Oral delivery of group A streptococcal cell walls augments circulating TGF-beta and suppresses streptococcal cell wall arthritis.

Oral administration of autoantigens can influence the outcome of experimental autoimmune diseases, yet little is known about nonself Ag-induced tolerance. In this study, we administered group A streptococcal cell wall (SCW) peptidoglycan-polysaccharide complexes orally and monitored the impact on SCW-induced erosive polyarthritis. Oral administration of low dose SCW (3 microg/day), initiated 7 days before an arthritogenic dose of systemic SCW, virtually eliminated the joint swelling and destruction typically observed during both the acute and chronic phases of the arthritis.

The substance P receptor antagonist CP-99,994 reduces acute postoperative pain.

Background: Animal studies suggest that substance P, a peptide that preferentially activates the neurokinin-1 (NK1) receptor, is involved in pain transmission, with particular importance in pain after inflammation.

Methods: The analgesic efficacy of CP-99,994, a NK1 receptor antagonist, was compared with ibuprofen and placebo in 78 subjects undergoing third molar extraction. The initial 60 subjects randomly received 1 of 3 possible treatments in a double-blind fashion before oral surgery: 750 microg/kg CP-99,994 infused intravenously over 5 hours on a tapering regimen starting 2 hours before surgery, 600 mg oral ibuprofen 30 minutes before surgery, or placebo.

New insights into the upregulation and function of the salivary Na+-K+-2Cl- cotransporter.

In many exocrine epithelia, the Na+-K+-2Cl- cotransporter is the main provider of cellular chloride entry during transepithelial salt and water secretion. Because of its accessibility and hormonal responsiveness, the salivary gland has recently emerged as a convenient preparation in which to study the regulation and characteristics of this transport protein. In this review, we summarize recent findings from our laboratory which demonstrate that muscarinic, alpha1-adrenergic and peptidergic stimulation of rat parotid acinar cells induce a dramatic (up to twenty-fold) upregulation of Na+-K+-2Cl- cotransporter activity.

Molecular characterization of the cation-chloride cotransporter family.

Na-K-2Cl cotransporters, Na-Cl cotransporters and K-Cl cotransporters have recently been shown to constitute a new gene family of membrane transport proteins. At least five distinct members of this family of cation-chloride cotransporters have been found in vertebrates and several as yet functionally uncharacterized sequences have been identified in insects, worms and yeast. The relationships among the various known members of this gene family is briefly reviewed along with our current knowledge about the topological structure of these proteins in the plasma membrane.

Preclinical and biological studies using recombinant adenoviruses encoding aquaporins 1 and 5.

In this report, we have reviewed several of our recent studies using replication-deficient recombinant adenoviruses encoding either aquaporin 1 or 5. The aquaporins are a relatively recently described family of water channels that mediate osmotically-driven transmembrane water permeability. Recombinant adenoviruses are highly efficient gene transfer vectors and readily result in significant levels of transgene expression.

In vivo use of adenoviral vectors: effects on salivary gland structure.

Recently there has been considerable progress in the development of in vivo gene transfer technology. By this means, new genetic information may be introduced directly to cells, while the cells remain in their natural milieu. The ability to express exogenous proteins makes it possible to explore the functions of native or altered proteins and thereby develop new insights into cell function and dysfunction.

Integrin signaling: cytoskeletal complexes, MAP kinase activation, and regulation of gene expression.

Members of the integrin family of adhesion receptors mediate interactions of cells with the extracellular matrix. Besides their role in tissue morphogenesis by anchorage of cells to basement membranes and migration along extracellular matrix proteins, integrins are thought to play a key role in mediating the control of gene expression by the extracellular matrix. Studies over the past 10 years have shown that integrin-mediated cell adhesion can trigger signal transduction cascades involving translocation of proteins and protein tyrosine phosphorylation events.

AMPA/kainate antagonist LY293558 reduces capsaicin-evoked hyperalgesia but not pain in normal skin in humans.

