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Biomedical subjects

A Roca

Publications and source records attributed to A Roca.

At least 19 recordsLinked to original sources
PubMed2006

Identification and physical mapping of induced translocation breakpoints involving chromosome 1R in rye.

To obtain translocations involving specific chromosomes in rye, pollen of a line in which chromosome 1R has large C-bands on its two telomeres, but which lacks C-bands (or has very small ones) on the telomeres of the remaining chromosomes, was X-irradiated. All translocations involving the labelled chromosome (1R) could be easily recognized in C-banded mitotic metaphases. The non-labelled chromosome involved in each translocation was identified either from mitotic C-banding analysis or from the meiotic configurations observed in some specific progenies. A physical map including 40 translocation breakpoints has been developed by means of synaptonemal complex (SC) analysis of well-paired pachytene quadrivalents. The results agree with the hypothesis of chromosomes 2R to 7R having similar probabilities of participating in translocations with chromosome 1R. However, the locations of the breakpoints are not entirely random: an excess of translocation breakpoints located on the short arm of chromosome 1R was obtained, and the two acentric translocated segments of each translocation show a trend towards having similar sizes. The possible reasons for these two non-random situations are discussed.

Chromosome Banding↗
PubMed2006

Bone mineral density in children with celiac disease. Effect of a Gluten-free diet.

OBJECTIVE: To assess the degree of osteopenia in children with celiac disease (CD) at the time of diagnosis and the effect of a gluten-free diet (GFD). DESIGN: Longitudinal and prospective study. SUBJECTS: In total, 24 children (18 girls, six boys) diagnosed with CD by means of an intestinal biopsy were included in the study. Mean+/-s.d. age was 4.9+/-4.3 years. In all, 16 patients were under (2.20+/-0.82 year) and eight were over the age of 4 years (10.30+/-2.90 year). The time between the first symptoms and diagnosis was 17.30+/-24.70 months (range: 2-109 months). Spine bone mineral content (BMC), area and bone mineral density (BMD) were measured by DXA at baseline and 1.17+/-0.93 years after GFD. RESULTS: Before treatment, mean+/-s.d. BMD was 0.46+/-0.13 g/cm(2), the BMD Z-score was -1.36+/-1.20, and was below -1 s.d. in 14 patients (58%). BMC, area and BMD increased significantly on GFD. BMD increased from 0.46+/-0.13 to 0.55+/-0.13 g/cm(2) (P<0.001). BMD Z-score improved from -1.36+/-1.20 to -0.23+/-1.20 after GFD. However, BMD increased more than 1 s.d. in 15 of the 16 children under the age of 4 years, a similar increase was only observed in four of the eight children aged more than 4 years, some of whom did not follow GFD strictly. Height and weight increased significantly with GFD (P<0.001) and the increase correlated positively with the increase in BMD. CONCLUSIONS: Axial BMD below -1 s.d. was found in 58% of children with celiac disease. Axial bone mass reverted to normal values in most children under the age of 4, who had low bone mass, all of whom followed GFD strictly.

Absorptiometry, Photon↗
PubMed2006

Community incidences of respiratory infections in an actively followed cohort of children <1 year of age in Manhiça, a rural area of southern Mozambique.

OBJECTIVE: To estimate the community incidence-rates of respiratory infections among infants in Manhiça, southern Mozambique, and to determine risk factors associated with these infections. METHODS: A cohort of children <1 year of age were visited at home every week until they turned one. During the visits, field workers recorded signs/symptoms of respiratory infections and tested the children for malaria parasites when they had fever. RESULTS: Between 1 July 1998 and 30 June 1999, 1,044 children contributed with 23,726 weeks at risk. Children met the criteria for acute respiratory infection in 19.2% of the visits, for lower respiratory infection in 0.9% and for severe lower respiratory infection in 0.2%. The crude incidence rate measured for acute respiratory infections was 23.0, that for lower respiratory infection was 0.9 and that for severe lower respiratory infection was 0.2 per 100-person-week-at-risk. The risk of acute and lower respiratory infection was inversely related to age. Females were at significantly lower risk for all three conditions than males. A trend of increased risk of severe lower respiratory infection was noted among children born during the rainy season (adjusted rate ratio = 1.95, P = 0.122 in only 47 episodes). Malaria was strongly associated with an increased risk of all three respiratory infections [rate ratio of 2.35, 10.90 and 13.82 (P < 0.001) in the adjusted analysis, respectively]. Thirty-five children died during the follow-up period; 20% of them from lower respiratory infection. Conclusions Respiratory infections are a major cause of morbidity and mortality among infants in rural Mozambique. Our study provides a better understanding of the associated determinants.

