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Biomedical subjects

G Rojas

Publications and source records attributed to G Rojas.

At least 55 records · Page 3Linked to original sources
PubMed1996

[Antineutrophil cytoplasmic antibodies and nonspecific ulcerative colitis].

We studied the presence of antineutrophil cytoplasmic antibodies in 16 patients with idiopathic ulcerative colitis, using an indirect immunofluorescence technique and specific ELISA for myeloperoxidase and proteinase 3. Twelve patients had an active disease and in ten, antineutrophil cytoplasmic antibodies were positive, with a predominantly perinuclear distribution and without specificity for myeliperoxidase or proteinase 3. These antibodies were negative in the four patients with inactive disease. It is concluded that antineutrophil cytoplasmic antibodies could be serologic indicators of disease activity in patients with ulcerative colitis.

Adult↗
PubMed1995

A sandwich ELISA based on anti-apo(a) and anti-apo B monoclonal antibodies for lipoprotein(a) measurement.

Lipoprotein(a) (Lp(a)) is one of the most important independent risk factors for the prediction of premature atherosclerosis. Lp(a) is a low-density lipoprotein (LDL)-like particle which contains a glycoprotein (apoprotein(a)) disulfide linked to apo B-100. We describe a sandwich ELISA based on an anti-apo(a) monoclonal antibody (MAb) and an anti-apo B MAb for the quantitative determination of Lp(a) in human serum. The assay is sensitive, precise and specific. Samples with different apo(a) isoforms had a linear response in a range of 3-70 mg/dl of Lp(a). Correlations between the ELISA and a commercial ELISA, an immunoradiometric assay and electroimmunodiffusion were 0.92, 0.96 and 0.98, respectively. The frequency distribution of Lp(a) concentration in blood donors showed the skew toward the right reported in other populations. Patients with angiographically assessed coronary atherosclerosis had three times higher levels of Lp(a) than those with no signs of coronary atherosclerosis.

Animals↗
PubMed1995

(Evaluation of neutralizing ability of four commercially available antivenoms against the venom of Bothrops asper from Costa Rica)

We studied the ability of four commercially available antivenoms to neutralize several toxic and enzymatic activities of Bothrops asper (terciopelo) venom from Costa Rica. Experiments with preincubation of venom and antivenom were carried out to test the neutralization of lethal, hemorrhagic, coagulant and indirect hemolytic activities. In addition, antibody titers against crude venom and myotoxin II purified from this venom were determined by enzyme immunoassay (ELISA). Results indicate that polyvalent antivenom from Instituto Clodomiro Picado (Costa Rica) has the highest neutralizing ability against lethal, coagulant and indirect hemolytic activities, whereas MYN polyvalent antivenom (México) has the highest neutralization against hemorrhagic activity. Antivenom from Instituto Clodomiro Picado also has the highest antibody titers against crude B. asper venom and against myotoxin II. Antivenoms from Universidad Central de Venezuela (Venezuela), Vencofarma (Brazil) and MYN (México) failed to neutralize the lethal effect of this venom. These results stress the need for rigorous quality control systems to evaluate the neutralizing ability of antivenoms in Central America.

Animals↗
PubMed1995

Angiographic evaluation after portal blood flow preserving operations.

We carried out a prospective study comparing postoperative portal angiographic characteristics in patients with hemorrhagic portal hypertension treated electively by two different portal blood flow preserving procedures. Between 1986 and 1991, a total of 81 patients underwent operation: 38 selective shunts and 43 Sugiura-Futagawa procedures. Cirrhosis was shown by biopsy in 50 cases, 26 of them secondary to alcoholism. We found rebleeding in 5% of the patients, incapacitating postoperative encephalopathy in 8%, and an operative mortality of 7%. Fifty-two cases were evaluated in the postoperative period with angiography; 21 patients treated with a Sugiura-Futagawa operation were excluded due to portal vein thrombosis shown in the preoperative studies. Postoperative portal vein thrombosis was found in 11 cases (21%) [seven cases in the Warren group (21%) and four cases in the Sugiura-Futagawa group (20%)]. Decreased portal vein diameter was seen in eight cases (15%). The two procedures maintained hepatopedal portal blood flow, and no change was seen in relation to the preoperative state in 66% of the operated patients. We found no significant differences between the two procedures. Selection of procedure depends on the individual characteristics of each patient.

Adult↗
PubMed1994

Immune response impairment, genotoxicity and morphological transformation induced by Taenia solium metacestode.

In chronic helminthic infections such as cysticercosis, where the parasites live for years, profound modulation of the host immune response has been reported. To evaluate the genotoxicity of a drug used to treat cysticercosis, we observed the occurrence of genetic damage in cultured lymphocytes from cysticercotic swine and patients who had not been exposed to the drug. The human lymphocytes also showed a slower proliferation. These data suggested that the disease itself was promoting genetic damage in host lymphocytes which, in part, could explain the retardation of the lymphocyte proliferation observed in cysticercotic patients. Pigs infected with Taenia solium cysticerci showed an increased lymphocyte proliferation for 6-8 weeks post infection, followed by an impaired proliferation after this period. Significant induction of sister-chromatid exchanges was also observed in lymphocytes from infected pigs after the 6th week post infection. Additionally, it was found that a factor secreted by the cysticerci morphologically transformed primary fibroblasts in culture. The results strongly suggest that the parasite produces genetic instability in the host cells, which could result in immunosuppression and malignant transformation of target cells.

Animals↗
PubMed1994

Caprylic acid fractionation of hyperimmune horse plasma: description of a simple procedure for antivenom production.

