The Relationship Between Gender and Sexual Orientation in Academia

To date, there has been no prior systematic analysis of where LGB research gets published and where LGB studies programs are housed within universities. LGB research could have a disciplinary home in any number of areas of study because of its relevance across many disciplines. Nevertheless, drawing upon the theory of sexuality-as-gendered, we predicted that LGB research and programs of study would be found predominantly within gender studies. We examine the extent to which sexual orientation research (Study 1) and U.S. university LGBTQ-related academic programming (Studies 2 and 3) has found their home in the gender studies discipline. Study 1 results showed gender studies have been the primary home of published sexual orientation research in top-ranked peer-reviewed journals over the past three decades. In Study 2, university LGBTQ academic programming was housed within gender studies departments more frequently than any other department-including standalone LGBTQ studies departments. In Study 3, Google searches for university "LGBT studies" frequently led to that university's gender studies department website as the top search result-including universities whose gender studies department offered zero LGBTQ-related courses. Combined, these results demonstrate far-reaching manifestations of the fact that gender and sexuality are inextricably intertwined constructs.

Regional Measures of Sexual-Orientation Bias Predict Where Same-Gender Couples Live

Regional explicit and implicit bias are associated with real-world discrimination and marginalization. We extended this research area by focusing on sexual minorities and where same-gender couples live. Using data on 2,939 U.S. counties from Project Implicit and other publicly available sources, we found that measures with known associations with systemic anti-lesbian, gay, and bisexual (anti-LGB) bias are similarly associated with regional implicit and explicit anti-LGB bias. Furthermore, we found that fewer same-gender couples reside in counties with more explicit and implicit anti-LGB bias, above and beyond other factors that likely influence same-gender-couple residency. These findings further suggest that explicit and implicit measures of regional bias are capturing similar, if not the same, construct of a region's culture of bias toward particular groups. Couched specifically within the ongoing systemic political antagonization of the lesbian, gay, bisexual, transgender, queer, plus (LGBTQ+) community, these findings also highlight the importance of considering contextual (in addition to individual) factors that reinforce systemic inequality.

LGBT workplace protections as an extension of the protected class framework

OBJECTIVES

Many corporations in the United States have enacted nondiscrimination policies for their LGBT employees, despite that the LGBT community has not been a legally protected class concerning employment discrimination at the national level. We examined whether progressive corporate LGBT-related policies may be an extension of policies and practices designed to foster diversity and create equality for existing legally protected classes (women, ethnic minorities, veterans, and those with disabilities). We also examined whether leadership level diversity (percentage of women and ethnic minorities on company boards of directors) predicted nondiscrimination policies for LGBT employees.

HYPOTHESES

We predicted companies that have been recognized and awarded for protected class diversity policies and that have a greater percentage of women and racial/ethnic minorities on their boards of directors would have more progressive LGBT-related corporate policies.

METHOD

Using a sample of Fortune 500 companies, we examined protected-class diversity awards and percentage of women and racial/ethnic minorities on boards of directors as predictors of LGBT-related policies. At the company-level, we controlled for the average age of board, company size, and company revenue. At the level of company headquarter location, we controlled for political climate, Christian religiosity, and LGBT employment nondiscrimination laws. We also controlled for U.S. region and industry sector.

RESULTS

Multilevel modeling results indicated that protected-class diversity awards and the percentage of women on company boards of directors significantly and independently predicted progressive LGBT policy scores, whereas the percentage of racial/ethnic minorities on boards of directors had less consistent results.

CONCLUSION

Companies that address issues of diversity and equality in the workplace have been likely to include the LGBT community among their groups of concern, even in the absence of legal pressures to do so. (PsycInfo Database Record (c) 2020 APA, all rights reserved).

Malaria elimination in Haiti by the year 2020: an achievable goal?

Haiti and the Dominican Republic, which share the island of Hispaniola, are the last locations in the Caribbean where malaria still persists. Malaria is an important public health concern in Haiti with 17,094 reported cases in 2014. Further, on January 12, 2010, a record earthquake devastated densely populated areas in Haiti including many healthcare and laboratory facilities. Weakened infrastructure provided fertile reservoirs for uncontrolled transmission of infectious pathogens. This situation results in unique challenges for malaria epidemiology and elimination efforts. To help Haiti achieve its malaria elimination goals by year 2020, the Laboratoire National de Santé Publique and Henry Ford Health System, in close collaboration with the Direction d’Épidémiologie, de Laboratoire et de Recherches and the Programme National de Contrôle de la Malaria, hosted a scientific meeting on “Elimination Strategies for Malaria in Haiti” on January 29-30, 2015 at the National Laboratory in Port-au-Prince, Haiti. The meeting brought together laboratory personnel, researchers, clinicians, academics, public health professionals, and other stakeholders to discuss main stakes and perspectives on malaria elimination. Several themes and recommendations emerged during discussions at this meeting. First, more information and research on malaria transmission in Haiti are needed including information from active surveillance of cases and vectors. Second, many healthcare personnel need additional training and critical resources on how to properly identify malaria cases so as to improve accurate and timely case reporting. Third, it is necessary to continue studies genotyping strains of Plasmodium falciparum in different sites with active transmission to evaluate for drug resistance and impacts on health. Fourth, elimination strategies outlined in this report will continue to incorporate use of primaquine in addition to chloroquine and active surveillance of cases. Elimination of malaria in Haiti will require collaborative multidisciplinary approaches, sound strategic planning, and strong ownership of strategies by the Haiti Ministère de la Santé Publique et de la Population.

The contact hypothesis revisited: status bias in the reduction of implicit prejudice in the United States and Lebanon

Although 50 years of research demonstrate that friendly intergroup contact reduces intergroup prejudice, the findings are based solely on self-reported, explicit prejudice. In two parallel experiments examining intergroup contact and prejudice-between Whites and Blacks in the United States (Experiment 1) and between Christians and Muslims in Lebanon (Experiment 2)-we examined whether intergroup status differences moderate contact effects on implicit prejudice, as well as explicit prejudice. Both experiments replicated the standard effect of contact on explicit prejudice. They also demonstrated that intergroup contact reduces implicit prejudice among low-status groups. In Experiment 1, the implicit prejudice of Blacks toward Whites (but not Whites toward Blacks) was reduced as a function of friendly contact. In Experiment 2, the implicit prejudice of Muslims toward Christians (but not Christians toward Muslims) was reduced as a function of friendly contact.

Protease-activated receptors (PARs) are partly pro-inflammatory and partly anti-inflammatory: will PAR agonists or antagonists participate in future drug therapies?

Protease-activated receptors (PARs) are characterised by a unique mechanism of activation, which enables them to act as cellular sensors for protease activity. PARs are expressed throughout the cardiovascular, gastrointestinal and pulmonary systems, where they are potential drug targets for the treatment of disease. However, there are currently very few selective PAR antagonists or potent PAR agonists available as effective research tools, and moreover, there is considerable evidence to suggest that PARs can promote both pro-inflammatory and anti-inflammatory responses in a wide range of disease models. These confounding issues have, to date, prevented us from developing a clear understanding of the role of PARs in disease. Nevertheless, this review provides an overview of the distribution and function of PARs in the cardiovascular, gastrointestinal and pulmonary systems, and attempts to evaluate whether PAR agonists or antagonists have a place in future drug therapy.

Examining the principles in principled conservatism: the role of responsibility stereotypes as cues for deservingness in racial policy decisions

Why do educated conservatives oppose affirmative action? Those in the "principled conservatism" camp say opposition is based on principled judgments of fairness about the policies. Others, however, argue that opposition is based on racism. The present article offers an alternative perspective that may reconcile these contradictory points of view. In 2 studies, the authors show 2 major findings: (a) that conservatives oppose affirmative action more for Blacks than for other groups, in this case women, and (b) that the relationship between conservatism and affirmative action attitudes is mediated best by group-based stereotypes that offer deservingness information and not by other potential mediators like old-fashioned racism or the perceived threat that affirmative action poses to oneself. The authors conclude that educated conservatives are indeed principled in their opposition to affirmative action, but those principles are group based not policy based.

The origins of symbolic racism

The theory of symbolic racism places its origins in a blend of anti-Black affect and conservative values, particularly individualism. We clarify that hypothesis, test it directly, and report several findings consistent with it. Study 1 shows that racial prejudice and general political conservatism fall into 2 separate factors, with symbolic racism loading about equally on both. Study 2 found that the anti-Black affect and individualism significantly explain symbolic racism. The best-fitting model both fuses those 2 elements into a single construct (Black individualism) and includes them separately. The effects of Black individualism on racial policy preferences are mostly mediated by symbolic racism. Study 3 shows that Black individualism is distinctively racial, with effects distinctly different from either an analogous gender individualism or race-neutral individualism.

