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Biomedical subjects

I Sanchez

Publications and source records attributed to I Sanchez.

At least 19 recordsLinked to original sources
PubMed2001

Molecular epidemiology of HIV type 1 subtypes in equatorial guinea.

Equatorial Guinea is endemic for HIV-1. This country borders to the north with Cameroon, where different subtypes belonging to group M, as well as group O strains, are circulating simultaneously. To assess the molecular epidemiology of HIV-1 in Equatorial Guinea we analyzed 76 plasma samples collected throughout 1999 from seropositive individuals. Phylogenetic analysis of the gp41 region revealed that 53 were of subtype A, with 64% of these sequences clustering with CRF02_AG reference strains; 11 were of subtype C; 4 were of subtype D; 2 (closely related to subtype F2) were of subtype F; 3 were of subtype G, two of them forming a separate cluster with the recombinant circulating forms CRF06_cpx; 1 was of subtype H; and 2 were unclassifiable. Although subtype A is predominant, the presence of 14% of subtype C is also noteworthy. This work represents the first HIV-1 subtype distribution study in Equatorial Guinea.

Base Sequence↗
PubMed2000

Evaluation of DNA damage in exfoliated tear duct epithelial cells from individuals exposed to air pollution assessed by single cell gel electrophoresis assay.

The search for relevant target cells for human monitoring purposes has increased during the last few years. Cells such as sperm, buccal or nasal and gastric epithelium are being used. In this study, we report the use of exfoliated tear duct epithelial cells as a potential material for human biomonitoring studies, since these cells are a target for environmental pollutants. We employed the alkaline single cell gel electrophoresis (SCGE) assay to evaluate for differences in the basal level of DNA damage between young adults from the south (exposed mainly to high levels of ozone) and from the north (exposed principally to hydrocarbons) regions of Mexico City. We found an increase in DNA migration in tear duct epithelial cells from individuals who live in the southern part of the city compared to those living in the northern part. Moreover, young people who live in the southwest part of the city with the highest values of ozone presented the highest values of DNA damage. These results show the feasibility of using exfoliated tear duct epithelial cells in human biomonitoring studies.

Adolescent↗
PubMed2000

Exploitation of cellular signaling and regulatory pathways by human cytomegalovirus.

Human cytomegalovirus is a ubiquitous human pathogen that is the leading viral cause of birth defects. It also causes significant morbidity and mortality in both chemically and virally immunosuppressed individuals. Recent studies have begun to elucidate the interplay between this virus and its host cell on a molecular level. The interactions begin upon contact with the cell membrane, involve multiple processes including cell signaling, cell-cycle control and immune response mechanisms, and culminate in a productive infection.

Cell Cycle↗
PubMed1998

Elliptical versus circular erythrocyte marginal bands: isolation, shape conversion, and mechanical properties.

Differentiation of nucleated erythrocytes involves transformation from spheroids to flattened discoids to mature flattened ellipsoids. The marginal band (MB) of microtubules is required for this process and continues to play a role in maintaining mature ellipsoidal cell shape. One hypothesis for MB function is that cell ellipticity is generated and maintained by asymmetric application of force across a flexible, circular MB frame by the membrane skeleton or other transverse elements. This is based on an earlier finding that isolated erythrocyte MBs are much more circular than MBs in situ. However, our present studies of salamander erythrocyte MBs isolated by a detergent-based method challenge this hypothesis. Most of these isolated MBs are initially elliptical, even though they lack transverse material (= E-MBs). They can be stabilized in that form for long periods and can be converted experimentally into the circular form (= C-MBs) by extended incubation in isolation medium or by treatment with elastase or subtilisin. We have tested an alternative hypothesis for generation and maintenance of ellipsoidal MBs, one based on intrinsic differential bending resistance and supported by construction of models. Using laser microsurgical transection to compare mechanical responses of isolated E-MBs and C-MBs, we have found their behavior to be quite different. Whereas C-MBs linearize, most E-MBs do not, instead retaining considerable curvature. These results are incompatible with the differential bending resistance hypothesis, which predicts both C-MB and E-MB linearization. However, they are consistent with a third model, in which material bound to the MB stabilizes it in the mature ellipsoidal form, and indicate that the mechanism for maintenance of MB ellipticity differs from that involved in its generation.

Actins↗
PubMed1997

Mitogen-activated protein kinase-mediated Fas apoptotic signaling pathway.

