Effectiveness of repellent/insecticidal bars against malaria and filariasis vectors in peninsular Malaysia

Field tests were conducted to compare the degree of protection from bites of Mansonia species and Anopheles maculatus by applying two repellent/insecticidal bars, MOSBAR and MOSKIL, to exposed arms and legs. Human test subjects were exposed to natural populations of mosquitos for an 8-hour night time period while using the repellent/insecticidal bars. MOSBAR gave good protection against the bites of Mansonia and An. maculatus. MOSKIL was effective against An. maculatus but not against Mansonia. High mortality was observed among the mosquitos collected from human test subjects treated with the repellent/insecticidal bars. Use of MOSBAR in terms of cost-effectiveness and safety by field and health workers entering into malaria and filariasis endemic areas is discussed.     

Thrombocytopenia in dogs induced by granulocyte-macrophage colony- stimulating factor: increased destruction of circulating platelets

Administration of recombinant canine granulocyte-macrophage colony- stimulating factor (rcGM-CSF) to normal dogs in previous studies induced an increase in peripheral blood neutrophils and a dose- dependent decrease in platelet counts. In six dogs that received the highest tested dose of rcGM-CSF (50 micrograms/kg/d) for a minimum of 12 days, the mean nadir of the platelet count was 46,000/microL (range, 4,000 to 91,000/microL) on day 9 +/- 1.1 after starting therapy, compared with a mean baseline platelet count of 398,000/microL (range, 240,000 to 555,000/microL). In three dogs, survival of autologous 111In- labeled platelets was reduced from a mean of 4.9 days to 1.3 days during the administration of rcGM-CSF. Biodistribution studies with gamma camera imaging indicated that there was an increase in mean hepatic uptake during the administration of rcGM-CSF, from 15% to 44% of the total injected 111In-labeled platelets at 2 hours, whereas splenic uptake was not significantly changed. In contrast, in two evaluable dogs who were recipients of 111In-labeled platelets from matched allogeneic donors receiving rcGM-CSF, platelet survival was not reduced and no increased hepatic uptake was noted. A third dog became alloimmunized to the matched donor platelets and was not evaluable. Immunohistologic studies of liver and spleen were performed with monoclonal antibodies specific for canine gpIIb/IIIa and P-selectin in dogs treated with rcGM-CSF and compared with untreated controls. On treatment, a marked reduction of platelets in the red pulp of the spleen was evident, and in general, the presence of platelet antigen in the liver was unchanged. Therefore, platelets were not being sequestered, but destroyed in the liver and spleen. The platelet antigens, P-selectin and gpIIb/IIIa, were identified in association with Kupffer cells in the liver, but no difference in the number of distribution of these Kupffer cells was found between controls and rcGM- CSF-treated dogs. In the spleen during rcGM-CSF treatment, most platelet antigens were associated with large mononuclear cells in the marginal zone. During administration of rcGM-CSF, CD1c and CD11c expression was increased on Kupffer cells. Platelet P-selectin expression and binding of leukocytes to circulating platelets were unchanged from baseline studies with rcGM-CSF treatment. In conclusion, during the administration of rcGM-CSF to dogs, a local process in the liver and spleen is induced resulting in thrombocytopenia.(ABSTRACT TRUNCATED AT 400 WORDS)     

Evaluation of lung function in Singapore obese children

In this study, 65 obese children with a mean age of 12.1 years and mean relative weight (RW) of 156.1% had their lung function evaluated in comparison to predicted normal values. There were substantial changes in forced expiratory flow rates (FEF's) and maximum voluntary ventilation (MVV), with reductions to between 60% to 70% of predicted normal values. The more obese children (RVV greater than or equal to 150%) had significantly lower FEF's and MVV and a significantly greater proportion of the more obese children had FEF50 and MVV of less than 60% of predicted normal values. The results were suggestive of narrowing of small airways and increased respiratory inertance possibly due to excessive accumulation of fat in the chest wall and abdomen leading to respiratory limitation.     

Comparison of fractionated to single-dose total body irradiation in conditioning canine littermates for DLA-identical marrow grafts

We explored the ability of fractionated total body irradiation (TBI) given at a rate of 7 cGy/min from opposing dual 60Co sources at otherwise lethal doses of 450, 600, 700, 800, and 920 cGy to condition dogs for marrow grafts from DLA-identical littermates. Results were compared with those of a previously reported study using single-dose TBI administered under otherwise identical conditions. Fractionated TBI was less immunosuppressive than single-dose TBI, as evidenced by a significantly higher rate of graft rejection (P = .001). Specifically, sustained allogeneic engraftment was observed in only two of 18 (11%) dogs that received 600 to 800 cGy fractionated TBI as compared with 11 of 17 (65%) dogs that received comparable doses of single-dose TBI. Only at 450 cGy (none of the ten dogs studied had sustained engraftment) and at 920 cGy (four of five dogs that received fractionated and 20 of 21 dogs that received single-dose TBI engrafted) were we unable to find differences between the two modes of radiation. Most dogs that rejected their graft survived with autologous recovery (13 of 22 that received fractionated and eight of 12 that received single-dose TBI; P = .49), presumably the result of extended support provided by the transient allogeneic grafts. We conclude that at equivalent doses fractionated TBI is significantly less effective than single-dose TBI to condition DLA-identical littermate dogs for marrow transplantation. These findings have implications for the design of conditioning programs in clinical transplantation, especially when T- cell-depleted marrow grafts are used.     

