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Biomedical subjects

A P Dias

Publications and source records attributed to A P Dias.

12 recordsLinked to original sources
PubMed2001

Biting behaviour and potential vector status of anthropophilic blackflies in a new focus of human onchocerciasis at Minaçu, central Brazil.

Monthly collections were made of man-biting female blackflies: Simulium auripellitum Enderlein, S. guianense Wise, S. minusculum Lutz and S. nigrimanum Macquart (Diptera: Simuliidae) from four catching stations in the newly discovered focus of human onchocerciasis at Minaçu (13 degrees 35 minutes S 48 degrees 18 minutes W), 300 km north of Brasília in Goiás State. These provided baseline data on biting habits, population density and seasonal prevalence during the year before completion of the Serra da Mesa hydroelectric dam on the Rio Tocantins near Minaçu, in a project investigating the effect of dam construction on onchocerciasis transmission in the area. All four simuliid species were most abundant during the dry season, and only bit in low numbers (S. auripellitum S. minusculum, S. nigrimanum) or were absent (S. guianense) in the wet season. Simulium minusculum was the predominant species at all catching stations, being particularly abundant by the large River Tocantins. The other three species were mainly associated with smaller rivers. In the dry season, biting rhythms of S. minusculum varied with catching site, while S. nigrimanum showed peaks of activity in early morning and during the afternoon. Experimental infection with Onchocerca volvulus (Leuckart) (Nematoda: Onchocercidae), from a human volunteer, showed that this parasite could develop fully in the four simuliid species, which are all considered to be potential vectors in the area.

Animals↗
PubMed1997

Miconazole lacquer in the treatment of denture stomatitis: clinical and microbiological findings in Chinese patients.

OBJECTIVE: To investigate the efficacy of a miconazole lacquer in producing mycological and clinical cure of Candida-associated denture stomatitis in a Chinese cohort and to study the microbiology of the conditions. DESIGN: A cross-sectional study of the clinical and microbiological features of the condition and its response to treatment with the lacquer. SUBJECTS AND METHOD: Twenty-one Chinese adults with palatal erythema; 15 denture wearers matched for age and sex as controls for microbiology. Clinical examination, impression for culture, photograph of palate to monitor response to treatment, and lacquer application on upper denture base on days 0, 7 and 14. Impression and photograph repeated on day 21; impression cultures quantified by image analysis. Palatal impression in controls; dummy impression as control for impression culture procedures. MAIN OUTCOME MEASURES: Severity of lesion, incidence and type of microorganism at presentation and during treatment; qualitative and quantitative assessment of yeast growth; the latter by statistical analysis of pixel units of yeast colonies; correlation of clinical and mycological cure. RESULTS: Out of the 21 lesions (16 Newton's stage I and 5 stage II), 57% had yeasts at presentation, 10% coliforms and 33% no significant growth. Clinical cure in 3 weeks in 71%, mycological cure in 75% in 7 days; clinical and mycological cure coincided only in 43%. Polymicrobial growth of yeasts and coliforms throughout the course in some. CONCLUSIONS: Miconazole lacquer was a viable treatment option for Candida-associated denture stomatitis in this adult, Chinese cohort; microbiology comprised yeasts, mainly C. albicans and coliforms, especially Klebsiella and Enterobacter species; the pathogenic role of the latter is questionable.

Adult↗
PubMed1997

Activity and stability of a Rhizomucor miehei lipase in hydrophobic media.

The effects of detergents and organic solvents on a commercial lipase (Lipozyme) from Rhizomucor miehei were investigated. It was shown that the detergent sodium cholate is possibly an activator of the enzyme, increasing lipase activity 2.5 times (250% of the control) when the enzyme was preincubated with 7 mM cholate. Lipozyme activity was over twice as high (230% of the control) in the presence of 80 mM Tween 80 or 90 mM Tween 20 (polyoxyethylenesorbitan monolaurate), apparently through an additional emulsifying action on the substrate. Preincubation with Tween 80 (polyoxyethylenesorbitan mono-oleate) did not affect enzyme activity. In contrast, lipase activity was completely inhibited in the presence of an 8.9 mM concentration of another non-ionic detergent, Brij 58, whereas with a 16.4 mM concentration of the cationic detergent cetyltrimethylammonium bromide (CTAB), enzyme activity was reduced by 80%. Preincubation of Lipozyme with the same concentrations of Brij 58 [poly(oxyethylene)20 cetyl ether] and CTAB promoted total inactivation of the enzyme. Organic solvents had different effects on lipase activity and stability. Of the tested solvents, hexane was least deleterious to lipase activity and did not alter enzyme stability on preincubation. These results suggest that Lipozyme can be used in esterification reactions with hexane as solvent or in hydrolysis reactions with Tween 20 or Tween 80 as emulsifying agents, after pretreatment with sodium cholate.

Culture Media↗
PubMed1996

Four new cytotypes of the onchocerciasis vector blackfly Simulium guianense in Brazil.

