Biomedical subjects

O Torres

Publications and source records attributed to O Torres.

At least 19 recordsLinked to original sources

PubMed2005

Total gastrectomy with or without abdominal drains. A prospective randomized trial.

The most common postoperative complications of total gastrectomy are esophagojejunal anastomotic leakage and subphrenic abscess. These complications are a cause of morbidity and mortality, relaparotomy, and longer postoperative stay. The use of abdominal drains is useful for the early diagnosis and management of anastomotic leaks. The aim of this study was to analyze our experience with total gastrectomy for gastric cancer in patients with and without abdominal drains, and to evaluate the results regarding postoperative morbidity, postoperative hospital stay, postoperative days for oral intake, relaparotomy and mortality. This prospective and randomized study examines the results in 60 consecutive patients (43 males and 17 females) with gastric cancer who underwent total gastrectomy in the Regional Clinical Hospital of Concepción, Chile, between 2000 and 2003. Patients were divided into two groups: group I (without drains) and group II (two drains). We found 31 patients in group I and 29 patients in group II. The mean length of postoperative stay was 12.9 days in group I and 18.8 days in group II (p = 0.0242, s.). Morbidity was 9.7% in group I and 37.9% in group II (p = 0.0242, s.). Re-explorations were more frequent in group II (24.1%) versus group I (9.7%) (p = 0.1239, n.s.). Postoperative days for oral intake were 9.4 in group I and 12.8 in group II (p = 0.0514, n.s.) Mortality was 0% in group I and 3.4% in group II (p = 0.4833, n.s.). In our experience, morbidity and postoperative hospital stay were statistically higher in the group of patients with abdominal drains.

Adult↗

PubMed2004

Analysis of the estrogen regulation of the zebrafish estrogen receptor (ER) reveals distinct effects of ERalpha, ERbeta1 and ERbeta2.

We have previously cloned and characterized three estrogen receptors (ER) in the zebrafish (zfERalpha, zfERbeta1 and zfERbeta2). We have also shown that they are functional in vitro and exhibit a distinct expression pattern, although partially overlapping, in the brain of zebrafish. In this paper, we have shown that the hepatic expression of these zfER genes responds differently to estradiol (E2). In fact, a 48-h direct exposure of zebrafish to E2 resulted in a strong stimulation of zfERalpha gene expression while zfERbeta1 gene expression was markedly reduced and zfERbeta2 remained virtually unchanged. To establish the potential implication of each zfER in the E2 upregulation of the zfERalpha gene, the promoter region of this gene was isolated and characterized. Transfection experiments with promoter-luciferase reporter constructs together with different zfER expression vectors were carried out in different cell contexts. The data showed that in vivo E2 upregulation of the zfERalpha gene requires ERalpha itself and a conserved transcription unit sequence including at least an imperfect estrogen-responsive element (ERE) and an AP-1/ERE half site at the proximal transcription initiation site. Interestingly, although in the presence of E2 zfERalpha was the most potent at inducing the expression of its own gene, the effect of E2 mediated by zfERbeta2 represented 50% of the zfERalpha activity. In contrast, zfERbeta1 was unable to upregulate the zfERalpha gene whereas this receptor form was able to tightly bind E2 and activate a reporter plasmid containing a consensus ERE. Altogether, these results indicated that the two ERbeta forms recently characterized in teleost fish could have partially distinct and not redundant functions.

Animals↗

PubMed2001

Systematic genetic study of Alzheimer disease in Latin America: mutation frequencies of the amyloid beta precursor protein and presenilin genes in Colombia.

