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Biomedical subjects

R Vidal

Publications and source records attributed to R Vidal.

At least 109 records · Page 6Linked to original sources
PubMed1997

Determination of total and pancreatic alpha-amylase in human serum with 2-chloro-4-nitrophenyl-alpha-D-maltotrioside as substrate.

A reagent and assay conditions for the determination of the catalytic concentration of alpha-amylase (E.C. 3.2.1.1) in serum with 2-chloro-4-nitrophenyl-alpha-D-maltotrioside as substrate are described. The selected reaction mixture contains 50 mmol/l 2-(N-morpholino)ethanesulfonic acid buffer at pH 6.1 (37 degrees C), 300 mmol/l sodium chloride, 5 mmol/l calcium chloride and 450 mmol/l potassium thiocyanate. The described method is suitable for the measurement of total as well as pancreatic alpha-amylase by including antibodies against the salivary isoenzyme. The method shows the absence of a lag phase period, is sensitive and precise, has a large analytical range and is free from interference by hemoglobin, bilirubin and triglycerides. Comparative studies showed good correlation with other well established methods.

Buffers↗
PubMed1997

[A contagiousness study in 3071 familial contacts of tuberculosis patients].

BACKGROUND: The study of contacts of patients with tuberculosis is an important preventive measure which helps to identify the risk factors for contagion, to detect new cases of the disease early and to break the epidemiological chain of transmission. MATERIAL AND METHOD: Three thousand and seventy-one contacts of 635 patients with tuberculosis were studied in our department over a period of 6 years. With the aid of uni- and multivariate analyses we established the importance of different factors in the appearance of tuberculous disease and infection in contacts. RESULTS: There were 1,341 tuberculin positive contacts (44%). The proportion increased in relation to the degree of the relationship and the bacillary density of the index case. A hundred and seventy-six new cases of tuberculosis were diagnosed among the contacts (5.7%). To study the risk factors for contagion, we analyzed the characteristics of 322 patients with positive sputum smears and their 1,623 contacts; 124 new cases were diagnosed among them (124/176; 70%). The most important factors for contagion in the multivariate analysis were the closer relationship (odds ratio [OR] = 8.32; confidence interval [Cl] 95% = 3.9-17.6), greater TST reaction of contacts (OR = 4.43; Cl 95% = 2.5-7.7), presence of more than 10 bacilli per microscopic field in the sputum samples of the index case (OR = 1.97; Cl 95% = 1.1-3.3), male contacts (OR = 1.86; Cl 95% = 1.2-2.7) and those younger than 15 years (OR = 1.58; Cl 95% = 1.01-2.45). Conversely, the sex of the index case and the history of previous tuberculosis in contacts did not influence the contagion. CONCLUSIONS: The study of contacts offers a high yield in the diagnosis of new tuberculosis cases, because the incidence of the disease is much higher than that of the general population. Moreover, it allows the detection of newly infected subjects in whom the application of chemoprophylaxis prevents the development of the disease, and thus the epidemiologic chain of transmission is broken.

Adolescent↗
PubMed1997

Life-threatening toxicity of oral tegafur-uracil (UFT) plus leucovorin.

UFT. a a combination of tegafur and uracil, is increasingly used in the treatment of gastrointestinal malignancies. We report on a life-threatening toxicity observed in a 74-year-old female while undergoing adjuvant treatment with oral UFT plus leucovorm for adenocarcinoma of the rectum. The patient developed grade 4 thrombocytopenia, grade 4 neutropenia, grade 3 infection, grade 3 neurotoxicity and grade 2 cutaneous toxicity. This oral double-agent regimen should be used with caution in the adjuvant treatment of elderly patients with gastro-intestinal malignancies.

Administration, Oral↗
PubMed1997

Amino-terminal identity of co-existent amyloid and non-amyloid immunoglobulin kappa light chain deposits. A human disease to study alterations of protein conformation.