Simulium (Trichodagmia) guianense is an important Amazonian vector of onchocerciasis. Examination of the polytene chromosome banding patterns of larvae from five sites in Brazil revealed the occurrence of four cytotypes, designated A, B, C and D. The chromosomal standard, Simulium guianense A, occurred at two localities in Goias State (on the Rio Tocantins and Rio Mucambão) where it was the only cytotype. The other three sites examined yielded one different cytotype from each: B from Rio Oyapoque in Amapa State, C from Rio Tocantins in Maranhão State, and D from Rio Xingu in Para State. All cytotypes differed by at least two fixed inversions, but a sex determining system was not evident in any cytotype. As the cytotypes have been found allopatrically it is not certain that they represent sibling species; sampling of sympatric populations would resolve this. During certain times of the year, voracious anthropophagy by S.guianense sensu lato occurs at the localities sampled for cytotypes A, C and D (biting data are not available for the cytotype B locality). In some other areas, however, S.guianense s.l. is entirely zoophilic. Further studies are needed, therefore, to elucidate the biting habits, vectorial capacity, geographic distribution and taxonomic status of these four, and perhaps additional, cytotypes comprising the S.guianense complex.

Animals↗
PubMed1995

Clinical, microbiological and ultrastructural features of angular cheilitis lesions in Southern Chinese.

OBJECTIVE: To obtain baseline data on angular cheilitis in Southern Chinese. DESIGN: A cross-sectional investigation of the clinical, microbiological and ultrastructural features of the condition. SUBJECTS AND METHOD: Thirty six Chinese adults with angular cheilitis; 28 controls matched for age and sex, with no inflammation. Clinical examination, swabs of lesions for microbiology, impressions of lesions for ultrastructure, using replica technique. MAIN OUTCOME MEASURES: Severity of lesions, associated signs and symptoms, incidence and type of microorganisms, ultrastructural features. RESULTS: Of a total 68 lesions 32 were bilateral and four unilateral. Forty four (65%) were mild (Type I) and the remaining 24 (35%) moderate (Type II). Infective agents were isolated from 37 (54%) lesions; pure growth of Candida spp and Staph. aureus was noted in nine lesions each; a mixed growth of the two in II, beta-haemolytic streptococci in three and a mixed flora including coliforms in the other five. Candida spp were present in one control, beta-haemolytic streptococci in two and coliforms in four others. Scanning electron microscopy revealed natural topography of the angular skin with sparse colonisation by bacteria and yeasts. CONCLUSIONS: Angular cheilitis in Southern Chinese seems to be characterised by a milder clinical presentation and classic infective agents of the disease: Candida spp and Staph. aureus.

Adult↗
PubMed1987

The status of Simulium oyapockense and S. limbatum as vectors of human onchocerciasis in Brazilian Amazonia.

In an attempt to explain the current distribution of onchocerciasis in the forests of northern Brazil (Moraes et al., 1979, 1986), and its potential for dispersal to other areas, this study compares the vector status of Simulium oyapockense Floch and Abonnenc, 1946 in both a hypoendemic and an onchocerciasis free area with that of S. limbatum Knab, 1915 in the latter area. Both species allowed the full development of Onchocerca volvulus (Leuckart) to the infective L3 stage after experimental infection with microfilariae. Their vector competence was significantly lower than for other efficient vector species in South America and Africa because of the lethal effect of the cibarial armature on ingested microfilariae. The low vector capacity of S. oyapockense, together with the low prevalence and intensity of infection of O. volvulus, probably explains why onchocerciasis has not significantly increased in intensity over the last 10 years in the hypoendemic part of the Amazonian focus. Omnipresence of both vector species in the adjacent savanna region, however, could facilitate the spread of onchocerciasis if human population movements continue from the hyperendemic part of the onchocerciasis focus.

Animals↗
PubMed1987

A rationale for selecting suitable physiology topics for the basic sciences curriculum in dentistry.

The suitability of physiology topics taught in the first-year dental curriculum needs to be investigated in the light of the view of the present generation of clinical and preclinical teachers, and students. This was studied in the University of Malaya in order to propose a rational physiology curriculum with proper identification of priority topics. Oral physiology, blood and the cardiovascular system were found to be the most relevant for dental students. Among the systems, high and low priority topics were identified and their relative importance is discussed.

Attitude of Health Personnel↗
PubMed1983

The concentration of Mansonella ozzardi microfilariae in skin capillaries.

The densities of microfilariae of Mansonella ozzardi in different regions of the body of infected individuals were studied. The density in venous blood closely approximated to that found in finger capillaries, but was significantly lower than the densities in capillaries of the scapular region and buttocks. A possible explanation for this concentration of microfilariae is the lack of glomi in these two sites, which consequently have a lower flow of blood than areas where glomi occur and where microfilarial densities are lower. No relationship was found between blood and skin densities in the buttocks and scapular region, probably due to the inadequacy of the skin snip method used for the detection of this species of filaria. It was concluded that the most acceptable detection method for M. ozzardi remains the sampling of finger capillary blood. It could not be decided, due to the paucity of data, whether any relationship exists between skin microfilarial densities and the biting sites of the vectors.

Adolescent↗
PubMedDate not supplied

Identification of vector species (Diptera:Simuliidae) of human onchocerciasis in the amazonia focus of Brazil and Venezuela.

The taxonomic status of three Amazonian simuliid species, Simulium guianese Wise, S. oyapockense Floch & Abonnenc and S. yarzabali Ramirez Perez is reviewed. Simulium cuasisanguineum Ramirez Perez, Yarzabal & Peterson is synonymized with S. oyapockense, and S. yarzabali is revalidated from its synonymy with S. incrustatum Lutz. The role of these three species in the transmission of human onchocerciasis and mansonelliasis in Amazonia is reviewed.

Animals↗