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Abstract. Background:. Despite the recent emphasis on promoting international collaborations within orthopaedic surgery, criteria for determining the strengths of such partnerships has not been established. The purpose of this study was to evaluate orthopaedic experts' perceptions of the most valuable characteristics of international academic partnerships. Methods:. This study was conducted using a modified Delphi methodology. Experts were identified through the Consortium of Orthopaedic Academic Traumatologists (COACT). Responses were collected from February to September 2022. Three rounds of surveys listing possible topics on a 5-point Likert scale were used to develop consensus among a group of experts. Consensus criteria for topic inclusion in the final scale was determined as a rating of “strongly agree” or “agree” by ≥70% of the participants in the third survey. Results:. The Round 1 survey was distributed to 96 invited participants within the COACT network, of which 50 experts (52.1%) completed the first survey. Consensus was reached on 54 topics organized into the following 5 categories: Research, Advocacy/Leadership, Training/Surgical Skills, Education/Knowledge Exchange, and Sustainability and Safety (RATES Criteria). Conclusions:. Determining the most valuable characteristics of successful international academic partnerships can lead to more sustainable, mutually beneficial collaborations. The criteria identified in this study can provide the foundation for developing new partnerships and assessing existing ones.

Category: Bunion Introduction/Purpose: Proximal first metatarsal crescentic osteotomies are an effective means for correction of moderate to severe hallux valgus deformities. The originally described fixation construct included an intramedullary screw and a Kirschner wire which crossed the joint and required removal at 6 weeks. Elevation malunion of the first ray was also frequently noted postoperatively. The purpose of this study was to evaluate the outcomes of utilizing a low-profile titanium plate and screw construct for rigid fixation of proximal crescentic osteotomies. Methods: There were 53 patients (60 feet, 7 bilateral) with hallux valgus deformities enrolled in the study. They were all treated operatively with a proximal crescentic osteotomy and distal soft tissue correction with or without an Akin osteotomy. The crescentic osteotomy was fixed with a low-profile titanium plate and screws. Postoperatively patients were assessed at 3 months, 6 months and 1 year. Outcomes assessed included the need for hardware removal, change in elevatus of the first ray, as well as pre- and post-op VAS pain scores, radiographic evaluation, AOFAS score, MTP joint range of motion, and complications. Results: Of the 60 hallux valgus cases enrolled, 56 have completed their final follow-up (93%). At 1 year 55/56 patients had achieved radiographic union of their osteotomy. Nine patients had their hardware removed (16%). Range of motion at the 1st MTP joint decreased from 76.5 to 59.6 degrees. Hallux valgus angle improved from a mean of 28.8 to 9.6 degrees. The mean 1-2 intermetatarsal angle decreased from 14.1 to 6.4 degrees. Elevatus of the first ray increased from a mean of 2.5 mm pre-op to 3.2 mm (

Category: Midfoot/Forefoot Introduction/Purpose: Midfoot arthrodesis remains a technical challenge. Little is known of the required magnitude of compression in order to obtain fusion. Multiple techniques have been reported, reflecting the difficulty of achieving a good result. These methods include an in situ bone graft dowel technique, dorsal staple, Kirschner wire, trans articular lag screw, and screw and plate fixation. More recently, dorsal hybrid plating, and slot graft inlay arthrodesis have been described. The purpose of this study is to describe the results of a dorsal fixed-angle locking compression plate in the setting of multiple-joint midfoot arthrodeses. Methods: A retrospective study was performed to identify 62 consecutive patients who underwent midfoot arthrodeses from June 2009 to May 2016. A total of 184 joints were spanned by dorsal fixed angle locking compression plates. The medical risk factors, etiology of arthritis, body mass index, time to union, visual analog pain scores (recorded preoperatively and postoperatively), and post-operative complications were evaluated. Patients were followed for one year. Radiographs were read by two fellowship-trained surgeons to determine the time to fusion. If union was indeterminate, a computed tomography scan was obtained, with the presence of 50% or greater bridging bone as the definition of fusion. Results: Of the joints spanned, 156 fused (83%). The average time to fusion was 19.6 weeks (Standard Deviation 21 weeks). Complications included persistent numbness (10), wound infection (2), and deep venous thrombus (1). The average VAS score diminished from 5.9 preoperatively, to 1.7 at week 6, 1.9 at week 12, 2.6 at month 6, and 3.1 at one year. Conclusion: Despite the difficulty of midfoot arthrodesis procedures in obtaining solid fusion, the dorsal fixed angle locking compression plate demonstrates a union rate, time to fusion, and complication rate that is comparable with the existing literature. The results of this study also indicate room for improvement in the design of advanced plating systems, which could incorporate more uniform joint compression combined with biologic augmentation in the hope of achieving improved radiographic and clinical results.

