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Biomedical subjects

G Vargas

Publications and source records attributed to G Vargas.

At least 55 records · Page 3Linked to original sources
PubMed1983

Diarrhea associated with rotaviruses, enterotoxigenic Escherichia coli, Campylobacter, and other agents in Costa Rican children, 1976-1981.

Rotaviruses, enterotoxigenic Escherichia coli, Salmonella, Shigella, and parasites were investigated in outpatient diarrheic children, and in hospitalized diarrheic and non-diarrheic children, between January 1976 and June 1979. In outpatient cases studied within 4 days of onset of symptoms, rotaviruses were the most common agents (45.3%); E. coli heat-stable enterotoxin ranked second (13.4%); Shigella was third (8.1%); Salmonella was fourth (7.3%). In 63.2%, one or more enteric agents were detected. In hospitalized non-diarrheic children, asymptomatic shedding of pathogens was rarely observed. A later survey of outpatient diarrheic children revealed Campylobacter fetus jejuni in 8%. In 5.5 years of observation rotaviruses were endemic with excess frequency in the dry and cooler months of December and January. The excess occurrence of bacterial pathogens did not coincide with that of rotaviruses.

Campylobacter Infections↗
PubMed1979

Bilateral bleb excision through median sternotomy.

We believe that when the indications for operation for spontaneous pneumothorax are met, the procedure of choice is bilateral resection of apical blebs and pleural abrasion through a median sternotomy. This approach allows easy access to both lungs and pleural spaces for a condition that is bilateral 100 per cent of the time. The operative morbidity is minimal and it essentially eliminates both ipsilateral and contralateral recurrence of pneumothorax with an operation that is of lesser rather than greater magnitude.

Adolescent↗
PubMed1975

Electrophysiologic effects of isoproterenol on cardiac conduction system in man.

The effects of isoproternol (ISOP) on the functional properties of the A-V conduction system were studied in 16 patients using His-bundle recordings and the atrial extrastimulus technique. In all patients, ISOP at an infusion rate of 1 mcg. per minute resulted in sinus acceleration and enhancement of A-V nodal conduction, but had no effect on His-Purkinje conduction time. ISOP significantly decreased both functional and effective refractory periods of the A-V node. The relative refractory period of the His-Purkinje system decreased by a small amount in five patients in whom the parameter could be compared before and after the drug.

Adult↗
PubMed1975

Evaluation of the skin test for hookworm as an epidemiological tool.

The usefulness of a skin test with larval Necator americanus antigen for assessment of hookworm prevalence was evaluated in an endemic area of Costa Rica. In comparison with standard coprologic techniques employed to survey the population, the skin test detected 83% of infections, showing a fairly satisfactory sensitivity. The overall specificity of the test was 50%, i.e., random. No correlation was found between skin reactivity and hookworm burden. The sensitivity of the test increased moderately with age, but its specificity decreased significantly at the same time. False positive reactions were more numerous among persons formerly infected with hookworm who had been negative for as long as 5 years. There was an indication of cross reactivity with intestinal nematodes other than hookworm. The test was used to detect hookworm infected persons in the community for selective treatment, in comparison with mass treatment of all the people in another village. The selective administration of an anthelminthic drug to only skin test positive persons did not achieve the same drop in community hookworm prevalence as did the indiscriminate treatment of the whole population.

Adolescent↗
PubMedDate not supplied

Capillary zone electrophoresis determination of thyreostatic drugs in urine.

In this work, a new capillary zone electrophoresis (CZE) method has been developed for the analysis of thyreostatic drugs (TD) such as methylthiouracil (MTU), propylthiouracil (PTU), and thiouracil (TU) in urine specimens. An untreated fused-silica capillary tube (75 microns i.d., 57 cm total length, 49.5 cm length to the detector) was used in all of the experiments. Optimal conditions were found using 50 mM borate buffer, pH 7.6, applied voltage 15 kV, 25 degrees C, and 30 sec of hydrodynamic injection. UV detection at 276 nm was employed. Ethylacetate extraction of the compounds was made before the analysis of each urine sample. An electrostacking procedure to increase the sensitivity was applied. The method developed was used for the analysis of several thousands of samples as part of a veterinary control procedure (Institute for State Control of Veterinary Biological and Medicaments, Brno, Czech Republic). The following detection limits were reached: 0.3 ppm (PTU and MTU) and 0.5 ppm (TU). The standard deviation for PTU, MTU, and TU determination was 1.12, 0.98, and 3.8% rel., respectively.

