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Biomedical subjects

M Rodríguez

Publications and source records attributed to M Rodríguez.

At least 253 records · Page 14Linked to original sources
PubMed1995

Frequency source analysis in patients with brain lesions.

In a previous study (Harmony et al. 1993) we observed that the volume of lesions was correlated only with delta power, while the volume and density of edema showed a significant correlation with theta and alpha power, suggesting two independent origins of activity in the delta and theta bands in patients with space-occupying lesions. Our goal in this paper is to show, through a different technique, in a narrow band spectral analysis, that brain lesions are characterized by activity in the delta domain and that edema is better correlated with activity within the theta range. Frequency source analysis based on the Maximum Likelihood (ML) test for rejection of isotropicity was applied to the EEG at rest of 36 patients with space-occupying intracranial lesions. The ML test was rejected at frequencies below 1 Hz and in the low range of the delta rhythm in 31 patients. The origin of the equivalent dipoles at these frequencies was within the volume of the lesion in 27 patients. In 15 patients out of 19 with vasogenic edema the ML test was rejected at frequencies in the theta range. The equivalent dipoles at these frequencies were all within the volume of the edema.

Astrocytoma↗
PubMed1995

EEG activation patterns during the performance of tasks involving different components of mental calculation.

In this study we demonstrate the existence of different patterns of EEG activation during the performance of 4 different tasks involving different components of mental calculation in normal subjects. The EEG was recorded in all monopolar leads of the 10/20 system using linked ear lobes as reference. Absolute and relative power were calculated in the delta (1.5-3.5 Hz), theta (3.5-7.5 Hz), alpha (7.5-12.5 Hz) and beta (12.5-19 Hz) bands. The tasks were presented randomly and the EEG segments preceding presentation of the stimulus were considered as the rest corresponding to the task requested by the stimulus. Tasks were of 4 different types, involving number comprehension, recognition of mathematical symbols, the calculation process and the spatial component. ANOVAs between the rest periods showed no differences in any band. Neither did ANOVAs between tasks. However, other variables (task minus rest), which were calculated as the differences in power between task and rest respectively, showed significant differences between tasks in the delta and beta bands in the frontal lobes. In addition, new variables were calculated as the difference between tasks, since many factors were common across several tasks. These variables correspond to the EEG change due to a specific component of mental calculation. Significant differences were obtained in delta and theta bands in right posterior areas and in the beta band in frontal areas. We concluded that the EEG differences observed during different components of mental calculation suggest the participation of different networks.

Adult↗
PubMed1995

Comparison of Z and multivariate statistical brain electromagnetic maps for the localization of brain lesions.

Conventional Z maps provide probability statements about the deviation of observed values from the norm. Galán et al. (1994) introduced Simultaneous Significance Probability Scales to detect abnormalities over the whole map, making use of the information provided by the topographic structure of dependencies. They also described multivariate brain electromagnetic (MBE) maps for compact presentation of complex spatio-temporal information. In this paper, using the distance-based localization receiver operating characteristic curves (DL-ROC curves), we compare the localization provided by computed tomography with that provided by Z and MBE maps in 61 patients with brain lesions. Maps were calculated for absolute power and relative power in delta, theta, alpha and beta bands for voltage and current source densities (CSD). In each patient, all maps were compared and the map with the highest value of the area of the DL-ROC curve was considered to be the "best map." Z maps of CSD were the "best maps" in 24 patients. In the voltage montage, we observed that multivariate maps add some information not contained in the Z maps. However, for CSD, Z maps were more accurate than multivariate maps. A very consistent finding was the observation that lesions were better detected by maps analyzing the delta band, while edema was better represented by maps in the theta range.

Brain Damage, Chronic↗
PubMed1995

Longitudinal quantitative EEG study of children with different performances on a reading-writing test.

In a previous paper, using the same test for the evaluation of reading-writing abilities, Harmony et al. (1990b) reported that children with severe difficulties had more delta in fronto-temporal regions, and this was interpreted as a sign of underlying cerebral dysfunction. Children with severe and minor difficulties in the test had more diffuse theta absolute and relative powers and less alpha relative power. As theta decreases with age, while alpha increases, these results suggested that children with minor and severe difficulties in reading had a maturational lag with respect to those with normal performance. We conducted this study in order to test this hypothesis. Two different EEG records were obtained with an interval of 2.58-3.15 years in 49 children classified in 3 groups according to their performance in a reading-writing test. Group 1: adequate performance for age and degree (control group); group 2: below level performance with minor difficulties; and group 3: below level performance, with severe difficulties. The mean age of the groups in the first study was 9 years. Absolute (AP) and relative powers (RP) in the delta, theta, alpha and beta bands were computed for each session. In general, groups 3 and 2 showed greater changes than group 1 from session to session. ANOVAs performed by session clearly demonstrate many significant differences between groups in the first study, while few significant differences in parieto-occipital regions in theta RP were observed in the second session. These results point toward a maturational spurt of children from groups 2 and 3.

