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Biomedical subjects

M A Garcia

Publications and source records attributed to M A Garcia.

At least 19 recordsLinked to original sources
PubMed1996

Importance of sodium ion to the progesterone-initiated acrosome reaction in human sperm.

Progesterone (P) has previously been shown to rapidly increase free intracellular calcium concentration ([Ca2+]i), and subsequently to initiate the acrosome reaction (AR) in capacitated human sperm. The present study used cytochemical analysis of the AR, and spectrofluorometric determination of sperm [Ca2+]i and intracellular pH (pHi) in Na(+)-containing and Na(+)-deficient bicarbonate/CO2-buffered media to investigate the role of Na+ in these P-initiated changes. We found that P failed to initiate the AR in Na(+)-deficient medium, and that the initial rise in [Ca2+]i following P (1 microgram/ml) stimulation was similar for both media; however, the [Ca2+]i in the Na(+)-deficient medium regressed more rapidly and plateaued at a significantly lower [Ca2+]i. Moreover, the differences in plateau [Ca2+]i were directly related to the percentage of acrosome reactions, suggesting that the plateau phase is not due to [Ca2+]i, but rather to the release of intracellular fura-2 into the medium during the AR. These [Ca2+]i, and AR results are in contrast to those reported previously by others for human sperm and suggest that a Na(+)-dependent mechanism is important in the P-initiated human sperm AR. Such a Na+ requirement may reflect the involvement of this ion in pHi regulation, as capacitated sperm that were incubated in a Na(+)-deficient medium for > or = 30 min displayed a significantly lower pHi.

Acrosome↗
PubMed1996

RT-PCR without RNA isolation.

Reverse transcription-PCR (RT-PCR) has traditionally required time-consuming RNA extraction and purification. This report demonstrates that one can completely avoid the RNA extraction step in RT-PCR by basing the comparison of samples on cell number rather than micrograms of total RNA. A new method for lysing cells while preserving RNA is described. RT-PCR is carried out (i) by rapidly freezing cells in the presence of ribonuclease inhibitor (RNase inhibitor) plus dithiothreitol and (ii) by using extracts of 250 or fewer cells directly in the RT-PCR assay. Aldolase mRNA, extracted by freeze-thawing cells in the presence of RNase inhibitor, was found to be stable at 42 degrees C for over three hours. Since the RT step can be completed within 1 h, there is minimal degradation of mRNA. This simple procedure avoids the use of harsh reagents, which may inhibit enzymes involved in RT-PCR, and produces results virtually identical to methods that employ guanidinium thiocyanate and phenol for RNA extraction. Optimized conditions for each parameter of the procedure are described that permit amplification of mRNA from as few as four cells.

Freezing↗
PubMed1995

DNA aneuploidy in acute myeloblastic leukemia is associated with a high expression of lymphoid markers.

In the present study the DNA cell content of 205 de novo acute myeloblastic leukemia (AML) patients is analyzed at flow cytometry in order to determine both the incidence of DNA aneuploidy in AML patients and the clinical and biological characteristics of AML aneuploid cases. All technical procedures were performed in accordance with the proposed guidelines of the DNA Cytometric Consensus Conference. Our results show that the incidence of DNA aneuploidy is quite low (4.8%), with most cases (n = 8) hyperdiploid and only a small proportion (n = 2) hypodiploid. No major differences were detected between the aneuploid and diploid cases with respect to the clinical and prognostic disease characteristics. Regarding the immunophenotype of the blast cells, the aneuploid cases displayed both a higher incidence of immature myeloblastic phenotype and a greater expression of lymphoid-associated antigens. In summary, our results show that AML patients display a quite low incidence of DNA aneuploidy and that despite the fact that these cases do not display particular clinical characteristics, they show an association with the expression of lymphoid-related markers.

Adult↗
PubMed1995

Program planning: a total quality approach.

