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Introduction: Early detection may lead to reduced morbidity and mortality from melanoma. This study aims to establish guidelines for selecting patients suitable for digital monitoring of skin lesions., Methods: A literature review was conducted, followed by consensus among experts appointed by the Israeli Dermatology Association., Results: Two effective methods for early melanoma diagnosis were identified: Total-body photography (TBP) and digital dermoscopy. TBP involves capturing clinical images of the entire skin area for long-term monitoring (6-12 months). Digital dermoscopy focuses on close-up images of distinct lesions for short-term monitoring (3-4 months). Various risk factors for melanoma were identified, including genetic and familial factors, as well as demographic and phenotypic characteristics. Based on these risk factors and feasibility of clinical follow-up, a comprehensive list of indications for TBP was developed, categorized into three groups based on the expected level of benefit. Digital dermoscopy surveillance is recommended for patients with flat or slightly raised skin lesions showing dermoscopic features that do not definitively indicate melanoma., Discussion: TBP significantly improves early melanoma detection, enhancing sensitivity and specificity while reducing unnecessary biopsies. However, due to its high cost and limited coverage by the Israeli public health care system, prioritizing patients who would benefit most from TBP is crucial. The compiled list of indications aligns with international recommendations and provides further details within the article.

In this brief Commentary, Neal Nathanson recounts his memories of the metamorphosis of the American Journal of Hygiene into the American Journal of Epidemiology, and his subsequent service as the Editor-in-Chief from 1964 to 1979., (© The Author(s) 2022. Published by Oxford University Press on behalf of the Johns Hopkins Bloomberg School of Public Health. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.)

Despite a great deal of prior research, the early pathogenic events in natural oral poliovirus infection remain poorly defined. To establish a model for study, we infected 39 macaques by feeding them single high doses of the virulent Mahoney strain of wild type 1 poliovirus. Doses ranging from 10 7 to 10 9 50% tissue culture infective doses (TCID 50 ) consistently infected all the animals, and many monkeys receiving 10 8 or 10 9 TCID 50 developed paralysis. There was no apparent difference in the susceptibilities of the three macaque species (rhesus, cynomolgus, and bonnet) used. Virus excretion in stool and nasopharynges was consistently observed, with occasional viremia, and virus was isolated from tonsils, gut mucosa, and draining lymph nodes. Viral replication proteins were detected in both epithelial and lymphoid cell populations expressing CD155 in the tonsil and intestine, as well as in spinal cord neurons. Necrosis was observed in these three cell types, and viral replication in the tonsil/gut was associated with histopathologic destruction and inflammation. The sustained response of neutralizing antibody correlated temporally with resolution of viremia and termination of virus shedding in oropharynges and feces. For the first time, this model demonstrates that early in the infectious process, poliovirus replication occurs in both epithelial cells (explaining virus shedding in the gastrointestinal tract) and lymphoid/monocytic cells in tonsils and Peyer's patches (explaining viremia), extending previous studies of poliovirus pathogenesis in humans. Because the model recapitulates human poliovirus infection and poliomyelitis, it can be used to study polio pathogenesis and to assess the efficacy of candidate antiviral drugs and new vaccines. IMPORTANCE Early pathogenic events of poliovirus infection remain largely undefined, and there is a lack of animal models mimicking natural oral human infection leading to paralytic poliomyelitis. All 39 macaques fed with single high doses ranging from 10 7 to 10 9 TCID 50 Mahoney type 1 virus were infected, and many of the monkeys developed paralysis. Virus excretion in stool and nasopharynges was consistently observed, with occasional viremia; tonsil, mesentery lymph nodes, and intestinal mucosa served as major target sites of viral replication. For the first time, this model demonstrates that early in the infectious process, poliovirus replication occurs in both epithelial cells (explaining virus shedding in the gastrointestinal tract) and lymphoid/monocytic cells in tonsils and Peyer's patches (explaining viremia), thereby supplementing historical reconstructions of poliovirus pathogenesis. Because the model recapitulates human poliovirus infection and poliomyelitis, it can be used to study polio pathogenesis, candidate antiviral drugs, and the efficacy of new vaccines., (Copyright © 2017 American Society for Microbiology.)