A simple methodology for hyperimmune horse plasma fractionation, based on caprylic acid precipitation, is described. Optimal conditions for fractionation were studied; the method gives best results when concentrated caprylic acid was added to plasma, whose pH had been adjusted to 5.8, until a final caprylic acid concentration of 5% was reached. The mixture was vigorously stirred during caprylic acid addition and then for 60 min; afterwards the mixture was filtered. Non-immunoglobulin proteins precipitated in these conditions, whereas a highly enriched immunoglobulin preparation was obtained in the filtrate, which was then dialysed to remove caprylic acid before the addition of NaCl and phenol. Thus, antivenom was produced after a single precipitation step followed by dialysis. In order to compare this methodology with that based on ammonium sulfate fractionation, a sample of hyperimmune plasma was divided into two aliquots which were fractionated in parallel by both methods. It was found that caprylic acid-fractionated antivenom was superior in terms of yield, production time, albumin/globulin ratio, turbidity, protein aggregates, electrophoretic pattern and neutralizing potency against several activities of Bothrops asper venom. Owing to its efficacy and simplicity, this method could be of great value in antivenom and antitoxin production laboratories.

Ammonium Sulfate↗
PubMed1994

Survival and quality of life after portal blood flow preserving procedures in patients with portal hypertension and liver cirrhosis.

Between 1979 and 1991, 156 patients with histologically proven liver cirrhosis, good liver function, and bleeding portal hypertension underwent operation with portal blood flow preserving procedures (selective shunts: 101; Sugiura-Futagawa: 55). Long-term results of the procedures and the quality of life of the 145 patients who survived the operation were studied. During the observation period (range 3 to 156 months), 28 patients died. The main causes of death were liver failure and hepatoma. Twenty-three patients were lost for follow-up. Twenty-six patients (18%) developed 1 or more encephalopathic episodes. Four patients (3%) experienced rebleeding. One hundred eight patients (74%) had a good quality of life, and 26 (18%) had a poor quality of life. Eleven (15%) of 73 patients with a history of alcoholism continued drinking. Five-year survival for the selective shunt group was 81% and for the devascularization group was 83%. In 81% of the patients, portal blood flow was maintained. It is concluded that both procedures are effective in the long-term. Most patients are able to rehabilitate from the use of alcohol, and most of them have a good quality of life. For patients with good liver function (whose main problem is bleeding), surgery is the best choice of treatment.

Adult↗
PubMed1993

Turbidity of hyperimmune equine antivenom: the role of phenol and serum lipoproteins.

Twenty batches of polyvalent antivenom produced at the Instituto Clodomiro Picado were analyzed for turbidity, both before and after freezing-thawing and lyophilization. Eight batches became turbid upon freezing-thawing, and this change correlated with high levels of cholesterol, triglycerides and lipoproteins, especially beta-lipoprotein. Since normal horse serum does not become turbid after freezing-thawing, despite the fact that it has high lipoprotein levels, the possibility was raised that phenol, used as a preservative during serum fractionation, might affect lipoproteins, inducing the appearance of turbidity after freezing-thawing. This hypothesis was tested by fractionating a sample of hyperimmune serum either without phenol or using two different phenol concentrations (0.1 g/dl and 0.25 g/dl). Results showed that, although the three samples had the same cholesterol and triglyceride levels before fractionation, only the one having 0.25 g/dl phenol became turbid upon freezing-thawing, containing a diffuse lipoprotein band on electrophoresis. This finding suggests that turbidity in equine antivenoms depends on the interaction of at least three factors: (a) freezing, (b) high initial cholesterol and lipoprotein concentration in the serum, and (c) addition of phenol during fractionation of serum.

Animals↗
PubMed1993

Selective splenocaval shunt for bleeding portal hypertension: fifteen-year evaluation period.

BACKGROUND: Splenocaval shunts have been used in this hospital since 1974 as an alternative to the distal splenorenal shunt. This report will detail the long-term results with this operation. METHODS: Thirty-three patients who were subjected to selective splenocaval shunts for treatment of hemorrhagic portal hypertension are reported. Mean age was 48.4 years. Twenty patients were women. Twenty-seven patients were in Child class A and six were in Child class B. RESULTS: There were five postoperative deaths. Two patients experienced rebleeding. One patient had shunt obstruction and one patient had severe clinical encephalopathy. Actuarial survival rate was 54.9% at 5 years and was 47.5% at 15 years. At the time of evaluation 12 patients were alive and well (shortest observation period, 2 months and longest observation period, 173 months). One of these patients has mild encephalopathy. CONCLUSIONS: Selective splenocaval shunts are a good alternative for treatment of hemorrhagic portal hypertension in patients with good liver function.

Actuarial Analysis↗
PubMed1992

Experimental myonecrosis induced by the venoms of South American Micrurus (coral snakes).

Venoms from 11 taxa of Micrurus (coral snakes) from Brazil and Colombia were tested for myotoxic activity in mice. All venoms, except that of M. surinamensis, induced myotoxicity as judged by the increase in plasma creatine kinase levels and by histological analysis. Qualitatively, these venoms induced a similar necrotic pattern, although there were conspicuous quantitative differences between them.

Animals↗
PubMed1992

[Laparoscopic cholecystectomy in pediatrics. A report of the first case in the Mexican literature].

The authors present the case of a 9.8-year-old girl with 5 a month history of epigastric pain which was due to gallstones as demonstrated by ultrasound. After an extensive work-up failed to reveal associated hematologic problems, she was successfully treated by laparoscopic cholecystectomy, resulting in complete recovery, hospitalization of 22 hours and return to school three days after major surgery. We could not find references of laparoscopic cholecystectomy in the pediatric age group in the Mexican literature and only 3 in English language publications. In cases of cholelithiasis without associated diseases in children, the operation of choice should be laparoscopic cholecystectomy.

Child↗