Background: The burden of complex orthopaedic trauma in low-income countries is compounded by insufficient plastic surgeons to assist in management of soft tissue injuries. To address this global health-care disparity, we created a soft tissue management course to train orthopaedic surgeons from low-income countries in flap reconstruction. Methods: The Institute for Global Orthopedics & Traumatology hosts a 3-day course to teach orthopaedic surgeons from low-income and middle-income countries flaps using cadaver dissection and didactic lectures. Precourse and postcourse assessments were used to evaluate the course's effect. Findings: In 4 years, 156 surgeons have attended the course from more than 25 different countries. Of 48 participants from the 2010 course, 90% indicated that soft tissue management training would be useful for upper extremity trauma cases and 96% for lower extremity trauma cases. A 1-year postcourse use survey was sent to all the surgeons attending the 2012 course, with 32 of 44 surgeons completing the survey. The respondents collectively undertook 594 flaps with 554 reported as successful (93•3%). Of the successful flaps, 116 flaps were believed to have prevented a subsequent amputation. 31 (97%) of 32 surgeons disseminated information to either colleagues or residents, and through dissemination of information a further 28 surgeons are now undertaking flaps. Interpretation: The skills and knowledge gained at this course by orthopaedic surgeons from low-income countries were recorded to be quickly and extensively used in their countries by our 1-year postcourse survey. This course represents a unique collaboration with physicians in low-income countries that might have the ability to provide a sustainable effect in addressing global health care disparities. Funding: None.

Background: The amount of research utilizing health information has increased dramatically over the last ten years. Many institutions have extensive biobank holdings collected over a number of years for clinical and teaching purposes, but are uncertain as to the proper circumstances in which to permit research uses of these samples. Research Ethics Boards (REBs) in Canada and elsewhere in the world are grappling with these issues, but lack clear guidance regarding their role in the creation of and access to registries and biobanks.Methods: Chairs of 34 REBS and/or REB Administrators affiliated with Faculties of Medicine in Canadian universities were interviewed. Interviews consisted of structured questions dealing with diabetes-related scenarios, with open-ended responses and probing for rationales. The two scenarios involved the development of a diabetes registry using clinical encounter data across several physicians' practices, and the addition of biological samples to the registry to create a biobank.Results: There was a wide range of responses given for the questions raised in the scenarios, indicating a lack of clarity about the role of REBs in registries and biobanks. With respect to the creation of a registry, a minority of sites felt that consent was not required for the information to be entered into the registry. Whether patient consent was required for information to be entered into the registry and the duration for which the consent would be operative differed across sites. With respect to the creation of a biobank linked to the registry, a majority of sites viewed biobank information as qualitatively different from other types of personal health information. All respondents agreed that patient consent was needed for blood samples to be placed in the biobank but the duration of consent again varied.Conclusion: Participants were more attuned to issues surrounding biobanks as compared to registries and demonstrated a higher level of concern regarding biobanks. As registries and biobanks expand, there is a need for critical analysis of suitable roles for REBs and subsequent guidance on these topics. The authors conclude by recommending REB participation in the creation of registries and biobanks and the eventual drafting of comprehensive legislation. [ABSTRACT FROM AUTHOR]

