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Biomedical subjects

G García

Publications and source records attributed to G García.

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

Increased cytogenetic damage in outdoor painters.

Painters are exposed to an extensive variety of hazardous substances such as organic solvents, lead-containing pigments and residual plastic monomers. In this particular case, workers used commercially available exterior paints and occasionally gasoline or thinner as solvents. The application or removal of paints was performed without protection (masks or gloves). To determine occupational exposure risk, a monitoring study was designed. Group selection was made after a questionnaire administration, which included questions about lifestyle and medical history to exclude exposure to other potential sources of genotoxics. Smoking and drinking habits were also considered. Blood and buccal cell samples were obtained from 25 public building male painters and from a similar number of age- and gender-matched controls. Lead levels were measured in paint samples and in individuals' blood. Organic solvents and/or its metabolites were also determined in blood. Chromosomal aberrations (CA) and sister chromatid exchanges (SCE) were determined in peripheral blood lymphocyte cultures. Also, the frequency of micronuclei (MN) in buccal cells was investigated. Painters had higher lead levels in blood (p<0.05); CA and SCE in lymphocytes and MN in epithelial cells were also elevated (p<0.05). Cytogenetic damage was significantly associated with occupational exposure time but not with the levels of lead found in blood.

Adolescent↗
PubMed2000

Multicenter retrospective study of response to interferon in chronic hepatitis B.

AIM: The only agent known to have a lasting beneficial effect in chronic hepatitis B is interferon alpha, which achieves long-term remission in 25-40% of the patients. The goals of treatment are to induce clearance of HBV DNA from serum, to return serum aminotransferases to normal, and to improve histological findings in the liver. The most important factors predictive of response to treatment are high serum aminotranferases levels, low serum HBV DNA concentrations, and active histologic changes on liver biopsy. The aim of this study was to assess the response to interferon alpha in patients with chronic hepatitis B and to analyze the factors predictive of response. METHODS: We conducted a multicenter retrospective study to investigate the effect of interferon treatment in 132 patients with chronic hepatitis B in overall terms and based on HBeAg, and factors predictive of response. RESULTS: A overall sustained response was noted in 59 of 132 interferon-treated patients (45%) and 61 patients were nonresponders (46%). 12 patients relapsed (9%). None of the patients had negative HBsAg. No difference was observed in the response rate between the two treatment groups (HBeAg-positive and HBeAg-negative patients). Overall, high initial levels of serum AST and ALT predicted a good response. Age and liver biopsy findings were factors predictive of response in HBeAg-positive and HBeAg-negative patients respectively. Sex, epidemiological factors, treatment and type of virus did not correlate with the response to interferon. CONCLUSIONS: A sustained response to interferon alpha was observed in 45% of the patients with chronic hepatitis B. HBeAg seroconversion was found in up to 50% of HBeAg-positive patients. None of the patients had negative HBsAg. Overall, the response rate was higher in patients with high pretreatment serum aminotransferase levels. Age was the predictive factor in HBeAg-positive patients, and histological features were predictive in the HBeAg-negative group. However, further studies in a larger patient population are necessary to obtain well-substantiated conclusions.

Adolescent↗
PubMed2000

[Impact of an anti-hepatitis B virus (HBV) immunization program in patients undergoing dialysis in Havana, Cuba].

The follow-up of HBV markers in selected high infection risk populations, in patients from the hemodialysis and peritoneal dialysis services was used to assess the effectiveness of a special vaccination program. Viral infection markers were studied in prevalence cross sections of the whole population of patients, and also by recording the reports of clinical cases of hepatitis B occurred during that period in those groups of patients. The prevention program consisted of the vaccination of all patients negative to the viral markers and the indication of vaccination for the new cases during the period of the kidney disease, just before the start of the treatment at the hemodialysis unit; besides all the persons susceptible to infection that had already been included in the program, regardless of the stage of the disease. The results show the benefit of the vaccination in these patients, but it is more effective in the period before the treatment with dialysis where there is a lower possibility of being exposed to the virus and the immune system is still competent. Once the program was established, after a follow up o 6 years, there have been no reports of new cases of hepatitis B and the incidence of the disease has been declining.

