Biomedical subjects
Publications and source records attributed to J S Rubin.
Communication disorders represent a major and growing problem worldwide. In Europe, the specialty of phoniatrics has developed partly in response to this important issue. This article reviews training and workforce issues in phoniatrics and raises key questions and issues that need resolution in the future.
Helicobacter pylori is an accepted cause of chronic active gastritis and has a major causative role in peptic ulceration. It is a gastric carcinogen. Its role in non-ulcer dyspepsia (NUD) is less clear; yet 50 per cent of patients with NUD are infected with H pylori. H pylori has been investigated in several other organ systems, but has not been investigated extensively in squamous cell carcinoma of the upper aerodigestive tract, a region which could be directly exposed to the bacterium by gastro-oesophageal reflux (GOR). In this study 61 patients with severe laryngeal dysplasia or frank carcinoma of the head and neck are striated by age, investigated for the presence of antibodies to H pylori and compared to age and sex matched controls. In the age group of 46-61 years, the presence of H pylori antibodies was marginally greater in the experimental (63.0 per cent) than the control group (40.7 per cent) (Pearson Chi square p = 0.055, Fisher 2-sided exact test p = 0.066). When combining this age group with the younger age group and thereby creating two roughly equal groups (n = 31 and n = 30) there was also a statistical trend towards increased positivity in the experimental group. These findings are discussed in the light of other studies with gastro-oesophageal reflux disease (GORD).
Helicobacter pylori (HP) is an accepted cause of chronic active gastritis and has a major causative role in peptic ulcers. It is a gastric carcinogen. Its role in nonulcer dyspepsia (NUD) is less clear, yet 50% of patients with NUD are infected with HP, and some recent literature demonstrates long-term improvement of symptoms following eradication. HP has been investigated in several other organ systems, but has not been investigated to any major degree in laryngeal disorders, a region that could be directly exposed to the bacterium from pharyngolaryngeal reflux. This study represents one arm of a larger study designed to investigate such a relationship. Of 101 patients with nonmalignant voice disorders presenting to our voice clinics, 54.5% tested positive for the H. pylori organism. Of the controls, 47.1% tested positive. When striated into age groups of < 45 years, 46-61 years, and > 62 years, and then age-matched with the controls, the likelihood of infection with the H. pylori organism was greater in both the experimental middle group, and in the middle group when combined with the elder group, than in the matched controls, and this difference demonstrated a trend approaching statistical significance. This finding is discussed in the light of other studies on HP and on gastroesophageal reflex (GER).
Hepatocyte growth factor (HGF) is a secreted, heparan sulfate (HS) glycosaminoglycan-binding protein that stimulates mitogenesis, motogenesis, and morphogenesis in a wide array of cellular targets, including hepatocytes and other epithelial cells, melanocytes, endothelial cells, and hematopoietic cells. NK1 is an alternative HGF isoform that consists of the N-terminal (N) and first kringle (K1) domains of full-length HGF and stimulates all major HGF biological activities. Within NK1, the N domain retains the HS binding properties of full-length HGF and mediates HS-stimulated ligand oligomerization but lacks significant mitogenic or motogenic activity. In contrast, K1 does not bind HS, but it stimulates receptor and mitogen-activated protein kinase activation, mitogenesis, and motogenesis, demonstrating that structurally distinct and dissociable domains of HGF are the primary mediators of HS binding and receptor activation. Despite the absence of HS-K1 binding, K1 mitogenic activity in HS-negative cells is strictly dependent on added soluble heparin, whereas K1-stimulated motility is not. We also found that, like the receptors for fibroblast growth factors, the HGF receptor c-Met binds tightly to HS. These data suggest that HS can facilitate HGF signaling through interaction with c-Met that is independent of HGF-HS interaction and that the recruitment of specific intracellular effectors that mediate distinct HGF responses such as mitogenesis and motility is regulated by HS-c-Met interaction at the cell surface.
Inactivation of glycogen synthase kinase 3beta (GSK3beta) and the resulting stabilization of free beta-catenin are critical steps in the activation of Wnt target genes. While Akt regulates GSK3alpha/beta in the phosphatidylinositide 3-OH kinase signaling pathway, its role in Wnt signaling is unknown. Here we report that expression of Wnt or Dishevelled (Dvl) increased Akt activity. Activated Akt bound to the Axin-GSK3beta complex in the presence of Dvl, phosphorylated GSK3beta and increased free beta-catenin levels. Furthermore, in Wnt-overexpressing PC12 cells, dominant-negative Akt decreased free beta-catenin and derepressed nerve growth factor-induced differentiation. Therefore, Akt acts in association with Dvl as an important regulator of the Wnt signaling pathway.
