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Biomedical subjects

M Ramirez

Publications and source records attributed to M Ramirez.

At least 73 records · Page 4Linked to original sources
PubMed1998

A simple and reliable method for hybridization of homothallic wine strains of saccharomyces cerevisiae

A procedure was developed for the hybridization and improvement of homothallic industrial wine yeasts. Killer cycloheximide-sensitive strains were crossed with killer-sensitive cycloheximide-resistant strains to get killer cycloheximide-resistant hybrids, thereby enabling hybrid selection and identification. This procedure also allows backcrossing of spore colonies from the hybrids with parental strains.

Journal Article↗
PubMed1998

Molecular epidemiology of penicillin-resistant Streptococcus pneumoniae isolates recovered in Italy from 1993 to 1996.

Thirty-nine penicillin-resistant Streptococcus pneumoniae isolates recovered among the approximately 700 pneumococcal strains collected from 1993 to 1996 in central and northern Italy were analyzed for several characteristics, including serotype, antibiotic susceptibility profile, chromosomal relatedness (by using pulsed-field gel electrophoresis [PFGE]), restriction fragment length polymorphism (RFLP) of the penicillin-binding protein (PBP) genes 1A, 2X, and 2B, and the presence of a variety of antibiotic resistance genes (determined by hybridization with appropriate DNA probes). The MICs of penicillin for most of the isolates (30 of 39) were high, in the range of 1 microgram/ml or higher, and these 30 isolates carried additional resistance traits to two or more drugs (erythromycin, chloramphenicol, co-trimoxazole, and tetracycline) and expressed serotypes 9, 19, and 23 and three distinct PFGE patterns. More than half (22 of 30) of the isolates for which MICs were high were identified as representatives of two widespread international epidemic clones of S. pneumoniae. The first one of these clones (seven isolates) expressed serotype 23F and possessed all properties characteristic of the widespread Spanish/USA international clone. Seven additional strains with serotype 19 also had the same PFGE pattern, PBP gene, and RFLP polymorphisms, and other properties typical of the serotype 23 Spanish/USA clone, suggesting that these strains were the products of a capsular transformation event (from serotype 23F to serotype 19) in which the Spanish/USA clone was the recipient. The second international clone was represented by eight serotype 9 isolates which were resistant to penicillin and trimethoprim-sulfamethoxazole and had the molecular properties of the French/Spanish epidemic clone. The remaining eight isolates for which penicillin MICs were high appeared to represent a hitherto-undescribed "Italian" clone; they had a novel PFGE type, unique RFLPs for the PBP genes, and resistance to tetracycline, trimethoprim-sulfamethoxazole, and erythromycin, and the penicillin MICs for these isolates were 2 to 4 microgram/ml.

Chromosome Mapping↗
PubMed1998

Antioxidant supplementation and respiratory functions among workers exposed to high levels of ozone.

Ozone exposure has been related to adverse respiratory effects, in particular to lung function decrements. Antioxidant vitamins are free-radical scavengers and could have a protective effect against photo-oxidant exposure. To evaluate whether acute effects of ozone on lung functions could be attenuated by antioxidant vitamin supplementation, we conducted a randomized trial using a double-blind crossover design. Street workers (n = 47) of Mexico City were randomly assigned to take daily a supplement (75 mg vitamin E, 650 mg vitamin C, 15 mg beta carotene) or a placebo and were followed from March to August 1996. Pulmonary function tests were done twice a week at the end of the workday. During the follow-up, the mean 1-h maximum ozone level was 123 ppb (SD = 40). During the first phase, ozone levels were inversely associated with FVC (beta = -1.60 ml/ppb), FEV1 (beta = -2.11 ml/ppb), and FEF25-75 (beta = -4.92 ml/ppb) (p < 0.05) in the placebo group but not in the supplement group. The difference between the two groups was significant for FVC, FEV1, and FEF25-75 (p < 0.01). During the second phase, similar results were observed, but the lung function decrements in the placebo group were smaller, suggesting that the supplementation may have had a residual protective effect on the lung. These results need to be confirmed in larger supplementation studies.

Adolescent↗
PubMed1998

Biology of CD34+CD38- cells in lymphohematopoiesis.

