Natural language processing with machine learning methods to analyze unstructured patient-reported outcomes derived from electronic health records: A systematic review

OBJECTIVE

Natural language processing (NLP) combined with machine learning (ML) techniques are increasingly used to process unstructured/free-text patient-reported outcome (PRO) data available in electronic health records (EHRs). This systematic review summarizes the literature reporting NLP/ML systems/toolkits for analyzing PROs in clinical narratives of EHRs and discusses the future directions for the application of this modality in clinical care.

METHODS

We searched PubMed, Scopus, and Web of Science for studies written in English between 1/1/2000 and 12/31/2020. Seventy-nine studies meeting the eligibility criteria were included. We abstracted and summarized information related to the study purpose, patient population, type/source/amount of unstructured PRO data, linguistic features, and NLP systems/toolkits for processing unstructured PROs in EHRs.

RESULTS

Most of the studies used NLP/ML techniques to extract PROs from clinical narratives (n = 74) and mapped the extracted PROs into specific PRO domains for phenotyping or clustering purposes (n = 26). Some studies used NLP/ML to process PROs for predicting disease progression or onset of adverse events (n = 22) or developing/validating NLP/ML pipelines for analyzing unstructured PROs (n = 19). Studies used different linguistic features, including lexical, syntactic, semantic, and contextual features, to process unstructured PROs. Among the 25 NLP systems/toolkits we identified, 15 used rule-based NLP, 6 used hybrid NLP, and 4 used non-neural ML algorithms embedded in NLP.

CONCLUSIONS

This study supports the potential utility of different NLP/ML techniques in processing unstructured PROs available in EHRs for clinical care. Though using annotation rules for NLP/ML to analyze unstructured PROs is dominant, deploying novel neural ML-based methods is warranted.

Response-shift effects in childhood cancer survivors: A prospective study

BACKGROUND

Treatment-related late effects can worsen over time among cancer survivors. Such worsening health states may trigger changes in internal standards, values, or conceptualization of quality-of-life (QOL). This "response-shift" phenomenon can jeopardize the validity of QOL assessment, and misrepresent QOL comparisons over time. This study tested response-shift effects in reporting future-health concerns among childhood cancer survivors who experienced progression in chronic health conditions (CHCs).

METHODS

2310 adult survivors of childhood cancer from St. Jude Lifetime Cohort Study completed a survey and clinical assessment at two or more timepoints. Based on 190 individual CHCs graded for adverse-event severity, global CHC burden was classified as "progression" or "non-progression". QOL was assessed using the SF-36^TM eight domains and physical- and mental-component summary scores (PCS, MCS). A single global item measured concerns about future health. Random-effects models comparing survivors with and without progressive global CHC burden (progressors vs. non-progressors) evaluated response-shift effects (recalibration, reprioritization, reconceptualization) in reporting future-health concerns.

RESULTS

Compared with non-progressors, progressors were more likely to de-emphasize (or downplay) overall physical and mental health in evaluating future-health concerns (p-values<0.05), indicating recalibration response-shift, and more likely to de-emphasize physical health earlier rather than later in follow-up (p-value<0.05), indicating reprioritization response-shift. There was evidence for a reconceptualization response-shift with progressor classification associated with worse-than-expected future-health concerns and physical health, and better-than-expected pain and role-emotional functioning (p-values<0.05).

CONCLUSION

We identified three types of response-shift phenomena in reporting concerns about future health among childhood cancer survivors. Survivorship care or research should consider response-shift effects when interpreting changes in QOL over time.

Impact of COVID-19 on the End-of-Life Care of Cancer Patients Who Died in a Korean Tertiary Hospital: A Retrospective Study

Purpose

Social distancing and strict visitor restrictions at hospitals have been national policies since the onset of the coronavirus disease 2019 (COVID-19) pandemic. This has challenged the concept of a good death in comfort with the opportunity to say goodbye. Little is known about how these measures have influenced end-of-life (EOL) care among cancer patients who die in acute care hospitals. This study examined changes in the EOL care of cancer patients during the COVID-19 pandemic.

Methods

We retrospectively analyzed 1,456 adult cancer patients who died in 2019 (n=752) and 2020 (n=704) at a tertiary hospital. Data on EOL care-symptom control and comfort care in an imminently dying state, preparation for death, place of death, and aggressive care in the last month-were reviewed.

Results

The 1,456 patients had a median age of 67 years, and 62.5% were men. Patients who died in 2020 were more likely to experience agitation or delirium before death (17.2% vs. 10.9%), to use inotropes/vasopressors near death (59.2% vs. 52.3%), and to receive cardiopulmonary resuscitation in their last months (16.3% vs. 12.5%) than those who died in 2019. Additionally, the number of deaths in the emergency room doubled in 2020 compared to 2019 (from 7.1% to 14.1%).

Conclusion

This study suggests that EOL care for cancer patients who died in a tertiary hospital deteriorated during the COVID-19 pandemic. The implementation of medical care at the EOL and the preferred place of death should be discussed carefully in advance for high-quality EOL care.

Stronger association of perceived health with socio-economic inequality during COVID-19 pandemic than pre-pandemic era

Objective

The COVID-19 pandemic has changed peoples’ routine of daily living and posed major risks to global health and economy. Few studies have examined differential impacts of economic factors on health during pandemic compared to pre-pandemic. We aimed to compare the strength of associations between perceived health and socioeconomic position (household income, educational attainment, and employment) estimated before and during the pandemic.

Methods

Two waves of nationwide survey [on 2018(T1;n = 1200) and 2021(T2;n = 1000)] were done for 2200 community adults. A balanced distribution of confounders (demographics and socioeconomic position) were achieved across the T2 and T1 by use of the inverse probability of treatment weighting. Distributions of perceived health [= (excellent or very good)/(bad, fair, or good)] for physical-mental-social-spiritual subdomains were compared between T1 and T2. Odds of bad/fair/good health for demographics and socioeconomic position were obtained by univariate logistic regression. Adjusted odds (aOR) of bad/fair/good health in lower household income(< 3000 U.S. dollars/month) were retrieved using the multiple hierarchical logistic regression models of T1 and T2.

Results

Perceived health of excellent/very good at T2 was higher than T1 for physical(T1 = 36.05%, T2 = 39.13%; P = 0.04), but were lower for mental(T1 = 38.71%, T2 = 35.17%; P = 0.01) and social(T1 = 42.48%, T2 = 35.17%; P < 0.001) subdomains. Odds of bad/fair/good health were significantly increased at T2 than T1 for household income (physical-mental-social; all Ps < 0.001) and educational attainment (social; P = 0.04) but not for employment (all Ps > 0.05). AORs of bad/fair/good health in lower household income were stronger in T2 than T1, for mental [aOR (95% CI) = 2.15(1.68–2.77) in T2, 1.33(1.06–1.68) in T1; aOR difference = 0.82(P < 0.001)], physical [aOR (95% CI) = 2.64(2.05–3.41) in T2, 1.50(1.18–1.90) in T1; aOR difference = 1.14(P < 0.001)] and social [aOR (95% CI) = 2.15(1.68–2.77) in T2, 1.33(1.06–1.68) in T1; aOR difference = 0.35(P = 0.049)] subdomains.

Conclusions

Risks of perceived health worsening for mental and social subdomains in people with lower monthly household income or lower educational attainment became stronger during the COVID-19 pandemic compared to pre-pandemic era. In consideration of the prolonged pandemic as of mid-2022, policies aiming not only to sustain the monthly household income and compulsory education but also to actively enhance the perceived mental-social health status have to be executed and maintained.

The Impact of COVID-19 on Cancer Care in a Tertiary Hospital in Korea: Possible Collateral Damage to Emergency Care

Objectives

We investigated the impact of the COVID-19 pandemic on cancer care in a tertiary hospital of South Korea without the specific lockdown measures.

Methods

A retrospective cohort of cancer patients from one of the largest tertiary hospitals in South Korea was used to compare the healthcare utilization in different settings (outpatient clinic, emergency department (ED), and admission) between the period of January 1 and December 31, 2020 and the same time period in 2019. The percent changes in healthcare utilization between two periods were calculated.

Results

A total of 448,833 cases from the outpatient cohort, 26,781 cases from the ED cohort, and 14,513 cases from the admission cohort were reviewed for 2019 and 2020. The total number of ED visit cases significantly decreased in 2020 than in 2019 by 18.04%, whereas the proportion of cancer patients maintained. The reduction in ED visits was more prominent in cases with COVID-19 suspicious symptoms, with high acuity, and those who lived in non-capital city area. There were no significant changes in the number of total visits and new cases in the outpatient clinic between two periods. No significant differences in the total number of hospitalizations were observed between two periods.

