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Biomedical subjects

G Ayala

Publications and source records attributed to G Ayala.

At least 37 records · Page 2Linked to original sources
PubMed2000

TLA-1: a new plasmid-mediated extended-spectrum beta-lactamase from Escherichia coli.

Escherichia coli R170, isolated from the urine of an infected patient, was resistant to expanded-spectrum cephalosporins, aztreonam, ciprofloxacin, and ofloxacin but was susceptible to amikacin, cefotetan, and imipenem. This particular strain contained three different plasmids that encoded two beta-lactamases with pIs of 7.0 and 9.0. Resistance to cefotaxime, ceftazidime, aztreonam, trimethoprim, and sulfamethoxazole was transferred by conjugation from E. coli R170 to E. coli J53-2. The transferred plasmid, RZA92, which encoded a single beta-lactamase, was 150 kb in length. The cefotaxime resistance gene that encodes the TLA-1 beta-lactamase (pI 9.0) was cloned from the transconjugant by transformation to E. coli DH5alpha. Sequencing of the bla(TLA-1) gene revealed an open reading frame of 906 bp, which corresponded to 301 amino acid residues, including motifs common to class A beta-lactamases: (70)SXXK, (130)SDN, and (234)KTG. The amino acid sequence of TLA-1 shared 50% identity with the CME-1 chromosomal class A beta-lactamase from Chryseobacterium (Flavobacterium) meningosepticum; 48.8% identity with the VEB-1 class A beta-lactamase from E. coli; 40 to 42% identity with CblA of Bacteroides uniformis, PER-1 of Pseudomonas aeruginosa, and PER-2 of Salmonella typhimurium; and 39% identity with CepA of Bacteroides fragilis. The partially purified TLA-1 beta-lactamase had a molecular mass of 31.4 kDa and a pI of 9.0 and preferentially hydrolyzed cephaloridine, cefotaxime, cephalothin, benzylpenicillin, and ceftazidime. The enzyme was markedly inhibited by sulbactam, tazobactam, and clavulanic acid. TLA-1 is a new extended-spectrum beta-lactamase of Ambler class A.

Amino Acid Sequence↗
PubMed2000

Immunological diagnosis of human hydatid cyst relapse: utility of the enzyme-linked immunoelectrotransfer blot and discriminant analysis.

A discriminant technique was applied to the different serological patterns obtained by enzyme-linked immunoelectrotransfer blotting (EITB) and by conventional immunological tests, in order to differentiate the residual antibody patterns present in healed hydatidosis from the ones present in patients with active hydatidosis. For this purpose, specific antibodies against Echinococcus granulosus were detected by indirect hemagglutination, agglutination of latex particles, basophil degranulation, and EITB for 23 patients with active hydatidosis and 45 patients with surgically cured hydatidosis. Discriminant analysis of the different serological patterns obtained by EITB and conventional serology correctly classified 92.54% of patients (93.3% if the patients are differentiated according to the time elapsed since surgery). This method detected the presence of active hydatidosis in 95.6% of patients for whom abdominal ultrasonography had confirmed the presence of active hydatid cysts. The global specificity was 88.9%. The specificity was 97.1% for patients who had been operated on 3 years ago or more and 63.6% for patients with less time since surgery.

Animals↗
PubMed1999

Single-step PCR amplification and enzyme restriction analysis of the entire Helicobacter pylori cytotoxin vacA gene for genetic variability studies.

To monitor changes along the entire Helicobacter pylori vac A gene we carried out full-length single-step PCR amplification in 21 gastritis and gastric cancer isolates. HindIII restriction analysis led us to detect a > 400-bp internal insertion in vacA subsequently shown to be a direct 451-bp gene duplication. We found HindIII profiles for 16 genes that allowed their grouping into two restriction patterns that were related to theoretical profiles for previously sequenced Western genes. Comparisons with theoretical HindIII patterns for Japanese isolates appear suggestive of geographical H. pylori clonality. Full-length single-step PCR amplification seems suitable for quick restriction pattern assignment and detection of gene size changes.