Since the discovery of the CD34 stem/progenitor cell antigen, considerable progress has been made in further purifying human lymphohematopoietic stem cells (HSC). These studies have identified a number of antigens which can be targeted to subfractionate the CD34+ cell population. In particular, several lines of evidence suggest that the rare CD38(-)subpopulation of CD34+ cells may be enriched in HSC. This review briefly summarizes relevant knowledge concerning the CD38 molecule and the results of in vitro and in vivo studies of CD34+38(-)cells. Possible clinical uses for purified CD34+38(-)cells are outlined.

ADP-ribosyl Cyclase↗
PubMed1997

Clinical relevance of T-cell receptor delta gene rearrangements in childhood B-precursor cell acute lymphoblastic leukaemia.

The large majority of childhood B-precursor cell acute lymphoblastic leukaemia cases present IgH and TCRdelta gene rearrangements. These rearrangements have been widely used as specific markers for monitoring minimal residual disease. However, their prognostic value still remains unclear. In order to determine whether IgH and TCRdelta gene rearrangements have any influence on relapse and event-free survival (EFS), we analysed the clinical impact of these genetic characteristics in 51 B-precursor acute lymphoblastic leukaemia patients. 46/51 patients (90.2%) showed IgH gene rearrangements by Southern blot and/or polymerase chain reaction (PCR) analysis. No statistically significant associations were found between IgH gene rearrangement pattern and age, sex, WBC count, immunophenotype, risk factor, relapse or EFS. 27/41 patients (66%) showed Vdelta2Ddelta3 recombination by Southern blot and/or PCR analysis. At a median follow-up of 53 months the estimated 5-year EFS probability was 78 +/- 3% for the whole group. The EFS probability among patients with a Vdelta2Ddelta3 recombination pattern in the TCRdelta locus was 90 +/- 3%, whereas for patients without Vdelta2Ddelta3 recombination was 39 +/- 13% (P < 0.005). IgH rearrangement patterns do not appear to influence relapse or EFS probability. However, TCRdelta gene rearrangement patterns have a relevant impact on the relapse rate and the EFS probability. Patients with Vdelta2Ddelta3 recombination have better clinical outcome than patients without this recombination, independent of any other prognostic factors.

Adolescent↗
PubMed1997

Ubiquitous distribution of the competence related genes comA and comC among isolates of Streptococcus pneumoniae.

DNA probes specific for the pneumococcal competence regulatory genes comA and comC were used to test the presence of these genes in 214 pneumococcal isolates selected to represent a wide variety of clonal types and genetic backgrounds (as defined by chromosomal macrorestriction patterns and multilocus enzyme analysis), a variety of serotypes, isolation dates (between 1916 and 1996), geographic origins (on four continents), as well as different clinical origins (including both infection sites and colonization sites). Each isolate gave positive signal with both DNA probes. The comA and comC genes were never on the same SmaI restriction fragment and the comA gene showed a considerable degree of polymorphism from one strain to another. While DNA sequencing of 50 of the isolates have identified three distinct alleles of the comC gene, the number of mutations within the leader peptide were minimal. The results suggest that the mechanism to undergo genetic transformation is widespread within the species of Streptococcus pneumoniae.

Alleles↗
PubMed1997

Predictors of becoming redomiciled among older homeless women.

The authors test a model to predict residential outcome among 201 homeless women aged 50 and over. On two-year follow-up, 47% were successfully domiciled. Of 12 variables examined using logistic regression analysis, only 2 variables, perceived support and number of community facilities attended were significant predictors of being domiciled on follow-up. Three additional variables-absence of psychosis, a lifetime history of less than one year of homelessness, and number of entitlements-attained near-significance. Although residential outcome is predicted by a few individual characteristics, what is most striking is the lack of suitable housing options.

Female↗
PubMed1997

Prevalence of behavior disorder and disturbance to family and staff in a sample of adult day health care clients.

Latent class-derived prevalence estimates of behavior disorder are provided for adult day health care (ADHC) clients; informal and formal caregivers reported 11% and 14%, respectively, of these clients as engaging in severe disturbed behavior (95% confidence intervals across sources are from 7% to 18%). The prevalences, estimated for informal and formal caregivers respectively, were 12% and 16% for affective disorder, 15% and 18% for cognitive disorders, 16% and 13% for verbal-vocal agitation, and 6% and 8% for socially inappropriate behavior. These rates can be contrasted with those of the institutional population which, while higher, overlap with the distribution of behavior disorder for ADHC community residents. The degree of reported disturbance to family and staff was similar across items.