Acute Disease↗
PubMed2006

Invasive pneumococcal disease in children<5 years of age in rural Mozambique.

OBJECTIVES: To estimate the incidence and epidemiological characteristics of invasive pneumococcal disease (IPD) in children<5 years of age living in a rural area of southern Mozambique. METHODS: As part of the clinical management of children admitted to Manhiça District Hospital, prospective surveillance for invasive bacterial disease was conducted from June 2001 to May 2003. The level of antibiotic resistance of the isolates was also analysed. RESULTS: Pneumococcus was the most commonly isolated bacterium, accounting for 212 episodes. The estimated crude incidence rate of IPD in the study area among children<5 years of age was 416/100,000 per child-year at risk. The youngest age group (<3 months) had the highest incidence (779/100,000). Cases were detected during both rainy and dry seasons. The most common clinical diagnosis was pneumonia, made in 146/212 (69%) of the episodes of IPD. The overall case fatality rate was 10%, being highest among children with pneumococcal meningitis (5/9=56%). Pneumococcal isolates were highly susceptible to penicillin (86% susceptible and 14% with intermediate resistance) and chloramphenicol (98% susceptible). In contrast, up to 37% of the isolates tested were non-susceptible to cotrimoxazole. CONCLUSIONS: Incidence rates of IPD and associated mortality shown in this study highlight the need for pneumococcal vaccines in rural Africa, which must be effective in infants and young children.

Age Distribution↗
PubMed2004

Comparative analysis of transcriptional profiles between two apoptotic pathways of light-induced retinal degeneration.

Light exposure can exacerbate the condition of a variety of human retinal diseases by increasing the rate of photoreceptor cell death. How light negatively affects photoreceptor cell survival is not yet fully understood. Previous studies involving light damage models have revealed two independent apoptotic pathways: low levels of light induce retinal degeneration in the arrestin -/- mouse via constitutive activation of the phototransduction cascade, whereas strong light exposure to the retina, such as in an albino eye, elicits photoreceptor cell death via activator protein (AP-1) induction. In order to better understand the initial gene expression changes underlying light damage, dark-reared arrestin -/- and albino BALB/c mice were exposed to constant white light (2000 lux), and their retinal morphology was assessed as a function of time. The expression profiles of retinal transcripts were then compared between dark-adapted and light-exposed arrestin -/-, pigmented wild-type and BALB/c mice at a time point when morphological changes were minimal. As expected, the dark-adapted samples showed little difference in expression pattern between the three genotypes. Among the genes differentially regulated by light in BALB/c, but not arrestin -/- retinas, were c-fos and other stress-induced early response genes. In both mouse models, a marked increase in expression of the bZIP family of transcription factors was observed. Our results show a select group of unique and overlapping sets of genes induced by light in the two mouse models. These expression changes may constitute the underlying initiating events leading to the two distinct mechanisms of light damage.

Animals↗
PubMed2004

Recoverin regulates light-dependent phosphodiesterase activity in retinal rods.