Conclusion

During the pandemic, the number of ED visits significantly decreased, while the use of outpatient clinic and hospitalizations were not affected. Cancer patients' ED visits decreased after the COVID-19 outbreak, suggesting the potential for collateral damage outside the hospital if the ED could not be reached in a timely manner.

Attitudes toward the Legalization of Euthanasia or Physician-Assisted Suicide in South Korea: A Cross-Sectional Survey

This study aimed to investigate the general South Korean public attitudes toward the legalization of euthanasia or physician-assisted suicide (EAS) and examine the reasons underpinning these attitudes. From March–June 2021, we conducted a cross-sectional survey of a representative national sample of 1000 South Koreans aged 19 years or older. Three in four participants (76.4%) expressed positive attitudes toward the legalization of EAS. Participants who agreed with this legalization reported “meaninglessness of the rest of life” and “right to a good death” as their main reasons. Participants who disagreed with the legalization of EAS reported “respect for life”, “violation of the right to self-determination”, “risk of abuse or overuse”, and “violation of human rights” as theirs. In the multivariate logistic regression analyses, participants with poor physical status (adjusted odds ratio [aOR]: 1.41, 95%; confidence interval [CI]: 1.02–1.93) or comorbidity (aOR: 1.84, 95%; CI: 1.19–2.83) showed positive attitudes toward the legalization of EAS. In summary, most of the general South Korean population regards the legalization of EAS positively, especially participants with poor physical status or comorbidity.

Blood DNA methylation signatures are associated with social determinants of health among survivors of childhood cancer

Social epigenomics is an emerging field in which social scientist collaborate with computational biologists, especially epigeneticists, to address the underlying pathway for biological embedding of life experiences. This social epigenomics study included long-term childhood cancer survivors enrolled in the St. Jude Lifetime Cohort. DNA methylation (DNAm) data were generated using the Illumina EPIC BeadChip, and three social determinants of health (SDOH) factors were assessed: self-reported educational attainment, personal income, and an area deprivation index based on census track data. An epigenome-wide association study (EWAS) was performed to evaluate the relation between DNAm at each 5’-cytosine-phosphate-guanine-3’ (CpG) site and each SDOH factor based on multivariable linear regression models stratified by ancestry (European ancestry, n = 1,618; African ancestry, n = 258). EWAS among survivors of European ancestry identified 130 epigenome-wide significant SDOH–CpG associations (P < 9 × 10⁻⁸), 25 of which were validated in survivors of African ancestry (P < 0.05). Thirteen CpGs were associated with all three SDOH factors and resided at pleiotropic loci in cigarette smoking–related genes (e.g., CLDND1 and CPOX). After accounting for smoking and body mass index, these associations remained significant with attenuated effect sizes. Seven of 13 CpGs were associated with gene expression level based on 57 subsamples with blood RNA sequencing data available. In conclusion, DNAm signatures, many resembling the effect of tobacco use, were associated with SDOH factors among survivors of childhood cancer, thereby suggesting that biologically distal SDOH factors influence health behaviours or related factors, the epigenome, and subsequently survivors’ health.

The Association of the Health Management Strategy with Subjective Health and Well-being Outcomes in General Population

BACKGROUND

People face many obstacles to overcoming crisis in life and proactively manage life crises. This study aimed to evaluate the association of self-management strategy with subjective health and well-being for the general South Korean population.

METHODS

We recruited 1,200 respondents using an equal-probability sampling method from March to May 2018. A questionnaire including life version of the Smart Management Strategy for Health Assessment Tool (SAT-Life), the five Health Status Questionnaire, Short Form-12, McGill Quality of Life Questionnaire (MQOL), Patient Health Questionnaire-9 (PHQ-9), and Satisfaction With Life Scale (SWLS) was administered to participants.

RESULTS

In multiple stepwise logistic regression model adjusted with basic demographic variables (age, sex, region, education and monthly income level), core strategy was independently associated with physical, mental, social, spiritual, and general health status (adjusted odds ratios [aORs], 1.97-2.92). Preparation strategy was independently associated with physical, mental, spiritual, and general health status (aORs, 2.36-3.31). Implementation strategy was independently associated with physical, social, spiritual, and general health status (aORs, 2.22-2.42). Core strategy and implementation strategy were independently associated with higher Physical Component Score (aORs, 2.21-2.29) and higher Mental Component Score (aORs, 1.68-1.76). Core strategy and preparation strategy were independently associated with lower PHQ-9 (aORs, 2.63-3.74). Pearson's correlation coefficients between scores on SAT-Life and the other factors (MQOL social support, MQOL spiritual well-being, and SWLS) explain having significant correlations ranging from 0.41-0.43.

CONCLUSION

Self-management strategies of health might be encouraged to manage subjective health and well-being outcomes.

Natural Language Processing and Machine Learning Methods to Characterize Unstructured Patient-Reported Outcomes: Validation Study

BACKGROUND

Assessing patient-reported outcomes (PROs) through interviews or conversations during clinical encounters provides insightful information about survivorship.

OBJECTIVE

This study aims to test the validity of natural language processing (NLP) and machine learning (ML) algorithms in identifying different attributes of pain interference and fatigue symptoms experienced by child and adolescent survivors of cancer versus the judgment by PRO content experts as the gold standard to validate NLP/ML algorithms.

METHODS

This cross-sectional study focused on child and adolescent survivors of cancer, aged 8 to 17 years, and caregivers, from whom 391 meaning units in the pain interference domain and 423 in the fatigue domain were generated for analyses. Data were collected from the After Completion of Therapy Clinic at St. Jude Children's Research Hospital. Experienced pain interference and fatigue symptoms were reported through in-depth interviews. After verbatim transcription, analyzable sentences (ie, meaning units) were semantically labeled by 2 content experts for each attribute (physical, cognitive, social, or unclassified). Two NLP/ML methods were used to extract and validate the semantic features: bidirectional encoder representations from transformers (BERT) and Word2vec plus one of the ML methods, the support vector machine or extreme gradient boosting. Receiver operating characteristic and precision-recall curves were used to evaluate the accuracy and validity of the NLP/ML methods.

RESULTS

Compared with Word2vec/support vector machine and Word2vec/extreme gradient boosting, BERT demonstrated higher accuracy in both symptom domains, with 0.931 (95% CI 0.905-0.957) and 0.916 (95% CI 0.887-0.941) for problems with cognitive and social attributes on pain interference, respectively, and 0.929 (95% CI 0.903-0.953) and 0.917 (95% CI 0.891-0.943) for problems with cognitive and social attributes on fatigue, respectively. In addition, BERT yielded superior areas under the receiver operating characteristic curve for cognitive attributes on pain interference and fatigue domains (0.923, 95% CI 0.879-0.997; 0.948, 95% CI 0.922-0.979) and superior areas under the precision-recall curve for cognitive attributes on pain interference and fatigue domains (0.818, 95% CI 0.735-0.917; 0.855, 95% CI 0.791-0.930).

CONCLUSIONS

The BERT method performed better than the other methods. As an alternative to using standard PRO surveys, collecting unstructured PROs via interviews or conversations during clinical encounters and applying NLP/ML methods can facilitate PRO assessment in child and adolescent cancer survivors.

A network analysis of suicidal ideation, depressive symptoms, and subjective well-being in a community population

Although the relationship between subjective well-being (SWB) and suicidal ideation (SI) has been illustrated in previous research, few studies have conceptualized SWB as a comprehensive measure of life satisfaction in multiple domains, nor have they considered possible mediators such as depressive symptoms. Therefore, the present study aimed to identify dimensions of SWB correlated with SI, and to analyze associations among SWB sub-domains, depressive symptoms, and SI in a community population. A total of 1200 community adults in South Korea, aged 20-86 years, completed self-report questionnaires on demographics, depressive mood (Patient Health Questionnaire-9 [PHQ-9]), SI (item 9 of the PHQ-9), and 14 SWB sub-domains (Subjective Well-Being Inventory). Factors associated with SI, and interactions among SI, depressive mood, and SWB, were identified by logistic regression and phenotype network analyses, respectively. The five main factors influencing the regularized partial correlation network were life satisfaction, self-blame, job, hopelessness, and fatigue. Pathways were observed from work-life balance and life satisfaction to hopelessness; from self-blame and fatigue to safety and health; and from sleep disturbance, concentration difficulties, self-blame, and hopelessness to SI. Making job activities more emotionally rewarding, the potential for career progression and regular work hours could address anhedonia, hopelessness and sleep disturbance, respectively, thus enhancing SWB and reducing SI in the community population.

