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B Gomez

Publications and source records attributed to B Gomez.

At least 19 recordsLinked to original sources
PubMed2001

Determinants involved in Kv1 potassium channel folding in the endoplasmic reticulum, glycosylation in the Golgi, and cell surface expression.

Kv1.1 and Kv1.4 potassium channels are expressed as mature glycosylated proteins in brain, whereas they exhibited striking differences in degree of trans-Golgi glycosylation conversion and high cell surface expression when they were transiently expressed as homomers in cell lines. Kv1.4 exhibited a 70% trans-Golgi glycosylation conversion, whereas Kv1.1 showed none, and Kv1.4 exhibited a approximately 20-fold higher cell surface expression level as compared with Kv1.1. Chimeras between Kv1.4 and Kv1.1 and site-directed mutants were constructed to identify amino acid determinants that affected these processes. Truncating the cytoplasmic C terminus of Kv1.4 inhibited its trans-Golgi glycosylation and high cell surface expression (as shown by Li, D., Takimoto, K., and Levitan, E. S. (2000) J. Biol. Chem. 275, 11597-11602), whereas truncating this region on Kv1.1 did not affect either of these events, indicating that its C terminus is not a negative determinant for these processes. Exchanging the C terminus between these channels showed that there are other regions of the protein that exert a positive or negative effect on these processes. Chimeric constructs between Kv1.4 and Kv1.1 identified their outer pore regions as major positive and negative determinants, respectively, for both trans-Golgi glycosylation and cell surface expression. Site-directed mutagenesis identified a number of amino acids in the pore region that are involved in these processes. These data suggest that there are multiple positive and negative determinants on both Kv1.4 and Kv1.1 that affect channel folding, trans-Golgi glycosylation conversion, and cell surface expression.

Amino Acid Sequence↗
PubMed2001

Effects of low-dose alcohol exposure on simulated merchant ship piloting by maritime cadets.

The US Department of Transportation (DOT) regulates on-the-job alcohol use by operators of certain categories of commercial transport. For aircraft, trains, and commercial vessels, operators are subject to sanctions for having > or = 0.04 g% blood alcohol concentration (BAC). This study examines the effects of alcohol (between 0.04 and 0.05 g% BAC) on simulated merchant ship handling. A two-group randomized factorial design was used to compare beverage alcohol to placebo while controlling for baseline performance on a previous day. The study was conducted in the Maritime Simulation Center at Maine Maritime Academy, Castine, ME. Participants were 38 volunteer deck officer cadets in their junior or senior year, at least 21 years of age, with previous experience on a bridge simulator. Following a baseline trial on Day 1, on Day 2 participants were randomized to receive alcohol (0.6 g/kg for males and 0.5 g/kg for females) or placebo. After allowing time for absorption, participants completed a bridge simulator task. For baseline and performance trials, participants were randomized to one of four bridge simulator scenarios, each representing passage of a fully loaded container vessel through a channel with commercial traffic. The aggregate scenario score given by blinded maritime educators measured performance. A main effect for alcohol was found indicating that performance was significantly impaired by this low dose of alcohol relative to performance in the placebo condition. These findings are consistent with current federal regulations that limit low-dose alcohol exposure for the operators of commercial transport vehicles. Further research is required to determine effects at lower BACs.

Adult↗
PubMed2001

Persistence of respiratory syncytial virus in macrophages alters phagocytosis and pro-inflammatory cytokine production.

Functions of macrophage are known to be altered by acute infection with respiratory syncytial virus (RSV). However, it is unknown whether the persistent presence and expression of the RSV genome have any effect on the functions of these cells. We used a murine macrophage-like cell line (P388D1) persistently infected with RSV to determine: (i) phagocytic activity mediated by Fcgamma receptors, (ii) expression of Fcgamma receptors, and (iii) production of IL-1beta, IL-6 and TNF-alpha. Viral persistence was found to increase phagocytosis, expression of Fcgamma receptors and the production of IL-1beta and IL-6. In contrast the biological activity of secreted TNF-alpha decreased. In this study we give novel evidence that RSV persistence alters the biological activities of macrophages.