This paper provides a description of the role of the clinical ethicist as it is generally experienced in Canada. It examines the activities of Canadian ethicists working in healthcare institutions and the way in which their work incorporates more than ethics case consultation. The Canadian Bioethics Society established a "Taskforce on Working Conditions for Bioethics" (hereafter referred to as the Taskforce), to make recommendations on a number of issues affecting ethicists and to develop a model role description. This essay carefully assesses this model role description.

Nerve growth factor (NGF) is produced as a precursor called pro-nerve growth factor (proNGF), which is secreted by many tissues and is the predominant form of NGF in the central nervous system. In Alzheimer disease brain, cholinergic neurons degenerate and can no longer transport NGF as efficiently, leading to an increase in untransported NGF in the target tissue. The protein that accumulates in the target tissue is proNGF, not the mature form. The role of this precursor is controversial, and both neurotrophic and apoptotic activities have been reported for recombinant proNGFs. Differences in the protein structures, protein expression systems, methods used for protein purification, and methods used for bioassay may affect the activity of these proteins. Here, we show that proNGF is neurotrophic regardless of mutations or tags, and no matter how it is purified or in which system it is expressed. However, although proNGF is neurotrophic under our assay conditions for primary sympathetic neurons and for pheochromocytoma (PC12) cells, it is apoptotic for unprimed PC12 cells when they are deprived of serum. The ratio of tropomyosin-related kinase A to p75 neurotrophin receptor is low in unprimed PC12 cells compared with primed PC12 cells and sympathetic neurons, altering the balance of proNGF-induced signaling to favor apoptosis. We conclude that the relative level of proNGF receptors determines whether this precursor exhibits neurotrophic or apoptotic activity.

Introduction: Variation across research ethics boards (REBs) in conditions placed on access to medical records for research purposes raises concerns around negative impacts on research quality and on human subject protection, including privacy., Aim: To study variation in REB consent requirements for retrospective chart review and who may have access to the medical record for data abstraction., Methods: Thirty 90-min face-to-face interviews were conducted with REB chairs and administrators affiliated with faculties of medicine in Canadian universities, using structured questions around a case study with open-ended responses. Interviews were recorded, transcribed and coded manually., Results: Fourteen sites (47%) required individual patient consent for the study to proceed as proposed. Three (10%) indicated that their response would depend on how potentially identifying variables would be managed. Eleven sites (38%) did not require consent. Two (7%) suggested a notification and opt-out process. Most stated that consent would be required if identifiable information was being abstracted from the record. Among those not requiring consent, there was substantial variation in recognising that the abstracted information could potentially indirectly re-identify individuals. Concern over access to medical records by an outside individual was also associated with requirement for consent. Eighteen sites (60%) required full committee review. Sixteen (53%) allowed an external research assistant to abstract information from the health record., Conclusions: Large variation was found across sites in the requirement for consent for research involving access to medical records. REBs need training in best practices for protecting privacy and confidentiality in health research. A forum for REB chairs to confidentially share concerns and decisions about specific studies could also reduce variation in decisions.

Nerve growth factor (NGF) promotes neuronal survival and differentiation and stimulates neurite outgrowth. NGF is synthesized as a precursor, proNGF, which undergoes post-translational processing to generate mature beta-NGF. It has been assumed that, in vivo, NGF is largely processed into the mature form and that mature NGF accounts for the biological activity. However, we recently showed that proNGF is abundant in CNS tissues whereas mature NGF is undetectable, suggesting that proNGF has biological functions beyond its role as a precursor. To determine whether proNGF exhibits biological activity, we mutagenized the precursor-processing site and expressed unprocessed, cleavage-resistant proNGF protein in insect cells. Survival and neurite outgrowth assays on murine superior cervical ganglion neurons and PC12 cells indicated that proNGF exhibits neurotrophic activity similar to mature 2.5S NGF, but is approximately fivefold less active. ProNGF binds to the high-affinity receptor, TrkA, as determined by cross-linking to PC12 cells, and is also slightly less active than mature NGF in promoting phosphorylation of TrkA and its downstream signaling effectors, Erk1/2, in PC12 and NIH3T3-TrkA cells. These data, coupled with our previous report that proNGF is the major form of NGF in the CNS, suggest that proNGF could be responsible for much of the biological activity normally attributed to mature NGF in vivo.

