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Biomedical subjects

J Gomes

Publications and source records attributed to J Gomes.

At least 19 recordsLinked to original sources
PubMed2004

The interaction of oxygen with TiC(001): photoemission and first-principles studies.

High-resolution photoemission and first-principles density-functional slab calculations were used to study the interaction of oxygen with a TiC(001) surface. Atomic oxygen is present on the TiC(001) substrate after small doses of O(2) at room temperature. A big positive shift (1.5-1.8 eV) was detected for the C 1s core level. These photoemission studies suggest the existence of strong O<-->C interactions. A phenomenon corroborated by the results of first-principles calculations, which show a CTiTi hollow as the most stable site for the adsorption of O. Ti and C atoms are involved in the adsorption and dissociation of the O(2) molecule. In general, the bond between O and the TiC(001) surface contains a large degree of ionic character. The carbide-->O charge transfer is substantial even at high coverages (>0.5 ML) of oxygen. At 500 K and large doses of O(2), oxidation of the carbide surface occurs with the removal of C and formation of titanium oxides. There is an activation barrier for the exchange of Ti-C and Ti-O bonds which is overcome only by the formation of C-C or C-O bonds on the surface. The mechanism for the removal of a C atom as CO gas involves a minimum of two O adatoms, and three O adatoms are required for the formation of CO(2) gas. Due to the high stability of TiC, an O adatom alone cannot induce the generation of a C vacancy in a flat TiC(001) surface.

Journal Article↗
PubMed2003

[Priapism].

Priapism is a rare disease, characterized by a prolonged erection unrelated to sexual stimulus or desire. There are two distinct types of priapism with different etiologies, pathophysiology, treatment and complications. A better understanding of these two clinical entities brought about, in recent years, some progress in their treatment. The authors make a retrospective analysis of the 17 cases of priapism diagnosed in this centre in the last twelve years. From this experience they review the standard approach to this disease, both diagnostic and therapeutic.

Adult↗
PubMed2003

Highly thermostable amylase and pullulanase of the extreme thermophilic eubacterium Rhodothermus marinus: production and partial characterization.

Five strains of the extreme thermophilic Rhodothermus marinus were screened for the production of amylolytic and pullulytic activities. The culture medium for the selected strain, R. marinus ITI 990, was optimized using central composite designs for enhanced enzyme production. The optimized medium containing 1.5 gl(-1) of maltose and 8.3 gl(-1) of yeast extract yielded amylase, pullulanase and alpha-glucosidase activities of 45, 33 and 2.1 nkatml(-1), respectively. Among the various carbon sources tested, maltose was most effective for the formation of these enzymes, followed by soluble maize starch, glycogen and pullulan. The crude amylase and pullulanase showed maximum activities at pH 6.5-7.0, and 85 and 80 degrees C, respectively. At 85 degrees C amylase and pullulanase had half lives of 3 h and 30 min, respectively.

Amylases↗
PubMed2002

Decolorization of textile dyes by laccases from a newly isolated strain of Trametes modesta.

Four ligninolytic fungi, Trametes modesta, Trametes hirsuta, Trametes versicolor and Sclerotium rolfsii, were compared for their ability to produce laccases. The fungal laccases were screened for their ability to decolorize eight synthetic dyes (anthraquinone, azo, indigo and triarylmethane). The decolorization rate depended both on the source of the enzyme preparation and on the structure of the dye. Based on laccase production and dye decolorizing ability, T. modesta was selected for further studies. All the tested dyes were decolorized by the T. modesta laccase most efficiently under acid conditions (pH 3-6) but the optimum pH for decolorization of the individual dye varied. The decolorization rate of this laccase increased with the rise in temperature to 50-60 degrees C. The decolorization efficiency of T. modesta laccase was improved remarkably in the presence of mediators like 1-hydroxybenzotriazole and 2-methoxyphenothiazine.

Color↗
PubMed2002

Current role of simplified upper tract approach in the surgical treatment of ectopic ureteroceles: a single centre's experience.

