) transplantation. To investigate whether the number of Meg-CFC in a CB stem cell preparation might correlate with time to platelet engraftment, we evaluated the frequency of Meg-CFC among all CFC types in 134 CB, 21 adult bone marrow (BM) and 52 cytokine-mobilized peripheral blood (PB) stem cell preparations. The correlation of Meg-CFC with the total number of CFC and mixed cell-CFC was also assessed. The frequency of Meg-CFC was highest in CB and correlated significantly with total CFC numbers (mean 20.8%, correlation coefficient (r) 0.84, P = 0.0001) compared with Meg-CFC from mobilized PB (mean 13.1%, r = 0.29, P = 0.07) and BM (mean 4%, r = 0. 39, P = 0.13). In addition, mixed-cell CFC numbers in CB were highly correlated with the total number of Meg-CFC (r = 0.7, P = 0.0001). No such correlations were found with mobilized PB or BM. We conclude that, based on the high degree of correlation between Meg-CFC and non-Meg-CFC numbers in CB, no additional information concerning time to platelet engraftment would be gained by routinely performing Meg-CFC assays in addition to non-Meg-CFC assays. The fact that CB Meg-CFC and mixed-cell CFC are strongly correlated suggests that CB Meg-CFC are more primitive than their counterparts in BM and PB and may reflect the number of stem cells in CB. Bone Marrow Transplantation (2000).

Adult↗
PubMed1989

Mutual interaction of vasoconstriction and endothelial damage in stenotic arteries.

Coronary artery vasomotion may be important in the pathogenesis of angina pectoris. Numerous experimental studies demonstrated accentuated arterial vasomotion in endothelium-damaged vessels. We examined interactions of stenosis, arterial vasoconstriction, and endothelium denudation in a stenosed artery preparation in vitro. Canine carotid arteries and porcine coronary arteries were perfused with a physiological salt solution under constant pressure and a fixed distal resistance. Pressures at the proximal and distal ends of the artery, as well as the flow, were continuously recorded. Hemodynamic responses to serotonin, norepinephrine, and angiotensin II were separately studied. In intact arteries without stenosis, the agonists produced a 30-40% reduction in lumen diameter without altering flow or distal pressure. After a luminal stenosis was created, vasoconstriction produced by the agonists decreased flow and increased the pressure gradient across the stenosis. Flow decreased to (or near) zero, indicating occlusion at the stenotic site. After endothelial loss, this effect was amplified, demonstrating occlusion of the artery and suppression of the flow at significantly (P less than 0.05) lower concentrations of agonist (0.1-0.3) compared with endothelial intact arteries. These studies illustrate 1) the necessity for the presence of stenosis in large arteries for vasoconstriction to impair flow and 2) the protecting effect of intact endothelium in blunting the effects of arterial vasoconstriction in stenosed vessels. Through the reciprocal interaction of arterial stenosis, vasoconstriction, and endothelial damage, ischemic events associated with certain types of vasomotion can be explained.

Angiotensin II↗
PubMed1975

Serotonin through pregnancy. Comparative researches in different species and in mankind.

By spectrofluorimetric method there was followed the blood and cerebral serotonin content in different species of mammalians: in 28 women, from the venous whole blood collected by cubital puncture, and in 20 cows, from the jugular whole blood. In 90 female rats the serotonin content from hypothalamus, rhinencephalon, mesencephalon, and sensorimotor cortex was determined. The obtained data show that in the course of labour in both species the blood serotonin concentration is decreased, returning to its initial values after delivery. The serotonin concentration in cows is 10--15 times higher than in women. As concerns the serotonin values in the cerebral nuclei through pregnancy, a progressive and significant increase of its content was noted in the hypothalamus, rhinencephalon, and mesencephalon, but not in the cerebral cortex. It reaches its maximum concentration at the end of pregnancy. It was concluded that during pregnancy a reduction of serotonin release processes is produced, which can signify a lower functional level of the serotoninergic structures implied in the regulation of the reproductive functions. The data are interpreted in the light of the particular endocrine state existing through pregnancy, attributing to serotonin a role in the functioning of PIF-prolactin system.

Animals↗
PubMedDate not supplied

[Aortocoronary bypass].

Two cases are discussed, of severe myocardial ischaemia determined by coronary obstruction. The cases were solved by surgical treatment that consisted in direct myocardial revascularization with the aid of aorto-coronary by-pass with a fragment of autologous saphene vein.

Adult↗
PubMedDate not supplied

[Surgical treatment of interatrial septal defect].

On the basis of the authors' experience acquired between 1956 and 1973 (a total of 401 cases with inter-atrial communications and 234 cases of ostium secundum that have been operated by them), data are presented concerning the diagnostic means, the indications and the contra-indications of the surgical treatment, as well as the attitude to be adopted towards the associated lesions.

Adolescent↗
PubMedDate not supplied

[Personal experience with 2,500 closed heart mitral commissurotomies].

Between 1953 and 1976 a total of 2527 mitral commissurotomies have been performed in the Clinic for Cardio-Vascular Surgery of the "Fundeni" Hospital. This group included cases with pure mitral stenosis (predominantly following rheumatic disease), but also cases of mitral stenosis associated with other cardiac lesions in which the major hemodynamic element was the mitral obstruction. Criteria are discussed for surgery, the preoperative preparation of the patient, incidents, accidents and complications, as well as technical difficulties of the digital and/or instrumental mitral commissurotomies on closed heart, either carried out for the first time in the respective patient, or as iterative intervention. Comparing the results in relation with the functional stage of the disease (62.5% of the patients were classified in the III-IV evolutive degree, according to the NIHA classification), pulmonary hypertension (61.6% of the patients had medium or severe pulmonary hypertension), associated lesions (present in 17% of the cases--mitral failure predominated, together with tricuspid or aortic failures), it is appreciated that the technique of mitral commissurotomy on closed heart is an useful therapeutic method (88.6% very good and good results, a global death rate of 3.9%) that can be applied in a large category of patients, although there is a trend toward open-heart surgery, with all medico-economical major implications.

Humans↗
PubMedDate not supplied

[Frequency of tooth loss in children and young subjects].

The frequency of edentation was evaluated in groups of children and young subjects aged between 7 and 18 years. The values obtained for this indicator have focused the attention on the type of organization and the quality of the curative assistance. Models for the processing of clinical data, as well as a comparison of the existing situation in the growth period with that of the adults has led to the establishment of conclusions concerning practical measures for the organization of the specialized assistance to children and young subjects.

Adolescent↗