The Ca2+-binding protein recoverin may regulate visual transduction in retinal rods and cones, but its functional role and mechanism of action remain controversial. We compared the photoresponses of rods from control mice and from mice in which the recoverin gene was knocked out. Our analysis indicates that Ca2+-recoverin prolongs the dark-adapted flash response and increases the rod's sensitivity to dim steady light. Knockout rods had faster Ca2+ dynamics, indicating that recoverin is a significant Ca2+ buffer in the outer segment, but incorporation of exogenous buffer did not restore wild-type behavior. We infer that Ca2+-recoverin potentiates light-triggered phosphodiesterase activity, probably by effectively prolonging the catalytic activity of photoexcited rhodopsin.

Adaptation, Physiological↗
PubMed2003

The effects of fish oil, olive oil, oleic acid and linoleic acid on colorectal neoplastic processes.

BACKGROUND AND AIMS: Several nutrients play a significant role in colorectal cancer development, and fats could be among the most determinant. While several studies have shown that the n-3 fatty acids eicosapentaenoic and docosahexaenoic and its main dietary source, fish oil could exert important antineoplastic effects, much less is known about the effects of olive oil and its main fatty acid, oleic acid, and linoleic acid. The aim of these studies is to assess the role of these nutrients in crucial processes involved in colorectal carcinogenesis. METHODS: Caco-2 and HT-29 colorectal cancer cells were supplemented with different fats and their role in apoptosis induction, cell proliferation, and differentiation was studied. COX-2 and Bcl-2 expressions were also assessed. RESULTS: Supplementation with fish oil or olive oil results in an induction of apoptosis and cell differentiation. The latest effect was also induced by oleic and linoleic acid. Fish oil diminishes significantly cell proliferation. Supplementation with fish oil and olive oil results in an early downregulation of COX-2 followed by a decrease in Bcl-2 expression. CONCLUSIONS: Fish oil and olive oil are capable of influencing crucial processes responsible for colorectal cancer development. COX-2 and Bcl-2 may be important mediators of some of these effects.

Apoptosis↗
PubMed2002

Inertization of pyrite cinders and co-inertization with electric arc furnace flue dusts by pyroconsolidation at solid state.

The viability of a pyroconsolidation process to render pyrite cinders inert and to co-inert pyrite cinders with a hazardous polymetallic residue such as electric arc furnace flue dusts (EAF) containing Pb, Cu, Zn, As, Cr, Ni and Mo were investigated. The effects of pyroconsolidation temperature (800-1200 degrees C), milling pyrite cinders and additions of both CaO and EAF on the resulting microstructure of the pellets were determined. The microstructural changes were then compared with the results of the standard leaching tests. Full inertization of pyrite cinders was achieved after milling to < 100 micron followed by a pelletization and pyroconsolidation process at a temperature of 1200 degrees C. This process also allows co-inertization of pyrite cinders with controlled additions of EAF (up to approximately to 10%). Following pyroconsolidation at 1200 degrees C, the metallic elements were inert components in the four main phases: traces of Cr in hematite; Cr, Cu, Zn and Ni in spinel-phase; traces of Cr and Zn in calcium ferrites; and Pb and traces of Cu, Zn and Ba in K-Ca-Al-Fe glassy silicate.

Electricity↗
PubMed2002

Mortality in severe sleep apnoea/hypopnoea syndrome patients: impact of treatment.

The aim of this study was to determine mortality in patients with sleep apnoea/hypopnoea syndrome (SAHS) according to the treatments employed and comorbidity. An historical cohort of patients with SAHS diagnosed at a university hospital between 1982 and 1992 and followed until 1996 was studied. From a total of 475 SAHS patients, 444 (94%), with a mean+/-SD apnoea/hypopnoea index at diagnosis of 55+/-27, were located and included in the study. SAHS treatments employed were: surgery (88), weight loss (134), continuous positive airway pressure (124) and 98 patients were not treated. By the end of follow-up, 49 patients had died. According to Cox regression analysis, mortality in treated patients was lower than in those not treated, but higher in those with a history of severe chronic obstructive pulmonary disease. Mortality in nontreated patients compared with that of the general population, adjusted for age and sex, showed excessive mortality, which decreased in treated patients. Stratification by age showed a greater mortality rate ratio in patients <50 yrs. These findings were maintained when mortality from cardiovascular causes was compared. In conclusion, a rise in mortality was found in nontreated sleep apnoea/hypopnoea syndrome patients compared with the general population, whereas mortality in those treated for sleep apnoea/hypopnoea syndrome did not differ significantly from that of the general population.

