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Biomedical subjects

M García

Publications and source records attributed to M García.

At least 271 records · Page 15Linked to original sources
PubMed1991

Computer program for the kinetic equations of enzyme reactions. The case in which more than one enzyme species is present at the onset of the reaction.

This paper presents an extension of the program developed by Varón, Havsteen, García, García-Cánovas & Tudela [(1990) Biochem. J. 270, 825-828] for the expression of the transient-phase and steady-state kinetic equations of a general enzyme system in which the only enzyme species present at the onset of the reaction is the free enzyme. The program has been extended to situations in which more than one enzyme species may be present at the onset of the reaction. The program is given in Supplementary Publication SUP50165 (5 pages), which has been deposited at the British Library Document Supply Centre, Boston Spa, Wetherby, West Yorkshire LS23 7BQ, U.K., from whom copies can be obtained on the terms indicated in Biochem. J. (1991) 273, 5.

Computer Simulation↗
PubMed1991

Acrolein genotoxicity in Drosophila melanogaster. I. Somatic and germinal mutagenesis under proficient repair conditions.

The genotoxicity of acrolein in D. melanogaster was investigated using 2 different SMART assays, the eye spot and wing spot tests, and 2 germinal tests, the sex-linked recessive lethal (SLRLT) and sex chromosome loss (SCLT) tests. For the 2 latter, exposure by feeding as well as injection was used. The results indicate that: (i) acrolein is mutagenic in the SLRLT when injected but not when fed; (ii) the SCLT did not reveal clastogenic effects; (iii) acrolein had genotoxic effects in both SMART assays; (iv) we also had several indications that acrolein is metabolized into a second genotoxic product.

Acrolein↗
PubMed1991

PASHEMOS: a versatile program written in Pascal to simulate patterns on the shells of molluscs, according to the Meinhardt model.

In this paper we describe PASHEMOS, a user-friendly program written in Pascal to solve the Meinhardt-Klingler model numerically. This model studies the shell pattern pigmentation of molluscs. Moreover, PASHEMOS enables theoretical analysis to be performed on the different steady states. The program takes into account the four differential equation systems established in the model. It numerically solves these systems. This program is developed in such a way that both the equation system type and the parameter values can be chosen. The pattern is displayed in each case, and other output possibilities are available (i.e. three-dimensional concentration plotting, phase plane, phase space, stability analysis). The implementation of the program for the case of a three-variable system is shown as an example of PASHEMOS handling. Program applications for other models are also discussed.

Algorithms↗
PubMed1991

[Harvesting of mononuclear cells from peripheral blood in malignant hemopathies].

After demonstrating through animal models that progenitor cells with haemopoietic regenerative capability are present in peripheral blood, such precursor cells were also found in the mononucleated cell (MNC) fraction of human peripheral blood. It was shown that such cells increase in the recuperative period following chemotherapy. A number of studies have demonstrated that autologous infusion of such MNC achieved by cytapheresis may lead to a quick restoration of haemopoiesis. The initial results of peripheral blood MNC achievement in 18 patients with different malignancies of the blood are presented in this paper. Ninety-one cytapheresis sessions were carried out, 88 with a Fenwall CS-3000 continuous-flow machine, and the remaining three with a Haemonetics V-50 discontinuous-flow cell separator. The number of sessions per patient ranged from three to six and the harvested MNC count was 19.3 x 10(9)/L, the percentage of recovery being 56.4%. Some studies are currently in course aimed to analyse the MNC subpopulations in order to measure the progenitor-cell fraction and to establish the viability of such cells for further transplants. Since only five patients have recently been transplanted, all successfully, no definite conclusions can be drawn presently in this connection.

Adolescent↗
PubMed1991

[Endoscopic choledochoduodenostomy in the treatment of impacted calculi in Vater's papilla].

In a series of 204 patients with common duct stones, sphincterotomy was not possible in 10, due to an impacted stone in the papilla. An endoscopic choledocho-duodenostomy was performed which was effective in all cases. One patient suffered a retroperitoneal perforation which was managed medically. This technique is an effective alternative to sphincterotomy in the treatment of impacted papillary stones. Retroperitoneal perforation is a major risk to be taken into account.

Aged↗
PubMed1991

[Culture of cells forming granulomonocytic colonies in bone marrow (GM-CFU) in myelodysplastic syndromes and their relation to hematological findings and FAB subtype].

