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Biomedical subjects

J Muñoz

Publications and source records attributed to J Muñoz.

At least 37 records · Page 2Linked to original sources
PubMed2002

Electrochemical platinum coatings for improving performance of implantable microelectrode arrays.

The formation and properties of electrochemical platinum films grown on platinum contacts contained in implantable flexible microelectrodes were investigated. The resulting platinum deposits were obtained by applying cyclic voltammetry to baths containing concentrations around 70 mM of chloroplatinic acid. A pre-activation step was necessary before the platinum-electroplating step in order to achieve good adhesive properties. The benefits of this process were ascribed to higher corrosion resistance, lower impedance and improved adhesion to the sputtered platinum. These improvements can make the application of this electrochemical technique highly useful for increasing the lifetime of implantable microelectrode arrays, such as cuff structures (IEEE Trans. Biomed. Eng. 40 (1993) 640). These medical devices, obtained by semiconductor technology could be used for selective stimulation of nerve fascicles, although, poor long-term performance has been achieved with them. The dissolution rate for platinum thin-film microelectrodes under fixed corrosion test conditions was 38.8 ng/C. Lower rates were observed for electroplated microelectrodes, obtaining a dissolution rate of 7.8 ng/C under analogous experimental ageing conditions. The corrosion behaviour of the electroplated platinum during stimulation experimental conditions was estimated by electrochemical impedance spectroscopy.

Biocompatible Materials↗
PubMed2002

Dietary influence of kefir on microbial activities in the mouse bowel.

AIMS: In this work the microflora present in kefir, a fermented milk product, was studied together with the effect of kefir administration on different groups of indigenous bacteria of mouse bowel. METHODS AND RESULTS: Kefir microflora was composed of lactic acid bacteria, acetic acid bacteria and yeasts. Yeast population was composed of Saccharomyces cerevisiae, S. unisporus, Candida kefir, Kluyveromyces marxianus and K. lactis. The streptococci levels in kefir treated mice increased by 10-fold and the levels of sulfite-reducing clostridia decreased by 100-fold. The number of lactic acid bacteria increased significantly. CONCLUSIONS: The administration of kefir significantly increased the lactic acid bacteria counts in the mucosa of the bowel. Ingestion of kefir specifically lowered microbial populations of Enterobacteriaceae and clostridia. SIGNIFICANCE AND IMPACT OF THE STUDY: This is the first long-term study about the effects of the kefir administration on the intestinal microflora of mice.

Animals↗
PubMed2002

Perceptual analysis in different voice samples: agreement and reliability.

The objective of this study was to estimate the agreement and reliability of voice evaluation by a group of expert listeners using the central portion of a sustained vowel and a fragment of connected speech as voice samples. Ratings were made using Wilson's Buffalo III Voice Screening Profile. Analysis showed that intraindividual listeners' agreement presented variability in the evaluation of both voice samples. In the evaluation of the central portion of the sustained vowel, interindividual listener agreement was moderate for breathiness, hyponasal resonance, and overall voice rating; in connected speech, agreement was moderate for most voice qualities (breathy, rough, high/low pitch, and hyponasal resonance). Finally, Wilson's Buffalo III Voice Screening Profile presented good reliability values for both voice samples, with overall voice rating achieving higher values (.90) than any other voice-quality variable.

Adult↗
PubMed2002

[Results of C1-C2 transarticular screw fixation in a series of 20 patients].