Nearly all mutations in the presenilin 1 (PSEN1), presenilin 2 (PSEN2), and amyloid beta precursor protein (APP) genes lead to early-onset Alzheimer disease (EOAD, onset age at or before 65 years). In order to assess the genetic contribution of these genes in a series of Colombian AD cases, we performed a systematic mutation analysis in 11 autosomal dominant, 23 familial, and 42 sporadic AD patients (34% with age of onset < or = 65 years). No APP missense mutations were identified. In three autosomal dominant cases (27.2%), two different PSEN1 missense mutations were identified. Both PSEN1 mutations are missense mutations that occurred in early-onset autosomal AD cases: an I143T mutation in one case (onset age 30 years) and an E280A mutation in two other cases (onset ages 35 and 42 years). In addition, a novel PSEN1 V94M mutation was present in one early-onset AD case without known family history (onset age 53 years) and absent in 53 controls. The E318G polymorphism was present in five AD cases and absent in controls. In PSEN2, two different silent mutations were detected, including one not reported elsewhere (P129). The majority of the Colombian AD cases, predominantly late-onset, were negative for PSEN and APP mutations.

Age of Onset↗

PubMed2001

Effect of nitric oxide on megakaryocyte growth induced by thrombopoietin.

The present study investigated the effect of nitric oxide (NO) on megakaryocyte (Mk) proliferation induced by thrombopoietin (TPO). Low-density mononuclear cells (MNCs) and CD34+ cells from human bone marrow (BM) were cultured in liquid medium in the presence of sodium nitroprusside (SNP) or (Z)-1-[2-(aminoethyl)-N-(2-ammonioethyl) amino] diazen-1-ium-1, 2-diolate (DETA/NO) and then stimulated with TPO. Mk number decreased in both NO donors, as identified by flow cytometry 11 to 13 days after TPO stimulation. Nitrite, cyanide, or the carrier molecule DETA failed to reproduce the inhibition caused by NO donors. When CD34+ cells were treated with DETA/NO, the inhibition of Mk growth was even more pronounced than that in MNCs. Failure of the guanosine 3',5'-cyclic monophosphate (cGMP) analog 8-bromoguanosine 3',5'-cyclic monophosphate (8-Br-cGMP) to inhibit Mk proliferation suggests that cGMP is not involved in Mk suppression mediated by NO. On the other hand, DNA analysis by flow cytometry showed that apoptosis of CD34+ cells and Mks seemed to be at least one of the mechanisms associated with the cytotoxic DETA/NO effect. Stimulation of MNCs or CD34+ cells with tumor necrosis factor-alpha (TNF-alpha) and interferon-gamma (IFN-gamma) increased endogenous NO levels and suppressed Mk growth. Treatment with NO synthesis inhibitors such as L -N(G)-monomethyl arginine (L -NMMA) or L -N(G)-nitroarginine methyl ester hydrochloride (L -NAME) partially reversed Mk growth inhibition induced by TNF-alpha and IFN-gamma, although increased NO levels returned to normal values. The results presented here strongly indicate that NO regulates the growth of Mks induced by TPO by a direct effect on both progenitors and mature Mks.

Antigens, CD34↗

PubMed2001

Phase I clinical evaluation of a neutralizing monoclonal antibody against epidermal growth factor receptor in advanced brain tumor patients: preliminary study.

High levels of growth factors and their receptors have been demonstrated in human tumors. Gliomas and meningiomas are characterized by overexpression of epidermal growth factor receptor (EGF-R). Ior egf/r3, is a neutralizing murine monoclonal antibody (MAb) against EGF-R, and was generated at the Cuban Institute of Oncology. The antibody recognizes EGF-R with high affinity, inhibiting tyrosine kinase activation. A clinical trial was conducted in brain tumor patients to evaluate toxicity, immunogenicity, and clinical benefit of escalating doses of the antibody. Nine patients with histologically confirmed gliomas or meningiomas, who had active or recurrent disease after receiving conventional treatment, received four intravenous doses of ior egf/r3. Total dosages ranged from 160 to 480 mg. As inclusion criteria, radioimmunoscintigraphy with the same MAb labeled with 99mTechnetium (99mTc) was performed. Immune response against the murine antibody was also evaluated. After four doses of ior egf/r3 MAb, no significant toxicity was found, except in one patient who developed a grade 4 allergic adverse event. This reaction was probably related with previous sensitization to the same MAb and the development of human anti-mouse antibodies (HAMA) response. Despite no major objective antitumor responses, eight patients had stable disease on the 6-month evaluation, and two patients remain alive after four years of MAb therapy.