1. Deming's concepts for total quality management/continuous quality improvement are the basis for a tool occupational health nurses can apply in health program planning. 2. The program planning model provides a framework for systematically implementing, evaluating, and improving products and services. In the current business environment, this is critical to success and to demonstration of the value of occupational health services to a company. 3. A case study describing implementation of a medical case management program illustrates application of the model in a real life situation.

Humans↗
PubMed1994

Comparison of derivatization procedures for the determination of diuretics in urine by gas chromatography-mass spectrometry.

Three different GC-MS screening procedures, which use different ways of derivatization (methylation), are compared. In the first one, derivatization with iodomethane in acetone and a previous solid-liquid extraction is used; the second one is based on an extractive alkylation method using iodomethane in toluene (liquid-liquid extraction); and the last one is flash methylation by pyrolysis of tetraalkylammonium salts in the injector of the gas chromatograph using trimethylanilinium as the derivatization agent. The speed of the extraction, reproducibility and accuracy have been compared for 20 diuretics including the ones most often used in sports, such as bumetanide, ethacrynic acid, acetazolamide, dichlorphenamide, furosemide, hydroflumethiazide, hydrochlorothiazide and chlorthalidone; they have also been applied to the two uricosuric agents probenecid and benzbromarone.

Diuretics↗
PubMed1994

Comparative evaluation of pentoxifylline, buflomedil, and nifedipine in the treatment of intermittent claudication of the lower limbs.

In the light of the current controversy surrounding the use of hemorheologic and vasodilator drugs in the treatment of peripheral arteriosclerosis, a comparative study was designed in order to evaluate the efficacy of pentoxifylline, buflomedil, and nifedipine in 45 patients with peripheral arterial disease (Fontaine stage II). The patients in this prospective randomized study were divided into three groups: 15 patients received pentoxifylline treatment (1,200 mg/day), 15 were treated with buflomedil (600 mg/day), and 15 with nifedipine (60 mg/day). Response to treatment was assessed at the start of the study and after forty-five and ninety days, by clinical examination, Doppler test, strain test, and digital occlusion plethysmography using a strain gauge ring. Pentoxifylline was significantly more effective (P < 0.05) than buflomedil and nifedipine at ninety days in improving walking performance, resting toe pressure, resting and postexercise ankle/brachial pressure ratio, and basal/postischemic toe-pulse ratio. Significant differences within groups were also noted for initial claudication, toe peak-flow time, pulse reappearance time (PRT/2), and maximum postischemic flow time, together with significant intergroup variables. In conclusion, pentoxifylline proved more effective than the other drugs tested in: 1. improving distal pressure and resting microcirculatory blood flow; 2. increasing postexercise distal flow, ratios, and pressures and enabling faster recuperation of basal pulse rates; 3. increasing initial claudication distance in the strain test within the test group and achieving a greater absolute subjective claudication distance than that obtained using the other treatments.

Adult↗
PubMed1994

Placental transfer of enrofloxacin and ciprofloxacin in rabbits.

Placental transfer of enrofloxacin and ciprofloxacin was evaluated, using a rabbit in situ perfusion model. A two-step infusion program was carried out to obtain steady-state maternal plasma concentrations of these drugs. For each compound, the placenta in 5 rabbits was perfused for 200 minutes with Earle's enriched bicarbonate buffer at flow rate of 1.5 ml/min. To assess reliability of the model, most of the determinants of placental transfer (maternal and fetal pH, gas balance, heart status, rectal temperature, and protein binding) were controlled. In addition, the infusion program included administration of antipyrine, a commonly used indicator of placental exchange. Drug concentrations were measured in maternal plasma and perfusate by use of a high-performance liquid chromatographic assay. Plasma protein-binding estimation indicated no differences between the drugs. Placental clearance of the drugs was significantly (P < 0.01) different (0.88 +/- 0.13 ml/min for enrofloxacin and 0.06 +/- 0.02 ml/min for ciprofloxacin). These values accounted for 81 and 5%, respectively, of the placental clearance found for antipyrine. These results indicate that caution must be taken when enrofloxacin is to be used during pregnancy, and suggest the need to extend this type of experiment to species that can be exposed to these drugs used for therapeutic or prophylactic purposes.