Bacterial Proteins↗
PubMed1999

Inhibition and uncoupling of oxidative phosphorylation by nonsteroidal anti-inflammatory drugs: study in mitochondria, submitochondrial particles, cells, and whole heart.

The effects of the anti-inflammatory drugs diclofenac, piroxicam, indomethacin, naproxen, nabumetone, nimesulide, and meloxicam on mitochondrial respiration, ATP synthesis, and membrane potential were determined. Except for nabumetone and naproxen, the other drugs stimulated basal and uncoupled respiration, inhibited ATP synthesis, and collapsed membrane potential in mitochondria incubated in the presence of either glutamate + malate or succinate. Plots of membrane potential versus ATP synthesis (or respiration) showed proportional variations in both parameters, induced by different concentrations of nimesulide, meloxicam, piroxicam, or indomethacin, but not by diclofenac. The activity of the adenine nucleotide translocase was blocked by diclofenac and nimesulide; diclofenac also slightly inhibited mitochondrial ATPase activity. Naproxen did not affect any of the mitochondrial parameters measured. Nabumetone inhibited respiration, ATP synthesis, and membrane potential in the presence of glutamate + malate, but not with succinate. NADH oxidation in submitochondrial particles also was inhibited by nabumetone. Nabumetone inhibited O2 uptake in intact cells and in whole heart, whereas the other five drugs stimulated respiration. These observations revealed that in situ mitochondria are an accessible target. Except for diclofenac, a negative inotropic effect on cardiac contractility was induced by the drugs. The data indicated that nimesulide, meloxicam, piroxicam, and indomethacin behaved as mitochondrial uncouplers, whereas nabumetone exerted a specific inhibition of site 1 of the respiratory chain. Diclofenac was an uncoupler too, but it also affected the adenine nucleotide translocase and the H+-ATPase.

Adenosine Triphosphate↗
PubMed1999

Effect of anticardiolipin antibodies on prolactin and insulin-like growth factor binding protein-1 production by human decidual cells.

PROBLEM: The effect of anticardiolipin antibodies (ACAs) on basal- and growth factor-stimulated prolactin and insulin-like growth factor (IGF) binding protein (BP)-1 production by cultured human decidual cells was investigated. METHOD OF THE STUDY: Decidual cells were cultured for 24, 48, or 96 hr in medium supplemented with 5% ACA-containing or 5% control serum and increasing concentrations of insulin (1-10 micrograms/mL) or IGF-1 (10-100 ng/mL). RESULTS: No significant increase in prolactin production was observed after addition of increasing doses of insulin and IGF-I in the presence of ACA-containing serum, while a dose-dependent stimulation was seen with control serum. Time-dependent prolactin accumulation was also reduced when cells were cultured in the former conditions. IGF BP-1 release was not affected by insulin and IGF-I in the presence of both sera. However, lower IGF BP-1 levels and a less pronounced time-dependent accumulation were observed in the presence of ACA-positive serum. CONCLUSIONS: Our data suggest that ACAs affect cellular transduction mechanisms regulating critical events, such as decidual cell differentiation. These cellular dysfunctions might be relevant in the induction of some obstetric disorders typical of this syndrome.

Antibodies, Anticardiolipin↗
PubMed1999

Immunological diagnosis of human cystic echinococcosis: utility of discriminant analysis applied to the enzyme-linked immunoelectrotransfer blot.

An enzyme-linked immunoelectrotransfer blot for the diagnosis of human hydatid disease was performed, and the different antibody responses were analyzed by a discriminant analysis. This multivariate technique gave us, first, a selection of the most important responses against Echinococcus granulosus infection and, second, a procedure for the classification of patients into two groups: patients with hydatid disease and patients without a history of hydatid disease. This method was applied to 67 patients, 25 with active hydatid cysts (24 hepatic and 1 pulmonary) and 42 without a history of hydatid disease and was compared with the results obtained by conventional serology: indirect hemagglutination, latex particle agglutination, and basophil degranulation. An immunoelectrotransfer blot coupled to a discriminant analysis was more sensitive than conventional serological diagnosis and detected 100% of patients with an active hepatic hydatid cyst with a specificity of 100%. This method, however, failed to detect an uncomplicated hyaline pulmonary hydatid cyst.

