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Biomedical subjects

J Gomes

Publications and source records attributed to J Gomes.

At least 37 records · Page 2Linked to original sources
PubMed1999

Screening of army soldiers for Wuchereria bancrofti infection in the metropolitan Recife region, Brazil: implications for epidemiological surveillance.

Between 1989 and 1995, blood surveys were performed for Wuchereria bancrofti infection in several barracks of the Brazilian army in the metropolitan Recife region. For initial screening, 60 microliters of capillary blood were examined for microfilaria. All men who tested positive had microfilaria quantified by filtration of venous blood through a polycarbonate membrane. Of 23,773 men screened, 585 (2.5%) had microfilaria (mf). Microfilarial density ranged from < 1-8706 mf/ml of blood. Thirteen individuals had ultra-low microfilarial densities (1 mf/11 ml of blood). Characterization of 174 autochthonous cases made it possible to map 8 new districts in 4 cities within metropolitan Recife region where transmission of W. bancrofti was previously unknown. Routine screening of soldiers in the military may provide important surveillance data for national programmes to eliminate transmission of W. bancrofti.

Adolescent↗
PubMed1999

Hepatic injury and disturbed amino acid metabolism in mice following prolonged exposure to organophosphorus pesticides.

Chronic occupational exposure to organophosphorus and carbamate-type pesticides significantly inhibits acetylcholinesterase activity and causes morbidity. This study on mice was designed to evaluate their amino profile and to identify signs of hepatic dysfunction following their chronic exposure to mixtures of organophosphorus pesticides. Laboratory mice were exposed to a formulated mixture of the six organophosphorus pesticides (Dimethoate, Chlorpyrifos, Profenofos, Pirimiphos methyl, Triazophos and Dimethoate) most commonly used in agriculture in this region of the Middle East. Doses (10% of LD50 of the mixture) were given once a week by gavage in corn oil for 7 weeks; the control group was given only corn oil. At the end of the exposure period, mice were culled and blood samples were collected to determine erythrocyte acetylcholinesterase activity, biochemical markers of liver function and concentrations of serum amino acids. Erythrocyte acetylcholinesterase activity and total serum proteins decreased significantly in the exposed group. Serum concentrations of alanine aminotransferase and aspartate aminotransferase, alanine, glutamic acid, glycine, isoleucine, leucine, methionine, ornithine, proline, serine, threonine and valine were significantly increased in the exposed mice, while serum levels of cystine were decreased significantly. There were also non-significant increases in serum alkaline phosphatase, gama-glutamyl transpeptidase and some of the other amino acids. Chronic exposure to mixtures of organophosphorus pesticides is associated with decreased acetylcholinesterase activity, hepatic dysfunction and disturbance of amino acids profile. Biochemical indices of hepatocellular injury and disturbed amino acid metabolism may be of value as markers of chronic exposure to such pesticides.

Acetylcholinesterase↗
PubMed1998

Fed-batch bioproduction of spectinomycin.

Actinomycetes produce about 67% of the known antibiotics covering a wide range of chemical structures. However, their filamentous growth present several problems during industrial processes. Among these problems oxygen transfer limitation is critical. In this chapter we present the role of oxygen in spectinomycin production by a Streptomyces species. Spectinomycin, a broad spectrum antibiotic effective against penicillin resistant gonorrhea, is an aminoglycoside constituted from two glucose moieties. Its bioproduction is strongly influenced by glucose and oxygen. We have shown that for a fixed dissolved oxygen concentration, there are two specific glucose concentrations which give maximum final titers of spectinomycin. The bi-modal maximum indicates the influence of two intermediate metabolites in spectinomycin biosynthesis. We propose a mechanism for spectinomycin biosynthesis and subsequently develop a model based on this mechanism. The proposed mechanism for spectinomycin biosynthesis is validated by successfully reconstructing the air flow rate profiles. A nonlinear systems theory technique termed External Differential Representation, is implemented to reconstruct the spectinomycin bioconversion process which then predicts the spectinomycin concentration from the air flow rate profile. This signifies that spectinomycin titers in industrial fed-batch processes can be controlled if a priori information about the air flow rate profile yielding maximum spectinomycin is available.

Glucose↗
PubMed1998

Clinical evaluation and applications of the Amplicor HBV Monitor test, a quantitative HBV DNA PCR assay.

