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Biomedical subjects

M L García

Publications and source records attributed to M L García.

At least 55 records · Page 3Linked to original sources
PubMed1994

The closely related citrus ringspot and citrus psorosis viruses have particles of novel filamentous morphology.

Some properties of the particles of citrus ringspot virus (CtRSV) and the related citrus psorosis-associated virus (CPsAV) are described. The particles of CtRSV have been reported to be sinuous linear structures about 10 nm in diameter and of two lengths (300 to 500 nm and 1500 to 2500 nm) representing 'top' and 'bottom' sedimentation components. We show that these particles are collapsed double-stranded forms of nucleocapsid-like, highly flexuous open circles formed of filaments 3 to 4 nm in diameter. Top-component filaments had contour lengths of 600 to 1000 nm, i.e. twice that reported for the corresponding collapsed form. Bottom-component filaments had contour lengths about four times longer than those of top-component filaments. The structures suggest that CtRSV represents a new genus (possibly family) related to the tenuiviruses. However, we failed to demonstrate any serological relationship between CtRSV and several tenuiviruses; moreover, the capsid protein sizes and host ranges are quite different. We offer the name Ophiovirus for the proposed new genus.

Antibodies, Viral↗
PubMed1994

Incidence of motile Aeromonas spp. in foods.

A total of 80 food samples were purchased from local retail consumer shops and examined for the presence of motile Aeromonas spp. Of the food categories tested, poultry had the highest incidence, with 100% positive. This was followed by lamb samples, with 60% positive. Raw milk and cheese samples had very low incidence (20%). No motile Aeromonas spp. were found in pre-prepared salads. Shellfish, fish, pork and beef samples had incidences of 40%. Most of the strains isolated were Aeromonas hydrophila, and for most of the food categories, no Aeromonas caviae isolates were obtained.

Aeromonas↗
PubMed1993

Nosocomial infection in surgery wards: a controlled study of increased duration of hospital stays and direct cost of hospitalization.

Excess length of hospital stays and associated costs were assessed in patients hospitalized in the department of general and digestive surgery who acquired nosocomial infections. A prospective study of matched infected-uninfected patients nested in a cohort was used to estimate the length of the hospital stay of infected patients. Matched controls were obtained with respect to patient exact primary diagnosis, operative procedure and classification, age and, if possible, underlying disease, elective or emergency procedure and invasive devices. Superficial surgical wound infection prolonged the average hospital stay of the nosocomially infected patient by an average of 12.6 days, wound infection (deep and superficial) by 14.3 days and infections other than wound infection by 7.3 days as compared to the uninfected matched controls.

Cohort Studies↗
PubMed1993

Resistance to the antimicrobial agents of bacteria isolated from non-sterile pharmaceuticals.

The in vitro antimicrobial resistance of 391 bacterial strains isolated from 389 samples of oral and topical medicaments was examined. The numbers of strains isolated (and percentage of samples that present them) were: 234 Bacillus (32.1%), 79 Staphylococcus (13.6%), 46 Micrococcus (11.3%), nine Pseudomonas (1.5%), eight Acinetobacter (1.5%), five Enterococcus (1.2%), three Alcaligenes (0.8%), two Escherichia and Enterobacter (0.5%), one each Providencia, Serratia and Streptococcus (0.2%). Gram-positive bacteria were isolated from topical and oral medicaments and Gram-negative rods were detected only in topical medicaments. The 97.4% of Bacillus strains were resistant to lincomycin and B. cereus was resistant to beta-lactam and trimethoprim-sulphamethoxazole. Staphylococcus spp. showed a high percentage of resistant strains to ampicillin (51.8%), tetracycline (40.5%) and trimethoprim-sulphamethoxazole (48.1%). Staphylococcus epidermidis had the highest number of multiresistant strains. The 23.9% of Micrococcus strains were resistant to colistin. Enterococcus and Streptococcus strains showed multiresistance to penicillin G, aminoglycosides and erythromycin. The 61.5% of Gram-negative rod strains showed multiresistance to beta-lactam antibiotics and erythromycin; Pseudomonas spp. were the most resistant.

Bacillus↗
PubMed1992

Effect of culture age, pre-incubation at low temperature and pH on the thermal resistance of Aeromonas hydrophila.

