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Biomedical subjects

R Carmona

Publications and source records attributed to R Carmona.

At least 37 records · Page 2Linked to original sources
PubMed1997

Suppression of angiotensin-converting enzyme expression and activity by shear stress.

Shear stress caused by the frictional forces of a fluid moving over a cell monolayer is an important regulator of gene expression. In this study, we investigated the effect of shear stress on angiotensin-converting enzyme (ACE) expression and promoter activity in vitro and on local vascular ACE activity in vivo. ACE activity measured in bovine pulmonary artery endothelial (BPAE) cells was reduced by 49.5% after exposure to a shear stress of 20 dyne/cm2 for 18 hours. Short-term shearing (2 hours) elevated ACE activity in BPAE cells, whereas long-term shearing produced a time-dependent reduction in ACE activity by 23.3%, 33.5%, and 48.9% at 8, 12, and 18 hours, respectively. Northern blot analysis revealed that shear stress (20 dyne/cm2 for 18 hours) significantly reduced ACE mRNA expression by 82%. To determine the mechanism of ACE activity and message reduction, the effect of shear on transcriptionally related events was determined in a rabbit aortic endothelial cell line (W3LUC) stably transfected with 1.3 kb of a rat ACE promoter/luciferase construct. Different shear stress magnitudes (5 to 20 dyne/cm2) caused suppression of luciferase activity by an average of 40.7%. ACE promoter activity was suppressed by 2 hours of shear stress (24.7%) and was further inhibited at time periods > 8 hours. In vivo elevations in shear stress were created by placing a stainless steel clip over a 12-mm region of the rat abdominal aorta. Restriction of vessel diameter increased blood flow velocity and caused reduction in vascular ACE activity by 40%. These studies suggest that elevations in the level of shear stress alter endothelial cell function by suppressing ACE gene and protein expression in vitro and in vivo.

Acetylcholine↗
PubMed1994

Effect of dietary nucleotides on small intestinal repair after diarrhoea. Histological and ultrastructural changes.

The effects of specific nutrients on intestinal maturation and repair after injury are practically unknown. The purpose of this work was to study the effects of dietary nucleotides on the repair of the intestinal mucosa after chronic diarrhoea induced by a lactose enriched diet in the weanling rat. One group of weanling rats was fed with a standard semipurified diet (control group), and another group was fed with the same diet containing lactose as the only soluble carbohydrate (lactose group). After 14 days the lactose group was allowed to recover for four weeks with the control diet (lactose-control group) or with the control diet supplemented with AMP, GMP, IMP, CMP, and UMP 50 mg/100 g each (lactose-nucleotide group). The control group was divided into two subgroups, which were fed with the control diet and the nucleotide supplemented diet for the same period (control-control group and control-nucleotide group). The lactose diet induced diarrhoea after 24 hours of feeding. Two weeks later there were changes in intestinal structure with loss of enterocyte microvillar surface, significant lymphocyte infiltration, supranuclear cytoplasmic vesiculation, decreased number of goblet cells, and enlarged mitochondria with low density and few cristae. After recovery from diarrhoea, animals fed the nucleotide enriched diet showed an intestinal histology and ultrastructure closer to that of the normal control group. Mitochondrial ultrastructure was closer to normal in comparison with the lactose-control diet group. In this second group the number of goblet cells as well as the villous height/crypt depth ratio was reduced and the number of intraepithelial lymphocytes increased compared with the nucleotide supplemented group. These results suggest that dietary nucleotides may be important nutrients for intestinal repair.

Animals↗
PubMed1994

Quantitative alterations after long-term alcohol administration in the dorsal lateral geniculate nucleus (dLGN) in the rabbit (Oryctolagus cuniculus).

The effects of chronic excessive alcohol ingestion on the central nervous system were studied in neurons of the dorsal lateral geniculate nucleus (dLGN) in the rabbit (Oryctolagus cuniculus). In this nucleus, neuron density and other morphometric parameters such as the somatic volume of the cells have been investigated both under normal conditions and under alcohol intoxication. Special attention was given to the possibility that positive somatic heteropycnosis may be a sign of imminent cell death. In addition, the percentage volumes occupied by normal neuronal soma and by affected cells were determined. Continuous alcohol treatment for 6 months reduced the size of certain types of neurons, the alteration being specially intense in areas with an abundance of larger neurons. In these areas more intense signs of somatic heteropycnosis also appeared. We discuss the relationship between the condition of the inhibitory neurons (GABAergic interneurons), the distribution of these in the lower zone of the nucleus, and their greater resistance to the influence of alcohol. This type of stereological analysis is intended to provide a better interpretation of the different degrees of the effects of alcohol, and to give more detailed information about changes at cellular level, both for comparative purposes with other situations and to shed light on the alterations caused by alcoholism.