Viral load has emerged recently as a reliable marker of disease progression and therapeutic efficacy in chronic infections, including AIDS and hepatitis C. The clinical management of type B hepatitis could also be improved by monitoring viremia levels in patients with chronic liver disease undergoing anti-viral treatment. To address this question we evaluated the performance of a newly developed, quantitative PCR assay (Amplicor HBV Monitor test, Roche Diagnostic Systems) in the assessment of viremia changes over time in a group of 45 patients with chronic active hepatitis (CAH) who received interferon treatment. Of the 45 patients, 14 were HBsAg and anti-HBeAg positive and 31 HBsAg, HBeAg positive. Follow-up extended up to 24 months. An average of ten samples per patient were analyzed for levels of ALT, IgM anti-HBc (Abbott Laboratories), HBV DNA by in-house dot-blot hybridization and hybridization-capture assays (HBV-DNA hybrid capture kit, Murex Diagnostics) and by Amplicor HBV Monitor. A sustained biochemical response was observed at the end of treatment in 12 HBeAg-positive and in seven anti-HBeAg positive patients. This was accompanied by the disappearance of HBeAg and of HBV DNA (hybridization assays) in all cases and by the clearance of IgM anti-HBc in 70% of the cases. Viremia (quantitative PCR assay) became undetectable only in 25-30% of cases and was associated with the loss of HBsAg. A good correlation was observed between the time course of IgM anti-HBc, quantitative PCR and dot-blot hybridization although the latter missed 33% of viremic samples. Together, these results indicate that the Amplicor HBV Monitor test is a robust and standardized assay for quantifying HBV viremia levels in the range from 10(2) to 10(7) copies/ml. Compared to other current markers, viral load may provide additional clinical information by predicting long term virologic response and HBsAg clearance in patients with normal ALT at the end of interferon therapy.

Adult↗
PubMed1998

Axial dispersion model for upflow anaerobic sludge blanket reactors

Fluid flow in UASB reactors is usually described by multicompartment models consisting of separate ideally mixed zones, plug flow zones, and stagnant zones linked with bypassing flows and back-mixing flows. A closer look at UASB reactor behavior indicates that this complexity is unnecessary. Our study on the startup and steady-state operation of a UASB reactor shows that its fluid flow can be explained just as well with a simple axial dispersion model. The physical transitions, which occur in different zones of the UASB reactor as the microorganisms acclimate to the wastewater, are adequately described by the model. Further, the number of parameters, which is six in standard UASB reactor models, is reduced to four in the case of the axial dispersion model.

Journal Article↗
PubMed1998

Morbidity among farm workers in a desert country in relation to long-term exposure to pesticides.

OBJECTIVES: Farm workers chronically exposed to low levels of pesticides seldom show signs and symptoms of clinical significance. This study investigates subclinical morbidity patterns among male farm workers in a desert country. METHODS: Migrant-established farm workers (N=226) were compared with referents (N=226) and with new farm workers (N=92) who had just entered the country to work on farms. Acetylcholinesterase activity was measured, the aiming test and digit symbol test were applied, and a morbidity profile was collected with a questionnaire. RESULTS: The erythrocyte acetylcholinesterase activity and hemoglobin-adjusted erythrocyte acetylcholinesterase activity were significantly depleted in the established farm workers. The results of the aiming and digit symbol tests were also significantly lower for the established farm workers. For the morbidity profile, irritated conjunctiva (47.3%), watery eyes (52.2%), blurred vision (63.3%), dizziness (55.2%), headache (63.7%), muscular pain (61.1%), and weakness (76.6%) were reported by established farm workers in statistically significantly higher numbers than by the referents and new farm workers. CONCLUSIONS: Morbidity patterns, such as the health complaints and objective parameters suggested in this study, would be suitable as criteria for identifying farm workers most at risk from pesticide toxicity and as criteria for initiating measures to control and reduce exposure.

Acetylcholinesterase↗
PubMed1997

Erythrocyte cholinesterase activity levels in desert farm workers.