Wnt-4 signaling plays a critical role in kidney development and is associated with the epithelial conversion of the metanephric mesenchyme. Furthermore, secreted Frizzled-related proteins (sFRPs) that can bind Wnts are normally expressed in the developing metanephros, and function in other systems as modulators of Wnt signaling. sfrp-1 is distributed throughout the medullary and cortical stroma in the metanephros, but is absent from condensed mesenchyme and primitive tubular epithelia of the developing nephron where wnt-4 is highly expressed. In contrast, sfrp-2 is expressed in primitive tubules. To determine their role in kidney development, recombinant sFRP-1, sFRP-2 or combinations of both were applied to cultures of 13-dpc rat metanephroi. Both tubule formation and bud branching were markedly inhibited by sFRP-1, but concurrent sFRP-2 treatment restored some tubular differentiation and bud branching. sFRP-2 itself showed no effect on cultures of metanephroi. In cultures of isolated, induced rat metanephric mesenchymes, sFRP-1 blocked events associated with epithelial conversion (tubulogenesis and expression of lim-1, sfrp-2 and E-cadherin); however, it had no demonstrable effect on early events (compaction of mesenchyme and expression of wt1). As shown herein, sFRP-1 binds Wnt-4 with considerable avidity and inhibits the DNA-binding activity of TCF, an effector of Wnt signaling, while sFRP-2 had no effect on TCF activation. These observations suggest that sFRP-1 and sFRP-2 compete locally to regulate Wnt signaling during renal organogenesis. The antagonistic effect of sFRP-1 may be important either in preventing inappropriate development within differentiated areas of the medulla or in maintaining a population of cortical blastemal cells to facilitate further renal expansion. On the other hand, sFRP-2 might promote tubule formation by permitting Wnt-4 signaling in the presence of sFRP-1.
The metanephric kidney develops from interactions between the epithelial ureteric bud and adjacent metanephric mesenchyme, which is induced by the bud to form the epithelia of the nephron. We have found that leukemia inhibitory factor (LIF) and transforming growth factor beta 2 (TGF beta 2) are secreted by inductive rat bud cells and cooperate to enhance and accelerate renal tubule formation in uninduced rat metanephric mesenchymal explants. LIF alone or TGF beta 2 with fibroblast growth factor 2 induced numerous tubules in isolated mesenchymes over an 8 day period, while (in combination) all three caused abundant tubule formation in 72 hours. Furthermore, neutralization of Wnt ligands with antagonist-secreted Frizzled-related protein 1 abrogated these responses and combinatorial cytokine/growth factor stimulation of explants augmented nuclear activation of Tcf1/Lef1, suggesting that LIF and TGF beta 2/FGF2 cooperate to regulate nephrogenesis through a common Wnt-dependent mechanism.
We have previously shown that pretreatment of mice with keratinocyte growth factor (KGF), an epithelial tissue repair factor, can ameliorate graft-versus-host disease (GVHD) after intensive chemoradiotherapeutic conditioning and allogeneic bone marrow transplantation (BMT). To determine whether this effect was dependent on a KGF-mediated mechanism affecting repair of conditioning-induced epithelial cell injury, we studied GVHD in the absence of conditioning using BALB/c severe combined immune-deficient (SCID) recipients given C57BL/6 T cells. KGF (5 mg/kg per day, subcutaneously) given either before or after T-cell transfer enhanced body weights and extended survival. KGF-treated recipients had elevated serum levels of the Th2 cytokine interleukin 13 (IL-13) on day 6 after T-cell transfer concomitant with reduced levels of the inflammatory cytokines tumor necrosis factor-alpha (TNF-alpha) and interferon gamma (IFN-gamma). A 3-day KGF pretreatment also depressed the secondary in vitro mixed lymphocyte response (MLR) of C57BL/6 splenocytes taken 7 days after in vivo alloimmunization with irradiated BALB/c spleen cells. To determine whether KGF would inhibit host-antidonor-mediated BM rejection, pan-T-cell-depleted BALB/c BM cells were infused into sublethally irradiated C57BL/6 mice and administered KGF either before or before and after BMT. Surprisingly, all KGF schedules tested actually resulted in enhanced alloengraftment. The presence of KGF receptor on donor antihost alloreactive T cells could not be detected by binding studies with radiolabeled KGF, reverse transcriptase-polymerase chain reaction, and Western blotting. Therefore, the mechanism of action of KGF on inhibiting T-cell-mediated immune effects may not be due to a direct effect of KGF on T cells. These studies demonstrate that KGF, by mechanisms independent of repair of conditioning-induced injury, has great potential as an anti-GVHD therapeutic agent with the added benefit of inhibiting the rejection of pan-T-cell-depleted donor BM allografts. (Blood. 2000;96:4350-4356)