Adult↗
PubMed1999

Evidence that antisulfatide autoantibodies from rats experimentally infected with Trypanosoma cruzi bind to homologous neural tissue.

Earlier studies in Trypanosoma cruzi-infected rats revealed an increased antibody activity against sulfatide, a specific constituent of both myelin sheaths of peripheral nerves and T. cruzi epimastigotes. To investigate further the characteristics of such anti-sulfatide antibodies, we analyzed their IgG isotypes as well as their ability to bind to homologous neural host structures. Antisulfatide IgG-enriched fractions were obtained from rats acutely infected with T. cruzi. Immunoglobulin isotypes were determined by an enzyme-linked immunosorbent assay (ELISA) method to show that IgG2a and, more significantly, IgG2b were the predominant isotypes of antisulfatide autoantibodies. Further immunofluorescence studies carried out in coronal sections of the rat forebrain revealed, in turn, that antisulfatide antibodies were capable of reacting with homologous neural tissues. Specific binding of these rat autoantibodies to sulfocerebroside on cell surfaces in vivo may in theory play some detrimental role, given the reported ability of rat IgG2b to fix complement or to mediate antibody-dependent cell-mediated cytotoxicity reactions.

Acute Disease↗
PubMed1999

Heparin plus aspirin as a "single" therapy for recurrent spontaneous abortion associated with both allo- and autoimmunity.

PROBLEM: The aim of this study was to contribute to the study of the pathogenesis and the treatment of recurrent spontaneous abortion (RSA) associated with immune alterations. METHOD OF STUDY: This is a prospective clinical trial with 11 patients with RSA associated with allo- and autoimmunity not receiving lymphocyte immunizations but only heparin and aspirin preconceptionally and through pregnancy. A concurrent group of 8 patients receiving a complete therapy (lymphocyte immunizations, heparin, and aspirin) but not receiving heparin and aspirin preconceptionally is also included in this report. RESULTS: The rate of pregnancy success in these patients was 90.9% (10/11), and the rate of success of the concurrent group was 75.0% (6/8). CONCLUSIONS: The results are in agreement with the working hypothesis regarding the possible final common mechanism in the pathogenesis of abortion associated with allo- and autoimmunity. The "single" therapy with heparin and aspirin was effective, less costly, and logistically simpler to provide than a complete therapy including lymphocyte immunizations.

Abortion, Habitual↗
PubMed1998

Diagnosis of porcine cysticercosis: a comparative study of serological tests for detection of circulating antibody and viable parasites.

Epidemiological studies of porcine cysticercosis require identification of pigs harbouring viable Taenia solium cysticerci and estimates of the degree of exposure to the parasite in the pig population destined for human consumption. Identification of infected pigs with viable larvae is achieved through detection of their secretory products. However, detectable levels of circulating antibody may also be present in the absence of viable larvae. In this study, both types of tests have been evaluated in groups of pigs experimentally infected with T. solium. Detection of viable cysticerci was achieved using a monoclonal antibody-based (HP10) antigen capture assay. HP10 epitope-bearing antigens have now been demonstrated in T. solium and T. crassiceps cyst fluid and excretion/secretions. Serum antibodies were measured in ELISA assays using two parasite preparations as antigens; T. solium cyst fluid and T. crassiceps cyst fluid antigens bearing the HP10 epitope. Low-background values were obtained with sera from non-infected animals in all the assays used. In heavily infected pigs, both antigens and antibodies were detected at least 29 days and up to 200 days post-infection (pi), while in lightly infected pigs antigen and antibodies were first observed between 61-97 days pi. Thus, the levels of the serum antigen and antibody varied with the intensity of the infection.

Animals↗
PubMed1998

Comparative morphofunctional study of dispersed mature canine cutaneous mast cells and BR cells, a poorly differentiated mast cell line from a dog subcutaneous mastocytoma.

