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Biomedical subjects

L Martinez

Publications and source records attributed to L Martinez.

At least 37 records · Page 2Linked to original sources
PubMed2004

Expression of integrin fraction and adhesion molecules on human granulosa cells and its relation with oocyte maturity and follicular steroidogenesis.

PURPOSE: To study the correlation between the expression of integrin fractions and adhesion molecules on granulosa cells (GC) and follicular development. METHODS: GC and follicular fluid (FF) were obtained at oocyte retrieval for ICSI. Expression of adhesion molecules on GC was studied by flow cytometry. Statistics were evaluated using the Student t test and simple linear regression analysis. RESULTS: alpha5 integrin fraction was significantly (p < 0.01) higher, while alpha6 fraction and CD9 were significantly (p < 0.01 and p < 0.001, respectively) lower in GC from FF with metaphase II oocytes. A direct significant correlation was observed between FF progesterone and the alpha5 expression on GC (r = 0.54). In contrast, an inverse significant correlation was observed between FF progesterone level and the expression of alpha6 and CD9 (r = -0.40 and -0.41, respectively). CONCLUSIONS: The expression pattern for integrin fractions and adhesion molecules may be of predictive value in assessing the state of differentiation of the human follicle.

Estradiol↗
PubMed2004

Variants of U1 small nuclear RNA assemble into spliceosomal complexes.

In this study, the existence of additional U1 snRNA variants in the posterior silk gland of the Bombyx mori Nistari strain from India was investigated. Three new U1 variants were detected. One of the new isoforms (U1 SG1) was found to be preferentially assembled into high molecular weight spliceosomal complexes in comparison with the total cellular lysate RNA control. Structural and nucleotide differences were examined in these new isoforms and compared with the previously reported U1 variants. Free energy (Delta G) values for the entire U1 snRNA secondary structures as well as the individual stem/loops (I, II, III and IV) domains of the isoforms were estimated to determine their structural stability.

Animals↗
PubMed2003

Aggressive conservative treatment of esophageal perforations in children.

BACKGROUND/PURPOSE: In contrast with adult patients in whom surgical closure of the defect is preferred, nonoperative treatment has been the usual approach for esophageal perforation (EP) in children. This report aims to assess whether this strategy stands the passage of time. METHODS: We reviewed retrospectively the charts of 17 patients aged 5.3 +/- 0.9 years (mean +/- SD) treated at our institution for EP between 1991 and 2001. RESULTS: Nineteen episodes of EP were caused by stricture dilation in 9 cases, foreign body extraction in 3, and blunt trauma and sclerosis of varices in 2 cases each. The remaining child had multiple gastrointestinal perforations in the course of chemotherapy for leukemia. Vigorous treatment, consisting of nasopharyngeal aspiration, wide spectrum antibiotics, prompt drainage of effusions and either parenteral or infraesophageal nutritition, was implemented immediately after diagnosis. Perforations were closed without direct surgery in 18 of 19 episodes (16 of 17 children). One or more pleural drains were inserted in 12 cases, and pericardial drainage was required once. Seven gastrostomies, 2 jejunostomies, and one esophagostomy were performed. Several major abdominal operations were necessary to repair concomitant lesions in a child who sustained severe blunt abdominal trauma and in the patient with leukemic perforations. All patients survived, and all recovered esophageal function. However, 2 with intractable lye strictures ultimately required esophageal replacement. The only patient in whom a direct approach for esophageal necrosis due to variceal endosclerosis was unavoidable, lost her organ and had a retrosternal colonic interposition after a successful portosystemic shunt. Excluding patients with other concomitant lesions and the patient who underwent surgery, median length of stay was 11 days (range, 6 to 47). CONCLUSIONS: Prompt and aggressive nonoperative treatment of esophageal perforations in children allows survival with conservation of the organ in most cases and remains, in the authors' hands, the first therapeutic choice at this age.

Abdominal Injuries↗
PubMed2003

Evaluation of the Performance of the THOR-alpha Dummy.

