Isolation of pure sheaths of Litomosoides carinii microfilariae

A method is described for the isolation of pure, chemically intact sheaths of blood microfilariae of Litomosoides carinii. Microfilariae were isolated according to standard techniques. Exsheathment was performed by freezing-thawingshaking procedures, repeated 5–10 times, i.e., larvae were frozen in liquid nitrogen, thawed at room temperature, and shaken vigorously for 5 s. Exsheathment rates were about 50%. Sheaths were separated from ensheathed and exsheathed microfilariae and microfilariae fragments by filtration through a polycarbonate filter (2 m pore size). The achievable yield (about 15% of the sheaths of a batch of microfilariae) was approximately 1 g of sheaths per 10⁶ microfilariae.Supported by the Deutsche Forschungsgemeinschaft     

Recurrence of atrial tachyarrhythmias in implantable cardioverter-defibrillator recipients

BACKGROUND: Because the natural history of atrial tachyarrhythmia (AT) is not known in patients with implantable cardioverter-defibrillators (ICDs) but without device-based atrial therapies, we aimed to describe the characteristics and recurrence of AT in such patients. METHODS: In this multicenter trial, 269 patients with standard indications for ICD placement and 2 episodes of AT in the preceding year received a dual-chamber ICD capable of logging AT. Patients were randomly assigned to 3-month periods of atrial therapies "on" or "off." This analysis considered only the 118 patients with atrial therapies programmed off at ICD placement. RESULTS: Fifty-eight patients (49%) had at least 1 AT episode longer than 1 minute, and 21 (18%) had at least 1 prolonged episode (>24 hours). The median episode frequency for each patient (episodes per month) was 1.8 episodes longer than 1 minute, 0.8 longer than 1 hour, and 0 longer than 24 hours. The median AT burden was 12.2 hours per month. CONCLUSIONS: Patients with standard ICD indications and history of AT have infrequent episodes, frequent short episodes, or prolonged episodes of AT-atrial fibrillation. However, the clinical characteristics examined did not distinguish among the groups. Improved diagnostic tools may help identify patients at risk for development of AT, thereby allowing specific therapies to be targeted to each group of patients.     

The BDNF-Val66Met polymorphism: implications for susceptibility to multiple sclerosis and severity of disease

Neurodegeneration following inflammatory injury is considered to be a pathological correlate of irreversible disability in patients with multiple sclerosis. The availability of neurotrophins could influence the probability or rate of disease progression and the time of onset. The BDNF-Val66Met-polymorphism leads to altered intracellular transport and secretion of BDNF, and is thus a logical candidate for a gene that influences susceptibility and, more specifically, the clinical course of multiple sclerosis. In order to test this hypothesis we genotyped the polymorphism in 951 UK multiple sclerosis trio families, but found no evidence for association before (p=0.63) or after stratification for clinical course (p=0.73).     

Expression of the protein inhibitor of nitric oxide synthase in the adult rat retina before and after optic nerve lesion

The molecular messenger nitric oxide (NO) not only serves a number of physiologic functions, but is also involved in the pathophysiology of neurodegeneration. It is produced by the nitric oxide synthase (NOS) isoenzymes. One of the many players regulating NOS activity is the Protein Inhibitor of NOS, PIN. To gain further insight into the mechanisms of NOS regulation and NO-mediated cell death after nerve trauma, we examined PIN expression in a standard model of lesion-induced neurodegeneration, the rat optic nerve transsection model. In both the axotomized retinae and the control retinae PIN expression was predominantly observed in the retinal ganglion cell layer. Optic nerve lesion did neither change the amount of PIN mRNA, as determined by in situ hybridization and real-time RT-PCR, nor did it change the amount of PIN as determined by immunohistochemistry and Western blot analysis. These results suggest that in our model, NOS activity is not regulated by altered PIN levels, which contributes to our understanding of apoptotic mechanisms in injured neurons.     

Caspase-1 is not required for type 1 diabetes in the NOD mouse

Interleukin (IL)-1 beta and IL-18 are two cytokines associated with the immunopathogenesis of diabetes in NOD mice. Both of these cytokines are cleaved by caspase-1 to their biologically active forms. IL-1 is a proinflammatory cytokine linked to beta-cell damage, and IL-18 stimulates production of interferon (IFN)gamma in synergy with IL-12. To examine the effects produced by caspase-1 deficiency on diabetes development in NOD/Lt mice, a disrupted Casp1 gene was introduced by a speed congenic technique. Casp1(-/-) bone marrow-derived macrophages stimulated with lipopolysaccharide produced no detectable IL-18, fourfold lower IL-1 beta, and 20-30% less IL-1 alpha than macrophages from wild-type Casp1(+/+) or Casp1(+/-) controls. Unexpectedly, despite reduced IL-1 and IL-18, there was no change in the rate of diabetes or in total incidence as compared with that in wild-type NOD mice. IL-1 reportedly makes an important pathological contribution in the multidose streptozotocin model of diabetes; however, there was no difference in sensitivity to streptozotocin between NOD mice and NOD.Casp1(-/-) mice at 40 mg/kg body wt or at 25 mg/kg body wt dosage levels. These findings show that caspase-1 processing of IL-1 beta and IL-18 is not absolutely required for mediation of spontaneous or chemically induced diabetes pathogenesis in the NOD mouse.     

Neoexpression of N-cadherin in E-cadherin positive colon cancers

In our study, we aimed to investigate the expression of N-cadherin and E-cadherin and their dependency on epithelial-mesenchymal transition regulators SNAI1, SIP1 and TWIST in human colon cancer. Expression of E-cadherin and N-cadherin was examined by immunohistochemistry in 80 colon carcinomas by using paraffin embedded and formalin fixed tissues. Those cases were partly analyzed for mRNA expression of N-cadherin (42 cases), TWIST (18 cases), SNAI1 (25 cases) and SIP1 (25 cases) by real-time quantitative RT-PCR. Additionally, colon carcinomas that showed amplification of 20q13, the localization of the human SNAI1 gene, were examined. We found cytoplasmic and/or membrane-associated immunoreactivity of N-cadherin in 35/80 (44%) of the cases. However, there was no correlation to upregulated TWIST mRNA levels, as we have shown previously for diffuse-type gastric cancers with abnormal N-cadherin expression. Reduced and/or cytoplasmic E-cadherin immunoreactivity was detected in 19% (15/80) of the cases. Expression of SNAI1 or SIP1 mRNA was not seen in any of the 25 cases analyzed. There was no correlation between amplification of 20q13 and SNAI1 mRNA expression. Remarkably, N-cadherin was almost exclusively expressed in those cases showing normal E-cadherin immunoreactivity, suggesting a mutual exclusion between abnormal E-cadherin reduction and upregulation of N-cadherin. For the first time, we postulate a role for N-cadherin in primary colon cancer progression, which may be similar to the effect discovered by others in breast cancer cell lines, where coexpressed N-cadherin can exert a dominant function over E-cadherin's adhesive function and thus promote tumor invasiveness.     

Book Review

BOOK REVIEW

Book Review