Tumor microRNA-126 controls cell viability and associates with poor survival in patients with esophageal adenocarcinoma

Esophageal adenocarcinoma displays a poor prognosis and current treatments are often not curative. Pathological TNM-stage is a prognostic parameter, but a better understanding of the pathophysiology of esophageal adenocarcinoma is needed to better predict survival. Recent work in other malignancies indicated an important role for the regulator microRNA-126 (miR-126) in tumors. The aim of this study was to investigate the function of miR-126 in esophageal adenocarcinoma and to correlate expression of miR-126 with tumor cell behavior and patient survival. Functional assays were performed in esophageal adenocarcinoma cell lines (OE33) in vitro by overexpressing or antagonizing miR-126 and assessing cellular processes linked to the hallmarks of cancer. In vivo pre-treatment biopsies of 58 patients with esophageal adenocarcinoma who underwent neoadjuvant chemoradiotherapy and surgery were analyzed for miR-126 expression in tumor cells by qRT-PCR and patient survival was analyzed by Kaplan–Meier and Cox regression. In OE33 cancer cells, stable overexpression of miR-126 modest though significantly altered expression of genes related to cell death (MEK1) and DNA repair (POLB and TERF1) was observed. Also the secretion of the angiogenic and pro-inflammatory factors, VEGF, IL-1β, and IL-6 were regulated by miR-126 ( P < 0.029). Importantly, miR-126 was found to be a regulator of cell viability in OE33 cells. Overexpressing ( P = 0.043) and antagonizing ( P = 0.035) miR-126 showed reciprocal effects on tumor cell viability and significantly regulated expression of pro- and anti-apoptotic genes, TP53, and GATA6 ( P < 0.031). In patients, high levels of miR-126 expression in pre-treatment tumors were significantly associated with poor survival ( P = 0.031). In multivariable analysis, high miR-126 ( P = 0.038) together with ypN-stage ( P = 0.048) were shown to be independent risk factors for poor survival. In conclusion, high expression of miR-126 in esophageal adenocarcinoma prevents tumor-cell death and is associated with poor patient survival. This study warrants further analysis of miR-126 as biomarker or potential therapeutic target for OAC.

Impact statement

Esophageal adenocarcinoma is a common form of cancer of the esophagus. It has an increasing health impact as it is associated with very poor patient survival. A better understanding of the pathophysiology of this cancer is needed to identify better treatment strategies and to provide a better prognosis for these patients. MicroRNAs have emerged as important molecular regulators of cancer cell viability and proliferation. The aim of our study was to investigate the role of one very well established microRNA, miR-126, in esophageal adenocarcinoma. Our research shows clear experimental evidence that miR-126 controls cell viability of esophageal adenocarcinoma cells. High (over)expression of miR-126 increased the viability of these cells. Our preclinical data were shown to be clinically relevant for this field of oncology. In an independent validation study of esophageal adenocarcinoma biopsies, we confirmed that high miR-126 expression in tumor cells was an independent risk factor for poor patient survival.

Recovery Star: validating user recovery

Aims and method

Mental Health Recovery Star is a multifaceted 10-item outcomes measure and key-working tool that has been widely adopted by service providers in the UK. We aimed to explore its factorial validity, internal consistency and responsiveness. Recovery Star readings were conducted twice with 203 working-age adults with moderate to severe mental health problems attending a range of mental health services, and a third time with 113 of these individuals.

Results

Mental Health Recovery Star had high internal consistency and appeared to measure an underlying recovery-oriented construct. Results supported a valid two-factor structure which explained 48% of variance in Recovery Star ratings data. Two Recovery Star items (‘relationships’ and ‘addictive behaviour’) did not load onto either factor. There was good statistically significant item responsiveness, and no obvious item redundancy. Data for a small number of variables were not normally distributed and the implications of this are discussed.

Clinical implications

Recovery Star has been received enthusiastically by both mental health service providers and service users. This study provides further evidence for its adoption in recovery-focused mental health services and indicates that items relating to addictive behaviour, responsibilities and work could be further developed in future.

Managing outcome performance in mental health using HoNOS: experience at St Andrew's Healthcare

Aims and Method

Modern mental healthcare providers must demonstrate service-level clinical effectiveness to key stakeholders. We introduced two performance indicators of clinical effectiveness based on outcome data from routinely collected Health of the Nation Outcome Scales (HoNOS) and HoNOS–secure assessments across St Andrew's Healthcare, a charity providing in-patient services in Northampton and Essex. We present outcome data from the period 2004–2007.

Results

The indicators showed consistent 90-day improvement rates and increasing stability over time. the validity of results is supported by levels of change along predicted lines among different patient cohorts.

Clinical Implications

It is possible and beneficial to use routine outcome measures to demonstrate clinical effectiveness at service level. the future of managing mental health outcomes will be in electronic health records systems.

Dangerousness in firesetters: a survey of psychiatrists' views

Aims and Method

The assessment of the future dangerousness of firesetters is problematical but psychiatrists may be requested to perform assessment of arsonists for the courts. We surveyed the views of psychiatrists and others (n=54) on how 11 candidate historical variables might contribute to future dangerousness.

Results

Hierarchical cluster analysis indicated that variables fell into three groups related to level of perceived dangerousness. Apparent intention to endanger life and setting fire to an occupied building were the items thought by psychiatrists to most indicate highest future dangerousness. Having previously set fires that caused extensive damage, failure to extinguish previous fires or alert the authorities were perceived as indicating moderate future dangerousness.

Clinical Implications

The study adds to what is known about how psychiatrists formulate assessments of future dangerousness.

