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Biomedical subjects

M Concha

Publications and source records attributed to M Concha.

At least 55 records · Page 3Linked to original sources
PubMed1994

Cerebrospinal fluid human immunodeficiency virus type 1 (HIV-1) p24 antigen levels in HIV-1-related dementia.

Human immunodeficiency virus type 1 (HIV-1) p24 antigen, a putative marker of virus load, was assayed in 79 blood and 83 cerebrospinal fluid (CSF) samples from 90 HIV-1-seropositive individuals with or without dementia. Twenty-eight subjects had no evidence of neuropsychological impairment, 17 had mild impairment without objective evidence of dementia, and 45 were demented. HIV-1 p24 antigen was detected more frequently in CSF samples from demented (19/40) than normal (1/26) or mildly impaired (1/17) subjects and in 67% of individuals with significant dementia (MSK stages 2-4). p24 Antigen was detected less frequently in CSF from demented subjects on antiretroviral drugs than untreated demented individuals. Overall, the sensitivity of the antigen capture assay in CSF among demented individuals was 47.5%; the specificity, 95.0%; positive predictive value, 90.4%; negative predictive value, 66.1%; and the efficiency, 72.2%. A direct relationship was also noted between the degree of cognitive impairment and blood p24 antigen detection frequency and antigen concentration. CD4+ blood lymphocyte counts were lower for demented individuals, and HIV-1 p24 antigen was detected more frequently and p24 antigen concentration was higher in blood and CSF from individuals with low CD4+ blood lymphocyte counts. beta 2-Microglobulin levels were higher in CSF from demented subjects and correlated directly with CSF p24 antigen concentration. However, in contrast to CD4+ blood lymphocyte counts and beta 2-microglobulin levels, only p24 antigen concentration correlated with dementia severity. Therefore, p24 antigen can be a useful marker for dementia related to HIV-1 infection.

AIDS Dementia Complex↗
PubMed1994

Production of extracellular xylanases by Penicillium janthinellum. Effect of selected growth conditions.

Xylanase production by Penicillium janthinellum using 10-100 mM of 2,2-dimethylsuccinate (DMS) buffer, in a range of pH 4.5-6.0 was studied. The enzyme activity was enhanced using oat xylan as the carbon source. Under these conditions a culture produced 1.14 mumol/min (11.4 U/mL or 84.4 U/mg) of beta-xylanase after 5 d of growth in a 10-mM buffer solution at pH 4.5. Protease was absent in the DMS buffer except when 100 mM phosphate buffer at pH 6.0 was used (4 U/mL). beta-Xylosidase was only found at a pH of 4.5 in all the buffer concentrations. At a 50 mM DMS buffer concentration at pH 4.5 beta-xylanases were induced by both oat and birch xylans, having a greater effect with oat spelt xylans. Electrophoretic analyses showed that the birchwood xylan induction exhibited different proteins profiles. No beta-xylosidase or beta-glucosidase was induced until d 5. The beta-xylanases were rapidly inactivated at 50 degrees C, however, birch xylanase appeared to be more stable than oat xylanase. Using oat xylan as an inductor, the beta-xylosidase and beta-glucosidase were 85 and 91 U/L, respectively, on d 7. The xylanase produced by induction from sugar cane bagasse hydrolyzate was used for pulp biobleaching. A 20% decrease on the Kappa value in Kraft pulp using the culture extract was obtained. These selective growth conditions led us to modulate the xylanase production for pulp delignification.

Avena↗
PubMed1994

Comparative evaluation of pentoxifylline, buflomedil, and nifedipine in the treatment of intermittent claudication of the lower limbs.

In the light of the current controversy surrounding the use of hemorheologic and vasodilator drugs in the treatment of peripheral arteriosclerosis, a comparative study was designed in order to evaluate the efficacy of pentoxifylline, buflomedil, and nifedipine in 45 patients with peripheral arterial disease (Fontaine stage II). The patients in this prospective randomized study were divided into three groups: 15 patients received pentoxifylline treatment (1,200 mg/day), 15 were treated with buflomedil (600 mg/day), and 15 with nifedipine (60 mg/day). Response to treatment was assessed at the start of the study and after forty-five and ninety days, by clinical examination, Doppler test, strain test, and digital occlusion plethysmography using a strain gauge ring. Pentoxifylline was significantly more effective (P < 0.05) than buflomedil and nifedipine at ninety days in improving walking performance, resting toe pressure, resting and postexercise ankle/brachial pressure ratio, and basal/postischemic toe-pulse ratio. Significant differences within groups were also noted for initial claudication, toe peak-flow time, pulse reappearance time (PRT/2), and maximum postischemic flow time, together with significant intergroup variables. In conclusion, pentoxifylline proved more effective than the other drugs tested in: 1. improving distal pressure and resting microcirculatory blood flow; 2. increasing postexercise distal flow, ratios, and pressures and enabling faster recuperation of basal pulse rates; 3. increasing initial claudication distance in the strain test within the test group and achieving a greater absolute subjective claudication distance than that obtained using the other treatments.

