Search PubMed⌕ Search

Biomedical subjects

J M Alvarez

Publications and source records attributed to J M Alvarez.

At least 55 records · Page 3Linked to original sources
PubMed1997

[The clinical characteristics of pulmonary tuberculosis in the elderly].

Pulmonary tuberculosis remains as a significant clinical problem in the elderly. To describe age-related differences in disease manifestations, a comparison was made taking in consideration predisposing factors, clinical features, radiographic findings and diagnostic approaches in cases of pulmonary tuberculosis between two groups: equal o higher of 60 years and lower of 60 years. Elderly patients had a higher number of antecedents of previous tuberculosis and underlying diseases than younger patients. At admission, symptoms like fever and hemoptysis were more frequent in the younger group. Radiographic findings revealed that upper lung infiltrates were still common in both groups, and that elderly patients presented less pleural effusions and cavitary lesions than younger patients. Since there were differences in the clinical presentations of pulmonary tuberculosis in the elderly group, a high index of suspicion for the disease should be maintained.

Adult↗
PubMed1996

Pyrene-labeled DNA probes for homogeneous detection of complementary DNA sequences: poly(C) model system.

DNA and RNA probes are important analytical reagents in molecular biology and in the detection of infectious and genetic diseases. However, the present polynucleotide probe technology is complex and labor-intensive. We have been investigating the possibility of using fluorescent-labeled DNA probes to develop assays which do not require the separation of free from hybridized probe (homogeneous assays). Such assays are possible if the fluorescence efficiency or fluorescence anisotropy of the fluorescent label changes upon hybridization of probe with target DNA. In this article we examine pyrene as a fluorescent label for DNA or RNA probes. Experiments were performed using a model system in which poly(C) and poly(I) are respectively the probe and target sequences. A small fraction of the nucleotide bases of poly(C) was randomly labeled with pyrene using the bisulfite-catalyzed diamine reaction. The results show that the uncorrected emission spectrum of pyrene-poly(C) decreases by a factor of 4 and shifts toward longer wavelengths upon hybridization with poly(I) at saturating concentrations. The average lifetime changes from 10.78 to 4 ns. These fluorescence changes occur in a wide range of chemical environments, including the high salt concentrations normally used to increase the velocity of the hybridization reaction in clinical assays. The pyrene label can thus be used to readily detect the amount of poly(I) in an unknown sample without having to separate free and bound labeled probe. To unravel the mechanism responsible for the observed changes in fluorescence intensity upon hybridization, we have performed polarized fluorescence intensity measurements and analyzed the results by approximate steady-state expressions that allow evaluation of the relative contributions of changes in lifetimes (fluorescence efficiency) and rotational motions to the changes in fluorescence intensity. The results indicate that the latter changes are due chiefly to changes in lifetime or fluorescence efficiency and that these changes seem to be due to the movement of the pyrene label to a more hydrophilic environment upon hybridization.

DNA Probes↗
PubMed1996

Repairing the degenerative mitral valve: ten- to fifteen-year follow-up.

From January 1969 to December 1992, mitral valve reconstructive operations were performed on 155 patients with degenerative mitral valve disease. There were 102 male and 53 female patients, with a mean age of 60.5 +/- 9.2 years, a mean duration of symptoms of 3.8 +/- 2.7 years, and 34% were in atrial fibrillation. All patients were in New York Heart Association functional classes III and IV before operation. The degree of mitral regurgitation was severe in 94% and moderate in 6%, and 50.9% of patients had moderate to severe impairment of left ventricular function. Emergency operation was undertaken in 7.1% of cases; 19% of patients underwent additional procedures. All patients had posterior mitral leaflet pathology and 19 patients had anterior mitral leaflet pathology. Ring annuloplasty was used in only 3% of cases. The operative mortality rate was 3.9%, 9% of patients had morbid events, and 4.5% of patients had repair failure within 6 months. All patients have been followed up with serial echocardiography for a mean time of 5.2 +/- 0.3 years (range 0.5 to 24 years). Immediately after operation, 92.9% had no mitral regurgitation to mild mitral regurgitation. At last follow-up, 96.9% had no mitral regurgitation to mild mitral regurgitation by echocardiography and 98% of patients were in New York Heart Association functional classes I and II. The actuarial survival at 15 years was 46% +/- 11%, freedom from reoperation was 84.9% +/- 11%, freedom from infective endocarditis was 96.0% +/- 11%, freedom from thromboembolism was 90.4% +/- 11%, and freedom from all valve-related events was 36.7% +/- 11%. It is well documented that repair of degenerative mitral valves offers excellent short-term and medium long-term benefits. This series represents the longest follow-up reported outside Europe. Our results beyond 10 years support our conclusion that an annuloplasty ring is not an absolute prerequisite for achieving successful repair of proven durability in most patients with degenerative mitral valve disease.

