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Biomedical subjects

F Alvarez

Publications and source records attributed to F Alvarez.

At least 289 records · Page 16Linked to original sources
PubMed1981

The Rose Bengal test in neonatal cholestasis: diagnostic and prognostic value.

131I Rose Bengal(131IRB) studies were performed in 73 infants with extrahepatic biliary atresia (EHBA) and in 37 with intrahepatic cholestasis of various origins. Fecal 131IRB excretion of less than 10% ("complete' cholestasis) was observed in EHBA but also in some patients with either paucity of intrahepatic bile ducts (syndromatic type) or with alpha-1-antitrypsin deficiency. Seventy one 131IRB tests were also performed 3 to 8 weeks postoperatively in children operated on for EHBA. Fecal 131IRB excretion more than 15% was present in 27 out of 34 cases who were later completely jaundice free and in only one out of 37 cases where no bile flow restoration occurred. These results indicate that complete cholestasis in infants can be observed in some types of intrahepatic cholestasis, as well as in EHBA, and show that a post-operative 131IRB test is a reliable means of predicting complete restoration of bile flow in EHBA.

Bile Ducts↗
PubMed1981

Lipoprotein patterns in women in Santo Domingo using a levonorgestrel/estradiol contraceptive ring.

Ten healthy, normally menstruating women attending a family planning clinic in Santo Domingo Participated in a study to determine the effects on plasma lipid levels of levonorgestrel and estradiol released from a contraceptive ring. A schedule of 21 days of use followed by 7 days of non-use was followed for 6 cycles. During the first two cycles of use, concentrations of cholesterol, HDL cholesterol, triglycerides and LDL cholesterol declined significantly from control levels, up to 25% for cholesterol, 28% for HDL cholesterol, 45% for friglycerides and 24% for LDL cholesterol. There were no subsequent changes with continued use. These declines are similar in direction but of lesser magnitude than those reported from clinics in other countries where pretreatment plasma levels of the same lipids are considerably higher. There was no significant change in the total cholesterol to HDL cholesterol ratio during treatment.

Adolescent↗
PubMed1981

An unrecognized neurological syndrome: sixth-nerve palsy and Horner's syndrome due to traumatic intracavernous carotid aneurysm.

An unclassified type of ophthalmoplegia, composed of sixth-nerve paresis and Horner's syndrome without facial anhidrosis, was studied in an 18-year-old woman following cranial trauma. Carotid angiography disclosed a traumatic intracavernous carotid aneurysm. According to previous anatomical reports, an important sympathetic nerve joins the sixth cranial nerve in the posterior part of the cavernous sinus. An expansive process into the cavernous sinus at this point may cause this unclassified neurological syndrome. A review of the literature and a detailed clinical study were made.

Abducens Nerve↗
PubMed1981

Congenital hepatic fibrosis in children.

Twenty-seven children with congenital hepatic fibrosis were followed for three months to 12 years. Hepatosplenomegaly, normal liver function tests, and kidney abnormalities were present in most patients, indicating that a correct diagnosis of congenital hepatic fibrosis could be made using simple clinical, biologic, and radiologic criteria. Esophageal endoscopy showed varices in 21 patients. Sixteen children underwent portal-systemic shunt surgery. Follow-up examinations did not show any impairment of liver function or any sign of hepatic encephalopathy. Cholangitis was present in only three children.

Adolescent↗
PubMed1980

Management of patent ductus arteriosus in preterm babies.

There is a higher incidence of delayed closure of the patent ductus arteriosus in premature babies with respiratory distress syndrome. From July, 1975, to December, 1977, 57 small, preterm infants with patent ductus arteriosus were diagnosed at our neonatal intensive care unit. From July, 1975, until September, 1976 (first period), 23 patients were diagnosed, and 11 underwent surgical ligation of a patent ductus arteriosus. There were 3 early deaths. From October, 1976, until December, 1977, out of a total of 34 patients with diagnosed patent ductus, 18 were treated with indomethacin, and only 3 required ligation. Our present policy for patent ductus arteriosus with respiratory distress syndrome in the premature baby is to initiate early treatment with indomethacin. If this treatment fails and the infant's status deteriorates, we perform early surgical ligation of the ductus in order to minimize the time on mechanical ventilation and lessen the chances of the development of bronchopulmonary dysplasia.

