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Biomedical subjects

M Silva

Publications and source records attributed to M Silva.

At least 145 records · Page 8Linked to original sources
PubMed1991

[Prevalence of antibodies against hepatitis C virus (anti HCV) in different populations with chronic liver disease using the first generation test].

UNLABELLED: In order to evaluate the prevalence of antibodies IgG against the virus of hepatitis C (anti HCV) in different forms of chronic liver disease negative for virus B markers of alcoholism, we studied 148 patients (pts) divided into several groups. Group I: Composed of 35 pts. with chronic active hepatitis (CAH) with definite evidence of parenteral exposure to blood. Group II: included 39 pts. with CAH without immune markers or evidence of possible parenteral transmission. Group III: Included 37 pts. with the diagnosis of CAH of autoimmune type with positivity of antinuclear, anti smooth muscle or both antibodies with range of positivity of 1:80 or higher. Group IV: was composed of 31 pts. with the diagnosis of primary biliary cirrhosis (PBC). Finally group V included 6 pts. with an overlap syndrome between CAH and PBC. The prevalence of anti HCV in the different groups was as follows: [table: see text] Two of the pts. positive for anti HCV in group III and 1 in group IV revealed parenteral exposure to blood or blood product. CONCLUSIONS: The determinations of anti HCV in order to characterize the posttransfusional NANB chronic hepatitis is of value. Positivity of anti HCV is high in cryptogenic chronic hepatitis and rare in PBC. In CAH of autoimmune type and in the overlap syndrome the prevalence was higher than expected. The question if we are dealing with false positivity or an uncertain diagnosis of autoimmunity is raised.

Biopsy↗
PubMed1991

[Bacterial overgrowth in small intestine in patients with liver cirrhosis].

Hepatic encephalopathy, bacterial infections and endotoxemia in cirrhotic patients have been related to colonic flora. However, an abnormal small bowel bacterial content could also be implied. We investigated small bowel bacterial overgrowth (SIBO) by jejunal cultures in 14 cirrhotic patients and 5 control subjects, and indirectly by the lactulose H2 breath test in 22 patients with cirrhosis and 12 controls. SIBO was demonstrated by cultures in 64% of cirrhotic patients and 1 of 5 controls. The breath test was positive for SIBO in 45% of patients with cirrhosis and 8% of controls. No differences were noted between patients with alcoholic and non-alcoholic liver disease. According to fasting H2 breath levels, SIBO was significantly correlated with the Child-Pugh score for hepatic function (r = 0.45; p < 0.05). Also, patients with positive criteria for SIBO in jejunal cultures had worse hepatic function in comparison to cirrhotics with normal jejunal bacterial counts (p < 0.05). Thus SIBO is frequent in patients with hepatic cirrhosis and is associated with impairment in hepatic function.

Bacteria↗
PubMed1991

[Poems syndrome: review of a case].

POEMS (acronym for polyneuropathy, organomegaly, endocrinopathy, M protein and skin changes) is a very rare syndrome probably related to plasma cell dyscrasia. A 43 year old man developed a progressive symmetric sensory motor polyneuropathy 2 years before admission. Hepatosplenomegaly and sclerodermatoid skin changes were present on physical examination. A sclerotic lesion of the right femur was disclosed by radiologic examination. Serum immunoelectrophoresis demonstrated a monoclonal protein IgG-lambda pattern and the bone marrow biopsy revealed an increased plasma cell count (15%). The patient died 7 months after admission from pneumonia. A review of the literature is included.

Adult↗
PubMed1990

Efficacy, tissue distribution and biliary excretion of methyl (3R*,5S*)-(E)-3,5-dihydroxy-9,9-diphenyl-6,8-nonadienoate (CP-83101), a hepatoselective inhibitor of HMG-CoA reductase activity in the rat.