In this study we have examined 532 migrant farm workers engaged mainly in the cultivation of vegetable crops, in both greenhouses and openfarms, and an equal number of controls. Erythrocyte acetylcholinesterase activity (AChE) was measured to determine the degree of toxicity due to exposure to organophosphate and carbamate pesticides in the farm workers employed either as foremen (41.5%) or farmers (58.5%). The mean ages of the farm workers and controls were 35.2 +/- 7.4 (mean +/- SD) years and 34.6 +/- 7.1 years. AChE activity of the farm workers and controls was 3.89 +/- 0.64 UI/ml (mean +/- SD) and 4.15 +/- 0.29 UI/ml. The haemoglobin adjusted erythrocyte cholinesterase activity (HAChE) was 29.96 +/- 4.14 (mean +/- SD) for farm workers and 32.10 +/- 2.26 for controls. AChE activity was very highly significantly lower for the foremen (3.76 +/- 0.69) compared to farmers (3.98 +/- 0.59) (Student's t-test = 4.13, p = 0.0001). HAChE was also very highly significantly lower for foremen (29.24 +/- 4.37) compared to farmers (30.46 +/- 3.88) (Student's t-test = 3.64, p = 0.0001). The poorly controlled used of pesticides in the farms appeared to have caused sub-clinical intoxication in the farm workers and indicated the need for training and implementation of hygiene practices.

Adult↗
PubMed1997

Abnormal endothelium-dependent responses in early radiation nephropathy.

While arterial hypertension and renal dysfunction are well recognized complications of renal irradiation, the mechanisms that trigger the development of these complications are unknown. Recently, it was reported that the endothelium is a major target in radiation injury. Because dysfunction of the endothelial cells may lead or contribute to the development of hypertension and renal dysfunction in radiation nephropathy, we tested the hypothesis that endothelium-dependent vasodilation is impaired in radiated kidneys prior to the onset of hypertension. To test this hypothesis, we used Long-Evans rats that had undergone left nephrectomy (3 weeks earlier) and irradiation (3000 r's) to the right kidney 8 days earlier (mean blood pressures in the irradiated rats were not different than in the controls). We then measured the changes in renal blood flow (RBF) induced by endothelium-dependent (acetylcholine and bradykinin) and -independent (nitroprusside, norepinephrine, and angiotensin II) vasoactive agents. We found that the increases in RBF induced by the endothelium-dependent but not independent vasodilators were markedly impaired in the irradiated kidneys. Blocking nitric oxide synthesis with nitro L-arginine methyl ester in sham rats mimicked the blunted responsiveness of the irradiated rats, whereas indomethacin (an inhibitor of prostaglandin synthesis) had no effect on either sham or irradiated rats. Finally, the RBF responses to the endothelium-independent vasoconstrictors, norepinephrine and angiotensin II, were not altered in the irradiated kidneys. These results suggest that renal irradiation causes endothelial dysfunction (prior to the onset of hypertension) but spares the vascular smooth muscle cells.

Acetylcholine↗
PubMed1995

Noise-induced hearing loss, nationality, and blood pressure.

Noise exposure has been associated with increased catecholamine production and blood pressure elevation in laboratory studies and in human volunteers. Epidemiologic studies have given conflicting results. In order to determine whether noise-induced hearing loss predicts a rise in blood pressure, we reviewed occupational medicine records in an occupational health center serving three companies where noise exposure is commonly found. Height, weight, blood pressure, and screening audiometry are obtained as part of routine occupational health screening, and the results of the screening visit are abstracted from written clinical records. The results of pure tone screening audiometry are reported in nonstandardized fashion (Normal, WNL, NAD, for example, for normal). We reviewed records from 1990 and 1991 inclusive. One investigator, blind to blood pressure status, assigned each record to "no hearing loss," "not codable," or "hearing loss assumed to be due to noise" on the basis of the written audiometry report. Hearing loss due to causes other than noise was considered not codable. No attempt was made to quantify severity of hearing loss. Two hundred and sixteen charts were excluded as "not codable," 1,535 were classified as having no hearing loss, and 610 had some degree of hearing loss, most probably due to noise exposure. To adjust for confounding covariates, multiple regression analysis was used and indicated that hearing status improves the regression model for predicting diastolic blood pressure (p = 0.04), following age, nationality, body mass index (BMI), and month of testing, although the effect is small. Stratification by age and BMI revealed increased diastolic pressure in the group with hearing loss under age 45, regardless of obesity.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1994

[Measles vaccination and age].

