PubMed Health⌕ Search

Biomedical subjects

J Torres

Publications and source records attributed to J Torres.

At least 37 records · Page 2Linked to original sources

Mapping the energy surface of transmembrane helix-helix interactions.

Transmembrane helices are no longer believed to be just hydrophobic segments that exist solely to anchor proteins to a lipid bilayer, but rather they appear to have the capacity to specify function and structure. Specific interactions take place between hydrophobic segments within the lipid bilayer whereby subtle mutations that normally would be considered innocuous can result in dramatic structural differences. That such specificity takes place within the lipid bilayer implies that it may be possible to identify the most favorable interaction surface of transmembrane alpha-helices based on computational methods alone, as shown in this study. Herein, an attempt is made to map the energy surface of several transmembrane helix-helix interactions for several homo-oligomerizing proteins, where experimental data regarding their structure exist (glycophorin A, phospholamban, Influenza virus A M2, Influenza virus C CM2, and HIV vpu). It is shown that due to symmetry constraints in homo-oligomers the computational problem can be simplified. The results obtained are mostly consistent with known structural data and may additionally provide a view of possible alternate and intermediate configurations.

Calcium-Binding Proteins↗

Traumatic intrapericardial diaphragmatic hernia: case report and literature review.

A traumatic rupture of the diaphragm, with herniation of the abdominal viscera into the thoracic cavity, is relatively rare, being observed in approximately 3-7% of all abdominal or thoracic traumas [1]. Herniation into the pericardium is very rare [2]. We have reviewed the post-traumatic intrapericardial diaphragmatic hernias (TIPDH) published in the world literature within our reach and, as it was already stated in the review carried out by Van Loenhout et al. [3] in 1986, approximately one post-traumatic intrapericardial hernia is reported every year. The patient that we present makes case 82 of those published until October of 1999.

Accidents, Traffic↗

Heterogeneous lack of expression of the tumour suppressor PTEN protein in human neoplastic tissues.

PTEN, a tumour suppressor gene located at chromosome 10q23 and commonly mutated or deleted in a variety of tumours, encodes a dual-specific/phosphatidylinositol-3,4,5-triphosphate (PIP3) phosphatase. We report the generation of an anti-PTEN monoclonal antibody (MAb) that recognises an epitope at the C-terminus of PTEN, and describe the heterogeneous lack of expression of the PTEN protein in human tumour tissues, as demonstrated by immunohistochemical methods. Our anti-PTEN MAb provides a useful tool for the study of PTEN protein expression in tumour samples, in the search for tumour prognostic molecular markers.

Animals↗

Determination of physical properties of bitumens by use of near-infrared spectroscopy with neural networks. Joint modelling of linear and non-linear parameters.

The fact that bitumens behave as non-Newtonian fluids results in non-linear relationships between their near-infrared (NIR) spectra and the physico-chemical properties that define their consistency (viz. penetration and viscosity). Determining such properties using linear calibration techniques [e.g. partial least-squares regression (PLSR)] entails the previous transformation of the original variables by use of non-linear functions and employing the transformed variables to construct the models. Other properties of bitumens such as density and composition exhibit linear relationships with their NIR spectra. Artificial neural networks (ANNs) enable modelling of systems with a non-linear property-spectrum relationship; also, they allow one to determine several properties of a sample with a single model, so they are effective alternatives to linear calibration methods. In this work, the ability of ANNs simultaneously to determine both linear and non-linear parameters for bitumens without the need previously to transform the original variables was assessed. Based on the results, ANNs allow the simultaneous determination of several linear and non-linear physical properties typical of bitumens.

Journal Article↗

Molecular detection of respiratory syncytial virus in postmortem lung tissue samples from Mexican children deceased with pneumonia.