Ligation of the cell surface receptor Fas/APO-1 (CD95) by its specific ligand or by anti-Fas antibodies rapidly induces apoptosis in susceptible cells. To characterize the molecular events involved in Fas-induced apoptosis, we examined the contribution of two subgroups of the mitogen-activated protein (MAP) kinase family, the Jun kinases or stress-activated protein kinases (JNKs/SAPKs) and the extracellular signal-regulated kinases (ERKs), in a Fas-sensitive neuroblastoma cell line. Here we show that both JNK and ERK protein kinases were activated upon Fas crosslinking through a Ras-dependent mechanism. Interference with either the JNK or ERK pathway by ectopic expression of dominant-interfering mutant proteins blocked Fas-mediated apoptosis. ERK activation was transient and associated with induced expression of the Fas receptor. In contrast, JNK activation was sustained and correlated with the onset of apoptosis. These data indicate that the ERK and the JNK groups of MAP kinases cooperate in the induction of cell death by Fas. Inhibition of Fas killing by an interleukin 1beta-converting enzyme (ICE)-like protease inhibitor peptide did not modify Fas-induced JNK activation upon Fas ligation. In contrast, changes in Bcl-2 level due to expression of sense and antisense vectors influenced the sensitivity to Fas killing and Fas-induced JNK activation.

Apoptosis↗
PubMed1997

Evolution of resistance to metronidazole and clarithromycin in Helicobacter pylori clinical isolates from Spain.

The aim of this study was to determine the frequency of resistance to amoxycillin, tetracycline, metronidazole and clarithromycin in 282 Helicobacter pylori clinical isolates from Spain and to evaluate the evolution of resistance over the five years of this study. The overall percentage of resistance was 19.9% for metronidazole and 3.5% for clarithromycin. Resistance to metronidazole rose from 9% in 1991 to 21.6% in 1995, although 33.3% resistance was found in 1993. Clarithromycin resistance was not detected in 1991 or 1992 and the rate was 4%, 3.4% and 4.4% in 1993, 1994 and 1995, respectively. No amoxycillin or tetracycline resistance was found.

Adolescent↗
PubMed1996

Endometrial ossification successfully treated by hysteroscopic resection.

BACKGROUND: Endometrial ossification is a rare condition. The common feature in most reported cases is a previous history of abortion and retention of fetal bones. Few cases of endometrial ossification can be explained by osseous metaplasia. Clinical presentation may include abnormal vaginal bleeding or discharge, dysmenorrhoea, pelvic pain, and secondary infertility. Hysterectomy or dilation and curettage have been the usual therapeutic methods used. Recently, some cases have been treated by means of hysteroscopic resection. CASE: We report a case of endometrial ossification in a woman who presented with dysmenorrhoea, dyspareunia and pelvic pain. The patient had a pregnancy voluntarily terminated at 16 weeks. Five subsequent routine annual gynaecological exams, including ultrasonographies, were normal. A new gestation was also voluntarily terminated at 6 weeks. One month later the patient started with clinical manifestations. Ultrasonograms performed 4 months after the second abortion revealed a strong uterine echogenic band. Bone tissue was successfully removed by hysteroscopic resection. CONCLUSION: This case adds further evidence favouring new bone formation in the uterus as a pathogenic mechanism for endometrial ossification and illustrates the feasibility of hysteroscopic treatment for this condition.

Abortion, Induced↗
PubMed1996

Effect of gas density on respiratory sounds.

The generation of normal lung sounds by turbulent air flow has been questioned because gas density appears to have only a minor effect. We studied whether gas density has a greater influence on lung sounds at higher frequencies than traditionally measured. Six healthy adult men breathed air followed by a mixture of 80% helium and 20% oxygen (He-O2) at a target flow of 1.5 L/s. Flow and sounds at the trachea and posterior right lower lobe were simultaneously acquired by computer. Fourier analysis was applied to sounds at target flow +/- 0.2 L/s. Average power spectra were computed for each recording site, respiratory phase, and respired gas. He-O2 reduced the power of inspiratory lung sounds below 300 Hz by only 1.7 +/- 1.5 dB whereas power between 300 and 600 Hz was reduced by 4.6 +/- 1.4 dB (p<0.05). Tracheal sound power was reduced less consistently but all subjects showed an upward frequency shift in power maxima on He-O2, similar to formant shifts observed in helium speech. Our findings suggest that flow turbulence is the major determinant of lung sounds at higher frequencies. Current instruments for auscultation and recording of respiratory sounds may have to be modified to optimize their response in this higher frequency range.