Animals↗
PubMed1993

Collaborative practice: a shared success.

A community hospital reflects on changes made when implementing a collaborative practice theory. Using a philosophy that called both professional groups to "share and work together to provide thorough and consistent patient care," a successful joint practice was operational within a year.

Colorado↗
PubMed1992

Status of cryopreservation of embryos from domestic animals.

The discovery of glycerol as an effective cryoprotectant for spermatozoa led to research on cryopreservation of embryos. The first successful offspring from frozen-thawed embryos were reported in the mouse and later in other laboratory animals. Subsequently, these techniques were applied to domestic animals. Research in cryopreservation techniques have included studies concerning the type and concentration of cryoprotectant, cooling and freezing rates, seeding and plunging temperatures, thawing temperatures and rates, and methods of cryoprotectant removal. To date, successful results based on pregnancy rates have been obtained with cryopreserved cow, sheep, goat, and horse embryos but no success has been reported in swine. Post-thaw embryo survival has been shown to be dependent on the initial embryo quality, developmental stage, and species. The freezing techniques most frequently used in research and by commercial companies are identified as "equilibrium" cryopreservation. In this technique the embryos are placed in a concentrated glycerol solution (1.4 M in PBS supplemented with BSA) at room temperature and the glycerol is allowed to equilibrate for a 20-min period. During the cooling process the straws are seeded (-4 to -7 degrees C) and cooling is continued at a rate of 0.3 to 0.5 degree C/min to -30 degrees C when bovine embryos may be plunged into LN2. Sheep embryos are successfully frozen with ethylene glycol (1.5 M) or DMSO (1.5 M) rather than with glycerol. Horse embryos have been frozen in 0.5 rather than 0.25 cc straws but with cooling rates and seeding and plunging temperatures similar to those used with bovine embryos. Swine embryos have shown a high sensitivity to temperature and cryoprotectants probably due to their high lipid content and a temperature decrease to 15 or 10 degrees C causes a dramatic increase in the percentage of degenerated embryos. However, a recent study has shown that hatched pig blastocysts survived exposure below 15 degrees C. Recent research has shown that embryos may also be frozen by a "nonequilibrium" method. This rapid freezing by vitrification consists of dehydration of the embryo at room temperature by a very highly concentrated vitrification media (3.5 to 4.0 M) and a very rapid freeze that avoids the formation of ice allowing the solution to change from a liquid to a glassy state. Vitrification solutions consist of combinations of sucrose, glycerol, and propylene glycol. With this technique, 50% pregnancy rates have been reported with the bovine blastocyst.

Animals↗
PubMed1991

Lead and zinc protoporphyrin in the blood of a rural child population in Asturias, Spain.

Lead and zinc protoporphyrin were determined in the blood of 54 children aged from 2 to 14 years living in a rural area of west Asturias (Spain). Mean values found were 14.4 and 27.7 micrograms dl-1, respectively. Blood lead levels are considerably lower than those of children living in central Asturias, which is more highly industrialised, showing the large part played by industry and road traffic in increasing both parameters.

Adolescent↗
PubMed1991

Enterotoxigenic Escherichia coli associated with infant diarrhoea in Galicia, north-western Spain.

