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Biomedical subjects

M Alvarez

Publications and source records attributed to M Alvarez.

At least 217 records · Page 12Linked to original sources
PubMed1996

Safety and efficacy of the laryngeal mask airway. A prospective survey of 1400 children.

A survey of laryngeal mask airway usage in 1400 infants and children by ten trainee anaesthetists was undertaken to provide information about insertion and complication rates using the standard insertion technique and a limited range of standardised anaesthetic techniques. Placement was successful in 90% (1258/1400) at the first attempt, 8% (112/1400) at the second attempt and 2% (29/1400) required an alternative technique of insertion. One patient vomited during insertion and the procedure was abandoned, but aspiration did not occur. The overall problem rate was 11.5% and there were significantly more problems during induction of anaesthesia (p < 0.02). Oxygen saturation decreased below 90% briefly on 23 occasions (1.7%). The incidence of problems was unrelated to the mode of ventilation, or whether isoflurane or total intravenous anaesthesia with propofol was used for maintenance. Most problems came with use of the size 1 laryngeal mask (p < 0.001). The subspecialty with the highest problem rate was ear, nose and throat surgery (p < 0.001). There was a significant decrease in problems with increasing experience (p < 0.001). There was no major morbidity associated with use of the device. We conclude that the laryngeal mask provides a safe and effective form of airway management for infants and children in the hands of supervised anaesthesia trainees both for spontaneous and controlled ventilation using either isoflurane or total intravenous anaesthesia.

Adolescent↗
PubMed1996

HLA DR and DQ polymorphism in Ashkenazi and non-Ashkenazi Jews: comparison with other Mediterraneans.

HLA-DR and DQ alleles have been detected by DNA typing in Ashkenazi and non-Ashkenazi Jews from Israel. Allele frequencies, characteristic DR/DQ linkage disequilibria, population distances and their corresponding dendrogram by using the Neighbor-Joining method were used to study relatedness between Jewish and other Mediterranean and non Mediterranean populations. Closest relatedness is observed between Ashkenazi and non-Ashkenazi Jews, and, in decreasing order, also with Algerians, Spaniards (including Spanish-Basques), French and Italians. Also, particular characteristic Central European alleles are observed in Ashkenazi Jews and Mediterranean/African alleles in non-Ashkenazi Jews. This is consistent with historical data, Jews being an ancient Mediterranean population, who have had a certain degree of admixture with their 2000-3000 years old neighbors in spite of cultural and religious traditions which have preserved identity outside Israel.

Algeria↗
PubMed1996

Thyroid hormone and attention in school-age children with congenital hypothyroidism.

The relationship between attention and thyroid hormone was examined using a retrospective database of 85 7-year-old children with congenital hypothyroidism who received psychological evaluations and thyroid function tests on the same day. Four unique subgroups with different levels of thyroxine and thyrotropin were compared on psychological tasks and measures of attention. Children with high levels of both hormones were found to be significantly more distractable on an index of cognitive attention but were reportedly less hyperactive. Level of thyroxine accounted for over 10% of the variance in attention.

Attention↗
PubMed1996

Infant fussing and crying patterns in the first year in an urban community in Denmark.

Infant crying amounts and patterns in 590 1- to 12-month-old infants in an urban community in Denmark were studied using the Crying Patterns Questionnaire. The impact of the crying on parents and the primary health services was also assessed. The results showed that Danish mothers leave their infants to "cry out" substantially less than mothers in the UK and North America. Despite this difference, mean crying amounts, crying patterns and the incidence of persistent crying were similar to those reported in earlier western studies. The findings support the view that the infant crying peak in the first 3 months is due to normal maturational and developmental processes.

Age Factors↗
PubMed1996

Late juvenile metachromatic leukodystrophy treated with bone marrow transplantation; a 4-year follow-up study.

We treated a 28-year-old woman who had metachromatic leukodystrophy with bone marrow transplantation. Leukocyte arylsulfatase A levels increased to the donor's range after successful graft. Motor and sensory nerve conduction values did not change significantly in the 4 years after the transplant, and subcortical white matter lesions, as shown on MRI, remained stable during that period of time. The results, after 4 years of follow-up, indicate that the disease has not progressed and signs and symptoms are stabilized.

Adult↗
PubMed1996

Clinical Reversal of Multidrug Resistance.