Methyl (3R*,5S*)-(E)-3,5-dihydroxy-9,9-diphenyl-6,8-nonadienoate, CP-83101, was identified as a potent competitive inhibitor of 3-hydroxy-3-methylglutaryl coenzyme A (HMG-CoA) reductase activity, inhibiting enzyme activity in vitro with an IC50 of 8.5 +/- 0.7 microM and a Ki with respect to HMG-CoA of 2.6 microM. CP-83101 also inhibited rat hepatic sterol biosynthesis by 39 +/- 7% at a dose of 100 mg/kg. [3H]CP-83101, administered orally to rats, exhibited peak plasma levels at approximately 1 hr that declined thereafter with an apparent half-time of 2-3 hr. Peak tissue levels also occurred 1 hr following oral administration of [3H]CP-83101. The decline in radioactivity in the liver, however, was considerably slower than that noted in blood, whereas the half-life in non-hepatic tissues was approximately 1 hr. Liver/blood ratios of 14, and liver/lens ratios of greater than 3000, following oral administration of [3H]CP-83101, were similar to those previously reported for other HMG-CoA reductase inhibitors, suggesting a high degree of tissue selectivity. In addition, liver/adrenal and liver/ovary ratios were approximately 1000 at all time points examined between 30 min and 24 hr following oral [3H]CP-83101 administration, indicating a high specificity for hepatic versus other steroidogenic tissues. Evaluation of intravenous versus oral administration of the water-soluble, free acid, sodium salt of [3H]CP-83101 in bile duct canulated rats indicated that approximately 20% of orally administered CP-83101 is absorbed from the gastrointestinal tract, and that absorbed CP-83101 is cleared rapidly from the plasma via the liver and from the liver via the bile. In addition, several lines of evidence suggest that CP-83101 may undergo enterohepatic recirculation. Agents of this synthetic series may thus possess advantages over other HMG-CoA reductase inhibitors with respect to tissue kinetics and specificity.

Administration, Oral↗
PubMed1990

Kinetic determination of vitamin B12 in pharmaceuticals by the continuous addition of reagent technique.

An automatic kinetic method for the determination of micro amounts of vitamin B12 in pharmaceutical samples based on the fast formation of a coloured complex between the cobalt contained by this vitamin and PAR [4-(2-pyridilazo)resorcinol] in a weakly alkaline medium and on the use of the continuous addition of reagent technique for the mixing of sample and reagent is reported. The reaction is monitored by measuring the changes in the absorbance at 510 nm characteristic of the complex formed. The linear range of the determination is 1.1-34.5 micrograms ml-1 and the relative standard deviation is 1.2%. The sample throughput is 75 h-1 (triplicate runs). The results obtained in analyses of pharmaceutical samples showed excellent correlation with nominal contents and the results of atomic absorption spectrophotometric analyses.

Cobalt↗
PubMed1990

Flumecinol, a novel inducer of testosterone 16 alpha-hydroxylation in male rats.

1. Flumecinol, a new inducer of the cytochrome P-450 monooxygenases, was studied in rats as a possible effector of liver microsomal testosterone oxidases. The drug enhanced the total content of liver cytochrome P-450 in immature and adult rats. 2. When total testosterone oxidation activity was compared in liver microsomes of treated and untreated rats, no differences in activities were observed in 60-day-old-rats, but a slight decrease was found in 35-day-old treated rats. 3. Several regio- and stereo-specific hydroxylases were modified by flumecinol administration; in 35-day-old rats only 16 alpha-hydroxylation was induced, whereas in 60-day-old rats a slight increase in 2 alpha-hydroxylation was also observed.

Aging↗
PubMed1990

[The determination of immunological parameters in splenectomized patients].

We studied 15 patients submitted to splenectomy. Humoral immunity was studied with protein electrophoresis and quantification of immunoglobulins; cellular immunity was studied by total and subpopulation lymphocyte counts and evaluation of phagocytosis. Increased levels of IgG, IgM and IgA, a decrease in circulating T-lymphocytes and an increased phagocytosis was seen after operation. These findings correlated to the presence of viral and parasitic infections postoperatively. Preoperative antipneumococcal vaccination prevented infections by this agent. Thus, appropriate preventive measures must be taken to deal with altered immunological responses after splenectomy.

Adolescent↗
PubMed1989

Vascular endothelial growth factor: a new member of the platelet-derived growth factor gene family.

Using applications of the polymerase chain reaction (PCR) technique, cDNA clones have been isolated encoding bovine vascular endothelial growth factor (VEGF), a mitogen with specificity for vascular endothelial cells. Analysis of the clones indicates that VEGF can exist in two forms, probably due to alternative RNA splicing. The amino acid sequences predicted from the clones also show that VEGF shares homologies of about 21% and 24% respectively with the A and B chains of human platelet-derived growth factor (PDGF), and has complete conservation of the eight cysteine residues found in both mature PDGF chains. The homology is not reflected in function, however, since the cell types responsive to VEGF are distinct from those responsive to homo- and heterodimers of the PDGF chains.