The origins of symbolic racism

The theory of symbolic racism places its origins in a blend of anti-Black affect and conservative values, particularly individualism. We clarify that hypothesis, test it directly, and report several findings consistent with it. Study 1 shows that racial prejudice and general political conservatism fall into 2 separate factors, with symbolic racism loading about equally on both. Study 2 found that the anti-Black affect and individualism significantly explain symbolic racism. The best-fitting model both fuses those 2 elements into a single construct (Black individualism) and includes them separately. The effects of Black individualism on racial policy preferences are mostly mediated by symbolic racism. Study 3 shows that Black individualism is distinctively racial, with effects distinctly different from either an analogous gender individualism or race-neutral individualism.

Interleukin-13 mediates airways hyperreactivity through the IL-4 receptor-alpha chain and STAT-6 independently of IL-5 and eotaxin

Interleukin (IL)-13 is a central mediator of the processes underlying the induction of airways hyperreactivity (AHR) in the allergic lung. However, the mechanisms by which IL-13 induces AHR and the associated role of inflammatory infiltrates as effector cells has not been fully elucidated. In this investigation, we show that intratracheal administration of IL-13 induces AHR in the presence and absence of inflammation. The initial AHR response (peak, 6 to 24 h; preinflammatory phase [PIP]) was dissociated from inflammation (eosinophilia) and mucus hypersecretion but was critically regulated by signaling through the IL-4 receptor alpha chain (IL-4Ralpha) and signal transducers and activators of transcription (STAT)-6. The second response (> 24 h, inflammatory phase [IP]) was characterized by an amplified AHR, eosinophil accumulation, and mucus hypersecretion. These features of the IP were not observed in IL-4Ralpha- or STAT-6-deficient mice. To determine the role of eosinophils in the induction of IP AHR and mucus hypersecretion, we administered IL-13 to IL-5-, eotaxin-, and IL-5/eotaxin- deficient mice. IL-13-mediated eosinophil accumulation was significantly attenuated (but not ablated) in IL-5-, eotaxin-, or IL-5/eotaxin-deficient mice. However, IL-13-induced AHR and mucus secretion occurred independently of IL-5 and/or eotaxin. These findings demonstrate that IL-13 can induce AHR independently of these eosinophil regulatory cytokines and mucus hypersecretion. Furthermore, IL-13-induced AHR, eosinophilia, and mucus production are critically dependent on the IL-4Ralpha chain and STAT-6.

The impact of inflammation on bronchial neuronal networks

It is well-recognized that the activities of airway neuronal systems can be modulated by various agonist molecules. This brief review examines some of the evidence that inflammation and some of the mediators relevant to the expression of inflammatory processes can also significantly alter the function and activities of airway nerves. The concept of neuronal plasticity and phenotype switching induced by inflammation is also examined, with particular emphasis on sensory airway nerves.

HeartSaver VAD: a totally implantable ventricular assist device. Results of in vivo studies

Currently, the most widely utilized ventricular assist devices (VADs) require percutaneous connections and are located either externally (e.g., Thoratec, Abiomed) or intra-abdominally (e.g., Novacor, TCI). These attributes have been implicated in a variety of complications (infection, thromboembolic, gastrointestinal, etc.). To address these concerns, a totally implantable VAD that requires no percutaneous connections and can be implanted in the left hemi-thorax has been developed. The developed device has undergone in vivo evaluation as part of the design and development process. A total of 43 implants in the bovine model, with 5 device versions, have been conducted between July 1992 and February 2000. These studies successfully have demonstrated several important aspects of the developed device, including 1) feasibility of a totally implantable system; 2) capability of the device to support a dysfunctional heart; and 3) ability of the device to provide flows up to 10 L/min in a physiological setting. The studies to date have played a vital role in the design and development process as well as demonstrating the feasibility of a totally implantable intrathoracic VAD. Based on these studies, design optimization was conducted, resulting in the development of the pre-clinical version of the device in preparation for clinical trials.

Influence of endothelin-1(1-31) on smooth muscle tone and cholinergic nerve-mediated contraction in rat isolated trachea

Endothelin-1(1-21) (ET-1(1-21)) is a strong candidate as a significant mediator in asthma, in part because of its powerful spasmogenic actions and its ability to enhance cholinergic nerve-mediated contraction in human and animal airway smooth muscle. In the study reported here, we have demonstrated that [125I]ET-1(1-31) binds specifically to BQ-123-sensitive sites (presumably ET(A)-receptors) and to sarafotoxin S6c (S6c)-sensitive sites (presumably ET(B)-receptors) in rat tracheal and pulmonary airways, as well as in lung alveoli. These sites coexist in tracheal airway smooth muscle and in alveolar tissue in approximately equal proportions. ET-1(1-21) and ET-1(1-31) were equipotent and approximately equally active as spasmogens in rat tracheal smooth muscle. Importantly, both peptides were shown to potentiate cholinergic nerve-mediated rat tracheal contraction, although ET-1(1-31) was less active in this regard. These data are consistent with the idea that ET-1(1-31) could play a significant mediator role in obstructive airway diseases such as asthma.

Tooth loss and implant replacement

Osseointegrated dental implants are increasingly used to replace missing teeth in a variety of situations ranging from the missing single tooth to complete edentulism. The implant possibility must be carefully considered because treatment involves extended time frames, considerable expense and is not without risk. Accordingly, treatment-planning decisions should have an evidence-based strategy with appropriate risk assessment. Implant systems need to be adequately tested before they are released for general use and success rates should be assessed from peer review scientific publication data and not commercial promotional literature. It is the responsibility of the dentist to ensure the patient is educated so an informed decision can be made on difficult treatment alternatives. The clinical decision making process must respect the issues to assure quality of care and reduction of liability for negligent care. Today, the three-unit fixed bridge can no longer be considered as the standard of care for restoration of a single missing tooth. The evidence has accumulated that the single tooth implant supported replacement is more conservative, more cost-effective and more predictable with respect to long-term outcome in uncomplicated cases.

Osseointegrated implants as an adjunct to facemask therapy: a case report

Branemark Implants were placed in the zygomatic buttresses of the maxilla in a 12-year and 1-month-old female patient with a Class III malocclusion caused by maxillary growth retardation secondary to repair of a unilateral cleft lip and palate defect. The implants were left to integrate for 6 months followed by placement of customized abutments that projected into the buccal sulcus. Elastic traction (400 g per side) was applied from a facemask to the implants at 30 degrees to the occlusal plane for 14 hours per day for 8 months (ages 12 years and 10 months to 13 years and 6 months). The maxilla moved downward and forward 4 mm rotating anteriorly as it was displaced. The change in the maxillary occlusal plane resulted in a secondary opening of the mandible. There was a 2 degrees increase in the SN-mandibular plane angle and an increase in nasion to menton distance of 9 mm. Clinically, this resulted in an increase in fullness of the infraorbital region and correction of the pretreatment mandibular prognathism. There was an increase in nasal prominence as the maxilla advanced. This contributed to the increase in facial convexity. The secondary dental change frequently seen in standard facemask therapy was avoided. The displacement of the maxilla was stable 1 year beyond cessation of facemask therapy. The patient's midface profile was improved by age of 13 years and 6 months. Details of the clinical procedure and treatment changes are presented.

Tissue regeneration adjacent to titanium implants placed with simultaneous transposition of the inferior dental nerve: a study in dogs

Transposition of the inferior alveolar nerve was performed in an experimental dog model. Four adult greyhounds were used in the study. Surgical transposition of the nerve was made bilaterally, and 3 implants were placed on each side while the nerve was lateralized. On one side, the nerve was repositioned in contact with the implants, while on the contralateral side a resorbable membrane was positioned between the implant surface and the neurovascular bundle. Histologic section after 4 months of healing showed an intimate contact between implants and nerve tissue in all cases without an interpositional membrane, in contrast to cases with membranes. Histomorphometric measurements of the distance between the implants and the nerve tissue showed that the membrane side had a considerably larger distance between the implant and the nerve, although not with concomitant bone formation.