Adult↗
PubMed1996

Cisapride reduces postoperative gastrocaecal transit time after cardiac surgery in children.

OBJECTIVE: To investigate the influence of the prokinetic drug cisapride on gastrocaecal transit time (GCTT) in children after open heart surgery. DESIGN: Prospective, randomized and controlled study. SETTING: Interdisciplinary paediatric intensive care unit in a tertiary-care children's hospital. PATIENT: Twenty-one children with a median age of 6.2 years on day 1 after uncomplicated open heart surgery for isolated septal defects, acquired mitral or aortic valve disease or tetralogy of Fallot. Control group consisting of 10 healthy children with a median age of 8.1 years. INTERVENTIONS: Ten children were randomized to receive cisapride 0.2 mg/kg body weight, 30 min prior to measurement of GCTT. MEASUREMENTS AND RESULTS: GCTT was measured using hydrogen breath testing with a test solution containing lactulose and mannitol (0.4 g/kg and 0.1 g/kg body weight respectively). GCTT was markedly delayed in all patients compared to the control group. Within 8 h 8/10 patients in the treatment group versus 4/11 patients in the non-cisapride group achieved gastrocaecal transit. No adverse side-effects were observed. CONCLUSIONS: Cisapride accelerates gastrocaecal transit after open heart surgery in children. In intensive care patients on inotropic support or opioid medication, it may facilitate the earlier reintroduction of enteral feeding.

Breath Tests↗
PubMed1996

The renin-angiotensin system in the rabbit eye.

We analyzed the components of the renin-angiotensin system (RAS) in ocular tissues of normal rabbit eyes and compared the results with those measured in rabbit eyes with proliferative vitreoretinopathy and ocular hypertension. Proliferative vitreoretinopathy was induced by injection of human platelets into the vitreous humor, and ocular hypertension was induced by injection of alpha-chymotrypsin into the posterior chamber. Angiotensinogen, renin, angiotensin converting enzyme (ACE), angiotensin II (Ang II), and Ang II receptors were assessed using conventional biochemical techniques. The vascularized tissues of normal eyes contained high renin and ACE activities concomitant with low concentration of angiotensinogen and Ang II. In general, in the ocular humors, the opposite was found. The Ang II receptor density was highest in the uveal tract [range 35-190 fmol/mg protein]. The AT1 receptor subtype predominated [> 80%]. The RAS was only minimally different in the two pathological models except that, in ocular hypertension, the renin activity in the uveal tract was reduced [-50%]. Also, the ratio of AT1 to AT2 receptors changed as compared to control, although the total receptor density remained unaltered. In conclusion, we present evidence for the presence of a complete local RAS in the rabbit eye, which is only marginally affected by the two pathological models studied.

Angiotensin II↗
PubMed1996

Immunohistochemical localization of the glucocorticoid receptor in human fetal membranes and decidua at term and preterm delivery.

The human fetal membranes and decidua may be important in the onset and/or progression of human labor by providing prostaglandins for this process. Glucocorticoids have been implicated in the regulation of prostaglandin production by these tissues but to date there is no direct evidence for glucocorticoid receptors (GRs) being present in human intrauterine tissues. The purpose of the present study was to determine, using immunohistochemistry, whether the human fetal membranes and decidua contained GRs; to determine the localization of receptors to the cytoplasm or nuclei, and to examine the content and distribution of the GRs in tissues obtained during pregnancy following preterm labor (< 37 weeks) and at term prior to and following term labor. Term tissues were obtained prior to labor by elective Caesarean section (n = 9) or following vaginal delivery (n = 9). Tissues from 14 patients who delivered preterm but with no clinical evidence of infection were also examined. Cryostat sections were thaw-mounted onto microscope slides. The immunoreactive GRs were visualized with an Elite Vectastain ABC Kit using a polyclonal antibody prepared against a synthetic peptide corresponding to amino acids 346-367 of the human GR. At term, nuclear GRs were found in amnion epithelial cells, mesenchyme and the chorion laeve. GRs were present, but were less defined, in the decidua. A similar distribution was found in the preterm tissues. However, nuclear staining in the amnion epithelial cells, mesenchymal cells, chorion and decidua was more pronounced in tissues obtained following preterm labor. This study provides direct evidence for the presence of GRs in human fetal membranes and decidua, and suggests the possible importance of multiple cell types in the action of glucocorticoids in these tissues.

