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Biomedical subjects

A Páez

Publications and source records attributed to A Páez.

At least 19 recordsLinked to original sources
PubMed2005

Molecular epidemiology of rabies in northern Colombia 1994-2003. Evidence for human and fox rabies associated with dogs.

During the period 2000-2003, wild grey foxes (Urocyon cinereoargenteus) in northern Colombia became infected with rabies. In order to derive phylogenetic relationships between rabies viruses isolated in foxes, dogs and humans in this region, 902 nt cDNA fragments containing the G-L intergenic region and encoding the cytoplasmic domain of protein G and a fragment of protein L were obtained by RT-PCR, sequenced and compared. Phylogenetic analysis showed that rabies viruses isolated in foxes, dogs and humans belonged to a single genetic variant. Speculative analysis together with epidemiological data indicated that rabies in foxes may have been due to contact with rabid dogs. Rabies transmission between dogs, wild foxes and humans may happen in natural conditions in northern Colombia. This finding is the first to suggest dog-to-fox rabies transmission in South America, and provides another example of dog rabies variants being able to successfully colonize wildlife hosts.

Animals↗
PubMed2003

The Spanish contribution to the European Randomized Study of Screening for Prostate Cancer.

OBJECTIVE: To summarize the experience of the Spanish participation in the European Randomized Study of Screening for Prostate Cancer (ERSPC). METHODS: In this study men aged 45-70 years were randomized (1:1) and allocated to one of two arms: screening, with an indication for transrectal ultrasonography (TRUS) and sextant prostate biopsy when the serum prostate-specific antigen (PSA) level was >4 ng/mL (until May 1998) and from then when the PSA was >2.9 ng/mL; and a control group (no diagnostic tests). The findings from a digital rectal examination were not considered as a criterion for biopsy. When the serum PSA was above the threshold levels, biopsy-negative men were invited again after a year ('early recall'). The next (second) screening round was programmed for the rest of participants after a 4-year interval. Cancer-specific mortality was recorded and compared in both groups. RESULTS: In all, 4278 men were recruited (2416 in the screening group and 1862 in the control group). The recruitment phase was closed in June 1999. During the first screening round 40 cancers were detected; the detection rate was then 1.7% and 4.15 biopsies were needed to detect each cancer. The clinical stage was localized in 88.6% and regional or metastatic in 11.4%. Within the first round, 17 more cancers were detected at early recall attendance. During the second screening round 14 cancers were found, giving a detection rate of 1.9%; 17 more cancers were also diagnosed outside the screening programme (contamination), seven in the screening group and 10 in the control group. Until February 2003, 85 participants had died (53 screened and 32 control) but none from prostate cancer. CONCLUSIONS: Cancer detection rates can be increased with further early recalls; the clinical stage was localized in an important proportion of cancers detected.

Age of Onset↗
PubMed2003

Four-year prostate-specific antigen progression in the non-cancer population of the European Randomized Study of Screening for Prostate Cancer.

OBJECTIVE: To determine the rate of conversion of prostate-specific antigen (PSA) to values of > 4 ng/mL in a normal male population. PATIENTS AND METHODS: In men with an initial PSA level of < 4 ng/mL the probability of having a PSA of > or = 4 ng/mL and its relationship with the age at first PSA test, baseline PSA level and time to the determination was evaluated. Statistical methods were used to correct for the within-subject variability across many PSA determinations. RESULTS: In all, 45433 PSA tests in 21169 men with an initial PSA of < 4 ng/mL were available. Overall, in 960 men (4.5%) the PSA level changed to > or = 4 ng/mL. The lowest chance was for men aged < 55 years with an initial PSA of < 1 ng/mL and a new PSA determination during the first 18 months (0.952 conversions per 1000 men) while the highest was for men aged < 55 years with an initial PSA level of > 2.5 ng/mL (395 conversions per 1000 men). There was a significant and independent relationship between conversion and the interval between determinations, with conversion being 3.33 times more frequent during 18-42 months than with the reference category (< 18 months) and 5.23 times more frequent during > 42 months. The probability of conversion independently increased by 3 lambda for every additional year of age. Every unit of basal PSA multiplied by 6.48 the probability of conversion. CONCLUSIONS: The risk for conversion to a PSA of > or = 4 ng/mL can be anticipated from the patient's age and initial PSA level. Re-screening before 4 years after the first round can be useless for men with an initial PSA of < 1 ng/mL. Four-year intervals could be inadequate for men with an initial PSA of > 2.5 ng/mL if conversion to > 4 ng/mL is to be avoided.