Amino Acid Sequence↗
PubMed1989

The effect of organotin compounds on chloride secretion by the in vitro perfused rectal gland of Squalus acanthias.

The effects of various organotins on membrane function and electrolyte transport were studied in the marine elasmobranch, Squalus acanthias. The isolated perfused rectal gland was used as a model of electrolyte transport. This gland can be stimulated to secrete chloride by atrial natriuretic peptide, veratrine, and vasoactive intestinal polypeptide although the mechanism of action of each secretagogue is different. By analysis of the inhibitory effect of an organotin in the presence of each secretagogue, the mechanism of inhibition can be inferred. Tributyltin (TBT) produced a reversible inhibition of epithelial transport at 10(-8) to 10(-7) M which resulted from inhibition of stimulus-secretion coupling in VIP-containing neurons within the gland. The transporting epithelial cells were unaffected at these concentrations. Trimethytin (TMT) produced inhibition at 10(-7) M which was not reversible and which affected primarily the transporting epithelial cells. Triethyltin and triphenyltin were without effect. The inhibitory effect of TBT and TMT was not affected by simultaneous administration of dithiothreitol. TBT also produced inhibition of oxygen consumption, Na+,K-ATPase, and proton ATPase in dispersed rectal gland cells. These results indicate that organotins are toxic to cell membrane functions which are intimately involved in the movement of electrolytes. This is the first evidence of toxicity to membrane transport functions in a marine species which is at risk from environmental exposure.

Animals↗
PubMed1989

A modular stopped-flow system for use in routine pharmaceutical analysis.

A modular stopped-flow system for routine pharmaceutical analysis is presented. It consists of an inexpensive stopped-flow module which is fitted to a spectrophotometer or spectrofluorimeter and controlled by a simple computer. The automatic technique developed with this system is suitable for the individual and simultaneous determination of various pharmaceuticals (anti-asthmatics, psychotropics, hormones, analgesics, anaesthetics and antiseptics) with satisfactory results.

Autoanalysis↗
PubMed1989

Analysis of carbofuran residues in soil by the stopped-flow technique.

A simple method for the determination of carbofuran by the stopped-flow technique and which is suitable for its routine analysis in soil samples is reported. The method was based on the coupling reaction between carbofuran phenol (the hydrolysis product of carbofuran) and diazotised sulphanilic acid to form a coloured compound, the rate of formation of which was monitored spectrophotometrically. The calibration graph was linear in the range 1-40 micrograms ml-1 (RSD, 2%) and the method was highly selective. The average recovery of carbofuran was 96.5% from soil, and less than 0.5 micrograms g-1 could be detected. A procedure for the resolution of propoxur - carbofuran mixtures of mass ratios in the range 5:1-1:10 with a precision of ca 3% is also described.

Carbofuran↗
PubMed1989

Platelet-activating factor in human luteal phase endometrium.

Platelet-activating factor (PAF; 1-O-alkyl-2-acetyl-sn-glycero-3-phosphorylcholine) is one of the most potent mediators of vascular permeability. PAF levels change in the rabbit endometrium just prior to implantation, which suggests that PAF may be a key substance transducing preimplantation embryonic signals. To study whether PAF was present in the human endometrium, and if so, to determine the cellular origin and hormonal regulation of endometrial PAF, specimens were obtained from 14 women (aged 23-42 yr) undergoing elective hysterectomy during the luteal phase of the cycle (plasma progesterone levels greater than 2 ng/ml). No specimens were taken from women with malignant uterine pathology. Stromal cells and epithelial glandular cells were separated by collagenase and DNAse digestion, and then cultured to confluence in vitro in medium 199. Radioimmunoassays of prostaglandin F (PGF) and prolactin in the culture media were used to confirm cell type and viability. PGF release into the culture medium from stromal cells was low (control 1.52 +/- 0.20 ng/ml), and unchanged by hormone treatment. In contrast, release of PGF from unstimulated glandular cells was 6.05 +/- 0.52 ng/ml, and was significantly increased (p less than 0.05) by estradiol or progesterone plus estradiol, to 12.17 +/- 1.67, and 8.60 +/- 0.81, respectively. Progesterone alone was without effect. Prolactin was secreted by stromal cell cultures, increasing steadily from 24 to 120 h. The levels in the medium were increased by progesterone. PAF activity was assessed by rabbit platelet aggregation and serotonin-release bioassays after lipid extraction and separation by thin-layer chromatography.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1989

Suppression of colonic microflora by cefoperazone and evaluation of the drug as potential prophylaxis in bowel surgery.

