Cyclospora cayetanensis infection in Lagos, Nigeria

Although reports of Cyclospora infection continue to increase globally, few cases have been reported from the African continent. We present 11 cases of cyclosporiasis detected from stool samples submitted to seven major hospital laboratories in Lagos, Nigeria between March 1999 and April 2000.     

Parathyroid hormone related protein in hypercalcaemia of Hodgkin''s disease.

The role of parathyroid hormone related protein (PTHRP) as a humoral mediator of hypercalcaemia was investigated in a patient with lymphocyte depleted Hodgkin's disease during an episode of hypercalcaemia, using an immunohistochemical staining technique for PTHRP on the tumour tissue and an immunoradiometric (IRMA) assay for PTHRP1-86 on the patient's plasma. The plasma PTHRP was less than 0.23 pmol/l in the range found in normocalcaemic controls, and the immunohistochemical staining was not positive for protein. PTHRP did not have a role in the pathogenesis of hypercalcaemia in this patient.     

Increase of glycocalyx and altered lectin agglutination profiles of Pasteurella haemolytica A1 after incubation in bovine subcutaneous tissue chambers in vivo or in ruminant serum in vitro.

Pasteurella haemolytica serotype A1 (bovine strain OK) was incubated for 2 and 6 h in bovine subcutaneous tissue chambers in vivo, and ovine strain 82-25 and bovine strain L011 were incubated in vitro for 2 h in heat-inactivated ovine or bovine serum from which gamma globulin had been depleted by protein G affinity chromatography to assess changes in morphology and lectin agglutination profiles (strains 82-25 and L101 only). Cells, removed from chambers after 2 h, were covered with an extensive, dense glycocalyx extending approximately 0.5 microm from the cell surface. In many cells, the glycocalyx was separated from the cell surface by a clear, electron-transparent area. Cells, removed at 6 h, were covered with a sparse glycocalyx of fine fibers 0.2 to 0.3 microm from the cell surface. Strains 82-25 and L101, incubated for 2 h in heat-inactivated ovine or bovine serum or in heat-inactivated ovine or bovine serum depleted of gamma globulin by protein G affinity chromatography, were also covered with a glycocalyx. The glycocalyx did not bind protein A-colloidal gold and therefore did not contain aggregates of accumulated antibody. Strains 82-25 and L101 were incubated individually for 2 h in 10 mM sodium phosphate buffer (pH 7.2) containing 0.14 M NaCl, 0.5 mM CaCl2, and 0.15 mM MgCl2 or with this buffer and either 25% heat-inactivated, gamma globulin-depleted ovine serum or 25% heat-inactivated, gamma globulin-depleted bovine serum. Agglutination profiles were then determined with 17 lectins in 10 mM HEPES-buffered saline (pH 8.4) with 0.1 mM CaCl2 and 0.08% sodium azide. Profiles did not vary with 10 of 17 lectins. However, profiles did vary with peanut agglutinin, Phaseolus vulgaris leucoagglutinin, Sophora japonica agglutinin, Maackia amurensis lectin II, Narcissus pseudonarcissus (daffodil) lectin, Griffonia simplicifolia lectin I, and Pisum sativum agglutinin. Altered profiles indicate a change in the bacterial cell surface, possibly by adsorption or alteration of surface carbohydrate moieties by serum constituents.     

Multiple sets of visual cortical neurons projecting transitorily through the corpus callosum

In areas 17 and 18 of adult cats only a few neurons send bifurcating axons to more than one contralateral area or to areas in both hemispheres; most neurons seem to project to only one area. We now found that such a selective connectivity is already present at birth, i.e. several weeks before transitory callosal axons are eliminated. This is true even for those portions of cortex which will lose access to the corpus callosum: in particular different neurons project transitorily from medial area 17 to different contralateral areas. Thus cortical neurons may be induced to project to specific targets by a mechanism operating long before (and possibly independent of) the axon elimination. The latter may, however, be responsible for the final topographic organization of the connections.     

Pasteurella haemolytica Leukotoxin-Induced Increase in Phospholipase A2 Activity in Bovine Neutrophils

Exposure of bovine neutrophils to Pasteurella haemolytica leukotoxin (LKT) stimulates the production of leukotriene B₄ (LTB₄), which is believed to be an important chemotactic agent in the development of acute fibrinopurulent pneumonic infection in cattle. The involvement of phospholipase A₂ (PLA₂) in LKT-induced synthesis of LTB₄ was studied by using bovine neutrophils labeled with ³H-arachidonate ([³H]AA). Incubation of isolated neutrophils with [³H]AA resulted in incorporation of radioactivity in the PLA₂ substrates phosphatidylcholine, phosphatidylinositol, and phosphatidylethanolamine. Exposure of radiolabeled neutrophils to LKT caused concentration- and time-dependent release of radioactivity and redistribution of radioactivity in neutrophil membranes consistent with utilization of phosphoglyceride substrate and release of free fatty acid and eicosanoid products. These LKT-induced effects could be inhibited by pretreatment with arachidonyl trifluoromethyl ketone, an inhibitor of type IV cytoplasmic PLA₂, and were dependent on extracellular calcium. These results support the conclusion that LKT-induced synthesis of LTB₄ involves a calcium-mediated increase in PLA₂ activity.     

Identification of Neisseria meningitidis serogroups Y and W135 by siaD nucleotide sequence analysis

Rapid serogrouping of meningococci is essential for the effective public health management of cases of the disease and the contacts of infected patients. Here we describe an accurate nucleotide-sequencing method for the confirmation of serogroup Y and W135 meningococci by siaD gene analysis from cultures of Neisseria meningitidis.     

Comparison of commercial DNA extraction kits for extraction of bacterial genomic DNA from whole-blood samples

The demand for molecular diagnostic tests in medical microbiology has highlighted the need for efficient methods of DNA extraction. In addition, it is preferable for these methods to be automated. An example of such a requirement is for the confirmation of meningococcal disease where rapid, sensitive, and specific procedures are required for public health management purposes. Previous studies have shown that whole blood is the preferred method for the isolation of bacterial DNA in meningococcal disease, and in this study, we compare five commercially available kits for the extraction of bacterial genomic DNA from whole-blood samples. These include kits in a 96-well binding plate, 96-well filter plate, and metallic bead formats. The method for all five kits is described, and the sensitivity, specificity, ease of automation, and overall efficiency are determined.