Nerve growth factor (NGF) acts on various classes of central and peripheral neurons to promote cell survival, stimulate neurite outgrowth and modulate differentiation. NGF is synthesized as a precursor, proNGF, which undergoes processing to generate mature NGF. It has been assumed, based on studies in the mouse submandibular gland, that NGF in vivo is largely mature NGF, and that mature NGF accounts for the molecule's biological activity. However, recently we have shown that proNGF is abundant in central nervous system tissues whereas mature NGF is undetectable, suggesting that proNGF may have a function distinct from its role as a precursor. A recent report that proNGF has apoptotic activity contrasts with other data demonstrating that proNGF has neurotrophic activity. This chapter will review the structure and processing of NGF and what is known about the biological activity of proNGF. Possible reasons for the discrepancies in recent reports are discussed.

Phaeochromocytoma PC12 cells treated with nerve growth factor (NGF) differentiate into a neuronal phenotype. Here we compare the uptake of transferrin-bound and non-transferrin-bound iron in NGF-treated (neuronal phenotype) and control (proliferating) PC12 cells. The non-transferrin-bound iron uptake was greater in the NGF-treated cells than in the control, independently of the uptake time, the iron-chelating agents used, the oxidation state of iron (Fe(2+) or Fe(3+)) and the iron concentration tested. The NGF-treated cells expressed L-type and N-type voltage-operated Ca(2+) channels. Nitrendipine (an L-type inhibitor) and possibly omega-conotoxin (an N-type inhibitor) inhibited the iron uptake by 20%. Thapsigargin inhibits the endoplasmic reticulum Ca(2+) pump and allowed Mn(2+) entry into cells. Preincubating PC12 cells with thapsigargin increased the iron uptake. The rate of transferrin-bound iron uptake was less than 1% of the non-transferrin-bound iron uptake and the maximum transferrin-bound iron uptake was also very low. We conclude that an increase in the iron uptake by multiple pathways accompanies the transition of PC12 cells from the proliferating to the neuronal phenotype.

Nerve growth factor (NGF) is important for regulation, differentiation, and survival of peripheral and central nervous system neurons, including basal forebrain cholinergic neurons (BFCN) which degenerate in Alzheimer's disease (AD). Mature NGF protein is processed from a larger precursor, proNGF. We demonstrate that proNGF is the predominant form of NGF in mouse, rat, and human brain tissue, whereas little or no mature NGF is detected. Previous reports showed NGF protein, measured by ELISA, is increased in AD BFCN target regions such as hippocampus and cortex. Using Western blotting, we demonstrate a twofold increase in proNGF in AD parietal cortex compared to controls, indicating that it is this precursor form, proNGF, that accumulates in AD. This increase may reflect either a role for biologically active proNGF or posttranslational disturbances in NGF biosynthesis that decrease the processing of proNGF to mature NGF in AD., (Copyright 2001 Academic Press.)

