LIGAND-INDUCED MOVEMENT OF LYMPHOCYTE MEMBRANE MACROMOLECULES : III. RELATIONSHIP BETWEEN THE FORMATION AND FATE OF ANTI-IG-SURFACE IG COMPLEXES AND CELL METABOLISM

Spleen lymphocytes were studied for the movement and interiorization of complexes of anti-Ig-surface Ig. The movement of the complex into a small, compact zone of the cell membrane (forming a cap) was inhibited by drugs that inhibited glycolysis and oxidative phosphorylation, but not by drugs that affected protein synthesis. Dead lymphocytes did not form caps. Freeze-etching techniques revealed that inhibited lymphocytes showed formation of multiple small complexes over the entire cell surface. Inhibitors of glycolysis and of oxidative phosphorylation also inhibited the interiorization and catabolism of radioiodinated anti-Ig. We hypothesize that cross-linking of all the surface Ig triggers the membrane movements that are required to pull the lattice into one zone of the cell

A comparative study on the epidemiology and immuno-pathology of bovine tuberculosis in Bos indicus and Bos taurus cattle in Ethiopia

AbstractBovine tuberculosis is a disease of dual effect, having public health and economic implications. The present study was conducted on its epidemiology and immuno-pathology in Holstein and Zebu breeds of cattle. Skin test, post mortem examination and pathology scoring, bacteriology, whole blood gamma interferon assay, ELISPOT assay, and lateral flow assay were used. An overall prevalence of 13.5% (n=5,424) was recorded; both prevalence (2 =61.8; P<0.001) and severity of pathology (mean pathology scores + SEM: 6.84±0.79 vs. 5.21±0.30; P=0.018, Mann-Whitney test) were significantly higher in Holstein than in Zebu. Similarly, IFN- responses to avian PPD (0.490.10 vs. 0.390.07), bovine PPD (0.630.11 vs. 0.430.07), or the ESAT6-CFP10 protein cocktail (0.430.01 vs. 0.300.05) were significantly higher (for all antigens: p<0.02) in Holstein than in Zebu cattle. However, both Holstein and Zebu exhibited similar T cell and antibody responses to different mycobacterial antigens i.e. no repertoire difference was observed between the two breeds. Thus, the present study showed increased susceptibility of Holsteins to bovine TB as compared to Zebu, similarity between Holsteins and Zebus in their antigen responses, and a positive correlation between IFN- responses and severity of pathology of bovine TB. [Ethiop.J.Health Dev. 2008;22(Special Issue):132-134

Insecticide resistance in Anopheles arabiensis (Diptera: Culicidae) from villages in central, northern and south west Ethiopia and detection of kdr mutation

<p>Abstract</p> <p>Background</p> <p><it>Anopheles arabiensis </it>is the major vector of malaria in Ethiopia. Malaria vector control in Ethiopia is based on selective indoor residual spraying using DDT, distribution of long lasting insecticide treated nets and environmental management of larval breeding habitats. DDT and pyrethroid insecticides are neurotoxins and have a similar mode of action on the sodium ion channel of insects. It was therefore necessary to verify the insecticide susceptibility status of <it>An. arabiensis</it>, to better understand the status of cross-resistance between DDT and the pyrethroids in this species as well as to detect a resistant gene.</p> <p>Methods</p> <p>Standard WHO insecticide susceptibility tests were conducted on adults reared from larval and pupal collections from breeding sites at three villages namely: Sodere in the Rift Valley, Gorgora in the north and Ghibe River Valley in the south west of Ethiopia. The occurrence of cross-resistance between pyrethroids and DDT was determined using a DDT selected laboratory colony originally collected from Gorgora. Phenotypically characterized mosquitoes were tested for the presence of knockdown resistance (<it>kdr</it>) alleles using the standard polymerase chain reaction assay.</p> <p>Results</p> <p>All <it>An. gambiae </it>s.l. specimens assayed by PCR were identified as <it>An. arabiensis</it>. The knockdown and mortality results showed <it>An. arabiensis </it>resistance to DDT in all villages, resistance to deltamethrin and permethrin in the Ghibe River Valley and permethrin resistance in Gorgora. Bioassay susceptibility tests also indicated the presence of cross-resistance between DDT and permethrin, but not between DDT and deltamethrin. The knockdown resistance <it>(kdr) </it>mutation of leucine to phenylalanine in the sodium ion channel gene was detected in populations from Gorgora and the Ghibe River Valley.</p> <p>Conclusion</p> <p>Since <it>An. arabiensis </it>shows high levels of resistance to DDT in all villages tested and varying pyrethroid resistance in Gorgora and the Ghibe River valley, precautionary measures should be taken in future vector control operations. Moreover, the status of resistance in other locations in Ethiopia and the spread of resistant gene (s) should be investigated.</p

Chloroquine-resistant Plasmodium vivax malaria in Debre Zeit, Ethiopia

<p>Abstract</p> <p>Background</p> <p><it>Plasmodium vivax </it>accounts for about 40% of all malaria infection in Ethiopia. Chloroquine (CQ) is the first line treatment for confirmed <it>P. vivax </it>malaria in the country. The first report of CQ treatment failure in <it>P. vivax </it>was from Debre Zeit, which suggested the presence of chloroquine resistance.</p> <p>Methods</p> <p>An <it>in vivo </it>drug efficacy study was conducted in Debre Zeit from June to August 2006. Eighty-seven patients with microscopically confirmed <it>P. vivax </it>malaria, aged between 8 months and 52 years, were recruited and treated under supervision with CQ (25 mg/kg over three days). Clinical and parasitological parameters were assessed during the 28 day follow-up period. CQ and desethylchloroquine (DCQ) blood and serum concentrations were determined with high performance liquid chromatography (HPLC) in patients who showed recurrent parasitaemia.</p> <p>Results</p> <p>Of the 87 patients recruited in the study, one was lost to follow-up and three were excluded due to <it>P. falciparum </it>infection during follow-up. A total of 83 (95%) of the study participants completed the follow-up. On enrolment, 39.8% had documented fever and 60.2% had a history of fever. The geometric mean parasite density of the patients was 7045 parasites/μl. Among these, four patients had recurrent parasitaemia on Day 28. The blood CQ plus DCQ concentrations of these four patients were all above the minimal effective concentration (> 100 ng/ml).</p> <p>Conclusion</p> <p>Chloroquine-resistant <it>P. vivax </it>parasites are emerging in Debre Zeit, Ethiopia. A multi-centre national survey is needed to better understand the extent of <it>P. vivax </it>resistance to CQ in Ethiopia.</p