The thermal resistance of Aeromonas hydrophila strain NCTC 8049 was determined within the range 48 degrees-65 degrees C with a thermoresistometer TR-SC and McIlvaine buffer. The effects of culture age, pre-incubation at 7 degrees C and the pH of the heating menstruum were evaluated. The pattern of thermal death was dependent on culture age. Cells heated in the late logarithmic growth phase (15 h at 30 degrees C) were twice as resistant as those in the early stage (5 h at 30 degrees C), and the maximum D-value was obtained after 72 h incubation (5.5 total increase). The age of the cells did not affect z-values significantly. The heat resistance of cells incubated for 48 h at 30 degrees C increased (twice) after holding at 7 degrees C for 72 h. Pre-incubation at low temperature of older cultures (72 h, 30 degrees C) did not influence their D-values. Maximum heat resistance was found at pH 6.0 and minimal at pH 4.0. Decreasing the pH from 6.0 to 4.0 reduced D-values by a factor of 5. Although the strain studied was heat-sensitive (D55 degrees C = 0.17 min; z = 5.11 degrees C), survivor curves of cultures older than 50 h showed a significant tailing. Organisms surviving in the tails were only slightly more resistant than were the original population.

Aeromonas hydrophila↗
PubMed1990

Production of staphylococcal enterotoxins C1 and C2 and thermonuclease throughout the growth cycle.

Synthesis of enterotoxins C1 and C2 and thermonuclease throughout the growth cycle was investigated with Staphylococcus aureus type strains FRI137 and FRI361 and S. aureus isolates M5 (C1) and L2 (C2) of animal origin. Both enterotoxins were produced during the exponential growth phase or at the beginning of the stationary phase. The minimal incubation time (7 to 12 h) and the lowest population (10(7) to 2 x 10(9) CFU/ml) associated with detectable enterotoxin (1 to 6.5 ng/ml) were related to the total amount of toxin produced after 24 h. Thermonuclease was detected in all samples whenever enterotoxins were detected. Furthermore, strain FRI137 produced thermonuclease earlier and at lower cell populations than it did enterotoxin C1. Patterns of enterotoxin and thermonuclease synthesis did not correlate. The concentration of toxins increased throughout the growth cycle, while the concentration of thermonuclease remained constant during the last hours of the growth cycle.

Animals↗
PubMed1988

Effect of growth of a commercial starter culture on growth of Staphylococcus aureus and thermonuclease and enterotoxins (C1 and C2) production in broth cultures.

Staphylococcus aureus strains FRI 137 (enterotoxin C1 producer) and FRI 361 and L 2 (enterotoxin C2 producers) were grown alone and in the presence of a mixed commercial starter culture (Streptococcus lactis, Streptococcus cremoris and Streptococcus lactis subsp. diacetylactis). Lactic acid bacteria had a slight inhibitory effect on S. aureus population and only during the late stages of growth. In contrast, enterotoxin synthesis was strongly inhibited, inhibition at 18 h being 89% (FRI 137), 80% (FRI 361) and 69% (L 2). Enterotoxin C1 was produced and accumulated during all phases of growth in pure and mixed culture, but associative growth resulted in reduction of enterotoxin C2 after 24-36 h. In mixed culture, high producers of thermonuclease (FRI 137 and L 2) showed an early decrease in enzyme activity followed by an increase, but it never reached levels attained in pure culture. Thermonuclease was detected whenever enterotoxin was detected, but production curves did not parallel each other.

Bacteriological Techniques↗
PubMed1988

Tear pH, air pollution, and contact lenses.

We analyzed the tear pH of a random sample of 100 subjects, divided into 3 groups according to the stability of their precorneal tear film (normal eyes, borderline; and dry eyes). The average pH value obtained was 7.52. The pH for borderline and dry eyes was higher than for normal eyes. The purpose of this study was to determine the influence of air pollution, specifically sulfur dioxide (SO2), on the tear pH. We found that air pollution affected the lacrimal pH, which decreased when the atmospheric SO2 increased. Finally, we studied the effect of soft contact lens wear on tear pH after 7 days of contact lens adaptation by assessing the tear pH decrease. We took into account the influence of the sex and age of subjects on the results obtained.

Adolescent↗
PubMed1988

Behaviour of Staphylococcus aureus strains, producers of enterotoxins C1 or C2, during the manufacture and storage of Burgos cheese.

Burgos cheese was manufactured from pasteurized ewes' milk inoculated with Staphylococcus aureus strains FRI 137 and FRI 361, at levels of ca 10(3) and 10(5) cfu/ml and stored at 4 degrees, 10 degrees and 15 degrees C and at room temperature (10 degrees-15 degrees C). Populations of Staph. aureus and mesophilic aerobes, pH, and production of thermonuclease and enterotoxins C1 and C2 were investigated. Aerobic counts increased during cheese-making and storage. With both test strains, important growth was observed only during the storage period, the larger levels corresponding to the higher temperatures. Although Staph. aureus strains attained populations of over 10(8) cfu/g, no enterotoxin was detected. Strain FRI 361 reached 10(7) cfu/g without production of a detectable amount of thermonuclease. With strain FRI 137, the minimal population associated with enzyme activity was influenced by the inoculum size. Staphylococcus aureus counts are better indicators of staphylococcal growth in Burgos cheese than the thermonuclease test.

