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Biomedical subjects

L Alvarez

Publications and source records attributed to L Alvarez.

At least 235 records · Page 13Linked to original sources
PubMed1990

Malignant melanoma with pseudocarcinomatous hyperplasia--an entity that can simulate squamous cell carcinoma. A light-microscopic and immunohistochemical study of four cases.

We report four unusual cases of malignant melanoma in which squamous cell carcinoma was strongly considered in the differential diagnosis on routine hematoxylin and eosin-stained sections due to the near absence of melanin and the presence of pseudocarcinomatous hyperplasia. Ultimately, immunohistochemical staining for S-100 protein and keratin established the correct diagnosis of malignant melanoma in all cases.

Aged↗
PubMed1990

Coexpression of intermediate filament proteins in the chick embryo heart.

We studied the distribution of intermediate filament proteins during several stages of chick embryo heart development by indirect immunofluorescence and fluorescence-activated cell surface analysis. Vimentin is the predominant intermediate filament during the early stages of cardiac genesis, while desmin appears essentially with maturation. Desmin is the main subunit protein of intermediate filaments in the mature myocyte.

Animals↗
PubMed1990

[Modulation of cardiac contractility in myogenesis using antidesmin monoclonal antibody].

The cytoskeleton of the myocardiocyte is a complex network of protein filaments. The intermediate filaments, consisting fundamentally of desmin, are considered markers of cellular differentiation. We used indirect immunofluorescence with specific monoclonal antibody to characterize the expression of desmin during the different phases of heart maturation, and demonstrated a direct relationship between the expression of this protein and myocardiocyte development. Our results show that in auricular myocardiocytes, desmin is present in early stages of development, whereas in ventricular myocardiocytes, this protein, which is intimately involved in contractile function, first appears in HH stage 25.

Animals↗
PubMed1989

Prevention of the formation of arterial thrombi using different antiplatelet drugs: experimental study in dogs.

We have induced the formation of arterial thrombosis in dogs by means of an intima lesion produced by continuous current. The platelets were labeled with 111-In-oxine. Groups of 7 mongrel dogs received treatment for 7 days prior to the trial: Group I, control; Group II, 5 mg/kg body weight/day acetylsalicylic acid; Group III, 20 mg/kg body wt/day acetylsalicylic acid; Group IV, 15 mg/kg body wt/day triflusal + 5 mg/kg body wt/day dipyridamole; Group V, 15 mg/kg body wt/day triflusal; and Group VI, 5 mg/kg body wt/day acetylsalicylic acid + 5 mg/kg body wt/day dipyridamole. The only effective treatment for arterial thrombosis prevention was that employed in Group II (p less than 0.05).

Animals↗
PubMed1989

Sinus node function and protamine sulfate.

This report analyzes the effects of protamine sulfate (PS) on the heart rate and sinoatrial node function in dogs anesthetized with diazepam, fentanyl, and pancuronium bromide, and subjected to different modalities of extracorporeal circulation (ECC). All groups were given 3 mg/kg of heparin sodium and 5 mg/kg of PS. The sinus node function was evaluated by means of sinoatrial conduction time (SACT), absolute sinus node recovery time (SNRTa), and corrected sinus node recovery time (SNRTc). The spontaneous heart rate (HR) of the animals was also analyzed. Under the experimental conditions established in this study, the intravenous administration of a bolus of PS produced a decrease in the HR in all the groups, regardless of the type of ECC used. The modifications in the conduction and recovery times of the sinus node by PS did not correlate with those of the heart rate; the sinoatrial conduction time increased in groups subjected to ECC, while the absolute and corrected recovery times of the sinus node were prolonged only in the group that underwent rapid rewarming.

Animals↗
PubMed1989

Benzodiazepine use and abuse by patients at outpatient clinics.

The charts of 2,719 patients from several outpatient clinics were reviewed for evidence of use and abuse of benzodiazepines. According to the chart data and interviews with physicians, no patient met the criteria for benzodiazepine abuse or dependence.

Aged↗
PubMed1989

Dysplastic gangliocytoma and intractable partial seizures in childhood.

We describe the clinical, radiologic, and EEG features of 3 children who had dysplastic gangliocytomas of the cerebral hemispheres and drug resistant partial seizures that began in infancy. Following cortical resection, 2 are seizure-free and the third almost seizure-free. The dysplastic gangliocytoma may be an important and surgically remediable cause of very early malignant partial seizures.

Adolescent↗
PubMed1989

[Use of aspirin in the primary prevention of vascular thrombi. A comparative study with other anti-aggregant drugs].