Background: Effective leadership is a cornerstone of successful healthcare delivery in resource limited settings throughout the world. However, few programs in Africa prepare healthcare professionals with the leadership skills vital to the success of the healthcare systems in which they work. One such program, the Afya Bora Consortium Fellowship in Global Health Leadership, has been training health professionals since 2011. The purpose of this study was to assess what career changes, if any, the Afya Bora Fellowship's alumni have experienced since completing the fellowship, and to describe those changes., Methods: The Afya Bora Fellowship is a multidisciplinary, one-year training program that teaches health professionals leadership skills through didactic and experiential learning in four African countries. Between January 2011 and June 2013 the consortium trained 42 nurses and doctors. In November 2013, an electronic survey was sent to all alumni to assess their performance in the workplace post-fellowship., Results: Thirty-one (74 %) of 42 alumni completed surveys. Twenty-one (68 %) reported changes to their position at work; of those, sixteen (76 %) believed the change was due to participation in the fellowship. All alumni reported improved performance at work, and cited the application of a wide range of fellowship skills, including leadership, research, communication, and mentoring. Twenty-six (84 %) alumni spearheaded improvements in their workplaces and almost all (97 %) remained in contact with colleagues from the fellowship. Among the respondents there were five publications, nine manuscripts in preparation, and three international conference presentations., Conclusions: Afya Bora alumni overwhelmingly reported that the one year fellowship positively influenced both their work and career trajectory. Training health professionals in leadership skills through didactic modules with the opportunity to apply learned skills at attachment sites in the Afya Bora Fellowship has an impact on performance in the workplace and the potential to improve long-term institutional capacity.

Training health professionals in leadership and management skills is a key component of health systems strengthening in low-resource settings. The importance of evaluating the effectiveness of these programs has received increased attention over the past several years, although such evaluations continue to pose significant challenges. This article presents evaluation data from the pilot year of the Afya Bora Fellowship, an African-based training program to increase the leadership capacity of health professionals. Firstly, we describe the goals of the Afya Bora Fellowship. Then, we present an adaptation of the transtheoretical model for behavior change called the Health Leadership Development Model, as an analytical lens to identify and describe evidence of individual leadership behavior change among training participants during and shortly after the pilot year of the program. The Health Leadership Development Model includes the following: pre-contemplation (status quo), contemplation (testing and internalizing leadership), preparation - (moving toward leadership), action (leadership in action), and maintenance (effecting organizational change). We used data from surveys, in-depth interviews, journal entries and course evaluations as data points to populate the Health Leadership Development Model. In the short term, fellows demonstrated increased leadership development during and shortly after the intervention and reflected the contemplation, preparation and action stages of the Health Leadership Development Model. However, expanded interventions and/or additional time may be needed to support behavior change toward the maintenance stages. We conclude that the Health Leadership Development Model is useful for informing health leadership training design and evaluation to contribute to sustainable health organizational change., (© The Author(s) 2014.)

Interest in global health (GH) among medical students worldwide is measurably increasing. There is a concomitant emphasis on emphasizing globally-relevant health professions education. Through a structured literature review, expert consensus recommendations, and contact with relevant professional organizations, we review the existing state of GH education in US medical schools for which data were available. Several recommendations from professional societies have been developed, along with a renewed emphasis on competencies in global health. The implementation of these recommendations was not observed as being uniform across medical schools, with variation noted in the presence of global health curricula. Recommendations for including GH in medical education are suggested, as well as ways to formalize GH curricula, while providing flexibility for innovation and adaptation.

The Afya Bora Consortium is a partnership of 8 academic health institutions, 4 in Africa and 4 in the United States. The Consortium is developing a Global Health Leadership Fellowship for medical, nursing, and public health professionals, largely drawn from the 4 African partner countries. The fellowship provides trainees with practical skills to prepare them for future positions leading the design, implementation, and evaluation of large, high-impact programs in governmental agencies, nongovernmental organizations, and academic health institutions in their own countries. This article describes a Pilot of the proposed program., (Copyright © 2011 Elsevier Inc. All rights reserved.)

Poliomyelitis has appeared in epidemic form, become endemic on a global scale, and been reduced to near-elimination, all within the span of documented medical history. Epidemics of the disease appeared in the late 19th century in many European countries and North America, following which polio became a global disease with annual epidemics. During the period of its epidemicity, 1900-1950, the age distribution of poliomyelitis cases increased gradually. Beginning in 1955, the creation of poliovirus vaccines led to a stepwise reduction in poliomyelitis, culminating in the unpredicted elimination of wild polioviruses in the United States by 1972. Global expansion of polio immunization resulted in a reduction of paralytic disease from an estimated annual prevaccine level of at least 600,000 cases to fewer than 1,000 cases in 2000. Indigenous wild type 2 poliovirus was eradicated in 1999, but unbroken localized circulation of poliovirus types 1 and 3 continues in 4 countries in Asia and Africa. Current challenges to the final eradication of paralytic poliomyelitis include the continued transmission of wild polioviruses in endemic reservoirs, reinfection of polio-free areas, outbreaks due to circulating vaccine-derived polioviruses, and persistent excretion of vaccine-derived poliovirus by a few vaccinees with B-cell immunodeficiencies. Beyond the current efforts to eradicate the last remaining wild polioviruses, global eradication efforts must safely navigate through an unprecedented series of endgame challenges to assure the permanent cessation of all human poliovirus infections.