Adult↗

PubMed2001

Phase I clinical evaluation of a neutralizing monoclonal antibody against epidermal growth factor receptor.

Ior egf/r3, a neutralizing monoclonal antibody (mAb) against Epidermal Growth Factor Receptor (EGFR) was generated at the Cuban Institute of Oncology. Immunoscintigraphic studies in 148 patients with this 99-m Technetium (99Tc) labeled mAb, showed a high sensitivity and specificity for in vivo detection of epithelial tumors. To study safety, pharmacokinetic and immunogenicity of ior egf/r3 at high doses, a phase I clinical trial was conducted. Nineteen patients with advanced epithelial tumors received 4 mAb intravenous infusions at 6 dose levels: from 50 to 500 mg. Previously, immunoscintigraphic images using the same mAb labeled with 99Tc were acquired. Blood samples were collected for pharmacokinetic analysis and HAMA response. After mAb therapy, objective response was classified according to WHO criteria. Ior egf/r3 was well tolerated in spite of the high-administered doses. Only a severe adverse reaction consisting of hypotension and lethargy was observed. In 13 patients, selective accumulation of 99Tc-labeled mAb was observed at the site of the primary tumor or the metastasis. Pharmacokinetic analysis revealed that elimination half-life and the area under the time-concentration curve increased linearly with dose. HAMA response was detected in 17 patients. After 6 months of mAb therapy, 4 patients had stable disease. One patient had a tumor partial remission after 3 cycles of ior egf/r3.

Adult↗

PubMed2001

Association between plumage condition and fear and stress levels in five breeds of chickens.

Duration of tonic immobility and heterophil to lymphocyte ratio (indices of fear and stress, respectively) were compared in hens having very poor or perfect plumage at 72 wk of age. Five Spanish breeds of chickens (Castellana, Andaluza, Vasca, Villafranquina, and Leonesa) were used. There were significant differences among groups in terms of tonic immobility duration and heterophil to lymphocyte ratio (P < 0.05). Very poorly feathered hens showed shorter tonic immobility (243.03+/-26.81 s) and higher leukocyte ratio (0.42+/-0.02) than did hens with a perfect plumage (322.32+/-26.81 s and 0.35+/-0.02, respectively). Differences were consistent across the breeds. Thus, hens with very poor plumage were less fearful and more stressed than hens with a perfect plumage. The results suggest that very poor plumage is associated with indicators of fearfulness and stress.

Animal Welfare↗

PubMed2001

Cyclospora cayetanensis in three populations at risk in Guatemala.

In 1996 and 1997, outbreaks of Cyclospora cayetanensis in North America were linked to Guatemalan raspberries. From April 1999 to April 2000, we undertook a survey for C. cayetanensis in raspberry farm workers, malnourished children, and human immunodeficiency virus and AIDS patients in Guatemala. Stool samples were analyzed using ethylacetate-formalin concentration, wet preparation, modified acid-fast staining method, and epifluorescence. Oocysts were found in 1.5% of the subjects, none of whom were raspberry farm workers.

AIDS-Related Opportunistic Infections↗

PubMed2001

APOE epsilon4 and Alzheimer's disease: positive association in a Colombian clinical series and review of the Latin-American studies.

OBJECTIVE: As the strength of the association between the APOE epsilon4 allele and Alzheimer's disease (AD) varies across ethnic groups, we studied if there was such an association in Colombian patients. METHOD: We performed apolipoprotein E (APOE) genotyping in a clinical sample of 83 unrelated AD patients, predominantly late-onset (>65 yrs) including familial ( n =30) and sporadic AD cases (n= 53) diagnosed according to NINCDS-ADRDA criteria and assessed by a multi-disciplinary team. Control subjects (n = 44) had no significant cognitive impairment by medical interview and neuro-psychological testing. RESULTS: We found a high association (OR= 5.1 95%CI 1.9 -13.6) between APOE epsilon4 and AD, in this series with predominantly late-onset cases with familial aggregation in 24 cases (28.9%). A significant negative association was found between epsilon2 and AD (OR= 0.2 95% CI 0.05-0.75). CONCLUSION: Further population-based surveys in Colombia are warranted to precise a possible dose effect of APOE epsilon4.