Six European laboratories have evaluated the biomechanical response of the new advanced frontal impact dummy THOR-alpha with respect to the European impact response requirements. The results indicated that for many of the body regions (e.g. shoulder, spine, thorax, femur/knee) the THOR-alpha response was close to the human response. In addition, the durability, repeatability and sensitivity for some dummy regions have been evaluated. Based on the tests performed, it was found that the THOR-alpha is not durable enough. The lack in robustness of the THOR-alpha caused a problem in completing the full test program and in evaluating the repeatability of the dummy. The results have demonstrated that the assessment of frontal impact protection can be greatly improved with a more advanced frontal impact dummy. Regarding biofidelity and injury assessment capabilities, the THOR-alpha is a good candidate however it needs to be brought up to standard in other areas. Based on the results obtained recommendations were defined for the improvement of the THOR-alpha dummy.

Journal Article↗
PubMed2001

Altered content and modulation of soluble guanylate cyclase in the cerebellum of rats with portacaval anastomosis.

It is shown that the glutamate-NO-cGMP pathway is impaired in cerebellum of rats with portacaval anastomosis in vivo as assessed by in vivo brain microdialysis in freely moving rats. NMDA-induced increase in extracellular cGMP in the cerebellum was significantly reduced (by 27%) in rats with portacaval anastomosis. Activation of soluble guanylate cyclase by the NO-generating agent S-nitroso-N-acetyl-penicillamine and by the NO-independent activator YC-1 was also significantly reduced (by 35-40%), indicating that portacaval anastomosis leads to remarkable alterations in the modulation of guanylate cyclase in cerebellum. Moreover, the content of soluble guanylate cyclase was increased ca. two-fold in the cerebellum of rats with portacaval anastomosis. Activation of soluble guanylate cyclase by NO was higher in lymphocytes isolated from rats with portacaval anastomosis (3.3-fold) than in lymphocytes from control rats (2.1-fold). The results reported show that the content and modulation of soluble guanylate cyclase are altered in brain of rats with hepatic failure, resulting in altered function of the glutamate-NO-cGMP pathway in the rat in vivo. This may lead to alterations in cerebral processes such as intercellular communication, circadian rhythms, including the sleep-waking cycle, long-term potentiation, and some forms of learning and memory.

Animals↗
PubMed2001

Architecture and function of the gastroesophageal barrier in the piglet.

We describe the anatomy and function of the gastroesophageal barrier in the piglet. Male piglets underwent dissection (N = 6) and gastroesophageal muscle layer histometry (N = 6). Sedated, nonintubated animals (N = 13) underwent four-probe perfusion esophageal manometry and the pressure profiles were related to the muscular thickness in the four quadrants. Hiatal and gastroesophageal anatomy are similar to our own. The muscle is thicker at the point where the clasp (on the right side) and sling fibers (on the left) concentrate. The pressure profiles were axially and radially asymmetric in coincidence with the thickness variations of the corresponding muscle layers. Sphincteric pressure was recorded as a plateau, whereas diaphragmatic crural pressure appeared as phasic oscillations in synchrony with respiration. The sphincter relaxed upon deglutition. In conclusion, the gastroesophageal structure and physiology are so similar in men and piglets that piglets are excellent models for research in this area.

Animals↗
PubMed2001

Chromatin status in human ejaculated spermatozoa from infertile patients and relationship to seminal parameters.

The aim of this study was to evaluate the chromatin status in different groups of patients. Five groups of men were selected: pre-vasectomy; male factor infertility; varicocele; immunological male infertility; and idiopathic infertility. Chromatin status was evaluated using flow cytometry after staining the DNA with the fluorochrome propidium iodide. Differences were observed in the state of sperm chromatin between the male factor and varicocele groups with respect to the others. These two groups presented poorer quality chromatin, as evidenced fundamentally by a lower degree of condensation. These deficiencies in chromatin status were usually accompanied by alterations in the other standard parameters of semen analysis. Individuals who are infertile due to male factor and those presenting varicocele have spermatozoa with less condensed chromatin which might, in part, explain their sterility.

Chromatin↗
PubMed2001

WHP/ISBRA study on state and trait markers in alcoholism.

This article represents the proceedings of a symposium at the 2000 ISBRA Meeting in Yokohama, Japan. The chair was Boris Tabakoff. The presentations were (1) Overview of the WHO/ISBRA study on state and trait markers in alcoholism, by Boris Tabakoff; (2) Biochemical markers of acute and chronic drinking: Results of the WHO/ISBRA study, by Anders Helander; (3) The impact of country of recruitment and body mass index on biological marker dose-response curves in the WHO/ISBRA Study, by Kate M. Conigrave; (4) Relationship of body water to carbohydrate-deficient transferrin measures, by Larry Martinez; and (5) Platelet adenylyl cyclase activity as a trait marker of alcohol dependence, by Paula L. Hoffman.