Poliomyelitis has long served as a model for studies of viral pathogenesis, but there remain many important gaps in our understanding of this disease. It is the intent of this review to highlight these residual but important questions, in light of a possible future moratorium on research with polioviruses. Salient questions include: (1) What cells in the gastrointestinal tract are initially infected and act as the source of excreted virus? (2) What is the receptor used by mouse-adapted strains of poliovirus and how can some polioviruses use both mouse and primate receptors? (3) What determines species differences in susceptibility of the gastrointestinal tract to polioviruses? Why cannot PVR transgenic mice be infected by the natural enteric route? (4) Why are neuroadapted polioviruses unable to infect nonneural cells? (5) What is the role of postentry blocks in replication as determinants of neurovirulence? (6) What route(s) does poliovirus take to enter the central nervous system and how does it cross the blood-brain barrier? (7) Why does poliovirus preferentially attack lower motor neurons in contrast to many other neuronal types within the central nervous system? (8) Does cellular immunity play any role in recovery from acute infection or in vaccine-induced protection? (9) In which cells does poliovirus persist in patients with gamma-globulin deficiencies? (10) Is there any evidence that poliovirus genomes can persist in immunocompetent hosts? (11) Why has type 2 poliovirus been eradicated while types 1 and 3 have not? (12) Can transmission of vaccine-derived polioviruses be prevented with inactivated poliovirus vaccine? (13) What is the best strategy to control and eliminate vaccine-derived polioviruses?

Perforation is an exceptionally rare complication of duodenal diverticula and often presents with nonspecific symptoms and signs. We present a case of a perforated duodenal diverticulum diagnosed on computed tomography and successfully repaired with a diverticulectomy.

In this review, I use the term "perpetuation" for persistence of a virus in a population, since this is a different phenomenon from persistence of a virus in an infected host. Important variables that influence perpetuation differ in small (<1000 individuals) and large (>10,000) populations: in small populations, two important variables are persistence in individuals, and turnover of the population, while in large populations important variables are transmissibility, generation time, and seasonality. In small populations, viruses such as poliovirus that cause acute infections cannot readily be perpetuated, in contrast to viruses such as hepatitis B virus, that cause persistent infections. However, small animal populations can turnover significantly each year, permitting the perpetuation of some viruses that cause acute infections. Large populations of humans are necessary for the perpetuation of acute viruses; for instance, measles required a population of 500,000 for perpetuation in the pre-measles vaccine era. Furthermore, if an acute virus, such as poliovirus, exhibits marked seasonality in large populations, then it may disappear during the seasonal trough, even in the presence of a large number of susceptible persons. Eradication is the converse of perpetuation and can be used as a definitive approach to the control of a viral disease, as in the instance of smallpox. Therefore, the requirements for perpetuation have significant implications for practical public health goals.

Within the past 4 years, poliomyelitis outbreaks associated with circulating vaccine-derived polioviruses (cVDPVs) have occurred in Hispaniola (2000-01), the Philippines (2001), and Madagascar (2001-02). Retrospective studies have also detected the circulation of endemic cVDPV in Egypt (1988-93) and the likely localized spread of oral poliovirus vaccine (OPV)-derived virus in Belarus (1965-66). Gaps in OPV coverage and the previous eradication of the corresponding serotype of indigenous wild poliovirus were the critical risk factors for all cVDPV outbreaks. The cVDPV outbreaks were stopped by mass immunization campaigns using OPV. To increase sensitivity for detecting vaccine-derived polioviruses (VDPVs), in 2001 the Global Polio Laboratory Network implemented additional testing requirements for all poliovirus isolates under investigation. This approach quickly led to the recognition of the Philippines and Madagascar cVDPV outbreaks, but of no other current outbreaks. The potential risk of cVDPV emergence has increased dramatically in recent years as wild poliovirus circulation has ceased in most of the world. The risk appears highest for the type 2 OPV strain because of its greater tendency to spread to contacts. The emergence of cVDPVs underscores the critical importance of eliminating the last pockets of wild poliovirus circulation, maintaining universally high levels of polio vaccine coverage, stopping OPV use as soon as it is safely possible to do so, and continuing sensitive poliovirus surveillance into the foreseeable future. Particular attention must be given to areas where the risks for wild poliovirus circulation have been highest, and where the highest rates of polio vaccine coverage must be maintained to suppress cVDPV emergence.