Detection of endothelin receptors in rat and guinea-pig airway nerves by immunohistochemistry

We investigated the existence of endothelin (ET) receptor subtypes in airway neurones from the rat and guinea-pig and determined the ability of these receptors to modulate contractile function. Rat tracheal neuron cultures as well as rat and guinea-pig whole mount preparations were labelled with antibodies to the cholinergic nerve marker choline acetyltransferase (ChAT), the neuron specific marker protein gene product 9.5 (PGP 9.5) and to ET(A)and ET(B)receptors. Following incubation with fluorescent secondary antibodies, fluorescence was detected using confocal microscopy with dual emission protocols. Specific fluorescence was detected both in whole mount preparations and neuron cultures, in association with the primary antibodies. Specific fluorescence associated with either ET(A)and ET(B)receptors was colocalized with that for PGP 9.5. Despite the presence of ET(A)and ET(B)receptors on airway nerves, ET-1 failed to significantly alter cholinergic, excitatory or inhibitory non-adrenergic-non-cholinergic nerve-mediated responses in guinea-pig airways. This is in sharp contrast to ET-1-induced potentiation of responses to cholinergic nerve-evoked contraction in rat trachea. Thus, although ET(A)and ET(B)receptors exist in airway cholinergic neurons in whole mount preparations and in primary neuron cultures from rat and guinea-pig trachea, the influence of these receptors on contractile function appears to be species-dependent.

Endothelin-1 potentiates cholinergic nerve-mediated contraction in human isolated bronchus

That endothelin-1(ET-1) plays a mediator role in asthma is consistent with reports of ET-1-induced potentiation of cholinergic nerve-mediated contraction in airways from various animal species. This study examined the effect of ET-1 on cholinergic contractions in human isolated bronchus. Macroscopically nondiseased human bronchial tissue was obtained from 23 patients with respiratory tumours. An electrical field stimulation (EFS) frequency that produced one third of the contraction at 30 Hz (EFS30) was estimated. The effect of ET-1 on these EFS-evoked contractions was assessed. EFS-evoked contractions were frequency-dependent and abolished by either atropine or tetrodotoxin. Thus, EFS-induced contractions were mediated by acetylcholine from cholinergic nerves. ET-1 (3 nM) potentiated EFS-evoked contractions by 10+/-2% EFS30 (p<0.05) without any significant effect on contractions induced by exogenous acetylcholine. Neither the ET(A) receptor-selective antagonist BQ-123 (3 microM) nor the ET(B) receptor-selective antagonist BQ-788 (10 microM) alone significantly altered ET-1-induced potentiation of EFS-evoked contractions. However, in the combined presence of both BQ-123 and BQ-788, ET-1-induced potentiation of EFS-evoked contractions was abolished. Thus, prejunctional endothelinA and endothelinB receptors appear to mediate endothelin-1-induced potentiation of electrical field stimulation-evoked cholinergic contractions in human bronchus. This suggests another potentially important mechanism through which endothelin-1 could increase bronchial tone in asthma.

Implant anchorage for the occlusal management of developmental defects in children: a preliminary report

Congenital anomalies and developmental defects of the face and jaws often present orthodontic anchorage challenges in which the residual dentition cannot be adequately positioned for restorative objectives. This article presents a method of classification for the formulation of implant-based treatment protocols in children, reviews the application of implants in the developing dentition, and provides guidelines for occlusal treatment. Procedures performed according to the protocols outlined in this article will facilitate orthodontics and orthopedic movement and accelerate three-dimensional jaw movement by sutural distraction of basal bone.

Endothelins and asthma

In the decade since endothelin-1 (ET-1) and related endogenous peptides were first identified as vascular endothelium-derived spasmogens, with potential pathophysiological roles in vascular diseases, there has been a significant accumulation of evidence pointing to mediator roles in obstructive respiratory diseases such as asthma. Critical pieces of evidence for this concept include the fact that ET-1 is an extremely potent spasmogen in human and animal airway smooth muscle and that it is synthesised in and released from the bronchial epithelium. Importantly, symptomatic asthma involves a marked enhancement of these processes, whereas asthmatics treated with anti-inflammatory glucocorticoids exhibit reductions in these previously elevated indices. Despite this profile, a causal link between ET-1 and asthma has not been definitively established. This review attempts to bring together some of the evidence suggesting the potential mediator roles for ET-1 in this disease.

The role of endothelin in mediating virus-induced changes in endothelinB receptor density in mouse airways

Emerging evidence supports a mediator role for endothelin (ET)-1 in airway diseases including asthma. Respiratory tract viral infections, are associated with increased levels of ET and altered ET receptor density and function in murine airways. To determine whether these virus-induced effects are causally linked, perhaps involving ET-1-induced ET(B) receptor downregulation, the current study investigated the influence of in vivo administration of CGS 26303, an ET-converting enzyme inhibitor, on virus-induced changes in ET-content and ET(B) receptor density. CGS 26303 (5 mg x kg(-1) x day(-1)) or placebo was administered to mice via osmotic minipumps implanted subcutaneously. Two days after implantation, mice were inoculated with influenza A/PR-8/34 virus or sham-infected, and all measurements were performed on tissue obtained on the fourth day post-inoculation. Viral infection was associated with elevated levels of immunoreactive ET and decreased densities of ET(B) receptors in murine airways. Both of these effects were attenuated in virus-infected mice that had received CGS 26303. Virus-induced increases in wet lung weight were also inhibited by CGS 26303. Importantly, administration of CGS 26303 had no effect on the titres of infectious virus in the lungs and similarly, viral infection had no effect on the plasma levels of free CGS 26303. In summary, CGS 26303 inhibited the virus-induced changes in both immunoreactive endothelin content and endothelinB receptor density. These findings are consistent with the postulate that the elevated epithelial expression of endothelin-1 during respiratory tract viral infection is a contributing factor in the downregulation of endothelinB receptors in airway smooth muscle. Whether inhibitors of endothelin synthesis attenuate virus-induced exacerbations of asthma or airways hyperresponsiveness remains to be established.

Clinical experiences with dental implants

The clinical utilization of dental implants has accelerated in recent years, and new applications continue to emerge. Concomitantly, alternative implant systems have introduced conceptually different approaches to treatment using altered protocols. The purpose of this paper is to address some of the background issues pertinent to the long-term success, survival, safety, and effectiveness of these devices. The requirements for clinical acceptance of implants are controlled initially by regulatory bodies; however, the dentist eventually must make a decision on which type of implant should be used in clinical practice. This clinical decision-making process should involve the strategy of using an evidence-based approach to ensure quality of care and reduction of liability for negligent care. This is particularly the case when treatment is undertaken in identified high-risk categories. While short- to medium-term data have been accumulated on the success rates of several implant systems, it is apparent that long-term data comparing and contrasting the various advantages and disadvantages of different systems do not exist, and adequate criteria applicable to the collective clinical experience need to be defined. Expanding areas of application are dependent on continuous improvements in implant hardware, surgical protocol development, and rationalized osteopromotive and site installation augmentation technology. Many treatment endeavors are still largely at the pilot study level of development, and long-term prospective clinical trials on large numbers of patients are required to document results adequately and to elucidate the most likely productive areas for future investigation.

Typical endothelin ETA receptors mediate atypical endothelin-1-induced contractions in sheep isolated tracheal smooth muscle

Contraction of vascular and nonvascular smooth muscle induced by the endothelin/sarafotoxin family of peptides frequently does not readily fit into the current classification criteria for ETA and ETB receptors, raising the possibility of additional atypical receptors. In the current study, isometric tension recording and radioligand binding techniques were used to characterize the ETA receptor population in sheep isolated tracheal smooth muscle. Endothelin-1 and sarafotoxin S6b induced similar concentration-dependent contractions, although endothelin-1 was 2.6-fold more potent (P <.05, n = 15-18). The ETA receptor-selective antagonists BQ-123 and FR139317 caused concentration-dependent inhibition of the contractions induced by endothelin-1 and sarafotoxin S6b, but both antagonists were significantly less potent in inhibiting contractions induced by endothelin-1 than sarafotoxin S6b. For example, 0.03 microM FR139317 shifted the endothelin-1 and sarafotoxin S6b concentration-effect curves to the right by 1.8- and 8.3-fold, respectively (P <.01, n = 6-8). Although the observed agonist dependence of antagonist potency may indicate the presence of atypical ETA receptors, competition binding studies using 125I-endothelin-1 and 125-I-sarafotoxin S6b identified only a single population of BQ-123- and sarafotoxin S6b-sensitive ETA receptors. Additional association-, dissociation-, and saturation-binding studies revealed that 125I-endothelin-1 binding to these ETA receptors was pseudoirreversible, whereas 125I-sarafotoxin S6b binding was readily reversible. Thus, marked differences in the kinetic profiles of ETA receptor binding to endothelin-1, sarafotoxin S6b, and BQ-123, rather than the existence of another ETA receptor subtype, may explain the stark agonist dependence of antagonist potency observed in contractile studies.

