Biomedical subjects

S Gonzalez

Publications and source records attributed to S Gonzalez.

At least 55 records · Page 3Linked to original sources

PubMed1999

Transmission Electron Microscopy Characterization and Application of Sol-Gel Membranes.

: Using standard square mesh grids as supports, we have prepared sol-gel membranes from a functionalized silane precursor, bis[3-(triethoxysilyl)propyl]tetrasulfide in various organic solvents. These mesh-supported membranes allow direct characterization of their microstructure and morphology by transmission electron microscopy (TEM). Homogeneous membranes without prominent microstructural features (or featureless) at nanometer scale were obtained from dimethyl formamide (DMF), isopropanol, and butanol solutions. However, highly porous membranes were produced from DMF and ethylene glycol binary system. Heterogeneous membranes filled with nanoparticles were formed from dimethyl sulfoxide solution. The featureless sol-gel membranes with tunable performances provide a useful alternative as supporting films for TEM applications.

Journal Article↗

PubMed1999

Susceptibility to ankylosing spondylitis is independent of the Bw4 and Bw6 epitopes of HLA-B27 alleles.

We have characterized HLA-B27 alleles in a sample of the population from the Azores (n=46) with the aim of investigating the contribution of different subtypes to ankylosing spondylitis (AS). The study was carried out using PCR-SSOP and in some samples genomic sequencing was conducted. Some significant new finding have arisen from this study. First, B*2705,B*2702,B*2703,B*2707 and B*2708 alleles were found to be represented in this population. The polymorphism of B27 alleles found in a sample of the population from the Azores is higher than the Caucasian groups described. B*2703 and B*2707 have not previously been described to be represented in Caucasians and this could indicate admixtures with different populations of the world. In addition, the B*2708 allele was found to be associated with AS in a large family from the Azores. This association has not been previously reported in either ethnic group and needs to be confirmed in other population studies. This is of considerable interest since has only been described as a rare subtype underrepresented in the British population and has not been previously found to be associated with AS. B*2708 carries the sequence specifying the Bw6 epitope in contrast to most B27 alleles which carry a Bw4 sequence. Differences in this region (residues 77-83) can alter the F-pocket and affect T-cell recognition. The importance that these molecular changes can play in the pathogenesis of AS is discussed.

Azores↗

PubMed1999

Glucocorticoids ablate IL-1beta-induced beta-adrenergic hyporesponsiveness in human airway smooth muscle cells.

We have previously reported that interleukin (IL)-1beta decreases responsiveness of cultured human airway smooth muscle (HASM) cells to beta-agonists. The purpose of this study was to determine whether glucocorticoids inhibit this IL-1beta effect. Dexamethasone (Dex; 10(-6) M) had no effect on concentration-related decreases in cell stiffness in response to isoproterenol (Iso) in control cells as measured by magnetic twisting cytometry but prevented the decreased responsiveness to Iso observed in IL-1beta (20 ng/ml)-treated cells. In addition, Dex had no effect on Iso-stimulated cAMP formation in control cells but prevented the IL-1beta-induced reduction in Iso-stimulated cAMP formation. Similar effects on cell stiffness and cAMP responses were seen after pretreatment with the glucocorticoid fluticasone proprionate (FP). Dex and FP also prevented IL-1beta-induced hyporesponsiveness to PGE(2) stimulation. In contrast, neither IL-1beta nor glucocorticoids had any effect on cell stiffness responses to dibutyryl cAMP. We have previously reported that the IL-1beta effect on beta-adrenergic responsiveness is mediated through cyclooxygenase-2 expression and prostanoid formation. Consistent with these observations, IL-1beta-induced cyclooxygenase-2 expression was virtually abolished by FP at concentrations of 10(-10) M and greater, with a resultant decrease in PGE(2) formation. However, Dex did not inhibit IL-1beta-induced nuclear translocation of nuclear factor-kappaB or activator protein-1 in HASM cells. In summary, our results indicate that, in HASM cells, glucocorticoids alone do not alter responses to beta-agonists but do inhibit IL-1beta-induced beta-adrenergic hyporesponsiveness. Glucocorticoids mediate this effect by inhibiting prostanoid formation but without altering nuclear factor-kappaB or activator protein-1 translocation.

Bronchodilator Agents↗

PubMed1999

Lectin-like protein fractions in lactic acid bacteria isolated from chickens.

