Search PubMed⌕ Search

Biomedical subjects

M Silva

Publications and source records attributed to M Silva.

At least 109 records · Page 6Linked to original sources
PubMed1995

Transforms of the computerized patient record data model: from transactions to analytical processing.

The design of Computerized Patient Record databases needs to be different depending on whether the focus of the database is transaction processing or analytical processing. Transaction processing includes the operational use of databases for single patient update during clinical encounters. Analytical processing includes cross-patient querying for research or clinical management. These different design needs are defined. A case study is presented for the methodology that transforms transaction databases to analytical ones. The resulting analytical design is argued to be successfully evaluated according to specific criteria of useability and maintainability. This methodology is easily replicated in any relational database environment.

Computer Systems↗
PubMed1995

[Diagnostic efficacy of albumin gradient in different causes of ascitis].

The aim of this study was to compare the serum-ascites albumin gradient (GS-A) to the transudate-exudate concept in the classification of ascites. The second objective was to analyze the predictive value and efficacy of GS-A, ascites total protein, LDH, Ratio and ascites cholesterol in patients with liver disease and malignant ascites. For this purpose we studied prospectively 98 patients (in prospective form). The transudate-exudate concept classified correctly the causes of ascites only in 65.6% of the patients. In contrast, the GS-A did it 95.7% of the patients. In differentiating ascites caused either by chronic liver disease or by malignancy, the tests with best efficacy were cholesterol (98%), (predictive value 97%) and GS-A efficacy 94% (predictive value 94%). We conclude that GS-A was better than the traditional transudate-exudate concept in classification of ascites. The test with the best efficcacy separating ascites caused by chronic liver disease or by malignancy was the ascites cholesterol.

Adult↗
PubMed1994

Scavenging of reactive oxygen species by silibinin dihemisuccinate.

Silibinin dihemisuccinate (SDH) is a flavonoid of plant origin with hepatoprotective effects which have been partially attributed to its ability to scavenge oxygen free radicals. In the present paper the antioxidant properties of SDH were evaluated by studying the ability of this drug to react with relevant biological oxidants such as superoxide anion radical (O2-), hydrogen peroxide (H2O2), hydroxyl radical (HO.) and hypochlorous acid (HOCl). In addition, its effect on lipid peroxidation was investigated. SDH is not a good scavenger of O2- and no reaction with H2O2 was detected within the sensitivity limit of our assay. However, it reacts rapidly with HO. radicals in free solution at approximately diffusion-controlled rate (K = (1.0-1.2) x 10(10)/M/sec) and appears to be a weak iron ion chelator. SDH at concentrations in the micromolar range protected alpha 1-antiproteinase against inactivation by HOCl, showing that it is a potent scavenger of this oxidizing species. Luminol-dependent chemiluminescence induced by HOCl was also inhibited by SDH. The reaction of SDH with HOCl was monitored by the modification of the UV-visible spectrum of SDH. The studies on rat liver microsome lipid peroxidation induced by Fe(III)/ascorbate showed that SDH has an inhibitory effect, which is dependent on its concentration and the magnitude of lipid peroxidation. This work supports the reactive oxygen species scavenger action ascribed to SDH.

Animals↗
PubMed1994

Prolonged and effective blockade of tumor necrosis factor activity through adenovirus-mediated gene transfer.

A chimeric protein capable of binding and neutralizing tumor necrosis factor (TNF) and lymphotoxin was expressed in mice transduced with a replication-incompetent adenoviral vector into which a TNF inhibitor gene had been engineered. Within 3 days following the injection of 10(9) infectious particles, the TNF inhibitor concentration exceeded 1 mg/ml of plasma; this level of expression was maintained for at least 4 weeks, and detectable TNF inhibitory activity was measured 6 weeks after injection of the recombinant virus. Introduction of the artificial gene produced a phenotypic effect comparable to homozygous deletion of the 55-kDa TNF receptor, in that animals were rendered highly susceptible to infection by Listeria monocytogenes, whereas control animals receiving a replication-incompetent virus coding for beta-galactosidase were capable of resisting Listeria challenge. Adenovirus-mediated transfer of a gene encoding a TNF inhibitor offers a practical means of imposing effective, long-term blockade of TNF activity in vivo for investigational and therapeutic purposes.

Adenoviridae↗
PubMed1994

Improved automatic kinetic method for the determination of various corticosteroids.

Two reaction-rate methods for the determination of corticosteroids at the micromolar level were developed. The methods are modifications of the widely used Blue Tetrazolium and Porter-Silber reactions which are employed for the automatic kinetic determination of corticosteroids using the continuous-addition-of-reagent (CAR) technique. The CAR technique avoided all technical problems typically associated with these reactions such as long incubation at high temperatures, high blank values, and turbidity. On the basis of its analytical figures of merit, the Blue Tetrazolium method was chosen; it allows corticosteroids to be determined at concentrations from 2.7 x 10(-6) to 1.9 x 10(-4) M at a rate of 25 samples/h (triplicate analyses) with an root mean square deviation of ca. 3%. The proposed method was evaluated in recovery experiments and analyses of commercially available formulations.