Adult↗
PubMed1994

[Postoperative analgesia for ambulatory surgery in children: a comparison of 2 techniques].

In 40 children scheduled for circumcision, we studied the quality and the adverse effects of postoperative analgesia induced by caudal block (group 1) or acetaminophen by rectal route (group 2). Study lasted the six first postoperative hours. In recovery room, analgesia was more effective in group 1. Need of analgesic drugs was also lesser in group 1. Incidence of adverse effects was the same in the two groups.

Acetaminophen↗
PubMed1994

[The echocardiographic findings in patients with brain death. The implications for their selection as heart transplant donors].

INTRODUCTION AND AIMS: Brain death causes myocardial impairment by some mechanisms not yet well understood. The aim of this work was to assess the echocardiographic features found in these patients and their implication in donor selection for heart transplantation. METHODS: With this aim, we have studied 38 consecutive patients with brain death assessed as possible donors for heart transplant in our hospital in the last 3 years. Age was 23 +/- 13 years; 77% were male. No history of cardiac disease was present in any patient. An adequate transthoracic echocardiogram was obtained in 74% of patients; transesophageal view was used in the remaining 26%. RESULTS: Echocardiogram was strictly normal in only 14 patients (37%). Mild valvular alterations were found in 5 patients (13%); a dilated aortic root in 1 (3%); moderate concentric left ventricular hypertrophy in 5 (14%); mild pericardial effusion in 1 (3%); mild septal hypokinesia with normal left ventricular ejection fraction in 4 (10%); abnormal left ventricular diastolic function in 7 (18%); and diffuse hypokinesia with ejection fraction less than 60% in 14 (37%). In 7 patients (18%) ejection fraction was lower than 40% (one of them was cocaine-addict). Mean ejection fraction was 59 +/- 15% (23 to 83%). Only 2 of the 19 (10%) donor hearts implanted in our hospital showed early dysfunction after transplant, but no relation to pretransplant ejection fraction was found. Ejection fraction increased from 62% pretransplant to 73% at one week after transplant in the other 17 cases. CONCLUSIONS: Brain death commonly causes alterations of left ventricular function, and this impairment is severe in almost 20% of cases. These echocardiographic features must be known when selection of donors for heart transplantation is concerned.

Adolescent↗
PubMed1994

[The incidence, mechanisms and clinical factors predictive of sudden death in patients with severe heart failure evaluated in anticipation of heart transplantation].

INTRODUCTION AND OBJECTIVES: Sudden death is not uncommon in patients with severe congestive heart failure. The aim of our study was to assess the incidence, mechanisms and clinical predictors of sudden death in a large series of patients with severe congestive heart failure evaluated for heart transplantation. METHODS: With this aim we have reviewed our experience on 240 consecutive patients with severe heart failure studied in our hospital from May 1986 to June 1992. Heart failure was due to ischemic heart disease in 35% of patients and idiopathic dilated cardiomyopathy in 65%. Age was 47 +/- 12 years, left ventricular ejection fraction was 20 +/- 6%, and symptom class was IV in 88% of patients and III in 12%. RESULTS: Sixty-eight of the 240 patients (28%) died without transplantation. Death was sudden in 21 patients (31% of deaths, and 9% of all patients), due to heart failure in 41 (68%), and due to malignancy (ampuloma) in 1 (1%). Mechanism of sudden death could be identified in 12 cases: ventricular tachycardia/fibrillation in 8 and bradycardia/electromechanical dissociation in 4. On multivariate analysis (stepwise logistic regression), a lower tolerated captopril dosage (p = 0.004), a lower systolic blood pressure (p = 0.079) and a history of a ventricular tachycardia/fibrillation (p = 0.073) were independent predictors of sudden death. CONCLUSIONS: It seems possible to identify, between patients with severe heart failure, a subgroup of patients at higher risk for sudden death by means of such simple clinical parameters.

