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Biomedical subjects

A Castro

Publications and source records attributed to A Castro.

At least 91 records · Page 5Linked to original sources
PubMed2003

[Severe course and contingent risk factors in optic neuropathy and myelopathy after tuberculostatics].

A male patient with tuberculous lymphadenopathy was treated with a four-fold therapy of ethambutol, isoniacide, rifampicin and pyracinamide. After 10 weeks the patient suffered from photophobia. Although ethambutol was discontinued vision decreased and visual field defects occurred as well as signs of myelopathy. Isoniacide was then discontinued and in the subsequent phase the vision was slowly restored over a period of 36 months. The combined toxicity of ethambutol and isoniacide seems to have been the main cause of the severe and protracted optic neuropathy.

Adult↗
PubMed2003

Early elimination of cyclosporine in kidney transplant recipients receiving sirolimus prevents progression of chronic pathologic allograft lesions.

Cyclosporine elimination in a regimen including sirolimus has been shown to be a safe and effective approach to improve graft function. Nevertheless, it is still unknown whether the functional benefit of CyA withdrawal coincides with a subsequent reduction in histologic lesions of chronic damage or development of chronic allograft nephropathy. This consideration would forecast a reduction in the rate of long-term graft loss. We analyzed 114 graft biopsies from a subgroup of 57 patients that had been included in a randomized study to eliminate CyA at 3 months posttransplant from a regimen including sirolimus either in group A CyA + SRL vs group B of SRL with CyA elimination at 3 months. Every patient had two biopsies, one at transplantation and another at 1 year. The biopsy reading was performed in a blinded manner by a central pathologist using the Banff 1997 and the CADI classifications. A significantly lower rate of progression of tubular and interstitial chronic lesions between basal and 1-year biopsies was observed for group B patients. In addition, the incidence of new cases of chronic allograft nephropathy during the first year was significantly lower in the group in which CyA had been eliminated at 3 months posttransplant. We conclude that early elimination of CyA in the first months posttransplant, when SRL is used as the main immunosuppressant, reduces the appearance or worsening of chronic histologic lesions, probably as a consequence of long-term CyA toxicity prevention.

Biopsy↗
PubMed2003

Variation in the extent of microsatellite instability in human cell lines with defects in different mismatch repair genes.

Mismatch repair deficiency results in the elevation of mutation rates in tumors, which is especially pronounced in simple repeat sequences (microsatellites). We have investigated the relationship between microsatellite mutagenesis and certain combinations of mutations in mismatch repair genes, using a frameshift reversion assay to determine the spontaneous mutation rates of a dinucleotide microsatellite in two cancer cell lines, HCT116, which has defects in hMLH1 and hMSH3, and HEC-1-A, which has defects in hPMS2 and hMSH6. We found a 10-fold difference in mutation rates between these two cell lines. In addition, a mutant hPMS2 allele, PMS134, which has been reported to have a dominant negative effect, was expressed in mismatch repair-proficient telomerase-immortalized hTERT-1604 fibroblasts and mutation rates were determined. Expression of PMS134 did not elevate mutation rates in hTERT-1604. Combined, these results suggest that mutations in different mismatch repair genes can lead to varying degrees of microsatellite instability. It is also likely that there is heterogeneity in the mutations that are acquired in the absence of mismatch repair, such that some mismatch repair-defective cancer cells also contain mutations in other genes coding for proteins involved in the maintenance of genetic stability.

Base Pair Mismatch↗
PubMed2003

[GB virus C: lack of association with transaminases levels, CD4 and HIV viral load in aids patients].

OBJECTIVE: To study the prevalence of GBV-C-RNA in sera of HIV-infected patients and determine whether differences in immunological condition and hepatic disease exist between GBV-C positive and negative patients. METHODS: The presence of GBV-C-RNA was determined in sera of 222 HIV-positive patients by semi-automated RT-PCR. A comparison of GBV-C-RNA positive and negative patients was made by studying a series of clinical and analytical parameters. This same comparison was made in particular between those coinfected with HCV and GBV-C and those who only presented GBV-C. RESULTS: Prevalence of GBV-C-RNA was 28.8%. The most frequent hepatotropic virus was HCV, appearing in 71.6% of cases. Coinfection with HCV and HGV was present in 17% and 8.6% only had GBV-C. Patients positive for GBV-C-RNA showed clinical and analytical characteristics similar to those found in GBV-C-RNA negative patients. Among the HCV-GBV-C coinfected and those presenting HGV as the only virus it was observed that the coinfected group presented alterations in transaminases and predominance of parenteral transmission as a risk factor for HIV, whereas the GBV-C group presented normal transaminases and predominance of sexual transmission. No differences were perceived in mean CD4 and HIV-RNA values in both groups. CONCLUSIONS: Being positive for GBV-C in HIV-positive patients does not influence the presence of hepatic disease that in these patients is frequently accompanied by coinfection with other hepatotropic viruses. Moreover, it does not seem to influence the viremia of the HIV nor the CD4 cell counts.