Tissue deposition of monoclonal immunoglobulin light chains is a serious complication in some patients with B cell proliferative disorders. The deposits are typically fibrillar and Congophilic in amyloid (AL) and non-fibrillar and Congophobic in light chain deposition disease (LCDD), and rarely coexist in the same patient. From post-mortem tissue of an individual with fibrillar and non-fibrillar kappa light chain deposits in different sites, we separately extracted and analysed biochemically and immunochemically the non-amyloid deposits from isolated glomeruli, the amyloid from isolated renal arteries and the amyloid from myocardium in which the only deposits were amyloid restricted to mural arteries. Western blotting analysis of both the extracted amyloid and the non-amyloid deposits demonstrated 25-kD bands immunoreactive with anti-kappa antibody, and the identity of the N-terminal amino acid sequences that belong to the variable region kappaIV light chain subgroup. This is the first human disease in which antigenically similar but morphologically different deposits have been separately biochemically analysed. We propose that combined LCDD and AL is an ideal human disease to study the relationships and the factors that influence the conversion of non-amyloidogenic to amyloidogenic conformations.

Aged↗
PubMed1997

Complex polysaccharides as PCR inhibitors in feces: Helicobacter pylori model.

A model was developed to study inhibitors present in feces which prevent the use of PCR for the detection of Helicobacter pylori. A DNA fragment amplified with the same primers as H. pylori was used to spike samples before extraction by a modified QIAamp tissue method. Inhibitors, separated on an Ultrogel AcA44 column, were characterized. Inhibitors in feces are complex polysaccharides possibly originating from vegetable material in the diet.

Feces↗
PubMed1997

Increased risk of tuberculosis transmission in families with microepidemics.

In the present study, we analysed: 1) prevalence of TB infection and incidence of disease among family contacts of a cohort of patients with TB; 2) differential characteristics of families with microepidemics and families with < or = 1 new case of TB; and 3) efficacy of chemoprophylaxis in this group of contacts. Three thousand and seventy one family contacts of 635 patients with TB were studied. The study consisted of tuberculin skin testing and chest radiography in all cases, and bacteriological studies when active disease was suspected. Contacts were classified as belonging to: families with microepidemics (FME) (those with > or = 2 new cases of TB); families with one new case; and families with with no new cases. Chemoprophylaxis was prescribed in contacts following standard recommendations; all were followed up for 12-18 months. Rates of TB infection and disease among families, as well as the incidence of TB disease between those compliant and noncompliant with chemoprophylaxis were compared. Among the 3,071 contacts, 1,264 (41%) were infected and 176 (6%) had TB. Twenty two families with FME (3%) yielded 55 new cases of TB. The prevalence of infection (excluding the TB cases) was 80% in families with FME, 52% in families with one new case, and 41% in families with no new case (odds ratio (OR) 3.7; 95% confidence interval (95% CI) 2.1-6.5). Sputum smears were positive in 53% of cases in FME and 24% in non-FME families (OR 3.4; 95% CI 1.7-6.5). Bronchial sample cultures were positive in 84% of patients from FME families but in only 40% of those from non-FME families (OR 7.5; 95% CI 3.6-15.8). Chemoprophylaxis was prescribed in 356 contacts, of whom 296 complied and generated only one new case of TB, whilst there were 13 new cases among the 60 who did not comply (OR 81.6; 95% CI 26.7-248.7). This study showed the prevalence of infection and incidence of tuberculosis among family contacts of patients with newly diagnosed tuberculosis to be very high. A small number of families with microepidemics accounted for most new cases of tuberculosis, which were also more infectious. The extremely high risk of transmission in these families, together with the proven efficacy of chemoprophylaxis, justifies prescription of chemoprophylaxis to all their members, regardless of age.

Adult↗
PubMed1997

Growth of methylaminotrophic, acetotrophic and hydrogenotrophic methanogenic bacteria on artificial supports.

The efficiency of organic matter degradation in attached biomass reactors depends on the suitable selection of artificial support for the retention of bacterial communities. We have studied the growth on glass and clay beads of methylaminotrophic, acetotrophic and hydrogenotrophic methanogenic bacterial communities isolated from anaerobic reactors. Bacterial counts were performed by the standard MPN technique. Experiments were performed in 50 ml vials for 12 days at 35 degrees C. Increase in the counts of methylaminotrophic and hydrogenotrophic methanogens occurred on both glass and clay beads. The latter support material also stimulated the growth rate of methylaminotrophic methanogens.

Aluminum Silicates↗
PubMed1997

Effect of imipenem and sulbactam on sessile cells of Acinetobacter baumannii growing in biofilm.