Ductus Arteriosus↗
PubMed1979

First year clinical experience with six levonorgestrel rods as subdermal contraception.

Previous clinical experience with six levonorgestrel subdermal capsules showed a very good contraceptive effectiveness and continuation rate, but with a high proportion of bleeding disturbances, particularly of increased bleeding. It was hypothesized that bleeding could be reduced by higher plasma levels of the steroid, using subdermal rods instead of capsules, as rods have been shown to have a release rate 3 or 4 times that of the capsules. Fifty volunteers were enrolled in a study of the clinical performance of 6 subdermal levonorgestrel rods. Results were compared with a previous experience with 100 volunteers who wore 6 levonorgestrel capsules for a year in the same clinic. Requirement for volunteers to enter the study were the same for capsules and rods. The proportion of women wearing 6 subdermal rods who had increased bleeding was about one half as for the women using 6 levonorgestrel capsules. On the other hand, women using rods had about twice the incidence of amenhorrea, and about four times more hypomenorrhea (4 days or less of bleeding in a 90-day period). There were no pregnancies among the rod users and the discontinuation rate for medical reasons was not higher than for capsule users in the same clinic.

Adolescent↗
PubMedDate not supplied

Nervous and ocular disorders in children with cholestasis and vitamin A and E deficiencies.

Thirteen children, aged 10 months to 20 years, presenting with chronic cholestasis from the first month of life and with low serum levels of vitamins A and/or E, have been investigated for neurological and ophthalmological symptoms. Clinical findings consisted of 4 types: peripheral neuropathy; cerebellar dysfunction; abnormalities of eye movement, and retinal degenerative changes. The results of electrophysiological and morphological studies of muscle and nerves were consistent with neurono-axonal degeneration. Electrical abnormalities of the retina, especially a decrease of the b wave of electroretinogram, appear to be the first sign of the syndrome, allowing early detection. Evidence for vitamin deficiency (E or E+A) suggests substitutive parenteral treatment in such patients.

Adolescent↗
PubMedDate not supplied

Biochemical indicators of vitamin A depletion in children with cholestasis.

Biochemical indicators of vitamin A status were measured in 24 children (1 month to 6 years old) with severe cholestasis starting early in life and in 21 children (3 months to 13 years old) with liver disease but without cholestasis. Liver vitamin A concentrations, expressed as micrograms of retinol per gram of liver (mean +/- S.D.), were 6.3 +/- 7.1 (range: 0.14 to 28) and 143 +/- 108 (range: 18 to 424), respectively, in cholestatic and non-cholestatic children. In infants less than 6 months of age, liver vitamin A values less than 10 micrograms per gm were found in 14 of 17 cholestatic children but in none of 3 non-cholestatic subjects. Plasma vitamin A values, expressed as micrograms of retinol per deciliter (mean +/- S.D.), were 23 +/- 18 (range: 3 to 62) and 46 +/- 33 (range: 14 to 125), respectively, for the two groups. Plasma retinol values less than 10 micrograms per dl were always associated with liver concentrations less than 10 micrograms per gm. Plasma retinol-binding protein was only reduced to 71% of control values in cholestatic children. The fatty acid composition of liver retinyl esters was unaffected by any condition studied. Infants with chronic cholestasis are in a precarious nutritional status very early in life relative to liver reserves of vitamin A. Plasma vitamin A values, unless less than 10 micrograms retinol per dl, are poor indicators of inadequate vitamin A status.

Adolescent↗
PubMedDate not supplied

Anti-liver-kidney microsome antibody is a marker for the rat hepatocyte endoplasmic reticulum.