Adult↗
PubMed2002

The clinical utility of the prostate specific membrane antigen reverse-transcription/polymerase chain reaction to detect circulating prostate cells: an analysis in healthy men and women.

OBJECTIVE: To evaluate the overall specificity of nested reverse transcriptase-polymerase chain reaction (RT-PCR) to detect prostate-specific membrane antigen (PSM) mRNA in peripheral blood samples of healthy donors. SUBJECTS AND METHODS: Peripheral blood samples were taken from 60 healthy blood-donors (30 men and 30 women aged < 50 years) and analysed for PSM-mRNA using nested RT-PCR (in 'hot-start' conditions and confirmed using nested EcoRI restriction enzyme). Intron-spanning primer pairs specific for human PSM were deduced from the GenBank sequence (M99487) using gene software. The outer primer pair for PSM was: fwd: 1368 5'-TCACCGGGACTCATGGGTGT-3'; reverse: 1860 5'-GCCTGAAGCAATTCCAAGTCGG-3'. Inner primer pair for PSM was: fwd: 1480 5'-AAGGAAGGGTGGAGACCTAG-3'; reverse: 5-ACTGAACTCTGGGGAAGGAC-3'. The integrity of cDNAs was checked using primer pairs specific for the housekeeping gene beta-actin. The specificity and false-positive rate were calculated assuming that the underlying prostate cancer incidence was nil. RESULTS: The first PCR was negative for all samples (100% specificity; 0% false-positive rate). The nested PCR detected 23 positive samples (23/60, 38%) with an overall specificity of 62% (false positive rate, 38%). CONCLUSION: Nested RT-PCR of PSM-mRNA in peripheral blood is highly unspecific. Its clinical utility in the management of prostate cancer must be low. Further development is needed of quantitative RT-PCR, primers that identify prostatic PSM or another prostate-specific marker gene to differentiate PSM mRNA from circulating prostate cells and from non-prostatic tissues.

Adult↗
PubMed2002

Polyphenols in red wine inhibit the proliferation and induce apoptosis of LNCaP cells.

OBJECTIVE: To assess the effect of five polyphenol constituents of red wine (quercetin, morin, rutin, gallic acid and tannic acid) on the proliferation of LNCaP cells, and to quantify the extent of apoptosis with each polyphenol. MATERIALS AND METHODS: LNCaP cells (500) were cultured in microtitre plates and treated with gallic acid, tannic acid, quercetin (1, 5 and 10 micromol/L), rutin and morin (25, 50 and 75 micromol/L). A colorimetric immunoassay was then used to determine the extent of proliferation at 24, 48, 72 and 96 h, and a cell-death detection assay to assess apoptosis at 24, 48 and 72 h. RESULTS: Gallic and tannic acid (5 and 10 micromol/L), morin (50 and 75 micromol/L), quercetin (5 and 10 micromol/L) and rutin (50 and 75 micromol/L) all significantly inhibited (P<0.05) cell proliferation compared with the control. Apoptotic indexes were significantly greater (P<0.01) in the presence of gallic (5 and 10 micromol/L) and tannic acid (5 and 10 micromol/L), and rutin (75 micromol/L, P<0.05) than in the control. The apoptotic effect of morin (75 micromol/L), although significant (P<0.01), only appeared at 72 h. Conversely, while significant (P<0.05) quercetin (5 and 10 micromol/L) had a transient (first 48 h) apoptotic effect compared with the control. CONCLUSION: Quercetin, rutin, morin, gallic acid and tannic acid inhibited the growth of LNCaP cells at different concentrations, and induced apoptosis. The results provide a strong rationale for studying the in vivo effects of these compounds.

Apoptosis↗
PubMed2000

Detecting circulating prostate cells in patients with clinically localized prostate cancer: clinical implications for molecular staging.

