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Biomedical subjects

C Medina

Publications and source records attributed to C Medina.

At least 19 recordsLinked to original sources
PubMed1998

Histone H4 acetylation analyses in patients with polysomy X: implications for the mechanism of X inactivation.

In humans, it is thought that the X-inactivation phenomenon occurs no matter how many X chromosomes are present, and that only one of them remains active. Nevertheless, individuals who have an abnormal number of X chromosomes show a wide spectrum of abnormalities, which increase with the number of X chromosomes present in a given individual. It has been shown that the inactive X chromosome in female mammals is distinguished by a lack of histone H4 acetylation, and that this could be used as an accessible marker for distinguishing between Xi and Xa in spreads of metaphase chromosomes. We studied three X-polysomic patients for the presence of active chromatin by analysis of histone H4 acetylation on unfixed metaphase spreads. Using antisera to H4 acetylated at lysines 16, 8 and 5, respectively, we observed frequencies different from those expected from cells with only one underacetylated X chromosome. In particular, when antiserum to H4 acetylated at lysine 16 was used about 90% of the cells showed acetylation of all X chromosomes. This suggests a possible disturbance in the deacetylation process, probably due to the presence of multiple Xs.

Acetylation↗
PubMed1998

Psychological and spiritual growth in women living with HIV.

Women living with HIV and AIDS face tremendous obstacles to wellness, yet many find ways to use their experience of HIV as a vehicle for psychological and spiritual growth. A qualitative study was conducted to better understand this process. Thirty-four women living with various stages of HIV were interviewed. Five components were found to be important in their psychological and spiritual growth: reckoning with death, life affirmation, creation of meaning, self-affirmation, and redefining relationships. Implications for social work practice and future research are discussed.

Adaptation, Psychological↗
PubMed1998

[Rasmussen syndrome].

INTRODUCTION: Rasmussen's encephalitis is a neurological disorder probably of immunological origin, characterized by intractable epilepsy, neurological deterioration and the presence of antibodies against R3 glutamate receptors. OBJECTIVE: To present the experience of an Argentinian Paediatric Neurology Service during the past 7 years. MATERIAL AND METHODS: We analyzed the clinical histories of 12 patients with RS as defined by the diagnostic criteria proposed by Hart et al. We evaluated the following parameters: neurological examination, neuropsychological assessment, types of crises, age of onset, frequency, distribution, electroencephalogram, video EEG, evoked potentials, neuro-radiological studies; CT and cerebral MR using gadolinium, SPECT, lumbar puncture and cerebral biopsy. RESULTS: The crises were of simple partial motor type in 12 cases, secondarily generalized partial crises in 7 cases, complex partial crises in 4 cases and partial and generalized motor states in 8 cases. RESULTS. The ictal EEGs during the continuous partial crises showed contralateral focal slow activity of the affected side of the body in 30% of cases. The neuro-radiological studies (CT and MR) showed signs of cerebral hemiatrophy in all 12 cases, hyper-intense images in the T2 sequences of the fronto-temporo-parietal regions in 5 cases, an asymmetric megacisterna magna in 1 case and hypoplasia of the cerebellar vermis in another case. CONCLUSIONS: The continuous partial crises showed little correlation with the electro-encephalography. Following administration of i.v. gammaglobulin there was a transient halt in progression of the neurological deterioration and control of the crises in 55% of the cases. Surgery continued to be the treatment recommended for control of the epileptic crises.

Adolescent↗
PubMed1998

[Education of patients with rheumatoid arthritis. Assessment of a survey of interests].

BACKGROUND: The congruence of interests between health care providers and clients is essential if subjects with chronic diseases will be educated. AIM: To assess, in patients with rheumatoid arthritis, those fields in which they would like to receive education. PATIENTS AND METHODS: Eighty eight patients with rheumatoid arthritis were surveyed about the topics in which they would like to be educated. The inquiry included medical aspects, handicap overcoming, social issues and labor aspects. RESULTS: Eighty two percent of patients were interested in medical aspects, 77% in social issues and 71% in handicap overcoming. Eighty three percent of patients with greater handicaps preferred handicap overcoming, 75% social aspects and 74% medical aspects. Younger patients had a greater interest in labor aspects, those with a recently diagnosed disease were interested in their legal rights and those with a prolonged disease wanted information about self help groups. CONCLUSIONS: The greater educational interests of patients with rheumatoid arthritis were on medical aspects. However, those impaired by the disease were interested in handicap overcoming. Age and duration of the disease also influenced the educational interests of patients. Thus, education in these patients must be individualized.

Adult↗
PubMed1998

Influence of the smoking habit in the surgery of inflammatory bowel disease.