Human sera, containing anti-liver-kidney microsome antibody as demonstrated by indirect immunofluorescence, were obtained from a subgroup of young patients with autoimmune chronic hepatitis. The anti-liver-kidney microsome antibody-positive sera were used to study the localization of the liver-kidney microsome antigen in hepatocytes. Immunoblot analysis of microsomal subfractions, lysosomal membranes, plasma membranes, mitochondria and purified ribosomes obtained from rat liver demonstrated that this antibody recognizes a protein of 50 kD present only in endoplasmic reticulum membranes. Immunogold labeling of ultrathin frozen sections and immunoperoxidase staining of 11 to 15 micron cryostat sections were used to detect the liver-kidney microsome antigen in rat liver tissue. The anti-liver-kidney microsome antibody binds to antigenic domains on the cytoplasmic face of smooth and rough endoplasmic reticulum membranes of hepatocytes. No labeling was observed of the Golgi apparatus, peroxisomes, mitochondria, lysosomes, nuclei or plasma membranes. Not only was the antigen recognized by the anti-liver-kidney microsome antibody specific for endoplasmic reticulum membranes, but it was also specific for the endoplasmic reticulum of hepatocytes only, since no labeling was observed in any organelle of Kupffer or endothelial cells. Therefore, the anti-liver-kidney microsome antibody can be considered as a marker for endoplasmic reticulum in rat hepatocytes.

Antigens↗
PubMedDate not supplied

Chronic active hepatitis associated with antiliver/kidney microsome antibody type 1: a second type of "autoimmune" hepatitis.

Sixty-five patients with histologically proven chronic active hepatitis of unknown cause but associated with the antiliver/kidney microsome antibody type 1, confirmed by immunofluorescence and immunoprecipitation, were selected as forming a special entity. This disease was found to be rare with a prevalence of 5/1,000,000. The female to male ratio was 8:1. The condition occurred at all ages but was most common between the ages of 2 and 14 years. In 22 of the 65 cases, the hepatitis was associated with an autoimmune disease, most commonly insulin-dependent diabetes, autoimmune thyroid disease and vitiligo. The same autoimmune diseases were present in first-degree relatives from seven families. In 36 cases, the onset of disease resembled acute viral hepatitis. Serum biochemical tests showed marked elevation in aminotransaminases and hypergammaglobulinemia. Paradoxically, serum and salivary IgA levels were often normal or low. Histologic findings were multifocal hepatic necrosis with bridging in the acute stage, and aggressive hepatitis with mononuclear cell infiltration or macronodular cirrhosis in the late stages. Serologically, apart from the presence of antiliver/kidney microsome antibody type 1, the disease was characterized by the absence of antiactin, antimitochondria and antinucleus antibodies; however, organ-specific autoantibodies were often present. The clinical course was usually severe: six patients in the acute stage presented with fulminant hepatitis, and all, except two, other patients progressed to cirrhosis. Prolonged treatment with corticosteroids and immunosuppressants was usually effective in rendering the cirrhosis inactive. The cumulative survival rate was 51% at 14 years. We propose to call this entity "anti-LKM1 chronic active hepatitis" or "autoimmune hepatitis type II" to differentiate it from classical "lupoid hepatitis" or autoimmune hepatitis type I.

Autoantibodies↗
PubMedDate not supplied

Seasonal intrathymic erythropoietic activity in trout.

Thymus glands of two salmonid species, Salmo trutta and Oncorhynchus mykiss, caught monthly throughout the year, were examined by light and transmission electron microscopy. Erythropoietic foci, consisting of both developing and mature erythroid cells, occurred in the subcapsular, inner, and outer thymic zones from April to November. We discuss the possible physiological significance of this seasonal erythropoietic activity, together with the role played by the thymic cell microenvironments and endocrine factors.

Animals↗
PubMedDate not supplied

Effects of transmission delays and noise in recurrent excitatory neural networks.

Random perturbations, referred to as noise, are omnipresent in the nervous system. We investigate how noise modifies the dynamics of the neural networks according to the delay. In this report, we examine the effect of transmission delay on both the dynamics of a single neuron receiving a recurrent excitation and the dynamics of fully interconnected excitatory networks. In the case of the single neuron with a recurrent connection, depending on the value of the delay, the discharge pattern changes from regular to multiplets. More complicated patterns appears when noise is added, and depends on both the delay and the noise intensity, but classification can be described. In certain conditions, noise reduces the synchronization, whereas in others it increases the regularity of the network activity. Finally, the same network codes the input amplitude either using mean activity amplitude coding when short delays exist, and using frequency modulation when long delays exist.

Animals↗