Acute Disease↗
PubMed1994

Operative management of a persistent sciatic artery aneurysm.

A 60-year-old man with a painful pulsatile mass approximately 8 cm in diameter in the right buttock was diagnosed using angiography as having a complete unilateral persistent sciatic artery aneurysm. The lesion was obliterated by proximal and distal ligation of the sciatic artery at the pelvis and the adductor magnus canal. A femoropopliteal bypass was performed with inverted autologous saphenous vein. The residual mass was subsequently drained because of persistent symptoms. Postoperative recovery was good.

Aneurysm↗
PubMed1994

[Short- and long-term course of heart transplantation recipients with severe dysfunction of the graft associated with acute rejection].

INTRODUCTION AND OBJECTIVES: Acute rejection is still a common cause of death after heart transplantation, in spite of cyclosporine. The aim of our study was to assess the incidence of severe graft dysfunction associated with acute rejection and the short and long-term outcome of these patients. METHODS: Ten of our 100 first heart transplant patients have developed rejection-induced severe cardiac dysfunction (left ventricular ejection fraction determined by echocardiography < 35% associated with 3A, 3B or 4 acute rejection). Clinical outcome, complications and evolution of left ventricular function were studied. RESULTS: Five patients were given intravenous methylprednisolone 500 to 1000 mg/day for 3 days. The other 5 patients had severe heart failure and received antilymphocyte antibodies. Three patients treated with methylprednisolone alone and one patient treated with antilymphocyte antibodies died within the first week after therapy. Left ventricular ejection fraction increased from 26 +/- 4% to 51 +/- 6% at 1 month after therapy in the 6 survivor patients. Four of the 6 survivor patients also died before 1 year after rejection (3 due to infection). Thus, long-term, overall mortality was 80%. CONCLUSIONS: Although favorable short-term results can be achieved in patients with rejection-induced severe cardiac dysfunction with immunosuppressive therapy (mainly antilymphocyte antibodies), long-term prognosis seems poor, due to the increased rate of life-threatening infections.

Acute Disease↗
PubMed1993

Clinical and hemodynamic predictors of survival in patients aged < 65 years with severe congestive heart failure secondary to ischemic or nonischemic dilated cardiomyopathy.

To identify which clinical or hemodynamic parameters predict survival in patients with end-stage heart failure due to dilated cardiomyopathy, 130 consecutive patients aged < 65 years (mean 46 +/- 13) assessed for heart transplantation from May 1986 to April 1991 were studied. Mean follow-up was 15 +/- 11 months. Left ventricular ejection fraction was 22 +/- 7%. Left ventricular end-diastolic pressure was 27 +/- 9 mm Hg, and cardiac index was 2.2 +/- 0.6 liter/min/m2. Symptom class was IV in 91% of patients and III in 9%. Etiology was ischemic in 40% of patients and idiopathic in 60%. After intensive medical therapy, heart transplantation was considered indicated in 53% of patients, contraindicated in 20% and not indicated in 27%. Transplantation was performed in 36% of patients during follow-up, and 35% died and 29% were alive without transplantation. A comparison, excluding patients with transplantation, was performed between those who were alive and had survived > or = 6 months after assessment, and those who died. On multivariate analysis, the following 3 parameters were independent predictors of prognosis: intravenous inotropic requirement (p < 0.001), maximal, tolerated captopril dose (p = 0.013) and systolic blood pressure (p = 0.003). When patients with transplantation were considered as deaths, stabilization on medical therapy also reached statistical significance (p = 0.009). Classic prognostic markers including ventricular arrhythmias, left ventricular end-diastolic pressure, cardiac index, amiodarone therapy and etiology were not associated with prognosis in this homogeneous population of severely ill patients.

Adolescent↗
PubMed1993

Physical interaction between Langerhans cells and T-lymphocytes during antigen presentation in vitro.