Study Objectives: A decision instrument based on 5 clinical criteria has been shown to be highly sensitive in selecting patients who require cervical spine imaging after blunt trauma, while simultaneously reducing overall imaging. We examine the performance of this instrument in the elderly and explore some of the common features of geriatric cervical spine injury (CSI)., Methods: The National Emergency X-radiography Utilization Study (NEXUS) was a prospective, observational, multicenter study conducted at 21 geographically diverse centers. We analyzed the performance of the NEXUS decision instrument among patients at least 65 years of age., Results: The study group consisted of 2,943 (8.6%) geriatric patients, representing 8.6% of the entire NEXUS sample. The rate of CSI was twice as great in these patients as it was in nongeriatric patients (4.59% versus 2.19%). Odontoid fractures were particularly common in geriatric patients, accounting for 20% of geriatric fractures compared with 5% of nongeriatric fractures. The frequency of patients meeting NEXUS criteria was similar in the 2 groups, with 14% of geriatric patients and 12.5% of nongeriatric patient classified as low risk. CSI occurred in only 2 low-risk geriatric patients, and these patients' injuries met our preset definition of a clinically insignificant injury. The sensitivity of the NEXUS decision instrument for clinically significant injury in the geriatric group was therefore 100% (95% confidence interval 97.1% to 100%)., Conclusion: The prevalence of CSI, and especially odontoid fracture, is relatively increased among geriatric patients with blunt trauma. The NEXUS decision instrument can be applied safely to these patients, with an expected reduction in cervical imaging comparable with that achieved in nongeriatric patients.

Activation of extracellular signal-regulated kinases (ERK) is crucial for many neural functions, including learning, memory, and synaptic plasticity. As muscarinic acetylcholine receptors (mAChR) modulate many of the same higher brain functions as ERK, we examined mAChR-mediated ERK activation in mouse hippocampal slices. The cholinergic agonist carbachol caused an atropine-sensitive ERK activation in the dendrites and somata CA1 pyramidal neurons. To determine the responsible mAChR subtype, we combined pharmacologic and genetic approaches. Pretreatment with M1 antagonists inhibited ERK activation. Furthermore, mAChR-induced ERK activation was absent in slices from M1 knockout mice. ERK activation was normal in slices derived from other mAChR subtype knockouts (M2, M3, and M4), although these other subtypes are expressed in many of the same neurons. Thus, we demonstrate divergent functions for the different mAChR subtypes. We conclude that M1 is responsible for mAChR-mediated ERK activation, providing a mechanism by which M1 may modulate learning and memory.

Muscarinic acetylcholine receptors (mAChR) in the central nervous system are involved in learning and memory, epileptic seizures, and processing the amyloid precursor protein. The M(1) receptor is the predominant mAChR subtype in the cortex and hippocampus. Although the five mAChR fall into two broad functional groups, all five subtypes, when expressed in recombinant systems, can activate the mitogen-activated protein kinase (MAPK) pathway. The MAPK pathway has been implicated in learning and memory, amyloid protein processing, and neuronal plasticity. We used M(1) knock-out mice to determine the role of this receptor subtype in signal transduction in the mouse forebrain. In primary cortical cultures from mice lacking the M(1) mAChR, agonist-stimulated phosphoinositide hydrolysis was reduced by more than 60% compared with cultures from wild type mice. Although muscarinic agonists induced robust activation of MAPK in cortical cultures from wild type mice, mAChR-mediated activation of MAPK was virtually absent in cultures from M(1)-deficient mice. These results indicate that the M(1) mAChR is the major subtype that mediates activation of phospholipase C and MAPK in mouse forebrain.

Muscarinic receptors have been implicated in the regulation of cognition and psychosis based on pharmacological evidence from pre-clinical and clinical studies. Muscarinic agonists have shown promise in the clinic in improving cognition and reducing psychotic episodes in Alzheimer's patients. However, lack of selective muscarinic ligands has limited their use due to troublesome side effects observed at higher doses. Without selective ligands, it has been difficult to assign a specific muscarinic receptor subtype to these high order mental processes. Recent development of muscarinic receptor knockout mice has provided additional tools to investigate cognition and psychosis in behavioral assays and to determine the receptor subtypes associated with parasympathomimetic physiology. Biochemical studies indicate that the M1 receptor plays a significant role in regulating G alpha q-mediated signal transduction in the hippocampus and cortex. Behavioral studies suggest that the M4 receptor is involved in movement regulation and prepulse inhibition of the startle reflex, a measure of attention. These findings support a role for the development of M1 and M4 receptor agonists for diseases in which symptoms include cognitive impairment and psychotic behaviors.

Cholinergic stimuli are potent regulators of the circadian clock in the hypothalamic suprachiasmatic nucleus (SCN). Using a brain slice model, we have found that the SCN clock is subject to muscarinic regulation, a sensitivity expressed only during the night of the clock's 24-h cycle. Pharmacological and signal transduction characteristics are compatible with a response mediated by an M1-like receptor. Molecular manipulation of muscarinic receptors will provide important insights as to the receptor subtype(s) regulating circadian rhythms.

We used gene targeting to generate mice lacking the M1 muscarinic acetylcholine receptor. These mice exhibit a decreased susceptibility to pilocarpine-induced seizures, loss of regulation of M-current potassium channel activity and of a specific calcium channel pathway in sympathetic neurons, a loss of the positive chronotropic and inotropic responses to the novel muscarinic agonist McN-A-343, and impaired learning in a hippocampal-dependent test of spatial memory.