Animals↗
PubMed2000

A new species of Nehvizdya (Ginkgoales) from the Lower Cretaceous of the Iberian Ranges (Spain).

A new species of the formerly monospecific genus Nehvizdya Hlustík, Nehvizdya penalveri sp. nov. is described from the Albian of the Escucha Formation (Eastern Iberian Ranges, Teruel, Spain). The type species Nehvizdya obtusa Hlustík was first found in the Lower-Middle Cenomanian Peruc Member of the Peruc-Korycany Formation (Bohemian Massif, Czech Republic). Both taxa closely resemble each other, not only in leaf shape and venation pattern, but also in their epidermal structures and the occurrence of resin bodies. The Spanish species, however, is notable for its marked amphistomatic leaves with stomatal apparatus, which have inner folds inside the stomatal pits. Comparison with Eretmophyllum andegavense Pons et al. from the Cenomanian of the Baugeois Clays (Maine-et-Loire, France) allows us to transfer this species to the genus Nehvizdya Hlustík. The new combination proposed is Nehvizdya andegavense (Pons et al.) comb. nov. A taphonomic analysis in this layer appears to characterise a biocoenosis formed from N. penalveri sp. nov. and Frenelopsis alata (K. Feistmantel) Knoblock. Similar associations have been described in the Czech and French Cenomanian. In all three cases, the associations grew around coastal lagoons and ponds where they formed a shrubby halophyte vegetation.

Journal Article↗
PubMed1999

Phospholipase digestion of bound cardiolipin reversibly inactivates bovine cytochrome bc1.

Phospholipids and tightly bound cardiolipin (CL) can be removed from Tween 20 solubilized bovine cytochrome bc(1) (EC 1.10.2.2) by digestion with Crotalus atrox phospholipase A(2). The resulting CL-free enzyme exhibits all the spectral properties of native cytochrome bc(1), but is completely inactive. Full electron transfer activity is restored by exogenous cardiolipin added in the presence of dioleoylphosphatidylcholine (DOPC) and dioleoylphosphatidylethanolamine (DOPE), but not by cardiolipin alone or by mixtures of phospholipids lacking cardiolipin. Acidic, nonmitochondrial phospholipids, e.g., monolysocardiolipin or phosphatidylglycerol, partially reactivate CL-free cytochrome bc(1) if they are added together with DOPC and DOPE. Phospholipid removal from the Tween 20 solubilized enzyme, including the tightly bound cardiolipin, does not perturb the environment of either cytochrome b(562) or b(566), nor does it cause the autoreduction of cytochrome c(1). Cardiolipin-free cytochrome bc(1) also binds antimycin and myxothiazol normally with the expected red shifts in b(562) and b(566), respectively. However, the CL-free enzyme is much less stable than the lipid-rich preparation, i.e., (1) many chromatographic methods perturb both cytochrome b(566)() (manifested by a hypsochromic effect, i.e., blue shift of 1.5-1.7 nm) and cytochrome c(1) (evidenced by autoreduction in the absence of reducing agents); (2) affinity chromatographic purification of the enzyme causes pronounced loss of subunits VII and XI (65-80% decrease) and less significant loss of subunits I, IV, V, and X (20-30% decrease); and (3) high detergent-to-protein ratios result in disassembly of the complex. We conclude that the major role of the phospholipids surrounding cytochrome bc(1), especially cardiolipin, is to stabilize the quaternary structure. In addition, bound cardiolipin has an additional functional role in that it is essential for enzyme activity.

Animals↗
PubMed1999

Quantitative determination of cardiolipin in mitochondrial electron transferring complexes by silicic acid high-performance liquid chromatography.