Adenylyl Cyclases↗
PubMed2000

Mini-review: history of organized teratology information services in North America.

A history of the Organization of Teratology Information Services (OTIS) is presented in context of the history of teratology information services. During the late 1970s, teratology information services grew out of the need for current and accurate information about fetal effects of environmental exposures in pregnancy. Over the next decade, teratology information services networked and collaborated, developing their own professional organization. A description of the activities of OTIS is described.

Female↗
PubMed2000

Identification of known and novel genes in activated monocytes from patients with rheumatoid arthritis.

OBJECTIVE: To define gene activation patterns of monocytes (MO) in patients with rheumatoid arthritis (RA). METHODS: A complementary DNA (cDNA) library was constructed from first-leukapheresis MO obtained from an RA patient with active disease; 32P-labeled cDNA from first-leukapheresis MO (activated pool) and third-leukapheresis MO (nonactivated pool) were used as probes for differential hybridization. Reverse transcriptase-polymerase chain reaction (RT-PCR) was used to assess gene activation in MO from an additional 26 RA patients and 6 normal controls. RESULTS: Subtraction of genes from first- and third-leukapheresis MO resulted in 482 differentially expressed clones. In first-leukapheresis MO, these clones included the following: 1) interleukin-1alpha (IL-1alpha), IL-1beta, IL-6, tumor necrosis factor alpha, growth-related oncogene alpha (GROalpha)/melanoma growth-stimulatory activity, macrophage inflammatory protein 2/GRObeta, ferritin, alpha1-antitrypsin, lysozyme, transaldolase, Epstein-Barr virus-encoded RNA 1 (EBER-1)/EBER-2-associated-protein, thrombospondin 1, an angiotensin receptor II (ATRII) C-terminal homolog, and RNA polymerase II elongation factor (elongin); 2) two clones homologous to functionally undefined genes (BSK-67 and BSK-83); and 3) three unknown cDNA sequences (BSK-66, 80, 89). In third-leukapheresis MO, the clones included differentiation genes (HOX-B3, thymosin-beta4, PU.1, glucocerebrosidase, MEL-18, and glucose-6-phosphate dehydrogenase) and 3 unknown/functionally undefined sequences. Differential expression of most genes from the activated pool was confirmed in leukapheresis samples from 2 additional RA patients. In MO from RA patients, not only were IL-1beta and the ATRII homolog significantly overexpressed (maximum 36-fold), but also 4 of the unknown/functionally undefined genes (maximum 102-fold). Notably, messenger RNA levels of BSK-89 correlated positively with the erythrocyte sedimentation rate (ESR), whereas those of BSK-83 correlated negatively with the ESR and C-reactive protein level. CONCLUSION: The combined strategy of gene subtraction and semiquantitative RT-PCR may allow the definition of MO activation patterns during different disease phases (including therapy-induced remission) and the identification of novel MO genes with pathogenetic relevance in RA.

Adult↗
PubMed2000

Photophysical studies on melatonin and its receptor agonists.

