An epidemiological investigation of an outbreak of leptospirosis associated with swimming, Beaufort, Sabah.

From October 13 to October 21, 1999, a total of 46 males, aged 8 to 19 years, were admitted to Beaufort Hospital after swimming in the creek near an oil palm plantation in Kampung (Kg) Kebatu, Beaufort. Thirty (30) presented with symptoms including fever, vomiting, bodyache, giddiness, headache, chest pain and cough, while 16 others, were asymptomatic. One, a 15 year old boy, died from haemorrhagic shock secondary to pulmonary haemorrhage. The onset of the illness was from 11 October to 19 October 1999. A case-control study found that the outbreak was associated with swimming in the creek (p<0.0001). A total of 44 paired sera samples were sent for microscopic agglutination test (MAT), 5 pairs showed sero-conversion, 3 pairs had 4 fold rise in titre and 18 pairs were positive at >320. The findings indicated that Leptospirosis was the cause of the outbreak of this illness and the contaminated creek water was the source of the infection. The occurrence of flooding and stagnation in the creek following the heavy rainfall during the first week of October 1999 could have contributed to the timing of the outbreak.

Knowledge and attitudes towards tuberculosis among the people living in Kudat District, Sabah.

A multistage random sampling method was used to select the community sample in the district of Kudat, Sabah. A total of 205 respondents from 210 selected houses were interviewed using a standardised questionnaire to ascertain their knowledge and attitude towards tuberculosis. Generally the knowledge about tuberculosis was poor. The well known symptoms that the respondents knew were coughing blood (46.2%), cough (37.1%), loss of weight (34.5%), and loss of appetite (32.0%). Only 51% thought that the disease was caused by germs and it was transmitted by air. TB sufferers were thought to be dirty (22%) and the majority (51%) were not keen to mix with TB patients. Although more than 90% of the respondents considered TB as socially acceptable within their family and community, a large proportion (41%) expressed that getting TB was embarrassing, 4% said it was a disgrace to the family, and 16% said that it was too sensitive to discuss about it. These behaviours suggest that at the private level, the respondents were still perceived negative social attitudes towards tuberculosis.

Src can regulate carboxy terminal interactions with AFAP-110, which influence self-association, cell localization and actin filament integrity.

The SH2 and SH3 binding partner AFAP-110 is a tyrosine phosphorylated substrate of Src. AFAP-110 has been hypothesized to link Src to actin filaments, which may contribute to the effects of Src upon actin filament integrity. However, it has been unclear what effect activated Src (Src527F) has upon AFAP-110 structure or function and whether AFAP-110 plays a role in actin filament integrity. We report here that the carboxy terminal 127 amino acids of AFAP-110 are comprised of an alpha-helical region that contains a leucine zipper motif. This indicated the potential of AFAP-110 to self-associate. Expression of the carboxy terminus as a fusion protein (GST-cterm) will permit affinity absorption of cellular AFAP-110. The integrity of the alpha-helical leucine zipper motif in GST-cterm is required for affinity absorption, but binding is not due to a classical leucine zipper interaction. Co-expression of Src527F, unlike cSrc, will abrogate affinity absorption of AFAP-110 with GST-cterm. These data indicate that Src527F has affected a change in the carboxy terminal structure that renders AFAP-110 unavailable for affinity absorption. Superose chromatography demonstrate that AFAP-110 will fractionate as a monomer or multimer, indicating AFAP-110 can be detected in a self-associated form in cell lysates. Co-expression of Src527F resulted in AFAP-110 fractionating with a molecular weight that predicts only a multimeric population. Deletional mutagenesis also indicate a biological role for the carboxy terminus in cellular localization and actin filament integrity. Deletion of the entire carboxy terminal alpha-helix (84 amino acids) will not permit AFAP-110 to efficiently colocalize with actin filaments or the cell membrane. Deletion of only the leucine zipper region of the carboxy terminal alpha-helix (44 amino acids) from AFAP-110 (AFAPAdeltazip) demonstrate that both AFAPdeltalzip and actin filaments are repositioned into rosette-like structures, similar to the effects of Src527F, while co-expression of AFAP-110 with cSrc will not affect actin filaments. These data indicate that AFAP-110 can play an important role in modulating actin filament integrity through carboxy terminal interactions that can be affected by Src527F.

Structural and functional similarities between the human cytoskeletal protein zyxin and the ActA protein of Listeria monocytogenes.

The intracellular bacterial parasite Listeria monocytogenes produces ActA protein at its surface to facilitate the localized assembly of actin-filled comets that are required for movement. The organization of actin in Listeria comets shows striking similarity to the organization of actin at the plasma membrane of mammalian cells. Therefore we examined the possibility that an ActA-like protein is present in mammalian cells. By using antibodies directed against ActA, we identified zyxin as an ActA related protein in a number of cell types. We compared the functions of ActA and zyxin by transient expression of variants tagged with an inner plasma membrane localization sequence (a CAAX box). Targeting of the proline rich domain of zyxin to the plasma membrane disrupts the actin cytoskeleton and cell shape in a manner similar to that which occurs with membrane-targeted ActA sequences. A chimeric protein composed of the N-terminal domain of ActA fused to the N-terminal and central domains of zyxin induced a full ActA response in cells. Furthermore, zyxin and ActA exhibit common protein partners in vitro. On the basis of the shared properties of zyxin and ActA, we propose that zyxin enhances actin organizing activity in mammalian cells.

AFAP-120. A variant form of the Src SH2/SH3-binding partner AFAP-110 is detected in brain and contains a novel internal sequence which binds to a 67-kDa protein.

SH2 and SH3 domains have been characterized as functional domains that mediate protein-protein interactions in signal transduction. Recently, the cDNA sequence of a novel Src- and Fyn-binding protein called AFAP-110, for Actin-Filament Associated Protein-110 kDa, was reported. This protein was distinctive in that it is both an SH2 and SH3 binding partner for the non-receptor tyrosine kinases Src and Fyn. Here, we report the characterization of an alternatively processed form of AFAP-110 that encodes an additional 258 base pair (bp) of open reading frame. Transient expression of this full-length clone reveals a molecular mass of 120 kDa. Western blot analysis indicate that a larger 120-kDa variant of AFAP-110 can be detected in brain and is not detectable in any other tissues examined. Northern blot analysis indicate that the novel 258-bp insert can be detected in brain RNA but not chick embryo fibroblast RNA. We propose the name AFAP-120, for Actin Filament-Associated Protein-120 kDa. Expression of the 258-bp novel insert (NINS) as a glutathione S-transferase-encoded fusion protein permits adsorption of a 67-kDa protein from tissue lysates. Deletion analysis of the NINS indicates that the interaction with p67 can be attributed to a proline-rich motif that resembles an SH3-binding motif. We hypothesize that AFAP-120 facilitates interactions in brain between SH2/SH3 signaling proteins and actin filaments and that a proline-rich motif in the NINS may exist to facilitate additional interactions between cellular proteins in brain and actin filaments.