Adult↗
PubMed1996

Lung sound spectra at standardized air flow in normal infants, children, and adults.

To investigate the effect of age and body size on normal lung sounds, we studied 10 newborn infants within 3 d after birth, nine children between 6 to 8 yr, and 10 adults between 25 and 37 yr of age. Lung sounds were recorded with a contact transducer over the posterior right lower lobe, and air flow was measured at the mouth. Computer analysis provided average power spectra of lung sounds at flows of 15 ml/s/kg. In children and adults measurements were also made at flows of 30 ml/s/kg. Lung sounds were referenced to background noise, measured at zero air flow. The spectra in infants contained less power below 300 Hz compared with children and adults, resulting in significantly higher quartile and spectral edge frequencies. Resonances of the thoracic cavity may explain some of the differences among the study groups. Sound attenuation above 300 Hz was similar at all ages. At increased air flows, lung sounds in children and adults were above background noise at frequencies as high as 2,000 Hz. High-frequency expiratory lung sounds of low intensity were present in all children and in eight of 10 adults at increased flows. Normal lung sounds of low intensity are present above traditionally accepted frequency limits and warrant further investigation.

Adult↗
PubMed1995

[Role of anticholinergic agents in the treatment of cystic fibrosis].

A significant proportion of patients with cystic fibrosis (CF) demonstrate increased airways hyperreactivity, a feature that has been well documented by several authors. This bronchial lability is more pronounced in those with more severe and advanced lung disease. Several mechanisms for this increased airways responsiveness have been proposed such as chronic inflammation with impairment of mucosal permeability, increase in amount of bronchial secretions, systemic autonomic abnormality, increase in incidence of atopy and airway narrowing and changes in airway geometry induced by chronic inflammation. Several studies have assessed the change in FEV1 after beta-agonist or anticholinergic therapy in CF patients and there are studies in which the effect of the combination of drugs was tested. In a group of young CF patients, we found on average a 7% increase in FEV1 after salbutamol and a 10% improvement after ipratropium bromide (IB). After inhaling both drugs, there was a 17% increase in FEV1 from baseline. There were also significant changes in static volumes and airway-resistance measurements when salbutamol and IB were administered in combination. The influence of pretreatment of either normal saline, salbutamol or ipratropium bromide with methacholine was evaluated by Avital and co-workers in a double-blind crossover study. They found an increase in PC20 without a change in baseline FEV1 following salbutamol and an even greater change after IB. These results suggest that the adrenergic agent altered the smooth muscle contractile mechanism, and that muscarinic pathway appears to be important in the pathogenesis of expiratory airflow obstruction in some CF patients. The mechanisms of this cholinergic sensitivity are unclear.(ABSTRACT TRUNCATED AT 250 WORDS)

Albuterol↗
PubMed1995

Drug management of noninfective complications of cystic fibrosis.

Cystic fibrosis (CF) is the commonest lethal hereditary disease in Caucasians. The disease involves a gene mutation located at the long arm of chromosome 7, and more than 300 mutations have been identified. CF is a systemic illness affecting the upper respiratory tract and airways, sweat and salivary glands, pancreas, gastrointestinal tract, liver and male reproductive system. The course is highly variable depending on the specific molecular abnormalities in the mutant gene. The current approach to therapy now involves the use of: (i) chest physiotherapy; (ii) bronchodilators when there is evidence of airways hyperreactivity; (iii) oral and intravenous antibiotics for acute pulmonary exacerbations and aerosolised antibiotics for prevention; (iv) recombinant human deoxyribonuclease I (dornase alfa) to promote airways clearance; (v) amiloride to improve sputum viscosity; (vi) pancreatic enzyme replacement therapy along with nutritional support and supplements; (vi) vitamins; and (vii) ursodeoxycholic acid in selected patients. The use of antiprotease and anti-inflammatory agents has been shown to be useful in preventing the damage secondary to chronic lung infection. In patients with severely impaired lung function, lung transplantations have been performed with good results. Finally, it seems probable that lung disease in CF patients will be ameliorated or prevented in the future with early gene therapy, using vectors such as recombinant adenoviruses, adeno-associated virus, lipofection or retrovirus. However, this require extensive basic and clinical research.

Cystic Fibrosis↗