Brain↗
PubMed1995

Electroencephalographic coherences discriminate between children with different pedagogical evaluation.

The relationship of reading-writing ability and EEG coherences was studied in 84 subjects from two age groups 7.0-8.9 and 9-11.2 years old. All children were divided into three groups according to their performance on a pedagogical test: ped1, normal children; ped2, children with mild problems; ped3, children with reading-writing disability. The following results were obtained: in general, children showed higher coherences in groups with poor performance in the delta, theta and beta bands. In the alpha band, higher coherence values were related to better performance. The exceptions to this general pattern were rare. Group ped2 had higher coherences in delta, theta and alpha bands than ped1 and ped3, in left temporal leads. In older children the same tendency was observed, but group differences in the theta, alpha and beta bands were few. In this age range, the significant group differences were almost all interhemispheric coherences. The discriminant analysis that classified subjects by their coherence values gave very good results, fact that demonstrates, that EEG coherence is a highly sensitive measurement indicating not only the existence of a reading-writing problem, but also the degree of its severity.

Age Factors↗
PubMed1995

Effect of vaccination with a recombinant Bm86 antigen preparation on natural infestations of Boophilus microplus in grazing dairy and beef pure and cross-bred cattle in Brazil.

Current methods for the control of the cattle tick Boophilus microplus infestations are not effective and the parasite remains a serious problem for the cattle industry in tropical and sub-tropical areas. Recent advances have introduced the possibility for the immunological control of the parasite through the use of recombinant vaccines. Recently, it was shown that the recombinant vaccine Gavac (Heber Biotec S.A.) is able to control B. microplus populations in artificially infected grazing dairy cattle in Cuba. To assay the effect of the vaccine on a different B. microplus strain and under different ecological conditions, we conducted a trial in Brazil on grazing dairy and beef pure and cross-bred cattle under natural infestation conditions. A farm in the northeast of the state of Sao Paulo was selected and two groups of animals per breed were included in the experiment and were maintained grazing on separate but similar pastures. For each breed, one group was vaccinated with the vaccine Gavac and the second group was not vaccinated and was employed as a control. In vaccinated cattle, during 36 weeks of experiment, the average infestation rate was maintained below 78 ticks per animal while average infestation peaks (mean +/- S.E.) of 144 +/- 44 ticks per animal (for dairy cross-bred cattle) and 195 +/- 42 ticks per animal (for beef cross-bred cattle) were recorded in the control groups. Tick infestation rates showed statistical significant differences (p = 0.04) between both experimental groups throughout the experiment. These results clearly showed, as in the Cuban study, that the vaccine controlled tick numbers in successive generations in the field.

Analysis of Variance↗
PubMed1995

Control of Boophilus microplus populations in grazing cattle vaccinated with a recombinant Bm86 antigen preparation.

Current methods for the control of cattle tick Boophilus microplus infestations are not effective and the parasite remains a serious problem for the cattle industry in tropical and subtropical areas. Recently, we developed a vaccine against B. microplus employing a recombinant Bm86 (rBm86) antigen preparation (Gavac, Heber Biotec) and it was shown to induce a protective response in vaccinated animals under controlled conditions. Here we show that, under field conditions in grazing cattle, the vaccine is able to control B. microplus populations. Two parasite-free farms were employed for the study. In the first farm, animals were vaccinated with the recombinant vaccine, while, in the second, animals received a saline injection in adjuvant. After immunization, animals were artificially infected and the infestation rate was recorded. Over the 33 weeks of the experiment, the infestation rate was lower in the vaccinated group compared with the control group. At the end of the experiment it was necessary to use chemicals in the control farm after serious losses in production and animals.

Animals↗
PubMed1995

Sinus histiocytosis confined to the skin. Case report and review of the literature.

Sinus histiocytosis with massive lymphadenopathy is an uncommon disease affecting individuals of either sex and of all ages and ethnic backgrounds. We present a case of sinus histiocytosis confined to the skin in a 65-year-old woman whose diagnosis was coincident with herpes simplex virus infection and polybacterial urinary infection, both asymptomatic. The polymerase chain reaction for herpes simplex virus and human herpesvirus-6 from involved skin was negative. We review previously published cases of sinus histiocytosis limited to the skin.

Aged↗
PubMed1995

Caffeine test assessment for measuring liver function in critically ill patients.

