The molecular genetics of Bardet-Biedl syndrome.

Bardet-Biedl syndrome (BBS) has been shown to be a genetically heterogeneous disorder involving genes mapping to at least six known loci. One BBS gene (MKKS) has been identified and the form of the disorder caused by this gene is allelic to McKusick-Kaufman syndrome. MKKS codes for a putative chaperonin, suggesting that other BBS genes may also code for components of chaperone complexes or be substrates of chaperone function.

Telomere erosion and senescence in human articular cartilage chondrocytes.

Aging and the degeneration of articular cartilage in osteoarthritis are distinct processes, but a strong association exists between age and the incidence and prevalence of osteoarthritis. We hypothesized that this association is due to in vivo replicative senescence, which causes age-related declines in the ability of chondrocytes to maintain articular cartilage. For this hypothesis to be tested, senescence-associated markers were measured in human articular chondrocytes from donors ranging in age from 1 to 87 years.

Characterization of hepatitis C virus (HCV) and HCV E2 interactions with CD81 and the low-density lipoprotein receptor.

Hepatitis C virus (HCV) or HCV-low-density lipoprotein (LDL) complexes interact with the LDL receptor (LDLr) and the HCV envelope glycoprotein E2 interacts with CD81 in vitro. However, E2 interactions with LDLr and HCV interactions with CD81 have not been clearly described. Using sucrose gradient-purified low-density particles (1.

CD4 and CD8 T cells have redundant but not identical roles in virus-induced demyelination.

A chronic demyelinating disease results from murine infection with the neurotropic strain JHM of mouse hepatitis virus (MHV-JHM). Demyelination is largely immune mediated. In this study, the individual roles of CD4 and CD8 T cells in MHV-induced demyelination were investigated using recombination-activating gene 1-/- (RAG1-/-) mice infected with an attenuated strain of MHV-JHM.

Processing and maturation of flavocytochrome b558 include incorporation of heme as a prerequisite for heterodimer assembly.

The phagocyte NADPH-dependent oxidase generates superoxide by reducing molecular oxygen through a transmembrane heterodimer known as flavocytochrome b(558) (flavocytochrome b). We investigated the biosynthesis of flavocytochrome b subunits gp91(phox) and p22(phox) to elucidate features of flavocytochrome b processing in myeloid cells. Although the gp91(phox) precursor, gp65, was processed to gp91(phox) within 4-8 h of chase, unassembled gp65 and p22(phox) monomers were degraded by the cytosolic proteasome.

Activation of renal mechanosensitive neurons involves bradykinin, protein kinase C, PGE(2), and substance P.

Increased renal pelvic pressure or bradykinin increases afferent renal nerve activity (ARNA) via PGE(2)-induced release of substance P. Protein kinase C (PKC) activation increases ARNA, and PKC inhibition blocks the ARNA response to bradykinin. We now examined whether bradykinin mediates the ARNA response to increased renal pelvic pressure by activating PKC.

Neurotrophin receptors in the somatosensory cortex of the mature rat: co-localization of p75, trk, isoforms and c-neu.

Trk immunoreactivity is expressed by a discrete population of cortical neurons, primarily those with cell bodies in layer Vb and dendrites in supragranular cortex. We tested the hypothesis that neurons co-express multiple isoforms of trk receptors. The distribution of neurons expressing specific high affinity neurotrophin receptors was determined immunohistochemically.

Cyclooxygenase-2 involved in stimulation of renal mechanosensitive neurons.

Stretching of the renal pelvic wall activates renal mechanosensitive neurons, resulting in an increase in afferent renal nerve activity (ARNA). Prostaglandin (PG)E(2) plays a crucial role in the activation of renal mechanosensitive neurons through facilitation of the release of substance P from the sensory neurons in the renal pelvic wall. Because wall stretch may induce cyclooxygenase-2 activity, we examined whether cyclooxygenase-2 was expressed in the renal pelvic wall and whether activation of cyclooxygenase-2 contributed to the ARNA response produced through increased renal pelvic pressure.

Rebirth of granulocyte transfusions: should it involve pediatric oncology and transplant patients?

