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M Suárez

Publications and source records attributed to M Suárez.

At least 55 records · Page 3Linked to original sources
PubMed1997

Genomic polymorphism in herpes simplex virus keratitis.

Viruses are the major infectious agents causing conjunctivitis and keratoconjunctivitis. Two antigenic types, herpes simplex virus type 1 (HSV-1) and type 2 (HSV-2), can be recognized in which numerous genomic variants or genotypes have been described. HSV-1 infection is one of the major causes of blindness. Different strains can induce different types of ocular lesions. Twelve patients with acute herpetic epithelial keratitis were studied by monoclonal antibodies and restriction enzymes, and nine different HSV-1 genomic variants were identified. This study confirms that a variety of HSV-1 strains is associated to this kind of infection.

Herpesvirus 1, Human↗
PubMed1997

[Herpetic keratitis: clinical-virological correlation].

BACKGROUND: Herpetic keratitis is the main infectious cause of corneal opacity. The existence of effective antiviral agents underscores the need of an early diagnosis. AIM: To correlate clinical features of herpetic keratitis with virological studies. PATIENTS AND METHODS: Forty one patients with a clinical diagnosis of herpetic keratitis were studied. Viral isolation, polymerase chain reaction (PCR) and typification were done in a sample taken by swabbing the ocular lesion. RESULTS: Twenty six patients (31% female) had epithelial keratitis, that was mild or moderate in 88% of cases and acute in 77% of them. In 20 patients (77%), viral isolation and PCR were positive (HSV-2 in one case). Fifteen patients (67% female) had stromal keratitis, 93% of cases were moderate or severe and 53% were acute. Viral isolation was negative in all cases and in 20% PCR was positive. CONCLUSIONS: Viral isolation and PCR were equally sensitive in epithelial keratitis, but in stromal keratitis only PCR could detect the virus. Moderate acute dendrite was the predominant clinical manifestation. The higher proportion of women with stromal keratitis supports its possibly autoimmune etiology. HSV-2 is seldomly isolated and possibly associated to vertical transmission.

Acute Disease↗
PubMed1996

Purification and biochemical characterization of gentisate 1,2-dioxygenase from Klebsiella pneumoniae M5a1.

Gentisate 1,2-dioxygenase (E.C.1.14.13) was purified to homogeneity from Klebsiella pneumoniae M5a1, a soil bacterium able to degrade a great variety of aromatic compounds. The molecular mass of the purified holoenzyme was 159 kDa and its structure was deduced to be a tetramer with 38 kDa per subunit. Gentisate 1,2-dioxygenase appears to contain Fe2+ in its active site. The optimum temperature for enzyme activity was estimated to be 30 degrees C, the optimum pH values varied between 8 and 9 and the isoelectric point was 4.7. Gentisate dioxygenase exhibited typical saturation kinetics and had an apparent K(m) of 52 microM for gentisate. Its amino acid content was determined to be very similar to that of the enzyme from Pseudomonas acidovorans.

Amino Acids↗
PubMed1996

Cytogenetic and molecular analysis of the satellite DNA of the genus Ctenomys (Rodentia Octodontidae) from Uruguay.

The genus of subterranean rodents Ctenomys presents the widest range of variability in diploid number among mammals (from 2n = 10 to 2n = 70). In Uruguay, this variability is observed in karyotypes with 2n = 44, 50 or 58 and two geographically isolated populations with 70 chromosomes but different karyotypic structure. The last three populations were analyzed in the present study. They present a satellite DNA, which was isolated from genomic DNA after AluI digestion. In situ hybridization showed that this satellite DNA is located in the centromeric region of a few chromosomes, coincident with Hoechst 33258 staining and C-banding patterns. A similar satellite DNA was detected in Argentinian species of this genus. We established that, in spite of differences in number of positive heterochromatic blocks per karyotype, the C value is the same in the three populations studied. The nature and possible evolutionary path of this repeated DNA is discussed.

Animals↗
PubMed1996

[Forestry Law and the conservation of natural areas and wildlife].

The Forest Law of Ecuador consists of 107 articles, whereas its regulations contain 269 articles. They are related to forestry resources, forestry patrimony protection, forests and vegetation, forest production and benefits, the control and mobilization of the forestry resources, research and capacitation, and the forestry industry protection; to natural areas, wild flora and fauna, their patrimony, conservation, and economic support; and to the violation of the law and its judgment.