OBJECTIVE: Despite renewed interest in either endoscopic decompression or complete reconstruction as primary approaches in ectopic ureterocele's (EU's) treatment, we advocate that a simplified upper tract approach is an optimal choice in a large subset of these patients. We review our surgical results to evaluate the effectiveness of different surgical procedures used in the treatment of EU, based on an individualized approach. PATIENTS AND METHODS: We retrospectively analysed all patients with EU and without previous treatment (n = 59) operated in this centre between the years 1991 and 2000. This disorder was bilateral in three patients (62 EU) and associated with duplex ureters in 60 cases. Vesicoureteral reflux (VUR) was diagnosed pre-operatively in 49.1% of patients. Treatment and choice of procedure was based on patients' age, clinical manifestations, associated abnormalities and function of the ureterocele-bearing moiety. Patients were divided in three separate groups according to the initial surgical approach. Group 1-11 patients submitted to endoscopic puncture (six urgent ureterocele decompression, four infants with obstruction of a functional ureterocele-bearing moiety and another with both lower pole ureter and mild bladder outflow obstruction). Group 2-30 patients (31 EU) submitted to a simplified upper tract approach--pyeloureterostomy (1), heminephrectomy (29) and nephrectomy (1) (all patients but one with non-viable renal segments; VUR, grade < or = III, present in six cases). Group 3-18 patients (20 EU) submitted to complete primary reconstruction (all patients with high-grade and/or contralateral reflux, with or without function of the ureterocele-bearing moiety). Success (clinically asymptomatic patients, without obstruction or VUR) and complication rates from the different approaches were analysed. For statistical evaluation, we used Fisher's exact test with p < or = 0.05 considered significant. RESULTS: The success rate of endoscopic treatment, simplified upper tract approach and complete reconstruction were 18.2%, 80% and 83.3%, respectively. Major complications occurred in two patients from group 3. CONCLUSION: Endoscopic puncture is our first option when immediate ureterocele decompression is required, although it seldom affords definitive treatment. Complete primary reconstruction is necessary in complex cases. Cure rates are high but there is a potential risk for serious complications. A simplified upper tract approach is curative in most patients without associated reflux. Heminephrectomy remains our first choice in a large subset of patients with non-viable or hypofunctional renal segments and without high-grade reflux.

Case-Control Studies↗
PubMed2002

Production of laccase by a newly isolated strain of Trametes modesta.

The effects of the carbon and nitrogen sources, initial pH and incubation temperature on laccase production by Trametes modesta were evaluated using the one-factor-at-a-time method. The final optimisation was done using a central composite design resulting in a four-fold increase of the laccase activity to 178 nkat ml(-1). Response-surface analysis showed that 7.34 g l(-1) wheat bran, 0.87 g l(-1) glucose, 2.9 g l(-1) yeast extract, 0.25 g l(-1) ammonium chloride, an initial pH of 6.95 and an incubation temperature of 30.26 degrees C were the optimal conditions for laccase production. Laccase produced by T. modesta was fully active at pH 4 and at 50 degrees C. The laccase was very stable at pH 4.5 and at 40 degrees C but half-lives decreased to 120 and 125 min at higher temperature (60 degrees C) and lower pH (pH 3).

Biotechnology↗
PubMed2002

The health of the workers in a rapidly developing country: effects of occupational exposure to noise and heat.

Occupational hygiene and safety have not been high on the agenda of industrial management in developing countries for a variety of reasons. This cross-sectional study was undertaken to assess the exposure to noise and heat, and to study the level of occupational hygiene practiced, at a foundry in a rapidly developing country (Dubai, United Arab Emirates). Audiometry, muscle cramps and visual acuity were measured in workers at a foundry and compared with the results from workers at a soft-drink bottling plant. Thermal stress, relative humidity, ventilation, illumination and noise levels were measured at different work units at the foundry and at the soft-drink bottling factory. Thermal stress index was high while relative humidity and ventilation were low at the foundry compared with the bottling plant. Noise levels were also high at the foundry, exceeding 90 dB at almost all work units except the fabrication workshop. Mild or moderate visual defects were observed among 31% of foundry workers, compared with 19% of the bottling plant workers.Muscle cramps were reported by 30% of all workers at the foundry, compared with 5% at the bottling plant. Visual disability was the highest among furnace operators and fabricators. Mean hearing disability was 8.69 +/- 1.08% among foundry workers, compared with 4.56 +/- 0.82% among bottling plant workers. The high thermal stress, noise levels and exposure to non-ionizing radiations at the foundry might have contributed to the higher frequency of muscle cramps and the greater hearing and visual disabilities, respectively, among these workers. Non-use of personal protective equipment and poor occupational hygiene and safety measures were also seen to affect eye and ear health adversely among the workers at the foundry.

Cross-Sectional Studies↗
PubMed2002

First account on the larval biology of a Litomosoides filaria, from a bat.