Discriminant Analysis↗
PubMed1998

Porcine cartilage transplants in the cynomolgus monkey. III. Transplantation of alpha-galactosidase-treated porcine cartilage.

BACKGROUND: Studies on transplantation of porcine meniscus and articular cartilage into monkeys are important for evaluating the possible use of such tissues in humans. In addition, such studies shed light on the chronic xenograft rejection process in primates. Transplantation of porcine cartilage into cynomolgus monkeys for 2 months results in a many-fold increase in anti-Gal activity and in a strong cellular inflammatory response of T lymphocytes and macrophages within the implants. The objective of this study was to determine whether elimination of Galalpha1-3Galbeta1-4GlcNAc-R (alpha-gal epitopes) from the xenograft may alter the immune response and the inflammatory reaction. METHODS: Porcine meniscus and articular cartilage specimens were treated with recombinant alpha-galactosidase (100 U/ml), and the absence of alpha-gal epitopes was assessed by the binding of the monoclonal anti-Gal antibody M86. The treated cartilage specimens were transplanted into the suprapatellar pouch of cynomolgus monkeys. The immune response to cartilage was monitored in the serum and the inflammatory reaction was assessed in the xenografts, which were explanted after 2 months. RESULTS: Incubation with alpha-galactosidase resulted in complete removal of alpha-gal epitopes from the cartilage. The increase in anti-Gal activity in the transplanted monkeys was marginal. However, most monkeys produced antibodies to antigens specific to porcine cartilage. The inflammatory response within the alpha-galactosidase-treated xenografts was much lower than in nontreated cartilage and the proportion of T lymphocytes within the cellular infiltrates was greatly reduced. CONCLUSIONS: Treatment of cartilage xenografts with alpha-galactosidase successfully removes alpha-gal epitopes from porcine cartilage. Transplantation of the treated cartilage results in the production of only anti-porcine cartilage-specific antibodies and a reduced inflammatory response consisting primarily of macrophages infiltrating into the cartilage.

Animals↗
PubMed1998

Macular edema computer-aided evaluation in ocular vein occlusions.

This paper is concerned with the use of digital fundus imaging to detect, quantify, and follow up macular angiographic leakage due to retinal vein occlusions. Images were matched automatically. We detected those pixels with a high increment in gray level within the closest area to the foveal center. Binary images displaying leakage were obtained. The procedure was checked against two observers' agreement. Twenty-one angiographic studies were collected. Two images of each sequence were selected for digitalization. Numerical descriptors of the leakage were proposed and quantification plots were designed for each pair of images. Interobserver concordance ranged between 82 and 98% when manually detected leakage was compared with computer segmented areas. The detection and quantification of leakage areas may serve as a guide for severity evaluation and treatment planning. Moreover, they permit a precise follow-up of macular edema.

Adult↗
PubMed1998

Basaloid squamous cell carcinoma: a distinctive human papilloma virus-related penile neoplasm: a report of 20 cases.

Most penile neoplasms are squamous cell carcinomas (SCC), but there are subtypes that show morphologic and possibly etiologic differences. Clinicopathologic features of 20 patients with basaloid carcinoma (BC), an unusual variant of squamous cell carcinoma, are presented. Median age was 52 years, and all tumors were located in the glans, three confined to the perimeatal region. Average tumor size was 3.8 cm. Microscopically, nests of small, basophilic cells with numerous mitosis were present. Human papillomavirus DNA sequences (type 16), using the polymerase chain reaction (PCR), were found in 9 of 11 cases. Differential diagnosis included urethral transitional cell, basal cell, small cell neuroendocrine, and metastatic carcinoma. Factors more significantly associated with regional metastasis and mortality were tumor thickness greater than 10 mm and infiltration of the corpus cavernosum. A comparison with typical squamous cell carcinoma showed basaloid carcinoma to have a higher histologic grade, a deeper invasion of penile anatomic levels, and a higher mortality rate. Of 17 patients observed, 10 were dead of disease (average time, 34 months), one was alive with disease 6 months after diagnosis, and 5 were alive and free of disease (average time, 71 months); the remaining patient died of other causes. Basaloid carcinoma is a distinctive morphologic subtype of squamous cell carcinoma frequently associated with the human papilloma virus.