Comorbidity↗
PubMed2002

[Value of touch in the diagnosis of fever and of paleness in the diagnosis of anemia. Observational study in adults].

UNLABELLED: Estimation of fever by touch and of pallor as a sign of anemia are common practices during physical examination. The diagnostic value of these procedures has been extensively studied in children, but there are fewer studies in adults. OBJECTIVE: To evaluate the diagnostic value of physician's estimation of fever and anemia by touch and pallor, respectively. PATIENTS AND METHODS: The study included 600 patients (mean age 66 years, range 14-94 years, 58% males) admitted to a hospital (n = 300) or seen at its Emergency Department (n = 300). Two physicians independently estimated the presence of fever by touch, as well as the presence of anemia by pallor (in the skin, nail or conjunctiva). Axillary temperature and peripheral blood hemoglobin were employed as standards for comparison. RESULTS: Specificity of touch was higher than 90%, both for the diagnosis of axillary temperatures > or = 37.2 degrees C and > or = 38 degrees C, with a lower sensitivity. Interobserver concordance was fair (Kappa index, 0.47). Negative predictive value of touch was also high (99%) for the observed prevalence of fever (5%), with a very much lower positive predictive value. Similarly, specificity of pallor was high, particularly for hemoglobin values lower than 10 g/dL, with a substantially lower sensitivity. The best diagnostic values were obtained with conjunctival pallor. The Kappa index of concordance for the various types of pallor (skin, nail or conjunctiva) ranged between 0.39 and 0.44. Negative predictive value of pallor was high (98%) for the observed prevalence (9%) of significant anemia (hemoglobin < 10 g/dL), with a lower positive predictive value. CONCLUSIONS: In adult patients of a hospital, physi-cian's estimation of fever by touch and anemia by pallor have a relatively low diagnostic value. Nevertheless, the estimation that the patient is afebrile or not pale make very improbable the presence of fever and significant anemia, respectively.

Adolescent↗
PubMed2001

Intracellular distribution of glycogen synthase and glycogen in primary cultured rat hepatocytes.

Changes in the intracellular distribution of liver glycogen synthase (GS) might constitute a new regulatory mechanism for the activity of this enzyme at cellular level. Our previous studies indicated that incubation of isolated hepatocytes with glucose activated GS and resulted in its translocation from a homogeneous cytosolic distribution to the cell periphery. These studies also suggested a relationship with insoluble elements of the cytoskeleton, in particular actin. Here we show the translocation of GS in a different experimental model that allows the analysis of this phenomenon in long-term studies. We describe the reversibility of translocation of GS and its effect on glycogen distribution. Incubation of cultured rat hepatocytes with glucose activated GS and triggered its translocation to the hepatocyte periphery. The relative amount of the enzyme concentrated near the plasma membrane increased with time up to 8 h of incubation with glucose, when the glycogen stores reached their maximal value. The lithium-induced covalent activation of GS was not sufficient to cause its translocation to the cell periphery. The intracellular distribution of GS closely resembled that of glycogen. Our results showed an interaction between GS and an insoluble element of the hepatocyte matrix. Although no co-localization between actin filaments and GS was observed in any condition, disruption of actin cytoskeleton resulted in a significantly lower percentage of cells in which the enzyme translocated to the cell periphery in response to glucose. This observation suggests that the microfilament network has a role in the translocation of GS.

Animals↗
PubMed2001

Respiratory allergies on the staff of the police force.