Many different G protein-coupled receptors modulate the activity of Ca2+ and K+ channels in a variety of neuronal types. There are five known subtypes (M1-M5) of muscarinic acetylcholine receptors. Knockout mice lacking the M1, M2, or M4 subtypes are studied to determine which receptors mediate modulation of voltage-gated Ca2+ channels in mouse sympathetic neurons. In these cells, muscarinic agonists modulate N- and L-type Ca2+ channels and the M-type K+ channel through two distinct, G-protein mediated pathways. The fast and voltage-dependent pathway is lacking in the M2 receptor knockout mice. The slow and voltage-independent pathway is absent in the M1 receptor knockout mice. Neither pathway is affected in the M4 receptor knockout mice. Muscarinic modulation of the M current is absent in the M1 receptor knockout mice, and can be reconstituted in a heterologous expression system using cloned channels and M1 receptors. Our results using knockout mice are compared with pharmacological data in the rat.

Muscarinic acetylcholine receptors (mAChRs) can be differentially localized in polarized cells. To identify potential sorting signals that mediate mAChR targeting, we examined the sorting of mAChRs in Madin-Darby canine kidney cells, a widely used model system. Expression of FLAG-tagged mAChRs in polarized Madin-Darby canine kidney cells demonstrated that the M(2) subtype is sorted apically, whereas M(3) is targeted basolaterally. Expression of M(2)/M(3) receptor chimeras revealed that a 21-residue sequence, Ser(271)-Ser(291), from the M(3) third intracellular loop contains a basolateral sorting signal. Substitution of sequences containing the M(3) sorting signal into the homologous regions of M(2) was sufficient to confer basolateral localization to this apical receptor. Sequences containing the M(3) sorting signal also conferred basolateral targeting to M(2) when added to either the third intracellular loop or the C-terminal cytoplasmic tail. Furthermore, addition of a sequence containing the M(3) basolateral sorting signal to the cytoplasmic tail of the interleukin-2 receptor alpha-chain caused significant basolateral targeting of this heterologous apical protein. The results indicate that the M(3) basolateral sorting signal is dominant over apical signals in M(2) and acts in a position-independent manner. The M(3) sorting signal represents a novel basolateral targeting motif for G protein-coupled receptors.

Muscarinic acetylcholine receptors (mAChRs) play an important role in signal processing in the retina. We have used subtype-specific antibodies to identify the changes in the localization of mAChR expression during embryonic development of the retina in vivo and their relationship to the changes in mAChRs in retinal cells in culture. We have demonstrated previously that treatment of fresh retinal cultures with conditioned media from mature retinal cultures specifically induces expression of the M(2) mAChR (McKinnon et al., 1998). We show that the M(2)-inducing activity, which we tentatively have called MARIA (muscarinic acetylcholine receptor-inducing activity) is produced by Müller glial cells in culture, because significant activity can be found in media conditioned by essentially neuron-free cultures of Müller glia, as well as by a Müller glial cell line but not several neuroblastoma cell lines. We also demonstrate that the appearance of the M(2) receptor in vivo occurs concomitantly with the appearance of significant numbers of Müller glial cells in the developing retina. Furthermore, the administration of crude or partially purified preparations of MARIA to developing chick embryos in ovo induces precocious expression of M(2) mAChRs in the appropriate cell types in the retina. These results show that a factor secreted by cultured retinal Müller glia can regulate M(2) mAChR expression in vivo and in vitro and suggest that the secretion of MARIA by Müller glia in vivo may be responsible for the normal induction of M(2) mAChR expression during embryonic development.

The Office of AIDS Research (OAR) at the National Institutes of Health (NIH) is responsible for the coordination of AIDS research. In June 1999, the OAR, in conjunction with the NIH Institutes and Centers, initiated a review of NIH-sponsored pediatric AIDS research. This article discusses a number of important priorities for future clinical research in NIH-sponsored pediatric AIDS in both developed and developing countries. These have the potential to significantly prevent perinatal transmission, reduce adolescent infections, and impact treatment of pediatric infections.

Over the last 12 years, many human immunodeficiency virus (HIV) vaccine candidates have been tried in humans, with disappointing results. In particular, recombinant envelope proteins have failed to elicit strong cellular immune responses or neutralizing antibody against many wild-type isolates of HIV-1. Attenuated strains of simian immunodeficiency virus (SIV), although capable of protecting against virulent strains of SIV, often retain residual pathogenicity. These difficulties suggest that it will be necessary to address a number of biological questions that underpin the rational development of an AIDS vaccine: (1) Will natural infection with HIV protect against superinfection? (2) Is partial protection induced by an HIV vaccine adequate to prevent AIDS? (3) What are the immune correlates of protection for an AIDS vaccine? (4) Will a monotypic HIV-1 vaccine confer cross-clade immunity? (5) Is mucosal immunity important for an effective AIDS vaccine? (6) Is there a rationale for therapeutic immunization? Ongoing research that is addressing these questions should lead to the formulation of a safe and effective AIDS vaccine.