Adolescent↗
PubMed2003

Validated HPLC method for the determination of ranitidine in plasma.

A validated HPLC method for the determination of ranitidine in human plasma is presented. Sulfanilamide as internal standard (IS) was used. Plasma samples were purified by solid phase extraction (SPE) using a copolymeric [poly(divinyl-benzene-co-N-vinylpyrrolidone)] column ("Oasis Waters"). Mobile phase consisting of dibasic potasium phosphate 0.08 M/acetonitrile/methanol/triethylamine 0.05% (89.5:3:7:0.05) pH5 was used at a flow rate of 0.9 ml/min on a C18 column (Nova-Pack, 3,9 x 300 mm, Waters). The eluate was monitored using an UVNis detector set at 300 nm. Ratio of peak area of ranitidine to sulfanilamide was used for the quantitation of plasma samples. FDA criteria for bioanalytical validation was used to validate the method. Linearity was assessed between 100-1600 ng/ml, the limit of quantitation was 100 ng/ml and recovery was greater than 94%. Accuracy, precision and selectivity met the current recommendations for bioanalytical method validation. The method was successfully used in a bioavailability study of a ranitidine tablet in healthy volunteers.

Anti-Ulcer Agents↗
PubMed2002

Limits on extra dimensions and new particle production in the exclusive photon and missing energy signature in pp collisions at square root [s]=1.8 TeV.

The exclusive gammaE(T) signal has a small standard model cross section and is thus a channel sensitive to new physics. This signature is predicted by models with a superlight gravitino or with large extra spatial dimensions. We search for such signals at the Collider Detector at Fermilab, using 87 pb(-1) of data at square root [s]=1.8 TeV, and extract 95% C.L. limits on these processes. A limit of 221 GeV is set on the scale |F|(1/2) in supersymmetric models. For 4, 6, and 8 extra dimensions, model-dependent limits on the fundamental mass scale M(D) of 0.55, 0.58, and 0.60 TeV, respectively, are found. We also specify a "pseudo-model-independent" method of comparing the results to theoretical predictions.

Journal Article↗
PubMed2002

Search for new physics in photon-lepton events in pp collisions at sqrt[s] = 1.8 TeV.

We present the results of a search in pp collisions at sqrt[s] = 1.8 TeV for anomalous production of events containing a photon and a lepton (e or mu), both with large transverse energy, using 86 pb(-1) of data collected with the Collider Detector at Fermilab during the 1994-1995 collider run at the Fermilab Tevatron. The presence of large missing transverse energy (E(T)), additional photons, or additional leptons in these events is also analyzed. The results are consistent with standard model expectations, with the possible exception of photon-lepton events with large E(T), for which the observed total is 16 events and the expected mean total is 7.6+/-0.7 events.

Journal Article↗
PubMed2002

Upsilon production and polarization in p p macro collisions at square root of s = 1.8 TeV.

We report on measurements of the Upsilon(1S), Upsilon(2S), and Upsilon(3S) differential cross sections (d(2)sigma/dp(T)dy)(/y/<0.4), as well as on the Upsilon(1S) polarization in p p macro collisions at square root of s = 1.8 TeV using a sample of 77+/-3 pb(-1) collected by the collider detector at Fermilab. The three resonances were reconstructed through the decay Upsilon-->mu(+)mu(-). The measured angular distribution of the muons in the Upsilon(1S) rest frame is consistent with unpolarized meson production.

Journal Article↗
PubMed2002

Diffractive dijet production at sqrt[s] = 630 and 1800 GeV at the Fermilab Tevatron.