The effect of the age of biofilms formed by Acinetobacter baumannii on the activity of sulbactam and imipenem on sessile cells was investigated. Against cells of young biofilms both antibiotics were rapidly bactericidal. As the biofilm aged, sulbactam lost most of its activity, but imipenem continued to be bactericidal to some extent. This fact probably reflects the ability of imipenem to exert bactericidal activity on slow-growing bacteria.

Acinetobacter↗
PubMed1996

Alzheimer's presenilin 1 gene expression in platelets and megakaryocytes. Identification of a novel splice variant.

The presenilin 1 (PS1) gene located on chromosome 14 has been linked with the majority of early-onset FAD. The normal biological role of PS1 as well as the mechanism by which mutations in PS1 cause FAD remains unknown. PS1 expression in platelets and the Dami megakaryocytic cell line was examined by Western blot analysis and RT-PCR. Using an anti-N-terminus PS1 antibody we detected PS1 immunoreactive bands of 44, 32 and 27 kDa in both cell types. After RT-PCR we observed that platelets and megakaryocytes carry at least four different PS1 transcripts. One of them is a novel PS1 splice variant that lacks the coding sequence for exon 10 resulting in a shorter 409 amino acid protein.

Alternative Splicing↗
PubMed1996

[Study of the frequency of different phenotypes of alpha-1-antitrypsin in a population of Barcelona].

BACKGROUND: Severe alpha-1-antitrypsin (AAT) deficiency is caused by homozygous inheritance of gene Z, and is associated with a high risk of developing pulmonary emphysema. Determination of frequencies of different genes associated with the deficiency (especially S and Z) gives a clue to estimate the number of individuals homozygous PiZZ, carrying a high risk for pulmonary disease, in any given population. PATIENTS AND METHODS: Pi phenotypes of 440 healthy individuals were determined by means of isoelectrofocusing in polyacrylamide gel. Seric values of AAT were determined by immunonephelometry. Mean age of participants was 30 years (range 18-49 yrs.). Results are compared with other published series. RESULTS: Distribution of phenotypes was: PiMM 333 individuals (75%), PiMS 84 (19%), PiMZ 14 (3%), PiSS 4 (0.9%), PiM 3 (0.6%), PiMF 1 (0.2%), PiMP 1 (0.2%). The corresponding gene frequencies were Pi*M 87%, Pi*S 10.4%, and Pi*Z 1.5%. Normal values of AAT (phenotype PiMM) established in our laboratory were 116-232 mg/dl (21-41 micromol/I) (mean +/- 2 SD). According to Hardy-Weinberger equation, expected frequency of PiZZ individuals in our area would be 225 per million. CONCLUSIONS: The frequency of Z gen individuals observed in our study is one of the highest in the Iberian Peninsula, but lower than the frequency in northern Europe. According to these results, AAT deficiency (PiZZ) is not a rare condition in contrast with the small number of patients diagnosed. The gen frequency of the S variant is higher than that of the rest of Europe, and similar to others found in some Spanish populations.

Adolescent↗
PubMed1996

PrP27-30 is a normal soluble prion protein fragment released by human platelets.

Prion diseases are neurodegenerative disorders characterized by the accumulation of abnormal isoforms of prion protein (PrPSc) in the central nervous system. PrPSc isoforms differ from their normal homologue (PrPC), in that they possess increased beta-sheet conformation, are partially protease resistant and may be associated with amyloid deposition. Amyloid proteins are thought to derive from soluble precursors or fragments thereof, present in biological fluids, which in the disease state undergo conformational change leading to aggregation and deposition in target tissues. We report here that platelets carry PrP mRNA and release PrPC, a sialoglycoprotein bound to the cell surface by a glycosylphosphatidylinositol (GPI) anchor. Soluble PrPC, and a N-terminal truncated PrPC isoform starting at position 90 are secreted by resting and agonist-stimulated platelets and are detectable after partial deglycosylation of releasates. N-terminal sequence analysis of the soluble 27-30 kDa isoform, GQGGGTHSQ(W)NKP, revealed homology to scrapie PrP27-30, the protease resistant core derived from PrPSc. These findings indicate that in addition to PrPC, platelets process a soluble PrP27-30 isoform. Whether this isoform can be converted in scrapie PrP27-30 remains to be determined.

Amino Acid Sequence↗
PubMed1996

Apolipoprotein E and amyloidogenesis.