Development and validation of the Health-Friendly Activity Index: an assessment tool to comprehensively measure health-friendly activities of corporations or organisations

OBJECTIVES

We developed the Health-Friendly Activity Index (HFAI) to comprehensively measure the health-friendly activities of corporations or organisations. We validated the developed tool and reported on its use as an assessment tool to improve consumers' health-related outcomes.

DESIGN

This was a cross-sectional study.

SETTING

Development of the HFAI questionnaire followed a three-phase process: item generation, item construction and validation with field testing. Using relevance and feasibility criteria, we developed a 105-item questionnaire with six domains (Governance and Infrastructure, Needs Assessment, Planning, Implementation, Monitoring and Feedback, and Outcomes).

PARTICIPANTS

To assess the sensitivity and validity of the questionnaire, the HFAI and Contribution Assessment Tool for Consumer's Health (CATCH) were administered to 302 participants (151 employers and 151 employees) from 151 Korean companies.

PRIMARY OUTCOME MEASURES

The CATCH measured the contribution of each company to the physical, mental, social and spiritual health of its consumers. To estimate the reliability and validity of all six HFAI domains and their respective scales, Cronbach's α coefficients and correlation coefficients were used.

RESULTS

Each domain and scale of the HFAI exhibited a Cronbach's α coefficient between 0.80 and 0.98 for the employers and employees. The overall HFAI and its six domains correlated significantly and positively with all health outcomes such as physical, mental, social and spiritual status scores evaluated using the CATCH (Spearman's correlation range: 0.37-0.68).

CONCLUSION

The HFAI, a unique assessment tool with acceptable psychometric properties, can help corporate managers assess their health-friendly activities.

Persistent variations of blood DNA methylation associated with treatment exposures and risk for cardiometabolic outcomes in long-term survivors of childhood cancer in the St. Jude Lifetime Cohort

BACKGROUND

It is well-established that cancer treatment substantially increases the risk of long-term adverse health outcomes among childhood cancer survivors. However, there is limited research on the underlying mechanisms. To elucidate the pathophysiology and a possible causal pathway from treatment exposures to cardiometabolic conditions, we conducted epigenome-wide association studies (EWAS) to identify the DNA methylation (DNAm) sites associated with cancer treatment exposures and examined whether treatment-associated DNAm sites mediate associations between specific treatments and cardiometabolic conditions.

METHODS

We included 2052 survivors (median age 33.7 years) of European ancestry from the St. Jude Lifetime Cohort Study, a retrospective hospital-based study with prospective clinical follow-up. Cumulative doses of chemotherapy and region-specific radiation were abstracted from medical records. Seven cardiometabolic conditions were clinically assessed. DNAm profile was measured using MethylationEPIC BeadChip with blood-derived DNA.

RESULTS

By performing multiple treatment-specific EWAS, we identified 935 5'-cytosine-phosphate-guanine-3' (CpG) sites mapped to 538 genes/regions associated with one or more cancer treatments at the epigenome-wide significance level (p < 9 × 10-8). Among the treatment-associated CpGs, 8 were associated with obesity, 63 with hypercholesterolemia, and 17 with hypertriglyceridemia (false discovery rate-adjusted p < 0.05). We observed substantial mediation by methylation at four independent CpGs (cg06963130, cg21922478, cg22976567, cg07403981) for the association between abdominal field radiotherapy (abdominal-RT) and risk of hypercholesterolemia (70.3%) and by methylation at three CpGs (cg19634849, cg13552692, cg09853238) for the association between abdominal-RT and hypertriglyceridemia (54.6%). In addition, three CpGs (cg26572901, cg12715065, cg21163477) partially mediated the association between brain-RT and obesity with a 32.9% mediation effect, and two CpGs mediated the association between corticosteroids and obesity (cg22351187, 14.2%) and between brain-RT and hypertriglyceridemia (cg13360224, 10.5%). Notably, several mediator CpGs reside in the proximity of well-established dyslipidemia genes: cg21922478 (ITGA1) and cg22976567 (LMNA).

CONCLUSIONS

In childhood cancer survivors, cancer treatment exposures are associated with DNAm patterns present decades following the exposure. Treatment-associated DNAm sites may mediate the causal pathway from specific treatment exposures to certain cardiometabolic conditions, suggesting the utility of DNAm sites as risk predictors and potential mechanistic targets for future intervention studies.

Negligible Effects of the Survey Modes for Patient-Reported Outcomes: A Report From the Childhood Cancer Survivor Study

PURPOSE

This study compared the measurement properties for multiple modes of survey administration, including postal mail, telephone interview, and Web-based completion of patient-reported outcomes (PROs) among survivors of childhood cancer.

METHODS

The population included 6,974 adult survivors of childhood cancer in the Childhood Cancer Survivor Study who completed the Brief Symptom Inventory-18 (BSI-18), which measured anxiety, depression, and somatization symptoms. Scale reliability, construct validity, and known-groups validity related to health status were tested for each mode of completion. The multiple indicators and multiple causes technique was used to identify differential item functioning (DIF) for the BSI-18 items that responded through a specific survey mode. The impact of the administration mode was tested by comparing differences in BSI-18 scores between the modes accounting for DIF effects.

RESULTS

Of the respondents, 58%, 27%, and 15% completed postal mail, Web-based, and telephone surveys, respectively. Survivors who were male; had lower education, lower household income, or poorer health status; or were treated with cranial radiotherapy were more likely to complete a telephone-based survey compared with either a postal mail or Web-based survey (all P < .05). Scale reliability and validity were equivalent across the 3 survey options. One, 2, and 5 items from the anxiety, depression, and somatization domains, respectively, were identified as having significant DIF among survivors who responded by telephone (P < .05). However, estimated BSI-18 domain scores, especially depression and anxiety, between modes did not differ after accounting for DIF effects.

CONCLUSION

Certain survivor characteristics were associated with choosing a specific mode for PRO survey completion. However, measurement properties among these modes were equivalent, and the impact of using a specific mode on scores was minimal.

The major effects of health-related quality of life on 5-year survival prediction among lung cancer survivors: applications of machine learning

The primary goal of this study was to evaluate the major roles of health-related quality of life (HRQOL) in a 5-year lung cancer survival prediction model using machine learning techniques (MLTs). The predictive performances of the models were compared with data from 809 survivors who underwent lung cancer surgery. Each of the modeling technique was applied to two feature sets: feature set 1 included clinical and sociodemographic variables, and feature set 2 added HRQOL factors to the variables from feature set 1. One of each developed prediction model was trained with the decision tree (DT), logistic regression (LR), bagging, random forest (RF), and adaptive boosting (AdaBoost) methods, and then, the best algorithm for modeling was determined. The models' performances were compared using fivefold cross-validation. For feature set 1, there were no significant differences in model accuracies (ranging from 0.647 to 0.713). Among the models in feature set 2, the AdaBoost and RF models outperformed the other prognostic models [area under the curve (AUC) = 0.850, 0.898, 0.981, 0.966, and 0.949 for the DT, LR, bagging, RF and AdaBoost models, respectively] in the test set. Overall, 5-year disease-free lung cancer survival prediction models with MLTs that included HRQOL as well as clinical variables improved predictive performance.

Patient-reported outcomes in paediatric cancer survivorship: a qualitative study to elicit the content from cancer survivors and caregivers

OBJECTIVES

Content elucidation for patient-reported outcomes (PROs) in paediatric cancer survivorship is understudied. We aimed to compare differences in the contents of five PRO domains that are important to paediatric cancer survivorship through semistructured interviews with paediatric cancer survivors and caregivers, and identified new concepts that were not covered in the item banks of the Patient-Reported Outcomes Measurement Information System (PROMIS).

DESIGN

Semistructured interviews to collect qualitative PRO data from survivors and caregivers.

SETTING

A survivorship care clinic of a comprehensive cancer centre in the USA.

PARTICIPANTS

The study included 51 survivors (<18 years old) and 35 caregivers who completed interviews between August and December 2016. Content experts coded the transcribed interviews into 'meaningful concepts' per PROMIS item concepts and identified new concepts per a consensus. Frequencies of meaningful concepts used by survivors and caregivers were compared by Wilcoxon rank-sum test.

RESULTS

For pain and meaning and purpose, 'Hurt a lot' and 'Purpose in life' were top concepts for survivors and caregivers, respectively. For fatigue and psychological stress, 'Needed to sleep during the day'/'Trouble doing schoolwork' and 'Felt worried' were top concepts for survivors, and 'Felt tired' and 'Felt distress'/'Felt stressed' for caregivers. Survivors reported more physically relevant contents (eg, 'Hard to do sport/exercise'; 0.78 vs 0.23, p=0.007) for pain, fatigue and stress, whereas caregivers used more emotionally relevant concepts (eg, 'Too tired to enjoy things I like to do'; 0.31 vs 0.05, p=0.025). Both groups reported positive thoughts for meaning and purpose (eg, 'Have goals for myself'). One (psychological stress, meaning and purpose) to eleven (fatigue) new concepts were generated.