A protective role for protease-activated receptors in the airways

The protection of cells in the upper intestine against digestion by pancreatic trypsin depends on the prostanoid prostaglandin E2 (PGE2) and is mediated by protease-activated receptors in the epithelium. As the airway epithelium is morphologically similar and also expresses one of these receptors, PAR2, and is a major source of PGE2, we reasoned that bronchial epithelial PAR2 might also participate in prostanoid-dependent cytoprotection in the airways. Here we show that activation of PAR2, which co-localizes immunohistochemically with trypsin(ogen) in airway epithelium, causes the relaxation of airway preparations from mouse, rat, guinea-pig and humans by the release of a cyclooxygenase product from the epithelium. This physiological protective response in isolated airways also occurred in anaesthetized rats, where activation of PAR2 caused a marked and prolonged inhibition of bronchoconstriction. After desensitization of PAR2, the response to trypsin recovered rapidly by mechanisms dependent on de novo synthesis and trafficking of proteins. Our results indicate that trypsin released from the epithelium can initiate powerful bronchoprotection in the airways by activation of epithelial PAR2.

Endothelin receptor distribution and function in the airways

1. Within the lung, endothelin (ET)-1 is synthesized and released by airway epithelial and vascular endothelial cells, as well as by inflammatory cells, such as macrophages. Following release, ET-1 can modulate the activities of a wide range of different cell types within the lung through the stimulation of specific endothelin ETA and ETB receptors. The present review focuses on recent advances in our understanding of the distribution and function of endothelin receptors within the airway wall and peripheral lung and, where possible, particular attention is given to studies using human cells, tissues and subjects. 2. The highest densities of endothelin receptors within the lung appear to be associated with airway smooth muscle and the alveolar septae. The relative proportions of ETA and ETB receptors present within these tissues display marked interspecies differences, although ETB receptors predominate at both sites in human lung. 3. The effects induced by ET-1 within the lung include contraction and proliferation of airway smooth muscle, facilitation of cholinergic neurotransmission, mucous gland hypersecretion, microvascular leakage and inflammatory cell influx and activation. There is also evidence that a proportion of ETB receptors in the pulmonary microvasculature act as clearance receptors for endothelin-1. 4. Evidence to date suggests that changes in the endothelin content within the airway wall, conceivably associated with lung pathology, are likely to have profound effects on the function of many cells within the lung.

Ca2+ signalling by endothelin receptors in rat and human cultured airway smooth muscle cells

1. The aim of the current study was to characterize the ET receptor subtypes in cultured airway smooth muscle cells derived from rat trachea and human bronchus using radioligand binding techniques and to investigate the coupling of ET receptors to intracellular calcium signalling mechanisms using endothelin receptor-selective agonists (sarafotoxin S6c) and antagonists (BQ-123, BQ-788) and digital image fluorescence microscopy. 2. Confluent rat airway smooth muscle cells in culture possessed a mixed ET receptor population (30% ETA : 70% ETB), with a density of approximately 3400+/-280 ETA and 8000+/-610 ETB receptors/cell (n = 3 experiments). The density of ETB, but not ETA receptors increased substantially in serum-containing medium. However, a 2-day period of serum deprivation, which inhibited cellular growth, substantially reduced ETB receptor density such that the ET receptor subtype proportions were approximately equal (55% ETA; 45% ETB) and similar to those previously observed in intact rat tracheal smooth muscle. 3. Challenge of rat airway smooth muscle cells in culture with endothelin- 1 elicited a concentration-dependent biphasic increase in [Ca2+]i (EC50: 16 nM), that comprised an initial transient peak [Ca2+]i increase (typically 350 nM) followed by a modest sustained component. The endothelin-1-induced biphasic [Ca2+]i increase was primarily due to ETA receptor activation, although a modest and inconsistent ETB response was observed. The ETA-mediated [Ca2+]i increase was due primarily to the mobilization of IP3-sensitive and to a lesser extent ryanodine-sensitive intracellular calcium stores. In contrast, ETB receptor activation was exclusively coupled to extracellular calcium influx. 4. Somewhat surprisingly, human airway smooth muscle cells in culture contained a homogeneous population of ETA receptors at a density of 6100+/-800 receptors cell(-1) (n = 3 experiments). Serum deprivation was without effect on either ET receptor subtype proportion or ETA receptor density. Challenge of human airway smooth muscle cells with endothelin-1 provoked a concentration-dependent increase in [Ca2+]i (EC50: 15 nM), with a peak [Ca2+]i increase to greater than 700 nM. Furthermore, the ETA-mediated calcium response in these human airway smooth muscle cells in culture was entirely dependent upon the mobilization of calcium from intracellular stores. 5. In summary, rat cultured tracheal airway smooth muscle cells contained both ETA and ETB receptors. ETA receptors, the numbers of which remained constant during cell growth, were linked to the release of Ca2+ from intracellular stores and a strong rise in [Ca2+]i in the majority of airway smooth muscle cells. In stark contrast, the numbers of ETB receptors increased significantly during cell growth, an effect that was diminished substantially by incubation in serum-free medium. Moreover, despite the greater number of ETB receptors, their activation in a small number of airway smooth muscle cells produced only a weak rise in [Ca2+]i, which appeared to be attributable to the influx of extracellular Ca2+. In contrast, the populations of ET receptors and their linkage to [Ca2+]i were markedly different in the human cultured airway smooth muscle cells used in the current study compared to that previously observed in intact human isolated bronchial smooth muscle.

Altered ETB- but not ETA-receptor density and function in sheep airway smooth muscle cells in culture

The possibility that significant changes in endothelin (ET)A- and ETB-receptor density and function occur in airway smooth muscle cells (ASMCs) during cell growth and extended cell culture was investigated in sheep tracheal ASMCs. As in intact tracheal smooth muscle tissue from this species, early-passage sheep ASMCs contained a homogeneous population of ETA receptors. However, growth of ASMCs from seeding to postconfluence and repeated passage of ASMCs (6th to 14th passages) was associated with a substantial increase in ETB-receptor density, with no change in ETA-receptor density. ET-1-induced stimulation of ETB receptors increased the intracellular Ca2+ concentration in single ASMCs. Interestingly, a 2-day period of serum deprivation completely eliminated the increase in ETB-receptor density and the ETB receptor-mediated change in intracellular Ca2+ concentration. In summary, growth and repeated passage of sheep ASMCs were associated with a profound and selective increase in the density and function of the ETB receptor, a receptor subtype not present in early-passage ASMCs and not detected in intact sheep tracheal airway smooth muscle.

Influence of respiratory tract viral infection on endothelin-1-induced modulation of cholinergic nerve-mediated contractions in murine airway smooth muscle

The effects of endothelin-1 (ET-1) and sarafotoxin S6c (S6c) on cholinergic contractions elicited by electrical field stimulation (EFS) were examined in mouse tracheal preparations from healthy animals and from animals infected with parainfluenza-1 (P-1) virus. S6c (an ETB-selective agonist) and ET-1 caused marked ETA and/or ETB receptor-mediated potentiation of EFS-induced contraction in tracheal tissue from both groups. Despite the fact that such infection is known to markedly alter ET receptor density and function in mouse tracheal smooth muscle, no evidence for modulated neuronal ET receptor function was obtained. The reason for this differential sensitivity of smooth muscle and neuronal ET receptors to P-1 infection is unknown.

Immunocytochemical detection of endothelin receptors in rat cultured airway nerves

Endothelin-1 (ET-1) has been shown to potentiate cholinergic neurotransmission in human bronchus as well as in airways from a variety of animal species, suggesting that ET receptors exist prejunctionally on airway cholinergic nerves. We have successfully isolated and maintained rat tracheal para-sympathetic neurons in culture. Most cultured cells were associated with specific fluorescence for the nerve cell marker protein gene product 9.5 (PGP 9.5). These cultures contained a high proportion of parasympathetic neurons. Importantly, specific immunofluorescent antibodies for ETB receptors were colocalized with those for PGP 9.5. Therefore, for the first time, ETB receptors have been shown to exist on airway parasympathetic neurons in culture.