Adult↗
PubMed1998

Endothelin-1: expression and role in human corpus luteum.

PROBLEM: Several recent data suggest an involvement of endothelin (ET)-1, a powerful vasoconstrictor peptide, in reproductive function. This study was designed to investigate the presence and role of ET-1 in human corpus luteum. METHOD OF STUDY: Purified luteal cells were incubated for different times with ET-1 or ET-3 alone or associated with human chorionic gonadotropin. In another set of experiments cells were treated with ET-1 and BQ485, an ET-A receptor antagonist, or with phorbol 12-myristate-13 acetate (PMA), an activator of protein kinase C. RESULTS: ET-1 reduced both basal and human chorionic gonadotropin-induced progesterone production at all examined times, similarly PMA inhibited basal progesterone synthesis. BQ485 prevented the inhibitory effect of ET-1, while no effect was observed with ET-3. Finally, ET-1 mRNA was detected in the luteal cells. CONCLUSION: ET-1 is expressed by human luteal cells and reduces basal and human chorionic gonadotropin-induced progesterone synthesis through the ET-A receptors and the protein kinase C pathway. Conversely, ET-3 does not affect luteal steroidogenesis.

Adult↗
PubMed1994

NK1 receptor expression by cholinergic interneurones in human striatum.

Neurokinin-1 (NK1) receptor expression in human striatum was analysed using the polymerase chain reaction. To determine whether cholinergic interneurones express this receptor, in situ hybridization histochemistry was then applied to caudate nucleus and putamen. Radioactive oligonucleotide probes specific for choline acetyltransferase (ChAT) and NK1 receptor mRNA were used on adjacent cryostat sections. All of the 160 identified neurones positive for ChAT were also labelled for NK1 receptor. Moreover, in the caudate nucleus, NK1 receptor mRNA was detected in a population of large neurones that were not cholinergic. These results are consistent with the hypothesis that NK1 receptor-mediated mechanisms are involved in the function of cholinergic interneurones. This might be relevant to pharmacological or pathophysiological situations where substance P inputs are modified.

Aged↗
PubMed1993

Inhibition of an in vivo antigen-specific IgE response by antibodies to CD23.

Immunoglobulin E (IgE) mediates many allergic responses. CD23 is a 45-kilodalton type II transmembrane glycoprotein expressed in many cell types. It is a low-affinity IgE receptor and interacts specifically with CD21, thereby modulating IgE production by B lymphocytes in vitro. In an in vivo model of an allergen-specific IgE response, administration of a rabbit polyclonal antibody to recombinant human truncated CD23 resulted in up to 90 percent inhibition of ovalbumin-specific IgE synthesis. Both Fabs and intact IgG inhibited IgE production in vitro and in vivo. Thus, CD23 participates in the regulation of IgE synthesis in vivo and so could be important in allergic disease.

Amino Acid Sequence↗
PubMed1993

Inhibition of axonal growth by SNAP-25 antisense oligonucleotides in vitro and in vivo.

Axonal elongation and the transformation of growth cones to synaptic terminals are major steps of brain development and the molecular mechanisms involved form the basis of the correct wiring of the nervous system. The same mechanisms may also contribute to the remodelling of nerve terminals that occurs in the adult brain, as a morphological substrate to memory and learning. We have investigated the function of the nerve terminal protein SNAP-25 (ref. 2) during development. We report here that SNAP-25 is expressed in axonal growth cones during late stages of elongation and that selective inhibition of SNAP-25 expression prevents neurite elongation by rat cortical neurons and PC-12 cells in vitro and by amacrine cells of the developing chick retina in vivo. These results demonstrate that SNAP-25 plays a key role in axonal growth. They also suggest that high levels of SNAP-25 expression in specific areas of the adult brain may contribute to nerve terminal plasticity.

Animals↗