Animals↗
PubMed1996

Transcriptional activation of virulence genes in wild-type strains of Listeria monocytogenes in response to a change in the extracellular medium composition.

A panel of 103 Listeria monocytogenes strains of different origins was examined for haemolysin and lecithinase production in brain-heart infusion (BHI). Three distinct phenotypes were observed. Phenotype 1 was characterized by low to undetectable levels of expression and was exhibited by almost all strains tested. Phenotype 2 expressed high levels of haemolysin and lecithinase and was displayed by five strains: one (P14-A) was a spontaneous mutant derived from a type 1 isolate (P14); the four others (EGD-A, NCTC 7973, SLCC 2373 and CLIP 545) were all laboratory strains kept under in vitro conditions for a long period. Phenotype 3 was intermediate and was exhibited by another laboratory strain (L028). We therefore concluded that phenotype 1 corresponded to the wild type, whereas phenotypes 2 and 3 represented mutant or variant phenotypes. Interestingly, wild-type strains were able to dramatically increase the expression of virulence factors when cultured in BHI treated with activated charcoal (BHIC), up to levels similar to those constitutively expressed by the hyperhaemolytic/lecithinase variants in BHI. Experiments with P14 and P14-A demonstrated that both charcoal and the hyperhaemolytic/lecithinase mutation exerted their effect by inducing (or derepressing) transcription of prfA, the pleiotropic transcriptional activator of the L. monocytogenes virulence regulon. Moreover, P14 and P14-A were equally virulent for mice despite the different levels of virulence factor expression in BHI. Taken together, these observations indicate that L. monocytogenes turns off virulence gene expression when growing in vitro in a rich medium, and suggest that the increased levels of virulence factors in the hyperhaemolytic/lecithinase mutants and in wild-type strains grown in BHIC might represent the levels of expression needed in vivo by L. monocytogenes for infecting host tissues.

Animals↗
PubMed1996

Adrenocortical response to open-field test in rats with anterodorsal thalami nuclei lesion.

The influence of limbic anterodorsal thalami nuclei (ADTN) on adrenocortical activity and on emotional reactivity were investigated in male and female rats. The emotional reactivity was evaluated by means of the open-field test and the corticoadrenal function by means of plasma and adrenal corticosterone concentration. The results demonstrate that ADTN lesion does not affect the behavioural patterns in the open-field test on the 29th and 30th day after lesion nor adrenal response when animals are exposed to a novel situation.

Adrenal Cortex↗
PubMed1996

Changes in corticosterone levels and sperm functional activity by chronic stress in rats.

Corticosterone levels and epididymal sperm functional activity have been studied in rats subjected to immobilization stress (A: 12 days) or variable chronic stress (B: 24 days; C: 32 days and D: 32 days plus 28 days without stress). Plasma corticosterone levels were significantly enhanced in B and C groups. Body and testicular weight significantly decreased in C and D groups. A decrease in viability or percentage of progressive epididymal spermatozoa was detected in C and D groups. Responses of spermatozoa to hypoosmotic shock remained unaltered in all groups. Results suggest that sustained increase in activity of the hypothalamo-adenohypophyseal-adrenal cortical system alters the activity of the hypothalamo-adenohypophyseal-testicular axis.

Animals↗
PubMed1996

[Incidence of congenital cytomegalovirus infection in newborn infants of different socioeconomic strata].

Cytomegalovirus is the main agent of congenital viral infections. The aim of this study was to compare the incidence of congenital cytomegalovirus infections of two groups of newborns of differing socioeconomic status. Cytomegalovirus was isolated from urine or oropharingeal secretions in 218 children born in a private clinic and 471 born in a public hospital. Positive viral isolates were confirmed with indirect immunofluorescence using monoclonal antibodies. Infection was detected in 12 children (1.82%), four coming from the private clinic (1.86%) and 8 coming from the public hospital (1.81%). Ninety two percent of infected children were asymptomatic. Urine and oropharingeal secretion samples had the same yield for viral isolation. It is concluded that the incidence of congenital cytomegalovirus infection is similar to that described in developed countries.

Chile↗
PubMed1996

[Antigenic and genomic characterization of Herpes simplex virus isolated from double genital infections].