OBJECTIVE: To evaluate the clinical utility of using the reverse transcriptase-polymerase chain reaction (RT-PCR) to detect prostate-specific antigen (PSA) mRNA in peripheral blood samples from patients with prostate cancer, as a predictor of extraprostatic disease, and to assess any correlations with known predictive markers of this condition. PATIENTS AND METHODS: Immediately before radical prostatectomy, peripheral blood samples were taken from 25 men with clinically localized prostate cancer and analysed for PSA mRNA using RT-PCR (in 'hot-start' conditions and confirmed using ClaI restriction enzyme). The relationships between PSA mRNA positivity, pathological and clinical features were analysed; PSA mRNA positivity, PSA level and biopsy Gleason score were then compared as predictors of extraprostatic disease. RESULTS: There was no relationship between PSA mRNA positivity and pathological stage (pT2 or pT3), and no association between PSA mRNA positivity and serum PSA level, PSA density, the findings on a digital rectal examination or transrectal ultrasonography, and perineural invasion in the prostatic biopsy. However, there was a significant correlation between the Gleason score of the preoperative biopsy and PSA mRNA positivity. The best predictors of extraprostatic disease were the biopsy Gleason score and the PSA level. CONCLUSION: There was no significant advantage in using the RT-PCR assay of PSA mRNA before surgery to stage prostate cancer and to discriminate between organ-confined and extraprostatic neoplasms.

Adult↗
PubMed1999

Secretion of IFN-gamma by bovine peripheral blood mononuclear cells stimulated with Mycobacterium bovis protein fractions obtained by isoelectric-focusing.

Due to the complexity and variety of biological effects found in Mycobacterium bovis (M. bovis) proteins analyzed solely on a molecular weight (MW) basis, we approached the purification of M. bovis proteins through their isoelectric point (pI). Twenty M. bovis culture filtrate protein extract (CFPE) isoelectric focused (IEF) protein fractions, confined between pI3 and 10, were isolated. The MW of the major proteins isolated in the various fractions correlated with protein already reported 14-, 18-, 20-, 25-, 31-, 38-, 45-, 64-, 67- and 70 kDa by SDS-PAGE. Since several different pI fractions showed proteins of the same MW we tested the ability of all IEF fractions to stimulate interferon-gamma (IFN-gamma) production by peripheral blood mononuclear cells (PBMC) isolated from cattle with well defined M. bovis tuberculosis (TB) infection. In animals with few lesions IFN-gamma inductive IEF fractions were in the acid range. As the number of lesions increased, neutral fractions were also inductive. Some fractions with relatively few proteins induced as much IFN-gamma production as others with abundant proteins. None of the 20 IEF fractions enhanced IFN-gamma production by anergic cells. We conclude that IFN-gamma production in diseased animals is induced mainly by acidic mycobacterial proteins and that the response towards these proteins is enhanced as the disease progresses, what coincides with higher PPD reactivity. However, the IFN-gamma production in anergic status was severely affected. We found that this cytokine production is spontaneous and antigen-independent.

Animals↗
PubMed1999

Characterization of von Willebrand factor in primary pulmonary hypertension.

The aim of this study was to determine the value of von Willebrand factor (vWF), a well-characterized endothelial cell protein secretion, as a marker for prognosis in patients with primary pulmonary hypertension (PPH). Venous and arterial blood samples were obtained from 18 clinically diagnosed PPH patients and 12 case controls matched for age and sex. Plasma vWF antigen was determined by enzyme-linked immunosorbent assay (ELISA). The patients' multimeric vWF pattern was analyzed by sodium dodecylsulfate (SDS)-agarose-acrylamide electrophoresis, Western blot, and densitometric analysis. vWF sialic acid content was determined by a lectin-based ELISA. The PPH patients showed a higher content of vWF antigen in venous (P = 0.0026) and arterial (P = 0.0094) blood samples than controls. The mean vWF sialic acid content of the PPH patients corresponded to 37.7% of the mean value for the control group. On the basis of the hemodynamic response to vasodilator trial, the PPH patients were grouped as responders or nonresponders. The latter group showed a significantly higher plasma vWF antigen antecubital vein/radial artery ratio, an increased number of unusually large vWF multimers, and a diminished content of vWF sialic acid in comparison with the first group. We believe that our results establish the nature of vWF alterations that are related to endothelial cell damage in patients with primary pulmonary hypertension and that this could be of value when establishing the prognosis in this group of patients.