Distribution of immunoreactive endothelin in the lungs of mice during respiratory viral infection

Respiratory tract viral infections are associated with the generation of a wide array of pro-inflammatory cytokines, some of which enhance the release of the potent airway smooth muscle spasmogen, endothelin, from respiratory epithelial cells in tissue culture. The aim of this study was to determine whether the content and distribution of immunoreactive endothelin in the intact murine lung is increased during the course of a respiratory tract viral infection. Mice were inoculated intranasally with Influenza A/PR-8/34 virus or sterile vehicle and at various days postinoculation were sacrificed, and their lungs processed for either fluorescence immunohistochemistry with rabbit anti-endothelin sera or measurement of immunoreactive endothelin with an enzyme-linked immunosorbent assay (ELISA). At 2 and 4 days postinoculation, the content of immunoreactive endothelin in lung extracts of virus-infected mice was approximately twice that present in lung extracts from control mice (n=3-4, p<0.05). Consistent with this, an increased intensity and broader distribution of fluorescent immunohistochemical staining for endothelin was observed in the airway epithelium of the trachea and intrapulmonary airways of virus-infected mice. This study has clearly demonstrated that respiratory tract viral infection is associated with an increased content and broader distribution of immunoreactive endothelin within the lungs of mice. Whether the elevated content of endothelin contributes to the symptoms of virus-induced hyperresponsiveness or to virus-induced exacerbations of asthma remains to be established.

Future therapeutic directions for management of the edentulous predicament

The 1982 Toronto Conference on Tissue-Integrated Prostheses introduced the technique of osseointegration to the academic dental community. Subsequently, prosthodontists have played a leading role in the educational and clinical development of implant-supported fixed and removable prostheses for the treatment of the edentulous jaw. The success rates of treatment in the mandible have been replicated in many parts of the world and results are rewarding when compared with conventional complete denture therapy. Unfortunately, treatment results in the maxilla do not parallel those in the mandible and the shortfall requires the development of alternative strategies in diagnosis, treatment planning, surgery, and prosthetic management. As these treatment concepts become an everyday practice reality, osseointegrated implants have predictably found their way into the curriculum of all dental specialties. However, in many localities, the role of the prosthodontist in continuing education and research and development has become diluted as other areas of dentistry realize the enormous potential for treatment with osseointegrated implants. Accordingly, prosthodontists need to reevaluate their clinical mind-set if the specialty is to provide a lead role in future therapeutic endeavors.

Establishing orally self-administered cocaine as a reinforcer in rats using home-cage pre-exposure

1. Rats were force-exposed to a cocaine + saccharin solution in their home cage water bottles for five days. They were then given 5 h home-cage access to both cocaine and cocaine-free solutions for 40 days. 2. The subjects consumed large doses of the cocaine solution despite the ad libitum availability of water. 3. The animals were then trained on a task consisting of operant bar pressing rewarded on an intermittent schedule with a liquid cocaine reinforcer. 4. All subjects performed the operant task and consumed doses of cocaine solution which are preferred over water in other paradigms. 5. Levels of responding were significantly reduced in three of four subjects when vehicle was substituted for liquid cocaine as the reward. 6. This demonstrates that orally self-administered cocaine can be used as a reinforcer in rats.

Tissue regeneration in bony defects adjacent to immediately loaded titanium implants placed into extraction sockets: a study in dogs

In this study of six greyhound mandibles, 24 implants were placed into extraction sockets. Eighteen of the implants were connected with abutments and immediately placed into normal function, and the remaining six submerged implants served as controls. At placement, dehiscence areas were created adjacent to 12 of the implants to study bone regeneration in extended membrane-protected defects. Six of the defects were covered with expanded polytetrafluoroethylene membranes, and six of the defects were augmented with autologous bone grafts and covered with expanded polytetrafluoroethylene material. The clinical and radiographic evaluations demonstrated that all implants achieved functional osseointegration and no implants were lost. Implant sites where membranes were used to regenerate bone over dehiscence defects demonstrated a high rate of membrane exposure and variable response to treatment. On completion of the study at 16 weeks, histomorphometric analysis demonstrated osseointegration with direct bone-to-implant contact for all implants, although the percentage of contact varied considerably. Histomorphometry indicates that the quality of osseointegration may be less favorable than the clinical and radiographic result would suggest.

Comparison of the contractile effects and binding kinetics of endothelin-1 and sarafotoxin S6b in rat isolated renal artery

1. To date, only two mammalian endothelin (ET) receptors, termed ETA and ETB, have been cloned, sequenced and characterized. However, several functional studies of isolated blood vessels suggest that ET-1-induced contractions may be mediated by multiple ETA receptors. In this study, the ETA receptors in renal arteries isolated from Wistar rats were characterized by isometric tension recording and radioligand binding techniques. 2. ET-1, sarafotoxin S6b (StxS6b) and ET-3 produced concentration-dependent contraction with similar response maxima in endothelium-denuded arteries, whereas the ETB receptor-selective agonist StxS6c was inactive. ET-1 and StxS6b were equipotent and 30 times more potent than ET-3. This agonist profile, together with the findings that the ETA receptor-selective antagonists, BQ-123 and FR-139317 caused concentration-dependent, rightward shifts of the concentration-effect curves to each agonist indicated that ET-1-induced contractions in rat renal artery were mediated via ETA receptors. 3. BQ-123 and FR-139317 were both significantly more potent inhibitors of contractions induced by StxS6b or ET-3 than of responses to ET-1, raising the possibility that a component of ET-1-induced contraction was mediated through atypical, BQ-123 (or FR-139317)-insensitive ETA receptors. However, in competition binding studies, specific [125I]-ET-1 and [125I]-StxS6b binding to rat renal artery sections was completely abolished by BQ-123 in a manner consistent with an action at a single site. Thus, competition binding studies did not provide any supportive evidence of the existence of a BQ-123-insensitive ETA receptor. 4. Additional studies revealed marked differences in the kinetics of [125I]-ET-1 and [125I]-StxS6b binding. Following a 3 h period of association of [125I]-ET-1 with its receptors, no significant dissociation of receptor-bound [125I]-ET-1 was observed during a 4 h washout period. In stark contrast, dissociation studies revealed that specific [125I]-StxS6b binding to ETA receptors was reversible (t0.5diss, 100 min). A series of association binding studies were also consistent with the specific binding of [125I]-ET-1 and [125I]-StxS6b being irreversible and reversible processes, respectively. 5. Thus, differences in BQ-123 potency against ET-1 and StxS6b-induced contractions in rat renal arteries might be due to differences in the kinetics of agonist binding, rather than due to the existence of atypical ETA receptors.

Fit discrimination of implant-supported fixed partial dentures fabricated from implant level impressions made at stage I surgery

STATEMENT OF PROBLEM

The implant level impression can shorten the overall time frame of implant treatment.

PURPOSE OF STUDY

The purpose of this study was to analyze the accuracy of fixed partial dentures constructed from impressions taken at implant installation surgery in partially edentulous dogs. The study compared the fit of welded titanium fixed partial dentures with that of cast gold alloy fixed partial dentures.

MATERIAL AND METHODS

Three implants were placed on each side of the mandible in six adult greyhound dogs during stage I surgery. Impressions were taken of the implant positional relationships and two types of fixed partial dentures were fabricated for each side of the mandible. Stage II surgery was performed after 3 months.

RESULTS

Both types of fixed partial dentures compared favorably with the fit of implant-supported fixed partial dentures in the edentulous jaw or traditional cast fixed partial denture frameworks.

CONCLUSIONS

Impressions taken at implant installation surgery provide a valid transfer of information for the laboratory fabrication of the final restoration when the implants are placed to fulfill the requirements of primary stability.

Is endothelin-1 a mediator in asthma?

There is a growing understanding of the effects and potential pathophysiological role of the ETs in asthma and several of the criteria required to strongly implicate ET-1 as a mediator in this disease have been fulfilled. However, some of the information is preliminary, equivocal and requires confirmation. Furthermore, the most important and most difficult criteria, the clinical testing of potent and selective ET receptor antagonists in these diseases has not been conducted and will probably not be completed for several years. A critical area of research continues to be the elucidation and classification of the ET receptor subtypes mediating the diverse effects of ET-1 in the lung. The unequivocal determination of the pathophysiological role of the ETs in asthma awaits the results of clinical trials with appropriate compounds. Only after these results will we know whether ET-1 has fulfilled its promise as a key player in lung pathophysiology, rather than being added to the list of purported important mediators with unfulfilled expectations.