Litomosoides filariae are parasites of unrelated groups of hosts, including bats, marsupials, ancient and modern rodents. The four life cycles to-date elucidated, develop in terrestrial mammals and, at least experimentally, in the mite Ornithonyssus bacoti. A batch of mites was fed on an infected bat, Artibeus jamaicensis captured in Costa Rica, and 18 days later one infective larva was recovered. Its morphology was similar to that of other Litomosoides species, with the characteristic long buccal capsule. These first accounts on the larval biology of Litomosoides from Microchiroptera confirm the unity of the genus which supports the view that it has passed from one group of hosts to another by means of captures.

Acaridae↗
PubMed2001

Respiratory illnesses and ventilatory function among workers at a cement factory in a rapidly developing country.

Chronic exposure to Portland cement dust has been reported to lead to a greater prevalence of chronic respiratory symptoms and a reduction of ventilatory capacity. The seriousness of pulmonary function impairment and respiratory disease has not been consistently associated with the degree of exposure. Regular use of appropriate personal protective equipment, if available at the worksite, could protect cement workers from adverse respiratory health effects. For a variety of reasons, industrial workers in rapidly developing countries do not adequately protect themselves through personal protective equipment. This study explores the prevalence of chronic respiratory symptoms and ventilatory function among cement workers and the practice of use of personal protective equipment at work. An interviewer-administered questionnaire was used to collect information on sociodemographic characteristics, smoking profile and history of respiratory health among workers at a Portland cement plant (exposed) and workers occupationally unexposed to dust, fumes and gases (unexposed). Pulmonary function was assessed and pulmonary function impairment was calculated for the exposed and the unexposed workers. A higher percentage of the exposed workers reported recurrent and prolonged cough (30%), phlegm (25%), wheeze (8%), dyspnoea (21%), bronchitis (13%), sinusitis (27%), shortness of breath (8%) and bronchial asthma (6%). Among the unexposed, prevalences of these symptoms were 10, 5, 3, 5, 4, 11, 4 and 3%, respectively. Ventilatory function (VC, FVC, FEV(1), FEV(1)/VC, FEV(1)/FVC and PEF) was significantly lower in the exposed workers compared with unexposed workers. These differences could not be explained by age, body mass index (BMI) or pack-years smoked. Ventilatory function impairment, as measured by FEV(1)/FVC, showed that 36% of the exposed workers had some ventilatory function impairment compared with 10% of those unexposed. Certain jobs with greater exposure to cement dust had lower ventilatory function compared with others among the exposed workers. It was concluded that adverse respiratory health effects (increased frequency of respiratory symptoms and decreased ventilatory function) observed among cement workers could not be explained by age, BMI and smoking, and were probably caused by exposure to cement dust.

Adult↗
PubMed2001

Dust exposure and impairment of lung function at a small iron foundry in a rapidly developing country.

OBJECTIVES: A cross sectional prospective study was carried out among iron foundry workers (exposed) and soft drink bottling and supply company workers (unexposed) to assess their occupational exposure to ambient respiratory dust in their work environment and its effect on their lung function profile. PARTICIPANTS: Lung function was measured in 81 exposed and 113 unexposed workers. Personal respirable dust concentrations were measured for all the exposed and the unexposed workers. Information on respiratory signs and symptoms was also collected from the participants. RESULTS: Among the exposed workers, midexpiratory flow (FEF25-75), forced expiratory volume in 1 second (FEV1), peak expiratory flow (PEF), FEV1/FVC, and FEV1/VC ratios were significantly lower whereas the vital capacity (VC) and forced vital capacity (FVC) were non-significantly higher. Job at the iron foundry was a significant predictor of lung function. Exposure to high concentration of respirable dust at the iron foundry was also a significant predictor. Workers working in high exposure areas (general works, furnace, continuous casting areas, and fabrication workshop) had lower lung function values than workers in medium and low exposure areas. Smoking did not enhance the effects of exposure to dust on lung function. CONCLUSIONS: Exposure to respirable dust was higher among the iron foundry workers; and among these, general, furnace, rolling mill, and fabrication workers had higher exposures to dust than did workers in continuous casting, the mechanical workshop, and the bottling plant. Job type and exposure to dust were significant predictors of lung function. Implementation of industrial hygiene and proper and efficient use of personal protection equipment while at work could help to protect the respiratory health of industrial workers.

Case-Control Studies↗
PubMed2000

Optimisation of culture medium and conditions for alpha-l-Arabinofuranosidase production by the extreme thermophilic eubacterium Rhodothermus marinus.