Caffeine elimination was studied in 73 patients admitted to an intensive care unit, 33 of whom had liver disease. Mean plasma clearance of caffeine in patients with no liver disease (1.30 +/- 0.79 ml/kg/min) was significantly higher than in patients with liver disease (0.39 +/- 0.23 ml/kg/min). Mean half-life of caffeine in patients with liver disease (23.96 +/- 12.19 h) was significantly higher than in patients with no liver disease (7.25 +/- 3.04 h). No significant differences in distribution volumes were found. Receptor-operator curves (ROC) for plasma clearance and the half-life of elimination of caffeine showed a high diagnostic value. Therefore, the parameters for caffeine biotransformation, i.e. Cl and t1/2, are useful for assessing liver function in the population studied.

Adolescent↗
PubMed1995

Clinical efficacy of intramuscular human interferon-beta vs interferon-alpha 2b for the treatment of chronic hepatitis C.

We have conducted a randomized study to compare the efficacy and tolerance of human interferon (IFN) beta vs recombinant IFN-alpha 2b in patients with chronic active hepatitis C. Forty patients were included: 21 received IFN-alpha (group A) and 19 IFN-beta (group B). IFN was administered intramuscularly at a dose of 6 MU three times a week (tiw) for 2 months (induction phase), followed by 3 MU tiw for 4 months. Clinical, epidemiological and pathological features were similar in the two groups. Normal alanine aminotransferase (ALT) values at the end of treatment was regarded as a response to therapy and the response rate was 57% (12/21) in group A and 5.2% (1/19) in group B (P < 0.01). Both types of IFN induced a significant decrease in mean ALT values by the end of the induction phase (P < 0.01). When the dose was reduced to 3 MU, a marked, but not significant increase in ALT, was seen in group B, whereas no increase was seen in group A. IFN-beta was better tolerated and haematological adverse effects (platelet and leucocyte decrease) were less pronounced with IFN-beta. Hence, human IFN-beta was less effective than IFN-alpha in treating chronic hepatitis C virus (HCV). Doses of IFN-beta of 3 MU intramuscular (IM) tiw were clearly insufficient and it remains to be established whether higher doses of intramuscularly IFN-beta can be useful.

Chronic Disease↗
PubMed1995

Lethality and survival of Klebsiella oxytoca evoked by conjugative IncN group plasmids.

The transmission of plasmid pCU1 (or other IncN group plasmid) into a population of Klebsiella oxytoca cells reduces the viability of the population. A 2,400-bp region adjacent to traA is responsible for this phenotype and includes two regions, called kikA and kikC. Klebsiella cells which received this region and survived were found to acquire a chromosomal mutation which renders them immune to killing even after the plasmid is cured from the cells. To obtain insight into the mode of this apparent lethality, an appropriate pCU1lacZ derivative was constructed. It could be introduced with high efficiency into Klebsiella cells. Analyses of the resultant colonies indicate that the loss of viability is not a consequence of the death of plasmid-free segregants. On the contrary and unlike postsegregational killing by plasmids, cells survived by losing the plasmid or by acquiring, secondarily, a chromosomal mutation which confers immunity to killing.

Base Sequence↗
PubMed1995

Comparative effects of food restriction, fasting, diabetes and thyroidectomy on growth hormone and thyrotropin gene expression in the rat pituitary.

To examine the molecular basis for the decreased pituitary growth hormone (GH) and thyrotropin (TSH) content during restricted feeding, fasting and diabetes, we measured steady-state levels of mRNA for TSH-alpha, TSH-beta and GH in the pituitary from normal rats either fed ad libitum (C), limited to 75%, 50% and 25% (FR75, FR50, FR25, respectively) of ad libitum intake, or deprived of food for 2 and 4 days (F2 and F4, respectively), and also in streptozotocin-diabetic (D) and D insulin-treated animals. The results from these experimental groups were compared with those in thyroidectomized (Tx) rats. Pituitary mRNA was quantified by Northern blot hybridization with cDNA probes specific for rat TSH-alpha, TSH-beta and GH. Although changes in the pituitary GH mRNA during restricted feeding, fasting and diabetes were similar qualitatively to those induced by hypothyroidism, GH mRNA levels in Tx rats (> 10% of C values) were less than in the other experimental groups (p < 0.001). Pituitaries from FR50, FR25 and D rats also contained less GH mRNA than F2 and F4 animals (p < 0.05). Thyroidectomy resulted in a marked increase in both TSH-beta and TSH-alpha mRNAs, the changes in TSH-beta mRNA being greater than those in TSH-alpha mRNA. In contrast, FR50, FR25, F2, F4 and D rats exhibited a decrease in pituitary TSH-beta mRNA (60%, 50%, 35%, 36% and 33%, respectively, of C values; p < 0.01-0.05) and in TSH-alpha mRNA levels (81%, 64%, 46%, 43% and 36%, respectively, of normal values; p < 0.02-0.05), TSH-beta mRNA showing the greater changes.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1995

Cell aggregation and apoptosis induced by hemodialysis membranes.