Protecting patients in psychiatric care: the St Andrew's Human Rights Project

Aims and Method

The Human Rights Act was incorporated into UK law in 2000, but little is known about how it is implemented in psychiatric care. We explored the understanding of multidisciplinary teams of the restriction and protection of patients' human rights using an open-response questionnaire. Content analysis was employed to summarise written, narrative data about the human rights of 102 patients in secure psychiatric care.

Results

Our clinical teams considered human rights to be protected through risk assessment and management, ongoing monitoring, local policy and existing UK mental health legislation. Understanding of the proper and proportionate restriction of ‘qualified’ rights (such as article 5 liberty) and the positive enablement and promotion of human rights (such as article 8 family and private life) appeared to be limited.

Clinical Implications

A cultural shift in focus is required in mental health services to understand and ensure positive promotion of human rights. Clinicians should directly address the human rights of their patients and articulate the rationale for proportionate restrictions of qualified rights. Clinical policy, training and audit should explicitly embody the protection of human rights.

Nursing and midwifery students' encounters with poor clinical practice: A systematic review

The aim of this paper was to systematically review evidence about nursing and midwifery students' encounters with poor clinical care. We undertook a systematic review of English language empirical research using multiple databases from inception to April 2016. Hand searching was also undertaken. Included papers contained accounts of empirical research which reported on students' encounters with poor care. These were quality-assessed, information was extracted into tables, and study results were synthesized using thematic analysis. N = 14 papers met inclusion criteria; study quality was moderate to good. Study synthesis revealed four themes: i) encounters with poor practice: students encounter poor practice that is likely to be worthy of professional sanction; ii) while intention to report is high in hypothetical scenarios, this appears not always to translate to actual practice; iii) a range of influencing factors impact the likelihood of reporting; iv) the consequences of encountering and subsequently reporting poor practice appeared to have a lasting effect on students. Research is required to determine the frequency and nature of students' encounters with poor care, when and where they encounter it, how to increase the likelihood that they will report it, and how they can be supported in doing so.

Medicines management: an interview study of nurses at a secure psychiatric hospital

AIMS

To explore mental health nurses' knowledge, attitudes and clinical judgement concerning medicines management in an inpatient setting with a view to enhancing training.

BACKGROUND

Medicines management is a key role of mental health nurses, but little research has been conducted into their training needs.

DESIGN

An exploratory mixed-methods design was used involving individual interviews with participants to investigate their responses to hypothetical medicine administration scenarios.

METHODS

Interviews were held with a convenience sample of 50 Registered Nurses working in a specialist mental health hospital between November 2012-February 2013. Participants were presented with clinical vignettes describing eight scenarios they might encounter as part of their medicines management role and asked about how they would respond. Responses were assessed by two independent raters against ten quality standards underpinning the vignettes.

RESULTS

The median number of responses that were judged to demonstrate adequate awareness of associated quality standards was 4 (range 1-7), indicating that many participants did not appear to be aware of, or compliant with, current UK medicines management guidance and local policy. Many would not report a 'near miss' or medicines administration error. There was a lack of awareness of guidance on verbal prescribing, consent to treatment rules and the administration of off-label/unlicensed drugs. Past year attendance on a medicines management course, time since registration and self-reported knowledge of national standards for medicines administration did not discriminate between total score on the 10 quality standards.

CONCLUSION

The medicines management training needs of participants appeared not to be fully met by the existing learning sources. The use of vignettes to assess nurses' training needs requires evaluation in other settings.

A case series of clozapine for borderline personality disorder

BACKGROUND

Borderline personality disorder (BPD) is a common, debilitating disorder for which the evidence base for treatment is modest. This case series aimed to explore preliminary evidence of clozapine's effectiveness for patients with severe BPD.

METHODS

We examined the case notes of 22 female inpatients with a primary diagnosis of BPD who had started treatment with clozapine. Baseline routine clinical data were extracted from the records and at 6 monthly intervals thereafter, up to a maximum of 18 months after starting treatment. Patients also were interviewed about their experiences.

RESULTS

We found evidence for a beneficial effect of clozapine across several clinical domains. Symptom severity, need for enhanced observations, use of additional medication, and the number of aggressive incidents all significantly improved after clozapine. The greatest improvements appeared within the first 6 months of initiating treatment. There also was a significant increase in weight.

CONCLUSIONS

The results suggest that clozapine, with suitable health monitoring, may be beneficial for this clinical population. Larger, randomized, blinded, and controlled prospective studies are needed to confirm these findings.

A systematic review of the terms used to refer to people who use mental health services: user perspectives

OBJECTIVE

The terms used to refer to people who receive mental healthcare have been described as either potentially stigmatizing or empowering. This paper systematically reviews empirical studies of terminological usage in order to ascertain current knowledge.

METHODS

Multiple databases were searched using the terms 'patient', 'client', 'service user' and 'consumer'. Empirical, English language studies were included where an aim was to measure outcome related to the various terms used to describe or refer to people who use mental health services. Studies were assessed (i) against a hierarchy of evidence and (ii) using a 12-item checklist of methodological quality.

RESULTS

The search resulted in the screening of 13,765 abstracts; full text versions of 69 papers were examined and 11 studies that met the inclusion criteria were identified. All were cross-sectional surveys and all measured participant preference. Nine studies satisfied four or fewer quality markers. 'Client' and 'patient' were the terms preferred by study participants.

CONCLUSIONS

Despite a stream of debate in editorial columns and letters pages, it is unclear whether terminological use is important to the people who use mental health services. Preference is the sole outcome investigated empirically. Methodological rigour of extant study findings is largely questionable. Generalization and interpretation from included studies should be approached very cautiously.