The dog mastocytoma BR cell line provides us with a permanent source of canine mast cells, allowing a characterization of secretory mediators that exert important effects in canine allergic and nonallergic diseases and in physiological processes. We studied the ultrastructural characteristics and histamine releasing activity after immunological and non-immunological stimuli of the dog mastocytoma BR cell line, and compared the cell line to normal skin mast cells enzymatically isolated from healthy dogs. The histamine content of BR cells was 0.04 +/- 0.002 pg/cell, approximately 100-fold less than that found in canine skin mast cells. Non-immunologic stimuli induced similar concentration-dependent histamine release from skin mast cells and BR cells: 29.3 +/- 0.9% vs. 12.7 +/- 0.7% (calcium ionophore A23187), 23.3 +/- 0.7% vs. 18.8 +/- 0.7% (substance P) and 12.5 +/- 0.3% vs. 12.1 +/- 0.9% (compound 48/80), respectively. Immunologic stimulation, however, was only effective on canine skin mast cells, causing 30.9 +/- 1.7%, 27.7 +/- 0.6% and 12.2 +/- 0.9% histamine release in response to anti-canine IgE, concanavalin A, and antigen Asc S 1, respectively. The absence of functional IgE receptors in BR cells was confirmed by the lack of response to anti-IgE and antigen Asc S 1 following passive sensitization with dog atopic serum and dog antigen sensitized serum. We conclude that BR cells are able to release histamine after non-immunologic stimulation in a similar manner to canine skin mast cells, but that there are morphological and functional differences possibly due to different states of maturity or differentiation. For this reason the study of the highly homogeneous BR cells could offer insights into dog mast cell biology in contexts where freshly isolated cells cannot be used because of low purity and recovery.

Animals↗
PubMed1998

Serum eosinophilic cationic protein may predict clinical course of wheezing in young children.

Thirty eight children aged between 2 and 4 years with three or more episodes of wheezing were studied to evaluate the role of eosinophil inflammation and its relation to persistence of wheezing two years later. Serum eosinophilic cationic protein, total eosinophil count, total IgE, skin prick test, and clinical features were evaluated at visit 1. Two years later at a second clinical evaluation the children were separated into two groups: group 1, those with persistent wheezing (n = 20); group 2, those who had been asymptomatic over the past six months (transient wheezing) (n = 18). Mean (SEM) eosinophilic cationic protein at visit 1 was higher in group 1 than in group 2 (29.63 (5.16) v 14.42 (2.77) micrograms/l), and the probability of continuing wheezing at age 5 years was greater in children with values > or = 20 micrograms/l at visit 1 than in those with lower values (relative risk = 2.88, 95% confidence interval 1.42 to 5.87, p < 0.001). Eosinophil inflammation is present from the beginning of the disease in the children who are going to continue with wheezing at age 5 years. The measurement of serum eosinophilic cationic protein may help in evaluating which wheezing infants are going to continue with asthma in the future.

Asthma↗
PubMed1998

[A comparative study between different regimens for administering 2 doses of the Cuban anti-hepatitis B vaccine].

A controlled clinical trial, corresponding to stage 2, was conducted in a population of sound adult males aged 18-23 to evaluate the immunogenicity of 5 schedules of Cuban vaccine against hepatitis B (Heberbiovac-HB [correction of Cheberbiovac-HB]). 5 groups were studied: I (control group 0, 1 and 6 months), II (0 and 2 months), III (0 and 4 months), IV (0 and 6 months), and V (0 and 8 months). The results showed no significant differences as regards the percentage of seroprotection of any of the groups of 2 doses compared with the control of 3 doses. It is concluded that between the first and the second dose there may be a period of time from 2 to 6 months with no need to reinitiate the schedule. This information will serve as a basis for a population based study to determine which schedule is the best to be used.

Adolescent↗
PubMed1997

2,4-dichlorophenoxyacetic acid through lactation induces astrogliosis in rat brain.