Alcoholism↗
PubMed1993

Morphological changes induced by colchicine in the chick optic cup in early stages of development. A stereological study.

In this study chick embryo optic cups at HH stage 13 of development were analyzed under normal conditions and after inoculation with colchicine for 1, 2, 4, and 8 h. Several changes were seen after these periods of treatment: 1) modifications of the structure, with thicker regions in the cup and a general decrease in the total volume according to the duration of exposure to the drug (about 4 times less than normal, 5,035 x 10(3) microns 3 vs 1,334 x 10(3) microns 3 after 8 h of treatment); 2) enlargement of the ventricular cavity and its closure, due to failure of approximation of retinal and pigmentary layers; 3) failure of lens development, with delay and impairment of pit formation and deformation of all structures; lens volume was less than normal (about 4 times less, 2,148 x 10(3) microns 3 vs 658 x 10(3) microns 3 after 8 h of treatment); 4) a general segregation of the cells making up the structure, principally in the more active proliferating zones. The local alterations found are described.

Animals↗
PubMed1990

Morphometry and frequency of afferent synaptic terminals in the rabbit dorsal-lateral geniculate nucleus.

Morphological and morphometric features of the retinal synaptic terminals (RLP) and cortical synaptic terminals (RSD) were analyzed in the alpha E sector of the rabbit dorsal-lateral geniculate nucleus (dLGN). A methodological approach was selected which allowed us to determine volume of the neuropil and elsewhere record variations in the size and distribution of the two types of terminals found in the three zones (superior, middle, and inferior) from up to down into which the alpha E sector of the dLGN was divided. After obtaining an isotropic, uniform, and pseudorandom (IUR) sample, the terminals were examined on the basis of a set of morphometric parameters. An analysis of these data showed the retinal terminals (RLP) to be more numerous and to occupy a greater total area of the neuropil in the dorsal (superior) zone of the nucleus, whereas the number and total area occupied by cortical terminals (RSD) did not vary in the superior, middle, and inferior zones. Upon comparing the two types of terminals, the RLP were larger and more widely distributed, the greatest differences between the two appearing in the dorsal (superior) zone of the dLGN.

Animals↗
PubMed1990

The effect of alcohol in isolated blunt splenic trauma.

The effect of alcohol on trauma patients is controversial, with numerous authors citing no difference in mortality in acutely intoxicated patients. The purpose of our study was to retrospectively investigate the effect of alcohol in adult patients with isolated blunt splenic injury. From 1980 through 1989, 47 adult patients with splenic trauma as the only major injury were admitted to the Trauma Service. There were 37 males and ten females with a mean age of 29 years (range, 15 to 61). Motor vehicle accidents were responsible for 44 (94%) of the injuries. Group 1 consisted of 24 patients with a mean blood alcohol level of 185 mg/dl (range, 15 to 380). In Group 2 there were 23 patients without detectable blood alcohol. There were no statistically significant differences between the two groups in age, Abbreviated Injury Severity Score, initial hematocrit, and grade of splenic injury. Hypotension was present in 13 patients (55%) in Group 1 versus six patients (26%) in Group 2 (p less than 0.05). Significant abnormalities in clotting studies were present on admission in six patients (25%) in the alcohol-detected group versus one in the other group (p less than 0.05). Blood transfusion requirements in the first 24 hours were significantly greater in Group 1 (mean, 3.9 units) versus Group 2 (mean, 0.5 units) (p less than 0.001). If alcohol was present, there was much less chance for splenic conservation, as 18 patients (75%) underwent splenectomy versus seven patients (30%) in the nonalcohol group (p less than 0.05). There was one death and this occurred in a patient acutely intoxicated who suffered a cerebral infarct.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗
PubMed1990

The management of splenic trauma in the adult patient with blunt multiple injuries.

An analysis of 106 adult patients with blunt multiple organ injury and splenic trauma was carried out during an eight year period. Three groups were studied--group 1, splenectomy; group 2, splenorrhaphy, and group 3, observation. There was no statistically significant difference in initial blood pressure, pulse or hematocrit among the three groups. The mean injury severity score (ISS) was higher for those in groups 1 and 2 (26.8 and 25.6, respectively) versus patients in group 3 (17.9) (p). There were a total of 38 intra-abdominal injuries in 34 patients of which 21 required surgical repair. No patient in the nonoperative group required laparotomy for a missed associated intra-abdominal injury. There were a total of 15 intra-abdominal complications related to splenic management. In the observation group, seven patients ultimately required laparotomy for continued splenic bleeding. In the splenorrhaphy group, the complication rate was significantly lower versus the other two groups (p). We concluded that, if technically feasible, splenorrhaphy is a safe procedure in the multiply injured patient in the absence of hypotension and coagulopathy. Nonoperative management of blunt splenic trauma should be viewed with caution because of the high failure rate in the multiply injured patient.

