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Biomedical subjects

J Costa

Publications and source records attributed to J Costa.

At least 127 records · Page 7Linked to original sources
PubMed1997

Morphological and morphometric aspects of primate cornea: a comparative study with human cornea.

Morphological and morphometric features of the cornea of 13 species of primates have been studied in order to determine possible morphological differences between them. The existence of relationships between different morphometric corneal variables was also examined to establish which variables best defined and characterized the cornea. The present aim is to determine which primate cornea resembles that of the human being most with a view to possible future clinical and experimental studies. The results obtained revealed that all the cornea under study presented similar morphological features. The relationship between total corneal thickness and corneal epithelial thickness was determined as well as the relationship between epithelial thickness, the number of epithelial layers and the number of epithelial cells. However, the morphological pattern of Bowman's membrane and corneal endothelium differed in the species studied. Finally, the study indicates that the chimpanzee and the gorilla are the species with a corneal morphometry which is closest to that of the human cornea.

Animals↗
PubMed1997

Incidence and risk factors of hepatitis C virus infection in a haemodialysis unit.

BACKGROUND: Hepatitis viruses have become one of the main infectious problems in patients on maintenance haemodialysis. The aim of this study was to prospectively investigate the incidence of de novo hepatitis C virus (HCV) infection in a haemodialysis unit and to identify factors currently involved in HCV transmission to haemodialysis patients. METHODS: One hundred and fourteen anti-HCV negative and HCV-RNA negative patients who started long-term haemodialysis were followed for a mean period of 36 months (range 18-56). Liver tests and anti-HCV were performed at 6-month intervals. Factors that might be implicated in HCV transmission, such as blood transfusions, sexual habits, surgery and other invasive procedures, were recorded. HCV markers were re-examined in transfused blood and the HCV genotype was investigated in seroconverters to anti-HCV and in patients with previous HCV infection who were treated in the vicinity of those who seroconverted. RESULTS: Eight patients (7%) seroconverted to anti-HCV and seven of them became HCV-RNA positive. HCV markers, including HCV-RNA, were negative in the blood transfused to seroconverters. No differences between seroconverters and non-seroconverters. No differences found in other risk factors not directly related to haemodialysis. The investigation of HCV genotype suggested that HCV transmission was not restricted to patients treated in the vicinity of previously HCV infected patients. Occasional failure to observe strict measures of asepsis was detected in the haemodialysis unit and this was the only factor that might be incriminating. CONCLUSIONS: HCV acquisition in patients on haemodialysis is currently not related to blood transfusion, and nosocomial transmission within the haemodialysis unit seems to be the main mechanism of HCV infection. Extremely careful observation of preventive measures seems essential to eradicate HCV transmission in haemodialysis units.

Adult↗
PubMed1997

Hepatitis G virus infection in a haemodialysis unit: prevalence and clinical implications.

BACKGROUND: Hepatitis viruses have become one of the main infectious problems in patients on long-term haemodialysis. A new RNA virus, designated hepatitis G virus (HGV) has been recently identified. The pathogenic relevance of this virus is currently under investigation. The aim of this study was to analyse the prevalence and clinical implications of hepatitis G virus infection in patients on haemodialysis. METHODS: The presence of HGV-RNA was investigated in 96 patients on maintenance haemodialysis. Hepatitis viral markers (HBsAg, anti-HCV, HGV-RNA) and liver tests were assessed in all these patients, as well as the risk factors for hepatitis viruses acquisition. As a control group, 200 blood donors were tested for the presence of HGV-RNA. RESULTS: HGV-RNA was detected in 25 of 96 patients on haemodialysis (26%) and in six of 200 blood donors (3%) (P < 0.001). Thirteen of 25 HGV infected patients (52%) were coinfected with other hepatitis viruses (HBV and/or HCV). Evidences of chronic liver disease were more frequent in patients infected by HBV and/or HCV (61%) than in patients infected by HGV alone (17%) (P = 0.01). Although 80% of HGV infected patients had received blood products, the transfusion rate was not different from non HGV-infected patients. Time on haemodialysis was significantly shorter in patients infected with HGV alone (3.1 +/- 3.5 years) compared to patients infected with HBV and/or HCV (7.6 +/- 5.8 years) (P = 0.04). CONCLUSIONS: Patients on maintenance haemodialysis are at increased risk for HGV infection. HGV infection itself does not seem to be a frequent cause of chronic liver disease in these patients. Since the prevalence of HGV infection in blood donors is high, blood transfusion could be one of the main factors implicated in HGV transmission in patients on haemodialysis.