Comparison of astroglial immunoreactivity in mesencephalon, cerebellum, and hippocampus of 25-d-old rat pups exposed to 2,4-dichlorophenoxyacetic acid (2,4-D) through the mother's milk was made using a quantitative immunohistochemical analysis. A glial reaction was detected at the level of serotonergic nuclei and extreme astrogliosis in the hippocampus and cerebellum. A quantitative analysis of reactive astrocytes was performed by using GFAP and S-100 protein as specific markers. The study showed a significant increase in their number, size, number of processes, and density of immunostaining in 2,4-D-exposed animals. Exposure to 2,4-dichlorophenoxyacetic acid on the first days of life modifies the astroglial cytoarchitecture in parallel to previously described neuronal changes.

2,4-Dichlorophenoxyacetic Acid↗
PubMed1997

Destabilization of human serum albumin by polyethylene glycols studied by thermodynamical equilibrium and kinetic approaches.

Both polyethylene glycols (PEG) of MW 8,000 and that of 10000 stabilize the native compact state of human albumin showing negative preferential interaction with the protein. Interaction between these polymers and the protein is thermodynamically unfavorable, and becomes even more unfavorable for denatured protein whose surface areas are larger than those of native ones. PEG of low MW 1000 and 4000 did not show steric exclusion, interacting favorably with hydrophobic side chains made available when the protein was unfolded and leading to a stabilization of the unfolded state, which is manifested as a lowering of the thermal transition temperature. Perturbation of the absorption spectrum of albumin by PEGs confirms that at high temperature the polymers preferentially interact with the denatured state of albumin, but is excluded from the native state at low temperature. This observation is consistent with the fact that PEG is hydrophobic in nature and may interact favorably with the hydrophobic side chain exposed upon unfolding. The lower activation energy for thermal unfolding in the presence of PEG 1000 is in favour of preferential interaction of this polymer with human albumin. PEG of low MW favours the ionization of the tyrosine residues of albumin. It is apparent that pKa decreased with the increase in MW of synthetic polymer. Such variation might be a consequence of the change in dielectric constant at the domain of the protein by PEG binding.

Guanidine↗
PubMed1997

Cell microchimerism in patients with recurrent spontaneous abortion: preliminary results.

The goal of this study was to determine the prevalence of non-host male cell microchimerism in a group of women with a history of recurrent spontaneous abortion (RSA). The detection of male cell microchimerism was based upon amplification of a fragment of Y chromosome DNA obtained from peripheral blood mononuclear cells from the mother. The amplification products were electrophoresed, transferred onto nylon membranes and hybridized with a specific 32P-labelled probe. The products were visualized by autoradiography. Seventy-seven patients with RSA were studied. Some patients (42.8%) had received immunotherapy for RSA using live mononuclear cells from male donors. Of the 77 patients 46 (59.7%) were positive for the selected Y chromosome sequence, 22 (28.6%) had no evidence of Y chromosome DNA and in nine (11.7%) cases the chimeric status could not be defined since the amplified band was too faint to be clearly assigned as positive. Twenty patients were pregnant at the time of sampling. There were no statistically significant differences among the different variables studied: age of the mother, number of previous pregnancies, number of previous immunotherapeutic inoculations or period of time between the last inoculation and sampling. Male cell microchimerism has been reported in some but not all women who have given birth to male children. The dynamics for the establishment of this chimeric status and its persistence have not been defined. We found that most patients with RSA (59.7%) were positive for microchimerism but that this could not be correlated with abortion, current pregnancy or leukocyte immunotherapy. A prospective study is being undertaken to determine if there is a subset of patients negative for chimerism who become positive after alloimmunotherapy with male lymphocytes and have an improved prognosis for successful pregnancy.

Abortion, Habitual↗
PubMed1997

Effect of H1-antihistamines on histamine release from dispersed canine cutaneous mast cells.

