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Biomedical subjects

A Mira

Publications and source records attributed to A Mira.

At least 19 recordsLinked to original sources
PubMed2001

Deletional bias and the evolution of bacterial genomes.

Although bacteria increase their DNA content through horizontal transfer and gene duplication, their genomes remain small and, in particular, lack nonfunctional sequences. This pattern is most readily explained by a pervasive bias towards higher numbers of deletions than insertions. When selection is not strong enough to maintain them, genes are lost in large deletions or inactivated and subsequently eroded. Gene inactivation and loss are particularly apparent in obligate parasites and symbionts, in which dramatic reductions in genome size can result not from selection to lose DNA, but from decreased selection to maintain gene functionality. Here we discuss the evidence showing that deletional bias is a major force that shapes bacterial genomes.

Bacteria↗
PubMed2001

Oxidative stress in Rett syndrome.

The investigation of parameters that might influence the neurological evolution of Rett syndrome might also yield new information about its pathogenic mechanisms. Oxidative stress caused by oxygen free radicals is involved in the neuropathology of several neurodegenerative disorders, as well as in stroke and seizures. To evaluate the free radical metabolism in Rett syndrome, we measured red blood cell antioxidant enzyme activities (superoxide dismutase, glutathione peroxidase, glutathione reductase and catalase) and plasma malondialdehyde, as lipid peroxidation marker in a group of patients with Rett syndrome. No significant differences were observed in erythrocyte glutathione peroxidase, glutathione reductase and catalase activities, between the Rett syndrome patients and the control group. Erythrocyte superoxide dismutase activities were significantly decreased in Rett syndrome patients (P<0.001) compared with the control group. Plasma malondialdehyde concentrations were significantly increased in Rett syndrome patients (P<0.001). An unbalanced nutritional status in Rett syndrome might explain the reduced enzyme activity found in these patients. Our results suggest that free radicals generated from oxidation reactions might contribute to the pathogenesis of Rett syndrome. The high levels of malondialdehyde reflect peroxidative damage of biomembranes that may contribute to progressive dementia, impaired motor function, behavioural changes, and seizures, in Rett syndrome. We found a probable relationship between the degree of oxidative stress and the severity of symptoms, which should be further investigated with a larger number of patients in different disease stages.

Adolescent↗
PubMed2000

Sex-specific differences in nitrogen intake and investment by feral and laboratory-cultured cockroaches.

We compared nutrient selection in a laboratory culture of the American cockroach (Periplaneta americana: Insecta, Blattodea) and a feral population which was founded by escapees from the culture approximately 14 generations prior to the study. In a first experiment, adult male and female cockroaches were provided with two nutritionally complementary synthetic foods, and thus allowed to select the protein and carbohydrate components of their diet independently. There were no differences in the amounts of carbohydrate eaten by the two populations. However, feral males ingested more protein than cultured males. In a second experiment, the construction of nitrogen budgets showed that the additional nitrogen ingested by feral males was allocated preferentially to accessory sex glands, rather than somatic tissue or excretion via the faeces. This suggests a possible role for sexual selection in the dietary difference between the strains. By contrast with males, there was no statistically significant difference in the amount of protein eaten by females of the two populations. However, feral females were found to have a higher density of bacterial endosymbionts than cultured females. Since these symbionts are involved in the synthesis of essential amino acids, this might account for greater reproductive output observed in a previous study in the feral compared with the culture females.

Journal Article↗
PubMed1999

Antioxidant status in anorexia nervosa.

OBJECTIVE: The study of the antioxidant status in female adolescents (N = 82) with anorexia nervosa, by the measurement of erythrocyte tocopherol concentration, and the determination of activities of the main antioxidant enzymes: superoxide dismutase, catalase, glutathione peroxidase, and glutathione reductase. METHOD: Tocopherol was measured by high-performance liquid chromatography (HPLC) with ultraviolet (UV) detection, and antioxidant enzyme activities by spectrometric methods using a Cobas Fara automated centrifugal analyzer. RESULTS: Tocopherol was significantly decreased in the anorexic patients compared to reference values (p < .02). In 21% of patients, tocopherol levels were below the reference interval. Superoxide dismutase activity was significantly decreased (p < .0001), while catalase activity was increased (p < .0001). The activity of the glutathione system enzymes did not show significant differences between patients and controls. DISCUSSION: The deficient concentration of erythrocyte tocopherol together with the altered antioxidant enzyme activities suggest a certain degree of oxidative damage in anorexia nervosa owing to both factors deficient micronutrient intake and oxidative stress.