Recent studies have found administration of high-titre measles vaccine before 9 months of age to be associated with reduced survival. Since this suggests that early immunization could be unsafe, we examined the results of immunization campaigns with Schwarz standard measles vaccine carried out in 1980-1983 in three areas of Guinea-Bissau. Children were followed to death, migration or the age of five years. Children immunized at 4-8 months of age, of whom many were later re-immunized, had lower mortality between nine months and five years of age compared with children vaccinated at 9-11 months of age. The improved survival was unrelated to better protection against measles. There was no sign of socio-cultural differences between children immunized at different ages. Vaccination before 9 months of age is apparently safe and it may reduce childhood mortality compared with the currently recommended strategy of immunizing from nine months of age. Randomized trials are needed to confirm these observations which may have implications for the measles immunization strategy for developing countries.

Age Factors↗
PubMed1994

Smoking among health professionals.

A cross-sectional prospective study was conducted between the period December 1991 and November 1992, to identify the extent of smoking among practising doctors and other health professionals in general hospitals and health clinics in Al-Ain, United Arab Emirates. The study population consisted of 300 health professionals (doctors, specialists both clinical and non-clinical, pharmacists and dentists). They were handed self-administered questionnaires adapted from the World Health Organization standard questionnaire on smoking among health professionals. Among the responding 268 (89%) health professionals 197 (73.5%) were men, and 71 (26.5%) women. Among the men health professionals 86 (43.7%) were current smokers, 24 (12.2%) were ex-smokers and 87 (44.2%) were non-smokers, while among the women health professionals 4 (5.6%) were smokers, 1 (1.4%) was an ex-smoker and 66 (93%) were non-smokers. Doctors were uniformly aware of the detrimental effects of smoking, particularly its association with lung cancer, coronary artery disease, chronic bronchitis, and laryngeal cancer, and this was the major reason for their abstaining or wanting to quit the habit. The relationship of smoking with bladder cancer, soft tissue lesion (mouth and lip) and neonatal death was not well appreciated. Counselling patients about the hazards of smoking was practised significantly less often by doctors who smoked. The majority (83.6%) expressed the need for specific training for counselling patients to stop smoking. The options favoured by the health professionals for preventing smoking included a ban on tobacco advertising, specific health warnings on cigarette packets and restriction on smoking in public places, particularly in hospitals and clinics.

Adult↗
PubMed1993

Reduced childhood mortality after standard measles vaccination at 4-8 months compared with 9-11 months of age.

OBJECTIVE: To evaluate the impact on mortality of standard Schwarz measles immunisation before 9 months of age. DESIGN: Children vaccinated in 1980-3 at 4-5, 6-8, and 9-11 months of age were followed to migration, death, or the age of 5 years. SETTING: One urban district and nine villages in two rural areas of Guinea-Bissau. SUBJECT: 307 children vaccinated at 4-8 months and 256 at 9-11 months. MAIN OUTCOME MEASURES: Mortality from 9 months to 5 years of age for children immunised at 4-5, 6-8, and 9-11 months. RESULTS: Mortality was significantly lower in children vaccinated at 6-8 months than at 9-11 months (mortality ratio = 0.63, (95% confidence interval 0.41 to 0.97), p = 0.047). As vaccination was provided in semiannual or annual campaigns it is unlikely that age at vaccination reflected a selection bias. The trend was the same in all three study areas. Improved survival after early immunisation was not related to better protection against measles infection. With a Cox multivariate regression model to adjust for age, sex, season at risk, season at birth, measles infection, and region, children vaccinated at 4-8 months had a mortality ratio of 0.61 (0.40 to 0.92, p = 0.020) compared with children vaccinated at 9-11 months. Reimmunised children tended to have lower mortality than children who received only one vaccine (0.59 (0.28 to 1.27, p = 0.176)). CONCLUSION: Standard measles vaccination before 9 months is not associated with higher childhood mortality than is the currently recommended strategy of immunising from 9 months, and it may reduce mortality. This has implications for measles immunisation strategy in developing countries.

Age Factors↗
PubMed1993

Smoking habits among physicians in two Gulf countries.