We have induced the formation of arterial (carotid) and venous (femoral) thrombi in dogs by means of an intima lesion produced by continuous current. The platelets were labeled with 111In oxine. Groups of 7 mongrel dogs received treatment for 7 days prior to the trial: group I, control; group II, 5 mg/kg body weight/day acetylsalicylic acid; group III, 20 mg/kg body weight/day acetylsalicylic acid; group IV, 15 mg/kg body weight/day triflusal + 5 mg/kg body weight/day dipyridamole; group V, 15 mg/kg body weight/day triflusal; and group VI, 5 mg/kg body weight/day acetylsalicylic acid + 5 mg/kg body weight/day dipyridamole. The only effective treatment for arterial thrombosis prevention was that employed in group II (p less than 0.05). Venous thrombosis was prevented in groups II (p less than 0.01), III (p less than 0.01) and VI (p less than 0.01).

Animals↗
PubMed1989

Prostaglandins and transepithelial ionic transport.

Given the complexity of the preparation and the fact that the measured potential difference and SCC result from the algebraic contribution of several apparent ionic components (as well as unidentified ones) in the various cell membranes of the preparation, the effect of PGF2 alpha on the SCC requires further elucidation, for example, by determination of the effects of this PG on H14CO3- fluxes. However, experiments already completed suggest that PGF2 alpha can effectively stimulate the SCC of the ciliary epithelium. Since stimulation of the SCC can be expected to reflect enhanced fluid secretion, the effect of PGF2 alpha on the ciliary epithelium, at least in rabbits, can be regarded as a potentially beneficial one, providing increased production of aqueous humor. It remains to be seen whether PGF2 alpha has a similar stimulatory effect on ciliary epithelium transport function in primates whose aqueous humor, in contrast to rabbits, is deficient in HCO3- as compared to blood plasma. The possibility that PGF2 alpha does stimulate aqueous humor secretion in the human eye is suggested by the fact that PGF2 alpha-1-isopropylester applied topically to the human eye in doses greater than the minimal dose required to cause ocular hypotension yields an initial increase in intraocular pressure (see Alm and Villumsen, 1989) and a small increase in rate of aqueous production was detected in the PGF2 alpha treated eyes of cynomolgus monkeys (Nilsson et al., 1989). These considerations suggest that the effects of PGs on the transport function of the mammalian ciliary epithelium deserves further attention.

Animals↗
PubMed1988

Testosterone induces the expression of the uteroglobin gene in rabbit epididymis.

Uteroglobin was characterized in the rabbit epididymis by radioimmunoassay and electrophoretic determinations, as well as by analysis of its mRNA by means of 'Northern blot' and nuclease-S1 mapping. Treatment of sexually immature rabbits with testosterone during 5 days increased up to 8-fold the concentrations of both uteroglobin and its mRNA in the epididymis. The amounts of beta-tubulin mRNA, measured as reference, remained unchanged after the hormonal treatment. The synthesis of uteroglobin occurred mainly in the middle region of the epididymis, progressively decreasing toward the distal part of the organ. Uteroglobin was not detected in the testis by radioimmunoassay. The results are discussed in relation to a possible role of uteroglobin in the reproductive functions.

Animals↗
PubMed1988

Hemodynamic and morphologic alterations after experimental administration of protamine sulfate.

The hemodynamic, hematologic, and morphologic effects induced by protamine sulfate have been studied in 28 dogs divided into 6 groups. All of the groups were given heparin (3 mg/kg body weight) and Groups I, II, III, and IV were given protamine (5 mg/kg body weight). Group I (control group) was not subjected to extracorporeal circulation. The other groups had the following interventions: Group II, cardiopulmonary bypass without aortic clamp, hypothermia, or cardioplegia; Groups III and V, hypothermia of 25 degrees C, aortic clamping for 25 minutes, administration of cardioplegic solution, and slow rewarming; and Groups IV and VI, the same as Groups III and V, but with rapid rewarming. After injection of protamine sulfate, there was a decrease in mean arterial pressure due to peripheral vasodilation and an increase in the mean pulmonary pressure due to increased pulmonary vascular resistance; marked diminution of the number of circulating platelets aside from the extracorporeal circulation; a decrease in the contractility of both ventricles with augmented right ventricular work and decreased cardiac output; and right ventricular edema in Groups I, II, III, and IV. These alterations were most evident in Groups III and IV.

Animals↗
PubMed1988

Morphometric study of right ventricle in 32 cases of tetralogy of Fallot.

The right ventricle was the object of a morphometric study in a total of 32 human hearts with tetralogy of Fallot. Most subjects died in the perinatal period and weighed between 720 and 5,000 g. Nine internal parameters were measured in each right ventricle and substituted into the appropriate stereometric formula to yield volumes for each right ventricular chamber. The data obtained were compared to patterns of normality previously obtained by mathematical analysis. The results can be summarized as follows: 1. The right ventricular wall in the present series was thicker than normal, particularly near the tricuspid valve annulus. 2. Pulmonary valve and pulmonary infundibulum perimeter were below normal. 3. Tricuspid valve perimeter was above normal. 4. Above normal figures were obtained for length and volume of the right ventricular inflow tract. 5. Increased outflow tract length contrasted with below normal figures for outflow tract volume. 6. In a large number of cases (95%) the distance between the crista supraventricularis and the pulmonary sigmoid leaflets was reduced. Characterization of these changes may help to elucidate the embryological origin of tetralogy of Fallot.

