Biomedical subjects
Publications and source records attributed to S Sulaiman.
Three pyrethroids were evaluated in the laboratory against Aedes albopictus females by exposure to insecticide impregnated papers, and to 4th instar Ae. albopictus larvae as insecticide solutions. Lambda-cyhalothrin was found to be the most effective pyrethroid when tested against Aedes albopictus adult females and larvae compared with that of deltamethrin and permethrin.
There was high mortality in late larval instars of Aedes albopictus (Skuse) from laboratory and field populations in the 24 h after application of three Bactimos formulations of Bacillus thuringiensis H-14. Mortalities were higher and residual effects longer in field populations than in laboratory ones. Briquets were the most effective formulation (mortality 96-100% after five weeks; 76-92% after eight weeks). Culex quinquefasciatus Say larvae were tested only against the briquet formulation. In the laboratory, 100% mortality of late instars persisted for six weeks and dropped to 48-88% after eight weeks. In the field, late instars were reduced by 62-87% after 24 h and 69-72% after one week compared to increases in an untreated population of 160% and 176% respectively.
Nine species of parasitoids were found parasitizing the pupae of filth flies breeding in refuse dumps and poultry farms throughout peninsular Malaysia. Spalangia were most common, consisting of Spalangia endius Walker, S. cameroni Perkins, S. gemina Boucek, S. nigroaenea Curtis, and two undescribed species. Other parasitoids collected were Pachycrepoideus vindemmiae Rondani, Dirhinus himalayanus Westwood, and an unidentified Hymenoptera. The parasitized fly hosts included Musca domestica L., Chrysomya megacephala (F.), Fannia sp., and Ophyra sp. S. endius was the most common parasitoid attacking M. domestica and C. megacephala at refuse dumps and poultry farms D. himalayanus were found to parasitize only M. domestica pupae collected at poultry farms.
The role of some adult flies (Diptera: Cyclorrhapha) as carriers of helminth parasites of man was studied at four sites in Malaysia: a refuse dump, where no helminth-positive flies were detected, and in three peri-domestic situations where four species of flies carried up to three types of nematodes. The dominant fly species Chrysomya megacephala (Fabricius) carried eggs of the roundworm Ascaris lumbricoides L., the pinworm Trichuris trichiura (L.) and hookworm on the adult external body surface and in the gut lumen, in association with Bukit Lanjan aborigines. Chrysomya rufifacies (Macquart) and Sarcophaga spp. also had Ascaris lumbricoides and Trichurus trichiura eggs in their gut contents. Human helminths were not recovered from Lispe leucospila (Wiedemann), Lucilia cuprina (Wiedemann) or the housefly Musca domestica L. In an urban slum area of Kuala Lumpur city, filariform larvae identified as the hookworm Necator americanus (Stiles) occurred in the intestines of the face-fly Musca sorbens Wiedemann (22 larvae per 100 flies) and of Chrysomya megacephala (4.5 larvae per 100 flies). This concentration of apparently infective N. americanus in M. sorbens, a fly which often breeds in faeces and browses on human skin, could have transmission potential.
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1. Seven types of water-insoluble adhesives were evaluated in sticky traps for collecting adults of Musca domestica L. and Chrysomya megacephala (Fabricius) or mosquito larvae (Aedes aegypti (L.) and Culex quinquefasciatus Say). 2. Adhesive viscosity affected the tackiness of the glues and this determined their trapping efficiency in air or water. 3. From the 'Hyvis' range of adhesives tested, 'Hyvis 200' was most effective for trapping adult flies. 4. With 24 h exposure to fourth instar Ae.aegypti larvae in tapwater, submerged plates coated with 'Hyvis 10', 'Hyvis 30' or 'Hyvis 200' formulations trapped the majority of larvae. In polluted water the highest rates of trapping were 17.3% of Ae.aegypti and 18.7% of Cx quinquefasciatus with 'Hyvis 200'. Floating traps were consistently less productive than submerged traps under laboratory conditions. 5. In a heavily polluted natural breeding-site of Cx quinquefasciatus, floating traps were more productive than submerged sticky traps with four of seven adhesives tested, the most efficient being 'Hyvis 200' (4.2 mosquitoes per hour) and Hyvis:polyethylene 90:10 (4.5/h). Despite the relative inefficiency of aquatic traps, emergent adults, pupae and second to fourth instars of larvae were collected quickly from the habitat.