The results of "in vitro" culture of granulomonocytic precursor cells (CFU-GM) of the bone marrow from 44 patients were analysed in the present work. The correlation with the patient's haematological characteristics, their FAB subtypes (i.e., 6 cases of refractory anaemia (RA), 11 of acquired sideroblastic anaemia (ASA), 15 cases of refractory anaemia with excess blasts (RAEB), 5 cases of RAEB in transformation (RAEBT) and 7 cases of chronic myelomonocytic leukaemia (CMML), and the survival were examined as well. The technique used for cell culture was that of Pike and Robinson, following the classification proposed by Florensa for estimating the growth patterns. Anomalies of the myeloid clonal proliferation were found in 81% of the cases. There was direct correlation between the number of aggregates and the polymorphonuclear cell count, whereas the highest number of blast cells coincided with increased number of clusters in cultures. CNNL showed the highest aggregate counts. The B growth pattern (both colony and aggregate growth) was most frequently seen in CMML; pattern C2 (decreased colonies with increased aggregate count) appeared in RAEB, RAEBT and CMML, and pattern C3 (decrease of both colony and aggregate counts) was found only in RA and ASA. None of the culture findings appreciably associated with the survival.

Aged↗
PubMed1991

[Intestinal Microspora infections in a patient with acquired immunodeficiency syndrome].

A 24 year old man with AIDS diagnosed in 1989 and a history of several episodes of pulmonary pneumocystosis developed chronic diarrhea and severe epigastric pain. Endoscopy revealed a granular intestinal mucosa. There was atrophy of villi and Giemsa, Ziehl-Nielsen and Gram staining identified 1.5 to 2 u spores in the cytoplasm of intestinal cells. Transmission electron microscopy of the spores revealed a thick wall, a sporoplasm with a nucleus, ribosomes, a posterior vacuole and a polar filament with multiple coils; no mitochondria were seen. Thus, the patient had intestinal microsporidiosis caused by Enterocytozoon bieneusi. This is a rare pathogen recently identified in man.

AIDS-Related Opportunistic Infections↗
PubMed1991

[Evaluation of 2 culture systems for the isolation of opportunistic mycobacteria].

The increment of infections produced by opportunist environmental mycobacteria (OEM) raises the question about the appropriateness of the conventional culture methods since they were initially designed to isolate M. tuberculosis. In this study we have comparatively evaluated the yield of a conventional culture (Löwenstein-Jensen) with respect to that of Middlebrook 7H12 (Bactec) in 396 selected samples in which OEM were isolated. Samples with commensal flora were previously subjected to a chemical homogenization-decontamination process with alkaline N-acetyl-cysteine. All cultures were sown with standard inoculates obtained from centrifugate material. The 7H12 culture showed a more rapid detection (mean: 17-18 days) and a greater effectiveness in the isolation of eventually pathogenic mycobacteria than the conventional Löwenstein-Jensen culture. The 7H12/LJ ratio for the species with high clinical relevance was: 1.3 for M. kansasii, 1.0 for M. marinum, 1.8 for M. scrofulaceum, 1.3 for M. xenopi, 1.5 for M. avium-intracellulare, 0.5 for M. chelonae, and 2.0 for M. fortuitum.

Bacteriological Techniques↗
PubMed1991

[Keratitis caused by Pseudomonas aeruginosa and secondary endophthalmitis].

We report three patients with Pseudomonas aeruginosa keratitis. Two patients in the Intense Care Unit had exogenous bacterial endophthalmitis assessed by histopathology; the infection had probably a nosocomial origin and the outcome was fatal. The third case was associated with the use of soft contact lenses and even though clinically endophthalmitis was suspected there was a favourable response to treatment. We review diagnostic aspects and discuss the management of bacterial keratitis and endophthalmitis.

Adult↗
PubMed1991

[Some factors that influence acceptance of antimalarial chemoprophylaxis in groups exposed to infection].

1,100 internationalist workers were surveyed in order to assess the factors bearing upon the proper use of antimalarial chemoprophylaxis in endemic areas of Africa. We detected difficulties concerning advisin and its quality. Most subjects did not begin chemoprophylaxis before leaving Cuba, according to the advice. It was proved that one third of them do not observe regularly this prophylactic measure.