CONCLUSIONS

Important PRO contents in the form of meaningful concepts raised by survivors and caregivers were different and new concepts emerged. PRO measures are warranted to include survivorship-specific items by accounting for the child's and the caregiver's viewpoints.

Efficacy of an Electronic Health Management Program for Patients With Cardiovascular Risk: Randomized Controlled Trial

Background

In addition to medication, health behavior management is crucial in patients with multiple risks of cardiovascular mortality.

Objective

This study aimed to examine the efficacy of a 3-month Smart Management Strategy for Health–based electronic program (Smart Healthing).

Methods

A 2-arm randomized controlled trial was conducted to assess the efficacy of Smart Healthing in 106 patients with at least one indicator of poor disease control and who had hypertension, diabetes, or hypercholesterolemia. The intervention group (n=53) took part in the electronic program, which was available in the form of a mobile app and a Web-based PC application. The program covered 4 areas: self-assessment, self-planning, self-learning, and self-monitoring by automatic feedback. The control group (n=53) received basic educational material concerning disease control. The primary outcome was the percentage of participants who achieved their clinical indicator goal after 12 weeks into the program: glycated hemoglobin (HbA_1c) <7.0%, systolic blood pressure (SBP) <140 mmHg, or low-density lipoprotein cholesterol <130 mg/dL.

Results

The intervention group showed a significantly higher success rate (in comparison with the control group) for achieving each of 3 clinical indicators at the targeted goal levels (P<.05). Only the patients with hypertension showed a significant improvement in SBP from the baseline as compared with the control group (72.7% vs 35.7%; P<.05). There was a significant reduction in HbA_1c in the intervention group compared with the control group (difference=0.54%; P≤.05). In the intervention group, 20% of patients with diabetes exhibited a ≥1% decrease in HbA_1c (vs 0% among controls; P≤.05).

Conclusions

A short-term self-management strategy-based electronic program intervention may improve clinical outcomes among patients with cardiovascular risks.

Trial Registration

ClinicalTrials.gov NCT03294044; https://clinicaltrials.gov/ct2/show/NCT03294044

Efficacy of a Decision Aid Consisting of a Video and Booklet on Advance Care Planning for Advanced Cancer Patients: Randomized Controlled Trial

CONTEXT

Few randomized controlled trials of advance care planning (ACP) with a decision aid (DA) show an effect on patient preferences for end-of-life (EOL) care over time, especially in racial/ethnic settings outside the U.S.

OBJECTIVES

The objective of this study was to examine the effect of a decision aid consisting of a video and an ACP booklet for EOL care preferences among patients with advanced cancer.

METHODS

Using a computer-generated sequence, we randomly assigned (1:1) patients with advanced cancer to a group that received a video and workbook that both discussed either ACP (intervention group) or cancer pain control (control group). At baseline, immediately after intervention, and at 7 weeks, we evaluated the subjects' preferences. The primary outcome was preference for EOL care (active treatment, life-prolonging treatment, or hospice care) on the assumption of a fatal disease diagnosis and the expectation of death 1) within 1 year, 2) within several months, and 3) within a few weeks. We used Bonferroni correction methods for multiple comparisons with an adjusted P level of 0.005.

RESULTS

From August 2017 to February 2018, we screened 287 eligible patients, of whom 204 were enrolled to the intervention (104 patients) or the control (100 patients). At postintervention, the intervention group showed a significant increase in preference for active treatment, life-prolonging treatment, and hospice care on the assumption of a fatal disease diagnosis and the expectation of death within 1 year (P < 0.005). Assuming a life expectancy of several months, the change in preferences was significant for active treatment and hospice care (P < 0.005) but not for life-prolonging treatment. The intervention group showed a significant increase in preference for active treatment, life-prolonging treatment, and hospice care on the assumption of a fatal disease diagnosis and the expectation of death within a few weeks (P < 0.005). From baseline to 7 weeks, the decrease in preference in the intervention group was not significant for active treatment, life-prolonging treatment, and hospice care in the intervention group in the subset expecting to die within 1 year, compared with the control group. Assuming a life expectancy of several months and a few weeks, the change in preferences was not significant for active treatment and for life-prolonging treatment but was significantly greater for hospice care in the intervention group (P < 0.005).

CONCLUSION

ACP interventions that included a video and an accompanying book improved preferences for EOL care.

Predicting Disease-Free Lung Cancer Survival Using Patient Reported Outcome (PRO) Measurements with Comparisons of Five Machine Learning Techniques (MLT)

The study was to develop the lung cancer patients' prediction model for predicting 5-year survival after completion of treatment by using Machine Learning Technology (MLT), adding patient reporting (PRO) measurements of lung cancer survivors to a variety of clinical parameters. Finally, the survival prediction models with the addition of lung cancer survivors' PRO measurements to the well-known clinical variables, based on diverse MLT, improved the predictive performance that explains 5-year disease-free lung cancer survival.

Correction to: Priorities of a "good death" according to cancer patients, their family caregivers, physicians, and the general population: a nationwide survey

While recently extending that research, however, we discovered that 236 members of the general population were mistakenly duplicated by the investigating agency (Word Research) and 1241 were reported rather than 1005. Here, we present corrections and discuss the relevant data.

Development of the patient-reported outcomes (PRO) based survival prediction model for survivors who underwent lung cancer surgery

e23084

Background: To construct a prognostic model of 5-year survival among disease-free survivors who underwent lung cancer surgery using socio-clinical and patient-reported outcomes (PRO), and to compare its predictive performance with that of a traditional model based on known clinical variables. Methods: Data on 809 survivors who underwent lung cancer surgery between 2001 and 2006 in two Korean tertiary teaching hospitals were used. The training data set was utilized to generate the prediction model and the remaining 20% was employed as a testing set to estimate the model’s accuracy. Three Cox proportional hazard regression models were constructed and compared that of 5-year survival prediction ability through the evaluation of their performance in terms of discriminative and calibration ability. The three models were constructed with: 1) only clinical and socio-demographic variables, 2) only PROs, and 3) variables from model 1 and 2 considered altogether. The performance of each 5-year survival prediction model was evaluated using C-statistics and Hosmer-Lemeshow-type χ2-statistical analyses. Results: From the validation set, the C-statistics for the model 1, 2, and 3 were 0.70 (95% confidence interval [CI], 0.67−0.73), 0.77 (95% CI, 0.74−0.80), and 0.81 (95% CI, 0.78−0.84), respectively. In this study, model 3 (including PRO and other variables together) showed the highest discriminative and calibration ability compared to others. Conclusions: The findings suggested that the PRO included model in addition to clinical and socio-demographic variables, is more accurate in the survival prediction of lung cancer survivors than models constructed with only well-known socio-clinical variables.

The Satisfaction with Life Scale and the Subjective Well-Being Inventory in the General Korean Population: Psychometric Properties and Normative Data

This study aims to evaluate the psychometric properties of the Satisfaction with Life Scale (SWLS) and the Subjective Well-Being Inventory (SWBI) in a nationally representative sample in Korea. A total of 1200 people completed the semi-structured, self-reported questionnaire, which included five items from the SWLS and 14 items from the SWBI. All items and the total score of both the SWLS and the SWBI showed high internal consistency (with Cronbach’s alphas of 0.886 and 0.946, respectively). The item-total correlation values for both measures were in the ranges of 0.71–0.75 and 0.65–0.80, respectively. There were positive correlations between the SWLS and SWBI (r = 0.59, p = 0.01). The SWLS, SWBI and global well-being (GWB) scores were positively correlated with the McGill Quality of Life subscales (p = 0.01) but negatively correlated with the Patient Health Questionnaire-9 (p = 0.01). Participants under 50 years old (adjusted odds ratio [aOR] = 1.30, 95% confidence interval [CI] = 1.00–1.69) and those in rural areas (aOR = 1.63, 95% CI = 1.28–2.07) had higher scores on the SWLS than other participant groups. Participants who were under 50 years old (aOR = 1.47, 95% CI = 1.12–1.92), were male (aOR = 1.33, 95% CI = 1.04–1.71), were married (aOR = 1.51, 95% CI = 1.13–2.01), lived in rural areas (aOR = 2.30, 95% CI = 1.35–3.91), or had higher incomes (aOR = 1.30, 95% CI = 1.02–1.65) showed higher SWBI scores. This study showed that the SLWS and SWBI have good psychometric properties and could be applicable to Korea.