Previous work has demonstrated that melatonin inhibits the growth of both dermal and uveal melanoma cells. Recent clinical trials have found that melatonin is an efficacious treatment for metastatic dermal melanoma. The goal of this study was to provide further insight into the oncostatic mechanism(s) of melatonin. The inhibition of the growth of uveal melanoma cells is dose-dependent (0.1-10 nM) within the range of endogenous melatonin concentrations (2 nM) found in the human aqueous humor. We know that this inhibition of growth is receptor-mediated, at least in part, because uveal melanoma cell growth was also blocked by the agonists of melatonin receptors. There are two known membrane receptors for melatonin (Mel(1a) and Mel(1b)) and one known nuclear receptor (Mel2). To determine if singlet oxygen production and/or quenching contributed to the growth inhibition of melatonin, we examined the photophysical properties of melatonin and its agonists. Using flash photolysis, we determined that melatonin and its membrane receptor agonist 6-chloromelatonin (Mel(1a-b), Lilly, Indianapolis, IN) produced very little singlet oxygen (psidelta = 0.073 and psidelta = 0.01, respectively). There was no detectable singlet oxygen phosphorescence at 1,270 nm for the nuclear receptor agonist CG-52608 (Mel2, Novartis, Basel, Switzerland). In contrast, the agonist of the Mel(1b) receptor, S-20098 (Servier, Paris, France), produced singlet oxygen with a quantum efficiency of psidelta = 0.34. Singlet oxygen was quenched by melatonin and 6-chloromelatonin at approximately the same rate (6.1 x 10(7) M(-1)s(-1) and 6.0 x 10(7) M(-1)s(-1) in CD3OD), while the rate of quenching for the nuclear receptor agonist CG-52608 and membrane receptor agonist S-20098 was less (2.2 x 10(7) M(-1)s(-1) and 1.5 x 10(7) M(-1) s(-1), respectively). It appears that the production of singlet oxygen by melatonin would not be sufficient to directly block the proliferation of melanoma cells, but may activate gene products that could contribute to the oncostatic effect.

Acetamides↗
PubMed2000

Photochemical studies on xanthurenic acid .

The tryptophan metabolite xanthurenic acid (Xan) has been isolated from aged human cataractous lenses. The photophysical properties of Xan were examined to determine if it is a potential chromophore for age-related cataractogenesis. We found that Xan produces singlet oxygen (psi delta = 0.17 in CD3OD) with the same efficiency as the lenticular chromophore N-formyl kynurenine and quenches singlet oxygen at a rate similar (2.1 x 10(7); CD3OD) to other tryptophan metabolites found in the eye. As the mechanisms of induction of cataracts may also involve redox reactions, the interactions of hydrated electrons (e(aq)-), the azide radical (N3*) and hydroxyl radical (OH*) with Xan were studied using the technique of pulse radiolysis. The reaction rate constants of e(aq)-, N3* and OH* with Xan were found to be of the same order of magnitude as other tryptophan metabolites. The rate constant for reaction of Xan with e(aq)- solvated electrons was found to be diffusion controlled (k = 1.43 x 10(10) M(-1) s(-1); the reaction with N3* was very fast (k = 4.0 x 10(9) M(-1) s(-1)); and with OH* was also near diffusion controlled (k = 1.0 x 10(10) M(-1) s(-1)). Superoxide O2*- production by irradiated Xan in methanol was detected by electron paramagnetic resonance and substantiated by determining that the enhanced rate of oxygen consumption of Xan irradiated in the presence of furfuryl alcohol was lowered by superoxide dismutase.

Cataract↗
PubMed2000

[Hantavirus pulmonary syndrome in southern Argentina].

Andes virus was identified in 1995 as the etiologic agent of Hantavirus Pulmonary Syndrome (HPS) in Southern Argentina. We describe herein the main clinical characteristics of 25 HPS confirmed cases acquired in this area between 1993 and September 1999. The mean age was 34 years (range 11-70), with 72% males. Clinical characteristics were similar to those previously reported for Sin Nombre virus (SNV) cases. However, in this group of patients we also observed conjuntival injection in 10/25 (42%), facial flushing in 8/25 (33%), pharyngeal congestion in 7/25 (29%) and petechiae in 3/25 (12%). On the other hand, BUN was increased in 83% of cases (mean 0.77 g/l range 0.31-2.01). Mean serum creatinine concentration was 26.8 mg/l (range: 8.1-110 mg/l) with serum creatinine being higher than 20 mg/l in 8/15 patients (53%). Urinalysis was abnormal in 12/12 cases and was characterized by presence of proteins, red blood cells and granular casts. Aminotransferases were increased in 90% of cases with levels 5-10 times over normal values in 50% of cases. Serum creatine kinase concentration was elevated in 11/14 cases. Two patients required hemodialysis. Case fatality rate was 44% (11/25) and 10 of these cases died among the first 10 days of illness. Mononuclear myocarditis was observed in two cases, a finding that has not been reported for SNV cases. During the 1996 HPS outbreak in Southern Argentina due to Andes virus, there were epidemiological and molecular evidences of person-to-person transmission, a feature not previously shown for other members of the hantavirus genus. These data would also be indicative of some distinctive clinical characteristics of HPS caused by Andes virus, with more frequent renal involvement than in SNV cases.