Cardiac Volume↗
PubMed1987

A new family affected by the syndrome of hyperornithinaemia, hyperammonaemia and homocitrullinuria.

We have reported three cases of hyperornithinaemia associated with hyperammonaemia and homocitrullinuria (HHH). They deal with two brothers and a sister from a family where the parents and four other children are healthy on clinical and biochemical examination. The biochemical findings in our patients indicate the existence of a defect in the transport of ornithine into the mitochondria. Cultured skin fibroblasts from two of these patients incorporated six times less [14C]ornithine into protein as compared to control cells. The most characteristic sign of the clinical picture is the progressive spastic paraparesis found in one of the cases. Ornithine supplementation and restricted protein intake may be useful in the treatment of this syndrome since after three years of treatment the clinical response was favourable and the patients showed no adverse clinical effects.

Adolescent↗
PubMed1987

The quantitative anatomy of the normal human heart in fetal and perinatal life.

A total of 367 human fetuses and newborn subjects weighing from 60 to 5000 g provided the material for a morphometric study of the heart. A total of 17 interventricular parameters were measured in each specimen, one of the parameters representing an innovation with regard to the classically used set of measurements. A new anatomo-geometric configuration is described for each ventricle along with a new component for the left ventricular outflow tract, designated as the aortic outflow tract. The appropriate stereometric formulas were used to calculate real ventricular volumes rather than the previously studied volumetric indices. Additionally, correlation indices were calculated for ventricular wall thickness as well as the circumferences and diameters of the atrioventricular and arterial valves. The results show that, in fetuses of up to 2700 g in body weight, ventricular wall thickness is greater in the right than in the left ventricle, although the opposite is true in fetuses weighing above 2700 g. Throughout the range of weights studied, ventricular volume was greater in the left than in the right chamber. Tricuspid and pulmonary valve circumference and diameter were consistently greater than in the mitral and aortic valves, respectively. We believe the new morphometric data and their innovative interpretation to have immediate applications in both the morphological and functional areas of cardiology.

Aortic Valve↗
PubMed1987

Mucinous cystadenocarcinoma of the pancreas. Morphologic and immunocytochemical observations.

Twenty mucinous cystadenocarcinomas of the pancreas, most of which occurred in the tail of the pancreas in middle-aged women, were examined histologically and by immunohistochemical stains. Thirteen tumors displayed a marked histological heterogeneity and expressed intestinal differentiation as shown by the colonic appearance of the glands both at the light- and electron-microscopic levels. Other intestinal features included varying numbers of goblet cells, argyrophil and argentaffin cells, and even Paneth cells. By immunohistochemistry, endocrine cells were present in 13 of the 20 tumors (65%) and were more numerous in the poorly differentiated than in the well-differentiated epithelial component of the tumors. Serotonin-containing cells were the most common endocrine cells, followed by somatostatin-containing cells and cells that showed immunoreactivity for pancreatic polypeptide and gastrin. However, none of the patients had clinical manifestations of carcinoid, somatostatinoma, or the Zollinger-Ellison syndrome. The findings support the hypothesis that mucinous cystadenocarcinomas of the pancreas arise from an "endodermal stem cell" that differentiates into cells with intestinal phenotypes.

Adult↗
PubMed1987

Coagulation defects during extracorporeal circulation in the dog.

This study was undertaken in an attempt to diminish the frequency and severity of postextracorporeal circulation hemorrhage in dogs. Its purpose is to ascertain the amount of 99mTc-labeled autologous fibrinogen deposited in the oxygenator, as well as the coagulation defect originated during the surgical procedure when heparin is not administered (group I) and when it is at doses of 1 mg/kg body weight (group II) and 3 mg/kg body weight (group III). The result demonstrate that the fibrinogen deposition in the oxygenator decreased as the dose of heparin administered was augmented. The coagulation disorders were produced by factor consumption, affecting all dogs in group I. The same type of alteration was produced with the use of heparin, but in some the platelet count, fibrinogen and fibrinogen degradation products and the prothrombin and thrombin times were maintained within normality or were only slightly altered. Significant differences were not detected between groups II and III. For this reason, we recommend the utilization of heparin in experimental extracorporeal circulation in a single dose of 1 mg/kg body weight, administered at the initiation of bypass, which provides a sufficient level of anticoagulation for at least 60 min and makes its neutralization with protamine unnecessary, the effects of which are especially adverse in the dog.

Animals↗