Influence of endothelin-1 on cholinergic nerve-mediated contractions and acetylcholine release in rat isolated tracheal smooth muscle

The aim of this study was to assess the influence of endothelin-1 (ET-1) on cholinergic nerve-mediated contractions in rat isolated tracheal smooth muscle by use of electrical-field stimulation (EFS) and [3H]choline efflux studies. EFS (80 V, 0.5 ms, 0.1-30 Hz for 10 s) evoked transient, frequency-dependent contractions of isolated tracheal preparations. Contractions were abolished in the presence of atropine or tetrodotoxin, which suggests they were mediated by acetylcholine (ACh) release from cholinergic nerves. The ETB receptor-selective agonist sarafotoxin S6c (1 nM) augmented EFS (0.6-1 Hz)-induced contractions by 179%. These effects were significantly attenuated in the presence of the ETB receptor-selective antagonist N-cis-2,6-dimethylpiperidinocarbonyl-L-gamma-methyl-leucyl-D-1- methoxycarbonyltryptophanyl-D-norleucine (BQ-788; 1 microM). ET-1 (1 nM) also markedly potentiated EFS-induced contractions (153%). This was apparently not a postjunctional effect, because ET-1 did not alter contractile responses to exogenously applied ACh. Cyclo[D-Trp-D-Asp-L-Pro-D-Val-L-Leu] (BQ-123;3 microM) and BQ-788 when used alone, failed to inhibit ET-1-induced potentiation of EFS-evoked contractions. However, in their combined presence, BQ-123 and BQ-788 significantly attenuated ET-1-induced potentiation of EFS responses. EFS (100 V, 0.5 ms, 3 Hz for 2 min) applied to tracheal preparations preloaded with [3H]choline, caused airway smooth muscle contraction and an efflux of radioactivity. Both sarafotoxin S6c (10 nM) and ET-1 (10 nM) significantly enhanced the EFS-induced 3H-efflux and the latter was abolished only in the combined presence of BQ-123 and BQ-788. These data indicated that ET-1 enhances cholinergic nerve-mediated contractions in rat isolated trachea via activation of prejunctional ETA and ETB receptors that were linked to increased ACh release from cholinergic nerves.

Influence of respiratory tract viral infection on endothelin-1-induced potentiation of cholinergic nerve-mediated contraction in mouse trachea

1. This study examined the influence of respiratory tract infection with influenza A/PR-8/34 virus on endothelin receptor-mediated modulation of contraction induced by stimulation of cholinergic nerves in mouse isolated trachea. 2. The ETB receptor-selective agonist, sarafotoxin S6c (30 nM) induced large transient contractions (118 +/- 5% Cmax, n = 13; where Cmax is the contraction induced by 10 microM carbachol) of isolated tracheal segments from control mice. The peak contractile response to 30 nM sarafotoxin S6c was significantly lower in preparations from virus-inoculated mice at day 2 (57 +/- 8% Cmax, n = 3, P < 0.05) and 4 post-inoculation (90 +/- 8% Cmax, n = 9, P < 0.05), consistent with virus-induced attentuation of the ETB receptor-effector system linked to airway smooth muscle contraction. The mean peak contraction to 30 nM sarafotoxin S6c of preparations from virus-inoculated mice at day 8 post-inoculation (94 +/- 17% Cmax, n = 4) was not significantly different from that of control. 3. Electrical field stimulation (EFS; 90 V, 0.5 ms duration, 10 s train, 0.1-30 Hz) of preparations from control and virus-inoculated mice, caused contractions that were abolished by 0.1 microM atropine or 3 microM tetrodotoxin, indicating that these responses were mediated by neuronally released acetylcholine. Sarafotoxin S6c markedly potentiated contractions induced by a standard stimulus (0.3 Hz, every 3 min) in tracheal segments from control and virus-inoculated mice. In tracheal tissue from control mice, 30 nM sarafotoxin S6c significantly increased a standard EFS-induced contraction of 24 +/- 4% Cmax by a further 24 +/- 3% Cmax (i.e. 2 fold increase, n = 11). Sarafotoxin S6c (30 nM) also markedly potentiated standard EFS-induced contractions in preparations from virus-inoculated mice at day 2 (17 +/- 2% Cmax, n = 3), day 4 (17 +/- 5% Cmax, n = 9) and day 8 (26 +/- 5% Cmax, n = 4) post-inoculation. The level of potentiation of EFS-induced contractions in preparations from virus-inoculated mice was similar to that in tissue from control mice at days, 2, 4 and 8 post-inoculation. In contrast, sarafotoxin S6c (30 nM) did not enhance contractile responses of tracheal segments from control and virus-inoculated mice to exogenously applied acetylcholine (n = 3). 4. Endothelin-1 (1 nM) caused similar potentiations of standard EFS-induced contractions in tracheal segments from control (13 +/- 2% Cmax, n = 23) and virus-inoculated mice at day 2 (13 +/- 1% Cmax, n = 5), day 4 (16 +/- 5% Cmax, n = 6), and day 8 (13 +/- 3% Cmax, n = 8) post-inoculation. In contrast, 1 nM endothelin-1 did not enhance contractile responses of tracheal segments from control and virus-inoculated mice to exogenously applied acetylcholine (n = 4). Neither the ETA receptor-selective antagonist, BQ-123 (3 microM) nor the ETB receptor-selective antagonist, BQ-788 (1 microM) alone had any significant inhibitory effect on endothelin-1-induced potentiations of tracheal segments from control or virus-inoculated mice at days 2, 4 and 8 post-inoculation. However, simultaneous pre-incubation with BQ-123 (3 microM) and BQ-788 (1 microM) prevented endothelin-1-evoked potentiations, indicative of a role for both ETA and ETB receptors in this system. 5. These data clearly demonstrate that respiratory tract viral infection attenuated the function of the postjunctional ETB receptor-effector system linked directly to airway smooth muscle contraction. However, the function of prejunctional ETA and ETB receptor-effector systems linked to augmentation of cholinergic nerve-mediated airway smooth muscle contraction remained unaffected during respiratory tract viral infection in mice.

Secondary alveolar bone grafting--five-year periodontal and radiographic evaluation in 100 consecutive cases

A prospective study of secondary alveolar bone grafting based on the Norwegian (Oslo) team approach has been conducted by the CLP Unit at the Princess Margaret Hospital for Children in Perth, Australia, since 1982. The 5-year results of 100 consecutive cases of uni- and bilateral cases are presented according to periodontal and radiographic parameters of tooth support. The vast majority of cases grafted (98%) resulted in the eventual eruption of the cleft side cuspid/lateral incisor within acceptable parameters of tooth support. The results confirm the predictability of this safe procedure when utilized within a strict clinical protocol involving the whole CLP team.

Influence of parainfluenza-1 respiratory tract viral infection on endothelin receptor-effector systems in mouse and rat tracheal smooth muscle

1. In this study we have compared the effects of parainfluenza-1 respiratory tract viral infection on the density and function of ETA and ETB receptors in rat and mouse tracheal airway smooth muscle. 2. The bronchoconstrictor effect of inhaled methacholine was significantly enhanced in virus-infected rats, at both 4 and 12 days post-inoculation. That is, the concentration of methacholine causing an increase in resistance of 100% (PC100 methacholine) was significantly lower in virus-infected animals at both 4 and 12 days post-inoculation (n = 6-8; P < 0.05). 3. Total specific binding of [125I]-endothelin-1 and the relative proportions of ETA and ETB binding sites for [125I]-endothelin-1 were assessed in tracheal airway smooth muscle in parainfluenza-1-infected rats and mice at days 2, 4 and 12 post-inoculation using the ligands BQ-123 (1 microM; ETA receptor-selective) and sarafotoxin S6c (100 nM; ETB receptor-selective). Total specific binding in mice was significantly reduced at day 2 post-inoculation (n = 5; P < 0.05) but not at days 4 and 12 post-inoculation (n = 5). In control mice, the proportions of ETA and ETB binding sites were 53%:47% at day 2 and 43%:57% at day 4 and these were significantly altered by parainfluenza-1 infection such that, the ratios were 81%:19% at day 2 and 89%:11% at day 4 (P < 0.05). By day 12 post-inoculation, the proportion of ETA and ETB binding sites in tracheal smooth muscle from mice infected with parainfluenza-1 was not significantly different from control. In rat tracheal airway smooth muscle, neither total specific binding nor the ETA and ETB binding site ratio (64%:36%) were significantly altered in virus-inoculated rats at days 2, 4 or 12 post-inoculation (n = 5). 4. Parainfluenza-1 infection in mice had no effect on the sensitivity or maximal contractile effect of endothelin-1 in tracheal smooth muscle at days 2, 4 or 12 post-inoculation (n = 4). In contrast, contraction in response to the ETB receptor-selective agonist sarafotoxin S6c was attenuated by 39% at day 2 and by 93% at day 4 post-inoculation (P < 0.05). However, by day 12 post-inoculation, contractions to sarafotoxin S6c were not significantly different between control and virus-infected mice. In parainfluenza-1-infected rats, there were small but significant reductions in the sensitivity to carbachol, endothelin-1 and sarafotoxin S6c whilst the maximal responses to the highest concentrations of these agonists were not significantly altered by virus infection (n = 8). 5. BQ-123 (3 microM) had no significant effect on cumulative concentration-effect curves to endothelin-1 in tracheal preparations from control mice (n = 4) or parainfluenza-1-infected rats (n = 8). In contrast, in tissues taken from virus-infected mice at day 4 post-inoculation, BQ-123 caused a marked 9.6 fold rightward shift in the concentration-effect curve to endothelin-1 (n = 4). 6. In summary, we have demonstrated that parainfluenza-1 infection in mice transiently reduced the density of tracheal airway smooth muscle ETB receptors and this was reflected in reduced responsiveness to the ETB receptor-selective agonist sarafotoxin S6c. In contrast, whilst parainfluenza-1 infection in rats was associated with the pathological features and bronchial hyperresponsiveness common to respiratory tract viral infection, there was no selective down-regulation of ETB receptor expression or functional activity. The reasons for these species differences are not clear, but may relate to differences in the airway inflammatory response to parainfluenza-1 virus.