Two Herpes simplex viral serotypes, HSV type 1 and HSV type 2 may cause genital herpes. The aim of this study was to perform a genetical analysis and characterization of virus isolated from four patients with double genital herpetic infections. In eleven viral isolates, the cytopathic effect in Vero cells was studied, the antigenic type was determined using monoclonal antibodies and genomic analysis was performed with Eco RI, Hind III and Bgl II enzymes. Five viral isolates generated a diffuse and 6 a localized cytopathic effect. Monoclonal antibodies identified four HSV-1 and seven HSV-2. Genomic analysis had concordant results. Four HSV-1 were obtained, with different genomic patterns within them, three were different to the standard North American strain. The seven HSV-2 obtained had three different types of electrophoretic profiles, that were different to the standard North American strain. It is concluded that the genomic and antigenic analysis allowed the detection of herpetic genital infections caused by herpes virus type 1 and 2 in the same individual and the identification of herpes virus strains with distinct regional characteristics.

Antigens, Viral↗
PubMed1996

[Surveillance of St. Louis encephalitis, Eastern equine and Western equine in the province of Ciego de Avila].

Serological studies were carried out using the haemagglutination inhibition and neutralization tests so as to know the circulation dynamics of some arboviruses with the use of Western and Eastern equine encephalitis antigens and St Louis encephalitis antigens in human serum from sound and symptomatic individuals, as well as from sentinel birds, between 1987 and 1991, and during 1994. 1.7% of the asymptomatic subjects tested presented neutralizing antibodies to to Eastern equine and 4.8% to St Louis encephalitis. 16 patients with seroconversion by haemagglutination inhibition to St Louis virus were detected. Surveillance of sentinel birds showed that during 1988, 1989, and 1994. St. Louis circulated in the municipalities of Morón, Bolivia and Chambas; whereas in the latter the Eastern equine encephalitis circulated in 1988 and 1989. Antibodies to Western equine encephalitis were detected in sound individuals by haemagglutination inhibition due seemingly to heterologous antibodies, since there were no neutralizing antibodies against this virus.

Antibodies, Viral↗
PubMed1995

Purification and characterization of the 3-hydroxybenzoate-6-hydroxylase from Klebsiella pneumoniae.

We isolated 3-hydroxybenzoate-6-hydroxylase (E.C.1.14.13.), an inducible enzyme that catalyzed the para-hydroxylation of 3-hydroxybenzoate (3-HBA) to 2,5-dihydroxybenzoate, from Klebsiella pneumoniae. Although the enzyme was found to be mainly induced by its substrate, a coordinated induction of 3-hydroxybenzoate hydroxylase and gentisate dioxygenase was also observed in the presence of the product of the reaction. The purified enzyme was a monomer with a molecular mass of 42,000. It contained FAD as a prosthetic group, utilized NADH or NADPH with similar efficiencies and its activity was inhibited by Cu2+, Fe2+ and Hg2+. Other properties, such as induction mechanism and kinetic parameters were also studied. Moreover, for the first time the amino acid composition of a 3-hydroxybenzoate-6-hydroxylase was determined.

Amino Acids↗
PubMed1995

Purification and characterization of 4-hydroxybenzoate 3-hydroxylase from a Klebsiella pneumoniae mutant strain.

Unlike the parent wild-type strain, the Klebsiella pneumoniae mutant strain MAO4 has a 4-HBA+ phenotype. The capacity of this mutant to take up and metabolize 4-hydroxybenzoate (4-HBA) relies on the expression of a permease and an NADPH-linked monooxygenase (4-HBA-3-hydroxylase). Both enzymes are normally expressed at basal levels, and only the presence of 4-HBA in the media enhances their activities. Strikingly, when the Acinetobacter calcoaceticus pobA gene encoding 4-hydroxybenzoate-3-hydroxylase was expressed in hydroxybenzoate K. pneumoniae wild-type, the bacteria were unable to grow on 4-HBA, suggesting that the main difference between the wild-type and the mutant strain is the capability of the latter to take up 4-HBA. 4-HBA-3-hydroxylase was purified to homogeneity by affinity, gel-filtration, and anion-exchange chromatography. The native enzyme, which appeared to be a dimer of identical subunits, had an apparent molecular mass of 80 kDa and a pI of 4.6. Steady-state kinetics were analyzed; the initial velocity patterns were consistent with a concerted substitution mechanism. The purified enzyme had 362 amino acid residues, and a tyrosine seemed to be involved in substrate activation.