Background: Animal studies suggest that alpha-amino-3-hydroxy-5-methyl-4-isoxazole propionic acid-kainate (AMPA-KA) receptors are involved in pain processing. The effects of the competitive AMPA-KA antagonist LY293558 in two types of experimental pain in human volunteers, brief pain sensations in normal skin, and mechanical allodynia-pinprick hyperalgesia were studied after the injection of intradermal capsaicin.

Methods: Brief intravenous infusions of the competitive AMPA-KA antagonist LY293558 were given to 25 healthy volunteers to examine acute toxicity and analgesic effects.

Engagement of cytotoxic T lymphocyte-associated antigen 4 (CTLA-4) induces transforming growth factor beta (TGF-beta) production by murine CD4(+) T cells.

Evidence indicates that cytotoxic T lymphocyte-associated antigen 4 (CTLA-4) may negatively regulate T cell activation, but the basis for the inhibitory effect remains unknown. We report here that cross-linking of CTLA-4 induces transforming growth factor beta (TGF-beta) production by murine CD4(+) T cells. CD4(+) T helper type 1 (Th1), Th2, and Th0 clones all secrete TGF-beta after antibody cross-linking of CTLA-4, indicating that induction of TGF-beta by CTLA-4 signaling represents a ubiquitous feature of murine CD4(+) T cells.

Receptor tyrosine kinase expression in human bone marrow stromal cells.

Bone marrow stromal cells (BMSCs) are a heterogeneous population of cells derived from colony-forming units-fibroblastic (CFU-Fs). These cells reside in the bone marrow cavity and are capable of differentiating into several cell phenotypes including osteoblasts, chondroblasts, hematopoiesis-supporting stromal cells, and adipocytes. However, the factors that regulate the proliferation and differentiation of the BMSC population are for the most part unknown.

Flavopiridol, a novel cyclin-dependent kinase inhibitor, suppresses the growth of head and neck squamous cell carcinomas by inducing apoptosis.

Flavopiridol (HMR 1275) has been identified recently as a novel antineoplastic agent in the primary screen conducted by the Developmental Therapeutics Program, National Cancer Institute. Flavopiridol inhibits most cyclin-dependent kinases (cdks) and displays unique anticancer properties. Here, we investigated whether this compound was effective against head and neck squamous cell carcinomas (HNSCC).

Reducing the burden of oral and pharyngeal cancers.

In the United States, oral and pharyngeal cancers continue to result in significant morbidity and mortality. Dental professionals play a pivotal role in all facets of controlling the burden of oral and pharyngeal cancer-from efforts to prevent its occurrence, to ensuring that oral cancers are detected at the earliest possible stage, to treating these cancers, and to ensuring maximum quality of life and function for oral and pharyngeal cancer survivors. Individually and by making linkages within the community and beyond, dentists can help patients modify their risk of these cancers and can take steps to screen for them, thereby potentially improving survival and function of those who develop oral cancer.

NIDR: 50 years of scientific progress.

The National Institute of Dental Research turns 50 this month. During those 50 years, scientific research has resulted in amazing progress in reducing the prevalence and severity of tooth decay, periodontal diseases, and tooth loss. With these successes in mind, NIDR looks to more progress in such areas as the design and fabrication of biomaterials for replacement of teeth, early detection of caries lesions, and innovative remineralization strategies to optimize and preserve the health of dental tissues.

Mutations in the activation loop tyrosines of protein tyrosine kinase Syk abrogate intracellular signaling but not kinase activity.

The protein tyrosine kinase Syk plays a pivotal role in mediating the high-affinity IgE receptor (Fc epsilonRI)-induced degranulation of mast cells. To examine the mechanism of Syk regulation, the two tyrosine residues at 519 and 520 in the putative activation loop of rat Syk were mutated to phenylalanine either singly or in combination. The various mutants were expressed in a Syk-negative variant of the RBL-2H3 (rat basophilic leukemia 2H3) mast cell line.