EndothelinB (ETB) receptor-activated potentiation of cholinergic nerve-mediated contraction in human bronchus

In human isolated bronchial preparations, the endothelinB (ETB) receptor-selective agonist, sarafotoxin S6c (Stx6c; 1 nM) increased nerve-mediated contraction in response to electrical field stimulation (EFS) at 0.5-1 Hz from 19 +/- 4% to 42 +/- 7% (n = 9). This effect was blocked in the presence of the ETB receptor-selective antagonist, BQ-788 (10 microM). These data are consistent with findings in some animal species that ET-1 and related peptides have marked neuromodulatory influences on the cholinergic system. Furthermore, they provide additional support for the concept that ET-1 may have a mediator role in bronchial obstruction in asthma.

Osseointegrated implants for single-tooth replacement: a prospective 5-year multicenter study

One hundred seven Brånemark implants were placed in 92 patients participating in an international multicenter trial on single-implant restorations at seven centers. The patients were followed for 5 years in a prospective study focusing on implant success and crown function. Plaque and gingival indexes, as well as probing depths, were recorded around teeth and implants. The marginal bone level at implants was determined from intraoral radiographs. Only three implants (2.8%) had been lost at the final annual checkup. During the follow-up period, a total of 17 patients dropped out or were excluded because of nonconformity with the protocol. Based on the remaining patients, a total of 86 implants were clinically and radiographically evaluated at the 5-year follow-up period, resulting in a cumulative success rate of 96.6% (71 implants) in the maxillae and 100% (15 implants) in the mandibles. Plaque and gingival indexes showed a similar pattern of good health around both natural teeth and titanium abutments. The marginal bone loss during the 5-year period did not exceed 1 mm as a mean for all implants analyzed. The most frequent complication recorded during the follow-up was loosening of the abutment fixation screw. The outcome of this study indicated that safe and highly predictable results can be obtained for 5 years when Brånemark implants are used to support single-tooth restorations.

Inhibition by endothelin-1 of cholinergic nerve-mediated acetylcholine release and contraction in sheep isolated trachea

1. The relative roles of ETA and ETB receptor activation on cholinergic nerve-mediated contraction and acetylcholine (ACh) release were examined in sheep isolated tracheal smooth muscle. 2. Electrical field stimulation (EFS; 90 V, 0.5 ms duration, 1 Hz, 10 s train) applied to sheep isolated tracheal smooth muscle strips induced monophasic contractile responses that were abolished by either 1 microM tetrodotoxin or 0.1 microM atropine, but were insensitive to 10 microM hexamethonium and 100 microM L-NAME. Thus, EFS-induced contractions resulted from the spasmogenic actions of ACh released from parasympathetic, postganglionic nerves. 3. As expected, sheep isolated tracheal smooth muscle preparations did not contract in response to the ETB receptor-selective agonist, sarafotoxin S6c (0.1-100 nM). However, sarafotoxin S6c caused a concentration-dependent and transient inhibition of EFS-induced contractions. The inhibitory effect induced by a maximally effective concentration of sarafotoxin S6c (10 nM; 72.1 +/- 5.7%, n = 6) was abolished in the presence of the ETB receptor-selective antagonist BQ-788 (1 microM). Contractile responses to exogenously administered ACh (10 nM-0.3 mM) were not inhibited by sarafotoxin S6c (1 or 10 nM; n = 7). 4. In contrast to sarafotoxin S6c, endothelin-1 induced marked contractions in sheep isolated tracheal smooth muscle. These contractions were inhibited by BQ-123, consistent with an ETA receptor-mediated response. In the presence of BQ-123 (3 microM), endothelin-1 produced a concentration-dependent inhibition of EFS-induced contractions (30 nM endothelin-1, 68.9 +/- 10.2% inhibition, n = 5). These responses were inhibited by 1 microM BQ-788, indicative of an ETB receptor-mediated process. Endothelin-1 was about 3 fold less potent than sarafotoxin S6c. 5. EFS (90 V, 0.5 ms duration, 1 Hz, 15 min train) induced the release of endogenous ACh (1.94 +/- 0.28 pmol mg-1 tissue, n = 12), as assayed by h.p.l.c. with electrochemical detection. EFS-induced release of ACh was inhibited to a similar extent by 100 nM endothelin-1 (47 +/- 4%, n = 9) and 10 nM sarafotoxin S6c (46 +/- 9%, n = 3). These effects of endothelin-1 on ACh release were inhibited by 1 microM BQ-788 alone (n = 4), by BQ-788 in the presence of 3 microM BQ-123 (n = 4), but not by 3 microM BQ-123 alone (n = 5). 6. In summary, sheep isolated tracheal smooth muscle contains two anatomically and functionally distinct endothelin receptor populations. ETA receptors located on airway smooth muscle mediate contraction, whereas ETB receptors appear to exist on cholinergic nerves that innervate tracheal smooth muscle cells and mediate inhibition of ACh release. The inhibitory effect of ETB receptor stimulation on cholinergic neurotransmission is in stark contrast to the enhancing effects hitherto described in the airways.

The endothelins in the pulmonary system

Although initial research interest in the ETs was focused on their cardiovascular effects, it is now clearly established that these peptides have wide-ranging activities in the respiratory track. Importantly, ET-1 is synthesized, stored, released and metabolized in the lung, suggesting that these activities may be relevant to both physiological function and pathophysiological processes in the lung. To the present time, only two ET receptor subtypes have been definitively characterized in the lung, namely ETA and ETB receptors, both of which have been shown to mediate contraction and mitogenesis in airway smooth muscle from humans and animals. However, the possibility that further receptor subtypes might be defined from functional, biochemical, and molecular biological studies cannot be dismissed. It is apparent that the ETs may have a role to play in the pathogenesis of several pulmonary diseases. However, most of the current evidence for this falls short of establishing convincing causal associations. Perhaps the most convincing data relate to pulmonary hypertension. Although it is too early to ascribe a role for the ETs in the pathophysiology of asthma, the preliminary data are intriguing. Thus far, research has centered largely on the bronchoconstrictor effects of ET-1 in vitro and in vivo. In relation to asthma, it is important that future studies should focus increasingly on the effects of the ETs in nerves and inflammatory cells. In addition, the effects of chronic airway exposure to ET-1 on smooth muscle and fibroblast proliferation is an important area for future research. The unequivocal testing of the pathophysiological role of the ETs in asthma requires the clinical evaluation of potent and selective receptor antagonists for the various ET receptor subtypes. It seems likely that these studies will be conducted in the not-too-distant future, as compounds which possess the appropriate pharmacological profile become available for clinical evaluation. Additionally, ECE-1 and ECE-2 present as potentially important targets for therapeutic intervention, although the development of selective nonpeptide inhibitors may be some years away.