Attitudes of the General Public, Cancer Patients, Family Caregivers, and Physicians Toward Advance Care Planning: A Nationwide Survey Before the Enforcement of the Life-Sustaining Treatment Decision-Making Act

CONTEXT

To respect a patient's wish for end-of-life care, "the Act on Decisions on Life-Sustaining Treatment for Patients at the End-of-Life" was enacted in South Korea in 2016. Current understanding of people who would be involved in advance care planning (ACP) is crucial to disseminate it systematically.

OBJECTIVES

The objective of this study was to investigate awareness and attitudes toward ACP in South Korea.

METHODS

A multicenter, nationwide cross-sectional study was conducted, a survey regarding ACP among four groups that would have different positions and experiences: 1001 cancer patients, 1006 family caregivers, 928 physicians, and 1241 members of the general public.

RESULTS

A total of 15% of the general population, 33% of the patients and caregivers, and 61% of the physicians had knowledge of advance directives. More than 64% of the general population, above 72% of the patients and caregivers, and 97% of the physicians were willing to do so when the disease status was aggravated or terminal. The possibility for changing the plan, uncertainty as to whether directives would actually be followed, and psychological discomfort were common reasons for not wanting to engage in ACP. Routine recommendations for a specific medical condition, heightened accessibility, and health insurance support were common factors that could help facilitate ACP.

CONCLUSION

Our findings suggest that strategies for promoting ACP should reflect different perspectives among the general public, patients, family caregivers, and physicians. Public advocacy, resources for approaching and integrating ACP into routine health care, as well as systematic support provisions are needed.

Establishment of Normative Self-Rated Health Status Data and Association between Ideal Life Expectancy and Social Wellness of General Population in Korea

PURPOSE

The purpose of this study was to establish normative data for holistic health parameters in the general Korean population and to investigate the factor associated with ideal life expectancy (ILE) among these holistic health parameters and sociodemographic variables.

METHODS

This study used a questionnaire to obtain self-reported physical, mental, social, spiritual, and general health status and then evaluated their association with ILE. A total of 1,241 individuals responded to the questionnaire, from which we established a multidimensional health status reference data set representing the Korean population. To explain factors associated with ILE, we stratified results by age and gender and performed multiple logistic regression of sociodemographic variables and multidimensional health status.

RESULTS

Women reported poor health status more frequently for all five health categories. The average ILE was 87.46 years versus 84.42 years of life expectancy in the general Korean population. Single marital status, higher income, and better social health were significantly associated with higher ILE.

CONCLUSION

ILE could be a good indicator reflecting social wellness in a certain society. Comprehensive social health promotion programs can improve individuals' attitudes toward life expectancy, especially for vulnerable groups.

Erratum: Correction of Ethics Statement: Discordance between Physician and the General Public Perceptions of Prognostic Disclosure to Children with Serious Illness: a Korean Nationwide Study

[This corrects the article e327 in vol. 33, PMID: 30505258.].

Discordance between Physician and the General Public Perceptions of Prognostic Disclosure to Children with Serious Illness: a Korean Nationwide Study

BACKGROUND

It is difficult to decide whether to inform the child of the incurable illness. We investigated attitudes of the general population and physicians toward prognosis disclosure to children and associated factors in Korea.

METHODS

Physicians working in one of 13 university hospitals or the National Cancer Center and members of the general public responded to the questionnaire. The questionnaire consisted of the age appropriate for informing children about the prognosis and the reason why children should not be informed. This survey was conducted as part of research to identify perceptions of physicians and general public on the end-of-life care in Korea.

RESULTS

A total of 928 physicians and 1,241 members of the general public in Korea completed the questionnaire. Whereas 92.7% of physicians said that children should be informed of their incurable illness, only 50.7% of the general population agreed. Physicians were also more likely to think that younger children should know about their poor prognosis compared with the general population. Physicians who opposed incurable illness disclosure suggested that children might not understand the situation, whereas the general public was primarily concerned that disclosure would exacerbate the disease. Physicians who were women or religious were more likely to want to inform children of their poor prognosis. In the general population, gender, education, comorbidity, and caregiver experience were related to attitude toward poor prognosis disclosure to children.

CONCLUSION

Our findings indicate that physicians and the general public in Korea differ in their perceptions about informing children of poor prognosis.

Comparison of attitudes towards five end-of-life care interventions (active pain control, withdrawal of futile life-sustaining treatment, passive euthanasia, active euthanasia and physician-assisted suicide): a multicentred cross-sectional survey of Korean patients with cancer, their family caregivers, physicians and the general Korean population

OBJECTIVES

This study determined attitudes of four groups-Korean patients with cancer, their family caregivers, physicians and the general Korean population-towards five critical end-of-life (EOL) interventions-active pain control, withdrawal of futile life-sustaining treatment (LST), passive euthanasia, active euthanasia and physician-assisted suicide.

DESIGN AND SETTING

We enrolled 1001 patients with cancer and 1006 caregivers from 12 large hospitals in Korea, 1241 members of the general population and 928 physicians from each of the 12 hospitals and the Korean Medical Association. We analysed the associations of demographic factors, attitudes towards death and the important components of a 'good death' with critical interventions at EoL care.

RESULTS

All participant groups strongly favoured active pain control and withdrawal of futile LST but differed in attitudes towards the other four EoL interventions. Physicians (98.9%) favoured passive euthanasia more than the other three groups. Lower proportions of the four groups favoured active euthanasia or PAS. Multiple logistic regression showed that education (adjusted OR (aOR) 1.77, 95% CI 1.33 to 2.36), caregiver role (aOR 1.67, 95% CI 1.34 to 2.08) and considering death as the ending of life (aOR 1.66, 95% CI 1.05 to 1.61) were associated with preference for active pain control. Attitudes towards death, including belief in being remembered (aOR 2.03, 95% CI 1.48 to 2.79) and feeling 'life was meaningful' (aOR 2.56, 95% CI 1.58 to 4.15) were both strong correlates of withdrawal of LST with the level of monthly income (aOR 2.56, 95% CI 1.58 to 4.15). Believing 'freedom from pain' negatively predicted preference for passive euthanasia (aOR 0.69, 95% CI 0.55 to 0.85). In addition, 'not being a burden to the family' was positively related to preferences for active euthanasia (aOR 1.62, 95% CI 1.39 to 1.90) and PAS (aOR 1.61, 95% CI 1.37 to 1.89).

CONCLUSION

Groups differed in their attitudes towards the five EoL interventions, and those attitudes were significantly associated with various attitudes towards death.

Priorities of a "good death" according to cancer patients, their family caregivers, physicians, and the general population: a nationwide survey

PURPOSE

Understanding the concept of a "good death" is crucial to end-of-life care, but our current understanding of what constitutes a good death is insufficient. Here, we investigated the components of a good death that are important to the general population, cancer patients, their families, and physicians.

METHODS

We conducted a stratified nationwide cross-sectional survey of cancer patients and their families from 12 hospitals, physicians from 12 hospitals and the Korean Medical Association, and the general population, investigating their attitudes toward 10 good-death components.

FINDINGS

Three components-"not be a burden to the family," "presence of family," and "resolve unfinished business"-were considered the most important components by more than 2/3 of each of the three groups, and an additional three components-"freedom from pain," "feel that life was meaningful," and "at peace with God"-were considered important by all but the physicians group. Physicians considered "feel life was meaningful," "presence of family," and "not be a burden to family" as the core components of a good death, with "freedom from pain" as an additional component. "Treatment choices' followed, "finances in order," "mentally aware," and "die at home" were found to be the least important components among all four groups.

CONCLUSION

While families strongly agreed that "presence of family" and "not be a burden to family" were important to a good death, the importance of other factors differed between the groups. Health care providers should attempt to discern each patient's view of a good death.

Development and validation of the quality care questionnaire -palliative care (QCQ-PC): patient-reported assessment of quality of palliative care

BACKGROUND

In this study, we aimed to develop and validate an instrument that could be used by patients with cancer to evaluate their quality of palliative care.

METHODS

Development of the questionnaire followed the four-phase process: item generation and reduction, construction, pilot testing, and field testing. Based on the literature, we constructed a list of items for the quality of palliative care from 104 quality care issues divided into 14 subscales. We constructed scales of 43 items that only the cancer patients were asked to answer. Using relevance and feasibility criteria and pilot testing, we developed a 44-item questionnaire. To assess the sensitivity and validity of the questionnaire, we recruited 220 patients over 18 years of age from three Korean hospitals.