Potential severity of aggressive behaviour after acquired brain injury: implications for recording

Aggression is a consequence of acquired brain injury that may necessitate admission to neurobehavioural services. The 'Overt Aggression Scale - Modified for Neurorehabilitation' (OAS-MNR) is a valid, reliable means of capturing this. A criticism of observational rating scales is they do not reflect factors like intent to harm which results in recording anomalies. 'Attacks' has been proposed as a measure which achieves this within psychiatric settings. Principal goals of this study are to determine the usefulness of measuring similar concepts in neurobehavioural services and further validating both scales. A total of 1066 physical assaults were recorded in 6 weeks by 25 patients in an inpatient neurobehavioural programme using the OAS-MNR. Fifty incidents were also rated on Attacks. Convergent validity for using both measures in neurobehavioural services was found. Modifying OAS-MNR severity scores using one of two factors found to underlie Attacks produced an index that successfully discriminated incidents whose risk necessitated more intrusive intervention, which was not evident otherwise. Modifying scores that objectively reflect severity of physical assaults using measures of perceived intent should be a feature of observational recording scales such as the OAS-MNR. Ensuring robust inter-rater reliability will be essential in any development work.

An audit of the use of breakaway techniques in a large psychiatric hospital: a replication study

This paper describes an audit study of the effectiveness of breakaway training conducted in a specialist inpatient mental health hospital. Breakaway techniques comprise a set of physical skills to help separate or break away from an aggressor in a safe manner, but do not involve the use of restraint. Staff (n= 147) were assessed on their ability to break away from simulations of potentially life-threatening scenarios in a timely manner, and using the techniques taught in annual breakaway or refresher training. We found that only 14% (21/147) of participants correctly used the taught techniques to break away within 10 s. However, 80% of people were able to break away from the scenarios within 10 s but did not use the techniques taught to them. This audit reinforces questions about breakaway training raised in a previous study. It further demonstrates the need for a national curriculum for physical intervention training and development of the evidence base for the content of such training as a priority.

Physical assault by patients against physiotherapists working in mental health settings

OBJECTIVES

There is a lack of empirical research about physical assault by patients against physiotherapists who work in mental health settings. This study aimed to ascertain the lifetime prevalence and 12-month incidence of assault by patients against physiotherapists in UK mental health settings. This research will inform the development of pre- and post-registration training programmes for physiotherapists.

DESIGN

Postal questionnaire survey.

PARTICIPANTS

Members of the Chartered Society of Physiotherapists' special interest group for physiotherapists working in the field of psychiatry.

MAIN OUTCOME MEASURES

Self-reported experience of physical assault by patients. Secondary outcome was self-reported training received to manage violent and aggressive patients.

RESULTS

Questionnaires were returned by 116/178 (65%) special interest group members. Fifty-one percent (59/116) reported that they had been assaulted at work during their career, and 24% (28/116) had been assaulted by a patient in the previous 12 months. Physiotherapists in mental health settings appear to be at greater risk of assault by patients than other non-nursing clinicians.

CONCLUSIONS

Physiotherapists who work in mental health are at similar risk of physical assault by patients as their nursing colleagues, who are required by the UK Nursing and Midwifery Council to receive education and training in the prevention and management of aggression and violence in their pre-registration training. The authors recommend that appropriate training should be included in pre-registration programmes for physiotherapists.

Portrayal of mental illness and special hospitals in the UK press

The portrayal of mental illness in the media can be negative and stigmatizing. Mental health nurses, therefore, need to be aware of the ways in which the media frame mental illness issues, and should be prepared to challenge inaccuracy. This article examines the changing nature of the UK press's reporting of mental health issues by focusing on two areas. First, the changing terminology the press uses in their attempt to appear more sensitive, exemplified by recent growth in use of the term 'suicide watch'. Secondly, the article examines the press' reporting of the three English high-security special hospitals as an example of how the framing and personalization of stories is used to set the public agenda on mentally disordered offenders.

Characteristics of low IQ arsonists at psychiatric assessment

We conducted a retrospective study of arsonists referred for psychiatric assessment and found that 88/202 (43.6%) had an IQ of 85 or below. The low IQ group showed more evidence of childhood temperamental disturbance, and a later pattern of internal problems rather than external factors expressing themselves as fire-setting. This study highlights the likelihood of lifelong, temperamental problems being apparent in childhood, and being predictive and possibly causative of fire setting in people with a low IQ. Better understanding of the distinct characteristics of lower IQ arsonists is essential for improved prevention, treatment and management.

Dose form modification - a common but potentially hazardous practice. A literature review and study of medication administration to older psychiatric inpatients

BACKGROUND

Many older patients have difficulty in swallowing their tablets and capsules. Dose form modification, by crushing tablets or opening capsules, is often used by nurses to administer such medication.

METHODS

Electronic searches of five literature databases on tablet crushing and capsule opening were carried out. A review of medication incident reports involving tablet crushing from the U.K. National Reporting and Learning System (NRLS) was also undertaken. An observational study of medication administration on two long-stay wards for older mentally ill inpatients was carried out in a large psychiatric hospital.

RESULTS

Only 17 incidents involving tablet crushing were reported to NRLS in 13 months. In the observational study, the administration of 1257 oral doses of medication at 36 medication rounds was observed. Tablets were crushed or capsules opened for 25.5% (266/1045) of solid oral doses. For 44.0% (117/266) of these doses the tablet crushing had not been authorized by the prescriber. For 4.5% (12/266) of doses crushing was specifically contra-indicated by the manufacturer. In 57.5% (153/266) of doses, tablet crushing was avoidable by the correct use of more suitable preparations. Crushing caused contamination, spillage and hygiene problems.