OBJECTIVE: C1-C2 transarticular fixation is an increasingly used surgical method of treating atlantoaxial instability. When properly performed, it can safely provide fusion rates near 100%, but techniques of fixation in this region allow only a small margin of error. We here report the results of C1-C2 transarticular fixation in a series of 20 patients in which different procedures were selected according to the presenting disorder in each case. METHODS: The study group included 9 men and 11 women with a mean age of 48 years (range 17 to 68 years). The causes of instabilities were rheumatoid arthritis in nine patients, type II and III Hangman's fracture of traumatic origin in nine (in association with other lesions in three cases), pseudoarthrosis after type II odontoid fracture in one, and type III complex C1 fracture in a patient with ankylosing spondylitis. Preoperative assessment included flexion and extension plain radiographs and computed tomography (CT) and magnetic resonance imaging (MRI) scans. Operations included transarticular screw fixation in all cases; in patients with rheumatoid arthritis it was associated with sublaminar fixation and bone grafting following Sonntag's technique in all but two cases. Postoperative results were evaluated in relation to the biomechanical stability and fusion was studied by flexion and extension radiographs and CT scans. Pain relief in patients with rheumatoid arthritis patients was assessed using a 0-10 visual analogic scale (V.A.S.). RESULTS: In the traumatic group, a consolidation of the fracture and radiologic stability was achieved in all cases. In patients with rheumatoid arthritis, pain improved in all but not the neurological deficit, and in all cases a C1-C2 biomechanical stability was reached despite interlaminar graft resorption in two (25%) cases. With respect to complications, a lesion of the vertebral artery occurred in one case, deviation of the screw in two cases, and breakage of the screw without clinical repercussion in two other cases. CONCLUSION: C1-C2 transarticular screw fixation was a useful technique to achieve satisfacory biomechanical stability in patients with atlatoaxial instability of both inflammatory and traumatic origin with a low rate of complications.

Adolescent↗
PubMed2001

[Clinical and epidemiological characteristics of persons newly diagnosed of HIV infection].

BACKGROUND: We describe the characteristics of people with a recent diagnosis of HIV infection. PATIENTS AND METHOD: Series of 126 new cases of HIV infection diagnosed in an infectious diseases Service. RESULTS: Sexual transmission was the commonest form of infection (74%). Fifteen percent of individuals were aged over 50 years and 16% were immigrants. A late diagnosis (stage C) accounted for 36% of cases and it was associated with being more than 50 years old (OR: 5.1; 95% CI: 1.6-16.8). CONCLUSIONS: It is necessary to implement HIV infection surveillance systems and to improve preventive services.

Adult↗
PubMed2001

Usefulness of route of transmission, absolute CD8+ T-cell counts, and levels of serum tumor necrosis factor alpha as predictors of survival of HIV-1-infected patients with very low CD4 + T-cell counts.

Potential cofactors of survival in HIV-1-infected patients with CD4+ T-cell counts of < or = 100 cells/microl were investigated. All 132 patients with CD4+ T-cell counts of < or = 100 cells/microl were selected from 416 patients included in an antiretroviral therapy cohort (1989-1999). Fifty of 54 deaths were due to AIDS. There were significant associations (P<0.05) between survival and CD8+ T-cell counts, clinical AIDS stage, risk group, and antiretroviral drug regimen after baseline, but only the use of protease inhibitors had an independent effect on survival (hazard ratio [HR], 0.096; 95% confidence interval [95%CI], 0.094-0.097). A substudy restricted to the cohort of 108 patients never exposed to PIs detected independent associations between survival and CD8+ T-cell counts (P=0.0016), experience with antiretroviral therapy before baseline (HR, 2.52; 95%CI, 1.31-4.82), sexual risk group for HIV infection (HR, 3.7; 95%CI, 1.92-7.12), and levels of serum tumor necrosis factor alpha (P=0.02). This study confirms that the use of PI-containing antiretroviral regimens strongly predicts survival of HIV-1-infected patients with very low CD4+ T-cell counts. When the study was restricted to patients never exposed to PIs, the parenteral route of disease transmission, high absolute CD8 + T-cell counts, and low serum levels of tumor necrosis factor alpha were independent predictors of survival in extremely advanced HIV-1 disease.

Acquired Immunodeficiency Syndrome↗
PubMed2001

A fish cell surface receptor defined by a mAb mediates leukocyte aggregation and deactivation.

Cell adhesion molecules play a key role in the inflammatory response. Selectins, integrins and immunoglobulin gene superfamily adhesion receptors mediate the different steps of leukocyte migration from the blood-stream towards inflammatory foci. In addition to their adhesive function, these receptors modulate major cellular processes such as cell activation, growth, differentiation and death. To characterise the fish molecules involved in cell adhesion, a panel of mAbs was raised by immunising mice with macrophages from the marine fish gilthead seabream (Sparus aurata L.). One of these mAbs, which we named anti-Aggregatin, was found to induce a rapid heterotypic aggregation of seabream leukocytes. Anti-Aggregatin defined a 140-kDa cell surface receptor which was highly expressed by macrophages and was up-regulated after co-stimulation with LPS and MAF. Functionally, the cell adhesion which occurred upon exposure to anti-Aggregatin required Ca(2+), an intact cytoskeleton and an active cell metabolism. More importantly, Aggregatin engagement resulted in strong inhibition of the phagocyte respiratory burst, although the cells showed neither loss of viability nor DNA fragmentation. The results are discussed in relation to the potential role of cell adhesion molecules in fish immune responses.