During hemodialysis, circulating mononuclear cells can be stimulated to different degrees, depending on membrane biocompatibility. Cell activation usually leads to aggregation and proliferation. It may also result in apoptosis if cells are subjected to abnormal activation. This may be the case of cells exposed to bioincompatible hemodialysis membranes. The study presented here evaluates the effects of two hemodialysis membranes, with different degrees of biocompatibility, (Cuprophan (CU; Lundia IC 5N; GAMBRO, Sweden) and polyacrylonitrile (AN69; Biospal 3000S, Hospal, France)) on aggregation and apoptosis of circulating human mononuclear cells and the human mononuclear cell line (THP-1). The results showed that 2-h incubation with CU, a bioincompatible membrane, produces cell aggregation of both peripheral mononuclear cells and THP-1 cells (35% and 54%, respectively). After 48 h of incubation with a CU membrane, apoptotic death was observed in 32% of THP-1 cells and in 45% of normal peripheral mononuclear cells. Neither cell aggregation nor apoptosis was observed after incubation with the AN69 membrane. CU membrane-induced apoptosis was inhibited by Staurosporrin (Sigma, St. Louis, MO) a protein kinase C (PKC)-inhibitor, suggesting that cell apoptosis induced by the CU membrane is mediated by a PKC-dependent cell activation. Furthermore, cell prestimulation with phorbol 12-myristate 13-acetate, an activator of PKC, results in a increase in the percentage of THP-1 cell death by apoptosis after CU exposure (53%). Our study indicates that CU membranes induce mononuclear cell activation, leading to cell apoptosis.

Acrylic Resins↗
PubMed1995

Tuberculous peritonitis: diagnostic value of ascitic fluid pH and lactate.

BACKGROUND: The analytical pattern of ascitic fluid in peritoneal tuberculosis is frequently similar to that found in other causes of ascites. The diagnostic value of the ascitic fluid pH and lactate in cases of tuberculous peritonitis has not yet been established. METHODS: Ascitic fluid pH, lactate, total proteins, cell count, lactate dehydrogenase, glucose, and their blood-ascitic gradients were determined in 10 patients with tuberculous peritonitis (group I). These results were compared with those obtained from 40 patients with cirrhotic sterile ascites (group II), 16 patients with spontaneous bacterial peritonitis (group III), and 18 patients with malignant ascites (group IV). RESULTS: A decreased pH and an elevated lactate level in ascitic fluid were found in patients in group I in comparison with those in group II (p < 0.001). No significant differences were found between group I and groups III and IV. The arterial blood-ascitic fluid pH gradient was more than 0.10 (p < 0.001), and the ascitic fluid-serum lactate gradient was greater than 15 mg/dl (p < 0.001) in group I when compared with group II. No significant differences were found between group I and groups III and IV. CONCLUSIONS: Ascitic fluid pH and lactate are useful markers in differentiating tuberculous peritonitis from cirrhotic sterile ascites. However, these variables lack specificity, as they are also decreased and increased, respectively, in cases of malignant ascites and spontaneous bacterial peritonitis.

Adult↗
PubMed1995

Epidemiology of hepatitis D virus infection: changes in the last 14 years.

To calculate the prevalence of hepatitis D virus (HDV) superinfection, antibody to HDV (anti-HD) was tested on admission in 696 hepatitis B virus (HBV) chronic carriers diagnosed between 1979 and 1992. Anti-HD was positive in 67 patients (9.6%), and it was more frequently detected in i.v. drug abusers (IVDA) (59/74, 79.7%) than in non-IVDA (8/622, 1.3%) (p = 0.0001). The prevalence of anti-HD was higher in HBV chronic carriers diagnosed between 1979 and 1985 (33/219, 15.1%) than in those diagnosed from 1986 to 1992 (34/477, 7.1%) (p < 0.001). However, these figures were not different when IVDA were analyzed alone; 29/34 (85%) and 30/40 (75%) (p = 0.4) IVDA diagnosed in both time frames were anti-HD-positive. Four hundred and thirty anti-HD-negative HBV carriers were prospectively followed, and serial determinations of anti-HD were made. Seroconversion to anti-HD was observed in only six patients (1.4%), and again the rate of seroconversion was higher in IVDA (5/10, 50%) than in non-IVDA (1/420, 0.2%) (p < 0.0001). These findings show that IVDA HBV chronic carriers are still an extremely high risk group for HDV superinfection in Spain and that this virus has little penetrance in other epidemiological categories of HBV carriers.

Adult↗