CONCLUSIONS

Although tablet crushing and capsule opening are common practices, they are rarely reported as causing patient harm. Tablet crushing can often be avoided by the use of more suitable preparations. Crushing tablets and opening capsules are contra-indicated for some preparations. Older patients' medication may benefit from review by a pharmacist in order to optimize safe medication administration. Where tablet crushing is unavoidable, attention to cleanliness, contamination and spillage are necessary.

Delegation of medication administration: an exploratory study

AIM

To examine the delegation of medication administration, including the frequency of delegation, whether delegation was to a care worker or a registered nurse (RN) and whether care workers were directly supervised when administering medication.

METHOD

Administration of 1313 medication doses was observed on two inpatient psychiatric wards for older people.

RESULTS

Administration was delegated by the nurse preparing the medication for four out of every five doses, usually to another registered nurse (78% of delegated doses), but also to care workers (22%). Care workers were more likely to administer medications to confused and aggressive patients than were registered nurses.

CONCLUSION

Care workers who undertake delegated medication administration should receive regular training to ensure safety. Nurses remain accountable for delegated medication administration.

Gender differences amongst adult arsonists at psychiatric assessment

Reports of gender differences amongst arsonists at psychiatric assessment are not uncommon, however some are based on relatively small samples. A new retrospective study highlighting gender differences could help to confirm or refute the current state of knowledge. The aim of the current study was to examine gender differences amongst a sample of 167 adult arsonists (129 males and 38 females). Information was collected from clinical records on sociodemographic, family background and childhood factors; adult adjustment; fire setting history; motives; features of pyromania and other offending, from the case notes of a group of arsonists referred to the West Midlands Psychiatry Service over a 24-year period. Female arsonists were older than males and more likely to have a psychiatric diagnosis. Women more frequently had a history of sexual abuse, while men had a more varied criminal background and more substance abuse problems. Our findings largely support previous research, and are discussed in this context, whilst also bringing attention to a more recently developed theory (Action System Model). Significant gender differences amongst arsonists indicates that different emphases in the treatment of male and female arsonists may be advisable, though a reliable evidence base for treatment has yet to be established.

An observational study of medication administration errors in old-age psychiatric inpatients

BACKGROUND

Relatively little is known about medication administration errors in mental health settings.

OBJECTIVE

To investigate the frequency and nature of medication administration errors in old-age psychiatry. To assess the acceptability of the observational technique to nurse participants.

METHOD

Cross-sectional study technique using (i) direct observation, (ii) medication chart review and (iii) incident reports.

SETTING

Two elderly long-stay wards in an independent UK psychiatric hospital.

PARTICIPANTS

Nine nurses administering medication at routine medication rounds.

MAIN OUTCOME MEASURES

Frequency, type and severity of directly observed medication administration errors compared with errors detected by retrospective chart review and incident reports.

RESULTS

Using direct observation 369 errors in 1423 opportunities for errors (25.9%) were detected vs. chart review detected 148 errors and incident reports none. Most errors were of doubtful or minor severity. The pharmacist intervened on four occasions to prevent an error causing patient harm. The commonest errors observed were unauthorized tablet crushing or capsule opening (111/369, 30.1%), omission without a valid reason (100/369, 27.1%) and failure to record administration (87/369, 23.6%). Among the nurses observed, the error rate varied widely from no errors to one error in every two doses administered. Of the seven nurses who completed the post-observation questionnaire, all said they would be willing to be observed again.

CONCLUSION

Medication administration errors are common and mostly minor. Direct observation is a useful, sensitive method for detecting medication administration errors in psychiatry and detects many more errors than chart review or incident reports. The technique appeared to be acceptable to most of the nursing staff that were observed.

Smoking in a forensic psychiatric service: a survey of inpatients' views

Smoking in a forensic psychiatric service: a survey of inpatients' views Very little is known concerning the views and beliefs of psychiatric inpatients about smoking in hospital. We conducted a survey of inpatients from the forensic wards of a large independent psychiatric hospital using a structured interview to collect data about their views on smoking. Of 102 patients eligible to participate, 45 (44.1%) agreed to do so. Most participants (34, 75.6%) were current smokers. Most smokers thought it was just too difficult to give up smoking (25, 73.5%). They cited seeing staff and other patients smoking, as well as the smoky atmosphere on the ward, as barriers to quitting. The majority of participants (35, 77.8%) thought that staff should be allowed to smoke with patients. Smokers held more liberal views about smoking than non-smokers. A smaller proportion of non-smokers than smokers were happy with the hospital smoking policy, as reflected in the ward rules about smoking. The results of this survey suggest that a change in attitude and culture towards smoking may be needed in psychiatric units. Smokers should be regularly offered help and encouragement to quit. Psychiatric care staff should carefully consider whether their own smoking behaviour undermines their patients' attempts to stop smoking. More attention should be given to the views and needs of non-smokers.

A review of medication administration errors reported in a large psychiatric hospital in the United kingdom

A retrospective analysis of reports of medication administration errors over a period of three and a half years was carried out in a UK psychiatric hospital. A total of 112 errors and "near misses" were studied. The reporting rate increased over time. Psychotropic, intramuscular, and as-needed medications were overrepresented in the error reports. Fifteen percent of the errors had the potential to cause moderate or severe harm to patients. The two most common factors cited by nurses as contributing to error causation were a busy, noisy environment and personal factors, such as feeling tired or unsupported. Physicians were cited as having contributed to some errors.