4-Hydroxybenzoate-3-Monooxygenase↗
PubMed1995

Intrapartum prophylaxis with ceftriaxone decreases rates of bacterial colonization and early-onset infection in newborns.

Because of high rates of neonatal gram-negative sepsis in many Latin American countries, we prospectively enrolled 784 high-risk pregnant women in a study designed to evaluate the effect of a single 1-g dose of ceftriaxone (n = 390) vs. that of no antibiotic prophylaxis (n = 394) on oral, rectal, and umbilical colonization and fatality rates among newborn infants. The mean ceftriaxone concentration in cord blood samples was 26 microgram/mL (range, 9-40 microgram/mL). Compared with infants of untreated mothers, children born to women who were given ceftriaxone were colonized at a lesser rate by gram-negative bacilli (54% vs. 35%; P < .001) and by group B streptococci (54% vs. 21%; P = .03) and endured significantly fewer sepsis-like illnesses in the first 5 days of life (8.1% vs. 3.1%; P = .004). There was also a tendency for them to have fewer episodes of culture-proven early-onset sepsis (2.8% vs. 0.5%; P = .06). Sepsis-related case-fatality rates (0.8% and 0.3%, respectively) were not significantly different. Although intrapartum administration of a single dose of ceftriaxone to high-risk mothers could be a safe and potentially useful strategy for reducing early-onset neonatal infections, additional information is required before this approach can be recommended for routine prophylaxis.

Bacterial Infections↗
PubMed1995

Emotional response and corticoadrenal function in anterodorsal thalami nuclei lesioned rats.

In male and female rats, the effect of limbic anterodorsal thalami nuclei lesions (ADTN) on the emotional reactivity and their relationship with corticoadrenal function were studied. The emotional reactivity was evaluated by means of the open-field test and the corticoadrenal function by means of plasma anol adrenal corticosterone concentration. The results demonstrate that, on the 8th or 9th day after the lesion, the male rats show lack of habituation and the female ones, an increase in emotional reactivity. They also indicate that the lesion of ADTN does not affect the corticoadrenal response to exposure to novel situations.

Adrenal Cortex↗
PubMed1995

Adrenal function response to chronic stress in rats with anterodorsal thalami nuclei lesions.

The effects of chronic stress (forced immobilization, 15 min/day during 12 days), on the plasma corticosterone and the adrenal catecholamines response in rats with anterodorsal thalami nuclei (ADTN) lesions were studied. In sham lesioned rats, chronic stress produced a significant increase in plasma corticosterone (C), as compared to unstressed animals (p < 0.05). The adrenal C was, however, similar in both groups. There were no differences in plasma C values between unstressed and stressed lesioned rats. The adrenal C content, was significantly lower (P < 0.005) in stressed lesioned rats when compared with unstressed lesioned animals. Adrenal norepinephrine (NE) values, in sham lesioned rats after forced immobilization, were significantly below those found in unstressed sham lesioned ones (P < 0.05). There were no changes in adrenal epinephrine (E) response after forced immobilization. In lesioned rats, NE response to chronic stress showed the opposite pattern to that in sham lesioned ones; the adrenal glands of these animals showed a significant increase in NE content as compared to unstressed lesioned rats (P < 0.01). Similar alterations in the adrenal E concentration were found, post stress values were significantly higher (P < 0.01).

Adrenal Glands↗
PubMed1995

[Parasitic and viral marker detection in pregnant adolescents and their newborn infants at risk].

We have investigated the prevalence of antibodies against Toxoplasma gondii, Trypanosoma cruzzi, Hepatitis B virus, cytomegalovirus, rubella virus, and human immunodeficiency virus in 139 adolescent pregnant women and in their high risk newborn children. The methods employed were the Sabin and Feldman reaction, complement fixation reaction, ELISA, and xenodiagnostic 30.9% of the pregnant group were seropositive for T. gondii, both mothers and newborns were IgM-negative. Two mothers (1.4%) presented anti T. cruzii antibodies, and one newborn child had circulating parasites. Related to the virological studies, 93.5% of the population were anti CMV antibodies positive and all their newborns were IgM (-) 90.6% of the adolescents were rubella positive and one was seropositive to VIH. We conclude that the prevalence found in this group of adolescent pregnant women are not significantly different to the one reported for the general pregnant women population.

Adolescent↗