We report a measurement of the diffractive structure function F(D)(jj) of the antiproton obtained from a study of dijet events produced in association with a leading antiproton in pp collisions at sqrt[s] = 630 GeV at the Fermilab Tevatron. The ratio of F(D)(jj) at sqrt[s] = 630 GeV to F(D)(jj) obtained from a similar measurement at sqrt[s] = 1800 GeV is compared with expectations from QCD factorization and other theoretical predictions. We also report a measurement of the xi ( x-Pomeron) and beta ( x of parton in Pomeron) dependence of F(D)(jj) at sqrt[s] = 1800 GeV. In the region 0.035<xi<0.095, /t/<1 GeV2, and beta<0.5, F(D)(jj)(beta,xi) is found to be of the form beta(-1.0+/-0.1)xi(-0.9+/-0.1), which obeys beta-xi factorization.

Journal Article↗
PubMed2002

Search for new heavy particles in the WZ0 final state in pp collisions at square root[s] = 1.8 TeV.

We present the first general search for new heavy particles, X, which decay via X --> WZ0 --> e(nu)+jj as a function of M(X) and Gamma(X) in pp collisions at square root[s] = 1.8 TeV. No evidence is found for production of X in 110 pb(-1) of data collected by the Collider Detector at Fermilab. General cross section limits are set at the 95% C.L. as a function of mass and width of the new particle. The results are further interpreted as mass limits on the production of new heavy charged vector bosons which decay via W' --> WZ0 in an extended gauge model as a function of the width, Gamma(W'), and mixing factor between the W' and the standard model W bosons.

Journal Article↗
PubMed2002

Study of B0 --> J/psiK(*)0pi(+)pi(-) decays with the collider detector at Fermilab.

We report a study of the decays B0 --> J/psiK(*)0pi(+)pi(-), which involve the creation of a uu or dd quark pair in addition to a b -->c(cs) decay. The data sample consists of 110 pb(-1) of pp collisions at square root[s] = 1.8 TeV collected by the CDF detector at the Fermilab Tevatron collider during 1992-1995. We measure the branching fractions to be B(B0 --> J/psiK(*0)pi(+)pi(-)) = (6.6 +/- 1.9 +/- 1.1)x10(-4) and B(B0 --> J/psiK0pi(+)pi(-)) = (10.3 +/- 3.3 +/- 1.5)x10(-4). Evidence is seen for contributions from psi(2S)K(*)0, J/psiK0rho(0), J/psiK(*+)pi(-), and J/psiK1(1270).

Journal Article↗
PubMed2002

Measurement of the strong coupling constant from inclusive jet production at the Tevatron pp collider.

We report a measurement of the strong coupling constant, alpha(s)(MZ), extracted from inclusive jet production in pp collisions at square root[s] = 1800 GeV. The QCD prediction for the evolution of alpha(s) with jet transverse energy ET is tested over the range 40<ET<450 GeV using ET for the renormalization scale. The data show good agreement with QCD in the region below 250 GeV. The value of alpha(s) at the mass of the Z0 boson averaged over the range 40<ET<250 GeV is found to be alpha(s)(MZ) = 0.1178+/-0.0001(stat)+0.0081(-0.0095)(expt. syst). The associated theoretical uncertainties are mainly due to the choice of renormalization scale ((+6%)(-4%)) and input parton distribution functions (5%).

Journal Article↗
PubMed2002

Search for gluinos and scalar quarks in pp collisions at square root[s] = 1.8 TeV using the missing energy plus multijets signature.

We have performed a search for gluinos (g) and scalar quarks (q) in a data sample of 84 pb(-1) of pp collisions at square root[s] = 1.8 TeV, recorded by the Collider Detector at Fermilab. We investigate the final state of large missing transverse energy and three or more jets, a characteristic signature in R-parity-conserving supersymmetric models. The analysis has been performed "blind," in that the inspection of the signal region is made only after the predictions from standard model backgrounds have been calculated. Comparing the data with predictions of constrained supersymmetric models, we exclude gluino masses below 195 GeV/c2 (95% C.L.), independent of the squark mass. For the case m(q) approximately m(g), gluino masses below 300 GeV/c2 are excluded.

Journal Article↗
PubMed2002

Detection of HCV RNA in saliva of patients with hepatitis C virus infection by using a highly sensitive test.

Hepatitis C virus (HCV) is transmitted primarily by direct percutaneous exposures to blood. Since HCV RNA has been found in saliva, it has been suggested that saliva might also be a source of infection. HCV RNA in saliva from plasma HCV RNA positive patients was tested by a highly sensitive PCR method. HCV RNA was detected in 32 out of 61 saliva specimens (52.4%). No correlation was found between the presence of HCV in saliva and age, sex, identified risk factors for HCV infection, time lapsed since the diagnosis, transaminases and alkaline phosphatase values and stimulated salivary flow. A statistically significant relation between plasma HCV RNA viral load and saliva HCV RNA detection was observed (P<0.001). In conclusion, HCV RNA is often present in saliva of HCV infected patients, with plasma viral load being the only known predictable factor. Further studies on salivary HCV RNA are needed.

