Decompression of the common peroneal nerve: experience with 20 consecutive cases

A retrospective review of 20 patients with common peroneal nerve palsy treated with decompression between 1986 and 1997 was undertaken. Subjects were evaluated preoperatively and postoperatively by electromyography, nerve conduction, and clinical measures. The mean interval between the onset of symptoms to surgery (operative delay) was 15.9 months. The mean postoperative follow-up was 32.2 months with a minimum follow-up of 1 year. Decompression was performed at the level of the fibular neck and slightly distally at the tendinous origin of the peroneus longus using a standard approach to release tight fascial structures or scar tissue. External neurolysis was performed using the operating microscope in two cases for which scarring of the nerve was identified intraoperatively. Postoperatively, 19 of 20 patients showed improvement in ankle dorsiflexion as assessed by the Medical Research Council scale. Electromyographic examination was useful in the preoperative evaluation and selection of patients for decompression surgery. In conclusion, decompression even after a 1-year delay may offer benefit and suggest early intervention in patients with a severe lesion.     

Brucella abortus strain RB51 vaccination in elk. I. Efficacy of reduced dosage

Bovine brucellosis is a serious zoonotic disease affecting some populations of Rocky Mountain elk (Cervus elaphus nelsoni) and bison (Bison bison) in the Greater Yellowstone Area, USA. The fear that elk and/or bison may spread Brucella abortus to livestock has prompted efforts to reduce or eliminate the disease in wildlife. Brucella abortus strain RB51 (RB51) vaccine has recently been approved for use in cattle. Unlike strain 19 vaccine, RB51 does not cause false positive reactions on standard brucellosis serologic tests. If effective, it may become the vaccine of choice for wildlife. In February 1995, 45 serologically negative female elk calves were trapped and taken to the Sybille Wildlife Research and Conservation Education Unit near Wheatland, Wyoming, USA. In May 1995, 16 of these elk calves were hand-vaccinated with 1 x 10(9) colony forming units (CFU) of RB51, 16 were vaccinated with 1 x 10(8) CFU RB51 by biobullet, and 13 were given a saline placebo. The elk were bred in fall of 1996 and they were challenged with 1 x 10(7) CFU of B. abortus strain 2308 by intraconjunctival inoculation in March 1997. Thirteen (100%) control elk aborted, 14 (88%) hand-vaccinated elk aborted, and 12 (75%) biobullet vaccinated elk aborted or produced nonviable calves. These results suggest that a single dose of 1 x 10(8) to 1 x 10(9) CFU RB51 does not provide significant protection against B. abortus induced abortion in elk. However, the vaccine appears to be safe at this dose and additional study may reveal a more effective RB51 vaccine regimen for elk.     

Molecular constituents of the node of Ranvier

The interaction between neurons and glial cells that results in myelin formation represents one of the most remarkable intercellular events in development. This is especially evident at the primary functional site within this structure, the node of Ranvier. Recent experiments have revealed a surprising level of complexity within this zone, with several components, including ion channels, sequestered with a very high degree of precision and sharply demarcated borders. We discuss the current state of knowledge of the cellular and molecular mechanisms responsible for the formation and maintenance of the node. In normal axons, Na⁺ channels are present at high density within the nodal gap, and voltage-dependent K⁺ channels are sequestered on the internodal side of the paranode—a region known as the juxtaparanode. Modifying the expression of certain surface adhesion molecules that have been recently identified, markedly alters this pattern. There is a special emphasis on contactin, a protein with multiple roles in the nervous system. In central nervous system (CNS) myelinated fibers, contactin is localized within both the nodal gap and paranodes, and appears to have unique functions in each zone. New experiments on contactin-null mutant mice help to define these mechanisms.     

Growth of <Emphasis Type="Italic">Helicobacter pylori</Emphasis> in a long spiral form does not alter expression of immunodominant proteins

Background  

We have previously reported that altered culture conditions (a broth media with shaking) could induce a strain of Helicobacter pylori to assume a long spiral morphology resembling that described for Helicobacter heilmannii. The present study was initiated to determine if other strains of H. pylori could be induced to assume that morphology and if doing so would alter the expression of immunodominant proteins.     