Glycosylation and NH2-terminal domain mutants of the tissue inhibitor of metalloproteinases-1 (TIMP-1).

Mutants in the tissue inhibitor of metalloproteinases-1 (TIMP-1) protein have been created by site-directed mutagenesis and expressed in HeLa cells, using a recombinant vaccinia virus system. Removal of either or both glycosylation sites yielded proteins which retained wild-type inhibitory activity against both human fibroblast-type collagenase (FIB-CL) and Mr 72000 gelatinase (GL). However, the double glycosylation mutant protein was expressed at a level that was 2-4-fold lower than that of the wild-type or the single site glycosylation mutants.

Mycobacterium avium complex augments macrophage HIV-1 production and increases CCR5 expression.

Infection with HIV-1 results in pronounced immune suppression and susceptibility to opportunistic infections (OI). Reciprocally, OI augment HIV-1 replication. As we have shown for Mycobacterium avium complex (MAC) and Pneumocystis carinii, macrophages infected with opportunistic pathogens and within lymphoid tissues containing OI, exhibit striking levels of viral replication.

Sensory changes in the territory of the lingual and inferior alveolar nerves following lower third molar extraction.

Post-injury inflammation activates nociceptive systems and recruits normally non-nociceptive afferents into a pain processing role. During inflammation, Abeta low threshold mechanoreceptor afferents that usually mediate tactile sensation acquire properties of nociceptors, allowing them to participate in post-injury spontaneous pain and evoked abnormalities such as tenderness and pain to light touch. This study assessed the sensory consequences of post-injury inflammation following extraction of a single, lower third molar tooth.

Gamma-irradiation-induced cell cycle arrest and cell death in a human submandibular gland cell line: effect of E2F1 expression.

This study examined the effect of gamma-irradiation (5 and 10 Gy) on the human submandibular cell line (HSG). Radiation treatment (5 Gy and 10 Gy) induced a dose-dependent decrease in cell proliferation, with a G2/M arrest of the cell cycle, and an increase in cell death (cells with <2n DNA increased from 7% in control cells to 34% and 40% in 5 and 10 Gy irradiated cells, respectively). [Ca2+]i measurements demonstrated that the status of internal Ca2+ stores, and muscarinic receptor-mediated Ca2+ mobilization, in irradiated cells was comparable to that in non-irradiated cells.

Roles of aggrecan, a large chondroitin sulfate proteoglycan, in cartilage structure and function.

Aggrecan, a large aggregating proteoglycan, is one of the major structural components of cartilage. Its core protein contains three glubular domains and two glycosaminoglycan-attachment domains. These domains play various roles to maintain cartilage structure and function.

Effector domain mutants of Rho dissociate cytoskeletal changes from nuclear signaling and cellular transformation.

The small GTP-binding Rho proteins control a variety of biological activities, including organization of the actin cytoskeleton, regulation of gene expression and cellular transformation. In contrast, Ras proteins do not induce actin stress fibers, but potently transform cells which exhibit a morphology clearly distinct from that caused by activated forms of Rho. To investigate whether nuclear signaling and oncogenic potential of Rho are a consequence of its profound effect on cytoskeletal organization, we replaced each amino acid in the Rho effector loop with those of Ras, or replaced conserved residues with others known to result in differential signaling capability when introduced into Ras and Rac1.

Modulation of cell-cell adherens junctions by surface clustering of the N-cadherin cytoplasmic tail.

Cadherins mediate the formation of cell-cell adherens junctions (AJ) by homophilic interactions through their extracellular domains as well as by interacting with the actin cytoskeleton via their cytoplasmic portions. Cadherin clustering initiates cytoplasmic signaling that results in the assembly of structural components into cell-cell AJ. To elucidate the function of the cytoplasmic tail of cadherins in initiating the assembly signal, we generated and characterized a chimeric cadherin tail fused to an inert transmembrane anchor.