Adolescent↗
PubMed1997

Suspicion of quinolone active metabolite following discrepancy between predicted and experimental urine bactericidal activities.

The prediction of urine antibacterial activity from pharmacological and microbiological parameters was assessed by using experimental urine levels and urine bactericidal titers determined up to 72 h after a 400-mg single dose of two quinolones in a phase I study. The area under the bactericidal curve (AUBC) was accurately predicted for norfloxacin but significantly (P < 0.001) underestimated for rufloxacin (actual value was four times higher than the predicted value against Escherichia coli and two times higher against Staphylococcus aureus). In vitro susceptibility differences between the two strains predicted the ex vivo AUBC differences for norfloxacin but not for rufloxacin, where ex vivo differences were greater than expected. Urine bactericidal titers for up to 72 h were accurately predicted for norfloxacin against E. coli and S. aureus and for rufloxacin against S. aureus, but experimental activity for up to 48 h was four times higher (P < 0.001) than the predicted activity for rufloxacin against E. coli. In the case of norfloxacin, the duration of adequate urine antibacterial activity against S. aureus was overestimated. Inaccurate estimations of ex vivo antibacterial activity of a suspected active metabolite (as with rufloxacin) when an adequate cutoff is not established may have dosing implications.

Anti-Infective Agents↗
PubMed1997

Hepatitis G virus infection in fulminant hepatic failure.

BACKGROUND: RNA sequences of the recently identified hepatitis GB virus C (HGBV-C), also named hepatitis G virus (HGV), have been detected in patients with idiopathic fulminant hepatic failure (FHF) but the role of this agent in the disease remains controversial. AIMS: To investigate the presence and implications of HGV infection in a large series of Spanish patients with FHF. PATIENTS: Sixty eight patients with FHF, including 19 with idiopathic disease, were studied. In 28 cases, studies were performed before and after liver transplantation. For comparison 200 volunteer blood donors and 22 patients transplanted for chronic liver disease were also studied. METHODS: HGV RNA was measured in serum by reverse transcriptase polymerase chain reaction of the 5' non-coding region. RESULTS: Evidence of HGV infection was found in 3% (6/200) of blood donors and in 19% (13/68) of patients with FHF. HGV infection was more frequent in patients with hepatitis B (24%, 6/25) or hepatitis D (42%, 5/12), than in patients with idiopathic disease (11%, 2/19). Half of the patients with HGV infection used illicit intravenous drugs. Specific clinical features associated with HGV infection were not identified. A very high rate of infection with HGV was observed in patients who underwent liver transplantation, either for FHF (60%, 15/24) or chronic liver disease (45%, 9/20). CONCLUSIONS: In our geographical area, HGV infection is relatively frequent in FHF, but it does not seem to play a major role in idiopathic cases.

Adult↗
PubMed1997

Efficacy and safety of two new methods of rapid intravenous detoxification in heroin addicts previously treated without success.

BACKGROUND: New methods of rapid opiate detoxification, under intravenous sedation, can detoxify heroin-addicted patients in 24 hours. Their clinical application has been limited by the lack of studies establishing both efficacy and safety. METHOD: In a randomised, controlled study, 300 treatment-refractory, heroin-addicted patients received rapid intravenous detoxification treatment (naloxone infusion, 0.06-0.08 mg/kg, then oral naltrexone 50 mg/day) under either monitored light intravenous sedation or unmonitored deep intravenous sedation. RESULTS: All patients were successfully detoxified and 93% remained abstinent one month later. Severity of withdrawal, according to the Wang Scale modified by Loimer, was 4.9 (s.d. 3.0) points in the light sedation group and 4.8 (s.d. 2.9) in the deep sedation group (P = 0.26). Two patients (1.3%) in the light sedation group and four (2.6%) in the deep sedation group required tracheal intubation (P = 0.31). There was only one severe complication, a case of nosocomial aspirative pneumonia which improved with antibiotic treatment. CONCLUSIONS: Successful rapid intravenous detoxification can be achieved using relatively light levels of sedation.