UNLABELLED: The smoking habit is a key factor in the development of inflammatory bowel disease (IBD), but little information exists as to the relationship between smoking habit, the need of surgery and its complications. OBJECTIVES: To investigate the relationship between smoking habit, the need of surgery, their complications and clinical recurrence after surgery in Crohn's disease (CD) and ulcerative colitis (UC). METHODS: We studied a group of 62 patients (22 with UC and 40 with CD) with previous surgery. We analyzed the clinical and surgical characteristics of the disease. Smoking habit was established by a personal interview. This group of patients was compared with another control group of 202 patients (133 with UC and 69 with CD) with IBD without previous surgery. RESULTS: Smoking habit was similar between operated and non-operated patients for both UC (73% and 80% non-smokers) and CD (67% and 63% smokers) The number and type of complications after surgery were not related with smoking habit. In CD patients, although the recurrences did not depend on the smoking habit, they did occur earlier in smokers than in non smokers (83.6 +/- 21 vs 155 +/- 50 weeks, p = ns). CONCLUSIONS: The smoking habit does not seem to influence significantly the need of surgery and post surgical development of IBD, although in CD the smokers seems to present recurrence before non smokers.

Adult↗
PubMed1997

Effects of smoking on the presentation and clinical course of inflammatory bowel disease.

OBJECTIVE: To evaluate the influence of regular smoking on the presentation and clinical course of inflammatory bowel disease. METHODS: We performed a case-control study interviewing 160 inflammatory bowel disease patients (63 with Crohn's disease (CD) and 97 with ulcerative colitis (UC)) and 140 first-degree relatives as controls. The risk of developing the disease relative to a smoking habit was calculated as the odds ratio. Furthermore, to evaluate the influence of smoking on the subsequent course of inflammatory bowel disease, we performed a multivariate analysis that included pertinent variables such as the need for surgery, number of hospitalizations and relapses. RESULTS: The pattern of smoking in UC patients was different from that in CD patients. In UC there was a significant predominance of non-smokers and ex-smokers (P = 0.02), whereas smoking habits in CD were not different from those in controls. Giving up smoking was a risk factor to develop UC (odds ratio: 3.2, P = 0.02). In UC, non-smokers and specially ex-smokers need surgery more frequently than smokers (P < 0.01). Otherwise the relapse/year index was not influenced by smoking. In CD there was a non-significant association between smoking habits and the various clinical parameters analysed. UC patients who begin smoking after diagnosis of the disease present a significant reduction in the number of recurrences. CONCLUSION: Smoking habit significantly affects the presentation and clinical course of UC, whereas in CD, a smoking habit does not have any apparent influence on the disease.

Adult↗
PubMed1996

[Juvenile myoclonic epilepsy].

Since juvenile myoclonic epilepsy (EMJ) and/or Janz syndrome is a primary syndrome which persists throughout life, there should be permanent behavioural hygiene and treatment to keep it under control. Suspension of treatment is nearly always followed by recurrence. Although some researchers report relapses of 75% on suspension of treatment, Janz (1995), cited by Dreifuss points out that this rises to 91% in patients who suspend treatment after two years with no crises. This is, to date, the highest documented level of relapses in epilepsy (5,6,12).

Adolescent↗
PubMed1995

Molecular size-fractionation during endocytosis in macrophages.

The sorting of macromolecules within and between membranous organelles is often directed by information contained in protein primary or secondary structure. We show here that absent such structural information, macromolecules internalized by endocytosis in macrophages can be sorted by size. After endocytosis, small solute probes of fluid-phase pinocytosis were recycled to the extracellular medium more efficiently than large solutes. Using macropinosomes pulse labeled with fluorescent dextrans, we examined the ability of organelles to exchange solute contents. Dextran exchange was optimal between organelles of similar age, and small dextrans exchanged more efficiently than large dextrans. Efferent solute movement, from lysosomes or phagolysosomes toward the plasma membrane, occurred through the same endocytic vesicles as afferent movement, toward lysosomes and this movement was solute size dependent. Remarkably, uniform mixtures of different-sized dextrans delivered into lysosomes separated into distinct organelles containing only one dextran or the other. Thus, the dynamics of endosomes and lysosomes were sufficient to segregate macromolecules by size. This intracellular size fractionation could explain how, during antigen presentation, peptides generated by lysosomal proteases recycle selectively from lysosomes to endosomes for association with class II MHC molecules.

Animals↗
PubMed1995

Unexpected familial recurrence of iris coloboma. A delayed mutation mechanism?

Typical isolated ocular coloboma is a congenital abnormality caused by a defective closure of the embryonic fissure of the optic cup. Although an irregular autosomal dominant mechanism of inheritance has been proposed, there is some evidence of other modes of transmission and etiologies. This report shows an unexpected recurrence of iris coloboma, occurring in three sibships of the same family, that could be explained by a "delayed mutation" or "premutation" mechanism.

Child↗
PubMed1994

Parental origin of the extra chromosomes in polysomy X.

Five polymorphic index markers were analyzed by polymerase chain reaction (PCR) to ascertain the parental origin of the extra X chromosomes in seven polysomic cases (one 49,XXXXX, three 49,XXXXY, two 48,XXXY, and one 48,XXYY). All four X chromosomes in 49, X polysomies were maternal in origin and the extra X chromosomes in 48 X polysomies were paternal. In each case the multiple X chromosomes were contributed by a single parent. Taken together with previously reported cases, these data support a single mechanism of sequential nondisjunction during either maternal or paternal gametogenesis as the cause of higher order sex chromosome polysomy.