Age of Onset↗

PubMed2000

Differences in genotypes of Helicobacter pylori from different human populations.

DNA motifs at several informative loci in more than 500 strains of Helicobacter pylori from five continents were studied by PCR and sequencing to gain insights into the evolution of this gastric pathogen. Five types of deletion, insertion, and substitution motifs were found at the right end of the H. pylori cag pathogenicity island. Of the three most common motifs, type I predominated in Spaniards, native Peruvians, and Guatemalan Ladinos (mixed Amerindian-European ancestry) and also in native Africans and U.S. residents; type II predominated among Japanese and Chinese; and type III predominated in Indians from Calcutta. Sequences in the cagA gene and in vacAm1 type alleles of the vacuolating cytotoxin gene (vacA) of strains from native Peruvians were also more like those from Spaniards than those from Asians. These indications of relatedness of Latin American and Spanish strains, despite the closer genetic relatedness of Amerindian and Asian people themselves, lead us to suggest that H. pylori may have been brought to the New World by European conquerors and colonists about 500 years ago. This thinking, in turn, suggests that H. pylori infection might have become widespread in people quite recently in human evolution.

Amino Acid Isomerases↗

PubMed1999

Nutritional status of Helicobacter pylori-infected children in Guatemala as compared with uninfected peers.

The effect of Helicobacter pylori infection on the nutritional status of children in a developing country was studied using a cross-sectional design. Children attending an all-girl public school in inner Guatemala City, Guatemala were evaluated to acquire sociodemographic information and anthropometric nutritional parameters (weight-for-height [WFH] and height-for-age [HFA]), and detect H. pylori-specific serum IgG antibodies. Of 211 children 5-10 years of age, 107 (51%) were infected. The WFH values were not different between infected and uninfected subjects, and were not affected by the sociodemographic variables. The HFA values decreased significantly with age (P = 0.008), lower income (P = 0.04), and H. pylori infection (P = 0.05). When controlled for age and income level, the effect of infection on HFA became nonsignificant (P = 0.30). Helicobacter pylori appeared to have no effect on the nutritional status of the studied children; the differences detected were small and likely due to sociodemographic factors.

Age Factors↗

PubMed1999

99mTc-labeled antihuman epidermal growth factor receptor antibody in patients with tumors of epithelial origin: Part III. Clinical trials safety and diagnostic efficacy.

UNLABELLED: Monoclonal antibody (moAb) ior egf/r3 is an IgG2a that recognizes the epidermal growth factor receptor (EGF-R). The aim of this study was to evaluate the diagnostic efficacy of the 99mTc-labeled moAb ior egf/r3 for the detection of epithelial-derived tumors, their metastases and recurrences. METHODS: One hundred forty-eight adult patients (51 women, 97 men; mean age 53 +/- 13 y) who were suspected of having cancer of epithelial origin were administered 3 mg/50 mCi (1.85 GBq) 99mTc-labeled moAb ior egf/r3 by intravenous bolus injection. Planar anterior and posterior images of the lesion sites and suspected metastases were acquired at 2, 4, 6 and 24 h after injection, and SPECT images were scanned at 5 h postinjection, using a 360 degrees circular orbit with 64 images. The backprojection method was used for image reconstruction with a Hamming-Hann filter. RESULTS: Labeling efficiency was always greater than 98.5% +/- 2.1 %. No adverse reactions or side effects were observed. Results of the biopsy specimens showed that 85.1% (126/148) of the patients had tumors of epithelial origin, 14.2% (21/148) were negative and 0.7% (1/148) had non-Hodgkin's lymphoma. The sensitivity rate by organ was as follows: brain (8/8, 100%), digestive tract (10/11, 90.9%), head and neck (17/23, 73.9%), lung (52/62, 83.9%) and breast (16/18, 88.9%). Overall sensitivity, specificity, accuracy, and positive and negative predictive values of the immunoscintigraphic imaging were 84.2% (106/126), 100.0% (22/22), 86.5% (128/148), 100% (106/106) and 52.4% (22/42), respectively. New metastases not identified previously by other diagnostic methods were detected in the 50% of the patients. CONCLUSION: Immunoscintigraphy with 99mTc-labeled moAb ior egf/r3 could be a useful procedure for the diagnosis and follow-up of the patients with tumors of epithelial origin.