Physical interaction between Langerhans cells and T cells is an essential requirement for antigen presentation. In this study we report the ultrastructural characteristics of the antigen-specific physical interactions that occur in vitro between murine Langerhans cells and T cells. Epidermal Langerhans cells enriched to 78% purity by a panning method were pulsed with 2,4-dinitrophenyl-Limulus polyphemus hemocyanin and co-incubated with syngeneic T lymphocytes primed in vivo with the same antigen. A substantial number of conjugates constituted by Langerhans cells surrounded by three or more lymphocytes were obtained after 60 min of incubation at 4 degrees C. Electron microscopy of the conjugates revealed that Langerhans cells and T lymphocytes interacted by two type of contacts. Type I was characterized by glycocalyx-glycocalyx interaction that occurred in relation to protrusions or microvilli of both cells. Type II was characterized by wide and tight areas of close apposition between Langerhans cells and T-lymphocyte plasma membranes. In these areas there were zones with intercellular bridges and small septilaminar junctions highly suggestive of gap junctions. An electron-immunogold procedure demonstrated the presence of DNP-LPH antigen on the type I contact. Our findings suggest that type I contact may represent the locus for antigen presentation whereas the type II contact may be involved in keeping adhesiveness between Langerhans cells and lymphocytes during antigen presentation.

Animals↗
PubMed1993

Early open mitral commissurotomy: long-term results.

It has frequently been suggested that early mitral commissurotomy could improve long-term results in patients with severe mitral stenosis. However, the real advantages of this procedure have yet to be demonstrated. To evaluate this hypothesis, we retrospectively studied 397 patients who underwent operation for mitral stenosis in our unit between 1978 and 1988. Forty of these patients (group I) fulfilled the criteria for early mitral commissurotomy: being young (average age 33 years), being asymptomatic or showing few symptoms, and being in sinus rhythm. The remaining 357 patients who underwent operation during the same period of time served as control (group II). Mitral valve replacement (p < 0.05) and associated tricuspid annuloplasty (p < 0.05) occurred less frequently in patients from group I than it did in patients from group II. Survival after 11 years for patients with early mitral commissurotomy was 100%, 90% of whom were in functional class I, were in sinus rhythm, and were receiving no medication whatsoever. Ninety-six percent of these patients were free of complications after 11 years, compared with 73% of patients in group II (p < 0.05). In our opinion, these results support the use of early mitral commissurotomy for young patients in sinus rhythm, who are symptom free, who are and who have a mitral valve area is 1.3 cm2 or less.

Adolescent↗
PubMed1993

[Orthotopic heart transplant. Study of early morbimortality (< or = 30 days). Experience at the Reina Sofía Hospital (Córdoba)].

From may 1986 to december 1991, we have performed 90 heart transplantation in the Hospital "Reina Sofía" from Córdoba. In the present study we analyze the early morbidity and mortality in a retrospective study on complications and factors determining its incidence. Seventy patients were male (86%) and 13 female (14%). Age ranged from 12 and 65 years. The 31% of patients needed in pharmacological support before transplantation, 15 of them were operated in a emergency situation because of cardiogenic shock. The pulmonary resistances oscillated between 0.5 and 8.7 units/m2 (Wood) (mean 2.5 +/- 1.4 units/m2). The mean time of ischaemia was 136 +/- 38 minutes (range 5-255 min). Hospital mortality (< or = 30 days) was 8.8% (8/90). No predictive factors from donor and recipient were found. Three main influences on complications were analyzed: a) influence of myocardial temperature, b) role of hematic cardioplegia, and c) usefulness of Aprotinin. Eighteen patients (20%) developed severe bradyarrhythmia needing a pacemaker in the post-operative period. We found a significant relationship with myocardial temperature (4.3 +/- 2.1 vs 6.2 +/- 2.6; p < 0.05) and transport solution temperature (5.8 +/- 2.3 vs 7.3 +/- 1.9; p < 0.05). No significant influence was found on the time of ischaemia, previous heart disease, previous treatment with Amiodarona, clinical condition, etc.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗
PubMed1992

Effect of chronic substance abuse on the neuropsychological performance of intravenous drug users with a high prevalence of HIV-1 seropositivity.

Limited data are available on cognitive performance in populations of intravenous drug users during the early, asymptomatic stages of human immunodeficiency virus type 1 (HIV-1) infection. Between 1988 and 1990, 151 participants from the AIDS Link to Intravenous Experience (ALIVE) Study in Baltimore, Maryland, were evaluated neuropsychologically on a semiannual basis. This analysis focused on whether history of substance abuse influenced neuropsychological test performance. At baseline, 102 participants were HIV-1-seropositives who were free of acquired immunodeficiency syndrome and 49 participants were seronegative. Multivariate analyses, adjusting for correlation of repeated outcome measures, were conducted to determine predictors of neuropsychological functioning. Effects of the frequency of reported past use of marijuana, heroin, cocaine, barbiturates, and alcohol were not statistically associated with performance on the tests. Age and education were the most important predictors of test performance, and a significant practice effect was observed for most measures. After adjustment for age, education, the practice effect, and frequency of drug use, neuropsychological performance over time did not vary by HIV-1 serostatus. Overall, after acutely intoxicated individuals were excluded, neither frequency of drug and alcohol use nor HIV-1 seropositivity significantly influenced neuropsychological test performance over a 1-year period.

