Evaluation of habitat management strategies for the reduction of malaria vectors in northern Belize.

Mowing and burning of emergent vegetation were evaluated as potential management strategies for the control of the malaria vector, Anopheles vestitipennis, in northern Belize, Central America. The primary aim was reduction of tall dense macrophytes (dominated by Typha domingensis) as preferred larval habitat for An. vestitipennis. Nine experimental plots were established in a Typha marsh in Orange Walk District, Belize. Three plots were burned, three were treated by subaquatic mowing, and three were unaltered controls. After treatment, Typha height was most dramatically affected by the mow treatment. Plant heights at 21 and 95 days post-treatment reflected an 89% and 48% decrease, respectively, compared to pretreatment conditions. The Typha height in the burn plots was not as severely affected. Heights at 21 days post-treatment were 39% lower than those of pre-treatment vegetation, with a return to near pre-test heights by 95 days post-treatment. Both treatments resulted in a significant reduction in the number of An. vestitipennis larvae collected as compared to control plots. Conversely, the treatments resulted in increased larval densities of several other vector and pest mosquito species. Larval population densities ofAn. albimanus, Ochlerotatus taeniorhynchus, and Culex coronator were significantly higher in burn plots. In mow plots, there were significant increases in An. albimanus and Oc. taeniorhynchus larval populations. Non-target invertebrate species affected by the treatments were adult Tropisternus collaris, larval Corythrella, and adult Parapleapuella.     

Complement mediates the binding of HIV to erythrocytes

A fraction of HIV is associated with erythrocytes even when the virus becomes undetectable in plasma under antiretroviral therapy. The aim of the present work was to further characterize this association in vitro. We developed an in vitro model to study the factors involved in the adherence of HIV-1 to erythrocytes. Radiolabeled HIV-1 (HIV) and preformed HIV-1/anti-HIV immune complexes (HIV-IC) were opsonized in various human sera, purified using sucrose density gradient ultracentrifugation, and incubated with human erythrocytes. We observed that, when opsonized in normal human serum, not only HIV-IC, but also HIV, bound to erythrocytes, although the adherence of HIV was lower than that of HIV-IC. The adherence was abolished when the complement system was blocked, but was maintained in hypogammaglobulinemic sera. Complement-deficient sera indicated that both pathways of complement were important for optimal adherence. No adherence was seen in C1q-deficient serum, and the adherence of HIV was reduced when the alternative pathway was blocked using anti-factor D Abs. The adherence could be inhibited by an mAb against complement receptor 1. At supraphysiological concentrations, purified C1q mediated the binding of a small fraction of HIV and HIV-IC to erythrocytes. In conclusion, HIV-IC bound to erythrocytes as other types of IC do when exposed to complement. Of particular interest was that HIV alone bound also to erythrocytes in a complement/complement receptor 1-dependent manner. Thus, erythrocytes may not only deliver HIV-IC to organs susceptible to infection, but free HIV as well. This may play a crucial role in the progression of the primary infection.     

Nutritional regulation of adipose tissue lipoprotein lipase is blunted in insulin resistant rats

Background  

Hypertriglyceridemia is a common lipid abnormality accompanying insulin resistance. This study was designed to assess the contribution of dysregulation of adipose tissue lipoprotein lipase (LPL) activity to the hypertriglyceridemia in a rat model of insulin resistance.     

ATP binding site on the C-terminus of the vanilloid receptor

Transient receptor potential channel vanilloid receptor subunit 1 (TRPV1) is a thermosensitive cation channel activated by noxious heat as well as a wide range of chemical stimuli. Although ATP by itself does not directly activate TRPV1, it was shown that intracellular ATP increases its activity by directly interacting with the Walker A motif residing on the C-terminus of TRPV1. In order to identify the amino acid residues that are essential for the binding of ATP to the TRPV1 channel, we performed the following point mutations of the Walker A motif: P732A, D733A, G734A, K735A, D736A, and D737A. Employing bulk fluorescence measurements, namely a TNP-ATP competition assay and FITC labelling and quenching experiments, we identified the key role of the K735 residue in the binding of the nucleotide. Experimental data was interpreted according to our molecular modelling simulations.     

Atypical localization of myenteric ganglia in the human appendical wall: a comparative study with animal appendix

The presence of well developed appendices in some animals when compared to humans has led to speculation that appendix is a vestigial organ. Increasing number of studies have revealed that the appendix serves as an important organ in humans. The function of animal appendix, and the differences between species remain poorly understood. In this study we examined human myenteric plexus and compared them with animal studies. Appendices were obtained from five young adults in which the appendix was found to be normal after removal. Fixed appendix cryosections were examined by immunofluorescence methods using neuronal marker antibodies to neurofilaments and beta III tubulin. Both antibodies stained myenteric ganglia which were arranged in an apparently irregular pattern in human appendix wall. We observed unexpected localization of myenteric ganglia in the subserosa often accompanied by rarely occurring ganglia in the longitudinal muscle layer. These ganglia were of different sizes and shapes and unequally distributed under a thin layer of serosa. Our findings raise many questions about the possible role of irregular and atypical myenteric ganglia localization in relation to altered motility and subsequent pathogenesis of the appendix in inflammatory disease in humans. On the other hand, studies of the literature have revealed simplicity in the organization of myenteric plexus, e.g., in well-developed rabbit appendix. In addition, appendicitis in animals is restricted to in apes with similarly shaped appendix to humans.     

Standardisation of restriction fragment length polymorphism analysis for Mycobacterium avium subspecies paratuberculosis.

DNA from 1008 strains of Mycobacterium avium subspecies paratuberculosis, digested by restriction endonucleases PstI and BstEII, was hybridised with a standard IS900 probe prepared by PCR and labelled non-radioactively by ECL. DNA fingerprints were scanned by CCD camera and analysed using the software Gel Compar (Applied Maths, Kortrijk, Belgium). Thirteen restriction fragment length polymorphism (RFLP) (PstI) types were detected, which where designated as A, B, C, D, E, F, G, H, I, J, K, L and M in accordance with the study of Pavlik et al. (1995) [Pavlik, I., Bejckova, L., Pavlas, M., Rozsypalova, V., Koskova, S., 1995. Characterization by restriction endonuclease analysis and DNA hybridization using IS900 of bovine, ovine, caprine and human dependent strains of Mycobacterium paratuberculosis isolated in various localities. Vet. Microbiol. 45, 311-318]. Twenty RFLP (BstEII) types were detected and designated as C1-3, C5, C7-20, S1 and I1 in accordance with the study by Collins et al. 1990 [Collins, D.M., Gabric, D.M., de Lisle, G.W., 1990. Identification of two groups of Mycobacterium paratuberculosis strains by restriction endonuclease analysis and DNA hybridization. J. Clin. Microbiol. 28, 1591-1596]. A combination of both RFLP (PstI) and RFLP (BstEII) results revealed a total of 28 different RFLP types. All the RFLP types and detailed protocols are available at Intemet web site WWW...: http:/ /www.vri.cz/wwwrflptext.htm.