Quantitative determination of cardiolipin from two mitochondrial electron-transferring complexes was achieved using a rapid and sensitive silicic acid HPLC method combined with digital analysis of the elution profile. Phospholipid samples containing as little as 0. 01 nmol of cardiolipin were accurately analyzed. Phospholipids from detergent-solubilized cytochrome bc1 (EC 1.10.2.2) and cytochrome c oxidase (EC 1.9.3.1) were extracted by an organic two-phase system and analyzed by isocratic normal-phase HPLC after dissolving the dried sample in the mobile phase (cyclohexane:2-propanol:5 mM phosphoric acid, 50:50:2.9, v/v/v). Analysis was performed by the method of standard addition in which increasing amounts of cardiolipin (0 to 5 nmol) are added to a constant amount of phospholipid extract containing an unknown amount of cardiolipin. By determining the slope and intercept of a plot of the HPLC elution peak area as a function of the amount of standard cardiolipin added, the amount of cardiolipin in the unknown is determined. By this analysis, purified, detergent-solubilized bovine heart cytochrome bc1 and cytochrome c oxidase contained 9.2 +/- 0.7 and 3.05 +/- 0.05 mol cardiolipin per mole of enzyme, respectively. The method was also used to prove that cardiolipin could be completely removed from each complex by digestion with Crotalus atrox phospholipase A2, i.e., each delipidated complex contained less than 0.05 mol cardiolipin per mole of complex. The rapidity and high sensitivity of this method make it very useful for analysis of cardiolipin in other biological samples.

Animals↗
PubMed1999

Immunopathogenesis of human gastrointestinal infection by Anisakis simplex.

BACKGROUND: Anisakis simplex is a parasite of fish, and in the case of human infestation, it should be considered as a possible cause of gastrointestinal disease, especially in countries where raw or undercooked fish is a frequent food. Clinical features of anisakiasis may simulate acute abdominal pain, such as that found in patients with gastric ulcers, appendicitis, and Crohn's disease. Furthermore, many cases of anisakiasis are diagnosed as eosinophilic gastroenteritis, which is a broad term for a specific disease. OBJECTIVE: The purpose of this study was to investigate the immunopathogenesis of human gastrointestinal infestation by A simplex. METHODS: Thirteen intestinal biopsy specimens from patients with anisakiasis were analyzed for the presence of messenger (m)RNA for different cytokines and inflammatory mediators by RT-PCR. Specific IgE, eosinophil cationic protein, eosinophil protein X, and tryptase levels were measured in each patient's serum. Also, cell cultures were set up with lymphocytes from some patients and stimulated in vitro with Anisakis and Ascaris antigens. RESULTS: We performed immunologic phenotyping in 13 patients. All patients underwent biopsy after emergency surgery caused by episodes of acute abdominal pain. In all cases inflammatory infiltrate composed of eosinophils and lymphocytes was found in the intestinal wall. We demonstrated that after infestation, a T(H2)-type immune response occurred. Also, major basic protein, nitric oxide, and eotaxin were found in the tissue, and eosinophil cationic protein and eosinophil protein X levels were elevated in sera. CONCLUSION: These data and in vitro lymphocyte cultures indicate that a T(H2) mechanism plays an important role in the inflammatory infiltrate produced by the anchorage of parasites in the gastrointestinal wall.

Abdominal Pain↗
PubMed1998

The re-emergence of American visceral leishmaniasis in an old focus in Venezuela: present situation of human and canine infections.

The report of a new autochthonous case of human American Visceral Leishmaniasis (AVL) in 1992 in the village of Guayabita, Aragua State, Venezuela (10 degrees 16'N, 67 degrees 28'W; 500 m asl), led us to undertake an epidemiological study in this locality. A demographic survey was conducted using a structured questionnaire in which data was collected regarding sex, age, occupation, length of residence in the area and migratory history. A leishmanin skin test (LST) was applied and samples of venous blood for counter immunoelectrophoresis (CIEP) and immunofluorescent antibodies (IFAT) tests were drawn. The prevalence of positive LST was 11.4%. The positivity was highest among males and increased with age. Young males seemed to be more exposed to infection than females. Since occupation per se did not seem to account for this association, it may be explained as a gender-associated behavior, leading to different degrees of exposure to sand flies. The canine population was also screened for leishmanial infection. One dog was shown to be parasitologically infected with Leishmania sp. Four out of 71 dogs (5.6%) were positive for FG, CIEP, IFAT and Western Blot and 11 (15.5%) were positive for CIEP. These results suggest that after almost 30 years of epidemiological silence, American visceral leishmaniasis has re-emerged in this focus.