Adult↗
PubMed1992

The activation antigen CD69 is selectively expressed on CD8+ endomyocardium infiltrating T lymphocytes in human rejecting heart allografts.

We analyzed the presence of T-cell subsets (CD4/CD8) and the activation markers CD25 and CD69 in the cellular infiltrates of endomyocardium biopsies taken from transplanted human hearts. The results indicate that CD25 was present within specimens mainly infiltrated by CD4+ cells. In contrast, CD69 was found in infiltrated biopsies by CD8+ cells, as determined by single immunofluorescence. Double immunoenzymatic staining was used to investigate the cellular distribution of the activation markers studied in some representative cases. Thus, CD25 was found on both CD4+ and CD8+ cells while CD69 molecule was selectively expressed on CD8+ T-cell subset. These results suggest that CD69 is a surface molecule relevant to the CD8+ cell-mediated graft rejection events of allografted human hearts.

Antigens, CD↗
PubMed1992

Seroprevalence and cofactors of HTLV-I infection in Tumaco, Colombia.

This study presents an analysis of the factors associated with HTLV-I seroprevalence in the endemic area of Tumaco, Colombia. During June to August 1988, 1,077 individuals were selected at random from a population of 45,594. The overall prevalence rate of HTLV-I antibodies was 2.8%. Among females prevalence was significantly higher (p less than 0.02) than among males. Rates increased substantially with age. HTLV-I prevalence among individuals with history of use of intravenous medications was significantly higher (p less than 0.001) than in those without such history. Logistic regression analysis included age in years, indicators for male gender, and for i.v. injections, and their interactions. Age was very strongly associated to HTLV-I infection among females. At early ages prevalence was not different between sexes, but females presented a significantly higher rate than males after age 42. History of i.v. administered medications was very strongly associated in the univariate analysis and, although significance was borderline in the multivariate analysis, it had the effect of doubling the odds of HTLV-I infection.

Adolescent↗
PubMed1992

Glomerular localization of platelet factor 4 in streptococcal nephritis.

Since platelet factor 4 (PF4), a cationic (pI 7.6) platelet secretory protein, binds avidly to glomerular polyanions both in vitro and in vivo, and is implicated in neutrophil chemotaxis, we studied by indirect immunofluorescence microscopy the presence of PF4 deposits in glomeruli of patients with poststreptococcal nephritis (APSGN). Goat antihuman PF4 serum was used as primary antibody and fluorescein-conjugated IgG fraction of rabbit antigoat IgG as second antibody. Controls consisted of nonimmune goat serum or anti-PF4 serum preabsorbed with human PF4, as primary antibodies. Glomerular deposits of PF4 were demonstrated in renal tissues obtained by biopsy in 14 of 20 patients studied; the deposits were particularly intense in 9 patients. PF4 was bound to the mesangium and to the capillary walls. There was a significant positive correlation between intraglomerular deposits of PF4 and the levels of proteinuria (p = 0.024). These findings provide further evidence for a role of platelets in the pathogenesis of APSGN and suggest that PF4 may contribute to alter the glomerular permeability in this disease.

Adult↗
PubMed1992

HIV-1 infection and intravenous drug use: longitudinal neuropsychological evaluation of asymptomatic subjects.

A previous baseline cross-sectional comparison of cognitive performance of a group of AIDS-free, HIV-seropositive intravenous drug users with seronegative control intravenous drug users revealed no significant differences attributable to HIV. We now present longitudinal follow-up results from the same cohort of 160 intravenous drug users. There were no differences in performance by serostatus group at either 6- or 12-month follow-up visits, although differences by age and education were observed. Improvement in performance secondary to practice effects was comparable in both serostatus groups. These findings confirm that chronic intravenous drug use may be associated with a wide range of neuropsychological deficits, but there is no evidence that such preexisting deficits interact with HIV infection to produce additional cognitive impairment in otherwise asymptomatic intravenous drug users. Together with results from other high-risk groups such as homosexual/bisexual men and hemophiliacs, these results confirm that neurocognitive abnormalities during the presymptomatic stages of HIV infection are rare, regardless of the route of acquisition of the virus.

Adult↗