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Biomedical subjects

R Silva

Publications and source records attributed to R Silva.

At least 73 records · Page 4Linked to original sources
PubMed1997

A peptide released by pepsin from kininogen domain 1 is a potent blocker of ANP-mediated diuresis-natriuresis in the rat.

A 20-amino acid peptide, KYEIKEGDCPVQSGKTWQDC (PU-D1), released by pepsin hydrolysis of LMW kininogen domain 1 was tested for its ability to antagonize the diuretic and natriuretic effect of ANP(103-125) in anesthetized rats. A single dose of 10.8 or 21.6 pmol (25 or 50 ng) PU-D1 given intravenously or into the duodenal lumen suppressed the diuresis-natriuresis induced by 209 pmol (500 ng) ANP by 43% to 59% and 69% to 96%, respectively. None of the doses tested (2.16 to 432 pmol, 5 ng to 1 microg) modified systemic blood pressure. Strikingly, a single IV dose of 10.8 pmol PU-D1 blocked the action of ANP for more than 3 hours. ANP blockade by PU-D1 was annulled completely by the bradykinin (BK) B2 receptor inhibitor Hoe 140. On a molar basis, PU-D1 is more effective than BK and kinins of 15, 16, and 18 amino acids for blocking the ANP-mediated diuresis-natriuresis. As with BK and other kinins, the inhibitory effect of Pu-D1 on ANP is obtained only within a small range of picomol doses. A single dose of 2.16 or 4.32 pmol PU-D1 or 47 pmol (50 ng) BK is ineffective against ANP if injected alone. However, when both substances are administered concomitantly at these subthreshold doses, they totally suppress ANP-induced diuresis-natriuresis. These results raise the question of whether PU-D1, released from kininogen domain 1, either alone or associated with BK, may interact with ANP in the regulation of urinary water and electrolyte excretion in physiological and pathological conditions.

Amino Acid Sequence↗
PubMed1997

Effect of bilirubin on erythrocyte shape and haemolysis, under hypotonic, aggregating or non-aggregating conditions, and correlation with cell age.

The effect of unconjugated bilirubin on the morphology and haemolysis of human erythrocytes was accomplished under distinct incubation conditions: (i) hypotonic medium, with bilirubin concentrations ranging from 1 x 10(-9) to 1 x 10(-4) mol l-1; (ii) isotonic medium, with 171 mumol l-1 bilirubin, in the absence of albumin (aggregating conditions), using non-separated and age-fractionated erythrocytes; (iii) isotonic medium, with 171 mumol l-1 bilirubin, in the presence of a surplus of human serum albumin (non-aggregating conditions), and using sulfisoxazole as a bilirubin displacer (bilirubin/albumin and sulfisoxazole/ albumin molar ratios of 0.5 and 4.0, respectively). Our data showed that low concentrations of bilirubin (1 x 10(-7) to 1 x 10(-5) mol l-1) protect against hypotonic haemolysis and induce crenation, while higher bilirubin concentrations induce haemolysis and lead to membrane disruption. When aggregating conditions were used, these phenomena were reproduced, the younger cells being significantly more susceptible to crenation while the older erythrocytes showed increased susceptibility to haemolysis. In non-aggregating conditions, haemolysis was virtually absent, though crenation was evident. Based on the above observations we conclude that the first step of erythrocyte bilirubin toxicity is crenation due to an expansion of the outer membrane leaflet by bilirubin mono-anion location. This effect is more evident in younger cells and explains the protection against the hypotonic haemolysis. Insertion of bilirubin deeper into the bilayer, facilitated by higher concentrations (> or = 1 x 10(-4) mol l-1) and cell age, produces an unstable situation, where bilirubin acid aggregation is apparently the main cause for haemolysis and cell destruction.

Bilirubin↗
PubMed1997

[Surgical treatment of diffuse hyperthyroid goiter. Experience at a hospital in Valdivia, Chile].

BACKGROUND: The choice of medical, radiation or surgical therapy for hyperthyroid diffuse goiter is still empirical. AIM: To report a retrospective analysis of the surgical treatment of hyperthyroid goiter in a Regional Hospital in Chile. PATIENTS AND METHODS: The charts of 64 patients, 54 female, aged between 15 and 57 years old, operated between 1985 and 1995 were analyzed. RESULTS: The indication for surgical treatment was failure of medical treatment in 59 patients and a big goiter causing mechanical compression in 3 patients. A subtotal thyroidectomy was done after an abbreviated surgical preparation. The mean weight of the resected glands was 65.9 g. Four patients had transient hypocalcemia and 4 had surgical wound seromas. After a mean follow up of 31 months, 77% of patients remain euthyroid, hyperthyroidism relapsed in 13.1% and 10% became hypothyroid. CONCLUSIONS: Surgical treatment of hyperthyroid goiter is safe but the percentage of hyperfunction relapse is high.