Nurses' perceptions of the working environment: a UK independent sector study

The working environment is an important determinant of employee well-being. Previous UK studies report registered nurses' perception of the working environment using the Work Environment Scale (WES), but surprisingly few include data for nurses working in mental health or learning disability settings. One hundred and sixty-one (58.8%) registered nurses working day shifts in five specialist divisions (forensic adult mental health, adolescent mental health, elderly continuing care, adult and adolescent learning disability and brain injury rehabilitation) of a large charitable hospital comprising mostly secure (i.e. 'locked') wards completed the WES. Nurses working in separate clinical divisions differed only on the 'physical comfort' subscale. These results are discussed in the context of previous UK research: this sample of nurses scored differently on a number of subscales, with the working environment characterized by relatively high levels of support, cohesion and managerial control and slightly lower levels of autonomy. It is unclear whether the differences reflect the organizational (i.e. non-NHS) context, or a secure environment effect. Previous studies of mental health nurses are now 10 years old and we present data that may provide a benchmark of perceptions of the working environment held by nurses working in mental health and learning disability settings.

Nerve growth factor (NGF)-induced calcium influx and intracellular calcium mobilization in 3T3 cells expressing NGF receptors

The neurotrophins have been implicated in the acute regulation of synaptic plasticity. Neurotrophin-stimulated presynaptic calcium uptake appears to play a key role in this process. To understand the mechanism of neurotrophin-stimulated calcium uptake, the regulation of calcium uptake and intracellular mobilization by nerve growth factor (NGF) was investigated using NIH 3T3 cells stably transfected with either the high affinity NGF receptor p140(trk) (3T3-Trk) or the low affinity NGF receptor p75(NGFR) (3T3-p75). In 3T3-Trk cells, NGF increased both calcium uptake and intracellular calcium mobilization. In 3T3-p75 cells, NGF increased calcium uptake but not intracellular calcium mobilization. K-252a alone increased intracellular calcium in 3T3-Trk cells but not in 3T3-p75 cells. Nifedipine, an inhibitor of calcium uptake through L-type calcium channels, inhibited the action of NGF on both 3T3-Trk cells and 3T3-p75 cells, indicating that both p140(trk) and p75(NGFR) receptors are linked to nifedipine-sensitive L-type calcium channels. These studies show that either NGF receptor will support increases in intracellular calcium but that p140(trk) does so by increasing both uptake and mobilization, whereas p75(NGFR) does so by increasing uptake only.

Expression of human p140trk receptors in p140trk-deficient, PC12/endothelial cells results in nerve growth factor-induced signal transduction and DNA synthesis

Nerve growth factor (NGF) regulates proliferation, differentiation, and survival of sympathetic and sensory neurons through the tyrosine kinase activity of its receptor, p140trk. These biological effects of NGF depend upon the signal-mediating function of p140trk substrates which are likely to differ from cell to cell. To define p140trk receptor substrates and the details of signalling by NGF in the hybrid cell PC12EN, we stably transfected cultures with a vector encoding a full-length human p140trk cDNA sequence. Two stably transfected clones, one expressing p140trk with higher affinity (PC12EN-trk3; Kd 57.4 pM, Bmax 9.7 pmole/mg) and one expressing p140trk with a lower affinity (PC12EN-trk1; Kd 392.4 pM, Bmax 5.7 pmole/mg) were generated. Radioreceptor assays indicate that transfected p140trk receptors show slow NGF-dissociation kinetics, are resistant to trypsin or Triton X-100 treatment, are specific for NGF compared to other neurotrophins, and are internalized or downregulated as are native PC12 p140trk receptors. NGF stimulates p140trk tyrosine phosphorylation in a dose- (0.01-10 ng/ml) and time- (5-120 min) dependent manner, and tyrosine phosphorylation was inhibited by 200-1,000 nM K-252a. NGF-induced Erk stimulation for 60 min was assessed using myelin basic protein as a substrate. NGF treatment also led to an increased phosphorylation of p70S6k, SNT, and phospholipase C gamma, demonstrating that the major NGF-stimulated signalling pathways found in other cells are activated in PC12EN-trk cells. Staurosporine (5-50 nM) rapidly and dBcAMP (1 mM) more slowly, but not NGF induced morphological differentiation in PC12EN-trk cells. Rather, NGF treatment in low-serum medium stimulated a 1.3- and 2.3-fold increase in DNA synthesis measured by [3H]thymidine incorporation in PC12EN-trk1 and PC12EN-trk3, respectively. These data highlight the functionality of the transfected p140trk receptors and indicate that these transfected cells may serve as a novel cellular model facilitating the study of the mitogenic properties of NGF signalling and the transducing role of the p140trk receptor substrates.

Both p140(trk) and p75(NGFR) nerve growth factor receptors mediate nerve growth factor-stimulated calcium uptake

Human p140(trk) and p75(NGFR) were transfected separately into 3T3 cells. Nerve growth factor stimulates calcium uptake into both transfectants but not into untransfected 3T3 cells. p140(trk) cells were stimulated maximally by 25 ng/ml; 100 ng/ml was submaximal for p75(NGFR) cells. K-252a inhibits the effect of NGF on p140(trk) cells but not on p75(NGFR) cells; brain-derived neurotrophic factor stimulates calcium uptake in p75(NGFR) cells but not in p140(trk) cells. The data suggest that both nerve growth factor receptors could be involved in the nerve growth factor-mediated actions of calcium on its target cells: neuronal survival, neuronal protection, and synaptic plasticity.