Actuarial Analysis↗
PubMed1996

Ig-isotype patterns of primary and secondary B cell responses to Plasmodium chabaudi chabaudi correlate with IFN-gamma and IL-4 cytokine production with CD45RB expression by CD4+ spleen cells.

In this work, the authors analysed T and B lymphocyte subsets and cytokine production in the spleen of BALB/c mice during polyclonal lymphocyte activation (primary infection) and parasite-specific response to Plasmodium chabaudi chabaudi (secondary infection). The secondary response was evaluated in fully immunoprotected animals, 60 days after a chloroquine-cured infection. The authors observed that in polyclonal lymphocyte activation antibody-secreting cells of all isotypes increased, with predominance of IgG2a and IgG3 classes. At that time, IFN-gamma was largely produced, but IL-4/IL-5 were just slightly enhanced. In mice re-infected after 60 days, the Ig-isotype pattern was restricted to IgG1 and only IL-4/IL-5 were produced. In both responses, however, the levels of IL-2 were greatly reduced, while those of IL-10 were enhanced to similar levels. The different involvement of Th1 and Th2 cells in both responses was confirmed through analysis of CD45RB expression by CD4+ cells. The authors observed that CD45RBhigh cells were the major CD4+ subpopulation in primary infected mice, while CD45RBlow cells predominated in 60 days re-infected animals. Moreover, the great majority of activated (large) CD4+ cells in the primary infection belonged to the CD45RBhigh subset, while after reinfection most of the CD4+ large had a CD45RBlow phenotype.

Animals↗
PubMed1995

Effect of pH on injection phlebitis.

Formulation pH has been reported to be responsible for the incidence of phlebitis. In this study, the effect of pH on injection phlebitis is investigated. Buffers of varying pHs were examined for their ability to produce phlebitis in rabbits. Thermal measurements as well as visual evaluations were used for phlebitis quantitation. The results show that formulation pH between 3.0 and 11.0 does not contribute to the incidence of phlebitis when administered as an iv bolus injection.

Animals↗
PubMed1995

The use of ultra-low-dose aprotinin to reduce blood loss in cardiac surgery.

One hundred patients due to undergo primary cardiac surgery were prospectively randomized to receive aprotinin or placebo. In the aprotinin group, 250,000 kallikrein inhibitory units (KIU) of aprotinin were added to the cardiopulmonary bypass prime solution. A further 250,000 KIU of aprotinin were infused intravenously over 30 minutes immediately before the start of cardiopulmonary bypass. The control group received 0.9% saline in equal volumes at identical times. The study was designed to have a 90% chance of demonstrating a 30% reduction in blood loss. No significant differences were found between the two groups. The median blood loss in the aprotinin group was 750 mL (interquartile range 556 to 1025 mL, 95% confidence interval 600 to 800 mL). In the control group, the median blood loss was also 750 mL (interquartile range 500 to 988 mL, 95% confidence interval 625 to 925 mL). In the aprotinin group, 12 patients received postoperative autotransfusion of shed mediastinal blood of median volume of 665 mL (interquartile range 500 to 925 mL, 95% confidence interval 450 to 1000 mL). In the control group, 14 patients received postoperative autotransfusion of mediastinal blood of median volume of 663 mL (interquartile range 600 to 800 mL, 95% confidence interval 600 to 700 mL). Five patients in the aprotinin group and seven patients in the control group required postoperative homologous blood transfusion. Reassessment of inclusion criteria showed a 19% reduction in blood loss in patients undergoing only aortocoronary bypass receiving aprotinin compared with controls.(ABSTRACT TRUNCATED AT 250 WORDS)

Aprotinin↗
PubMed1994

A new mutant hairless mouse with lymph node hyperplasia and late onset of autoimmune pathology.