Several methodologic advances, particularly use of recombinant granulocyte colony stimulating factor to stimulate donors, have made it possible to collect extraordinarily large numbers of normal neutrophils for transfusion into neutropenic patients with life-threatening infections. Because larger doses of neutrophils can be transfused, renewed interest has arisen in the use of neutrophil (granulocyte) transfusions to treat adult oncology patients and progenitor cell transplant recipients, in whom neutropenia complicated by severe infections persists as a significant problem, despite combination antibiotic therapy, recombinant cytokines, myeloid growth factors, and use of mobilized peripheral blood progenitor cells. In this commentary, consideration is given as to whether pediatric oncology and transplant patients might benefit from modern granulocyte transfusion therapy.

CpG-oligodeoxynucleotide-resistant variant of WEHI 231 cells.

Bacterial DNA and synthetic single-stranded oligonucleotides having unmethylated CpG motifs (CpG-ODN) powerfully stimulate cellular immune responses by an unknown mechanism. There is evidence that internalization of the nucleotide is required for activity. Both CpG-ODN and engagement of CD40 protects WEHI-231 murine B lymphoma cells from apoptosis induced by antibody to surface IgM, and both agents induce interleukin-6 (IL-6) production by these cells.

Antagonism of immunostimulatory CpG-oligodeoxynucleotides by 4-aminoquinolines and other weak bases: mechanistic studies.

Oligodeoxynucleotides with unmethylated CpG motifs are immunostimulatory. Chloroquine and a number of structural analogs specifically and powerfully inhibit this effect at nanomolar concentrations. We explored the mechanism of this inhibition, with 4-aminoquinolines, quinacrine, 9-aminoacridines, and novel dibasic analogs, many of which are fluorescent.

Lack of immune stimulation by immobilized CpG-oligodeoxynucleotide.

Selected phosphorothioate oligodeoxynucleotides containing CpG (CpG-ODN) activate immune responses, including B-cell proliferation and cytokine production. The mechanism by which cells detect CpG-motifs is not known. There are conflicting reports in the literature concerning the ability of CpG-ODN linked to solid supports to stimulate immunity.

Despite structural similarities between gp91phox and FRE1, flavocytochrome b558 does not mediate iron uptake by myeloid cells.

Superoxide (O2-) generated by the phagocyte reduced nicotinamide adenine dinucleotide phosphate oxidase is dependent on electron transfer by flavocytochrome b558 (flavocytochrome b), a transmembrane heterodimer that forms the redox center of the oxidase at the plasma or phagosomal membrane. The larger of its two subunits, gp91phox, is homologous to the yeast iron reductase subunit FRE1, and these two proteins share many structural and functional characteristics. Because FRE1 is required for iron uptake in yeast, we hypothesized that flavocytochrome b might serve a similar function in human phagocytes and thus provide a mechanism for the transferrin-independent iron acquisition observed in myeloid cells.

PGE2 increases substance P release from renal pelvic sensory nerves via activation of N-type calcium channels.

Activation of renal pelvic sensory nerves by increased pelvic pressure results in a renal pelvic release of substance P that is dependent on intact prostaglandin synthesis. An isolated renal pelvic wall preparation was used to examine whether PGE2 increases the release of substance P from renal pelvic sensory nerves and by what mechanisms. The validity of the model was tested by examining whether 50 mM KCl increased substance P release from the pelvic wall.

The Pendred syndrome gene encodes a chloride-iodide transport protein.

Pendred syndrome is the most common form of syndromic deafness and characterized by congenital sensorineural hearing loss and goitre. This disorder was mapped to chromosome 7 and the gene causing Pendred syndrome (PDS) was subsequently identified by positional cloning. PDS encodes a putative transmembrane protein designated pendrin.

Amiloride-sensitive Na+ channels in pelvic uroepithelium involved in renal sensory receptor activation.

Stretching the renal pelvic wall increases ipsilateral afferent renal nerve activity (ARNA). This response is enhanced by inhibiting Na+-K+-ATPase with ouabain, suggesting a modulatory role for intracellular Na+ in the activation of mechanosensitive neurons. The messenger RNA for alpha-, beta-, and gamma-subunits of epithelial Na+ channels (ENaC) is found in collecting duct cells.