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Fresh samples of human urine adjusted to pH 6.8 were rapidly evaporated at 37 degrees C to 1,250 mosmol/kg. The calcium phosphate precipitated was washed and the calcium measured by flame atomic absorption spectrophotometer. This procedure was found to be reasonably reproducible. When macromolecules were first removed by ultrafiltration the precipitated calcium was reduced by 76.9%. Addition of human Tamm-Horsfall mucoprotein (T-H) to the urine ultrafiltrates prior to evaporation largely but not completely restored the precipitated calcium. Clumping of crystals was studied quantitatively by passage through a nylon mesh. Mean retention on the mesh was strikingly reduced after ultrafiltration and increased by addition of T-H to the ultrafiltrates. These findings support the view that T-H triggers calcium phosphate crystal formation and clumping in whole urine.
Different proportions of mixtures of whole urine and its ultrafiltrate were evaporated to 1,250 mosm/kg to study crystal formation of calcium oxalate at pH 5.3 and calcium phosphate at pH 6.8. At both pH values there was a direct linear relationship between proportion of whole urine and crystal formation. When sodium dodecyl sulphate was added to whole urine before evaporation, calcium oxalate and calcium phosphate crystal formation were reduced to 64.3 and 53% respectively of the values of whole urine. This favours the proposition that crystal formation is promoted by polymeric uromucoid.
Macromolecules were removed from whole urine samples by sequential ultrafiltration using molecular weight cut-offs of 300,000, 100,000 and 10,000 dalton. The whole urine samples and ultrafiltrates were evaporated to 1,250 mosm/kg at pH 5.3 and 6.8 to study calcium oxalate and calcium phosphate crystal formation, respectively. While all the ultrafiltrates removed Tamm-Horsfall proteins and most of the crystal formation, there was some 10% of the crystal-promoting powers in the macromolecules in the fraction between molecular weight 100,000 and 300,000 dalton. This demonstrates the existence of a second crystal-promoting substance in the macromolecules of whole urine.
1) Low pyrophosphate urine was generated by passage through a nylon coil bearing immobilised inorganic pyrophosphatase. High pyrophosphate urine was made by addition of inorganic pyrophosphate. 2) Urine samples of low, normal, and high pyrophosphate content were rapidly evaporated at 37 degrees C to 1,050 or 1,250 mosmol/L and the crystals formed studied by microscope, isotope and chemical methods. 3) Urinary pyrophosphate level had no significant effect upon calcium oxalate crystals formed in whole urine at pH 5.3 or 6.1, or calcium phosphate crystals formed at pH 6.8.
Crystal formation in whole urine was studied by the technique of rapid evaporation to 1,250 mosmol/l with and without raising citrate concentration by 40-50%. The added citrate reduced calcium oxalate crystal formation at pH 5.3 by about 25% and reduced calcium phosphate crystal formation at pH 6.8 by some 42%. These results support the view that citrate is important in maintaining calcium in solution in whole urine, and that raising the urinary citrate could be effective treatment for calcium oxalate/phosphate urolithiasis.
Three techniques, namely a ladle, a metal quadrat and a D-shaped aquatic net, were used for comparison to sample immature stages of mosquitoes in woodland pools in northern England. The quadrat proved to be more reliable in giving a more accurate representation of the different instar proportions in the ponds than the ladle and aquatic net. The ladle showed bias of undersampling the earlier instars. Similar but not so severe bias also occurred for the D-net.
The technique of rapid evaporation of whole urine to standard osmolality has been studied further and quantitative measurements made of the calcium oxalate crystals resulting, firstly by a microscope method and secondly by isotope method using 14C-oxalate. It is confirmed that ultrafiltration of urine prior to evaporation leads to a large reduction in calcium oxalate crystal formation and that this is largely restored by addition of human urinary Tamm-Horsfall protein (uromucoid). Albumin does not have this effect.
1. A low urinary magnesium was induced in normal volunteer subjects by giving cellulose phosphate; magnesium was added in vitro to yield urine samples of normal and high magnesium concentrations. 2. After rapid evaporation of these urine samples at pH 5.3 to standard osmolality the calcium oxalate crystals were measured by microscopy and isotopic methods. 3. There was a clear inverse correlation between magnesium concentration and calcium oxalate crystal formation. 4. The case for treating calcium oxalate urolithiasis with magnesium is strengthened.
1. Samples of fresh human urine were treated with immobilized uricase to lower urate concentration. Urate was added to yield low, normal and high urate samples. 2. Each sample was rapidly evaporated at pH 5.3 to standard osmolality and the yield of calcium oxalate crystals measured either by semi-quantitative microscopy or fully quantitative radioisotope techniques. 3. Increase of urinary urate did not increase the calcium oxalate crystals formed and may even have had an opposite effect. 4. Allantoin was without significant effect upon calcium oxalate crystal formation. 5. These data provide no support for the suggestion that reducing urate concentrations in the urine may be of value in treatment of patients with calcium oxalate stones.
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