Adult BALB/c male mice were injected with a single dose of ethyl nitroso urea (ENU; 250 mg/kg, i.p.) and mated to C57BL/6, DBA/2 and A/J adult females 13 weeks later. F1 males were mated with BALB/c females and F2 females were than backcrossed to the F1 parents. One BALB/c male mouse thus treated gave origin to a mutant presenting hair and skin alterations similar to those of natural hairless mutants. The new mutation is located on chromosome 14 near the Es10 locus, and probably at the same locus for the hairless mutation. Similar to the hairless mouse, this new mutant has a normal phenotype at birth and after three weeks starts to loose hair which is never replaced. Additionally, the skin becomes thickened and wrinkled. One feature that distinguishes this mutant from other hairless mice is the peculiar enlargement of its axillary and cervical lymph nodes. The new mutant develops membranoproliferative glomerulonephritis similar to the rhino mouse, one of the hairless allele mutants already described in the literature, but with a much later onset.

Animals↗
PubMed1993

Intra-aortic balloon rupture causing femoral entrapment.

Rupture of an intra-aortic balloon counterpulsator (IABCP) demands immediate removal. We report a case of thrombus formation within a Datascope IABCP secondary to IABCP rupture, necessitating surgical exploration for removal. There is a disturbing pattern of balloon ruptures with this type of IABCP.

Aged↗
PubMed1993

Repair of the anterior mitral leaflet.

BACKGROUND: Repair rather than replacement of the diseased mitral valve has been the goal of the cardiac surgeon. Although well accepted for posterior leaflet pathology, a diseased anterior leaflet was believed by some to be irreparable. AIMS: To assess the result of reconstructive mitral valve surgery involving the anterior mitral leaflet in a selected group of patients. METHODS: Twenty consecutive patients with degenerative (19), ischaemic (one) and congenital/calcific mitral regurgitation were evaluated. There were five females and 15 males with a mean age of 62 +/- 12 years (41-75 years). The technique used to repair these valves included chordal transposition, leaflet plication commissuroplasty and a new technique we call leaflet repositioning. RESULT: There were no deaths, follow-up is complete with mean follow-up of 31 +/- five months (two-102) months. All patients have had 2DE and 13 TOE as well. There have been no reoperations due to failure of the repair, 95% of patients are in NYHA Class I-II post operative, while 15% have significant residual regurgitation.

Chordae Tendineae↗
PubMed1993

[The female sex and mortality after acute myocardial infarct].

INTRODUCTION: To study the possible influence of gender on in-hospital mortality in patients suffering acute myocardial infarction. PATIENTS AND METHODS: We analyzed 1,951 consecutive patients admitted to our Coronary Unit between January 1986 and December 1991 with this diagnosis and with a delay of no more than 24 hours prior to admission. RESULTS: In-hospital mortality was 12.8% in the 1,603 males and 25.6% in the 348 females (p < 0.001). Age, previous history of: not smoking, diabetes, heart failure, stable angina, myocardial infarction, stroke, right branch block, atrial fibrillation, and treatment with digoxin were variables significantly associated with greater mortality (p < 0.05) as well as the localization of the infarction, the Forrester grade and/or presence of atrioventricular block on admission and not treatment with intravenous fibrinolytics and beta-blockers. Multivariate analysis of variables associated with mortality (selection criterion for variable entry p < 0.20) shows that age, gender, previous angina, situation and extension of the infarction determined by ECG and Forrester on admission are independent predictors of in-hospital mortality. CONCLUSIONS: Gender is an independent predictor of in-hospital mortality in acute myocardial infarction (female/male odds ratio = 1.63).

Aged↗
PubMed1992

Repairing the degenerative anterior mitral leaflet.

This is a consecutive, nonselected series of 18 patients with degenerative mitral regurgitation requiring a reparative operation on the anterior mitral leaflet. A new technique of double-breasting the two leaflets when flail septal segments are encountered is introduced.

Adult↗
PubMed1992

Complications from intra-aortic balloon counterpulsation: a review of 303 cardiac surgical patients.

From January 1980 to January 1990 all patients undergoing cardiac surgery at the Royal North Shore Hospital, Sydney, and requiring intra-aortic balloon counterpulsation (IABCP) were retrospectively reviewed. A total of 99 patients (32.6%) developed complications. Vascular/haemorrhagic complications occurred in 46 patients (15.2%); 79 patients (26%) required platelet transfusions. We have found that only a history of hypertension was predictive of an increased incidence of developing vascular complications. Surgical intervention was required in 17 patients (5.6%), or 47% of the patients who developed a vascular complication. The mortality among patients requiring IABCP was 36.6%. Intra-aortic balloon pump-related deaths occurred in 6 patients (2%). Use of the intra-aortic balloon pump can be a life-saving procedure, but it carries a significant morbidity and mortality rate. This makes it imperative to temper our indications to those patients who demonstrate a need for it.

Adult↗