Adolescent↗
PubMed1999

Comparative sensitivity of urinary CYFRA 21-1, urinary bladder cancer antigen, tissue polypeptide antigen, tissue polypeptide antigen and NMP22 to detect bladder cancer.

PURPOSE: We compare the individual and combined sensitivity of urinary CYFRA 21-1, urinary bladder cancer antigen, tissue polypeptide antigen and NMP22 to detect bladder cancer, evaluate the false-positive rates for different pathological conditions, and assess differential sensitivity regarding histological and clinical characteristics of disease. MATERIALS AND METHODS: A total of 267 subjects entered the study. Sensitivities of the tests were evaluated in 111 patients with active bladder cancer and 76 with no evidence of disease. False-positive rates were evaluated in 80 symptomatic and asymptomatic controls, including patients with benign urological conditions and nonbladder malignancies, and healthy subjects. CYFRA 21-1 was determined by electrochemoluminescent immunoassay in the Elecsys 2010, urinary bladder cancer antigen was quantified by enzyme linked immunosorbent assay (IDL Biotech), tissue polypeptide antigen was measured by the Prolifigen TPA-IRMA and NMP22 was assayed by enzyme linked immunosorbent assay (Matritech). Cutoffs were obtained by the 95% percentile in patients with no evidence of disease, which gave a 95% specificity for all biomarkers. Differences in sensitivity of urinary biomarkers regarding stage, grade, tumor size, pattern of growth, focality and recurrence were evaluated. RESULTS: At a specificity of 95% cutoffs were 5.4 ng./ml. for CYFRA 21-1, 15.5 microg./l. for urinary bladder cancer antigen, 760.8 U./l. for tissue polypeptide antigen and 14.6 U./ml. for NMP22. Using these cutoffs sensitivities were 75.7% for NMP22, 83.8% for CYFRA 21-1, 73.9% for urinary bladder cancer antigen quantitative and 80.2% for tissue polypeptide antigen. The additional determination of cytokeratins increased the sensitivity of NMP22. Cytokeratins did not appear to be specific for bladder cancer, and false-positives rates were between 20% for urinary bladder cancer antigen and 36% for tissue polypeptide antigen for benign urological conditions, and between 40% and 52%, respectively, for nonbladder malignancies. NMP22 showed lower false-positives rates, mainly for benign diseases. Urinary tumor markers appeared to be associated with some of the most relevant histological and clinical parameters of bladder cancer. CONCLUSIONS: Our preliminary evaluation showed the tests to be potential noninvasive adjuncts to help determine the need for cystoscopy. The combination of 2 tumor markers, NMP22 and 1 cytokeratin (CYFRA 21-1 or urinary bladder cancer antigen), seemed to be the most effective. Further comparative studies are needed to assess the promising diagnostic role of these markers.

Aged↗
PubMed1999

Initial evaluation of the new urinary bladder cancer rapid test in the detection of transitional cell carcinoma of the bladder.

OBJECTIVES: To evaluate the diagnostic performance of the new noninvasive urinary bladder cancer (UBC) rapid test in selected urine voided samples for the detection of transitional cell carcinoma (TCC) of the bladder, and to assess the differential sensitivity of the biomarker regarding the most relevant histologic and clinical parameters of bladder cancer. METHODS: Two hundred sixty-seven subjects were entered into the study and classified into five groups: 111 patients with active TCC of the bladder (group 1); 76 follow-up patients with TCC free from disease as confirmed by cystoscopy (group 2); 25 patients with other benign urologic diseases (group 3); 25 patients with other malignant pathologic conditions (group 4); and 30 healthy subjects (group 5). The UBC rapid test was measured by an immunochromatographic method that qualitatively detects the presence of fragments of cytokeratins 8 and 18 in the urine. UBC rapid test differences regarding stage, grade, tumor size, pattern of growth, focality, and recurrence were also evaluated. RESULTS: The sensitivity in group 1 was 78.4% and the specificity in group 2 was 97.4%. Positive and negative predictive values in groups 1 and 2 were 97.4% and 79.0%, respectively, with a global accuracy of 86.1%. False-positive rates were 20.0% and 44.0% for groups 3 and 4, respectively. The sensitivities of the UBC rapid test were associated with the histologic and clinical characteristics of bladder cancer, but not enough to reach statistical significance. CONCLUSIONS: The UBC rapid test appears to be a promising noninvasive adjunct that might guide the urologist in the decision to perform cytoscopy for the detection of TCC of the bladder. Further studies appear to be merited to assess its potential diagnostic role.