Non-transferrin-bound iron (NTBI) uptake has been reported to follow two pathways, Ca(2+)-dependent and Ca(2+)-independent (Wright, T. L., Brissot, P., Ma, W. L., and Weisiger, R. A. (1986) J. Biol. Chem. 261, 10909-10914; Sturrock, A., Alexander, J., Lamb, J., Craven, C. M., and Kaplan, J. (1990) J. Biol. Chem. 265, 3139-3145). Studies reporting the two pathways have ignored the weak interactions of Ca(2+) with the chelator nitrilotriacetate (NTA) and the reducing agent ascorbate. These studies used a constant ratio of total Fe(2+) to NTA with and without Ca(2+). We observed Ca(2+) activation of NTBI uptake in PC12 cells with the characteristics reported for other cells upon using 1 mm ascorbate and a constant ratio of total Fe(2+) to NTA with or without Ca(2+). However, Ca(2+) did not affect NTBI uptake in solutions without NTA. We then determined conditional stability constants for NTA binding to Ca(2+) and Fe(2+) by potentiometry under conditions of NTBI uptake experiments (pH, ionic strength, temperature, ascorbate, total Fe(2+), and total Ca(2+) concentrations). In solutions based on these constants and taking Ca(2+) chelation into account, Ca(2+) did not affect NTBI uptake over a range of free Fe(2+) concentrations. Thus, the Ca(2+) activation of NTBI uptake observed using the constant total Fe(2+) to NTA ratio was because of Ca(2+)-NTA chelation rather than an activation of the NTBI transporter itself. It is suggested that the previously reported Ca(2+) dependence of NTBI uptake be re-evaluated.

The physical improvement is so great following lung volume reduction surgery that there is growing opinion that a randomized, controlled trial is unnecessary. A randomized, controlled trial, it is argued, would deprive those patients randomly assigned to the nonsurgical treatment arm the 'benefit' of lung volume reduction surgery. Entering a trial in which one arm leads to a surgical intervention and the other to best medical management also poses a variety of ethical difficulties. If one is to be offered surgery, there must be perceived benefit because the physician has an obligation to offer the best possible treatment for his or her patient. If a patient agrees to have surgery, the expectation is that surgery would help. Thus, a patient randomly assigned to the medical arm of a trial may easily believe that he or she is being deprived of surgery that may help them. This paper illustrates this dilemma using the Canadian Lung Volume Reduction Surgery Trial. The authors discuss the concept of 'equipoise' in three dimensions, adding community equipoise to theoretical equipoise and clinical equipoise earlier described by Freedman. The paper concludes that the Canadian Lung Volume Reduction Surgery Trial needs to continue because of the clinical equipoise that drives it.

As part of a project to examine health care ethics consultation in Canada, we surveyed individuals who were considered by themselves or others to play a significant role in health care ethics consultation. Since one goal of the project was to examine the education and abilities necessary for consultants, we sought to determine the qualifications and skills currently possessed by persons considered to be ethics consultants. For the purposes of the questionnaire, 'health care ethics consultation' was defined broadly to include consultation on ethical issues in clinical care or in clinical research, ethics consultation to Clinical Ethics Committees, Research Ethics Committees, and policy formulation committees in health care institutions; 'clinical ethics work' was defined more broadly still to include, in addition to the above, ethics education, administration, research and writing on bioethics other than the above, and public speaking. Three hundred and fifty questionnaires were sent to individuals and institutions across Canada that were thought to have some involvement in health care ethics consultation. Two hundred and fifty-three questionnaires were returned for a response rate of 72%. This report presents initial findings of the study and attempts to provide a comprehensive overview of the current state of ethics consultation within Canada. The survey examines demographics, educational background, time spent on ethics, institutional affiliations, approaches to the role of consultation, research related issues, and attitudes toward certification. Of the 253 questionnaires returned, 162 were completed by individuals who indicated that they provided some kind of ethics consultation. Of these, 43 indicated that they spent 30% or more of their time in clinical ethics work. These individuals are quite heterogeneous in background, training and activities, and while the great majority of them are based in an academic setting (university or teaching hospital), many act as resources to community hospitals, long-term care facilities and other organizations. Finally, the survey found that respondents' views on the advisability of certification for those offering ethics consultation were split evenly between those in favour of and those against certification. This report serves, then, as a reference point for studying the roles, responsibilities, training and accreditation of ethics consultants in health care.