Adult↗
PubMed2002

Synthesis of new 3-methylthio-5-aryl-4-isothiazolecarbonitriles with broad antiviral spectrum.

The isothiazole derivative 3-methylthio-5-(4-OBn-phenyl)-4-isothiazolecarbonitrile, coded IS-50, which in previous studies had exhibited a broad antipicornavirus spectrum of action, was selected as the model for the synthesis of a new series of 3-methylthio-5-aryl-4-isothiazolecarbonitriles. These compounds were prepared in good yield (from 66 to 82%) by alkylation of 3-methylthio-5-(4-hydroxyphenyl)-4-isothiazolecarbonitrile with suitable bromides in the presence of acetone; only the 4-cyanophenoxy derivatives were obtained in a yield of less than 30%. All the compounds were screened against a panel of 17 representative human rhinovirus (HRV) serotypes belonging to both A and B groups, enteroviruses polio 1, ECHO 9 and Coxsackie B1, cardiovirus EMC, measles virus, and herpes simplex virus type 1 (HSV-1). Our results demonstrate that HRV 86 (group A) and HRVs 39 and 89 (group B) are the rhinovirus serotypes more susceptible to the action of these compounds. Isothiazole derivatives with a longer intermediate alkyl chain exhibited good activity against polio 1 and ECHO 9. The compound bearing a butyl group between the two phenoxy rings showed the lowest IC(50) against Coxsackie B1 and measles viruses. No activity against HSV-1 was detected with any of the compounds screened.

Antiviral Agents↗
PubMed2002

Interferon-alpha plus ribavirin for 12 months increases the sustained response rates in chronic hepatitis C relapsers.

BACKGROUND: The effectiveness and tolerability of combination therapy for 12 months have not been evaluated sufficiently in chronic hepatitis C relapsers to interferon. AIMS: To evaluate the sustained response to interferon plus ribavirin for 12 months in chronic hepatitis C relapsers. METHODS: We included 55 chronic hepatitis C relapsers in a 12-month treatment protocol with interferon (3 MU thrice weekly) plus ribavirin (1-1.2 g/day). The effectiveness was evaluated using serum aminotransferase and hepatitis C virus RNA levels, alanine aminotransferase normalization and viraemia clearance after 12 months, defining the end-of-treatment response, and 6 months after completion of therapy, defining the sustained response. Adverse effects were recorded. RESULTS: End-of-treatment response and sustained response were achieved in 47 (85%) and 37 (67%) patients, respectively; there were 10 (21%) relapsers after combination therapy. Predictive factors of sustained response included the genotype (non-1 95% vs. 1 48%; P < 0.001), lower viraemia (503 917 +/- 553 230 vs. 901 393 +/- 548 267 copies/mL; P < 0.005), higher alanine aminotransferase levels (137 +/- 75 vs. 103 +/- 41 IU/L; P < 0.05) and a lower gamma-glutamyl transpeptidase/alanine aminotransferase ratio (0.30 +/- 0.23 vs. 0.49 +/- 0.39; P < 0.05). Tolerance to therapy was good, with no withdrawals. CONCLUSIONS: Interferon plus ribavirin treatment for 12 months in chronic hepatitis C relapsers yields high sustained response rates and is well tolerated. The sustained response is related to a non-1 genotype, lower baseline viraemia, higher alanine aminotransferase level and a lower gamma-glutamyl transpeptidase/alanine aminotransferase ratio.

Adult↗
PubMed2002

Construction of a system for the access, storage and exploitation of data and medical images generated in radiology information systems (RIS).

We present the analysis, design and implementation of a system that allows specialists at a medical centre to recuperate and manage information produced by computers that generate medical diagnosis images. The main objective of the system is to define an architecture that provides doctors with an easy and centralized access to any information they may need, and to allow users to access this information from the computers at the hospital itself as well as from remote locations, which then require telemedicine sessions. The architecture is built according to a layered and modular methodology, which provides high scalability and interoperability with other information systems (HIS, RIS, etc). All the information is stored in a database: not only the various image studies of the patient, but also all data concerning the diagnosis and any comments the specialist may have made. We have also incorporated tools that are not usually found in conventional systems (image segmentation, advanced visualization, etc), but that help the specialist with the decision-making process.

Diagnostic Imaging↗