Animals↗

PubMed1998

Effects of the water content in the sample preparation for MALDI on the mass spectra.

Ion abundances in the MALDI TOF mass spectra of the model peptides (bradykinin, alpha-melanocyte stimulating hormone, and melittin) change significantly as water is added to the solution used for dried droplet sample preparation. Changes in the surface tension of the solution can be invoked to explain some of the observed effects on the mass spectra. For example, at low surface tensions, the solution droplet spreads over a larger surface area, resulting in a dilution effect and thereby lowering the [M + H]+ ion yields. Analyte ion yields also have a dependence on matrix crystal morphology. The faster drying samples (low water percentage) promote better inclusion of the analyte into the matrix crystals as compared with the slower drying samples (high water percentage). More efficient inclusion of the analyte in the matrix crystal leads to a better matrix-analyte interaction and hence to higher [M + H]+ ion yields. We present new data that suggest that analyte conformation also influences the MALDI ion yields. The suggestion of conformation affecting MALDI ion yields is based on solvent composition dependence for MALDI H/D exchange data and circular dichroism spectra.

Bradykinin↗

PubMed1998

The safety and efficacy of Australian tick-borne disease vaccine strains in cattle in Paraguay.

Glycerol preserved, frozen tick-borne disease vaccine strains developed in Australia were imported into Paraguay to test their safety in pregnant Holando heifers and their efficacy against challenge from inoculated local field strains of Babesia bigemina, B. bovis and Anaplasma marginale in Hereford X Criolla heifers. The two Babesia strains proved to be safe and the B. bovis K strain was very effective in providing immunity to a local field strain of B. bovis. The B. bigemina efficacy trial was inconclusive, possibly due to the avirulent nature of the local field strain used in challenge. The A. centrale strain did not prove to be as safe as would be desirable in safety trials, neither did it provide as good protection as the Babesia strains in the efficacy trial. It was concluded that the Babesia strains provided good protection against field challenge in Paraguay and were safe to use in highly susceptible cattle, however an alternative to A. centrale should be sought to provide protection against local strains of A. marginale.

Anaplasma↗

PubMed1997

[Renal failure in patients with liver transplant: incidence and predisposing factors].

Renal failure is a common finding in patients undergoing orthotopic liver transplantation. The aim of the present study was to evaluate the incidence, prognostic value of pre, intra and postoperative factors and severity of renal dysfunction in patients who undergo liver transplantation. Therefore, the records of 38 consecutive adult patients were reviewed. Renal failure was defined arbitrarily as an increase in creatinine (> 1.5 mg/dl) and/or blood urea (> 80 mg/dl). Three patients were excluded of the final analysis (1 acute liver failure and 2 with a survival lower than 72 hs.) Twenty one of the 35 patients has renal failure after orthotopic liver transplantation. Six of these episodes developed early, having occurred within the first 6 days. Late renal impairment occurred in 15 patients within the hospitalization (40 +/- 10 days) (Mean +/- SD). In he overall series, liver function, evaluated by Child-Pugh classification, a higher blood-related requirements and cyclosporine levels were observed more in those who experienced renal failure than those who did not (p < 0.05). Early renal failure was related with preoperative (liver function) and intraoperative (blood requirements) factors and several causes (nephrotoxic drugs and graft failure) other than cyclosporine were present in patients who developed late renal impairment. No mortality. No mortality was associated with renal failure. We conclude that renal failure a) is a common finding after liver transplantation, b) the pathogenesis of this complication is multifactorial and, c) in not related with a poor outcome.