Adolescent↗
PubMed1996

The triglyceride lowering effect of fish oils is affected by fish consumption.

We investigated the efficacy of fish oils in Portuguese patients with hypertriglyceridaemia and mixed hyperlipidaemia, and the influence of fish consumption on the triglyceride lowering capacity of fish oils. Forty patients participated in this double-blind study, consisting of a 4-week dietary or wash-out baseline period after which patients were randomly assigned to receive either 12 fish oil capsules (3.6 g/day of omega 3) or similar 12 soya oil capsules per day for a period of 2 months. There were no statistically significant changes of total, HDL or LDL-cholesterol, and triglycerides. Nevertheless, triglycerides increased 19.9% with soya oil and decreased 27.8% with fish oils. Also, there was an inverse relationship (rho = -0.352) between fish consumption and fish oils effect on triglycerides, and the triglyceride lowering with fish oils increased (from 27.8% to 44.4%), reaching borderline significance, if we excluded patients consuming one or more meals with fish per day. Glucose increased 11% (P = 0.0047) with fish oils. These findings suggest that the triglyceride lowering effect of fish oils is affected by fish consumption, and confirm that fish oils increase blood glucose levels in diabetics and non-diabetics.

Adolescent↗
PubMed1996

A fragment of human kininogen containing bradykinin blunts the diuretic effect of atrial natriuretic peptide.

A synthetic 15 aminoacids kinin, named PU-15, is able to block the diuretic natriuretic action of Atrial Natriuretic Peptide (ANP). The structure of PU-15 is Met-Lys-Arg-Pro-Pro-Gly-Phe-Ser-Pro-Phe-Arg-Ser-Ser-Arg-Iso, having the aminoacid sequence of a fragment of human kininogens. The increase in the urinary excretion of sodium, potassium, and water, elicited by a bolus of 0.5 microg of ANP in anesthetized rats, is blocked by PU-15 (100-150 ng) given either intravenously 3 min before ANP injection, or injected intraperitoneally or in the duodenal lumen, 40 min before ANP. This ANP blockade, which mimics the action of pepsanurin, is only obtained with doses of PU-15 in a narrow range around 100 picomol/rat, and do not modify blood pressure. Larger doses, 2- to 8-fold the effective dose, either do not change the response to ANP or raise the excretion of sodium and water. The administration of HOE-140, a bradykinin B2 receptor blocker, prior to PU-15, completely abolishes the anti-ANP action of PU-15. These findings lend support to the proposal that kinins released from the intestinal tract during prandial period can modulate renal excretory function.

Animals↗
PubMed1996

[Medullary cancer of the thyroid. Experience at the Hospital de Valdivia].

BACKGROUND: Medullary carcinoma of the thyroid is an infrequent type of thyroid tumor. AIM: To retrospectively study all cases of medullary carcinoma of the thyroid diagnosed at a regional hospital. PATIENTS AND METHODS: The charts and pathological studies of eight patients with medullary carcinoma of the thyroid, among 75 with thyroidal cancer, were reviewed. RESULTS: Solitary nodules were the presenting sign in seven patients and cachexia in one. Five patients were subjected to total thyroidectomy, five to cervical lymph node dissection and four to complementary radiotherapy. Pathological diagnosis was made with the surgical piece in seven patients and by aspiration cytology in one. Five of the eight patients are alive after 50 months of follow up as a mean, one patient with bone metastasis. CONCLUSIONS: The small sample size precludes conclusions on the prognosis and treatment of the disease.

Adolescent↗
PubMed1995

Cues to the assessment of affects and moods: speech fluency and pausing.

Clinicians' rating of the negative syndrome of schizophrenia are highly correlated with the rate and duration of the patient's pauses. To test the degree to which pausing provides the cue for clinicians' impressions we selected audio recordings of interviews with schizophrenic patients who showed moderate levels of negative signs and, through the use of a computerized digital editor, transformed the recordings by either doubling or halving the duration of all of the patient's pauses. Other aspects of the patients' speech were unchanged. Ratings of flat affect were changed by the editing: reduced pause samples were seen as less flat and increased pause samples as flatter. Ratings of mood were not significantly changed. These results suggest that neuropsychological factors that interfere with fluent speech may play a role in the pathogenesis of the negative syndrome. In addition, the edited tapes provide helpful materials for training clinicians to assess moods and affects.

Adult↗
PubMed1995

[Alcohol consumption and glomerulonephritis caused by IgA mesangial deposits. (Berger's disease)].