Endocytosis of agonist-activated G protein-coupled receptors (GPCRs) is required for both resensitization and recycling to the cell surface as well as lysosomal degradation. Thus, this process is crucial for regulation of receptor signaling and cellular responsiveness. Although many GPCRs internalize into clathrin-coated vesicles in a dynamin-dependent manner, some receptors, including the M(2) muscarinic acetylcholine receptor (mAChR), can also exhibit dynamin-independent internalization. We have identified five amino acids, located in the sixth and seventh transmembrane domains and the third intracellular loop, that are essential for agonist-induced M(2) mAChR internalization via a dynamin-independent mechanism in JEG-3 choriocarcinoma cells. Substitution of these residues into the M(1) mAChR, which does not internalize in these cells, is sufficient for conversion to the internalization-competent M(2) mAChR phenotype, whereas removal of these residues from the M(2) mAChR blocks internalization. Cotransfection of a dominant-negative isoform of dynamin has no effect on M(2) mAChR internalization. An internalization-incompetent M(2) mutant that lacks a subset of the necessary residues can still internalize via a G protein-coupled receptor kinase-2 and beta-arrestin-dependent pathway. Furthermore, internalization is independent of the signal transduction pathway that is activated. These results identify a novel motif that specifies structural requirements for subtype-specific dynamin-independent internalization of a GPCR.

The receptor for leukemia inhibitory factor (LIF) consists of two polypeptides, the LIF receptor and gp130. Agonist stimulation has been shown previously to cause phosphorylation of gp130 on serine, threonine, and tyrosine residues. We found that gp130 fusion proteins were phosphorylated exclusively on Ser-782 by LIF- and growth factor-stimulated 3T3-L1 cell extracts. Ser-780 was required for phosphorylation of Ser-782 but was not itself phosphorylated. Ser-782 is located immediately N-terminal to the di-leucine motif of gp130, which regulates internalization of the receptor. Transient expression of chimeric granulocyte colony-stimulating factor receptor (G-CSFR)-gp130(S782A) receptors resulted in increased cell surface expression in COS-7 cells and increased ability to induce vasoactive intestinal peptide gene expression in IMR-32 neuroblastoma cells when compared with expression of chimeric receptors containing wild-type gp130 cytoplasmic domains. These results identify Ser-782 as the major phosphorylated serine residue in human gp130 and indicate that this site regulates cell surface expression of the receptor polypeptide.

The neurally active cytokine leukemia inhibitory factor (LIF) signals through a bipartite receptor complex composed of LIF receptor alpha (LIFR) and gp130. gp130 and LIFR contain consensus binding motifs for the protein tyrosine phosphatase SHP-2 surrounding tyrosines 118 and 115 (Y118 and Y115) of their cytoplasmic domains, respectively. These sites are necessary for maximal activation of mitogen-activated protein kinase (MAPK). Coexpression of catalytically inactive, but not wild-type, SHP-2 reduced LIFR- and gp130-mediated activation of MAPK up to 75%. Conversely, coexpression of the wild-type, but not catalytically inactive, SHP-1, a related phosphatase, reduced activity up to 80%, demonstrating that SHP-2 and SHP-1 have opposing effects on the MAPK pathway. Mutation of Y115 of the cytoplasmic domain of LIFR eliminates receptor-mediated tyrosine phosphorylation of SHP-2. In contrast, SHP-1 association with gp130 and LIFR is constitutive and independent of Y118 and Y115, respectively. SHP-1 has a positive regulatory role on LIF-stimulated vasoactive intestinal peptide (VIP) reporter gene expression in neuronal cells, whereas the effect of SHP-2 is negative. Furthermore, LIF-stimulated MAPK activation negatively regulates this VIP reporter gene induction. SHP-2 also negatively regulates LIF-dependent expression of choline acetyltransferase, but this regulation could be dissociated from its effects on MAPK activation. These data indicate that SHP-1 and SHP-2 are important regulators of LIF-dependent neuronal gene expression via both MAPK-dependent and -independent pathways.

The chick is a widely used system for study of the actions of muscarinic acetylcholine receptors in the cardiovascular, visual, and nervous systems. We report the isolation and functional analysis of the gene encoding the chick M5 muscarinic receptor. RT-PCR analysis indicates that the M5 receptor is expressed at low levels in embryonic chick brain and heart. When expressed in stably transfected Chinese hamster ovary cells, the M5 receptor exhibits high-affinity binding to muscarinic antagonists and mediates robust activation of phospholipase C activity.