Nerve growth factor (NGF) is a polypeptide that is required for normal development and maintenance of the sympathetic and sensory nervous systems. Skin has been shown to contain relatively high amounts of NGF, which is in keeping with the finding that the quantity of NGF in a tissue is proportional to the extent of sympathetic innervation of that organ. Since the keratinocyte, a major cellular constituent of the skin, is known to produce other growth factors and cytokines, our experiments were designed to determine whether keratinocytes are a source of NGF. Keratinocyte-conditioned media from the keratinocyte cell line PAM 212 contained NGF-like activity, approximately 2-3 ng/ml, as detected by the neurite outgrowth assay. Freshly isolated BALB/c keratinocytes contained approximately 0.1 ng/ml. Using a cDNA probe directed against NGF, we demonstrated the presence of a 1.3-kb NGF mRNA in both PAM 212 and BALB/c keratinocytes. Since ultraviolet radiation (UV) is a potentially important modulating factor for cytokines in skin, we examined the effect of UV on NGF mRNA expression. Although UV initially inhibited the expression of keratinocyte NGF mRNA (4 h), by 24 h an induction of NGF mRNA was seen. The NGF signal could also be induced by phorbol esters. Thus, keratinocytes synthesize and express NGF, and its expression is modulated by UVB and phorbol esters.

Neonatal sympathectomy of spontaneously hypertensive rats (SHR) and control Wistar-Kyoto rats (WKY) was performed by a combined treatment with antiserum to nerve growth factor and guanethidine during the first 4 weeks after birth. The development of hypertension was completely prevented in the treated SHR: at 28 to 30 weeks of age, systolic blood pressure of treated SHR was 139 +/- 2 mm Hg as compared with 195 +/- 8 mm Hg in untreated SHR. The extent of sympathectomy was verified by histofluorescence. Fluorescence histochemistry for catecholamine-containing nerves showed a complete absence of adrenergic nerves in the mesenteric arteries of treated rats. A supersensitivity to norepinephrine was exhibited by mesenteric arteries, anococcygeus muscle, and tail arteries from the treated SHR and WKY. In the mesenteric vascular bed, maximal response to norepinephrine was significantly reduced by sympathectomy. Sympathectomy also abolished the responses (e.g., generation of excitatory junctional potentials) of tail arteries to electrical stimulation of perivascular nerves. Morphometric measurements of three categories of mesenteric arteries showed that sympathectomy had no effect on the hypertrophic change of smooth muscle cells in the conducting vessels, but it prevented the hyperplastic changes of the muscle cells from reactive, muscular arteries and small resistance vessels. These results suggest that one of the primary roles of the overactive sympathetic nervous system in the development of hypertension in SHR is manifested through its trophic effect on the arteries of SHR. This trophic effect appears to cause a hyperplastic change in the smooth muscle cells in the reactive and resistance vessels, thereby contributing to the development of hypertension in older SHR.

Although ganglia from neonatal mouse sympathetic ganglia require nerve growth factor (NGF) for survival in culture, explanted sympathetic ganglia from early embryonic stages do not require added NGF for survival and growth. To determine whether the change in growth factor requirement is due to changes in the neurons themselves, to variations in neuronal populations, or to changes in nonneuronal cells, we examined the response to growth factors by dissociated sympathetic neurons at various stages of development. Results indicate that neurons from the 14-day gestational (E14) superior cervical ganglion (SCG) do not require NGF for initial survival and neurite extension, but do require the conditioned medium neurite extension factor, CMF. By 2 to 3 days thereafter, whether in vivo or in culture, most neurons have developed a requirement for NGF for survival in culture. During the same period, there is a concomitant increase in responsiveness to NGF alone as a trophic agent. Changes in response to NGF are not due to changes in NGF content of ganglia, to interactions in culture with nonneuronal cells, or to age-related differences in NGF requirements for maximum survival. The changes in growth factor requirements may be related to mechanisms regulating specificity of nerve-target connections.