We evaluated the activity of cefoperazone (CPZ) on the intestinal flora in terms of its use as a single prophylactic drug in colon surgery. Twenty-four healthy male volunteers between the ages of 20 and 40 were assigned to receive either CPZ, oral neomycin-erythromycin, or no antibiotics. A mechanical bowel preparation, Golytely, was also given to each of the subjects. With intravenous CPZ, antibiotic levels in the stool ranged from less than 2 to 649 micrograms/ml and the total fecal bacterial counts dropped 3 to 4 log10 CFU/g. Higher levels of CPZ were detected in the stools when an oral dose was added, 1,446 to 5,445 micrograms/ml, and the bacterial counts were reduced maximally 4 to 6 log10 CFU/g. The combination of the oral and intravenous doses produced suppression of the microflora and high levels in blood, all with a single antibiotic.

Administration, Oral↗
PubMed1988

In vitro activity of LY146032 against gram-positive bacteria.

The activity of LY146032 (LY) was evaluated against 269 clinical isolates: 150 Staphylococcus spp. (Staph), 45 enterococci, 51 Clostridium spp., and 23 peptostreptococci. LY was compared to penicillin, metronidazole, imipenem, clindamycin, oxacillin, ciprofloxacin, vancomycin, and ampicillin. LY and oxacillin were tested against Staph by microdilution in cation-supplemented Mueller-Hinton broth (CSMHB), and in unsupplemented Mueller-Hinton broth (MHB). For LY, the MIC 90s in CSMHB were 16-32 dilutions lower. Among the Staph, the MIC 90s for LY, vancomycin, and ciprofloxacin were 4 micrograms/ml, 4 micrograms/ml, and 2 micrograms/ml respectively. The MIC 90s for enterococci by agar dilution were as follows: LY 8 micrograms/ml; ampicillin 4 micrograms/ml; imipenem 4 micrograms/ml; vancomycin 4 micrograms/ml; and ciprofloxacin 2 micrograms/ml. Clindamycin and penicillin were the most effective drugs against peptostreptococci and Clostridia spp., but LY was the most active drug against Clostridium difficile. The bactericidal activity of LY was determined by 24-hr time-kill curves in MHB. These showed a bactericidal effect against enterococci, and a bacteriostatic effect against three of four strains of Staph. Synergy was demonstrated against enterococci and Staph when LY was tested with aztreonam, ceftriaxone, or tobramycin. LY is a promising new agent against gram-positive bacteria, including methicillin resistant strains of staphylococci and enterococci.

Anti-Bacterial Agents↗
PubMed1988

Nutrition-related alterations in liver microsomal testosterone hydroxylases.

The oxidation products of testosterone formed by liver microsomes from normal-fed and protein-energy malnourished male rats have been analysed by HPLC. Microsomes from normal-fed rats oxidized testosterone at a rate of 4.52 nmol/min/mg protein. The major products formed were: 6 beta-, 7 alpha- and 16-alpha-hydroxytestosterone; these three metabolites represented 65% of the total testosterone metabolism. Microsomes from protein-energy malnourished rats oxidized testosterone at a reduced rate of 2.03 nmol/min/mg protein. The major product formed was 7 alpha-hydroxytestosterone, which accounted for 43% of total testosterone oxidation. Microsomes from protein-energy malnourished rats showed a CO-reduced cytochrome P-450 spectra with a maxima at 452 nm, and a 38% decrease in the total content of cytochrome P-450. Some testosterone hydroxylases were drastically affected by protein-energy malnutrition but others, such as 7 alpha-hydroxylase, remained unchanged. The present results suggest that nutritional status can modify the relative amounts of individual cytochrome P-450 isozymes, thus explaining the observed changes in several testosterone hydroxylases. Protein-energy malnutrition seems to be an excellent tool with which to obtain a microsomal fraction containing predominantly P-450 isozymes, which are probably involved in key mono-oxygenations of physiological substrates.

Animal Nutritional Physiological Phenomena↗