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Biomedical subjects

M Presta

Publications and source records attributed to M Presta.

143 records · Page 8Linked to original sources
PubMed1982

Liver tumors induced by a new beta-adrenoreceptor blocking agent in female rats.

A newly synthesized beta-adrenoreceptor blocking agent, DL-1-(2-nitro-3-methyl-phenoxy)-3-tert-butylamino-propan-2-ol (ZAMI 1305), administered intragastrically for 6 months induced hepatocellular carcinomas in female outbred Wistar rats in a dose-dependent fashion but was harmless to the livers of male outbred Wistar rats. Experiments with castrated animals confirmed the dependence of the carcinogenic effect of ZAMI 1305 on the hormonal status of the rat. When an isomer of ZAMI 1305, DL-1-(2-nitro-5-methyl-phenoxy)-3-tert-butylamino-propan-2-ol (ZAMI 1327), and DL-practolol, which have pharmacologic activities similar to those of ZAMI 1305, were administered by the same experimental technique as used for ZAMI 1305, no liver tumors appeared either in male or female rats.

Adrenergic beta-Antagonists↗
PubMed1981

Quantification of damage to striated muscle after normothermic or hypothermic ischemia.

Muscular ischemia of different duration was induced by use of a tourniquet applied to the rear left leg of rabbits under normothermic or hypothermic conditions, and variations in serum creatine kinase, lactate dehydrogenase, K+, Ca2+, and lactate were determined at various intervals after blood flow was restored. A monocompartmental model analysis applied to the activities of the two enzymes in the serum demonstrated that: (a) the total enzyme activity leaked into the blood is proportional to the duration of normothermic but not of hypothermic ischemia; (b) this enzyme leakage persists until at least the third day after blood flow is restored; (c) a substantial part of the ischemic damage seems to occur as a consequence of re-perfusion, not of the ischemia itself; and (d) hypothermia greatly minimizes the ischemic damage. The data we obtained for K+ and for lactate confirm the protective effect of hypothermia.

Animals↗
PubMed1979

Inhibition of protein synthesis in ischaemic liver from phenobarbitone-treated rat.

Both ribosomal factors and cytosolic inhibitors are involved in the reduction of the rate of protein synthesis which occurs in the ischaemic hepatocyte from control and phenobarbitone-treated livers. Of these 2 factors it is the latter which seems to play a major role in determining the irreversible impairment of protein synthesis. Phenobarbitone administration has no effect on the rate of protein synthesis of ischaemic and post-ischaemic hepatocyte.

Animals↗
PubMed1979

PRediction of infarct size by enzymatic techniques: modification of a method and clinical application.

In an attempt to develop improved methods of prediction of infarct size by enzymatic methods, Shell's original algorithm has been critically evaluated in an unselected series of patients. Poor performance of the model is partly the result of a systematic source of error associated with its mathematical formulation. A new model devoid of such limitations has therefore been developed. Residual deviations between predicted and observed CK release seem to be related to frequent and unpredictable extensions of infarction which could be verified by independent clinical, electrocardiographic, and enzymatic criteria. The modified model may possibly be applied to the evaluation of agents aimed at limiting the spread of irreversible injury.

Clinical Enzyme Tests↗
PubMedDate not supplied

Role of fibroblast growth factor-2 in human brain: a focus on development.

Trophic factors have gained a great degree of attention as regulators of neural cells proliferation and differentiation as well as of brain maturation. Very little is known, however, about their effects on human immature nervous system. In this paper, data on expression of fibroblast-growth factor-2 and its receptors are reviewed and discussed in the light of its possible role in human brain development.

Brain↗
PubMedDate not supplied

The role of fibroblast growth factor-2 in the vascularization of the chick embryo chorioallantoic membrane.

The CAM is an extraembryonic membrane which serves as a gas exchange surface and its respiratory function is provided by an extensive capillary network. The development of the vascular system of the CAM is a complex, highly regulated process that depends on genetic and epigenetic factors expressed by endothelial and non-endothelial cells. In spite of the evidence that several growth factors are angiogenic in the CAM assay, poorly investigated is their role in the development of the CAM's vascular system. This article reviews our studies concerning the role of exogenous and endogenous fibroblast growth factor-2 (FGF-2) in the CAM vascularization. The findings in all these studies support the importance of FGF-2 as an autocrine paracrine stimulator of angiogenesis and its key role in the development of the vascular system in the avian embryo.