Adolescent↗
PubMed1998

Measuring condom use among sex workers in the Dominican Republic.

The purpose of this paper is to assess the internal consistency of self-reported condom use among sex workers in Puerto Plata and Santo Domingo, Dominican Republic. We examined the responses to questions about condom use among 4 cross-sectional samples of sex workers. We compared measures based on: (1) questions using always-to-never scales; (2) questions about use with the past 5 clients; and (3) questions about use in the past week obtained from a retrospective coital log. In each sample, more women reported 'always' using condoms with clients than with each of the past 5 clients. In 3 of the 4 samples, only about half of the women who reported 'always' using condoms used condoms with the most recent 5 clients and with all clients in the past week. Internal consistency was significantly higher when the comparison was limited to use with the most recent 5 clients and use in the past week. Self-reported measures of condom use can be difficult to interpret. Assessing the internal consistency of several measures of use provides insight into the strengths and weaknesses of each measure.

Condoms↗
PubMed1998

Man-vector contact of phlebotomine sand flies (Diptera: Psychodidae) in north-central Venezuela as assessed by blood meal identification using dot-ELISA.

Human bait is traditionally used to assess man-vector contact, which is a key point in the study of the epidemiology of vector-borne diseases. However, in highly endemic foci, where this method should be avoided, this information could be obtained by blood meal analysis of engorged insects. In the village El Ingenio, Miranda State, Venezuela, Lutzomyia ovallesi and Lutzomyia gomezi are vectors of cutaneous leishmaniasis (CL). From June 1994 to March 1995, sand flies were collected inside houses on 974 CDC trap nights from 1900 to 0700 h. A total of 7,281 female sand flies were caught: 68.7% of them were identified as L. ovallesi, and 3.3% were identified as L. gomezi. Almost all of the blood-engorged flies (233 of 237) were dissected and identified, and gut contents were examined by dot enzyme-linked immunosorbant assay (dot-ELISA) using antisera against humans and common household animals including the domestic mouse. The Human Blood Index was 0.817 for L. ovallesi. These results suggest that intradomiciliary transmission may occur and account for the cases of CL frequently observed in newborn children in El Ingenio.

Animals↗
PubMed1997

Role of nitric oxide in the effects of hypoglycemia on the cerebral circulation in awake goats.

This study was performed to examine the role of nitric oxide in the effects of hypoglycemia on the cerebral circulation. Hypoglycemia was induced with insulin and its effects on cerebral blood flow (measured with an electromagnetic flow transducer placed on the internal maxillary artery) were studied in awake goats under control conditions and after administration of the nitric oxide synthesis inhibitor N(G)-nitro-L-arginine methyl ester (L-NAME, 47 mg/kg). Also, cerebrovascular reactivity to vasodilator stimuli was examined during insulin-induced severe hypoglycemia, before and after L-NAME treatment. In five animals under control conditions (glycemia = 90 +/- 7 mg/dl, cerebral blood flow = 64 +/- 4 ml/min, mean systemic arterial pressure = 102 +/- 4 mmHg, cerebrovascular resistance = 1.62 +/- 0.11 mmHg/ml per min and heart rate = 73 +/- 6 beats/min), insulin decreased glycemia: when hypoglycemia was moderate (glycemia = 46 +/- 2 mg/dl) or severe (glycemia = 26 +/- 1 mg/dl) cerebral blood flow increased by 25 +/- 4% and 47 +/- 6%, and cerebrovascular resistance decreased by 18 +/- 3% and 34 +/- 4%, respectively. Under basal conditions, L-NAME did not affect glycemia but reduced resting cerebral blood flow by 37 +/- 2%, increased mean arterial pressure by 33 +/- 2% and decreased heart rate by 28 +/- 3%; after L-NAME, both moderate and severe hypoglycemia did not alter significantly resting cerebral blood flow and cerebrovascular resistance. In five other goats, L-NAME, administered during severe hypoglycemia, abolished the increase in cerebral blood flow, and increased cerebrovascular resistance and mean arterial pressure over the control (normoglycemic) values. In these animals with severe hypoglycemia, acetylcholine (0.01-1 microg), isoproterenol (0.03-3 microg) and diazoxide (0.3-9 mg), injected into the internal maxillary artery, decreased cerebrovascular resistance in a dose-dependent manner, and this decrease was similar before and after L-NAME. Therefore, insulin-induced hypoglycemia may produce cerebral vasodilatation by releasing nitric oxide and may diminish the capacity of the cerebral vasculature to release nitric oxide in response to acetylcholine.