Time course of changes in ETB receptor density and function in tracheal airway smooth muscle during respiratory tract viral infection in mice

1. In the current study, the density and function of ETA and ETB receptors in mouse tracheal airway smooth muscle were determined over the time course of respiratory tract infection with influenza A/PR-8/34 virus. 2. Quantitative autoradiographic studies using [125I]-endothelin-1 revealed that the tracheal airway smooth muscle from control mice contained ETA and ETB sites in the ratio of 49%:51% (+/- 2%, n = 29 mice). Respiratory tract viral infection was associated with increases in the density of ETA sites and decreases in the density of ETB sites at days 1, 2 and 4 post-inoculation which were reversible by day 19. For example, at day 4 post-inoculation, a time when the manifestations of viral infection were at or near their peak, the ratio of ETA:ETB sites was 72%:28% (+/- 4%, n = 6 mice, P < 0.05). In contrast, at day 19 post-inoculation, by which time viral infection had essentially resolved, the ratio of ETA:ETB sites was similar to control (51%:49% (+/- 3%), n = 6 mice). 3. Endothelin-1 was a potent spasmogen in isolated tracheal airway smooth muscle preparations from control mice (ED70 = concentration producing 70% of contraction induced by 10 microM carbachol = 6.3 nM (95% confidence limits, 4.0-10; n = 6 mice)). Neither the ETA receptor-selective antagonist, BQ-123 (3 microM), nor the ETB receptor-selective antagonist, BQ-788 (1 microM) alone had any significant inhibitory effect on endothelin-1-induced contractions of mouse isolated tracheal smooth muscle. However, simultaneous treatment with BQ-123 (3 microM) and BQ-788 (1 microM) resulted in a 10 fold rightward shift in the concentration-effect curve to endothelin-1 (ED70 = 60 nM, (44-90; n = 6 mice, P < 0.05)), indicating that contraction was mediated via both ETA and ETB receptors. 4. Endothelin-1 evoked similar concentration-dependent contractions of tracheal smooth muscle isolated from control and virus-inoculated mice. In the presence of the ETB receptor-selective-antagonist, BQ-788 (1 microM), the potency and maximum response to endothelin-1 were similar in preparations from control and virus-inoculated mice at all time points investigated. However, unlike control responses, endothelin-1-induced contractions in preparations from virus-infected mice were significantly inhibited by the ETA receptor-selective antagonist, BQ-123. For example, at day 4 post-inoculation, the contractile response to 30 nM endothelin-1, in the presence of BQ-123 (3 microM), was only 20 +/- 12% (n = 6 mice, P < 0.05) of that produced in control preparations under similar conditions. However, at day 19 post-inoculation, contraction evoked by 30 nM endothelin-1 in the presence of BQ-123 (3 microM), was similar to that in preparations from control mice. 5. In summary, during the early stages (days 1-8 post-inoculation) of respiratory tract infection with influenza A/PR-8/34 virus, we observed decreases in the density of tracheal airway smooth muscle ETB receptors which were reflected in decreases in ETB receptor-mediated airway smooth muscle contraction. In addition, during the same period of viral infection we observed increases in the density of tracheal airway smooth muscle ETA receptors which were not associated with increased function of the ETA receptor-effector system linked to contraction. Virus-associated modulation of ETA and ETB receptor density and function was reversible with recovery from infection.

The distribution and density of receptor subtypes for endothelin-1 in peripheral lung of the rat, guinea-pig and pig

1. Quantitative autoradiographic studies were conducted to determine the distributions and densities of endothelin-A (ETA) and ETB receptor subtypes in peripheral lung alveolar wall tissue of the rat, guinea-pig and pig, with a view to assessing the potential suitability of these tissues as models for investigations of ET receptor function in human alveolar tissue. 2. High levels of specific [125I]-ET-1 binding were detected in peripheral lung components from all three species tested. In mature porcine alveolar wall tissue, specific binding increased in a time-dependent manner to a plateau, consistent with the previously described pseudo-irreversible binding of this ligand to a finite population of specific binding sites. 3. [125I]-ET-1 was associated specifically with both ETA and ETB binding site subtypes in alveolar wall tissue of foetal pig lung as early as 36 days gestation, raising the possibility of a functional role for ET-1 in lung development. In addition, both ETA and ETB binding site subtypes were detected in alveolar wall tissue and in peripheral airway smooth muscle of mature lung parenchyma from all three species. However, the binding subtype proportions differed in these tissues. For example, in porcine peripheral bronchial smooth muscle, ETA sites apparently predominated, whereas ETB sites constituted the major subtype detected in alveolar wall in this species. These data suggest significant shifts in ET receptor subtype expression at different levels in the respiratory tract. 4. ET binding site subtype proportions in the alveolar wall also differed markedly between species. In rat lung alveoli, ETA and ETB sites were detected in similar proportions (52 +/- 3% and 43 +/- 5% respectively). In contrast, in guinea-pig peripheral lung, ETB binding sites clearly predominated, constituting approximately 80% of total specific binding, with ETA sites accounting for only 12%. Porcine alveolar wall tissue also contained a mixture of these ET receptor subtypes, with ETA and ETB binding comprising 23 +/- 3% and 65 +/- 1% respectively of the total population of specific binding sites detected. These latter proportions are similar to values previously obtained in human peripheral lung tissue, suggesting that porcine lung might be a useful model of the human peripheral lung in subsequent studies of the functions of these pulmonary ET receptor subtypes.

Influence of regional differences in ETA and ETB receptor subtype proportions on endothelin-1-induced contractions in porcine isolated trachea and bronchus

1. Quantitative autoradiographic studies were conducted to determine the distributions and densities of ETA and ETB binding site subtypes in porcine tracheal and bronchial smooth muscle. In addition, the roles of ETA and ETB receptors in endothelin-1-mediated contraction of these tissues were assessed. 2. Quantitative autoradiographic studies revealed that both ETA and ETB binding sites for [125I]-endothelin-1 were present in both bronchial and tracheal airway smooth muscle. However, the proportions of these sites were markedly different at these two levels within the respiratory tract. In tracheal smooth muscle, the proportions of ETA and ETB sites were 30 +/- 1% and 70 +/- 1% respectively, whereas in bronchial smooth muscle, these proportions were virtually reversed, being 73 +/- 2% and 32 +/- 8% respectively. 3. Endothelin-1 induced concentration-dependent contraction of porcine tracheal and bronchial airway smooth muscle. Endothelin-1 had similar potency (concentration producing 30% of the maximum carbachol contraction, Cmax) in trachea (22 nM; 95% confidence limits (c.l.), 9-55 nM; n = 9) and bronchus (22 nM; c.l., 9-55 nM; n = 6). Endothelin-1 also produced comparable maximal contractions in trachea (59 +/- 5% Cmax; n = 9) and bronchus (65 +/- 4% Cmax, n = 6). 4. In trachea, endothelin-1 induced contractions were not significantly inhibited by either the ETA receptor-selective antagonist, BQ-123 (3 microM) or the ETB receptor-selective antagonist, BQ-788 (1 microM). However, in the combined presence of BQ-123 and BQ-788, the concentration-effect curve to endothelin-1 was shifted to the right by 3.7 fold (n = 8; P = 0.01). 5. In bronchus, concentration-effect curves to endothelin-1 were shifted to the right by BQ-123 (3 microM; 4.3 fold; P < 0.05), but not by BQ-788 (1 microM). In the presence of both antagonists, concentration-effect curves to endothelin-1 were shifted by at least 6.7 fold (n = 6; P = 0.01). 6. Sarafotoxin S6c induced contraction in both tissue types, although the maximum contraction was greater in trachea (53 +/- 7% Cmax; n = 6) than in bronchus (21 +/- 5% Cmax; n = 6). BQ-788 (1 microM) markedly reduced sarafotoxin S6c potency in both trachea and bronchus (e.g. by 50 fold in trachea; c.l., 14-180; n = 6; P < 0.05). 7. These data demonstrate that the proportions of functional endothelin receptor subtypes mediating contraction of airway smooth muscle to endothelin-1, vary significantly at different levels in the porcine respiratory tract.

Endothelin-1 receptor density, distribution, and function in human isolated asthmatic airways

The potent bronchoconstrictor and mitogenic actions of the peptide endothelin-1 (ET-1) on airway smooth muscle may contribute significantly to the bronchial obstruction observed in asthma. However, the status of the receptor-effector systems that mediate these actions of ET-1 in asthmatic airways is currently unknown. Thus, we have used quantitative autoradiographic and isometric-tension recording techniques to evaluate the density, distribution, and function of the specific receptors that mediate the actions of ET-1 in both asthmatic and nonasthmatic airways. Here, we report that similar numbers of specific binding sites for [125I]-ET-1 exist in asthmatic and nonasthmatic airways, with the greatest densities located in airway smooth muscle in both tissue types. The ETB-receptor subtype constituted approximately 82% and 88% of these receptors for ET-1 in asthmatic and nonasthmatic human bronchial smooth muscle, respectively, and mediated contraction in response to this peptide. In addition, a component of ET-1-induced contraction appeared to be mediated by a non-ETB, BQ-123-resistant mechanism. Furthermore, a small population of ETA sites was identified that did not mediate contraction, but which may have a role in ET-1-induced prostanoid release and airway smooth-muscle proliferation. Interestingly, bronchial smooth muscle from asthmatic lung was significantly less sensitive to the contractile effects of ETB receptor activation, consistent with desensitization of this receptor subtype in response to the increased production and release of ET-1 that occurs in this disease.