RESULTS

Factor analysis of the data and fit statistics process resulted in the 4-factor, 32-item Quality Care Questionnaire-Palliative Care (QCQ-PC), which covers appropriate communication with health care professionals (ten items), discussing value of life and goals of care (nine items), support and counseling for needs of holistic care (seven items), and accessibility and sustainability of care (six items). All subscales and total scores showed a high internal consistency (Cronbach alpha range, 0.89 to 0.97). Multi-trait scaling analysis showed good convergent (0.568-0.995) and discriminant (0.472-0.869) validity. The correlation between the total and subscale scores of QCQ-PC and those of EORTC QLQ-C15-PAL, MQOL, SAT-SF, and DCS was obtained.

CONCLUSION

This study demonstrates that the QCQ-PC can be adopted to assess the quality of care in patients with cancer.

Association between information provision and decisional conflict in cancer patients

BACKGROUND

In this study, we aimed to identify demographic and clinical variables that correlate with perceived information provision among cancer patients and determine the association of information provision with decisional conflict (DC).

PATIENTS AND METHODS

We enrolled a total of 625 patients with cancer from two Korean hospitals in 2012. We used the European Organization for Research and Treatment of Cancer (EORTC) quality-of-life questionnaire (QLQ-INFO26) to assess patients' perception of the information received from their doctors and the Decisional Conflict Scale (DCS) to assess DC. To identify predictive sociodemographic and clinical variables for adequate information provision, backward selective logistic regression analyses were conducted. In addition, adjusted multivariate logistic regression analyses were carried out to identify clinically meaningful differences of perceived level of information subscales associated with high DC.

RESULTS

More than half of patients with cancer showed insufficient satisfaction with medical information about disease (56%), treatment (73%), other services (83%), and global score (80%). In multiple logistic regression analyses, lower income and education, female, unmarried status, type of cancer with good prognosis, and early stage of treatment process were associated with patients' perception of inadequate information provision. In addition, Information about the medical tests with high DCS values clarity [adjusted odds ratio (aOR), 0.54; 95% confidence interval (CI) 0.30-0.97] and support (aOR, 0.53; 95% CI 0.33-0.85) showed negative significance. For inadequate information perception about treatments and other services, all 5 DCS scales (uncertainty, informed, values clarity, support, and effective decision) were negatively related. Global score of inadequate information provision also showed negative association with high DCS effective decision (aOR, 0.43; 95% CI 0.26-0.71) and DCS uncertainty (aOR, 0.46; 95% CI 0.27-0.77).

CONCLUSION

This study found that inadequate levels of perceived information correlated with several demographic and clinical characteristics. In addition, sufficient perceived information levels may be related to low levels of DC.

Effect of the intra-abdominal pressure and the center of segmental body mass on the lumbar spine mechanics - a computational parametric study

Determination of physiological loads in human lumbar spine is critical for understanding the mechanisms of lumbar diseases and for designing surgical treatments. Computational models have been used widely to estimate the physiological loads of the spine during simulated functional activities. However, various assumptions on physiological factors such as the intra-abdominal pressure (IAP), centers of mass (COMs) of the upper body and lumbar segments, and vertebral centers of rotation (CORs) have been made in modeling techniques. Systematic knowledge of how these assumptions will affect the predicted spinal biomechanics is important for improving the simulation accuracy. In this paper, we developed a 3D subject-specific numerical model of the lumbosacral spine including T12 and 90 muscles. The effects of the IAP magnitude and COMs locations on the COR of each motion segment and on the joint/muscle forces were investigated using a global convergence optimization procedure when the subject was in a weight bearing standing position. The data indicated that the line connecting the CORs showed a smaller curvature than the lordosis of the lumbar spine in standing posture when the IAP was 0 kPa and the COMs were 10 mm anterior to the geometric center of the T12 vertebra. Increasing the IAP from 0 kPa to 10 kPa shifted the location of CORs toward the posterior direction (from 1.4 ± 8.9 mm anterior to intervertebral disc (IVD) centers to 40.5 ± 3.1 mm posterior to the IVD centers) and reduced the average joint force (from 0.78 ± 0.11 Body weight (BW) to 0.31 ± 0.07 BW) and overall muscle force (from 349.3 ± 57.7 N to 221.5 ± 84.2 N). Anterior movement of the COMs from -30 mm to 70 mm relative to the geometric center of T12 vertebra caused an anterior shift of the CORs (from 25.1 ± 8.3 mm posterior to IVD centers to 7.8 ± 6.2 mm anterior to IVD centers) and increases of average joint forces (from 0.78 ± 0.1 BW to 0.93 ± 0.1 BW) and muscle force (from 348.9 ± 47.7 N to 452.9 ± 58.6 N). Therefore, it is important to consider the IAP and correct COMs in order to accurately simulate human spine biomechanics. The method and results of this study could be useful for designing prevention strategies of spinal injuries and recurrences, and for enhancing rehabilitation efficiency.

'Out of two bad choices, I took the slightly better one': vaccination dilemmas for Scottish and Polish migrant women during the H1N1 influenza pandemic

OBJECTIVES

Pregnancy has been identified as a risk factor for complications from pandemic H1N1 influenza, and pregnant women were identified as a target group for vaccination in the UK in the 2009 pandemic. Poland took a more conservative approach, and did not offer vaccination to pregnant women. Poland accounts for the largest wave of recent migrants to the UK, many of whom are in their reproductive years and continue to participate actively in Polish healthcare systems after migration. The authors speculated that different national responses may shape differences in approaches to the vaccine between Scottish and Polish women. This study therefore aimed to assess how pregnant Polish migrants to Scotland weighed up the risks and benefits of the vaccine for pandemic H1N1 influenza in comparison with their Scottish counterparts.

STUDY DESIGN

A qualitative interview-based study comparing the views of Scottish and Polish pregnant women on H1N1 vaccination was carried out in 'real time' during the first 2 weeks of the vaccination programme in November 2009.

METHODS

One-to-one interviews were conducted with 10 women (five Polish and five Scottish) in their native language. Interviews were transcribed, translated, coded and analysed for differences and similarities in decision-making processes between the two groups.

RESULTS

Contrary to expectations, Scottish and Polish women drew on a strikingly similar set of considerations in deciding whether or not to accept the vaccine, with individual women reaching different conclusions. Almost all of the women adopted a critical stance towards the vaccine. While most women understood that pregnancy was a risk factor for complications from influenza, their primary concern was protecting family health overall and their fetus in particular. Deciding whether or not to accept the vaccine was difficult for women. Some identified a contradiction between the culture of caution which characterizes pregnancy-related advice, and the fact that they were being urged to accept what was perceived as a relatively untested vaccine. Their health histories, individual constitutions, and whether their everyday routines exposed them to sources of infection combined to establish their perceived 'candidacy' for contracting infection. Neither Scottish nor Polish women felt that 'official' information addressed their concerns in sufficient detail, and almost all of the women sought information from a variety of sources. Polish women found it more difficult to access information and advice from the National Health Service than their Scottish counterparts. For most respondents, deciding whether or not to accept the vaccine was an attenuated process, culminating for many in choosing the 'least worst' option in the context of competing risks.

CONCLUSIONS

To the authors' knowledge, this is the first study to assess perceptions of H1N1 immunization risk in pregnant women in 'real time'. It highlights the important unmet needs for information that women need to be able to make informed vaccination choices, and the challenges of producing such information in a context of uncertainty. This is of particular relevance as many countries, including the UK, are actively reviewing their plans for vaccination programmes during pregnancy.

Amitriptyline does not block the action of ATP at human P2X4 receptor

BACKGROUND AND PURPOSE

Amitriptyline is a tricyclic antidepressant that is also widely used to treat neuropathic pain in humans, but the mechanism of this anti-hyperalgesic effect is unknown. Microglia in the mouse spinal cord become activated in neuropathic pain, and expression of P2X4 receptors by these microglia is increased. Antisense RNA targeting P2X4 receptors suppresses the development of tactile allodynia in rats. This suggests that blockade of P2X4 receptors might be the mechanism by which amitriptyline relieves neuropathic pain.

EXPERIMENTAL APPROACH

We expressed human, rat and mouse P2X receptors (P2X2, P2X4, P2X7) in human embryonic kidney cells and evoked inward currents by applying ATP. We compared the action of ATP on control cells and cells treated with amitriptyline.

KEY RESULTS

Amitriptyline (10 microM), either applied acutely or by pre-incubation for 2-6 h, had no effect on inward currents evoked by ATP (0.3-100 microM) at human P2X4 receptors. At rat and mouse receptors, amitriptyline (10 microM) caused a modest reduction in the maximum responses to ATP, without changes in EC(50) values, but it had no effect at 1 microM. Amitriptyline also had no effects on currents evoked by ATP at rat P2X2 receptors, or at rat or human P2X7 receptors.

CONCLUSION AND IMPLICATIONS

The results do not support the view that amitriptyline owes its pain-relieving actions in man to the direct blockade of P2X4 receptors.