Adrenergic beta-Agonists↗
PubMed1999

Final results of a screening campaign for prostate cancer.

OBJECTIVE: To detect curable prostate cancer in a male Spanish population. The results of screening 2,576 men are reported. PATIENTS AND METHODS: Patients underwent digital rectal examination (DRE) and serum prostate-specific antigen (PSA) determination. Any patient with suspicious DRE or PSA > 4 ng/ml was further evaluated with transrectal ultrasonography (TRUS) and biopsy. The sensitivity, specificity and predictive value of the tests or combinations of tests were determined. RESULTS: Mean age was 59.9 years (median 58 years). Ninety-four patients (3.6%) had abnormal DRE while PSA was > 4 ng/ml in 169 patients (6.5% of the total). We needed 6.8 biopsies to prove one cancer. PSA had the highest sensitivity (93%), whereas DRE had the highest specificity (97%). The positive predictive value rose to 78.9% when both DRE and PSA were abnormal. Clinically advanced tumor stages (> or = T3) were commoner (39.4%) than in similar series. CONCLUSIONS: PSA should be the first diagnostic test in a screening program for prostate cancer. Neither DRE nor TRUS are necessary in patients with PSA < 4 ng/ml. In the light of our findings, we cannot encourage screening programs for prostate cancer for the time being.

Aged↗
PubMed1999

Reliability of the routine cytological diagnosis in bladder cancer.

OBJECTIVES: To establish the reliability of three cytopathologists for cytological diagnosis of primary bladder tumors. METHODS: Preoperative voided urine specimens of 71 patients with bladder cancer and 55 noncancer controls were retrospectively and blindly reviewed by 3 independent cytologists, and their results compared. The estimation of the interobserver agreement was calculated using the weighted kappa coefficient. A multivariate analysis was carried out to identify the factors associated with the disagreement between the three observers. The sensitivity and specificity for each of the participants was calculated in order to clearly identify the origin of the disagreement, in terms of the performance of the diagnostic test in the hands of each observer. A comparison of the overall diagnostic performance was made by plotting sensitivity versus 1-specificity. RESULTS: The weighted kappa coefficient among the 3 observers was 0.46. The multivariate analysis did not identify any variable that could have caused such disagreement. Vast differences in sensitivity and specificity were detected between observer 1 (sens. 0.90, spec. 0.45) and observers 2 (sens. 0.67, spec. 0.72) and 3 (sens. 0.71, spec. 0.80), but the overall diagnostic performance (sensitivity vs. 1-specificity) was superimposable in the 3 cases (p = NS). CONCLUSIONS: Simple, reproducible and agreed-on-diagnostic criteria should be established to yield reliable results in a group of cytologists. The consideration of individual diagnostic performances can give a false idea of homogeneity between observers. In this field, concordance analysis makes quality control reliable and should be a routine procedure of any pathology department.

Carcinoma, Transitional Cell↗
PubMed1998

Identification of major glycoconjugates from Mycobacterium bovis culture filtrate by biotin-hydrazide labeling.

To identify Mycobacterium bovis glycoproteins, carbohydrates present in a delipidized M. bovis culture filtrate protein extract were biotin-hydrazide labeled. 11 carbohydrate-containing protein with a molecular weight of 15-, 19-, 25-, 32-, 35-, 39-, 42-, 48-, 52-, 58-, and 62-kDa were detected. The 52- and 32-kDa protein were deglycosylated by endoglycosidase-F.

Bacterial Proteins↗
PubMed1998

Role of autonomic innervation in rat prostatic structure maintenance: a morphometric analysis.