The culture medium for Rhodothermus marinus was optimised on a shake-flask scale by using statistical factorial designs for enhanced production of a highly thermostable alpha-L-arabinofuranosidase (AFase). The medium containing 3.6 g/l birch wood xylan and 8.2 g/l yeast extract yielded a maximum of 110 nkat/ml AFase activity together with 125 nkat/ml xylanase and 65 nkat/ml beta-xylosidase activity. In addition, low levels of beta-mannanase (30 nkat/ml), alpha-galactosidase (0.2 nkat/ml), beta-galactosidase (0.3 nkat/ml), endoglucanase (5 nkat/ml) and beta-glucosidase (30 nkat/ml) were detected in the culture filtrate. Among the various carbon sources tested, birchwood xylan was most effective for the formation of AFase and xylanase activities, followed by oat spelt and beechwood xylans, and xylan-rich lignocelluoses (e.g., starch-free sugar beet pulp and wheat bran). Constitutive levels of enzyme activities were detected when the bacterium was grown on other polysaccharides and low-molecular-weight carbohydrates. A fermentation in a 5-l fermenter (3-l working volume) using the optimised medium yielded 60 nkat/ml AFase associated with 65 nkat/ml xylanase and 35 nkat/ml beta-xylosidase activities. The crude AFase displayed optimal activity between pH 5.5 and 7 and at 85 degrees C. It had half-lives of 8.3 h at 85 degrees C and 17 min at 90 degrees C. It showed high stability between pH 5 and 9 (24 h at 65 degrees C). The combined use of AFase-rich xylanase and mannanase from R. marinus in the prebleaching of softwood kraft pulp gave a brightness increase of 1.8% ISO. To our knowledge, this is the first report on the production of a high AFase activity by an extreme thermophilic bacterium and this enzyme is the most thermostable AFase reported so far.

Journal Article↗
PubMed2000

Simultaneous detection of different glycosidase activities by 19F NMR spectroscopy.

A fast method for the simultaneous detection of different glycosidolytic activities in commercially available enzyme preparations and crude culture filtrates was found in using, as substrate, a mixture of different glycosyl fluorides and 19F NMR spectroscopy as a screening technique. Accompanying studies regarding the hydrolytic stability of these fluorides in various buffer systems, as well as conditions of their long-term storage, were carried out. A simple procedure for the preparation of beta-D-mannopyranosyl fluoride in gram quantities is given.

Fluorine↗
PubMed2000

Simultaneous production of high activities of thermostable endoglucanase and beta-glucosidase by the wild thermophilic fungus Thermoascus aurantiacus.

The culture-medium composition was optimised, on a shake-flask scale, for simultaneous production of high activities of endoglucanase and beta-glucosidase by Thermoascus aurantiacus using statistical factorial designs. The optimised medium containing 40.2 g l(-1) Solka Floc as the carbon source and 9 g l(-1) soymeal as the organic nitrogen source yielded 1130 nkat ml(-1) endoglucanase and 116 nkat ml(-1) beta-glucosidase activities after 264 h as shake cultures. In addition, good levels of beta-xylanase (3479 nkat ml(-1)) and low levels of filter-paper cellulase, beta-xylosidase, alpha-L-arabinofuranosidase, beta-mannanase, beta-mannosidase, alpha-galactosidase and beta-galactosidase were detected. Batch fermentation in a 5-1 laboratory fermentor using the optimised medium allowed the production of 940 nkat ml(-1) endoglucanase and 102 nkat ml(-1) beta-glucosidase in 192 h. Endoglucanase and beta-glucosidase showed optimum activity at pH 4.5 and pH 5, respectively, and they displayed optimum activity at 75 degrees C. Endoglucanase and beta-glucosidase showed good stability at pH values 4-8 and 4-7, respectively, after a prolonged incubation (48 h at 50 degrees C). Endoglucanase had half-lives of 98 h at 70 degrees C and 4.1 h at 75 degrees C, while beta-glucosidase had half-lives of 23.5 h at 70 degrees C and 1.7 h at 75 degrees C. Alkali-treated bagasse, steam-treated wheat straw, Solka floc and Sigmacell 50 were 66, 48.5, 33.5 and 14.4% hydrolysed by a crude enzyme complex of T. aurantiacus in 50 h.

Ascomycota↗
PubMed2000

Thermolabile xylanase of the Antarctic yeast Cryptococcus adeliae: production and properties.