Agglutination of fifty bacterial strains isolated from gastric-intestinal tract of chickens with yeasts treated with glutaraldehyde and glycine was assayed to study possible adhesion mechanisms to epithelia. It was found that Lactobacillus fermentum, Lactobacillus fermentum subsp. cellobiosus and Lactobacillus animalis agglutinated yeasts massively and this agglutination was inhibited in each strain by different representative sugars: agglutination was inhibited in three selected strains with 0.2 M mannose. The three strains agglutinated chicken red blood cells, but did not agglutinate human red blood cells, whereas the agglutinating capacity for other animal erythrocytes was variable. The lectins were partially purified on a Sephadex G-75 column and affinity chromatography. The molecular weight of each of the protein subunits was estimated as about 50-67 kDa using electrophoretic techniques. After treatment with lipase and metaperiodate modifications bacterial superficies and/or liberation of some structures produced an unspecific interaction with increase in the yeast agglutination and hemagglutination. The optimal conditions of work were: pH 6-7, Ca2+ 1 mM, Mg2+ 2 mM and 37-42 degrees C.

Agglutination↗

PubMed1999

Chronic photodamage in skin of mast cell-deficient mice.

Solar elastosis is a hallmark of photoaged human skin and a prominent feature in experimentally produced photoaging in murine skin. The products of mast cells have been implicated in the development of photoaged skin. We evaluated whether products from mast cells mediate chronic UVB-induced changes in murine skin by employing a strain of mast cell-deficient mice, WWv. The responses in these mice were compared to those in BALB/c, another albino mouse strain. Mice were exposed three times per week to UVB radiation for 11 weeks; the total dose was 18.8 J/cm2. Irradiated WWv mice showed greater epidermal alterations than the irradiated BALB/c mice. In the dermis, a 3.6-fold increase in elastin content, as measured by desmosine, was produced in the UVB-treated BALB/c mice; in contrast, no difference was observed in elastin between UVB-treated and untreated WWv mice. Collagen content was not increased by UVB treatment in either strain, and the glycosaminoglycan content increased a similar amount in UVB-treated mice in both strains. The number of mast cells increased two-fold and the number of neutrophils increased six-fold in UVB-treated BALB/c mice compared to age-matched unirradiated controls. Neutrophils, as well as mast cells, were absent in untreated and UVB-treated WWv mouse skin. These results suggest that products of mast cells are important in the development of solar elastosis in murine skin either by directly inducing elastin production by fibroblasts or indirectly by mediating the presence of other cell types that produce products that increase fibroblast elastin production.

Animals↗

PubMed1999

Mixed gonadal dysgenesis: a syndrome of broad clinical, cytogenetic and histopathologic spectrum.

Mixed gonadal dysgenesis (MGD) is an abnormality of sexual differentiation (ASD), which encompasses an heterogeneous group of different gonadal and phenotypic abnormalities. This study describes the main clinical features found in 16 patients with MGD, relating the clinical presentation with cytogenetic evaluation and histopathological findings. For purpose of this study, MGD was considered in those patients who fulfilled the following diagnostic criteria: 1) müllerian and/or wolfflan derivatives; 2) any of the following gonadal characteristics: a) bilateral intrabdominal or scrotal immature testicular tissue; b) intrabdominal or scrotal immature testicular tissue with contralateral streak gonad. Patients were selected from an ASD study which was carried out in Medical Genetic Unit of University of Zulia (UGM-LUZ), Maracaibo, Venezuela, from 1980 to 1997. The following information was extracted from the medical history at UGM-LUZ: age, gender which patient was reared, clinical presentation, cytogenetic evaluation, laparoscopic findings and gonadal biopsy. Sixteen patients fulfilled the diagnostic criteria and ranged in age from 1.2 to 39.4 years with an average of 12.65 years. Only 5 patients were reared as males. Twelve patients consulted for genital ambiguity. Chromosomal evaluation was as following: 8 patients with 45,X/46,XY mosaicism: 5 had a 46,XY normal male karyotype and the remaining patients: 46,XX; 46,XX/46,XY and 45,X/46,Xi(Xq) karyotypes, respectively. All patients showed müllerian derivatives and occasionally wolffian derivatives. Gonadal tumors were present in 2 patients. Molecular studies of genes that govern gonadal development are necessary for a better understanding of the wide heterogeneity present in MGD.

Adolescent↗

PubMed1998

Study of the morphology of the cell walls of some strains of lactic acid bacteria and related species.