Adult↗

PubMed1995

Treatment of hypercholesterolemia in NIDDM with policosanol.

OBJECTIVE: To determine whether elevated levels of cholesterol and low-density lipoprotein (LDL) cholesterol in non-insulin-dependent diabetes mellitus (NIDDM) patients could be decreased by policosanol, a new cholesterol-lowering drug. NIDDM predisposes patients to coronary artery disease (CAD) through the direct action of hyperglycemia on the arteries as well as the dyslipidemia induced by NIDDM. RESEARCH DESIGN AND METHODS: This double-blind placebo-controlled trial was performed in 29 patients with NIDDM and hypercholesterolemia. After stable glycemic control was achieved by diet and/or oral hypoglycemic drugs, patients were instructed to follow a cholesterol-lowering diet for 6 weeks. Patients who met entry criteria received, under double-blind conditions, policosanol (5 mg) or placebo tablets twice a day for 12 weeks. RESULTS: Policosanol (10 mg/day) significantly reduced total cholesterol by 17.5% and LDL cholesterol by 21.8% compared with baseline and placebo. Furthermore, high-density lipoprotein (HDL) cholesterol was raised by 11.3% (not significant), and triglycerides showed a statistically nonsignificant decrease of 6.6%. These changes in lipid profile were similar to those induced by policosanol in nondiabetic patients with type II hyperlipoproteinemia. CONCLUSIONS: Glycemic control was unaffected by treatment. No clinically or biochemically adverse effects attributable to treatment were observed. Only one patient (placebo) withdrew from the trial because of an adverse experience (erythema). We concluded that policosanol is effective and safe in patients with NIDDM and hypercholesterolemia.

Anticholesteremic Agents↗

PubMed1995

CLECOS_P: clinical evolution control system on Parkinsonian patients undergoing neural transplantation.

The CLECOS_P system was conceived for registering and automating the processing of clinical evaluations performed on patients with Parkinson's disease who undergo functional neurosurgery and/or neural transplant. CLECOS_P represents the first time a computerized system is able to offer--with high precision and considerable time-savings--an integral analysis of the evolutive behavior of the universe in integrated variables at the core assessment program for intracerebral transplantations (CAPIT). CAPIT is used internationally for the evaluation and follow-up of patients with this pathology who have undergone neural transplant. We used the so-called MEDSAC methodology for the preparation of this system. The methodology that was used for the design of an intelligent system aimed at medical decision-making was based on the quantitative analysis of the clinical evolution. At the present moment, there are 20 patients controlled by this system: 11 bilaterally transplanted, 9 unilaterally (registered in ranks of 3 months before operation up to 1, 2, 3, 6, 9, 12, 18, and 24 months after operation). The application of CLECOS_P to these patients permitted the evaluation of 400 clinical variables, where a better evolutive characterization of the patients was obtained, thus getting most favorable results with personalized therapeutic methods aimed at raising their quality of life. CLECOS_P is used in a multi-user environment on a local area network running Novell Netware version 3.11.

Brain Tissue Transplantation↗

PubMed1993

Protection against Campylobacter diarrhea: role of milk IgA antibodies against bacterial surface antigens.

In developing countries, Campylobacter jejuni causes diarrhea and dysentery, especially in children less than one year of age. Breast feeding protects against infectious diarrhea, with milk IgA antibody playing a determining role. Therefore, it has been proposed to increase the protective effect of human milk by vaccinating women of child-bearing age. To identify antigens which may induce protective breast-milk IgA, we analyzed 60 strains of C. jejuni isolated from asymptomatically- and symptomatically-infected breast-fed children less than 12 months of age. Surface antigens of C. jejuni, separated by polyacrylamide gel electrophoresis, were probed with breast milk collected concurrently with the fecal sample from which C. jejuni was isolated, and specific IgA was developed by immunoblotting. Our results indicate that milk antibodies against three high molecular weight bacterial surface antigens of 95, 110 and 185 kDa are involved in protection of infants infected with C. jejuni (p = 0.00964 for one-tailed Fisher's exact test).

Antigens, Bacterial↗