P2X1 and P2X4 receptor currents in mouse macrophages

BACKGROUND AND PURPOSE

Activation of P2X receptors on macrophages is an important stimulus for cytokine release. This study seeks evidence for functional expression of P2X receptors in macrophages that had been only minimally activated.

EXPERIMENTAL APPROACH

Whole-cell recordings were made from macrophages isolated 2-6 h before by lavage from mouse peritoneum, without further experimental activation. ATP (1-1000 muM) elicited inward currents in all cells (holding potential -60 mV). The properties of this current were compared among cells from wild type, P2X1 (-/-) and P2X4 (-/-) mice.

KEY RESULTS

Immunoreactivity for P2X1 and P2X4 receptors was observed in wild type macrophages but was absent from the respective knock-out mice. In cells from wild type mice, ATP and alpha beta methyleneATP (alpha beta meATP) evoked inward currents rising in 10-30 ms and declining in 100-300 ms: these were blocked by pyridoxal-phosphate-6-azophenyl-2',4'-disulphonic acid (PPADS, 10 microM). ATP also elicited a second, smaller ( approximately 10% peak amplitude), more slowly decaying (1-3 s) at concentrations > or =10 microM: this was resistant to PPADS and prolonged by ivermectin. Macrophages from P2X1 (-/-) mice responded to ATP (>100 microM) but not alpha beta meATP: these small currents were prolonged by ivermectin. Macrophages from P2X4 (-/-) mice responded to ATP and alpha beta meATP as cells from wild type mice, except that ATP did not evoke the small, slowly decaying component: these currents were blocked by PPADS.

CONCLUSION

Mouse peritoneal macrophages that are minimally activated demonstrate membrane currents in response to ATP and alpha beta meATP that have the predominate features of P2X1 receptors.

Molecular and cellular properties of GnRH neurons revealed through transgenics in the mouse

Recent advances in the use of gonadotropin-releasing hormone (GnRH) promoter-driven transgenics in the mouse are beginning to open up the once elusive GnRH neuronal phenotype to detailed molecular and cellular investigation. This review highlights progress in the development of GnRH promoter transgenic constructs and the understanding of murine gene sequences required for the correct temporal and spatial targeting of transgenes to the GnRH phenotype in vivo. Strategies enabling the identification of single, living GnRH neurons in the acute brain slice preparation are allowing gene profiling and electrophysiological experiments to be undertaken. Results so far indicate that, like other neurons, GnRH cells express a variety of sodium, potassium and calcium channels as well as GABAergic and glutamatergic receptors which are responsible for determining the membrane properties and firing characteristics of the GnRH neuron. Many of these receptors and channels appear to be expressed heterogeneously within the GnRH phenotype. Furthermore, several display distinct postnatal developmental expression profiles which are likely to be of consequence to the development of synchronized, pulsatile GnRH secretion in the adult animal.

Profiling gamma-aminobutyric acid (GABA(A)) receptor subunit mRNA expression in postnatal gonadotropin-releasing hormone (GnRH) neurons of the male mouse with single cell RT-PCR

The present investigation has examined which subunits of the GABA(A) receptor are expressed by gonadotropin-releasing hormone (GnRH) neurons in the juvenile and adult male mouse. Cells of defined morphology, located in the medial septum (MS) and rostral preoptic area (POA), were patch-clamped in the acute brain slice preparation and their cell contents extracted. A reverse transcriptase polymerase chain reaction (RT-PCR) procedure using nested primers was used to establish individual GnRH mRNA-expressing cells which were then evaluated for eleven GABA(A) receptor (alpha1-5, beta1-3, gamma1-3) subunit transcripts. Single and multiple GABA(A) receptor subunit mRNAs were detected in approximately 70% of all GnRH neurons. A range of different subunit mRNAs (alpha1, alpha2, alpha5, beta1, beta2, beta3, gamma2) were found in juvenile GnRH neurons, with the alpha1gamma2 and alpha5gamma2 combinations encountered most frequently within individual cells. The expression profile in adult GnRH neurons was more extensive than that detected in juveniles with alpha1, alpha2, alpha3, alpha5, beta1, beta2, beta3, gamma1 and gamma2 subunits all being detected. The major difference in subunit profile between GnRH neurons located in the MS and POA involved the beta subunits. The principal postnatal developmental change was one of increasing overall subunit heterogeneity in maturing POA GnRH neurons. The profile of GABA(A) receptor subunit mRNAs detected in male GnRH neurons was quite different to that reported by us for female GnRH neurons in the mouse using the same RT-PCR approach. Together, these findings indicate that postnatal GnRH neurons are likely to express a range of GABA(A) receptor subunit mRNAs in a sexually dimorphic and developmentally-regulated manner.

Direct regulation of postnatal GnRH neurons by the progesterone derivative allopregnanolone in the mouse

The mechanisms through which gonadal steroids exert critical feedback actions upon the activity of the GnRH neurons are not understood. We have examined here whether progesterone may modulate the electrical activity of the GnRH neurons following its rapid metabolism to the neuroactive steroid allopregnanolone within the brain. Using an acute brain slice preparation, whole-cell, patch-clamp recordings were made from GnRH neurons of juvenile (postnatal d 15-20) and adult (postnatal d 60-70) female mice in the presence of tetrodotoxin. Progesterone (1 microM) was not observed to have any actions (up to 5 min exposure) upon GnRH neurons. However, allopregnanolone (500 nM-1 microM) exerted rapid (<1 min) effects upon the baseline membrane potential of all GnRH neurons and also significantly (P < 0.01) enhanced their GABA responses by up to 4-fold. All GABA and allopregnanolone responses were abolished by the GABA(A) receptor antagonist bicuculline. No differences were detected in the allopregnanolone sensitivity of GnRH neurons recorded from juvenile and adult GnRH neurons. These results provide the first evidence for a direct action of the neurosteroid allopregnanolone on postnatal GnRH neurons and suggest a new mechanism through which fluctuating progesterone levels may influence the secretory activity of these important neurons in the female mouse.

Heterogeneity in the basic membrane properties of postnatal gonadotropin-releasing hormone neurons in the mouse

The electrophysiological characteristics of unmodified, postnatal gonadotropin-releasing hormone (GnRH) neurons in the female mouse were studied using whole-cell recordings and single-cell RT-PCR methodology. The GnRH neurons of adult animals fired action potentials and exhibited distinguishable voltage-current relationships in response to hyperpolarizing and depolarizing current injections. On the basis of their patterns of inward rectification, rebound depolarization, and ability to fire repetitively, GnRH neurons in intact adult females were categorized into four cell types (type I, 48%; type II, 36%; type III, 11%; type IV, 5%). The GnRH neurons of juvenile animals (15-22 d) exhibited passive membrane properties similar to those of adult GnRH neurons, although only type I (61%) and type II (7%) cells were encountered, in addition to a group of "silent-type" GnRH neurons (32%) that were unable to fire action potentials. A massive, action potential-independent tonic GABA input, signaling through the GABA(A) receptor, was present at all ages. Afterdepolarization and afterhyperpolarization potentials (AHPs) were observed after single action potentials in subpopulations of each GnRH neuron type. Tetrodotoxin (TTX)-independent calcium spikes, as well as AHPs, were encountered more frequently in juvenile GnRH neurons compared with adults. These observations demonstrate the existence of multiple layers of functional heterogeneity in the firing properties of GnRH neurons. Together with pharmacological experiments, these findings suggest that potassium and calcium channels are expressed in a differential manner within the GnRH phenotype. This heterogeneity occurs in a development-specific manner and may underlie the functional maturation and diversity of this unique neuronal phenotype.

Late postnatal reorganization of GABA(A) receptor signalling in native GnRH neurons

The molecular and cellular characteristics of the gonadotropin-releasing hormone (GnRH) neurons have been difficult to ascertain due to their scattered distribution within the basal forebrain. Using morphological criteria coupled with single cell RT-PCR postidentification, we have developed a method for investigating native GnRH neurons in the mouse brain and used it to examine the development of GABA(A) receptor signalling in this phenotype. Following the harvesting of the cytoplasmic contents of individual GnRH neurons, single cell multiplex RT-PCR experiments demonstrated that GABAA receptor alpha1-5, beta1-3 and gamma2 & 3 subunit transcripts were expressed by both neonatal (postnatal day 5) and juvenile (day 15-20) GnRH neurons in a heterogeneous manner. Following puberty, this profile was reduced to a predominant alpha1, alpha5, beta1, gamma2 subunit complement in rostral preoptic area GnRH neurons of the adult female. Whole-cell patch-clamp recordings revealed little difference between juvenile and adult GnRH neurons in their resting membrane potential and spontaneous firing rates. All GnRH neurons were found to be subjected to a tetrodotoxin-insensitive, tonic GABAergic barrage signalling through the GABA(A) receptor. However, marked heterogeneity in the sensitivity of individual juvenile GnRH neurons to GABA was revealed and, in parallel with the change in subunit mRNA profile, this was dramatically reduced in the reproductively competent adult GnRH neurons. These findings provide the first electrical and molecular characterization of the GnRH phenotype and demonstrate a novel pattern of late postnatal reorganization of native GABA(A) receptor gene expression and signalling in the GnRH neuronal population.