Xylanase production by the Antarctic psychrophilic yeast Cryptococcus adeliae was increased 4.3 fold by optimizing the culture medium composition using statistical designs. The optimized medium containing 24.2 g l(-1) xylan and 10.2 g l(-1) yeast extract and having an initial pH of 7.5 yielded xylanase activity at 400 nkat (nanokatal) ml(-1) after 168-h shake culture at 4 degrees C. In addition, very little endoglucanase, beta-mannanase, beta-xylosidase, beta-glucosidase, alpha-L-arabinofuranosidase, and no filter paper cellulase activities were detected. Among 12 carbon sources tested, maximum xylanase activity was induced by xylan, followed by lignocelluloses such as steamed wheat straw and alkali-treated bagasse. The level of enzyme activity produced on other carbon sources appeared to be constitutive. Among the complex organic nitrogen sources tested, the xylanase activity was most enhanced by yeast extract, followed by soymeal, Pharmamedia (cotton seed protein), and Alburex (potato protein). A batch culture at 10 degrees C in a 5-1 fermenter (3.5-1 working volume) using the optimized medium gave 385 nkat at 111 h of cultivation. The crude xylanase showed optimal activity at pH 5.0-5.5 and good stability at pH 4-9 (21 h at 4 degrees C). Although the enzyme was maximally active at 45 degrees - 50 degrees C, it appeared very thermolabile, showing a half-life of 78 min at 35 degrees C. At 40 degrees - 50 degrees C, it lost 71%-95% activity within 5 min. This is the first report on the production as well as on the properties of thermolabile xylanase produced by an Antarctic yeast.

Antarctic Regions↗
PubMed1999

Nutritional status and mortality of refugee and resident children in a non-camp setting during conflict: follow up study in Guinea-Bissau.

OBJECTIVE: To study the effects on children of humanitarian aid agencies restricting help to refugee families (internally displaced people). DESIGN: Follow up study of 3 months. SETTING: Prabis peninsular outside Bissau, the capital of Guinea-Bissau, which has functioned as a refugee area for internally displaced people in the ongoing war, and the study area of the Bandim health project in Bissau. PARTICIPANTS: 422 children aged 9-23 months in 30 clusters. MAIN OUTCOME MEASURES: Mid-upper arm circumference and survival in relation to residence status. RESULTS: During the refugee situation all children deteriorated nutritionally, and mortality was high (3.0% in a 6 week period). Rice consumption was higher in families resident in Prabis than in refugees from Bissau but there was no difference in food expenditure. Nutritional status, measured by mid- upper arm circumference, was not associated with rice consumption levels in the family, and the decline in circumference was significantly worse for resident than for refugee children; the mid-upper arm circumference of refugee children increased faster than that of resident children. For resident children, mortality was 4.5 times higher (95% confidence interval 1.1 to 30.0) than for refugee children. Mortality for both resident and refugee children was 7.2 times higher (1.3 to 133.9) during the refugee's stay in Prabis compared with the period after the departure of the refugees. CONCLUSION: In a non-camp setting, residents may be more malnourished and have higher mortality than refugees. Major improvements in nutritional status and a reduction in mortality occurred in resident and refugee children as soon as refugees returned home despite the fact that there was no improvement in food availability.

Eating↗
PubMed1999

The influence of personal protection, environmental hygiene and exposure to pesticides on the health of immigrant farm workers in a desert country.

OBJECTIVES: Farm workers in developing countries tend not to use protective measures while handling pesticides. This study investigates the use of personal protection equipment and the practice of safety and hygiene procedures in the handling of pesticides in agriculture. METHODS: Through a multi-stage sampling technique, one-fifth of the farms in a region were selected and all the farm workers at these farms were included in the study. A comparison population matching in age, socio-economic status and stay in the region was selected. A specifically designed questionnaire was used to collect information on the use of protective measures and the practice of safety and hygiene during work and on the disposal of empty pesticide containers. Blood pressure and erythrocyte acetylcholinesterase (AChE) activity were measured in the exposed and the unexposed populations. RESULTS: Protective equipment was worn by a minority of farm workers - gloves, by 35%; work coveralls, by 36%; a scarf to cover the nose and mouth, by 39%; and shoes at work, by 79%. With regard to personal hygiene measures, 83% of the workers changed clothes after work and the same proportion took a shower after work; 63% and 46% drank and ate while at work respectively; and 11% used articles of domestic use in the preparation of pesticides on the farm. Most of the farm workers (96%) were asked to prepare pesticides for spraying by the foreman and 61% were asked to spray the pesticides on the crops. AChE activity was highly significantly depleted in the exposed population as compared with the unexposed population. CONCLUSIONS: AChE depletion was found to be negatively associated with the use of gloves, of work coveralls, and of a scarf to cover the nose and mouth and with the implementation of safety and hygiene procedures on the farm. AChE depletion was positively associated with the frequency of pesticide spraying.

Acetylcholinesterase↗