Activation of muscarinic acetylcholine (ACh) receptors (mAChRs) increases excitability of pyramidal cells by inhibiting several K+ conductances, including the after-hyperpolarization current (Iahp), the M-current (Im), and a leak K+ conductance (Ileak). Based on pharmacological evidence and the abundant localization of M1 receptors in pyramidal cells, it has been assumed that the M1 receptor is responsible for mediating these effects. However, given the poor selectivity of the pharmacological agents used to characterize these mAChR responses, rigorous characterization of the receptor subtypes that mediate these actions has not been possible. Surprisingly, patch clamp recording from CA1 pyramidal cells in M1 knockout mice revealed no significant difference in the degree of inhibition of Iahp, Im, or Ileak by the mAChR agonist, carbachol (CCh), as compared with wildtype controls. In addition, the M1-toxin was not able to block CCh's inhibition of the Iahp, Im, or Ileak These data demonstrate that the M1 receptor is not involved in increasing CA1 pyramidal cell excitability by mediating ACh effects on these K+ conductances.

We have characterized the muscarinic ACh receptors (mAChRs) expressed in Madin- Darby canine kidney (MDCK) strain II epithelial cells. Binding studies with the membrane-impermeable antagonist N-[(3)H]methylscopolamine demonstrated that mAChRs are approximately 2.5 times more abundant on the basolateral than on the apical surface. Apical, but not basolateral, mAChRs inhibited forskolin-stimulated adenylyl cyclase activity in response to the agonist carbachol. Neither apical nor basolateral mAChRs exhibited detectable carbachol-stimulated phospholipase C activity. Carbachol application to the apical or the basolateral membrane resulted in a threefold increase in intracellular Ca(2+) concentration, which was completely inhibited by pertussis toxin on the apical side and partially inhibited on the basolateral side. RT-PCR analysis showed that MDCK cells express the M(4) and M(5) receptor mRNAs. These data suggest that M(4) receptors reside on the apical and basolateral membranes of polarized MDCK strain II cells and that the M(5) receptor may reside in the basolateral membrane of a subset of cells.

There are five known subtypes of muscarinic receptors (M(1)-M(5)). We have used knockout mice lacking the M(1), M(2), or M(4) receptors to determine which subtypes mediate modulation of voltage-gated Ca(2+) channels in mouse sympathetic neurons. Muscarinic agonists modulate N- and L-type Ca(2+) channels in these neurons through two distinct G-protein-mediated mechanisms. One pathway is fast and membrane-delimited and inhibits N- and P/Q-type channels by shifting their activation to more depolarized potentials. The other is slow and voltage-independent and uses a diffusible cytoplasmic messenger to inhibit both Ca(2+) channel types. Using patch-clamp methods on acutely dissociated sympathetic neurons, we isolated each pathway by pharmacological and kinetic means and found that each one is nearly absent in a particular knockout mouse. The fast and voltage-dependent pathway is lacking in the M(2) receptor knockout mice; the slow and voltage-independent pathway is absent from the M(1) receptor knockout mice; and neither pathway is affected in the M(4) receptor knockout mice. The knockout effects are clean and are apparently not accompanied by compensatory changes in other muscarinic receptors.

Over the last 10 years, about 20 human immunodeficiency virus (HIV) vaccine candidates have been tried in humans, with disappointing results as gauged by limited immune responses or protection against infection. These difficulties suggest that a new strategy is needed to test systematically new vaccine candidates. That opportunity is now afforded by nonhuman primate models with SIV, which have been shown to provide an excellent mirror of HIV infection in humans. The recent introduction of SHIVs, chimeric viruses that carry the HIV envelope and are able to infect and cause AIDS in monkeys, also has added an important additional research tool. These models can be used to address a series of questions, including the following: (1) Can protection be provided by partial immunity or is sterilizing immunity required? (2) What are the immune parameters that best predict protection against a potentially pathogenic challenge? (3) What role does mucosal immunity play and can it be induced by practical modes of immunization? (4) Can an attenuated virus be selected that is both protective and safe? An orderly strategy for the evaluation of vaccine candidates could be adopted that would involve several phases: (a) the selection of a limited set of challenge models, ranging from very severe to mild and requiring consideration of primate species, age, route of infection, and challenge viruses; (b) the assessment of candidate vaccines using comparable virus challenges; and (c) accelerated testing in humans of any candidate vaccines that have met a 'proof of efficacy' in primates.

1. Leukemia inhibitory factor action is mediated by a heterodimeric receptor consisting of two subunits, gp130 and the low-affinity leukemia inhibitory factor receptor (LIFR). 2. We used chimeric receptors containing the intracellular domain of either the LIFR or gp130 to identify regions of the receptors required for induction of the m2 muscarinic acetylcholine receptor gene in IMR-32 and SN56 neuronal cells. 3. While chimeric receptors containing the intracellular domain of gp130 were able to induce transcription from both the m2 and the vasoactive intestinal peptide (VIP) gene promoters, chimeric receptors containing the intracellular domain of the LIFR were incapable of mediating induction of the m2 gene despite being able to induce VIP transcription. 4. Deletion and mutagenesis studies identified two tyrosines, Y905 and Y915, which were required for maximal induction of the m2 and VIP genes. 5. Because Y905 and Y915 are reported to be the only tyrosine residues in gp130 that bind Stat1, these results suggest that this transcription factor plays a key role in the induction of transcription of both the m2 and the VIP genes.