To assess the role of enterotoxigenic Escherichia coli (ETEC) in infantile diarrhoea, 482 children with diarrhoea and 103 healthy controls, from three localities of Galicia, north-western Spain, were investigated between 1985 and 1988. Rotavirus (37.3%) and Salmonella spp. (12.8%) were the most common causal agents, followed by ETEC (3.9%), Campylobacter jejuni (2.3%), Shigella spp. (0.9%) and Yersinia enterocolitica (0.5%). ETEC were significantly more frequently isolated from children with diarrhoea who were under 1 month of age (26.5%) than from older diarrhoeic children (2.2%) (p less than 0.001) or from healthy children who were under 1 month of age (0%) (p less than 0.05). Among children who harboured ETEC, five of the nine children under 1 month of age developed diarrhoea in hospital, whereas none of the 10 children over 1 month of age did so. Seventeen ETEC isolates produced heat-stable enterotoxin (STa) only, four produced only heat-labile enterotoxin (LT), and two produced both toxins. Colonisation factor antigens CFA/I and CFA/II were detected in 11 (55.0%) of the 20 ETEC isolates that remained enterotoxigenic after maintenance in the laboratory. Most ETEC isolates belonged to serotypes O153:K-:H45 (nine STa+ CFA/I+ isolates), O27:K-:H7 (three STa+ isolates) or O6:K15:H16 (two LT+ STa+ CFA/II+ isolates). Our results suggest that ETEC constitute an important cause of neonatal diarrhoea in this part of Spain.

Antigens, Bacterial↗
PubMed1990

Structural studies on allergen RC-13 from Ricinus communis L.: isolation and characterization of a major glycopeptide.

A glycoprotein, RC-13, isolated from Ricinus communis seeds was reduced, S-alkylated and cleaved by trypsin. The tryptic digest was fractionated by ion-exchange chromatography and a glycopeptide was isolated and purified by high-voltage paper electrophoresis. When submitted to amino acid and carbohydrate analyses this major glycopeptide showed the following chemical composition: Lys1, Asp1, Thr2, Ser4, Glu1, Pro2, Gly2, Ala2, Val2, GlcN6, Man6 and Gal8. Hydrazynolysis positioned Ser as the C-terminal residue. It is postulated that this glycopeptide belongs to the C-terminal region of the allergen.

Allergens↗
PubMed1989

Sexual behavior changes and HIV antibody in a cohort of New York City gay men.

A sample of 357 gay/bisexual men, ages 20 to 65, were interviewed in 1985 regarding their sexual patterns over the course of the AIDS (acquired immunodeficiency syndrome) epidemic. Within four months after the interview, men were tested for antibody to HIV (human immunodeficiency virus) and 36 per cent were found positive. Cessation of receptive anal intercourse was associated with HIV negative antibody status, (OR greater than 3.0). Reducing the number of sexual partners, becoming monogamous, or eliminating other forms of sexual contact were not related to risk of HIV.

Acquired Immunodeficiency Syndrome↗
PubMed1987

Effects of low-molecular-weight fractions (LMWF) from milk, egg yolk, and seminal plasma on freezability of bovine spermatozoa.

The effects of the dialyzable fractions from bovine seminal plasma, egg yolk, and milk and of two buffer systems (TEST and sodium citrate) on post-thaw sperm motility were studied. Each basic salt solution was used in the experimental design. These solutions were used as extender systems in combination with egg yolk and glycerol. After collection, semen samples were extended (1:20), cooled to 5 degrees C in 1.5 hr, and frozen in 0.5-cc French straws after 3 hr of equilibration. Post-thaw samples were assayed for percentage of motile cells immediately after thawing and after 4 hr of incubation at room temperature (22 degrees C). Egg yolk (25%) provided the same protection as did the combination of colloidal material present in the skim milk-yolk extenders. The use of TEST as a buffer provided significantly higher (P less than 0.01) sperm post-thaw motility than milk salts or Na citrate. Sperm survival in extenders containing high concentrations of seminal plasma and/or egg yolk salts was significantly lower (P less than 0.01). Spermatozoa frozen in the presence of 6% glycerol resulted in sperm motility significantly (P less than 0.05) higher than that of spermatozoa frozen with 3% glycerol. However, no difference was observed between these two concentrations when TEST solution was used.

Animals↗