A mutational hot spot in the KCNQ4 gene responsible for autosomal dominant hearing impairment

Several different mutations in the KCNQ4 K+ channel gene are responsible for autosomal dominant nonsyndromic hearing impairment (DFNA2). Here we describe two additional families originating from Europe and Japan with a KCNQ4 missense mutation (W276S) that was previously found in one European family. We compared the disease-associated haplotype of the three W276S-bearing families using closely linked microsatellite markers and intragenic single nucleotide polymorphisms. Differences between the haplotypes were found, excluding a single founder mutation for the families. Therefore, the W276S mutation has occurred three times independently, and most likely represents a hot spot for mutation in the KCNQ4 gene.     

Synectin/syndecan-4 regulate coronary arteriolar growth during development.

Syndecan-4 and its cytoplasmic binding partner, synectin, are known to play a role in FGF-2 signaling and vascular growth. To determine their roles in coronary artery/arteriolar formation and growth, we compared syndecan-4 and synectin null mice with their wild-type counterparts. Image analysis of arterioles visualized by smooth muscle alpha-actin immunostaining revealed that synectin (-/-) mice had lower arteriolar length and volume densities than wild-type mice. As shown by electron microscopic analysis, arterioles from the two did not differ in morphology, including their endothelial cell junctions, and the organization and distribution of smooth muscle. Using micro-computer tomography, we found that the size and branching patterns of coronary arteries (diameters > 50 microm) were similar for the two groups, a finding that indicates that the growth of arteries is not influenced by a loss of synectin. Syndecan-4 null male mice also had lower arteriolar length densities than their gender wild-type controls. However, female syndecan-4 null mice were characterized by higher arteriolar length and volume densities than their gender-matched wild-type controls. Thus, we conclude that both synectin and syndecan-4 play a role in arteriolar development, a finding that is consistent with previous evidence that FGF-2 plays a role in coronary arterial growth. Moreover, our data reveal that gender influences the arteriolar growth response to syndecan-4 but not to synectin.     

Analytical technique for quantification of selected resorbable calcium phosphate bone void fillers with the use of polarized-light microscopy

Synthetic calcium phosphate bone void fillers promote varying rates of bone formation and material resorption depending on chemistry, porosity, pore structure, and implant site. The objective of this study was to quantify the resorption of a novel ultraporous beta-tricalcium phosphate cancellous bone void filler with simultaneous quantification of bone formation in a canine humerus model. Potential measurement error involved in conventional histomorphometry using Von Kossa stains inspired the development of a new technique. This technique utilizes bright-field and polarized-light microscopy in conjunction with image analysis software, allowing more accurate histomorphometry. This technique was validated with two separate controlled experiments. Scanning electron microscopy further supported the results. The findings suggest that the use of polarized-light microscopy combined with image analysis software can be an effective tool in simultaneously quantifying calcium phosphate resorption and bone formation.     

The cytotoxic HLA-DQ3 reactive human hybridoma antibody 4166 that May distinguish DQ7 + 8 from DQ9

The human cytotoxic hybridoma antibody 4166 (IgM_χ) was generated by fusing an in vitro EBV-transformed B-LCL from a multiparous woman with the mouse-human heteromyeloma fusion partner CB-F7. In microcytotoxicity and IIF tests with B-LCLs as target cells, the mAb 4166 was specific for DQ3 ( = DQ7 + 8 + 9). However, when used for DQ typing of class-II-positive PBMCs, 4166 could be rendered functionally specific for DQ7 + 8and did not react with DQ9⁺ PBMCs. Binding of mAb 4166 to DQ8-positive cells was efficiently blocked by several allotype-specific mAbs recognizing DQ8. Other HLA class-II-specific mAbs were unable to inhibit. With the use of mAb 4166, it is possible to discriminate DQ7 + 8 from DQ9 in serologic DQ typing.     

Enzymatic activities induced by interferon in human fibroblast cell lines differing in their sensitivity to the anticellular activity of interferon

IF^r, a subline of transformed human fibroblast cells, which is sensitive to the antiviral but resistant to the anticellular activity of interferon, was found to be equally well inducible as its parental cell line RSa for the two major interferon-mediated double-stranded RNA-dependent enzymatic activities, 2–5A synthetase and 73K phosphoprotein kinase. The induction of 2-5A synthetase as a function of interferon dose, the specific activity of the 2-5A synthetase, the nature of the 2-5A oligonucleotide products, and the activity of the 2-5A-activated endonuclease were essentially the same for both cell lines. The 73K phosphoprotein kinase was induced at a similar rate of activity, whether detected in solution or after immobilization on poly(I)·poly(C)-Sepharose. Our observations thus suggest that the induction of these two enzymatic activities are not sufficient for the anticellular activity of interferon.     

Thirty-year survival with an untreated malignant duodenal somatostatinoma

Gastrointestinal somatostatinomas are rare. Only 56 cases with duodenal origin have been reported in the literature. The long-term course of an untreated tumor like this is unknown. We report a case of a male patient who lived 30 yr with an untreated metastatic duodenal somatostatinoma. This case suggests that a duodenal somatostatinoma may be of low malignant potential and that expectancy when treating this tumor might be indicated.     

Galanin-positive nerves of trigeminal origin innervate rat cerebral vessels

Galanin (GAL)-positive nerve fibers in rat cerebral vessels were demonstrated by immunohistochemistry, and their origin in the trigeminal ganglia and pathway in the nasociliary nerve to the vessels was shown by retrograde tracer technique and nerve transection. Some fibers in the vertebrobasilar system appear to originate in extracranial sources. With the antiserum used only few GAL fibers could be seen in the vessels, mostly in the vertebrobasilar system. In neonatally sympathectomized animals a rich network could be visualized in most pial arteries - still particularly in the vertebrobasilar system - probably as a result of a diminished competition for nerve growth factor. No vasomotor effect of GAL could be detected in isolated segments of pial arteries, neither in normal nor in sympathectomized animals, which rules out a direct postsynaptic effect on vascular tone. GAL did not display prejunctional modulatory action on the adrenergic nerves present in the vascular preparations. A sensory function of GAL is discussed.