Animals↗
PubMed2001

Molecular pathology of endometrial hyperplasia and carcinoma.

Four different genetic abnormalities may occur in endometrioid adenocarcinomas of the endometrium (mircosatellite instability and mutations in the PTEN, k-RAS and beta-catenin genes), whereas nonendometrioid carcinomas of the endometrium often have p53 mutations and loss of heterozygosity on several chromosomes. Occasionally, a nonendometrioid carcinoma may develop as a result of dedifferentiation of a preexisting endometrioid carcinoma; in such a case, the tumor exhibits overlapping clinical, morphologic, immunohistochemical, and molecular features of the 2 types. The insaturation of microsatellite instability in endometrial carcinogenesis seems to occur late in the transition from complex hyperplasia to carcinoma, and it is preceded by progressive inactivation of MLH-1 by promoter hypermethylation. Moreover, the endometrioid adenocarcinomas that exhibit microsatellite instability show a stepwise progressive accumulation of secondary mutations in oncogenes and tumor suppressor genes that contain short-tandem repeats in their coding sequences. Mutations in the PTEN and k-RAS genes are also frequent in endometrioid adenocarcinomas of the endometrium, particularly in the tumors that exhibit microsatellite instability, whereas beta-catenin mutations do not seem to be associated with such a phenomenon.

Cytoskeletal Proteins↗
PubMed2001

Radicular involvement and medullary invasion from a malignant mesothelioma.

We present the case of a 57-year-old patient who had worked at a fiber-cement factory for 28 years. The patient developed an epithelioid-type pleural mesothelioma 5 years after retiring, after he was diagnosed with asbestosis. Only 5 months after the diagnosis of mesothelioma, a medullar section appeared to be totally invaded by a tumor in the medullar canal, thus causing paraplegia and affecting the bladder and anal sphincters. The patient underwent radiotherapy and chemotherapy, and achieved partial recovery, but died 9 months after the diagnosis.

Antineoplastic Combined Chemotherapy Protocols↗
PubMed2000

Chemical and rheological properties of an extracellular polysaccharide produced by the cyanobacterium Anabaena sp. ATCC 33047.

The cyanobacterium (blue-green alga) Anabaena sp. ATCC 33047 produces an exopolysaccharide (EPS) during the stationary growth phase in batch culture. Chemical analysis of EPS revealed a heteropolysaccharidic nature, with xylose, glucose, galactose, and mannose the main neutral sugars found. The infrared (IR) spectrum of EPS showed absorption bands of carboxylate groups. The average molecular mass of the polymer was 1.35 MDa. Aqueous dispersions at EPS concentrations ranging from 0.2% to 0.6% (w/w) showed marked shear-thinning properties (power-law behavior). Linear dynamic viscoelastic properties showed that the elastic component was always higher than the viscous component. Viscous and viscoelastic properties demonstrated the absence of conformational changes within the concentration range studied. Stress-growth experiments revealed that 0.4% and 0.6% (w/w) EPS dispersions showed thixotropic properties. A detailed comparison of the linear dynamic viscoelasticity, transient flow, and decreasing shear rate flow curve properties was made for 0.4% (w/w) dispersions of xanthan gum (XG), Alkemir 110 (AG), and EPS. Viscoelastic spectra demonstrated that the EPS dispersion turned out to be more "fluidlike" than the AG and XG dispersions. The flow indexes indicated that the EPS dispersion was less shear-sensitive than that of XG, showing essentially the same viscosity, that is, >50 s(-1). The fact that viscosities of EPS and AG dispersions were not substantially different within the shear-rate range covered must be emphasized, in relation to EPS potential applications. The rheological behavior of EPS dispersions indicates the formation of an intermediate structure between a random-coil polysaccharide and a weak gel.

Anabaena↗
PubMed2000

Blood cells of sea bass (Dicentrarchus labrax L.). Flow cytometric and microscopic studies.