Alzheimer's amyloid beta-protein (A beta) is a modified, pathogenic form of a constitutive host protein, soluble amyloid beta-protein (sA beta). Both are conformational isomers encoded by the gene for the beta-amyloid precursor protein (APP), located on chromosome 21. sA beta and A beta have identical sequence but are thought to differ in their secondary structure and physicochemical properties, hence they are conformational isomers. sA beta is easily degraded, while A beta is particularly resistant. A beta has a high beta-pleated sheet content, while sA beta is thought to be more random-coil and/or alpha-helical. A beta, unlike sA beta, adopts an amyloidogenic conformation, forms aggregates and gives rise to fibrils. Most early-onset forms of Alzheimer's disease (AD) have been linked to mutations of the presenilin 1, presenilin 2 or APP genes, located on chromosomes 14, 1 and 21, respectively. Their relationship to amyloidogenesis is being investigated. On the other hand, the major risk factor for the most common form, sporadic and familial late-onset AD, is the presence of the apoE epsilon 4 allele. Recent studies have shown that a 10 kDa C-terminal fragment of apoE is complexed to A beta in neuritic plaques and that apoE isoforms can modulate amyloid formation in vitro. Moreover, thrombin cleavage of apoE generates a similar C-terminal fragment that can form amyloid-like fibrils. Thus neuritic plaques may contain both A beta and apoE amyloid fibrils. AD can be neuropathologically defined by the presence of several interacting proteins that can adopt an amyloidogenic conformation. This has led us to hypothesize that in AD, amyloidosis may be reactive rather than causative.

Alzheimer Disease↗
PubMed1996

Fibrillary glomerulonephritis related to serum fibrillar immunoglobulin-fibronectin complexes.

Fibrillary glomerulonephritis is a disease of uncertain origin and pathogenesis characterized by nonamyloidotic fibrils in glomeruli. We report immunohistological, immunochemical, and biochemical studies of a serum fibrillar cryoprecipitate obtained from a patient with fibrillary glomerulonephritis, that formed on prolonged storage at 4 degrees C. By Western blot and amino acid sequence analysis, the cryoprecipitated fibril components consisted of immunoglobulins, heavy chains gamma and mu, light chains kappa and lambda, and fibronectin, similar to the proteins identified by immunofluorescence and immunoelectron microscopy in the glomerular fibrils. These findings support the hypothesis that serum precursors may be the source of the fibrillar deposits and suggest a role for immunoglobulin-fibronectin complexes in the pathogenesis of fibrillary glomerulonephritis.

Antigen-Antibody Complex↗
PubMed1996

The influence of intravenous drug use and HIV infection in the transmission of tuberculosis.

OBJECTIVE: To investigate whether smear-positive pulmonary tuberculosis (TB) patients present a different risk of TB transmission according to their HIV status, in an area where the majority of HIV-infected patients studied were intravenous drug users (IVDU). METHODS: A case-control study was performed on smear-positive pulmonary TB patients diagnosed between 1990 and 1993 for whom a contact study had been performed. Patients with and without HIV infection were matched by age (+/- 3 years), sex and hospital of diagnosis. A micro-epidemic was defined if two or more secondary cases were detected from the same index case. Data were analysed comparing the percentage of contacts with TB in both groups. RESULTS: Thirty-six secondary cases were detected in 436 contacts of 124 HIV-infected TB patients, whereas only 24 were identified in 624 contacts of 124 HIV-seronegative TB patients [odds ratio (OR), 2.14; 95% confidence interval (CI), 1.22-3.77; P = 0.004]. Comparing the contacts of HIV-infected patients, 34 secondary cases of TB were detected in 371 contacts of 97 IVDU, whereas only two cases were detected in 85 contacts of 27 non-IVDU (OR, 4.19; 95% CI, 1.09-15.95). HIV-seropositive index cases were observed to cause more micro-epidemics than seronegative cases (eight versus four), indicating that micro-epidemic cases were more frequent in the contacts of HIV-infected subjects (27 out of 36 versus 10 out of 24; OR, 1.41; 95% CI, 1.41-12.49; P = 0.009). All index cases in eight micro-epidemics were HIV-seropositive IVDU, whereas only four micro-epidemics were generated by HIV-seronegative subjects, none of whom were IVDU. CONCLUSIONS: Smear-positive pulmonary TB patients were more likely to transmit TB if they were HIV-infected, as evidenced by the role of IVDU in generating micro-epidemics.

Adult↗