Africa↗
PubMed1990

Computer program for the expression of the kinetic equations of enzyme reactions as functions of the rate constants and the initial concentrations.

A versatile computer program with an easy input method has been developed for the construction of the terms in kinetic equations of enzyme reactions. It allows the expression of the time-dependence of the concentrations of all of the species involved as functions of the kinetic parameters. The mathematical theory used in this paper, the program and examples of its use have been deposited as Supplementary Publication SUP 50159 (41 pages) at the British Library Document Supply Centre, Boston Spa, Wetherby, West Yorkshire LS23 7BQ, U.K., from whom copies can be obtained on the terms indicated in Biochem. J. (1990) 265, 5.

Enzymes↗
PubMed1990

Kinetics of the trypsinogen activation by enterokinase and trypsin.

A global kinetic analysis of the mechanisms of the trypsinogen activation by enterokinase and trypsin is presented. The kinetic equations of both the transient-phase and the steady-state of these mechanisms are presented. In addition, we here derive the corresponding kinetic equations for the case in which the condition of rapid equilibrium prevails and we propose a kinetic data analysis. The significance of this approach to the treatment of other zymogen activation processes is discussed.

Animals↗
PubMed1990

Trisomy 13 syndrome and neural tube defects.

Abnormalities of the CNS, such as arhinencephaly or holoprosencephaly, are common findings in trisomy 13 syndrome. However, neural tube defects (NTDs) are rarely reported. A review of 267 patients in the literature on reported CNS developmental defects in trisomy 13 syndrome showed only 6 patients with lumbosacral NTDs. No case of encephalocele or anencephaly was found. We report on 3 patients with spina bifida from the records of 34 necropsies of karyotyped trisomy 13 syndrome, which were found among 403,710 births.

Abnormalities, Multiple↗
PubMed1990

Evolution of the Simiiformes and the phylogeny of human chromosomes.

This paper is based on the results of Primate chromosome studies obtained using high resolution techniques in our and other laboratories. We discuss the origin and the evolution of the chromosomes in the human karyotype and the time in evolution of the Simiiformes when they acquired their present morphology. Our results indicate that the chromosomes that underwent a higher number of reorganizations during the evolution of the Simiiformes coincide with the chromosomes most often implicated in human chromosome pathology. We describe the main reorganizations that took place during Primate evolution. Centromere activation and inactivation and heterochromatin changes are discussed as mechanisms of chromosome evolution.

Animals↗
PubMed1990

[The risk factors of invasive carcinoma of the cervix uteri in Latin America].

A study of 759 patients with invasive cervical cancer, 1,430 controls, and 689 sexual partners of the participants who declared that they were monogamous was conducted in Colombia, Costa Rica, Mexico, and Panama from January 1986 to June 1987, to evaluate the risk factors associated with this neoplasm. The principal risk factors identified were: initiation of sexual relations by the woman at an early age, number of stable sexual partners (relationships of more than three months' duration), number of liveborn children, presence of DNA from human papilloma virus (HPV) types 16 or 18, history of venereal disease, lack of exposure to early detection programs, deprived socioeconomic conditions, and number of sexual partners of the partners of the monogamous women. Smoking increased the risk in those women who were shown to have DNA from HPV types 16 or 18. Fifty percent of the patients and 29% of the controls said they had never had a cytological examination (Papanicolaou test). No association was observed between the presence of HPV and sexual behavior. The study showed the need for further research on the possible mechanisms involved in carcinogenesis and infection. The common denominators of the risk factors mentioned are underdevelopment and poverty, which affect broad sectors of these populations. Mass detection programs targeting high-risk groups can reduce the high incidence of cervical cancer in Latin America.

Age Factors↗
PubMed1990

Risk factors for invasive carcinoma of the uterine cervix in Latin America.

A study of 759 cervical cancer patients, 1,430 controls, and 689 sex partners in four Latin American countries has made it possible to assess the influence of multiple factors upon the risk of invasive cervical cancer. The principal risk factors identified were the woman's age at first coitus, the number of her steady sex partners, her number of live births, the presence of DNA from human papillomavirus (HPV) types 16 or 18, a history of venereal disease, nonparticipation in early detection programs, and low socioeconomic status. There is good reason to believe that extensive detection programs directed mainly at high-risk groups in the Americas can reduce the high incidence of cervical cancer in this Region.

Adult↗