The objective of the present study was to find an explanation for the biological effect of the bacteria present in a biotherapeutic milk (Lactobacillus casei CRL 431 and Lactobacillus acidophilus CRL 730). The ability of bacterial cell walls to induce an immune response when introduced into an organism is well known. In this paper we specifically analyzed the morphology of these cell walls. Besides the two bacterial strains used in the fermented milk, two other lactic acid bacteria, belonging to another genus and unable to induce an immune system response, as well as a strain of Propionibacterium, of which the immune modulating capacity is known, were used in this work. We found a structural particularly in strains with immunostimulating capacity (L. casei CRL 431 and P. acidopropionici CRL 1198): molecules which protrude from the cell surface. In L. casei CRL 431 these molecules were identified as lectins because they are able to agglutinate yeast cells treated with glutaraldehyde and glycine. The structures protruding from P. acidipropionici CRL 1198 cells were teichoic acids. Teichoic acid and lectin-like structures can participate in adhesion to intestinal cells. The immunostimulation observed can be induced by the adhesion phenomenon.

Adjuvants, Immunologic↗

PubMed1998

[Ameloblastic fibro-odontoma. Clinical aspects and review of the literature].

Ameloblastic fibro-odontoma is a rare odontogenic tumor. It is formed by proliferation of epithelial odontogenic elements combined with ectomesechimal tissue. The presence of dentine, enamel and osteoid like tissue can be identified. Cases of sarcomatous degeneration have been described. In this work, we present two new cases of ameloblastic fibro-odontoma, analyzing the most important aspects of their differential diagnosis, with a review of literature.

Adult↗

PubMed1998

The placental blood program of the Barcelona Cord Blood Bank.

Cord blood has recently become an alternative to bone marrow transplantation, generating the need for cord blood banks where large numbers of frozen cord blood units can be stored. The Barcelona Cord Blood Bank (bcB) was created in October 1995. Initially, several methods for volume reduction were tested, including Ficoll, Percoll, Gelatin and HES sedimentation. Of these, HES sedimentation (88% +/- 11 CD34+ cells recovery) was the one chosen for routine banking. Up to November 1997, the bank has processed 754 units with a median of 1.05 x 10(9) nucleated cells and 2.5 x 10(6) CD34+ cells stored per unit. Nine of these units have been shipped for transplantation.

Adult↗

PubMed1997

Dietary factors in relation to weight change among men and women from two southeastern New England communities.

OBJECTIVE: Dietary factors, independent of total energy, may be important in promoting obesity. We examined prospectively the relationship between baseline diet composition and weight gain among adult men and women from southeastern New England. DESIGN: The prospective association of nutrient consumption and weight change was examined in a randomly selected cohort examined four years apart. SUBJECTS: Adults aged 18 through 64 years from two communities in Southeastern New England were randomly selected for the study after being interviewed in their homes. The present investigation is based on a subgroup of 465 individuals who completed a food-frequency questionnaire in 1986 or 1987 and were reinterviewed four years later. STATISTICAL ANALYSES: Multiple regression analyses were used to determine the association of weight change with different nutrients and food groups after adjusting for age, smoking status, baseline body mass index, physical activity level, and total energy. RESULTS: Total energy was positively associated with weight gain and age was inversely associated with weight gain. None of the nutrients or food groups were significantly related to weight gain. CONCLUSIONS: These findings indicate that weight gain increased with increasing baseline total energy intake, particularly in the young. Future research is required to determine ways of decreasing energy intake in younger individuals.

Adult↗

PubMed1997

HLA-B27 polymorphism and worldwide susceptibility to ankylosing spondylitis.

HLA-B27 is strongly associated to ankylosing spondylitis (AS) and represents a family of eleven B27 alleles (B*2701-11). Our aim was to analyze the distribution of B27 subtypes by PCR/SSOP and genomic sequencing in a large group of populations (n = 17). 711 B27-positive samples from Caucasoid, Asian, African, Amerindian and Polynesian populations were selected to ascertain transracial gene mapping of the B27 subtypes. 476 of these were AS patients, chosen to investigate the contribution of B27 alleles to AS susceptibility. Some significant new findings have arisen from this study: 1) B*2705 was the predominant subtype in circumpolar and subarctic areas. B*2702 was found to be practically restricted to Caucasian populations, showing a higher frequency in Middle-East (Jews) and North Africa (Arabs/Berbers) groups. 2) B*2703 appears associated with AS in Western Africans. This is of remarkable interest since it was suggested that B*2703 would be negatively disease-associated. 3) Although B*2706 appears negatively associated with AS in Thais, we identified two patients from northern China carrying it. This may be a reflection of a disease heterogeneity and could indicate that more than one pathogenic agent can be involved in AS. B*2709 has been recently described as negatively associated with AS in Sardinians. The molecular changes His114Asp (B*2706) and Asp116His (B*2709) could modify the genetic susceptibility to AS.