Involvement of protein kinase C in nerve growth factor- and K-252a-stimulated calcium uptake into PC12 cells

Both nerve growth factor (NGF) and K-252a stimulate the uptake of calcium into PC12 cells. Stimulation by either is prevented by pretreatment of the cells with the tumor promoter phorbol 12-myristate 13-acetate (PMA), suggesting an involvement of protein kinase C in the stimulation. The effect of PMA is specific in that the calcium uptake stimulated by either the L-type channel agonist BAY K 8644 or by ATP is not altered in PMA-pretreated cells. An involvement of kinase C is also suggested by the inhibition of NGF- or K-252a-stimulated calcium uptake by the kinase C inhibitors staurosporine and calphostin C. Inhibition by the isoform-specific agents GO 6976 and thymeleatoxin implicates one of the classic calcium-sensitive isoforms of kinase C. The close similarity in the profiles of inhibition of NGF-stimulated and K-252a-stimulated calcium uptake by the various effectors suggests that NGF and K-252a act on calcium uptake through some of the same signaling elements.

Characteristics of the K-252a-induced increase in calcium uptake in PC12 cells

K-252a treatment produced a 30-50% increase in the uptake of radioactive calcium by PC12 cells within 3-4 minutes. The increase in uptake was partially blocked by inhibitors of voltage-operated calcium channels, such as nifedipine, but not by inhibitors of receptor-operated calcium channels, such as nickel or suramin. Introduction of phosphatase 2A into the cells completely blocked the effect of K-252a. Long-term treatment of the cells with either K-252a or with nerve growth factor blocked the subsequent actions of either K-252a or nerve growth factor on calcium uptake, but neither altered the subsequent action of the L-channel agonist Bay K 8644 on calcium uptake. Calcium uptake was not stimulated by K-252a in PC12nnr, cells that have little or no high-affinity nerve growth factor receptors; cells expressing increased levels of high-affinity nerve growth factor receptors showed a response to K-252a comparable to that seen in parent PC12. The data suggest that the increased uptake of radioactive calcium produced by K-252a is mediated by a mechanism very similar to that serving the increased calcium uptake produced by nerve growth factor.

Differentiation of PC12 cells with K-ras: comparison with nerve growth factor

The cell line PC12, derived from a rat pheochromocytoma, has served as a model for studies on the mechanism of action of nerve growth factor, as well as for the exploration of neuronal differentiation in general. When treated with nanomolar concentrations of nerve growth factor, these neoplastic chromaffin-like cells stop dividing and acquire, for all intents and purposes, the phenotype of mature sympathetic neurons. This phenotype is characterized by the extensive outgrowth of electrically excitable neurites, the ability to form functional synapses, and the acquisition of a number of biochemical markers. Treatment of PC12 cells with retroviral vectors encoding the K-ras, the N-ras, or the v-src oncogenes also produces a marked morphological differentiation very similar to that seen upon treatment with nerve growth factor. Treated cells stop dividing and develop an extensive network of neurites. It has recently been shown that PC12 cells differentiated with v-src, while resembling, morphologically, those treated with nerve growth factor, differ substantially in the biochemical characteristics normally associated with nerve growth factor-induced differentiation. Cells infected with K-ras also develop a neurite network similar to that seen after treatment with nerve growth factor. In addition, such cells develop tetanus toxin-binding sites and saxitoxin-binding sites, as do cells treated with nerve growth factor. Decreases in the binding of epidermal growth factor and in the activity of calpain also occur and these, as well, are characteristic of nerve growth factor-treated cells. But the adhesive properties of cells infected with K-ras are different than those of nerve growth factor-treated cells, and the former do not show an increase in the NILE glycoprotein. Finally, K-252a, an inhibitor of the actions of nerve growth factor on PC12 cells, has no effect on the neurite outgrowth produced by infection with K-ras. Thus, many of the key markers of nerve growth factor-induced differentiation of PC12 cells also appear upon differentiation with K-ras, but there are, nevertheless, some crucial differences in the properties of these two sets of cells.

Differentiation of PC12 cells with v-src: comparison with nerve growth factor

The PC12 rat pheochromocytoma cell line is used extensively as a model to study neuronal differentiation. These cells resemble adrenal chromaffin cells, differentiating both morphologically and biochemically when cultured in the presence of dexamethasone, but develop a sympathetic neuron-like phenotype when cultured in the presence of nerve growth factor. Expression of the protein product of the v-src oncogene in PC12 cells also induces neurite outgrowth similar to that resulting from nerve growth factor treatment (Alema et al: Nature 316:557-559, 1985). It is thus possible that c-src or a src-like tyrosine kinase participates in the signal transduction pathway by which nerve growth factor acts on PC12 cells. In this study a temperature-sensitive v-src gene has been introduced into PC12 cells. When cultures of these src-transformed cells are switched from the nonpermissive (40 degrees C) to the permissive (37 degrees C) temperature they elaborate neurites. The differentiation induced by src has been compared with that induced by nerve growth factor by determining whether src-transformed PC12 cells at 37 degrees C exhibit the same biochemical alterations as those induced in PC12 cells treated with nerve growth factor. Neurite extension at 37 degrees C in v-src-transformed cells, like NGF-induced differentiation, is accompanied by an increase in the nerve growth factor-inducible large external (NILE) protein. However, neurite extension in v-src-transformed cells is not blocked by the protein kinase inhibitor K-252a, which completely blocks NGF-induced neurite extension. Likewise, EGF receptor down-regulation and the development of saxitoxin and tetanus toxin binding sites are either much reduced or completely absent in src-differentiated compared with NGF-differentiated PC12 cells.

Decreased levels of nerve growth factor receptor on dexamethasone-treated PC12 cells

Treatment of PC12 cells with dexamethasone leads, in a period of days, to a 60% decrease in the binding of (125I)nerve growth factor. The decrease was maximal after 3 days of treatment with 1 microM dexamethasone, but some decrease was seen after 6 hr and at concentrations as low as 10 nM. The effect was specific for the glucocorticosteroids. Scatchard plots confirmed the overall loss of nerve growth factor binding, and studies with trypsin digestion and Triton X-100 extraction indicated that the decrease in binding was largely due to a decrease in the number of low-affinity receptors. Nerve growth factor-induced changes, such as the induction of ornithine decarboxylase and the generation of neurites, were inhibited, but only minimally, in dexamethasone-treated cells.