Allantois↗
PubMedDate not supplied

Cell-mediated delivery of fibroblast growth factor-2 and vascular endothelial growth factor onto the chick chorioallantoic membrane: endothelial fenestration and angiogenesis.

Fibroblast growth factor-2 (FGF2) and vascular endothelial growth factor (VEGF) exert their angiogenic activity by interacting with endothelial cells in a distinct manner. In this study, we investigated the morphological features of endothelial cells of the chick embryo chorioallantoic membrane (CAM) microvasculature after stimulation with FGF2 or VEGF. In order to provide a continuous delivery of the growth factor, we utilized a recently developed gelatin sponge/CAM assay in which a limited number of FGF2- or VEGF-transfected cells were adsorbed onto gelatin sponges and applied on the top of the CAM on day 8 of development. Their angiogenic activity was compared to that exerted by a single bolus of the corresponding growth factor. All the angiogenic stimuli induced a comparable vasoproliferative response, as demonstrated by the appearance of similar numbers of immature blood vessels within the sponge on day 12. No angiogenic response was observed in CAMs implanted with the corresponding parental cell lines or vehicle. Electron microscopy demonstrated that VEGF-overexpressing cells modified the phenotype of the endothelium of the blood vessels at the boundary between the implant and the surrounding CAM mesenchyme. The endothelial lining of 30% of these vessels showed segmental attenuations, was frequently interrupted and became fenestrated, mimicking what is observed in tumor vasculature. In contrast, the vessels consisted of continuous endothelium sealed by tight junctions in all the other experimental conditions. These results indicate that FGF2 and VEGF interact with endothelial cells of the CAM in a distinct manner. Both growth factors induce a potent angiogenic response, but only VEGF delivered in a continuous manner by its transfectants can modify the phenotype of the otherwise quiescent endothelium of CAM blood microvessels. The gelatin sponge/CAM assay may constitute a new model to study the mechanisms leading to endothelial fenestration in tumor growth.

Adsorption↗
PubMedDate not supplied

New model for the study of angiogenesis and antiangiogenesis in the chick embryo chorioallantoic membrane: the gelatin sponge/chorioallantoic membrane assay.

Several methods for the in vivo study of angiogenesis are available, and each angiogenic assay presents distinct advantages and disadvantages. In this study, we present a new method for the quantitation of angiogenesis and antiangiogenesis in the chick embryo chorioallantoic membrane (CAM), based on the implantation of gelatin sponges on the top of growing CAM, on day 8 of incubation. After implantation, the sponges were treated with a stimulator (recombinant human basic fibroblast growth factor, FGF2) or an inhibitor (a rabbit polyclonal anti-FGF2 antibody) of blood vessel formation. Blood vessels growing vertically into the sponge and at the boundary between sponge and surrounding CAM mesenchyme were counted by a morphometric method on day 12. In addition, to assess whether the gelatin sponge is an appropriate vehicle to deliver cultured cells and evaluate their angiogenic potential, mouse aortic endothelial cells were cotransfected with human FGF2 and the Escherichia coli beta-galactosidase (beta-GAL) reporter gene. Stable transfectants were absorbed by the sponge, and evaluation of the angiogenic response was paralleled by beta-GAL staining to visualize implanted cells. This technique may facilitate the discovery and development of agonists or antagonists of angiogenesis.

Allantois↗
PubMedDate not supplied

Purification and biological activities of an angiogenesis factor from human placenta.

Several crude angiogenesis preparations, as well as a purified angiogenesis factor from human placenta, were tested for their ability to stimulate the production of plasminogen activator (PA) and collagenase activities, motility, chemotaxis, DNA synthesis and clonal growth in cultured endothelial cells. Treatment of capillary endothelial cells resulted in a stimulation of all the above activities, whereas endothelial cells derived from large vessels did not respond. These cellular activities are postulated to be responsible for capillary growth in vivo.

Angiogenesis Inducing Agents↗