BACKGROUND: Respiratory syncytial virus (RSV) is the major viral cause of severe respiratory infections in children younger than 2 years of age. Nevertheless there are not enough epidemiologic data about the role of RSV as a cause of infantile mortality from pneumonia, mainly in young children from developing countries Aim. To determine the frequency of RSV infection in lung tissue samples from Mexican children deceased with pneumonia, by reverse transcription (RT) and PCR. METHODS: Postmortem lung tissue samples from 98 children younger than 2 years of age who died of pneumonia during the period of 1989 to 1997 were studied. Paraffin was removed with xylene from 10-microm lung sections, the total RNA was extracted and complementary DNA was obtained by RT reaction. A nested PCR with the use of oligonucleotides specific for the F glycoprotein gene was developed. Samples negatives for RSV were tested for the absence of polymerase inhibitors and for complementary DNA integrity. RESULTS: Twenty-nine of the 98 (30%) children deceased with pneumonia were positive for RSV by RT-PCR; 8 were detected from 13 (62%) children with histopathologic diagnosis of viral pneumonia and 21 from 85 (25%) children with histopathologic diagnosis of bacterial pneumonia (P = 0.018). There was no significant difference in RSV infection according to age groups or seasonal pattern. CONCLUSIONS: RSV infection is frequent in Mexican children younger than 2 years of age who died of pneumonia. Although RSV was more common in viral pneumonia, mixed infections with RSV and bacterial pneumonia were also common.

Autopsy↗

Validation of the string test for the recovery of Helicobacter pylori from gastric secretions and correlation of its results with urea breath test results, serology, and gastric pH levels.

The efficacy of the string culture test to isolate Helicobacter pylori from gastric secretions of 28 volunteers was studied. With the urea breath test (UBT) as the "gold standard," the string culture test showed a sensitivity of 75% and a specificity of 100%. The results of string culture did not correlate with the UBT results, with serum antibody levels, or with the pH levels of gastric secretions.

Adult↗

Helminths in the wolf, Canis lupus, from north-western Spain.

Fifteen helminth species were collected from 47 wolves (Canis lupus ) which were surveyed from 1993 to 1999 in northwestern Spain. These included the trematode Alaria alata (2.1%); the cestodes Taenia hydatigena (44.7%), T. multiceps (29.8%), T. serialis (2.1%), Dipylidium caninum (6.4%) and Mesocestoides sp. aff. litteratus (4.2%); and the nematodes Pearsonema plica (7.4%), Trichuris vulpis (10.6%), Trichinella britovi (12.8%), Ancylostoma caninum (8.5%), Uncinaria stenocephala (51.1%), Toxocara canis (6.4%) Toxascaris leonina (4.2%), Angiostrongylus vasorum (2.1%) and Dirofilaria immitis (2.1%). Only two wolves were not infected. A single infection occurred in 28.9% of the cases, but the commonest infracommunity (31.1%) involved three species. The helminths Alaria alata, Taenia hydatigena, Mesocestoides sp. aff. litteratus, P. plica, Trichuris vulpis, and Ancylostoma caninum parasitizing C. lupus are reported for the first time in Spain. Taenia serialis and D. immitis are reported for the first time in wolves in Europe. Angiostrongylus vasorum represents a new host record for wolves. The helminth fauna of Spanish wolves is compared with that of other European wolf populations. Some epidemiological considerations of the helminth fauna of wolves in Spain and the health risk to humans are also discussed.

Animals↗

The occurrence of Cryptosporidium parvum and C. muris in wild rodents and insectivores in Spain.

Five rodent and two insectivore species were investigated for Cryptosporidium at seven sites in north-eastern Spain. Of the 442 animals studied, 82 Apodemus sylvaticus, 1 A. flavicollis, 5 Mus spretus, 1 Rattus rattus, 8 Clethrionomys glareolus and 13 Crocidura russula were infected with only C. parvum. Eleven A. sylvaticus and 2 C. glareolus were infected with only C. muris and 16 A. sylvaticus, 1 M. spretus and 2 C. glareolus showed mixed infections. Both cryptosporidial species were found in most study areas. No causal relationship was found between intrinsic host factors (age and sex) and the parasitic prevalence in the most captured host species (A. sylvaticus and C. russula). Extrinsic factors such as collection site of host, seasonality and covering vegetation exerted different influence on the prevalence of Cryptosporidium. Small mammals could become one of the most important sources of cryptosporidial oocysts in those areas where neither farm animals nor significant human activity are present. This is the first study to report the infection of M. spretus and C. russula by C. parvum and the first finding of C. muris in M. spretus.

Age Factors↗

Helicobacter pylori vacA and cagA genotypes in Mexican adults and children.