Adolescent↗
PubMed1999

Heterologous gene expression in a membrane-protein-specific system.

We have constructed an expression system for heterologous proteins which uses the molecular machinery responsible for the high level production of bacteriorhodopsin in Halobacterium salinarum. Cloning vectors were assembled that fused sequences of the bacterio-opsin gene (bop) to coding sequences of heterologous genes and generated DNA fragments with cloning sites that permitted transfer of fused genes into H. salinarum expression vectors. Gene fusions include: (i) carboxyl-terminal-tagged bacterio-opsin; (ii) a carboxyl-terminal fusion with the catalytic subunit of the Escherichia coli aspartate transcarbamylase; (iii) the human muscarinic receptor, subtype M1; (iv) the human serotonin receptor, type 5HT2c; and (v) the yeast alpha mating factor receptor, Ste2. Characterization of the expression of these fusions revealed that the bop gene coding region contains previously undescribed molecular determinants which are critical for high level expression. For example, introduction of immunogenic and purification tag sequences into the C-terminal coding region significantly decreased bop gene mRNA and protein accumulation. The bacteriorhodopsin-aspartate transcarbamylase fusion protein was expressed at 7 mg per liter of culture, demonstrating that E. coli codon usage bias did not limit the system's potential for high level expression. The work presented describes initial efforts in the development of a novel heterologous protein expression system, which may have unique advantages for producing multiple milligram quantities of membrane-associated proteins.

Amino Acid Sequence↗
PubMed1999

Late biliary complications in pediatric liver transplantation.

PURPOSE: The aim of this study was to review the biliary complications occurring in late follow-up after liver transplantation in children. METHODS: The medical records of 135 children who received orthotopic liver transplantations (OLT) and had graft survival of more than 1 year were reviewed. Technical variants using a reduced-size graft were applied in 32 (23.7%). For biliary reconstruction, 15 patients had choledochocholedochostomy and 120 a Roux-en-Y loop. Biliary reoperation in the early post-OLT period was needed in 24 patients (17.7%). Routine checking of liver function and duplex Doppler ultrasonography (DDS) were performed during the follow-up period, which averaged 58 months. Late biliary complication was defined as that occurring after the first hospital discharge. RESULTS: Late biliary complications occurred in 18 children (13.3%); 16 showed symptoms or analytical disturbances in liver function tests. The Diagnoses included uncomplicated cholangitis (n = 6), anastomotic biliary stricture (n = 7), ischaemic damage of the biliary tree (n = 3) including one late (28 months) hepatic artery thrombosis leading to an intrahepatic biloma. and bile leak after T-tube removal (n = 2). The six children with uncomplicated cholangitis had no repeat episodes in follow-up despite persistent aerobilia. Six patients affected by anastomotic strictures were treated successfully with percutaneous dilatation and, if present, stone removal. Persisting dysfunction and cholangitis occurred in one case affected by ischaemic biliary disease. Biliary leaks after T tube removal settled spontaneously. Risk factors for late biliary complications were determined. There was no relation to the cold ischaemia time, type of graft or biliary reconstruction, or previous early post-OLT biliary reoperation. Aerobilia (affecting 21.5% of OLT patients) was related to cholangitis (P = .001). CONCLUSIONS: Anastomotic strictures, reflux of intestinal contents via the Roux-en-Y loop, and residual ischaemic damage led to late biliary complications in 12% of paediatric OLT patients. Evidence of biliary dilatation on DDS may be delayed in anastomotic strictures; in these cases the results of percutaneous treatment were excellent. Children with aerobilia have and increased risk of cholangitis.

Analysis of Variance↗
PubMed1999

Safe biotechnology 9: values in risk assessment for the environmental application of microorganisms. The Safety in Biotechnology Working Party of the European Federation of Biotechnology.

Risk assessment for the deliberate release of microorganisms into the environment is traditionally carried out on a case-by-case basis. In a similar approach to that used when assessing human pathogenicity, we propose an alternative approach by introducing risk classes to facilitate or complement this type of risk assessment. These consider several sets of scenarios that address the different values that need to be protected. Examples of this approach include risk-class definitions for soil fertility and biodiversity.

Bacteria↗