The smoking habit of physicians in United Arab Emirates (UAE) and Kuwait were studied as first step towards surveying the habit among medical professionals. A cross-sectional survey was conducted in Kuwait between January-June 1990. Out of the 300 physicians who were contacted 252 (84%) completed the questionnaires, 190 (75%) were males and 62 (25%) were females. Among male physicians, current smokers were 86 (45.3%), ex-smokers were 34 (17.9%) and non-smokers were 70 (36.8%), while among the female physicians 10 (16%) were smokers and 52 (84%) were non-smokers. Also, a cross-sectional study was conducted between December 1991-November 1992 to identify the extent of smoking among physicians in UAE. Of the 300 physicians, 275 (91.6%) responded, 214 (77.8%) were males and 61 (22.2%) were females. Among the males, current smokers were 94 (43.9%), ex-smokers were 32 (14.9%) and non-smokers were 88 (41.2%), while among the females 5 (8.2%) were smokers, 3 (4.9%) were ex-smokers and 53 (86.9%) were non-smokers. Most important factors responsible for non-smoking doctors for not taking up smoking were: 'Protection of health', 'Self-discipline' and 'To set a good example to others'. The majority of physicians in UAE (91.3%) and Kuwait (75.6%) strongly agreed that smoking is hazardous to health. The results revealed that less than 50% of physicians provide information to over 70% of smoking patients. The majority of physicians and health professionals were aware of association between smoking and various diseases.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1992

The effect of stress and fatigue on cardiac rhythm in medical interns.

Twenty-four-hour ambulatory electrocardiographic monitoring was used to determine the incidence of arrhythmia while on-call and its relationship to stress and fatigue in 20 healthy medical interns. Mitral valve prolapse was present in 8 of 19 interns (42%). Heart rates ranged from a maximum of 103-167 beats/min (135 +/- 16) to a minimum of 38-61 beats/min (47 +/- 5). Interns had at least one episode of sinus tachycardia/h during 57% +/- 21% (range, 8-88%) of their hours on-call. Atrial premature beats (APB) were present in 19 of 20 (95%) and ventricular premature beats (VPB) in 12 of 20 (60%) subjects. APB/h ranged from 0 to 1.2 (0.4 +/- 0.3) and VPB/h from 0 to 23 (2 +/- 6). Three interns had multiform VPB and two had ventricular couplets. More APB/h occurred in interns under greater stress (0.5 +/- 0.4/h vs 0.3 +/- 0.1/h, p < 0.05) and combined stress and fatigue (0.6 +/- 0.4/h vs 0.2 +/- 0.2/h, p < 0.01). More VPB/h (5 +/- 9/h vs 0.5 +/- 0.6/h, p < 0.05) and higher (Lown) grade ventricular ectopy (2.3 +/- 1.6 vs 0.8 +/- 1.1; p < 0.05) occurred in interns under greater combined stress and fatigue. Mitral valve prolapse, sleep deprivation and caffeine intake were not associated with increased arrhythmia. The authors conclude that (1) rapid sinus tachycardia is frequent in interns while on-call and (2) interns experiencing greater stress and fatigue have more APB/h, VPB/h, and higher grade ventricular ectopy. These data support the notion that stress and fatigue may contribute to arrhythmia in healthy normal subjects.

Adult↗
PubMed1991

Antibody responses after immunization with killed oral cholera vaccines during the 1985 vaccine field trial in Bangladesh.

Sera collected during the 1985 oral cholera vaccine trial in Matlab, Bangladesh, which demonstrated efficacy of a whole cell combined with cholera B subunit vaccine (WC/BS) and a whole cell only vaccine (WC), were analyzed for antitoxin and vibriocidal antibodies. Before vaccines were given, antitoxin titers were highest in children, especially those with O blood group, whereas vibriocidal titers rose throughout life. Two weeks after three doses of vaccine, geometric mean antitoxin titers were 2.5-4.5 times higher in vaccinees who received the WC/BS vaccine; the vibriocidal titers were 1.3-2.1 times higher in vaccinees who received either vaccine. The titer elevations were relatively brief and were barely detectable 7 months after the third dose even though significant levels of protection persisted greater than or equal to 3 years. Thus, the oral vaccines induced a serum response in this large field trial that was similar to that seen in earlier pilot studies, but the duration of the serum responses was much shorter than the duration of the protection.

Administration, Oral↗