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Secreted Frizzled-related protein-1 (sFRP-1) contains a cysteine-rich domain homologous to the putative Wnt-binding site of Frizzleds. To facilitate the biochemical and biological analysis of sFRP-1, we developed a mammalian recombinant expression system that yields approximately 3 mg of purified protein/liter of conditioned medium. Using this recombinant protein, we demonstrated that sFRP-1 and Wg (wingless) interact in enzyme-linked immunosorbent and co-precipitation assays. Surprisingly, a derivative lacking the cysteine-rich domain retained the ability to bind Wg. Cross-linking experiments performed with radioiodinated sFRP-1 provided definitive evidence that sFRP-1 and Wg bind directly to each other. Besides detecting a cross-linked complex consistent in size with 1:1 stoichiometry of sFRP-1 and Wg, we also observed a larger complex whose size suggested the presence of a second sFRP-1 molecule. The formation of both complexes was markedly enhanced by an optimal concentration of exogenous heparin, emphasizing the potential importance of heparan-sulfate proteoglycan in Wnt binding and signaling. sFRP-1 exerted a biphasic effect on Wg activity in an armadillo stabilization assay, increasing armadillo level at low concentrations but reducing it at higher concentrations. These results provide new insights about the Wnt binding and biological activity of sFRPs.
This article presents the authors' philosophy regarding the use of physical manipulation of the larynx and the neck in patients presenting with voice disorders from the context of the anatomy and physiology of the larynx. The biomechanics of the laryngeal structures are reviewed. Potential indications for manipulation are discussed. The examination of the larynx and perilaryngeal structures is presented from a mechanical standpoint. Some basic tenets in laryngeal manipulation, including potential risks and contraindications, are offered.
The use of inhaled steroids in the treatment of asthma is not without its complications. In some studies up to 50% of such patients complain of oropharyngeal and voice problems. We present the findings in 22 patients complaining of dysphonia who underwent videostrobolaryngoscopy (VSL) and computerized speech analysis. A number of abnormalities were identified. On VSL, these included mucosal changes (noted in 58%), apposition abnormalities (noted in 43%), and supraglottic hyperfunction (noted in 40%). On speech analysis, cycle-to-cycle irregularity was frequently noted (mean of 39%). Maximum phonation time was reduced in 73%. Our findings did not confirm the widely held views that steroid dysphonia is due primarily to a fungal infection or a steroid-induced adductor myasthenia of the larynx. A larger-scale prospective study is indicated.
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The ect2 oncogene was originally identified as a transforming complementary DNA (cDNA) from mouse epithelial cells in an expression cloning approach and encodes a product related to Rho-specific exchange factors and yeast cell cycle regulators. To explore the potential role of ect2 in the cell cycle, we examined the expression of the ect2 proto-oncogene in a liver regeneration model in mice after partial (two thirds) hepatectomy. We found that the expression of the ect2 transcript and protein were markedly elevated with the onset of DNA synthesis and remained elevated during G2 and M phases. The timing of ect2 expression matched that of proliferating cell nuclear antigen (PCNA) and partially overlapped cell division cycle 2 (Cdc2) expression. In situ hybridization analysis showed that ect2 was expressed at a high level in cells undergoing mitosis in regenerating liver. Moreover, expression of a dominant negative or an oncogenic mutant of ect2 in cultured mouse hepatocytes resulted in a large increase in the number of binucleated cells. These findings showed that Ect2 is expressed in a cell cycle-dependent manner during liver regeneration, and suggest that it has an important role in the regulation of cytokinesis.