Alcohol ingestion is considered as a possible pathogenic agent for Berger's disease, since Iga mesangial deposits have been described in liver cirrhosis. Aiming to assess this issue, 28 patients with Berger's disease (BD) and 40 patients with other glomerulopathies (NBD) were subjected to an enquiry about alcohol ingestion. Data was corroborated with 21 close relatives of BD patients and 34 relatives of NBD patients. No differences were observed in reported alcohol intake between BD patients and their relatives, however relatives of NBD patients underestimated their alcohol intake. No differences in alcohol intake, either self-reported or reported by relatives, were observed between BD and NBD patients. It is concluded that no differences in alcohol intake were observed between patients with Berger's disease and subjects with other glomerulopathies.

Adolescent↗
PubMed1995

[Endoscopic surgery in ectopic pregnancy. Analysis of 105 cases].

A report on 105 cases of ectopic pregnancy resolved via endoscopy is presented. Surgical techniques for total salpingectomy (82), salpingotomy (11), tubal expression (6), partial salpingectomy (3), partial ooforectomy (2) and anexectomy (1) is described. The excellent postsurgical recovery and low incidence of complications are depicted, as well as the growing percentage of ectopic pregnancies resolved endoscopically in our Department.

Adult↗
PubMed1994

The blood-retinal barrier in diabetes during puberty.

OBJECTIVE: To assess the alteration of the blood-retinal barrier in patients with type I diabetes during puberty. DESIGN: A 7-year prospective study evaluated retinal changes occurring in diabetic children during puberty. Patients between the ages of 10 and 20 years underwent annual ophthalmologic examinations that included fluorescein angiography and vitreous fluorophotometry. SETTING: Clinical research facility. PATIENTS: Fifty-seven diabetic children met preset eligibility criteria. During the study, 241 ophthalmologic examinations were scheduled and 210 (87.1%) were performed. MAIN OUTCOME MEASURE: Vitreous fluorophotometry penetration ratio (VFPR) was used to indicate blood-retinal barrier permeability. RESULTS: No sign of retinopathy was detected before puberty (age 13 years for boys and 11 or 12 years for girls). The prevalence of retinopathy in the 4 years immediately after puberty was 6%. In the next 4 years, the prevalence was 29.6% (P = .0003). When all VFPRs were correlated with age, and data for male and female patients were analyzed separately, we found that the lowest VFPRs occurred at the expected time of puberty. When patients were paired by gender and duration of diabetes, there was a significant difference between VFPR values before and after puberty (P = .03). Also, a progressive deterioration of the blood-retinal barrier became apparent when only VFPR values after puberty were considered. CONCLUSIONS: These results support the view that the blood-retinal barrier remains stable until puberty, achieving a maximum of efficiency and protection. A progressive decline then begins, suggesting that this period of growth is associated with factors that, under the influence of diabetes, contribute to the progressive damage of the blood-retinal barrier.

Adolescent↗
PubMed1994

[Liver cirrhosis and pregnancy].

A clinical case of a woman 25 year old with Laennec's cirrhosis at 18th, week of gestation was admitted in our hospital. In the 30th week a cesarean section was performed, resulting a healthy infant. The infrequency relationship between pregnancy and cirrhosis is discussed an a review of the literature is presented.

Adult↗
PubMed1994

[Digestive process and regulation of renal excretory function: pepsanurin and prokinin inhibit the natriuretic peptide diuretic action].

In order to clarify the blunting effect of peptides released by pepsin from blood plasma on ANP diuretic action, two prokinins designated PU-18 and PU-16 were tested. Both of them were able to inhibit in nanomolar doses the diuretic-saluretic action of 0.5 ug i.v. bolus of ANP given to anesthetized rats either by intravenous route or introduced in the duodenal lumen. PU-16 in doses of 0.5 and 1 ug were able to reduce in 72 and 96.5% respectively the natriuresis induced by 0.5 ug intravenous bolus of ANP. The data support the hypothesis that prokinins liberated in the digestive tract, could be physiological factors involved in hydrosaline homeostasis, moderating the ANP mediated increase of water, Na and K excretion during digestion.

Amino Acid Sequence↗
PubMed1994

A Tcl/Tk based graphical interface to medical and administrative information.

FELIX is an front-end application processor, with an open systems back-end, that provides a uniform and intuitive interface to clinical and administrative information. It consists of an information browser, three clinical applications, and three management applications. FELIX was developed in a community hospital environment, but has conceptual and technical roots in medical informatics and the Internet.

Computer Graphics↗
PubMed1994

[Diffuse hyperthyroid goiter associated with occult papillary carcinoma of the thyroid. Report of 2 cases].

The association of diffuse hyperthyroid goiter and thyroid cancer is rare and interesting, considering that both diseases affect the same organ but have different pathogenesis and prognosis. We report two patients that consulted for diffuse hyperthyroid goiter and were subjected to a subtotal bilateral thyroidectomy due to antithyroid drug failure. Pathological study revealed the coexistence of diffuse gland hyperplasia and a papillary thyroid carcinoma of less than 7 mm phi. In both cases, the thyroid remanent was ablated with radioactive iodine during the postoperative period and thyroid substitution was started.

Adult↗