Studies examining associations between Helicobacter pylori virulence markers and disease have concentrated on adults in developed countries. This study assessed adults and children in Mexico. Ninety patients were recruited, 56 adults (37 with active peptic ulceration and 19 with no ulcers) and 34 children (all with recurrent abdominal pain and no ulcers). H. pylori was cultured from gastric biopsy specimens, and vacA alleles and cagA were typed by use of polymerase chain reaction from multiple colony sweeps. Multiple vacA types were common in single-biopsy isolates and were more frequent in adults with ulcers (95%) than in adults without ulcers (37%; P<.001) or in children (52%; P<.01). vacA s1b and cagA+ strains were more frequent in adults than in children. vacA s1 and cagA+ strains had similar frequencies in adults with and without ulcers. In conclusion, infection with multiple H. pylori strains, defined by different vacA genotypes, is common in Mexico. Such mixed infection is associated with ulcer disease. Strain populations infecting Mexican adults and children differ.

Adolescent↗

Use of a new label, (13)==(18)O, in the determination of a structural model of phospholamban in a lipid bilayer. Spatial restraints resolve the ambiguity arising from interpretations of mutagenesis data.

A structural model of pentameric phospholamban (Plb) in a lipid bilayer has been derived using a combination of experimental data, obtained from ATR-FTIR site-directed dichroism, and the implementation of the resulting restraints during a molecular dynamics simulation. Plb (residues 24-52) has been synthesised incorporating a new label, 1-(13)C==(18)O, at residues 42 and 43. We have not only determined the tilt of the helices, 10(+/-6) degrees, but also the relative orientation of the transmembrane segments, with an omega angle of -32(+/-10) degrees for L42. This angle is taken as zero in the direction of the helix tilt. Plb is a simple test case where site-directed dichroism has been applied to resolve the indeterminacy arising from the mutagenesis data available. The results presented point specifically to a single structural model for Plb.

Amides↗

Cytochrome c oxidase rapidly metabolises nitric oxide to nitrite.

Previous studies have shown that the addition of nitric oxide to cytochrome c oxidase rapidly generates spectral changes compatible with the formation of nitrite at the binuclear haem:copper centre. Here we directly demonstrate nitrite release following nitric oxide addition to the enzyme. The nitrite complex is kinetically inactive and the off rate for nitrite was found to be slow (0.024 min(-1)). However, the presence of reductants enhances the off rate and enables cytochrome oxidase to catalyse the rapid oxidation of nitric oxide to nitrite free in solution. This may play a major role in the mitochondrial metabolism of nitric oxide.

Electron Transport Complex IV↗

[Norwalk virus-like food poisoning after eating oysters].

BACKGROUND: The aim of this study was to conduct a clinical-epidemiological and microbiological investigation into an outbreak of food-borne disease due to the consumption of oysters. PATIENTS AND METHODS: A historic cohort study was conducted into the consumption of 15 food items and clinical symptoms. The influence of each foodstuff was assessed by Mantel-Haenzel stratified relative risk (RRM-H) at 95% confidence intervals, and was confirmed by dose-response analysis with a chi 2 test tendency. We investigated sample stools from 5 patients and 2 food-handlers. RESULTS: The overall attack rate was 38.0% (19/50). The median period of incubation was 39.0 h (maxim 62 and minimum 3 h). The symptoms were: fever 17.6% (3/17), diarrhoea 57.9% (11/19), vomits 84.2% (16/19), nausea 89.5% (17/19) and abdominal pain 89.5% (17/19). In stratified analysis, the Mantel-Haenzel method revealed a statistically risk for oysters (RRM-H = 3.3; IC 95%: 1.1-8.7), while the RRM-H value for sea snails was not significant (RRM-H = 2.8; IC 95%: 0.9-41.1). For oyster consumption, the dose-response test was statistically significant (p = 0.005). Examination by electron microscopy revealed small round structured viruses compatible with Norwalk-like virus. The oyster contamination was reported to the public health authority. CONCLUSIONS: This research highlights the usefulness of dose-response analysis in presenting epidemiological evidence, reveals the potential role of oyster consumption in food-borne disease such us Norwalk-like virus and show the need for monitoring production centres and oyster beds in order to prevent further cases of contamination.