Alleles↗

PubMed1997

Complete androgen insensitivity syndrome: clinical and anatomopathological findings in 23 patients.

Complete Androgen Insensitivity Syndrome (CAIS) is a type of Male Pseudohermaphroditism due to a defect in the androgen receptor which is a DNA-binding, transcription-regulating protein whose properties are induced on androgen binding. This defect is caused by mutations of a gene localized in Xq11-12. The objective of this study is the description of the clinical and pathological features of patients with female phenotype, karyotype 46, XY and diagnosis of CAIS. They were referred to Medical Genetic Unit of University of Zulia, Maracaibo, Venezuela, between 1971-1995. The diagnostic criteria and clinical and pathological findings are reviewed. Twenty-three patients fulfilled the diagnostic criteria. Most of patients were 13 years old or older (postpuberal). The main reasons for consultation were: primary amenorrhea, inguinal hernia, familial history of CAIS and fusion of labia minora. Seventeen patients from 5 families were diagnosed with CAIS and only one per family in 6 families. All patients showed a female general phenotype with unambiguously female external genitalia. Gonadal localization (right/left) was as follows: abdominal/abdominal: 65%; abdominal/inguinal: 26%; inguinal/abdominal: 9%. Histologic features of gonads were similar to those in cryptorchid testes of otherwise normal males. There was no evidence of development of gonadal neoplasia. The patients reported here provide a remarkable opportunity to study the molecular genetic characterization that can serve as a primary tool for diagnosis and subsequent therapy.

Adolescent↗

PubMed1996

In vivo phosphorylation of type II myosin in Saccharomyces cerevisiae.

Phosphorylation of the myosin heavy chain has been shown to be a key regulatory mechanism of several non-muscle myosins. In this study we present evidence demonstrating that the yeast type II myosin heavy chain is phosphorylated in vivo. Phosphorylation of serine residues was confirmed by direct metabolic labeling with [32P] and by indirect immunostaining of phosphoserine with a specific monoclonal antibody. Loss of immunoreactivity in a targeted deletion of the 26 amino acid carboxyl terminal segment of the type II myosin heavy chain suggests that the phosphorylation occurs at one or more serine residues located between residues 1903 and 1928.

Amino Acid Sequence↗

PubMed1996

Dexamethasone up-regulates mRNA for Na+,K(+)-ATPase in some spinal cord neurones after cord transection.

We have studied the effects of spinal cord transection and of dexamethasone (DEX) treatment on mRNA biosynthesis of the Na+, K(+)-ATPase, a key enzyme necessary for neurotransmission, membrane repolarization and nutrient uptake in the CNS. In situ hybridization analysis revealed a significant reduction in mRNA for the alpha 3 catalytic subunit of the enzyme in medium and large size ventral horn neurones (1000-2300 microns2) but not in small cells (1000 microns2) 24 h after spinal cord transection. DEX treatment significantly reversed the transection effect in medium and large size neurones. It is suggested that up-regulation of mRNA expression for Na+,K(+)-ATPase may constitute an important mechanism by which glucocorticoids help to re-establish neuronal function after spinal cord injury.

Animals↗

PubMed1996

Fibrates induce mdr2 gene expression and biliary phospholipid secretion in the mouse.

Disruption of the murine mdr2 gene leads to the complete absence of biliary phospholipids. We tested the hypothesis that the increase in biliary phospholipid output induced by fibrates is mediated via induction of the hepatic mdr2 gene and its encoded product, the P-glucoprotein canalicular flippase. Increased levels of mdr2 mRNA were observed in the liver of mice treated with different fibrates: ciprofibrate, 660+/-155% (as compared with control group); clofibrate, 611+/-77%; bezafibrate, 410+/-47%; fenofibrate, 310+/-52%; gemfibrozil, 190+/-25% (P <0.05 compared with control group). Induction of expression of the mdr gene family was specific to the mdr2 gene. Two- to three-fold increases in P-glycoprotein immunodetection were evident on the canalicular plasma-membrane domain of clofibrate- and ciprofibrate-treated mice. Biliary phospholipid output increased from 4.2+/-1.2 nmol/min per g of liver in the control group to 8.5+/-0.6, 7.1+/-2.9 and 5.8+/-2.5 in ciprofibrate-, clofibrate- and bezafibrate-treated mice respectively (P <0.05 compared with control group). Moreover, a significant correlation between biliary phospholipid output and the relative levels of mdr2 mRNA was found (r=0.86; P <0.05). In treated animals, bile flow as well as cholesterol and bile acid outputs remained unchanged. Our findings constitute the first evidence that pharmacological modulation of biliary lipid secretion mediated by fibrates can be related to the overexpression of a specific liver gene product, the mdr2 P-glycoprotein, and are consistent with the hypothesis that the mdr2 P-glycoprotein isoform plays a crucial role in the secretion of biliary phospholipid.