Adult↗
PubMed1997

Comparative study of the National Cancer Institute and French Federation of Cancer Centers Sarcoma Group grading systems in a population of 410 adult patients with soft tissue sarcoma.

PURPOSE: Several histologic grading systems have been validated in soft tissue sarcomas (STS), but no system is currently accepted worldwide. The National Cancer Institute (NCI) and French Federation of Cancer Centers Sarcoma Group (FNCLCC) systems were examined comparatively in the same population of patients with STS to determine which system is the best prognosticator with regard to metastasis development and tumor mortality. PATIENTS AND METHODS: Four hundred ten adult patients with nonmetastatic STS were examined. Histologic grade was established according to the NCI and FNCLCC systems in each case. The prognostic value of both systems was examined using univariate and multivariate (Cox's model) analyses, and special attention was devoted to tumors with discordant grades. RESULTS: In univariate analysis, both the NCI and FNCLCC systems were of prognostic value to predict metastasis development and tumor mortality. In multivariate analysis, high-grade tumors, irrespective of the system used, size > or = 10 cm, and deep location were found to be independent prognostic factors for the advent of metastases. Tumor grade had a higher predictive value than size or depth, and higher prognostic weight was assigned to the FNCLCC grading system in Cox models. Grade discrepancies were observed in 34.6% of the cases. An increased number of grade 3 STS, a reduced number of grade 2 STS, and a better correlation with overall and metastasis-free survival within subpopulations with discordant grades were observed in favor of the FNCLCC system. CONCLUSION: The FNCLCC system showed slightly increased ability to predict distant metastasis development and tumor mortality. The use of this system to evaluate STS aggressiveness might be favored.

Adolescent↗
PubMed1997

Continuous automated telecare assessment of the elderly.

An automated scheme is proposed to assess the ability of elderly people to live alone in the community. It employs an Enhanced Activities of Daily Living index based on a computerized questionnaire form. In addition, a number of low-cost sensors have been developed which provide electronic measures of certain activities; these can provide additional inputs to the assessment form using telemetry. The sensors are capable of measuring a wide range of functional performance, thus providing the means of continuously and objectively assessing a patient's condition following hospitalization.

Activities of Daily Living↗
PubMed1997

Ki-ras mutation modifies the protective effect of dietary monounsaturated fat and calcium on sporadic colorectal cancer.

The geographic differences in the incidence of colorectal cancer have been mostly attributed to variations in diet. The diversity of the Mediterranean diet and the heterogeneity of acquired genetic alterations in colorectal cancer sets the stage for investigating the possible association between dietary factors and mutations in tumor genes known to play a role in the pathogenesis of these neoplasms. With this purpose, we have studied the Ki-ras gene in 108 colorectal cancers using archival tissue and epidemiological data from our previous case-control study. Mutations in exon 1 of the Ki-ras gene were detected by a PCR-single strand conformation polymorphism approach. A polychotomous logistic regression model was used to assess the significance of observed differences between wild-type and mutated tumors with respect to population controls in the different categories of nutrient consumption. Multivariate density models were used to adjust the correlation between nutrients and total energy. Our studies show that high consumption of monounsaturated fats, mostly derived from olive oil, is associated with a statistically significant decrease in the risk of cancer with wild-type Ki-ras genotype but not of Ki-ras mutated cancers. Conversely, we find that high calcium intake is associated with a decreased risk of Ki-ras mutated tumors but not of wild-type tumors. Tumor genotyping can reveal epidemiological associations that are weak or unapparent when cases-control studies are not stratified by tumor genotype.