Aged↗
PubMed1999

Evaluation of nuclear matrix protein 22 as a tumour marker in the detection of transitional cell carcinoma of the bladder.

OBJECTIVES: To evaluate the sensitivity and specificity of urinary nuclear matrix protein-22 (NMP22) in detecting bladder cancer, to compare the diagnostic performance of NMP22 alone and when corrected by urinary creatinine level, and to correlate NMP22 level with the histological and clinical characteristics of bladder cancer. PATIENTS, SUBJECTS AND METHODS: The study included 267 patients classified into five groups: group 1 comprised 111 patients with active transitional cell carcinoma (TCC) of the bladder; group 2 included 76 patients who had had bladder TCC but were being followed and were free of disease, as confirmed by cystoscopy; group 3 comprised 25 patients with benign urological diseases; group 4 included 25 patients with other malignant pathological conditions; group 5 constituted a control group of 30 healthy subjects free of urological diseases. Urinary NMP22 was measured using an enzyme-linked immunosorbent assay. Receiver operating characteristic (ROC) curves were constructed to obtain the thresholds which gave optimal sensitivity and specificity for combinations of NMP22 alone and when corrected by urinary creatinine level. Stage, grade, tumour size, pattern of growth, focality and the presence of recurrence were recorded and their associations with NMP22 evaluated. RESULTS: The mean levels of NMP22 were 122.8, 5.1, 3.7, 2.3 and 0.3 U/mL for groups 1-5, respectively; overall, these values were significantly different (P<0.001). The mean (95% CI) optimal combination of 78.2% (69.3-85.5) sensitivity and 95.5% (87.3-99.0) specificity was obtained from the ROC analysis with a threshold value of 13.7 U/mL NMP22. When values were corrected by urinary creatinine levels, the threshold given by the best combination of sensitivity and specificity, at 73.2% (63.2-81.7) and 97.0% (89.6-99.5), respectively, was 3.0 U/mg creatinine. NMP22 level was statistically associated with stage, grade, tumour size and focality. CONCLUSIONS: Urinary NMP22 appeared to be a potential tumour marker for detecting TCC of the bladder; when corrected by urinary creatinine level, it might provide a better interpretation than when used alone. NMP22 correlated with the most relevant variables in bladder cancer. As a noninvasive adjunct, NMP22 might have a role in guiding urologists about the need for cystoscopy in such patients.

Biomarkers, Tumor↗
PubMed1999

Initial evaluation of the diagnostic performance of the new urinary bladder cancer antigen test as a tumor marker for transitional cell carcinoma of the bladder.

PURPOSE: We evaluated the diagnostic performance of the new noninvasive bladder cancer test on voided urine samples from patients with transitional cell carcinoma compared to symptomatic and asymptomatic controls. MATERIALS AND METHODS: Urinary bladder cancer antigen was measured in urine from 86 patients with active transitional cell carcinoma of the bladder (group 1), 76 patients free of transitional cell carcinoma as confirmed by cystoscopy at followup (group 2), 25 patients with other benign urological diseases (group 3), 25 patients with other malignant pathological conditions (group 4) and 30 healthy subjects free of urological diseases (group 5). RESULTS: Mean urinary bladder cancer antigen concentrations were 104.84, 4.57, 11.79, 48.87 and 1.38 microg/l, for groups 1 to 5, respectively, which was statistically different (p = 0.00005) except for groups 1 and 4 (p = 0.187). Sensitivity was 87.0% (95% confidence interval 79.2 to 92.7) and specificity was 86.8% (77.1 to 93.5%), and both were optimized by receiver operating characteristics plot analysis at a threshold value of 9.74 microg/l using asymptomatic (group 2) compared to known cancer (group 1) cases. CONCLUSIONS: Urinary bladder cancer antigen might have a role as a potential tumor marker for diagnosing transitional cell carcinoma of the bladder.

Aged↗
PubMed1999

New electrochemiluminescent immunoassay for the determination of CYFRA 21-1: analytical evaluation and clinical diagnostic performance in urine samples of patients with bladder cancer.