Microglia Responses in the CNS Following Sciatic Nerve Transection in C57BL/Wldand BALB/c Mice

The present study employed C57BL/Wld^smice to investigate whether a delay in microglia reaction would occur similar to the delay that occurs in macrophage response after sciatic neurectomy. The results were compared with control BALB/c mice. The observations showed that in both strains of mice there was no delayed microglia response around lesioned motoneurons and around the central processes of the dorsal root ganglion cells after sciatic neurectomy in the adult. The increased Mac-1 staining appeared as early as 1 day postoperation (dpo). This indicates that microglial cells and macrophages respond to different signals generated by neurectomy. In both strains of mice, the number of microglia in the neonate was much less than that in the adult and the increase in Mac-1 staining was detectable only at 3 dpo in both strains of mice. A significant loss of motoneurons was detected after sciatic neurectomy in the neonate. However, there were no significant differences in the mean percentages of motoneuron loss between the two strains of mice at 5, 10, and 15 dpo. It is surmised that the lack of an adequate number of mature microglia in the neonates and their tardy expression of CR3 antigenicity may contribute to the motoneuron loss.     

Evaluation of Amplicor- and IS6110-PCR for direct detection of Mycobacterium tuberculosis complex in Singapore

One hundred and seventy-eight samples from 168 individuals were tested for Mycobacterium tuberculosis complex ( Mtc ) using Amplicor PCR, IS6110 -PCR (in-house), acid fast (AF)-staining and culture. Thirty-one samples were positive by culture, but 37 samples were later resolved to be truly positive for Mtc . Of these, Amplicor detected 32 (86.5%), IS6110 -PCR detected 31 (83.6%), and AF-staining 21 (56.8%). None of the 141 Mtc -negative samples was positive by these tests, thus giving 100% specificity. Although the IS6110 -PCR was more sensitive than Amplicor in detecting spiked Mtc DNA, it was not more sensitive than the latter in detecting Mtc in clinical samples. Reasons likely to account for the PCR false negativity were (i) sample inoculum size, (ii) nonuniform samples due to clumping effect of Mtc and (iii) the absence of target gene sequences for IS6110 -PCR. Culture negativity, on the other hand, was likely to be associated with nonviable Mtc . Amplicor PCR is promising for direct detection of Mtc . The IS6110 -PCR, however, may not be as suitable because of possible existence of IS6110- deleted Mtc strain in Singapore.     

Small granule-containing cells in the heart of the toad (Bufo melanostictus)

This study reveals the presence of small granule-containing cells in the heart of the toad, Bufo melanostictus. The cells were small in size (5-25 microns in diameter) and located in the interatrial septum. The small cells occurred singly or in small clusters within the cardiac ganglia or near the myocardial cells. They were characterized by numerous large dense core vesicles (80-300 nm) in their cytoplasm. With 5-hydroxydopamine treatment, the granularity of the large dense core vesicles was greatly intensified. The large dense core vesicles were variable in size and shape and extended into the long and short processes of the cells. Some of these processes were in close contact with myocardial cells. Other cytoplasmic organelles included rough endoplasmic reticulum, free ribosomes, randomly distributed mitochondria and glycogen particles. Individual cells or cell clusters were usually ensheathed by a thin layer of cytoplasm from sheath cells. The small granule-containing cells in the present study correspond to the catecholamine-containing (SIF) cells described by earlier workers. These cells presumably regulate muscular and ganglionic activities by virtue of their close association.     

Multicentre evaluation of a direct coagglutination test for group A streptococci

A coagglutination test for detection of group A streptococci in throat samples was evaluated in a multicentre study and found to be about 95 % sensitive when applied to swabs taken from symptomatic patients which yielded more than 100 colonies per plate on culture. The sensitivity of the test dropped significantly when it was applied to swabs giving fewer than 100 colonies on culture. The specificity of the test was high regardless of colony count on conventional media.     

Dermatoglyphs in children with mitral valve prolapse.

The dermatoglyphs of 50 Singapore school children with mitral valve prolapse (MVP) were studied, with special reference to the frequency of digital arches. The MVP was diagnosed clinically and substantiated by two dimensional echocardiography. In the study there were 35 Chinese and 15 Malay children, with ages ranging from 6 to 19 years. Four Chinese children had one or more arches on the digits but none of the Malay children was found to have arches. It was shown that the frequency of arches on the digits was not significantly higher than that among 50 controls (who were shown not to have MVP on two dimensional echocardiography) or when compared with the frequency of arches among the Chinese and Malay population in Singapore (2.0% and 2.9% respectively). No other dermatoglyphic abnormalities (including atd angle) were found.