A new neuronal growth factor (CMF) isolated from mouse heart-cell-conditioned medium stimulates morphologic and biochemical development of mouse embryo sympathetic neurons [Coughlin et al, 1981]. Further analysis of CMF by chromatographic and electrophoretic procedures has shown that under nondissociating conditions, CMF activity is associated with very high molecular weight material. All biological activity eluted within the included volume of a Sepharose CL-2B column in a molecular weight range corresponding to approximately 5 X 10(6) daltons. Similarly, electrophoresis showed no activity and very little protein entering 3% polyacrylamide gels, whereas both protein and activity migrated through 0.6% agarose-1.2% acrylamide composite gels. To further characterize the biological effects of CMF on normal neuronal development, antibodies to CMF were employed. Rabbits immunized against CMF developed high titres of antibodies with activity specifically directed against CMF (anti-CMF). Although anti-CMF inhibited nerve growth factor (NGF)-stimulated neurite outgrowth from the neonatal superior cervical ganglion, it did not inhibit the NGF-stimulated increase in tyrosine hydroxylase activity. Moreover, ganglia incubated for 3 days in the presence of anti-CMF were subsequently capable of producing neurites when washed and cultured in medium free of antiserum. Thus, anti-CMF specifically blocked neurite extension without causing cell death or irreversible damage in ganglionic explants. Our observations suggest, therefore, that CMF or antigenically similar material is a requirement for neurite extension.

The effects of 2.5S nerve growth factor (NGF) and epidermal growth factor (EGF), isolated from mouse submaxillary glands, on histamine release from rat peritoneal mast cells (PMCs) were studied. In the absence of phosphatidylserine, NGF (1 ng/ml to 1 microgram/ml) did not cause histamine release from PMCs isolated from normal rats and those infected with the nematode Nippostrongylus brasiliensis. However, when PMCs (greater than 97% pure) were preincubated with NGF and then challenged with worm antigen (Ag), there was a marked enhancement of histamine release (approximately twofold with a maximum effect at 10 ng/ml of NGF [3.8 X 10(-10) mol/L]) compared with the release induced by Ag alone. EGF (1 ng/ml to 1 microgram/ml) neither produced histamine release from PMCs in the presence of phosphatidylserine nor enhanced Ag-induced histamine release. This suggests that NGF acts directly on PMCs by activation of cell-surface receptors. The early kinetics of Ag-induced histamine release were altered by NGF that increased the initial rate at 15 seconds but did not prolong the overall duration of histamine release. Simultaneous addition of Ag and NGF did not cause enhanced histamine release; thus, some preincubation time with NGF (5 minutes or less) was required for the activation of PMCs. Moreover, after PMCs were activated by NGF, that state persisted for 1 hour, even when unbound NGF was removed by washing, and thereafter subsided gradually. Further studies revealed that NGF enhanced histamine release induced by concanavalin A, compound 48/80, and ionophore A23187. These results suggest that NGF might be an important molecule in inflammatory responses through the regulation of mediator release from mast cells.

In the rat, there is considerable evidence of mast cell/nerve interaction both in the normal and infected intestine. Between 67 and 87% of all mast cells in the intestinal lamina propria of rats infected 22-35 days earlier with Nippostrongylus brasiliensis were touching nerves. These membrane contacts were between subepithelial mast cells and nonmyelinated nerves containing substance P, calcitonin gene-related peptide and neurone specific enolase. 2.5S nerve growth factor (NGF) has a significant enhancement effect on antigen-induced histamine release without addition of phosphatidylserine, and the in vivo administration of NGF to rats causes both connective tissue and mucosal mast cells to dramatically increase in number. All of these effects are both dose dependent and NGF specific, as evidenced by inhibition with anti-NGF. 2.5S NGF also causes in vitro increase of colonies in methylcellulose cultures of human peripheral blood. The effects of NGF in this system are synergistic with other T cell-derived growth factors and relatively specific for metachromatic cell growth. These observations support the conclusions that nerves and mast cells may constantly communicate and provide a structural and conceptual framework whereby the central nervous system may communicate with inflammatory events.