BACKGROUND: A new electrochemiluminescent immunoassay (ECLIA) has been developed for the determination of cytokeratin 19 (CYFRA 21-1) in the Elecsys 2010 immunoassay system. Urinary CYFRA 21-1 might have a role in the diagnosis of bladder cancer. METHODS: We performed an analytical evaluation of the CYFRA 21-1 ECLIA for serum and urine samples. The clinical value of urinary CYFRA 21-1 for the detection of bladder cancer was evaluated through its measurement in 226 urine samples from symptomatic and asymptomatic controls. RESULTS: At concentrations of 2-30 microg/L, within-assay imprecision (CV) was below 2.1% for sera and 3.3% for urines, with interassay CVs below 3.3% for sera and 4.9% for urines. The day-to-day CV was <20% at concentrations >0.2 microg/L (functional sensitivity). Measurement of diluted samples showed that the assay estimated CYFRA 21-1 between 98% and 103% for sera and 98% and 105% for urines. Recovery of added CYFRA 21-1 was 99-105% for sera and 96-115% for urines. We separately compared serum and urine CYFRA 21-1 ECLIA results with those obtained with an IRMA (CIS bio international). Regression analysis for sera was: CYFRA 21-1 (ECLIA) = 0.520 + 1.018 CYFRA 21-1 (IRMA); [95% confidence interval (CI) (y-intercept), -0.260 to 1.309]; 95% CI (slope), 0.978-1.060; n = 100; S(y|x) = 3.242; r(2) = 0.987. For urine samples it was: CYFRA 21-1 (ECLIA) = 0.716 + 0.966 CYFRA 21-1 (IRMA); 95% CI (y-intercept), 0.009-1.422; 95% CI (slope), 0.956-0.976; n = 100; S(y|x) = 4.136; r(2) = 0.986. In urine samples voided by patients with and without bladder cancer, the best ROC analysis discrimination provided 81.0% (95% CI, 72.7-87.7%) sensitivity and 97.2% (95% CI, 90.2-99.6%) specificity at a threshold value of 5.7 microg/L. CONCLUSIONS: Our initial evaluation showed reliable analytical performance for urinary CYFRA 21-1, which might assist urologists in the detection of bladder cancer as a noninvasive adjunct to cystoscopy.

Adult↗
PubMed1998

Why is meiosis arrested?

In mammals and birds, females are born with all the oocytes required for future ovulations. These oocytes are not haploid: they are arrested at the Prophase I of meiosis when they have two sister chromatids of each chromosome (i.e. the eggs are at the 4C stage). Under the assumption that the low number of ovulated eggs in these species have been selected to be of high quality, I propose three explanations for these two observations: (I) producing the eggs before birth may decrease the variance in mutations and genetic damage, thereby reducing risk; (II) arresting the oocytes at a 4C stage may allow sister-strand recombination to repair genetic damage; (III) arresting the oocytes at the 4C stage may mitigate intergametic conflict, hence potential selection of the oocytes for ovulation will not involve conflict. Predictions from the Mutational, Repair, and Conflict Hypotheses are critically evaluated in the light of unpublished data, evolutionary theory, and computer simulations.

Animals↗
PubMed1998

Antioxidant status in hyperphenylalaninemia.

Abnormal oxidative stress was observed in some inborn errors of metabolism owing to the accumulation of toxic metabolites leading to excessive free radical production and to the influence of restricted diets on the antioxidant status. Erythrocyte antioxidant enzymes activities and tocopherol concentrations were measured in a group of phenylketonuric (n = 42) and mild-hyperphenylalaninemic (n = 28) patients compared with 45 age-matched controls. We also determined plasma selenium levels in these groups. We also evaluated the possible relationship between antioxidant status and neuropsychological disorders. Erythrocyte glutathione peroxidase (GSH-Px) activity was significantly lower (P < 0.001) in both phenylketonuric and mild-hyperphenylalaninemic patients compared with the control group, but no differences were observed between the two groups of patients. Neuropsychological disturbances were more frequent in the group of PKU patients with low GSH-Px activity than in PKU patients with normal GSH-Px. Low GSH-Px activity might be explained in phenylketonuria as a result of a selenium deficiency caused by a poor selenium intake or absorption, but not in mild hyperphenylalaninemic patients with free diet. Selenium levels were normal in both groups of patients, so low glutathione peroxidase activity in both phenylketonuric and hyperphenylalaninemic groups might be influenced by other factors, such as the consequences of an unbalanced amino acid profile, common to both conditions.

Adolescent↗
PubMed1998

Antioxidant enzymes and fatty acid status in erythrocytes of Down's syndrome patients.