Adult↗
PubMed1989

Trauma and forensic medicine.

Trauma physicians are frequently involved in the evaluation and treatment of patients who are victims of crimes or themselves criminals. These physicians usually have little or no training in the forensic aspects of emergency medical care and therefore necessary evidence may often be overlooked, lost, inadvertently discarded, or its admissibility denied because of improper handling or documentation. Criteria were developed to evaluate the forensic medical aspects of such trauma cases and to discern the magnitude of the problem. The majority of the cases reviewed demonstrated significant forensic medical deficiencies primarily in the areas of documentation and/or handling or securing of evidence. Trauma physicians have the responsibility and potential liability to insure that necessary evidence is properly secured and preserved while caring for their patients. Educational programs should be developed for this purpose.

Accidents↗
PubMed1988

Stereological study on the mode of optic cup expansion and the accumulation of mitoses in the early stages of chick embryo development.

The present study was designed to contribute to our understanding of the factors that take part in the developmental transformation of the optic vesicle into the optic cup. The expansion and formation of this structure are dependent upon factors such as cellular proliferation, the space or zone occupied by the growing optic cup, and environmental influences. Our investigation in the chick embryo analyzes the relationship between retinal thickness and ventricular mitotic density. This relationship is shown in the study as PEI (proliferation-expansion index). That index varies in the superior, medial and inferior regions of the retina when the zones of the same stage are compared, as well as in the comparisons of values between the 13-14 stage and the 17-18 stage. These differences indicate a different behavior of the cells constituting the retinal regions. Also discussed is the influence of the retinal fissure on the morphological changes observed during optic cup development.

Animals↗
PubMed1987

Acute cholecystitis in pregnancy.

Thirty cases of acute cholecystitis in pregnancy were identified during a 12-year period. Twenty-one patients were successfully managed with medical therapy alone. Nine underwent surgical intervention, four after failing medical therapy and five as the initial approach to therapy. Surgical therapy was complicated by preterm labor and delivery in two patients undergoing surgery during the early third trimester. One patient underwent cholecystectomy during the first trimester and subsequently aborted. There were no serious complications in patients undergoing surgery during the second trimester. These data suggest that conservative medical management can be successfully used in most patients with acute cholecystitis in pregnancy.

Abortion, Spontaneous↗
PubMed1983

Pigments with antibiotic activity from Myxococcus coralloides.

A strain of Myxococcus coralloides produces pigments with antibiotic activity. The pigments are non-diffusible and become detectable at the beginning of the autolytic phase. Red pigments produced by vegetatively growing cells were extracted by acetone treatment. The crude extract when chromatographed yielded several fractions, two of which were active against certain Gram-positive bacteria. Both fractions were partial purified in thin layer chromatography and can be differentiated according to colour, polarity and absorption spectrum. Production of active pigments is increased by nicotine and inhibited by diphenylamine. The pigments are also compared with the antibiotic produced by this bacterium.

Anti-Bacterial Agents↗
PubMedDate not supplied

The origin of the endothelial cells: an evo-devo approach for the invertebrate/vertebrate transition of the circulatory system.

Circulatory systems of vertebrate and invertebrate metazoans are very different. Large vessels of invertebrates are constituted of spaces and lacunae located between the basement membranes of endodermal and mesodermal epithelia, and they lack an endothelial lining. Myoepithelial differentation of the coelomic cells covering hemal spaces is a frequent event, and myoepithelial cells often form microvessels in some large invertebrates. There is no phylogenetic theory about the origin of the endothelial cells in vertebrates. We herein propose that endothelial cells originated from a type of specialized blood cells, called amoebocytes, that adhere to the vascular basement membrane. The transition between amoebocytes and endothelium involved the acquisition of an epithelial phenotype. We suggest that immunological cooperation was the earliest function of these protoendothelial cells. Furthermore, their ability to transiently recover the migratory, invasive phenotype of amoebocytes (i.e., the angiogenic phenotype) allowed for vascular growth from the original visceral areas to the well-developed somatic areas of vertebrates (especially the tail, head, and neural tube). We also hypothesize that pericytes and smooth muscle cells derived from myoepithelial cells detached from the coelomic lining. As the origin of blood cells in invertebrates is probably coelomic, our hypothesis relates the origin of all the elements of the circulatory system with the coelomic wall. We have collected from the literature a number of comparative and developmental data supporting our hypothesis, for example the localization of the vascular endothelial growth factor receptor-2 ortholog in hemocytes of Drosophila or the fact that circulating progenitors can differentiate into endothelial cells even in adult vertebrates.

Animals↗