Nerve growth factor (NGF) is a neurotropic polypeptide necessary for the survival and growth of some central neurons, as well as sensory afferent and sympathetic neurons. Much is now known of the structural and functional characteristics of NGF, whose gene has recently been cloned. Since it is synthesized in largest amounts by the male mouse submandibular gland, its role exclusively in nerve growth is questionable. NGF also causes histamine release from rat peritoneal mast cells in vitro, and we have shown elsewhere that it causes significant, dose-dependent, generalized mast cell proliferation in the rat in vivo when administered neonatally. Our experiments now indicate that NGF causes a significant stimulation of granulocyte colonies grown from human peripheral blood in standard hemopoietic methylcellulose assays. Further, NGF appears to act in a relatively selective fashion to induce the differentiation of eosinophils and basophils/mast cells. Depletion experiments show that the NGF effect may be T-cell dependent and that NGF augments the colony-stimulating effect of supernatants from the leukemic T-cell (Mo) line. The hemopoietic activity of NGF is blocked by polyclonal and monoclonal antibodies to NGF. We conclude that NGF may indirectly act as a local growth factor in tissues other than those of the nervous system by causing T cells to synthesize or secrete molecules with colony-stimulating activity. In view of the synthesis of NGF in tissue injury, the involvement of basophils/mast cells and eosinophils in allergic and other inflammatory processes, and the association of mast cells with fibrosis and tissue repair, we postulate that NGF plays an important biological role in a variety of repair processes.

The morphologic and biochemical development of the embryonic mouse superior cervical ganglion was characterized in vivo and in tissue culture. From 13 days of gestation, when the superior cervical ganglion was first visible, to birth at 19 days, tyrosine hydroxylase [tyrosine 3-monooxygenase; L-tyrosine, tetrahydropteridine:oxygen oxidoreductase (3-hydroxylating); EC 1.14.16.2] activity increased 100-fold in vivo. Explants of ganglia from 14-day embryos exhibited abundant neurite outgrowth in basal medium without added nerve growth factor (NGF), and increases in tyrosine hydroxylase activity paralleled that observed in vivo. Ganglia from 14-day embryos elaborated neurites and exhibited 3-fold increases in enzyme activity in vitro in the presence of antiserum to NGF (anti-NGF) or NGF + anti-NGF. In direct contrast, ganglia from 18-day fetuses failed to grow without added NGF or in medium containing anti-NGF or NGF + anti-NGF: virtually no axon outgrowth occurred and tyrosine hydroxylase activity decreased by half. These observations suggest that developmental regulatory mechanisms change radically during embryologic and fetal life of mammalian superior cervical ganglion.

In liquid cultures of human cord blood mononuclear cells, the activities of the 2.5S nerve growth factor (NGF) inducing basophil and eosinophil differentiation were investigated. Various concentrations of immunopurified 2.5S NGF derived from murine submaxillary glands were added to cultures with or without conditioned medium from a human T cell line (Mo-CM), which has previously been shown to produce activities stimulating granulocyte-macrophage colonies. Addition of NGF led to significant increases in differentiation of basophilic cells accompanied by histamine synthesis at 2 weeks in vitro; eosinophil differentiation was not increased in these cultures. In addition, NGF could be shown to amplify basophil differentiation induced by Mo-CM, and the activity of NGF inducing basophil differentiation was dependent on the presence of T lymphocytes. These results indicate that NGF stimulates T-lymphocyte-dependent basophilic cell differentiation from human cord blood progenitors and may in this way support differentiation of basophils or mast cells in vivo at sites of allergic tissue inflammation.