Mad2 and BubR1 function in a single checkpoint pathway that responds to a loss of tension

The spindle checkpoint monitors microtubule attachment and tension at kinetochores to ensure proper chromosome segregation. Previously, PtK1 cells in hypothermic conditions (23 degrees C) were shown to have a pronounced mitotic delay, despite having normal numbers of kinetochore microtubules. At 23 degrees C, we found that PtK1 cells remained in metaphase for an average of 101 min, compared with 21 min for cells at 37 degrees C. The metaphase delay at 23 degrees C was abrogated by injection of Mad2 inhibitors, showing that Mad2 and the spindle checkpoint were responsible for the prolonged metaphase. Live cell imaging showed that kinetochore Mad2 became undetectable soon after chromosome congression. Measurements of the stretch between sister kinetochores at metaphase found a 24% decrease in tension at 23 degrees C, and metaphase kinetochores at 23 degrees C exhibited higher levels of 3F3/2, Bub1, and BubR1 compared with 37 degrees C. Microinjection of anti-BubR1 antibody abolished the metaphase delay at 23 degrees C, indicating that the higher kinetochore levels of BubR1 may contribute to the delay. Disrupting both Mad2 and BubR1 function induced anaphase with the same timing as single inhibitions, suggesting that these checkpoint genes function in the same pathway. We conclude that reduced tension at kinetochores with a full complement of kinetochore microtubules induces a checkpoint dependent metaphase delay associated with elevated amounts of kinetochore 3F3/2, Bub1, and BubR1 labeling.     

Evidence for a founder effect for pseudoxanthoma elasticum in the Afrikaner population of South Africa

Pseudoxanthoma elasticum (PXE) is a heritable elastic tissue disorder recently shown to be attributable to mutations in the ABCC6 ( MRP6) gene. Whereas PXE has been identified in all ethnic groups studied to date, the prevalence of this disease in various populations is uncertain, although often assumed to be similar. A notable exception however is the prevalence of PXE among South African Afrikaners. A previous report has suggested that a founder effect may explain the higher prevalence of PXE in Afrikaners, a European-derived population that first settled in South Africa in the 17th century. To investigate this hypothesis, we performed haplotype and mutational analysis of DNA from 24 South African families of Afrikaner, British and Indian descent. Among the 17 Afrikaner families studied, three common haplotypes and six different disease-causing variants were identified. Three of these mutant alleles were missense variants, two were nonsense mutations and one was a single base-pair insertion. The most common variant accounted for 53% of the PXE alleles, whereas other mutant alleles appeared at lower frequencies ranging from 3% to 12%. Haplotype analysis of the Afrikaner families showed that the three most frequent mutations were identical-by-descent, indicating a founder origin of PXE in this population.     

Lycopene increases urokinase receptor and fails to inhibit growth or connexin expression in a metastatically passaged prostate cancer cell line: a brief communication

The carotenoid lycopene, found in tomatoes, has been associated with decreasing prostate cancer risk. Potential mechanisms for this risk reduction include lycopene's status as a potent antioxidant, its inhibitory effect on cell proliferation, and its ability to increase intercellular gap junctional communication. Presently, in the United States, almost 200,000 men are diagnosed with prostate cancer and approximately 30,000 succumb to its metastatic effects. Therefore, novel treatment strategies are needed for patients who currently have the disease, especially those in advanced, i.e., metastatic status. In this study, we sought to determine if lycopene's inhibitory properties on premalignancy could be extended to advanced prostate cancer by assessing effects on a cell line derived through metastatic passage, the PC-3MM2. We report that in this cell line, lycopene has a potentially unwanted effect of upregulating expression of the urokinase plasminogen activator receptor and facilitating invasion while failing to significantly inhibit proliferation or to induce detectable levels of the gap junctional protein connexin 43 expression. Our results indicate that some caution should be taken with regard to use of lycopene to treat potentially advanced and metastatic prostate cancers.     

A polarity complex of mPar-6 and atypical PKC binds,phosphorylates and regulates mammalian Lgl

The evolutionarily conserved proteins Par-6, atypical protein kinase C (aPKC), Cdc42 and Par-3 associate to regulate cell polarity and asymmetric cell division, but the downstream targets of this complex are largely unknown. Here we identify direct physiological interactions between mammalian aPKC, murine Par-6C (mPar-6C) and Mlgl, the mammalian orthologue of the Drosophila melanogaster tumour suppressor Lethal (2) giant larvae. In cultured cell lines and in mouse brain, aPKC, mPar-6C and Mlgl form a multiprotein complex in which Mlgl is targeted for phosphorylation on conserved serine residues. These phosphorylation sites are important for embryonic fibroblasts to polarize correctly in response to wounding and may regulate the ability of Mlgl to direct protein trafficking. Our data provide a direct physical and regulatory link between proteins of distinct polarity complexes, identify Mlgl as a functional substrate for aPKC in cell polarization and indicate that aPKC is directed to cell polarity substrates through a network of protein-protein interactions.