Attenuation of ischemia-induced activation of cardiac sympathetic afferents following brief myocardial ischemia in cats.

Objective: We have previously shown that brief myocardial ischemia impairs neural conduction in cardiac sympathetic efferent fibers. However, attenuation of the activity of afferent sympathetic nerves, which may contribute to impaired ischemic nociception and reflex hemodynamic responses, is not well understood. Therefore, we studied the electrophysiological effects of brief myocardial ischemia on the mechano-, chemo- and ischemia-sensitive properties of cardiac sympathetic afferent fibers.

Immunolocalization of sat-1 sulfate/oxalate/bicarbonate anion exchanger in the rat kidney.

The rat liver sulfate/bicarbonate/oxalate exchanger (sat-1) transports sulfate across the canalicular membrane in exchange for either bicarbonate or oxalate. Sulfate/oxalate exchange has been detected in the proximal tubule of the kidney, where it is probably involved in the reabsorption of filtered sulfate and the secretion of oxalate and may contribute to oxalate-dependent chloride reabsorption. Screening of a renal cortex cDNA library determined that sat-1 is expressed in the rat kidney.

Role for glucose transporter 1 protein in human breast cancer.

Glycolysis is increased in cancer cells compared with normal cells. It has been shown that glucose enters cells via a family of five functional glucose transporters (GLUT). However, GLUT expression appears to be altered in human breast cancer, which may serve as a selective advantage and facilitate the metastatic potential of these cells.

Posterior ventricular catheter burr-hole localizer. Technical note.

Proper ventricular catheter placements are associated with improved shunt performance. When placing ventricular catheters via the posterior approach, the surgeon must determine an optimum trajectory and then pass a catheter along that trajectory. The incidence of optimal posterior catheter placements is increased by using a posterior catheter guide (PCG); however, errors may still occur because of poor selection of a posterior burr-hole site.

A novel form of hereditary myeloperoxidase deficiency linked to endoplasmic reticulum/proteasome degradation.

Myeloperoxidase (MPO) deficiency is a common inherited disorder linked to increased susceptibility to infection and malignancy. We identified a novel missense mutation in the MPO gene at codon 173 whereby tyrosine is replaced with cysteine (Y173C) that is associated with MPO deficiency and assessed its impact on MPO processing and targeting in transfectants expressing normal or mutant proteins. Although the precursor synthesized by cells expressing the Y173C mutation (MPOY173C) was glycosylated, associated with the molecular chaperones calreticulin and calnexin, and acquired heme, it was neither proteolytically processed to mature MPO subunits nor secreted.

Pattern of inheritance in hereditary myeloperoxidase deficiency associated with the R569W missense mutation.

Myeloperoxidase (MPO) is an essential component of the oxygen-dependent microbicidal system of neutrophils and monocytes. Hereditary deficiency of MPO occurs in 1 in 2,000 to 4,000 individuals in the general population and has been generally considered an autosomal recessive trait. Previous studies have used the peroxidase activity of blood leukocytes to assess the phenotype of affected family members.

Neutrophils exposed to bacterial lipopolysaccharide upregulate NADPH oxidase assembly.

Bacterial LPS is a pluripotent agonist for PMNs. Although it does not activate the NADPH-dependent oxidase directly, LPS renders PMNs more responsive to other stimuli, a phenomenon known as "priming." Since the mechanism of LPS-dependent priming is incompletely understood, we investigated its effects on assembly and activation of the NADPH oxidase.

Long- and short-term variability of automated perimetry results in patients with optic neuritis and healthy subjects.

Objective: To measure the short- and long-term variability of automated perimetry in patients with optic neuritis and normal subjects.

Design: Prospective case-control design of patients with recovered optic neuritis with intraday and interday repetitions to obtain robust variability measurements. Entry criteria included a corrected pattern SD that was worse than the normal 5% probability level and a mean deviation worse than -3 dB but better than -20 dB.