Long-term, heterologous down-regulation of the epidermal growth factor receptor in PC12 cells by nerve growth factor

Cells of the rat pheochromocytoma clone PC12 possess receptors for both nerve growth factor (NGF) and epidermal growth factor (EGF), thus enabling the study of the interaction of these receptors in the regulation of proliferation and differentiation. Treatment of the cells with NGF induces a progressive and nearly total decrease in the specific binding of EGF beginning after 12 h and completed within 4 d. Three different measures of receptor show that the decreased binding capacity represents, in fact, a decreased amount of receptor: (a) affinity labeling of PC12 cell membranes by cross-linking of receptor-bound 125I-EGF showed a 60-90% decrease in the labeling of 170- and 150-kD receptor bands in cells treated with NGF for 1-4 d; (b) EGF-dependent phosphorylation of a src-related synthetic peptide or EGF receptor autophosphorylation with membranes from NGF-differentiated cells showed a decrease of 80 and 90% in the tyrosine kinase activity for the exogenous substrate and for receptor autophosphorylation, respectively; (c) analysis of 35S-labeled glycoproteins isolated by wheat germ agglutinin-Sepharose chromatography from detergent extracts of PC12 membranes showed a 70-90% decrease in the 170-kD band in NGF-differentiated cells. These findings permit the hypothesis that long-term heterologous down-regulation of EGF receptors by NGF in PC12 cells is mediated by an alteration in EGF receptor synthesis. It is suggested that this heterologous down-regulation is part of the mechanism by which differentiating cells become insensitive to mitogens.

A nerve growth factor-sensitive S6 kinase in cell-free extracts from PC12 cells

Soluble extracts from nerve growth factor (NGF)-stimulated PC12 cells prepared by alkaline lysis show a two- to 10-fold greater ability to phosphorylate the 40S ribosomal protein S6 than do extracts from control cells. The alkaline lysis method yields a preparation of much higher specific activity than does sonication. Half-maximal incorporation of 32P from [32P]ATP into S6 occurred after 4-7 min of NGF treatment. The partially purified NGF-sensitive S6 kinase has a molecular weight of 45,000. It is not inhibited by NaCl, chlorpromazine, or the specific inhibitor of cyclic AMP (cAMP)-dependent protein kinase, nor is it activated by addition of diolein plus phosphatidylserine. Trypsin treatment of either crude extracts or partially purified S6 kinase from control or NGF-treated cells was without effect. These data suggest that the S6 kinase stimulated by NGF is neither cAMP-dependent protein kinase or protein kinase C nor the result of tryptic activation of an inactive proenzyme. Treatment of intact cells with dibutyryl cAMP or 5'-N-ethylcarboxamideadenosine also increases the subsequent cell-free phosphorylation of S6. This observation suggests that cAMP-dependent protein kinase may be involved in the phosphorylation of S6 kinase.

The effect of fibroblast growth factor on PC12 cells

PC12 cells, which differentiate morphologically and biochemically into sympathetic neuron-like cells when treated with nerve growth factor, also respond to fibroblast growth factor. Some of the changes induced by fibroblast growth factor are similar to those seen after nerve growth factor treatment. Specifically, pituitary fibroblast growth factor causes the formation of processes initially comparable to those produced by nerve growth factor. However, in contrast to the outgrowth induced by nerve growth factor, which continues for several days, the outgrowth of processes induced by fibroblast growth factor ceases after about 3 days, even though fresh fibroblast growth factor is added. After about 6 days the processes induced by fibroblast growth factor have virtually disappeared. In this regard the processes induced by fibroblast growth factor are very similar to those induced by dibutyryl cyclic adenosine 3':5'-monophosphate (dBcAMP). The addition of nerve growth factor and fibroblast growth factor together appears to produce a synergistic effect on process formation, as does the simultaneous addition of nerve growth factor and dBcAMP. Cells pretreated (or primed) with nerve growth factor are able to regenerate processes much more rapidly in the presence of nerve growth factor than cells which have not been pretreated. When fibroblast growth factor is added to cells primed with nerve growth factor, more rapid regeneration of processes also occurs. The regeneration of neurites in response to either factor is blocked by the addition of an inhibitor of methylation. The process formation induced by fibroblast growth factor is preceded, as is the outgrowth in response to nerve growth factor treatment, by an induction of ornithine decarboxylase, a decrease in the phosphorylation of a specific cytoplasmic protein, and an increase in the phosphorylation of a specific non-histone nuclear protein. The effects of fibroblast growth factor and of nerve growth factor on ornithine decarboxylase are additive. Fibroblast growth factor does not cause an increase in the activity of acetylcholinesterase; nerve growth factor does. Fibroblast growth factor does not appear to be acting through the nerve growth factor receptor. The binding of iodinated nerve growth factor to PC12 cells is specific and is not inhibited by the presence of fibroblast growth factor. In addition, anti-nerve growth factor serum does not interfere with the action of fibroblast growth factor.(ABSTRACT TRUNCATED AT 400 WORDS)

The neurite-promoting effect of fibroblast growth factor on PC12 cells

Treatment of PC12 cells with fibroblast growth factor(s) from either brain or pituitary caused neurite outgrowth comparable to that produced by nerve growth factor. The neurite outgrowth was preceded by a substantial rise in the activity of ornithine decarboxylase.