The excess of genetic information in patients with Down's syndrome (DS) produces an increase in the catalytic activity of superoxide dismutase (SOD1), an antioxidant enzyme coded on chromosome 21. It has been suggested that an increase in oxidative stress in DS patients may cause adverse effects in the cell membranes through the oxidation of polyunsaturated fatty acids (PUFAs). The aim of this study was to evaluate the cellular antioxidant system by determining the catalytic activity of the SOD1, glutathione peroxidase (GPx), catalase (CAT), and glutathione reductase (GR) enzymes and the concentrations of alpha-tocopherol in red blood cells (RBCs) in a group of 72 DS patients. The profile of fatty acids in the phospholipids of RBC membranes was also evaluated. The activity of the erythrocyte antioxidant enzymes is significantly higher in the DS group than in the control group (SOD1, 635 +/- 70 U/g Hb vs 476 +/- 67 U/g Hb; CAT, 1843 +/- 250 U/g Hb vs 1482 +/- 250 U/g Hb; GPx, 23.2 +/- 5.3 U/g Hb vs 21.5 +/- 3.6 U/g Hb; and GR, 9.32 +/- 1.4 U/g Hb vs 6.9 +/- 1.3 U/g Hb, respectively). No differences were observed in RBC alpha-tocopherol concentrations between the two groups studied. Long-chain n6 PUFA (C20:3n6, C20:4n6) concentrations were increased in DS patients, suggesting enhanced delta-6-desaturase activity. The long-chain n3 PUFA (docosahexenoic acid) does not appear to be affected by increased oxidative stress, probably because of the existence of compensatory antioxidant mechanisms.

Adolescent↗
PubMed1997

[Diagnosis of tuberculosis in children. Evaluation of the PCR technique].

OBJECTIVE: The purpose of this study was to evaluate the usefulness of the technique of polymerase chain reaction (PCR) for the diagnosis of tuberculosis in the pediatric population. PATIENTS AND METHODS: All patients seen at the University Hospital Sant Joan de Déu in Barcelona during the year of 1995 in which there was a clinical suspicion of or an interest in discarding tuberculosis were studied. Two types of diagnoses were considered: 1) Diagnosis from clinical evidence without microbiological confirmation, 2) A certain diagnosis including microbiological confirmation. All samples received at the microbiology laboratory were processed by baciloscopy, culture and PCR, Amplicor PCR M. tuberculosis was used as the PCR method. RESULTS: Sixty-four samples (most of them gastric juices) from 41 children were processed during the study period. Fourteen patients, between 8 months and 17 years of age, were diagnosed of tuberculosis, Microbiological confirmation by culture and/or PCR was obtained in four patients (31%). PCR was the only positive technique in one child (staining and culture negative) with clinical evidence of tuberculosis. All samples from the other three patients that had positive cultures also had positive PCR results. False positives were not detected. CONCLUSIONS: PCR improves the diagnosis of pediatric tuberculosis. It stands out because of its quickness (possibility of a 9 hour turn-around time), sensitivity (slightly higher than cultures in our series) and specificity.

Adolescent↗
PubMed1996

Distributed intelligent data analysis in diabetic patient management.

This paper outlines the methodologies that can be used to perform an intelligent analysis of diabetic patients' data, realized in a distributed management context. We present a decision-support system architecture based on two modules, a Patient Unit and a Medical Unit, connected by telecommunication services. We stress the necessity to resort to temporal abstraction techniques, combined with time series analysis, in order to provide useful advice to patients; finally, we outline how data analysis and interpretation can be cooperatively performed by the two modules.

Computer Communication Networks↗
PubMed1987

[Simultaneous determination of total and immature neutrophil C-reactive protein in normal, diseased, and infected newborn infants].

C. reactive protein and immature neutrophils/total neutrophils ratio are measured in 146 newborns. Three groups are considered: 37 healthy, 90 pathologic non infected and 19 bacteriologically confirmed infected newborns. Pathologies other than infection do not alter CRP nor I/T. Levels lower than 20 mg/l for CRP and 0.18 for I/T are considered normal. Both tests are considered very useful for neonatal infection diagnosis (p less than 0.001). CRP shows a higher sensitivity than I/T in neonatal infection diagnosis even in its initial period (84% versus 63%).

Bacterial Infections↗
PubMedDate not supplied

Some adaptive monte carlo methods for Bayesian inference.

Monte Carlo methods, in particular Markov chain Monte Carlo methods, have become increasingly important as a tool for practical Bayesian inference in recent years. A wide range of algorithms is available, and choosing an algorithm that will work well on a specific problem is challenging. It is therefore important to explore the possibility of developing adaptive strategies that choose and adjust the algorithm to a particular context based on information obtained during sampling as well as information provided with the problem. This paper outlines some of the issues in developing adaptive methods and presents some preliminary results.

Algorithms↗