Over the past decade, a substantial research investment has generated a vast body of knowledge relevant to the development of an effective AIDS vaccine. Furthermore, studies in nonhuman primates have demonstrated that a number of candidate immunogens can confer a significant degree of protection against a potentially pathogenic SIV or SHIV. Currently, there exists a robust program that supports discovery of new HIV immunogens and a proven successful program for collaborative human trials of promising vaccine candidates. However, we believe that there is a gap between discovery and clinical trials. An orderly process for screening of candidate immunogens prior to human trials would facilitate the vaccine development program. We suggest that nonhuman primates can fill this strategic gap and could accelerate vaccine development. Recognizing that there is considerable controversy about the potential usefulness of the primate models, we have attempted to set forth the relevant practical and biological issues as a series of questions for discussion. The most important biological problem is the absence of a single immune response correlate that will predict vaccine efficacy. Data from primate models indicate that such a single predictive correlate may not exist. In turn, this argues for a vaccine screening protocol that includes a pathogenic virus challenge, an approach only available in the nonhuman primate model. The further assumption is that nonprimate models can be used to predict the relative protective efficacy of diverse immunization protocols, a hypothesis that can only be tested by comparative studies yet to be conducted. A 'standard' set of virus challenges must be selected for comparison of different immunization protocols, and this effort has been initiated. At the practical level, it appears that the large number of candidate immunogens now being developed requires a screening process of the kind proposed, since it would not be practical to test all new immunogens and protocols in humans. In conclusion, it appears timely to crystallize an orderly process for the discovery, screening, and human testing of candidate AIDS vaccines, understanding that a vaccine development program should not be conducted at the expense of investigator-initiated research in the diverse disciplines that support rational vaccine design and development. The components of a rational process of vaccine development are well established and only remain to be welded into one coherent program.

We have investigated the molecular mechanisms involved in the regulation of muscarinic acetylcholine receptor gene expression and localization and generated knockout mice to study the role of the M1 muscarinic receptor in vivo. We have used the MDCK cell system to demonstrate that different subtypes of mAChR can be targeted to different regions of polarized cells. We have also examined the developmental regulation of mAChR expression in the chick retina. Early in development, the M4 receptor is the predominant mAChR while the levels of the M2 and M3 receptors increase later in development. The level of M2 receptor is also initially very low in retinal cultures and undergoes a dramatic increase over several days in vitro. The level of M2 receptor can be increased by a potentially novel, developmentally regulated, secreted factor produced by retinal cells. The promoter for the chick M2 receptor gene has been isolated and shown to contain a site for GATA-family transcription factors which is required for high level cardiac expression. The M2 promoter also contains sites which mediate induction of transcription in neural cells by neurally active cytokines. We have generated knockout mice lacking the M1 receptor and shown that these mice do not exhibit pilocarpine-induced seizures and muscarinic agonist-induced suppression of the M-current potassium channel in sympathetic neurons.

New viral infections of humans appear to be emerging at an increasing tempo, probably due to technological developments and societal changes that have enhanced the ability of viruses to invade and spread within the human population. Emergence can be due to several discrete phenomena. Existing viruses of humans continue to be isolated, identified, followed by the description of new nosological entities. An increase in the ratio of cases:infections for ubiquitous viruses may lead to the emergence of new epidemics, associated either with the altered host susceptibility or increased viral virulence. Finally, viruses may invade populations from which they have disappeared or may cross the species barrier to invade new species. When a virus invades a new species it usually fails to spread from individual to individual. However, on rare occasions a virus adapts to a new species, usually involving mutations in the viral genome that alter the cellular host range. In such instances, if circumstances favor transmission, a pandemic may occur. For a new virus to endanger blood products, several criteria must be met. First the virus must be able to spread widely in the human population; second, it must cause a persistent plasma viraemia of moderate to high titre (although there are exceptions); and third, virus carriers must be asymptomatic. This set of conditions has only occurred once in the recorded history of human virology, with human immunodeficiency virus. It would probably be difficult to predict another invasion of the human population with a new virus, at least from studies in comparative virology. Probably the best deterrent strategy to facilitate the early recognition of any such hypothetical rare occurrence is the identification and control of all viruses that presently endanger the blood supply, supplemented by an active surveillance system to identify post-transfusion illnesses of any kind., (Copyright 1998 The International Association of Biological Standardization)