The aim of the study was to evaluate respiratory allergies of an occupational nature in the staff of the police force. Five hundred and eighty-five subjects were submitted for lung function tests by dynamic spirometry. Subjects with a history of respiratory symptoms and border line respiratory function underwent bronchial provocation tests with methacholine. If FEV1 was < 80%, a bronchial reversibility test was performed. Allergic tests (skin and RAST) for inhalating allergens (perennial, seasonal and occupational) were performed. The results suggested asthmatic symptoms in 57 subjects, eight of whom were positive to skin and RAST tests for occupational inhalating allergens. Among these eight subjects, three had FEV1 < 80% of the theoretical value without therapy, and five showed obstruction of small caliber airways (MEF 25, MEF 50, FEF 25-75 < 65% of the theoretical value). The analysis showed a low percentage of respiratory occupational allergies. Among 21 subjects positive to Dermatophagoides, seven worked as archivists. In these workers, a concomitant occupational cause for the symptomatological and functional pattern was established.

Adult↗
PubMed2001

Urgent distal splenorenal shunt in low-body weight patients.

The authors report two patients with extrahepatic portal hypertension and repeated massive bleeding from esophageal varices who underwent urgent distal splenorenal shunting (DSRS) after having proved refractory to medical treatment, endoscopic sclerotherapy, and ligation of esophageal varices. Their ages and weights were 18 months/10 kg, and 11 months/6.4 kg, respectively. The splenic veins were 6 and 4 mm in diameter. During follow-up of 4 and 3 years, respectively, the shunts have remained patent in both patients as demonstrated by Doppler Ultrasound. Gastrointestinal hemorrhage has not recurred, splenomegaly regressed, and platelet and white blood cell counts increased gradually. Neither patient developed a significant encephalopathy, and liver function tests showed no significant changes throughout the observed period. The authors considered the shunting feasible despite the relatively narrow splenic veins. In both patients the anatomic position of the splenic vein--more caudal to the posterior wall of the pancreas--facilitated its isolation. In the smaller infant, the inferior mesenteric vein was sutured to gain a satisfactory segment of splenic vein. The successful use of a DSRS to control actively bleeding varices in a child weighing 6.4 kg has not been previously reported.

Angiography, Digital Subtraction↗
PubMed2001

Influence of setting on unattended respiratory monitoring in the sleep apnoea/hypopnoea syndrome.

The high demand for full polysomnography and the better quality of sleep at home are the main reasons for performing home sleep studies. Home respiratory monitoring has been evaluated in several studies, but the influence of setting on the results of unattended respiratory monitoring has not been assessed to date. Unattended monitoring of respiratory variables at home and in the sleep laboratory was conducted in 35 consecutive patients with suspected sleep apnoea/hypopnoea syndrome. Respiratory variables during sleep, rate of successful studies and patient preference were compared. The data acquisition failure rate was 2.8% in the sleep laboratory and 5.7% at home. The mean difference between apnoea/hypopnoea indices (AHI) obtained from home and laboratory studies was -0.21 +/- 8 (95% confidence interval 3.27-2.84). Using the method comparison approach of Bland and Altman, the limits of agreement of the mean difference between AHI home and AHI laboratory were -16.7 and 17.1. No difference was observed between the studies in time spent in different body positions. When patients were asked where they would prefer to repeat the sleep study, 53% replied at home, 28% in hospital and 19% showed no preference. It was concluded that the setting of unattended respiratory monitoring (home or sleep laboratory) influences neither the number of valid studies nor the results of the respiratory parameters measured; most patients, however, preferred home studies.

Adult↗
PubMed2000

Medicinal plants uses of the Tacana, an Amazonian Bolivian ethnic group.

We present the results of an ethnopharmacological investigation of a Bolivian lowland ethnic group, the Tacana. The Tacana have a long tradition of exchange with highland communities. Though facing rapid acculturation, highlighted by the loss of the Tacana language among the younger generations, the knowledge and uses of medicinal plants are still alive. Of the approximately 450 different plant species collected during this survey, 33% had medicinal uses. We present an overview of the traditional Tacana ethnomedicine and pharmacopoeia.

Bolivia↗