Adult↗
PubMed1994

A new method for predicting binding affinity in computer-aided drug design.

A new semi-empirical method for calculating free energies of binding from molecular dynamics (MD) simulations is presented. It is based on standard thermodynamic cycles and on a linear approximation of polar and non-polar free energy contributions from the corresponding MD averages. The method is tested on a set of endothiapepsin inhibitors and found to give accurate results both for absolute as well as relative free energies.

Aspartic Acid Endopeptidases↗
PubMed1993

Hydroxychloroquine compared with placebo in rheumatoid arthritis. A randomized controlled trial.

OBJECTIVE: To assess the efficacy of hydroxychloroquine, 400 mg daily, for rheumatoid arthritis. DESIGN: Six-month, double-blind, randomized trial. SETTING: Ambulatory referral clinic in a Mexico City, Mexico, teaching hospital. PATIENTS: A total of 126 patients with early rheumatoid arthritis were randomly assigned to receive hydroxychloroquine, 400 mg/d, or placebo; 121 patients completed the study. RESULTS: Hydroxychloroquine showed a clinically and statistically significant improvement over placebo in joint score (20% greater mean improvement; 10% more patients improved by > 50%); pain (40% greater mean improvement; 19% more patients improved by > 50%); grip strength (22% greater mean improvement; 21% more patients improved by > 50%); patient global assessment (16% more patients stated they had improved); and physician global assessment (12% more patients were judged to have improved). Side effects were mild, and no patients in the hydroxychloroquine group required discontinuation of therapy. Patient compliance with the study medication was high. CONCLUSION: Hydroxychloroquine is moderately effective in early rheumatoid arthritis.

Adult↗
PubMed1993

Membrane-bound sorbitol dehydrogenase in human red blood cells. Studies in normal subjects and in enzyme-deficient subjects with congenital cataracts.

Membrane-bound and soluble forms of erythrocyte sorbitol dehydrogenase (SORD) activity are compared in normal individuals. Both isoenzymes showed similar properties. In a family with red cell SORD deficiency and congenital cataracts, Km values for sorbitol and NAD+ as well as the effect of the enzymatic deficiency on sorbitol accumulation in red cells incubated in high-glucose or high-fructose media were determined. In SORD-deficient patients, the enzymatic deficiency was observed in both crude haemolysate and SORD-M preparations with sorbitol, galactitol, xylitol or ribitol as substrates. The mutation responsible for SORD deficiency did not modify the Km for sorbitol and NAD+. Finally, SORD deficiency produced a significant increase of sorbitol accumulation in red cells incubated in high-concentration glucose media and a significant decrease when the cells were incubated in high-concentration fructose media.

Cataract↗
PubMed1993

A non-hemorrhagic manifestation of vasa previa: a clinicopathologic case report.

BACKGROUND: The rare entity of vasa previa occurs when fetal vessels lying between the amniotic and chorionic membranes cross the cervical os. This report presents a case that was associated with vessel compression and concomitant adverse effects on fetal hemodynamics. CASE: A 23-year-old nulliparous woman at 36 weeks' gestation developed persistent, progressive severe variable decelerations several hours after spontaneous rupture of the membranes, resulting in a decision to perform a cesarean. At delivery, fetal vessels were noted in the membranes near the cervical os, leading into a marginally inserted cord. The decelerations were attributed to compression of the unprotected umbilical arteries by the fetal head. CONCLUSION: Vasa previa often results in fetal death and may be associated with fetal hemorrhage, but lack of bleeding does not exclude the existence of vasa previa. Altered fetal hemodynamics from varying degrees of vessel compression by the presenting part during labor may result in hypoxia and acidosis. A high index of suspicion is necessary to make the diagnosis and institute proper, timely management.

Adult↗
PubMed1992

[Suitability of the practice of recording only the main health problem in primary care].

OBJECTIVE: To analyse if recording only the main health problem (P) can reflect in a valid way the totality of health problems (P+S) cared for and all the actions generated by a consultation. DESIGN: Using a representative sample of the patients seen at the centre over a three-month period, information on P+S was gathered, P was identified and the actions generated by each one of the problems were recorded. Health problems were codified through CIPSAP-2-D and grouping diagnoses. SITE. General Medicine service in a Primary Care Centre. PATIENTS AND OTHERS PARTICIPANTS: All the General Medical physicians at the Centre took part in the study by collecting data on the consultations established by the sampling. MAIN MEASUREMENTS AND RESULTS: Frequency and order among the first 25 P+S and P problems were compared, as was the percentage of secondary problems encountered. Out of 559 consultations examined, Diabetes, Dislepemia and an irritated? Colon stood out as under-represented. Acute infections of the Upper Respiratory Tract, Conjunctivitis and ??Queratitis were over-represented. As for the activity generated, 83.1% corresponded to P, although there was great variability among the problems according to the percentage of secondary problems according to the percentage of secondary problems. CONCLUSIONS: Recording only the main health problem can be a valid instrument for providing an initial view of problems seen.

Evaluation Studies as Topic↗