Amnion↗
PubMed1996

Determination of pantothenic acid in infant milk formulas by high performance liquid chromatography.

A reverse-phase liquid chromatographic method was adapted for the assay of pantothenic acid in infant milk formulas. Sample preparation consisted of deproteination with acetic acid and sodium acetate solutions, followed by centrifugation and filtration. The chromatographic system included a C-18 column and a mobile phase consisting of a sodium phosphate buffer and acetonitrile (97:3, vol/vol). The column effluent was monitored by UV detection at 197 nm. The system was linear from 50 to 800 ng. The recoveries of pantothenic acid from augmented samples ranged from 89 to 98%, and the coefficients of variation ranged from 1.17 to 3.20%. The results obtained with the HPLC and a microbiological method were highly correlated for starting infant formula, follow-up infant formula, and formula for infants of low birth weight from four different manufactures. All formulas analyzed contained pantothenic acid at concentrations higher than those declared on their nutritional labels and were in compliance with international recommendations.

Chromatography, High Pressure Liquid↗
PubMed1996

Non-tunneled catheters in children undergoing bone marrow transplantation.

We analyzed the use of non-tunneled (polyurethane double lumen) central venous catheters (CVCs) in 62 children undergoing bone marrow transplantation. The catheters were inserted in the Critical Care Unit without surgery or general anesthesia. The complications were pneumothorax in two patients and hemopneumothorax in two other patients (6.06%), entry site infection in six patients (9.6%), catheter-related infection in eight patients (12.9%) and catheter-related sepsis in nine patients (14.5%). The catheters were removed upon completion of therapy in 46 patients (74.1%), death in seven patients (11.3%) and in nine cases (14.5%) for infection. Despite the complications specific to non-tunneled catheter insertion, we believe this is indicated for patients during conditioning, transplantation and immediate post-transplantation periods.

Adolescent↗
PubMed1996

Study of chimerism in long-term survivors after bone marrow transplantation for severe acquired aplastic anemia.

Chimerism studies employing PCR and Southern techniques targeting VNTR loci were performed in 17 severe acquired aplastic anemia patients who were long-term survivors after BMT. They were studied a median of 4 years after BMT (1-12). All patients had normal blood counts. All patients conditioned with radiation-based schemes showed a full donor pattern of hemopoiesis. Conversely, out of five patients who received only cyclophosphamide as conditioning therapy, two of them had a late graft failure (2.4 and 3 years after BMT). One of these relapsing patients had a durable mixed chimerism, which was first detected 1 month after BMT. Our results seem to suggest that durable mixed chimerism can antecede graft failure in some patients conditioned only with cyclophosphamide, and that a more stringent monitoring can be clinically rewarding in this group of patients.

Adolescent↗
PubMed1996

Pediatric experience with autologous peripheral blood progenitor cell transplantation: influence of CD34+ cell dose in engraftment kinetics.

The aim of this study was to analyze factors affecting mobilization and engraftment in 40 children undergoing autologous peripheral blood progenitor cell transplantation for different malignancies: 19 patients with haematological malignancies and 21 patients with solid tumors. Patients received 4-5 days of rhG-CSF (12 micrograms/kg/day) subcutaneously. Apheresis was performed by continuous flow blood cell separation beginning on the fifth day of rhG-CSF. For patients weighing < or = 25 kg, the extracorporeal line was primed with irradiated red blood cells. After myeloablative conditioning regimens, patients were grafted with 7.21 +/- 7.8 x 10(6)/kg CD34+ cells. Days to achieve an absolute neutrophil count > 0.5 x 10(9)/1 and a platelet count > 20 x 10(9)/1 without platelet support were 9.50 +/- 1.2 (range 7-13) and 18.1 +/- 8.3 (range 9-37), respectively. The number of CD34+ cells infused was highly correlated with engraftment kinetics (P = 0.0001). The patient's body weight and the number of previous chemotherapy courses had a negative influence on CD34+ cells collected.

Adolescent↗