OBJECTIVE: Because of the implication of histamine in canine atopic dermatitis, H1-antihistamines may provide a valid alternative to glucocorticoid therapy. In vitro study of these drugs prior to clinical testing can allow the most promising compounds to be selected for trials and render trials with drugs of doubtful efficacy unnecessary. SAMPLE POPULATION: Isolated canine cutaneous mast cells. PROCEDURE: Cells were preincubated with antihistamines at increasing concentrations and incubated with concanavalin A (1,000 micrograms/ml), calcium ionophore A23187 (1 microM), and substance P (100 microM). Compound 48/80 was not used because it proved to be cytotoxic. RESULTS: Generally, significant prodegranulating effect was not observed for most of the studied agents. Only terfenadine increased spontaneous histamine release at concentrations > 30 microM. Cetirizine did not block histamine release at any of the studied concentrations. Ketotifen had a low inhibitory effect only at the highest concentration (100 microM) after concanavalin A- (23.6 +/- 2.8%) and calcium ionophore A23187- (29.8 +/- 3.0%) induced release. Terfenadine caused a concentration-dependent inhibitory effect after ionophore A23187- (48.1 +/- 2.2%) and concanavalin A- (28.9 +/- 2.3%) activation, but was inactive against substance P-induced release. In contrast, loratadine had potent dose-dependent inhibition of concanavalin A- and ionophore A23187-induced histamine release, with maximal effect of 85.6 +/- 3.1% and 62.6 +/- 4.7%, respectively, at 100 microM concentration. After substance P activation, histamine release was only slightly inhibited by loratadine (14.8 +/- 1.1%). CONCLUSIONS: This study documents the behavior of isolated canine cutaneous mast cells in the presence of nonimmunologic stimulation. Using this in vitro method, we were able to determine that loratadine is the only antihistamine that has potent inhibition of histamine release from dog cutaneous mast cells without a substantial prodegranulating effect. Loratadine is, therefore, a good candidate for clinical testing.

Animals↗
PubMed1997

[Severe syndrome of ovarian hyperstimulation. Incidence, value of criteria of risk factors and preventive methods].

Statistical analysis; square Chi test, Pearson, were practiced, from 1994 to 1996. There were 368 hyperstimulated cycles; three SHOS cases without risk factors and 28 cases with risk factors without SHOS. Risk factors presented were: average seric estradiol 6643.59 +/- 2320 pg/ ml; average follicles: 26.6 +/- 6.9; ovules recuperated by aspiration: 19.32 +/- 9.1. There were five groups according to preventive methods: albumin (13 patients, coasting (one patient); albumin-coasting (11 pacientes); albumin-embryo freezing (3 patients); embryo freezing (one patient). None of the patients presented SHOS.

Analysis of Variance↗
PubMed1996

Skin mast cell releasability in dogs with atopic dermatitis.

Isolated dermal mast cells from atopic dogs are a valuable tool for the analysis of their functional properties in atopic dermatitis. We have characterized the histamine secretory pattern of mast cells enzymatically dispersed from the skin of dogs naturally suffering from this condition. The total histamine content found per isolated skin mast cell was higher in the allergic dogs than in nonatopic (control) animals (8.7 pg/mast cell versus 5.2 pg/mast cell). This phenomenon together with the well known higher concentration of skin mast cell number in atopic dermatitis lesions might account for the observed increase in local histamine concentration (15.0 micrograms/g versus 9.0 micrograms/g). Atopic dog-derived mast cells were highly reactive to both non-immunological (ionophore A23187) and an immunological-like (concanavalin A) stimulus. Furthermore, histamine net release induced by concanavalin A (1 mg/ml) stimulation was clearly enhanced in the atopic dogs (33.3% net release versus 15.4% in controls). These results have not been described in dermal mast cells dispersed from the skin of individuals with atopic dermatitis and clearly support the hypothesis that mast cells play a major role in causing and possibly modulating atopic dermatitis, through enhanced sensitivity or releasability. However, whether these two phenomena are primary abnormalities of atopic dermatitis, or only secondary changes, remains undetermined.

Animals↗