Antithyroid Agents↗
PubMedDate not supplied

Determination of drugs used as anti-Parkinson's disease drugs in urine and serum by capillary electrophoresis.

A new capillary electrophoresis method to determine simultaneously eight of the most important anti-Parkinson's disease compounds has been developed. The generic names of the drugs studied are benactyzine (BA), trihexyphenidyl (TP), fenpiverin (FP), diphemin (DF), scopolamine (BL), adiphenine (TS), diethylaminoethylester 1-phenylcyclopentane-1-carboxylate (EKK), and diethylaminoethylester tetramethoxydiphenylacetate (EKO). An untreated fused-silica capillary tube (75 microns i.d., 57 cm total length, 49.5 cm length to the detector) was used with detection at 190 nm. The optimal separation conditions were 50 mM phosphate buffer (pH 2.7) with 7 mM-beta-cyclodextrin, electrokinetic injection for 15 sec at 5 kV, temperature 25 degrees C, and 15-20 kV separation voltage. Complete separation of all compounds was achieved in less than 16 min. The procedure was applied for the determination in urine and serum. The limits of detection (LOD, S/N = 3) for serum were 209 (FP), 234 (EKO), 168 (DF), 182 (BA), 168 (TP), 220 (BL), 174 (TS), and 163 (EKK) ppb. The method can be used for the therapeutic drug monitoring of these central active cholinolytics in clinical laboratories.

Antiparkinson Agents↗
PubMedDate not supplied

[Diagnostic laparotomy in the child under 12 with Hodgkin's disease].

Twenty-eight children with Hodgkin's disease were followed between 1971 to 1978. Patients were grouped at diagnosis by clinical staging (C.S.) I and II (60%) and III and IV (40%). All patients were laparotomized and splenectomized and multiple node gland biopsy were taken in order to classify them in anatomopathological stages (A.P.S.) and to administer treatment according to a local protocol. No surgical complications were seen and in 10 patients (36%), infiltration of spleen, lymph nodes and other organs were found at surgery which changed their initial clinical stage to a more advanced stage. Then patients (36%) presented 12 episodes of viral infections, during the first years after splenectomy, and 9 bacterial infectious complications mainly between 2 to 4 years after surgery. All patients with A.P.S. I and II are alive and in complete remission, without treatment and with a mean survival time (M.S.T.) of 32 months. M.S.T. in patients with A.P.S. III A has been 63 months and two out of six have died from tumor dissemination and septicemia. M.S.T. in patients A.P.S. III B and IV has been 57 months and 3 out of 11 have died all from dissemination of their disease. Dissemination of the disease, splenectomy and immunologic depression from therapy are important factors to be evaluated when laparotomy is performed in children with Hodgkin's disease.

Child↗
PubMedDate not supplied

[Results of combined therapy in rhabdomyosarcoma in children].

In a study of rhabdomyosarcoma in children, 16 cases were treated and followed since 1971. Eight patients were staged I and II A and presented a mean survival time of 52 and 21 months respectively, whereas the remaining 8 patients were staged II B and III with a mean survival time of 20 and 9 months respectively. Of the 16 patients treated, 10 (62.5%) continue survival with an overall median survival time of 25 months. It is suggested that an early diagnosis and combined treatment including surgery, radiotherapy and chemotherapy with vincristine, cyclophosphamide and actinomicin and possibly adriamycin as a fourth drug, will give patients in underdeveloped countries, similar survivals and relief as those observed in developed countries. It is apparent that a multidisciplinary medical team is more important than the magnitud of economical resources.

Antineoplastic Agents↗