Aged↗
PubMed1996

Detection of rare circulating human colon tumor cells in a nude mouse xenograft model.

A highly sensitive allele specific polymerase chain reaction was developed and applied to the detection of K-ras mutation in human colon tumor cells both in the blood and in tissues. An experimental model of human colon carcinoma cells, carrying a GAT mutation in the 12th codon of the K-ras gene, and grafted into nude mice has been selected for evaluating the occurrence of cells in the course of disseminating into the host. We have found tumor cells circulating in the blood starting 37 days following subcutaneous primary implantation. Occasional micrometastatic deposits could be detected in lymph node draining the xenograft, but no tumor cells were found in lungs and mediastinum. In this experimental model, our results indicate that the mere presence of tumor cells in the blood does not imply the full accomplishment of the multi-step metastatic process.

Animals↗
PubMed1996

Protease receptors in Hodgkin's disease: expression of the factor Xa receptor, effector cell protease receptor-1, in Reed-Sternberg cells.

The expression of a cellular receptor for the blood-clotting protease factor Xa, designated effector cell protease receptor-1 (EPR-1), was investigated in lymphoma. Immunohistochemical analysis demonstrated prominent reactivity of monoclonal antibodies to EPR-1 with Reed-Sternberg cells in 30 of 35 cases of nodular-sclerosis, lymphocyte-depletion, and mixed-cellularity Hodgkin's disease (HD). In contrast, several non-Hodgkin's lymphomas, or the nonneoplastic cellular components of HD, did not react with anti-EPR-1 monoclonal antibodies. A single molecular species of approximately 62 kD, consistent with the size and structural organization of EPR-1, was immunoblotted by an anti-EPR-1 monoclonal antibody from tissue samples of HD, but not from normal lymph nodes. Expression of EPR-1 transcripts in Reed-Sternberg cells was demonstrated by in situ hybridization with an antisense EPR-1 riboprobe, and by amplification of reverse-transcribed HD RNA with EPR-1-specific primers. These findings identify the factor Xa receptor, EPR-1, as a novel marker of Reed-Sternberg cells, and suggest its potential role in the histopathogenesis of HD.

Antibodies, Monoclonal↗
PubMed1996

[Role of hepatitis C virus in porphyria cutanea tarda hepatopathy].

BACKGROUND: Porphyria cutanea tarda has been classically considered as an acquired disorder due to the exerted influence of several factors (such as viral infections) on its fenotipic expression. The aim of the present study has been focussed on the prevalence analysis and the hepatotoxic role of the hepatitis C virus (HCV). PATIENTS AND METHODS: By means of a second generation ELISA test, serum antibodies against hepatitis C virus was studied in 132 patients with porphyria cutanea tarda. The polymerase chain reaction (PCR) was assayed in 55 cases to detect serum viral RNA. A liver biopsy was performed in 93 cases. RESULTS: The 64.4% of the studied patients were seropositive and PCR for HCV was positive in the 83% out of the 55 studied cases. The group of 19 patients suffering from familial porphyria cutanea tarda showed a similar prevalence to the group of 113 patients with sporadic porphyria (47.3% vs 67.2%). In 82% out of the total cases, risk factors for HCV infection were not found. In seropositive cases, both transaminases were more frequently altered than in seronegative ones. The univariant study was not able to demonstrate the relationship between seropositivity, and transaminases, urinary porphyrins alcohol consumption, frequency of antibodies against hepatitis B virus, relevance of the histological hepatic damage or incidence of porphyria relapses. Nevertheless, a multivariant analysis on 93 patients with liver biopsy showed that the risk to suffer from severe liver disease increases 2.8 times in seropositive patients, 3.13 times in those presenting high levels of serum ferritin and 9.25 times in patients up to 65 years old. CONCLUSIONS: The frequent hepatitis C virus infection in patients with porphyria cutanea tarda must be considered as a precipitating factor for the disease and as an aggravating factor of its associated liver damage.

Adult↗