PURPOSE: To analyze the effects of major pelvic ganglion (MPG) excision on the structure of rat prostate. MATERIALS AND METHODS: We studied 80 Sprague-Dawley rats (300-350 gm. weight). Forty-two were anesthetized and the right MPG excised. After 28-30 days, the same-side prostatic ventral lobe (VL) was obtained for macroscopic, light (LM), and transmission electron microscopy (TEM) evaluation. A computerized morphometric analysis was performed on epithelial and muscle cells. Results were compared with 38 right VL of non-operated, same-aged rats. RESULTS: A 36.6% reduction (0.14 gm.) of VL fresh weight was found in the denervated group (p <0.001). Mean tissue proportions observed in the LM study were 27.9% (epithelial), 48.3% (stromal), and 51.8% (glandular) in the non-operated group, versus 14.8% (p <0.001), 55.7%, and 44.4% (not significant) respectively, after MPG excision. No difference was found regarding the vascular pattern. In the denervated rats, TEM analysis found a significant reduction in total and supranuclear cell height (change in cell polarity), as well as in cytoplasm, Golgi and endoplasmic reticulum areas. Secretory granule count, total area (p <0.001), and density of apical microvilli were also reduced. On the other hand, only an increase in the area of cytoplasm ribosomal aggregates was detected in the smooth muscle cell analysis. CONCLUSIONS: Our study demonstrated a rat prostatic VL atrophy in the denervated side, due to a shrinkage in the epithelial component of the gland. Ultrastructural findings also suggest an overall decrease of epithelial cell secretory activity. Finally, the increase of ribosomal aggregates found in stromal smooth muscle could reflect an activation of these cells after denervation.

Animals↗
PubMed1995

Plasmodium falciparum: characterization of a 0.7-kbp, moderately repetitive sequence.

A 692-bp-long repetitive sequence of Plasmodium falciparum was cloned. Two contiguous repeats were sequenced. The homology between them was 85%, the differences being due only to base replacements. The sequence was found 60 times repeated in the genome and was detected in 11 of 14 chromosomes. When used as a probe, the cloned fragment detected the parasite with the same sensitivity the 21-bp repeat (pRepHind) did. PCR amplification detected 0.02 pg of DNA, equivalent to a single parasite, in strains from America, Asia, and Africa. The restriction patterns were polymorphic and different among the strains. Analysis of lambda EMBL clones that contain the repetitive sequence confirms that it is present in various genomic contexts and is located subtelomerically.

Animals↗
PubMed1995

Purification of a N-acetyl-D-galactosamine specific lectin from the orchid Laelia autumnalis.

From the pseudobulbs of the orchid L. autumnalis a lectin was purified on immobilized porcine mucin with A + H blood group substance. This lectin is a dimeric glycoprotein of M(r) 12,000 with an Sw,20 of 2.2, showing haemagglutinating activity directed mainly to human A1 desialylated erythrocytes. The lectin possesses sugar specificity for N-acetyl-D-galactosamine and also shows high specificity for glycoproteins containing the T (galactose beta 1,3GA1NAc alpha 1,0 Ser/Thr) or the Tn antigen (GalNAc alpha 1,0 Ser/Thr).

ABO Blood-Group System↗
PubMed1995

[Abundant erythroblastic islands in bone marrow aspirate in a case of polycythemia vera. Various considerations on this anatomo-functional structure].

Despite the initial description, more than 30 years ago, of an erythroblastic island (EI), little is known about the mechanisms of union and interaction between the different cells of this anatomical and functional bone marrow structure. The observation of entire Els is extremely uncommon in normal bone marrow aspirates because of their dispersion during spread. A case report is described in which a 73-year-old woman, diagnosed 20 years ago with polycythaemia vera, showed multiple Els in a bone marrow aspirate. Their immunophenotyping revealed deficiency of several integrins. The ultrastructural study indicated a marked erythroblastic rophalocytosis. A hypothesis is suggested in view of these observations.

Aged↗
PubMed1994

Isolation of a 32 kDa Mycobacterium tuberculosis protein by lectin affinity chromatography.

A 32 kDa antigen from delipidated M. tuberculosis H37Rv culture filtrate protein extract (CFPE) was purified by affinity chromatography on immobilized Lens culinaris lectin and electroelution. This antigen represents 0.4% of the total CFPE carbohydrate content and possesses galactose, xylose, mannose and GlcNAc (5:2:3:1 mol. ratio). A monoclonal antibody against the purified antigen reacted with the 32 kDa as well as a 30 kDa antigen in H37Rv CFPE, thus suggesting that both antigens represent closely related allelomorphic forms of the same antigen.

Antibodies, Bacterial↗