Aerobiosis↗
PubMed1987

Relationships between physico-chemical parameters and microbial groups in Manchego and Burgos cheeses studied by principal component analysis.

Principal component analysis was used to examine the correlations between two sets of variables, one representing physicochemical characteristics (pH, aw and NaCl, moisture and fat content) of Manchego (36 samples) and Burgos (36 samples) cheeses, and the other representing counts of several microbial groups (mesophiles, psychrotrophs, lactic acid bacteria, coliforms, enterococci, staphylococci and molds and yeasts). Thermonuclease content was also included. In addition to the expected relationships (NaCl content, moisture, aw, etc.), significant correlations between some compositional characteristics and levels of certain microorganisms were found. These correlations were dependent on the type of cheese. Thermonuclease content was positively related to enterococci and ripening (only in Manchego cheese). In contrast to former observations, no relationships were observed between coliforms and enterococci counts.

Cheese↗
PubMed1985

Importance of food handlers as a source of enterotoxigenic staphylococci.

The incidence of staphylococci in the nasal fossae of 300 food handlers working within the province of León (Spain) was studied. Sampling was carried out using a swabbing technique. For the quantitative estimation of staphylococci, a direct plating method and an enrichment procedure (MPN) were used simultaneously. Gram positive cocci that fermented glucose and were sensitive to lysostaphin (1 unit/ml) were found to be present in the noses of 201 food handlers (67%). Eighty three of them (27.6%) were carriers of coagulase positive staphylococci and 118 (39.3%) of coagulase negative staphylococci. The carriage rate of coagulase negative staphylococci was slightly higher in winter but carriers of coagulase positive strains were more frequently found during warmer months. Coagulase positive staphylococci appeared to be more often carried by males. In all instances, positive nasal cultures gave 10 or more colonies per sample. The majority of food handlers carrying coagulase negative staphylococci (64.4%) yielded counts between 10(3)-10(5) CFU per swab. Thirty four (40.9%) of the nasal carriers of coagulase positive staphylococci yielded more than 10(4) CFU per sample. The higher counts corresponded to this latter group. Preliminary enrichment did not increase the number of nasal carriers detected. Although a good correlation was observed between the results of direct plating and the MPN procedure (r = 0.87 +/- 0.04), the MPN technique gave lower counts. Thirty six (12%) individuals carried enterotoxigenic staphylococci. The incidence among carriers of coagulase positive strains was 43.4%. The enterotoxin types produced were: A (12 strains), B (8 strains), C (7 strains), D (2 strains), E (2 strains), A + D (4 strains) and B + C (1 strain). Most of the food handlers who harbored enterotoxigenic strains gave high nasal counts.

Carrier State↗
PubMed1981

Inhibition by methylmalonate of glycine uptake by synaptosomes from rat spinal cord.

Methylmalonate is accumulated in the genetically linked deficiency of methylmalonyl-CoA mutase (methylmalonic acidemia). In this condition is also observed an elevation of the glycine levels. This communication reports the inhibition of the synaptosomal glycine uptake by methylmalonate, when present at similar concentrations to those found in methylmalonic acidemia. This inhibition could be responsible, at least in part, for the neurological damage characteristic of this disease, by increasing the glycine levels in the synaptic cleft and thus interfering with the normal function of the inhibitory glycinergic synapsis in the spinal cord.

Amino Acid Metabolism, Inborn Errors↗
PubMed1980

Occurrence of a reduced nicotinamide adenine dinucleotide oxidase activity linked to a cytochrome system in renal brush border membranes.

NADH oxidase activity has been detected in luminal membrane derived from the proximal tubules of rat kidney (brush border membranes). The cytochromes associated with these membranes [García, M.L., Benavides, J., Valdivieso, F., Mayor, F., & Giménez-Gallego, G. (1978) Biochem. Biophys. Res. Commun. 82, 738-744] were reduced by NADH, the extent of this reduction being affected by the presence of oxygen and by inhibitors of this NADH oxidase activity. These results suggest that the cytochromes act as an electron transport system between NADH and oxygen. The possibility of mitochondrial contamination is excluded on the basis of differential sensitivity to inhibitors and marker enzyme activities.

Animals↗