Adrenal Cortex Hormones↗
PubMed1994

Naturally acquired infections with Leishmania enriettii Muniz and Medina 1948 in guinea-pigs from São Paulo, Brazil.

Two domestic guinea-pigs (Cavia porcellus), bought in Pinheros, São Paulo State, Brazil, were taken by their owners to a farm in the rural district of Capão Bonito, close to the Atlantic Forest, São Paulo, where they both developed tumour-like and ulcerating lesions on the ears. The causative agent was identified as Leishmania (L.) enriettii, based on biological characters and isoenzyme profiles. Sources of the parasite in wild mammals, and the possible sandfly vector species are discussed.

Animals↗
PubMed1994

Detection of hepatitis C virus RNA in hemodialysis patients.

The clinical significance of the high prevalence of antibodies to hepatitis C virus (HCV) in dialysis patients remains undefined. In order to assess the relationship between seropositivity and potential infectivity, 63 patients undergoing maintenance hemodialysis were evaluated between April and May 1990. The mean duration of maintenance hemodialysis was 45 mo (range, 13 to 144). Eighty-two percent (52 of 63) had received blood transfusions, and 16% (10 of 63) had a history of iv drug abuse. Serum samples were analyzed by HCV-cDNA polymerase chain reaction; antibodies to HCV structural (core) and nonstructural regions NS3 and NS4 were determined by enzyme immunoassay. Specimens repeatedly reactive for anti-HCV and HCV-RNA-positive samples were tested by HCV MATRIX dot immunoblot assay and HBV-DNA PCR. Twenty-five percent (16 of 63) were anti-HCV-positive. Of the 16 anti-HCV-positive patients, HCV-RNA was detected in 5 (31%) with the NS3 primers and in 12 (75%) with 5'-noncoding primers. Among the anti-HCV-negative patients, HCV-RNA was detected in 2 (4.3%) of 47 patients. Eleven of the 18 patients with HCV infection (anti-HCV and/or HCV-RNA-positive) had evidence of additional present or past viral infections (human immunodeficiency virus and/or hepatitis B virus). In summary, HCV-RNA is present in at least 75% of anti-HCV-positive patients, suggesting that they may be infectious. The detection of HCV-RNA in anti-HCV-negative patients may indicate early or chronic HCV infection not detected by current antibody assays or the inability of these patients to mount or sustain a significant antibody response.

Adult↗
PubMed1994

[Evaluation of commercial kits used for Chagas disease diagnosis in blood banks in Chile. II. Routine application].

Aiming to study the applicability and reproducibility of four commercial kits used for the serological detection of Chagas disease (Chagatest-Inst Invest Paraguay, Ortho Chagas, Abbott Chagas (ELISA tests) and Estabilgen Hemo Chagas (indirect hemagglutination test)), a comparative serological study was performed in 256 sera samples coming from a highly endemic area, 249 samples from a low endemic area, 180 reference sera and 2264 samples coming from three blood banks. Specificity of the kits was excellent and sensitivity ranged from 60 to 100%. The indirect hemagglutination test has the lower sensitivity. Some disagreements in the results were observed in the three blood banks, probably due to an unsatisfactory reactive management. We conclude that ELISA tests should be recommended for routine detection of Chagas disease and that for this purpose, a net of laboratories under the direction of a national reference center should exist. This center should assess new commercial products, train technicians and supervise the laboratories.

Blood Banks↗
PubMed1994

[Isonitrile (sestamibi) as a valid alternative to thallium 201 for myocardial perfusion studies].

OBJECTIVE: SestaMIBI is a new technetium labeled radiopharmaceutical agent approved for myocardial perfusion studies. In the present work the authors analyzed the accuracy of this agent on the study of ischemic heart disease. CONCEPTION: The present paper was made considering the results of four previous studies around defined goals performed by the same research group. SETTING: Cardiology and Nuclear Medicine departments in a general hospital. RESULTS: Planar studies: global sensitivity for the diagnosis of ischemic heart disease was 100% and specificity of 67%. Tomocintigraphic studies and segmentary analysis of IHD: the accuracy for stenosis involving the left anterior descending artery was of 80%, 91% for the right coronary artery and 67.2% for left circumflex artery. Planar studies versus tomocintigraphy--SPECT (comparative study in the same population): global sensitivity of 86% for planar method and 97% for "SPECT". In patients with single vessel disease the results are also better with "SPECT" (75% vs 94%). In this series the presence of rest perfusion defects is frequent. In 75% was possible to correlate them with a significant lesion over the related coronary artery. The positive predictive value of this finding is of 92% for the lesions on the left coronary artery, 100% for left cincumflex and 59% for the right coronary artery. CONCLUSIONS: 1. The SestaMIBI is an excellent radiopharmaceutical agent for myocardial perfusion studies. 2. The accuracy of this agent for diagnosis of ischemic heart disease is quite good with a high sensitivity and specificity values. This conclusion is also valid for those patients with single vessel disease. 3. Scintigraphic studies performed with planar acquisition provide good quality images. Nevertheless tomoscintigraphy (SPECT) is more accurate namely in patients with single vessel disease. 4. In the present state of the art and regarding our results we can conclude that is too early for considering SestaMIBI like and agent for viability studies.