We previously reported that keratinocyte growth factor (KGF) is up-regulated by the action of progesterone (P) in the primate endometrium, and we suggested that this protein is a likely mediator of P-dependent stromal-epithelial paracrine interactions in this tissue. At the end of the menstrual cycle, P levels fall, and the abundance of endometrial KGF transcripts decreases approximately 9-fold. In macaques, withdrawal of P induces the luteal-follicular transition (LFT), marked by menstrual sloughing of the functionalis zone and apoptotic regression of the basalis zone. Because KGF levels fall so dramatically during the LFT, we hypothesized that replacement with exogenous KGF during the LFT would prevent some of the endometrial changes seen after P withdrawal. Here we describe two studies of the effects of exogenously administered KGF during the LFT in rhesus macaques. In one experiment we administered KGF systemically to ovariectomized, juvenile rhesus macaques during an LFT induced by hormonal manipulations. KGF had dramatic proliferative effects on the bladder and salivary glands, known targets of KGF, but did not affect cell proliferation in the endometrium or block menstrual sloughing and bleeding. However, KGF strongly inhibited apoptosis in the basalis zone, increased glandular sacculation and folding in this zone, and had a marked trophic effect on the spiral arteries. In the second experiment we installed oviductal catheters in ovariectomized adult rhesus macaques and infused KGF directly into the uterine lumen during a hormonally induced LFT. Again, arteriotrophic, antiapoptotic, and basalis gland sacculation effects were observed in the absence of any effect on cell proliferation. We concluded that although KGF is mitogenic for many epithelial cell types, it does not play this role in the primate endometrium. Its most important roles may be to stimulate spiral artery growth and inhibit glandular apoptosis during the nonfertile menstrual cycle. Because its expression rises coincident with the time of implantation and because spiral arteries are essential to successful establishment of pregnancy, the role of KGF in the fertile menstrual cycle deserves further study.
Polymorphic epithelial mucin (PEM), the protein product of the gene muc-1, is a surface glycoprotein that is produced by a range of normal epithelial cells, but has been shown to be expressed at high levels in a range of adenocarcinomas. It has not been investigated extensively in head and neck related tissues, and not at all in head and neck squamous cell carcinomas (HNSCC). This immunohistochemical investigation using two monoclonal antibodies to muc-1 represents a baseline study of 18 HNSCC. In 13 cases, the glycoprotein was expressed at varying levels, usually in keratinizing foci. Although less prominent, expression was also present to some degree in nine of 23 control specimens of non-neoplastic mucosa, mostly at an epithelial level early in the parakeratinization process. Both antibodies showed a pattern of staining. The cellular basis for muc-1 expression is speculative at present and although it is at a lower level than in adenocarcinomas, it may help to provide further insight into epithelial cell differentiation in squamous cell carcinomas.
Day-case surgery is an integral part of otolaryngology, and many procedures can be performed as day-cases provided strict criteria are applied in the selection of patients. We reviewed patients who required unexpected admission from the day-case unit at the Royal National Throat, Nose and Ear Hospital, London between April 1997 and March 1998. The total number of patients undergoing surgery was 1642. Of the total, 29 (1.8%) had to be admitted unexpectedly for overnight stay: 24 of these patients had undergone nasal surgery, representing 5.4% of all the nasal procedures performed--and the cause of all these admissions was haemorrhage. Further analysis revealed 22 of these 24 nasal operations had included a septoplasty. The total number of septoplasties performed was 163; thus, septoplasty had an unexpected admission rate of 13.4%. This information has been used to formulate stricter guidelines for day-case septoplasty admissions in our unit.
Hepatocyte growth factor (HGF) is a heparin-binding, multipotent growth factor that transduces a wide range of biological signals, including mitogenesis, motogenesis, and morphogenesis. Heparin or closely related heparan sulfate has profound effects on HGF signaling. A heparin-binding site in the N-terminal (N) domain of HGF was proposed on the basis of the clustering of surface positive charges [Zhou, H., Mazzulla, M. J., Kaufman, J. D., Stahl, S. J., Wingfield, P. T., Rubin, J. S., Bottaro, D. P., and Byrd, R. A. (1998) Structure 6, 109-116]. In the present study, we confirmed this binding site in a heparin titration experiment monitored by nuclear magnetic resonance spectroscopy, and we estimated the apparent dissociation constant (K(d)) of the heparin-protein complex by NMR and fluorescence techniques. The primary heparin-binding site is composed of Lys60, Lys62, and Arg73, with additional contributions from the adjacent Arg76, Lys78, and N-terminal basic residues. The K(d) of binding is in the micromolar range. A heparin disaccharide analogue, sucrose octasulfate, binds with similar affinity to the N domain and to a naturally occurring HGF isoform, NK1, at nearly the same region as in heparin binding. (15)N relaxation data indicate structural flexibility on a microsecond-to-millisecond time scale around the primary binding site in the N domain. This flexibility appears to be dramatically reduced by ligand binding. On the basis of the NK1 crystal structure, we propose a model in which heparin binds to the two primary binding sites and the N-terminal regions of the N domains and stabilizes an NK1 dimer.