Adult↗

Skin and wound infection by rapidly growing mycobacteria: an unexpected complication of liposuction and liposculpture. The Venezuelan Collaborative Infectious and Tropical Diseases Study Group.

OBJECTIVE: To describe 10 patients with skin and soft tissue infection caused by rapidly growing mycobacteria after cosmetic liposuction and liposculpture. DESIGN: Case series. SETTINGS: Eight private geographically separate surgical facilities from a single metropolitan area. PATIENTS: Eight patients with definite and 2 with presumptive cases of skin and soft tissue infection caused by rapidly growing mycobacteria after cosmetic surgery procedures during a 24-month period. Microorganisms were isolated from the purulent drainage obtained from wounds or fistulas in 8 cases and were identified as Mycobacterium fortuitum (3 cases) and Mycobacterium abscessus (5 cases) by routine microbiologic techniques. Acid-fast bacilli were observed on Ziehl-Neelsen-stained smears in the 2 remaining cases, but these ultimately failed to grow. In 2 of the surgical units, no apparent environmental predisposing factors were identified after thorough microbiologic environmental investigation. Clinically, all patients exhibited signs of inflammation, microabscesses, and purulent wound drainage within 24 months of abdominal and/or thigh liposuction or homologous fat tissue injection. INTERVENTION: A combined therapeutic approach including surgical drainage, debridment, and prolonged (>3 months) treatment with combined antimicrobial agents including clarithromycin was used in all cases. RESULTS: Nine of 10 patients responded to the combined therapeutic approach, and no evidence of infection was present during at least 12 months of follow-up. CONCLUSION: To our knowledge, this is the first series of patients with rapidly growing mycobacterial infections to be described after liposuction and liposculpture. Rapidly growing mycobacteria should be included in the differential diagnosis of skin and soft tissue infection after cosmetic surgery.

Abdomen↗

Ventriculopleural shunting with new technology valves.

Ventriculoperitoneal shunting constitutes the standard procedure for draining cerebrospinal fluid (CSF) in children with hydrocephalus. Ventriculoatrial and ventriculopleural shunting are alternative methods of CSF drainage, which have gained less acceptance. Ventriculopleural shunts are seldom used owing to justified fears of pneumothorax and symptomatic effusions of CSF. The addition of an antisiphon device to standard shunt systems seems to have prevented CSF pleural effusion. From 1988 to 1998, we treated each of six hydrocephalic children with a ventriculopleural shunt. In five cases we used new-technology valves designed to prevent the effects of siphoning with current differential pressure valves. Peritoneal adhesions, recent peritonitis, ascites, and obstruction of a previous ventriculoatrial shunt were the indications for pleural shunting. After a mean follow-up period of 2.5 years all shunts were functioning adequately. Only one patient showed transient symptoms of CSF overdrainage, which were corrected by up-grading the valve setting with the magnet. A late death was unrelated to the pleural shunting procedure. The use of valves of a new design designed to prevent overdrainage seems to account for the satisfactory outcomes observed in this series. We suggest that ventriculopleural shunting should be considered as the preferred alternative to peritoneal drainage in children with intra-abdominal adhesions or with a history of recent peritoneal infection.

Child↗

Further report on Cryptosporidium in Barcelona zoo mammals.

The prevalence of fecal shedding of Cryptosporidium in 36 primates (21 species and subspecies) and 62 herbivores (36 species and subspecies) housed at the Barcelona zoo was studied. Cryptosporidial oocysts were found in stool samples of 14 Primate, 18 Artiodactyla, 2 Perissodactyla, and 1 Proboscidea species. None of them showed symptoms related to the parasite. Neither the sex nor the group condition (alone or in a group) of the animals studied appeared to be correlated with parasitic prevalence. The results extend the host species range of the protozoan to 18 new animals (6 Primate, 10 Artiodactyla, 1 Perissodactyla, and 1 Proboscidea species) and confirm the endemic status of Cryptosporidium at the Barcelona zoo. We conclude that maintenance of the parasitic endemic status is probably due to the presence of animal carriers as well as to the physical features of some facilities where oocysts could remain viable and infectious.

Animals↗