ATP Binding Cassette Transporter, Subfamily B, Mem↗

PubMed1996

Characterization of interleukin-8 receptors in non-human primates.

Interleukin-8 is a chemokine with a potent neutrophil chemoattractant activity. In humans, two different cDNAs encoding human IL8 receptors designated IL8RA and IL8RB have been cloned. IL8RA binds IL8, while IL8RB binds IL8 as well as other alpha-chemokines. Both human IL8Rs are encoded by two genes physically linked on chromosome 2. The IL8RA and IL8RB genes have open reading frames (ORF) lacking introns. By direct sequencing of the polymerase chain reaction products, we sequenced the IL8R genes of cell lines from four non-human primates: chimpanzee, gorilla, orangutan, and macaca. The IL8RB encodes an ORF in the four non-human primates, showing 95% - 99% similarity to the human IL8RB sequence. The IL8RA homologue in gorilla and chimpanzee consisted of two ORF 98% - 99% identical to the human sequence. The macaca and orangutan IL8RA homologues are pseudogenes: a 2 base pair insertion generated a sequence with several stop codons. In addition, we describe the physical linkage of these genes in the four non-human primates and discuss the evolutionary implications of these findings.

Amino Acid Sequence↗

PubMed1996

Self-reported alcohol intake using two different question formats in southeastern New England.

BACKGROUND: Quantitative measures of alcohol intake are not always available in population studies. METHOD: The authors evaluated whether a question on alcohol intake embedded within a general health survey could be used as a surrogate marker for alcohol intake. We compared alcohol intake assessed with a food frequency questionnaire (FFQ) with alcohol intake assessed with a simple dichotomous survey question in a population-based sample. RESULTS: The study population consisted of 755 men and 1164 women from two communities in southeastern New England in the USA. There was strong agreement between the two alcohol questions for the classification of nondrinkers (98.1%). When participants were classified according to the quantity of alcohol consumed on the FFQ, the ability of the simple question to identify drinkers improved in a dose-response fashion. The Kappa statistic was 0.08 (P < 0.001), 0.38 (P < 0.001), and 0.81 (P < 0.001) for low, medium, and high consumers of alcohol, respectively. CONCLUSIONS: These results suggest that the survey alcohol question provides a useful qualitative measure of categorizing nondrinkers and identifying drinkers who consume more than one drink per day. In population studies where quantitative measures of alcohol intake may not be available a survey alcohol question may prove useful when alcohol intake is likely to confound results, and adjustment of the data is needed.

Adult↗

PubMed1996

Development of cutaneous tolerance to ultraviolet B during ultraviolet B phototherapy for psoriasis.

During a schedule of multiple exposures to ultraviolet B radiation (UVB, 280-320 nm), skin develops a reduced sensitivity, variously called tolerance, photoadaptation, accommodation or acclimatization. In this study we have investigated the development of tolerance in the normal skin of a group of psoriatic patients during the course of UVB therapy. Tolerance was assessed by phototests carried out on non-lesional skin as frequently as possible throughout the treatment. Maximum tolerance was developed by the group of individuals most sensitive to UVB, which was twice that of the least sensitive group. The minimal perceptible erythema dose (MPE) increased rapidly in the first 2 weeks (220% per week) and reached a plateau by the eighth week of 800% above the baseline MPE dose. For the more sensitive patients there was a further increase in sensitivity (decrease in MPE dose) after the ninth week of continuous treatment. Tolerance to UVB also involves pigmentation in the first few weeks, but in these patients there was no evidence of hyperpigmentation by the end of treatment. While epidermal hyperplasia is most likely to play a leading role in the development of tolerance to UV, there is no reason to expect this protection to decrease under conditions of continuous exposure. Thus, accommodation to ultraviolet radiation (UVR) is not a monotonically increasing process but appears to alter the accepted reactions of human skin to UVR.

Humans↗