Reversal of drug resistance offers the hope of increasing the efficacy of conventional chemotherapy. We tested dexverapamil as a P-glycoprotein antagonist in combination with EPOCH chemotherapy in refractory non-Hodgkin's lymphoma. In a cross-over design, dexverapamil was added to EPOCH after disease stabilization or progression occurred. Objective responses were observed in 10 of 41 assessable patients. Biopsies for mdr-1 were obtained before EPOCH treatment and at the time of cross-over to dexverapamil. Levels of mdr-1 were low before EPOCH, but increased fourfold or more in 42% of patients in whom serial samples were obtained. Pharmacokinetic analysis revealed median peak concentrations of dexverapamil and its metabolite, nor-dexverapamil, of 1.66 µmol/l and 1.58 µmol/l, respectively. Since both are comparable antagonists, a median peak total reversing concentration of 3.24 µmol/l was achieved. Pharmacokinetic analysis of doxorubicin and etoposide levels confirmed a delay in the clearance of doxorubicin ranging from 5% to 24%; no change in the pharmacokinetics of etoposide was observed. This study provides sufficient rationale for testing dexverapamil in a randomized clinical trial.

Journal Article↗
PubMed1996

One-session management of cervical intraepithelial neoplasia: a solution for developing countries.

Six hundred thirty-nine patients with CIN on referral Pap were evaluated cytocolposcopically at the first visit and decided whether to be treated the same day or not. One hundred ninety-two patients (30%) were considered negative. Follow-up evidenced later appearance of CIN in five of them. One hundred fifty-three (24%) were candidates for delayed treatment due to conditions contraindicating same-day treatment. Two hundred ninety-four patients (46%) were randomly allocated in LEEP (149) or excisional laser (145) arms, and treated the same day under local anesthesia. Both arms were comparable. There were three microinvasive carcinomas diagnosed in the surgical specimen. LEEP was faster and produced less bleeding than laser, although required a mean of four slices to remove the lesion. Arterial hypertension after anesthetic infiltration was detected in 26% of cases. Two intraoperative and two delayed bleeders required surgery. The size of lesion and surgical defect were larger than those reported in the literature. Margins were involved in 8 patients (2.7%). Only 4.7% (7/149) of patients randomized to LEEP and 3.4% (5/145) with excisional laser had persistent or recurrent CIN on follow-up. Factors predisposing to failure included depth of surgical defect, grade of lesion, and operator's expertise. With this approach, 69% of patients referred for cytology of CIN were adequately managed in the first visit, which contrasts to classical management that reaches the state of treatment in 30% of patients. LEEP appears to be faster, less costly, and requires less expertise. Its use in conjunction with adequate screening is recommended for developing countries.

Conization↗
PubMed1996

One-Session Management of Cervical Intraepithelial Neoplasia: A Solution for Developing Countries. A Prospective, Randomized Trial of LEEP versus Laser Excisional Conization

Six hundred thirty-nine patients with CIN on referral Pap were evaluated cytocolposcopically at the first visit and decided whether to be treated the same day or not. One hundred ninety-two patients (30%) were considered negative. Follow-up evidenced later appearance of CIN in five of them. One hundred fifty-three (24%) were candidates for delayed treatment due to conditions contraindicating same-day treatment. Two hundred ninety-four patients (46%) were randomly allocated in LEEP (149) or excisional laser (145) arms, and treated the same day under local anesthesia. Both arms were comparable. There were three microinvasive carcinomas diagnosed in the surgical specimen. LEEP was faster and produced less bleeding than laser, although required a mean of four slices to remove the lesion. Arterial hypertension after anesthetic infiltration was detected in 26% of cases. Two intraoperative and two delayed bleeders required surgery. The size of lesion and surgical defect were larger than those reported in the literature. Margins were involved in 8 patients (2.7%). Only 4.7% (7/149) of patients randomized to LEEP and 3.4% (5/145) with excisional laser had persistent or recurrent CIN on follow-up. Factors predisposing to failure included depth of surgical defect, grade of lesion, and operator's expertise. With this approach, 69% of patients referred for cytology of CIN were adequately managed in the first visit, which contrasts to classical management that reaches the state of treatment in 30% of patients. LEEP appears to be faster, less costly, and requires less expertise. Its use in conjunction with adequate screening is recommended for developing countries.

Journal Article↗
PubMed1996

[Dengue in Nicaragua, 1994: reintroduction of serotype 3 in the Americas].

