Brachyspira species and gastroenteritis in humans.

Brachyspira species have been implicated as a potential cause of gastroenteritis in humans; this is, however, controversial. In 733 gastroenteritis cases and 464 controls, we found 29 samples positive for Brachyspira species (2.3% of cases and 2.6% of controls; P = 0.77). Brachyspira species were not associated with gastroenteritis in humans.

Spontaneous cure of American cutaneous leishmaniasis due to Leishmania naiffi in two Dutch infantry soldiers.

We report two Dutch infantry soldiers who acquired American cutaneous leishmaniasis (ACL) during military jungle training in Surinam. The lesions had existed for 3 and 5 months, respectively, before the soldiers presented for treatment. The lesions occurred on the head and right thigh, and were small, uncomplicated and symptomless. PCR for Leishmania revealed Leishmania naiffi in both patients. No treatment was given, and the lesions in both men healed spontaneously within 4 and 6 weeks, respectively, after presentation to our clinic. CL is one of the important 'tropical' diseases in The Netherlands, primarily due to the increasing numbers of cases in travellers and in military personnel serving overseas. ACL due to L. naiffi is thought to be a mild expression of CL with a self-limiting nature. Lesions seem to be single, mostly small, ulcerating and usually appear on the hands, arms and legs. No case of mucocutaneous leishmaniasis has yet been attributed to this parasite.

Detection and identification of Toxocara canis DNA in bronchoalveolar lavage of infected mice using a novel real-time PCR.

Toxocarosis is a zoonosis with worldwide distribution caused by Toxocara spp. of dogs and cats. In humans, diagnosis relies mainly on detection of parasite-specific antibodies. Although serological assays in current use have defined sensitivity and specificity, the problem of cross-reactivity still remains, particularly in areas of endemic polyparasitism. Microscopic detection of the parasite in tissue biopsies is not recommended for diagnosis because larvae can be difficult to locate, and finding the parasite eggs in faeces is not applicable since the larvae do not develop to the adult stage in the human host. In this study we describe a novel real-time PCR ('Nemo-PCR') that, in combination with DNA sequencing, allows the detection and identification of Toxocara canis and other nematodes in the Superfamily Ascaridoidea. Results indicate that this approach can detect Toxocara spp. DNA in bronchoalveolar lavage (BAL) of experimentally-infected mice. For diagnostic purposes further studies are necessary to evaluate this assay including testing human BAL fluid. The availability of such a direct assay would improve diagnosis of toxocarosis particularly for patients with pulmonary signs and symptoms.

Detection of translation terminating mutations in the PKD1 gene.

Since the identification of the PKD1 gene in 1994, few mutations have been found. This is mainly due to the very strong homology between a large part of the PKD1 gene and another locus on the short arm of chromosome 16. It is expected that the majority of mutations at the PKD1 locus will be small deletions, insertions and point mutations. Amplification of a piece of DNA derived from the repeated area of the PKD1 gene will result in co-amplification of DNA fragments from the other locus. Detection of mutations is significantly hampered this way. We present a procedure, using the protein truncation test, which reduces the complexity caused by the homologous sequences. We have studied a group of 20 patients with ADPKD at the 3' end of the PKD1 transcript and have produced promising results.

Cytoplasmic acidification facilitates but does not mediate DIF-induced prestalk gene expression in Dictyostelium discoideum.

Stalk cell differentiation in Dictyostelium can be induced by the differentiation-inducing factor, DIF, or by conditions that decrease intracellular pH (pHi). We have investigated whether cytoplasmic acidification acts directly to induce expression of pDd56 and pDd63, two DIF-regulated genes, specifically expressed in prestalk cells. The weak base methylamine, which increases pHi, inhibits DIF-induced transcription. The weak acid 5,5-dimethyl-2,4-oxazolidinedione (DMO), which decreases pHi, stimulates DIF-induction of the two prestalk genes. After relatively long incubation periods, DMO also induces a low level of prestalk gene expression in the absence of added DIF. However, unlike DIF-mediated induction, the apparent DMO-mediated induction decreases to undetectable levels when the cell density is reduced from 10(7) to 10(5) cells/ml. This indicates that DMO does not itself induce gene expression, but acts to enhance the effects of an autonomously secreted stalk-inducing factor, presumably DIF. These results suggest that the effects of DIF on gene expression are regulated by intracellular pH, but do not support a role for protons as direct intermediates in the DIF signal transduction pathway.

Mutation detection in the repeated part of the PKD1 gene.

The principle cause of one of the most prevalent genetic disorders, autosomal dominant polycystic kidney disease, involves mutations in the PKD1 gene. However, since its identification in 1994, only 27 mutations have been published. Detection of mutations has been complicated because the greater part of the gene lies within a genomic region that is reiterated several times at another locus on chromosome 16. Amplification of DNA fragments in the repeated part of the PKD1 gene will lead to coamplification of highly homologous fragments derived from this other locus. These additional fragments severely hamper point-mutation detection. None of the point mutations published to date are located in the repeated part of the PKD1 gene. However, we have reduced the problems posed by the strong homology, by using the protein-truncation test, and we have identified eight novel mutations, seven of which are located in the repeated part of the PKD1 gene.