Coronary Disease↗
PubMed1994

[Laparoscopic cholecystectomy. 1203 cases with ultraselective cholangiography].

We present our experience at the University of Chile Hospital with 1203 cases of laparoscopic cholecistectomy between April 1991 and July 1993. In only 36 patients ultraselective cholangiography was performed. In 88 cases an endoscopic cholangiography was performed prior to surgery because of suspicion of choledocolithiasis. In 31 of them choledocolithiasis was demonstrated, and was successfully treated by papilotomy in 30 of them. In 5.8% of cases coversion to open surgery was necessary: 1.4% in chronic cholecystitis, 13% in acute cholecystitis and 39% in cases with fibrosis and esclerosis of gallbladder with or without biliary digestive fistula. The intraoperative cholangiography has been advocated as a manner to prevent the common duct injury. In spite of the small number of cases operated on with cholangiography, we haven't seen serious injuries of biliary tract; a carefully disection, as far away as possible of the common duct, is the best way to prevent iatrogenic lesions. Postoperative morbidity was present in 15 cases, 8 of them required a new operation. Two patients died.

Adolescent↗
PubMed1994

The standard data model approach to patient record transfer.

This paper develops an approach to electronic data exchange of patient records from Ambulatory Encounter Systems (AESs). This approach assumes that the AES is based upon a standard data model. The data modeling standard used here is IDEFIX for Entity/Relationship (E/R) modeling. Each site that uses a relational database implementation of this standard data model (or a subset of it) can exchange very detailed patient data with other such sites using industry standard tools and without excessive programming efforts. This design is detailed below for a demonstration project between the research-oriented geriatric clinic at the Baltimore Veterans Affairs Medical Center (BVAMC) and the Laboratory for Healthcare Informatics (LHI) at the University of Maryland.

Computer Communication Networks↗
PubMed1994

Central catheters for hemodialysis: a six month experience of 103 catheters.

UNLABELLED: A prospective study was done during a six-month period to evaluate number, function, difficulties of placement and immediate and late complications of central venous catheters for hemodialysis. One hundred and three catheters were placed, 78 double lumen and 25 single lumen, using Seldinger technique. The places of implantation were: right subclavian in 79, left subclavian in 13, right jugular in 8 and 3 in the right femoral vein; 62 were first catheters. We needed a mean of 2 punctures to enter the goal vein, and in 4 the place of implantation had to be changed. Catheters remained in place for a mean of 21 days. Six catheters were lost to follow-up. Immediate complications were 2 hemothorax, 3 punctures of the artery and 3 malpositioned catheters. Late complications were 12 local infections, 7 associated with sepsis. Twenty catheters occluded but removal was only necessary in 10. There was no statistic difference in incidence of complications between single lumen and double lumen catheters (X2). CONCLUSIONS: 1. Percutaneous central venous catheters is a simple and safe technique to obtain temporary vascular access for hemodialysis. 2. Double lumen catheters have no higher rate of complications than single lumen.

Carotid Artery Injuries↗
PubMed1993

Effects of naloxone treatment on memory-enhancing properties of post-training administration of substance P.

The present study investigated the effects of post-trial systemic injections of the neurokinin substance P (SP) on inhibitory avoidance learning in rats treated with naloxone before conditioning and/or test trials. Rats were trained in a step-down or uphill inhibitory avoidance task and tested 24 h later. The animals received, 30 min before training and/or testing an i.p. injection of saline or naloxone (Nx) at doses of 0.5; 1.0; 5.0 or 50 mg/kg. Immediately after training they were administered SP 50 micrograms/kg or vehicle. Animals that received Nx both before conditioning and test trials (5.0 and 50 mg/kg), in combination with SP, showed better test performance for the uphill and step-down avoidance then those treated only with SP. Nx administered only before training (5.0 and 50 mg/kg) or before test (0.5 to 50 mg/kg) reduced the effects of SP. These data are discussed in terms of the possibility that Nx produces a state-dependent learning when combined with SP.

Animals↗