The principal aim of this work was to report the reintroduction of dengue virus serotype 3 in the Americas after an absence of 17 years. In addition, it describes the most common symptoms associated with classical dengue and hemorrhagic dengue and presents data on the distribution of the epidemic in the various comprehensive local health care systems of Nicaragua. The study group consisted of 39 patients hospitalized in Managua and León for dengue with hemorrhagic manifestations and hemorrhagic dengue. Of these patients, 34 were classified as probable or confirmed cases of dengue. The most frequent symptoms were fever, headache, vomiting, and muscle and joint pains. The tourniquet test was positive and thrombocytopenia was confirmed in 56% and 44% of the patients, respectively. Epistaxis (67%) was the most common hemorrhagic sign. Of the 356 serum samples received through the dengue surveillance systems in October 1994, IgM antibodies were detected in 43%. The virus was isolated from 5 of 24 samples tested (serotype 3 from 3 and serotype 1 from 2). The reintroduction of serotype 3 of dengue into the Region was demonstrated, along with its ability to produce epidemics of hemorrhagic dengue. The countries are warned that if they do not quickly take the measures described in the guidelines for the prevention and control of dengue and dengue hemorrhagic fever, new epidemics may occur in the Americas, given the large number of persons susceptible to this serotype and the high density of the mosquito vector in most of the countries of the Region.

Adolescent↗
PubMed1996

[Direct sequencing of an amplified product from a serum sample].

It is reported the nucleotide and amino acidic sequence of a great variability region in the dengue 2 virus genome, starting from the RNA of the original virus with no passage in the isolation systems. It is compared with the first strain of dengue 2 isolated during the 1981 epidemic with 4 passages in lactating mouse. Results show that the nucleotide sequence of serum and of strain A15 are the same.

Amino Acid Sequence↗
PubMed1996

[Genetic relatedness of the dengue 3 virus isolated in the outbreak of dengue hemorrhagic fever in Nicaragua, 1994].

It is reported the isolation of 2 dengue strains, 3 in samples from Nicaraguan patients suffering from dengue with hemorrhagic manifestations, which showed the reintroduction of this serotype in the region after being 17 years out of circulation. It is also reported the genetic characterization of the isolated strain, which, according to its classification, belongs to the group of dengue 2 strains isolated in Southeast Asi and which have been associated to hemorrhagic dengue. These results suggest the origin of this strain.

Amino Acid Sequence↗
PubMed1995

Expression of mdr-1 in refractory lymphoma: quantitation by polymerase chain reaction and validation of the assay.

Measurement of P-glycoprotein and the gene that encodes it, mdr-1, is an important tool for assessing the impact of multidrug resistance in clinical cancer. We evaluated mdr-1 expression by a quantitative polymerase chain reaction (PCR) assay in 78 biopsy samples from 48 patients with refractory lymphoma enrolled on a trial of infusional chemotherapy (EPOCH) in which R-verapamil was added as an antagonist of P-glycoprotein in a subset of patients whose tumors were unresponsive to treatment. Expression of mdr-1 was detectable in all biopsies at the time of enrollment on study, and a fourfold or greater increase in mdr-1 expression was noted in 42% of patients at the time of treatment failure. Expression of mdr-1 was also detectable in biopsies from patients at the time of diagnosis of lymphoma. An endogenous control gene, beta 2-microglobulin, was quantitated for normalization of the mdr-1 values. The use of beta 2-microglobulin expression for normalization was validated in a subset of samples by comparing Northern blots detecting beta 2-microglobulin, beta actin, and GAPDH gene expression. Immunoblot analysis suggested that no major discrepancy was present between mRNA expression and protein level. Immunophenotyping of lymphomatous lymph nodes showed that infiltration of tumor cells ranged from 8% to 95% and of normal T cells from 1% to 83%. Expression of mdr-1 in normal T cells and monocytes was also shown to be low. The mdr-1 levels in patient samples were independent of T-cell contamination, suggesting that the presence of normal cells has at best a small impact on mdr-1 measurements. Expression of mdr-1 in lymphoma can be quantitated by PCR, and wide variations in expression can be observed. Increased expression in patients with refractory disease supports an important role for Pgp in drug resistance in lymphoma. These studies will aid in the design and interpretation of clinical trials in lymphoma.

ATP Binding Cassette Transporter, Subfamily B, Mem↗