Acetylcholine↗
PubMed1997

Immunological markers of disease progression in patients infected with the human immunodeficiency virus.

Identification of inexpensive and technically simple immunological tests useful in predicting the progression to AIDS in human immunodeficiency virus (HIV)-infected patients would be especially welcome in developing countries, in which 80% of HIV-infected patients reside and health budgets are low. In the current study, we evaluated CD4+ and total lymphocyte counts and the concentrations in serum of beta 2-microglobulin, p24 antigen, and immunoglobulin A (IgA) as predictors of disease progression in 74 Panamanian HIV-positive patients and 50 HIV-negative healthy individuals. Total lymphocyte and CD4(+)-cell counts for AIDS patients (1,451 +/- 811 cells/microliters, P < 0.001, and 238 +/- 392 cells/microliters, P < 0.0001, respectively and asymptomatic patients (2,393 +/- 664 cells/microliters, P > 0.05, and 784 +/- 475 cells/microliters, P < 0.001, respectively) were lower than those observed for healthy subjects (2,596 +/- 631 cells/microliters and 1,120 +/- 296 cells/microliters, respectively). The levels of beta 2-microglobulin and IgA in serum were significantly elevated in patients with AIDS (5.7 +/- 3.6mg/liter, P < 0.001, and 541 +/- 265 mg/dl, P < 0.0002, respectively) and asymptomatic infected subjects (3.4 +/- 2.1 mg/liter, P = 0.001, and 436 +/- 216 mg/dl, P < 0.0001, respectively) compared with the levels in healthy subjects (2.2 +/- 0.7 mg/liter and 204 +/- 113 mg/dl, respectively). Nonstatistically significant differences (P > 0.05) for concentrations of p24 antigen between asymptomatic infected patients (29 +/- 13 pg/ml) and AIDS patients (40 +/- 23 pg/ml) were observed. Total lymphocyte counts of 1,750 cells/microliters or less, CD4 counts of 200 cells/microliters or less, beta 2-microglobulin concentrations in serum of 4 mg/liter or higher, concentrations of IgA in serum of 450 mg/dl or higher, and the presence in serum of p24 antigen were correlated with elevated risks for developing AIDS. Monitoring both total lymphocytes and beta 2-microglobulin identified 91% of the AIDS patients; these assays may allow reductions in the annual number of CD4(+)-cell evaluations and the costs associated with monitoring both total lymphocytes and beta 2-microglobulin identified 91% of the AIDS patients; these assays may allow reductions in the annual number of CD4(+)-cell evaluations and the costs associated with monitoring the immune status of HIV-positive patients.

Acquired Immunodeficiency Syndrome↗
PubMed1997

[Aplastic anemia. Alternative treatment by bone marrow transplantation].

We report a case of a 25-year-old woman, with the diagnosis of severe aplastic anemia without a histocompatible sibling donor for bone marrow transplantation. The patient has been treated successfully with a combination of two immunosuppressive agents, cyclosporine and antilymphocyte globulin, after not responding to primary therapy with corticosteroids and growth factors. She showed a complete response to treatment, with transfusional independence, after a follow-up of 14 months. The pathophysiology of aplastic anemia, the mechanism of action and secondary effects of these treatments are discussed.

Adult↗
PubMed1996

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Centers for Medicare and Medicaid Services, U.S.↗