Studies of fish blood cells made to date presented numerous problems derived from both the nomenclature and the techniques used. A combination of quantitative and morphological methods is needed if the classification of fish blood cells is to advance from it present provisional state. The aim of the present paper was first to isolate sea bass blood cell populations by flow cytometry and second to characterize then microscopically. Blood cell populations from sea bass (Dicentrarchus labrax L.) were isolated according to their FSC (size) and SSC (granularity) properties by flow cytometry. The isolated populations were then processed for light and transmission and scanning electron microscopic characterization. Sea bass blood leukocytes isolated by flow cytometry consisted of two main cell subpopulations. Subsequent microscopic study of these cells revealed that the first subpopulation was composed of small cells (3-5 microm) of low granularity and consisted of thrombocytes and lymphocytes whereas, the second subpopulation was formed of 6-9 microm sized cells of high granularity consisting of granulocytes and monocyte/macrophages. The combined use of flow cytometry and electron microscopy makes it possible to characterize the different cell types present in sea bass peripheral blood with a high degree of certainty. Although sea bass basically follows the common vertebrate hematological pattern, significant modifications such as the presence of circulating immature erythrocytes, plasma cells and monocyte/macrophages and different forms of thrombocytes can be established with respect to this pattern.

Animals↗
PubMed2000

Effect of propranolol on the factors promoting bacterial translocation in cirrhotic rats with ascites.

Bacterial translocation appears to be an important mechanism in the pathogenesis of spontaneous infections in cirrhosis. Cirrhotic patients are commonly treated with beta-adrenoceptor blockers, but the impact of this treatment in the factors promoting bacterial translocation has not been investigated. This study was aimed at investigating in cirrhotic rats with ascites the effect of propranolol on intestinal bacterial load, transit, and permeability of the bowel and on the rate of bacterial translocation. Bacterial translocation to mesenteric lymph nodes and intestinal bacterial overgrowth, permeability (urinary excretion of (99m)Tc-diethylenetriaminepentaacetic acid [(99m)Tc-DTPA]), and transit (geometric center ratio of (51)Cr) were assessed in 29 rats with carbon tetrachloride (CCl(4)) cirrhosis and 20 controls. These variables were then measured in 12 placebo- and in 13 propranolol-treated ascitic cirrhotic rats. Bacterial translocation was present in 48% of the cirrhotic rats and in none of the controls. Cirrhotic rats with intestinal bacterial overgrowth had a significantly higher rate of translocation and slower intestinal transit than those without it. Among the 15 rats with overgrowth and a (99m)Tc-DTPA excretion greater than 10%, 15 had translocation and 2 had bacterial peritonitis. Only 1 of the 14 rats with either intestinal overgrowth or a (99m)Tc-DTPA excretion greater than 10% presented translocation. Compared with the placebo group, propranolol-treated animals had significantly lower portal pressure, faster intestinal transit, and lower rates of bacterial overgrowth and translocation. In ascitic cirrhotic rats, bacterial translocation results from intestinal overgrowth and severe damage to gut permeability. In this setting, intestinal overgrowth is associated with intestinal hypomotility. Propranolol accelerates the intestinal transit, decreasing the rates of bacterial overgrowth and translocation.

Animals↗
PubMed2000

Critical factors in chitin production by fermentation of shrimp biowaste.

Factors affecting Lactobacillus fermentation of shrimp waste for chitin and protein liquor production were determined. The objective of the fermentation is medium conditioning by Lactobacillus through production of proteases and lowering of the pH. The efficiency was tested by conducting fermentation of biowaste in 1-1 beakers with or without pH adjustment using different acids. Addition of 5% glucose to the biowaste supported the growth of lactic acid bacteria and led to better fermentation. Among four acids tested to control pH at the start and during fermentation, acetic acid and citric acid proved to be the most effective. In biowaste fermented with 6.7% L. plantarum inoculum, 5% glucose, and pH 6.0 adjusted with acetic acid, 75% deproteination and 86% demineralization was achieved. Replacement of acetic acid by citric acid gave 88% deproteination and 90% demineralization. The fermentation carried out in the presence of acetic acid resulted in a protein fraction that smelled good and a clean chitin fraction.

Acetic Acid↗