The effects of nerve growth factor on polyamine metabolism in PC12 cells

Nerve growth factor treatment produces a large increase in the activity of ornithine decarboxylase and a moderate decrease in the activity of S-adenosylmethionine decarboxylase in PC12 cells. These changes are reflected weakly, if at all, in the levels of putrescine, spermidine, and spermine in the cells. The rates of polyamine synthesis are increased somewhat more than the overall levels, but still are not comparable in extent to the increase in the ornithine decarboxylase activity. Inhibitors of ornithine decarboxylase and S-adenosylmethionine decarboxylase have their expected effects on the induction of ornithine decarboxylase and on the activities of both enzymes. Neither inhibitor alone, nor a combination of inhibitors, altered the rate or extent of nerve growth factor-induced neurite outgrowth in the cells.

The action of adenosine analogs on PC12 cells

PC12 cells, a nerve growth factor-responsive clone of rat pheochromocytoma, contain a membrane-bound adenylate cyclase, which can be activated by adenosine analogs. The characteristics of the cyclase response indicate the presence of stimulatory adenosine receptors. Adenosine analogs also produce a marked increase in the ornithine decarboxylase levels of the cells, and the characteristics of this response suggest that it is linked to the adenylate cyclase-stimulatory adenosine receptors. The ornithine decarboxylase response elicited by 5'-N-ethylcarboxamideadenosine (NECA), a potent stimulatory adenosine analog, is synergistic with that produced by nerve growth factor. Differentiation of the cells with nerve growth factor, however, does not substantially alter either the response of cyclase to the adenosine analog or the magnitude of the adenosine-evoked ornithine decarboxylase response. Treatment of the cells with NECA produces an increase in the phosphorylation of a specific non-histone nuclear protein. While causing little or no morphological alteration by itself, NECA is synergistic with nerve growth factor in producing neurite outgrowth in PC12 cells. NECA does not cause an induction of acetylcholinesterase in the cells. NECA does not cause an induction of acetylcholinesterase in the cells, nor does it appear to affect the induction of this enzyme by nerve growth factor.

The induction of ornithine decarboxylase by nerve growth factor and epidermal growth factor in PC12 cells

Both nerve growth factor and epidermal growth factor cause an induction of ornithine decarboxylase in the rat pheochromocytoma clone PC12. The induction by nerve growth factor is transcription-dependent and occurs within 4 to 6 h. Antibody studies indicate that nerve growth factor must be present for 2-3 h to obtain full induction. Nerve growth factor is synergistic with either N6, O2-dibutyryl cyclic 3',5'-adenosine monophosphate (dBcAMP) or 3-isobutyl-1-methylxanthine (IBMX) in the induction. The magnitude of ornithine decarboxylase induction is influenced by the density of the culture. Synchronized cell populations show the greatest sensitivity to nerve growth factor just before, or immediately upon, entering S phase. The induction of ornithine decarboxylase by epidermal growth factor appears to be quite similar to that exhibited by nerve growth factor. Epidermal growth factor is active in the range of ng/ml. The time course of the induction is the same, as is the need for the peptide to remain in contact with the cells for several hours. Putrescine inhibits the induction and dBcAMP and IMBX accentuate it. Cells appear to be sensitive to epidermal growth factor also near the G1/S border. In spite of the marked similarities in these inductions, a maximal level of nerve growth factor plus a maximal level of epidermal growth factor yields greater induction than either alone, indicating the inductions occur by somewhat different mechanisms.

The receptor-mediated activation of tyrosine hydroxylation in the superior cervical ganglion of the rat

The addition of carbachol to superior cervical ganglia causes a rapid increase in tyrosine hydroxylation in situ. The increase occurs in ganglia from both newborn and adult animals, and in ganglia from animals pretreated with reserpine. The increase is not due to increased transport of the substrate. The increase is dependent upon the presence of calcium, and is additive to the stimulation produced by dibutyryl cyclic AMP. The stimulation seems specific for tyrosine hydroxylation; dopamine beta-hydroxylation is not increased. Preincubation experiments suggest that the carbachol-induced stimulation is due to a change in the availability of, or the affinity of the enzyme for, reduced pterin cofactor. The stimulation is inhibited by atropine and also by low concentrations of phenoxybenzamine or haloperidol, which suggests that it is caused by an action of carbachol on the interneurons in the ganglia.

Isolation and characterization of dihydropteridine reductase from Pseudomonas species

Dihydropteridine reductase isolated from the bacterium Pseudomonas species (ATCC 11299a) has been purified approximately 450-fold byammonium sulfate precipitation and diethylaminoethyl-cellulose chromatographic procedures. The preparation is at least 80% pure as judged by polyacrylamide gels. Its molecular weight was determined to be about 44,000. Both dihydropteridine reductase and phenylalanine hydroxylase activities were found to be higher in cells adapted to a medium containing L-phenylalanine or L-tyrosine as the sole carbon source than in those grown in L-asparagine. The substrate of the reductase is quinonoid dihydropteridine, and the product is tentatively identified as a tetrahydropteridine through its ability to serve as a cofactor for phenylalanine hydroxylase. The enzyme shows no marked specificity for the pteridine cofactor that occurs naturally in this organism, L-threo-neopterin. The pH optimum for the reductase is 7.2, and nicotinamide adenine dinucleotide, reduced form, is the preferred cosubstrate. Inhibition of the reduced and untreated enzyme by several sulfhydryl reagents was observed. A metal requirement for the reductase could not be demonstrated. Dihydropteridine reductase was found to be inhibited by aminopterin in a competitive manner with respect to the quinonoid dihydro form of 2-amino-4-hydroxy-6,7-dimethyl-5,6,7,8-tetrahydropteridine.