Detection of estrogen receptor alpha and beta messenger ribonucleic acids in adult gonadotropin-releasing hormone neurons

The behavior of the gonadotropin-releasing hormones (GnRH) neurons controlling fertility is dependent upon cyclic fluctuations in circulating concentrations of estrogen. However, the nature of estrogen action upon these cells has remained controversial due to their dispersed distribution within the brain, and evidence indicating that they do not express nuclear estrogen receptors (ERs) in vivo. We report here an acute brain slice preparation that enables individual living GnRH neurons to be identified within the mouse brain and show, using single cell multiplex RT-PCR, that the greater than 50% of GnRH neurons in adult and prepubertal females contain ERalpha messenger RNA. Approximately 10% of GnRH neurons contained ERbeta transcripts that were always coexistent with ERalpha. Single cell RT-PCR analysis of nonGnRH cells located in the medial preoptic area revealed a similar coexpression pattern of ERalpha and ERbeta transcripts. In contrast, single striatal cells were not found to contain ERbeta despite ERalpha being present in approximately 25% of cells. The analysis of single GnRH neurons in cycling female mice revealed that the detection of ERalpha and ERbeta transcripts was lowest on proestrus (ERalpha, 18% of all GnRH neurons; ERbeta, 0%) compared with diestrus (44% and 6%) and estrus (75% and 19%, respectively). Using a novel approach that enables single cell RT-PCR analysis of GnRH neurons, we present here evidence for the cyclic expression of ERalpha and ERbeta messenger RNAs within prepubertal and adult female GnRH neurons.

Promoter transgenics reveal multiple gonadotropin-releasing hormone-I-expressing cell populations of different embryological origin in mouse brain

Gonadotropin-releasing hormone-I (GnRH-I) is thought to be expressed by a single, highly spatially restricted group of neurons, which originate in the olfactory placode and migrate through the nose into the medial septum and hypothalamus from where they control fertility. Transgenic mice bearing a 13.5 kb GnRH-I-lacZ reporter construct were derived and found to express high levels of beta-galactosidase mRNA and protein within the septohypothalamic GnRH neurons in a correct temporal and spatial manner. Unexpectedly, low levels of beta-galactosidase were also present in three further populations of cells within the lateral septum, bed nucleus of the stria terminalis, and tectum. Analysis of wild-type mice with three different GnRH-I antibodies revealed distinct and transient patterns of GnRH-I peptide expression during development in all three of these populations revealed by transgenics. The synthesis of GnRH by cells of the lateral septum was the most persistent and remained until the third postnatal week. Embryonic "small eye" Pax-6 null mice, which fail to develop an olfactory placode, were also examined and shown to have equivalent populations of GnRH-I-immunoreactive cells in the lateral septum, tectum, and bed nucleus of the stria terminalis but none of the migrating cells that form the septohypothalamic GnRH population. These results prove that so-called "ectopic" expression in promoter transgenic lines can reflect authentic developmental patterns of gene expression. They further provide the first demonstration in mammalian brain that multiple neuronal populations of different embryological origin express GnRH-I peptide during embryonic and postnatal development.

Small (SKCa) Ca2+-activated K+ channels in cultured rat hippocampal pyramidal neurones

Small (SKCa) Ca2+-activated K+ channels were identified in membrane patches excised from cultured CA1-CA3 pyramidal neurones of the neonatal rat hippocampus. When recorded in low-K+ extracellular solution ([K+]o=2.5 mM), SKCa channels had a low conductance (@3 pS at 0 mV), were activated by >/=175 nM Ca2+ (Po=0.54 at 500 nM Ca2+) and there were two open-time components (2.1 and @70 ms) to their activity. These properties of single SKCa channels are similar to those of slow after-hyperpolarization channels (sAHP) previously inferred from fluctuation analysis of the sAHP current. It is concluded that the SKCa channel reported here may be the channel that generates the sAHP in hippocampal pyramidal neurones.

Morphological and membrane properties of rat magnocellular basal forebrain neurons maintained in culture

Morphological and electrophysiological characteristics of magnocellular neurons from basal forebrain nuclei of postnatal rats (11-14 days old) were examined in dissociated cell culture. Neurons were maintained in culture for periods of 5-27 days, and 95% of magnocellular (>23 micron diam) neurons stained positive with acetylcholinesterase histochemistry. With the use of phase contrast microscopy, four morphological subtypes of magnocellular neurons could be distinguished according to the shape of their soma and pattern of dendritic branching. Corresponding passive and active membrane properties were investigated with the use of whole cell configuration of the patch-clamp technique. Neurons of all cell types displayed a prominent (6-39 mV; 6.7-50 ms duration) spike afterdepolarization (ADP), which in some cells reached firing threshold. The ADP was voltage dependent, increasing in amplitude and decreasing in duration with membrane hyperpolarization with an apparent reversal potential of -59 +/- 2.3 (SE) mV. Elevating [Ca2+]o (2.5-5.0 mM) or prolonging spike repolarization with 10 mM tetraethylammonium (TEA) or 1 mM 4-aminopyridine (4-AP), potentiated the ADP while it was inhibited by reducing [Ca2+]o (2.5-1 mM) or superfusion with Cd2+ (100 microM). The ADP was selectively inhibited by amiloride (0.1-0.3 mM or Ni2+ 10 microM) but unaffected by nifedipine (3 microM), omega-conotoxin GVIA (100 nM) or omega-agatoxin IVA (200 nM), indicating that Ca2+ entry was through T-type Ca2+ channels. After inhibition of the ADP with amiloride (300 microM), depolarization to less than -65 mV revealed a spike afterhyperpolarization (AHP) with both fast and slow components that could be inhibited by 4-AP (1 mM) and Cd2+ (100 microM), respectively. In all cell types, current-voltage relationships exhibited inward rectification at hyperpolarized potentials >/=EK (approximately -90 mV). Application of Cs+ (0.1-1 mM) or Ba2+ (1-10 microM) selectively inhibited inward rectification but had no effect on resting potential or cell excitability. At higher concentrations, Ba2+ (>10 microM) also inhibited an outward current tonically active at resting potential (VH -70 mV), which under current-clamp conditions resulted in small membrane depolarization (3-10 mV) and an increase in cell excitability. Depolarizing voltage commands from prepulse potential of -90 mV (VH -70 mV) in the presence of tetrodotoxin (0.5 microM) and Cd2+ (100 microM) to potentials between -40 and +40 mV cause voltage activation of both transient A-type and sustained delayed rectifier-type outward currents, which could be selectively inhibited by 4-AP (0.3-3 mM) and TEA (1-3 mM), respectively. These results show that, although acetylcholinesterase-positive magnocellular basal forebrain neurons exhibit considerable morphological heterogeneity, they have very similar and characteristic electrophysiological properties.

Ca2+-inhibited non-inactivating K+ channels in cultured rat hippocampal pyramidal neurones

1. Whole-cell perforated-patch recording from cultured CA1-CA3 pyramidal neurones from neonatal rat hippocampus (20-22 C; [K+]o = 2.5 mM) revealed two previously recorded non-inactivating (sustained) K+ outward currents: a voltage-independent 'leak' current (Ileak) operating at all negative potentials, and, at potentials >= -60 mV, a time- and voltage-dependent 'M-current' (IK(M)). Both were inhibited by 1 mM Ba2+ or 10 microM oxotremorine-M (Oxo-M). In ruptured-patch recording using Ca2+-free pipette solution, Ileak was strongly enhanced, and was inhibited by 1 mM Ba2+ but unaffected by 0.5 mM 4-aminopyridine (4-AP), 1 mM tetraethylammonium (TEA) or 1-10 nM margatoxin. 2. Single channels underlying these currents were sought in cell-attached patch recordings. A single class of channels of conductance approximately 7 pS showing sustained activity at resting potential and above was identified. These normally had a very low open probability (Po < 0. 1), which, however, showed a dramatic and reversible increase (to about 0.9 at approximately 0 mV) following the removal of Ca2+ from the bath. Under these (Ca2+-free) conditions, single-channel Po showed both voltage-dependent and voltage-independent components on patch depolarization from resting potential. The mean activation curve was fitted by a modified Boltzmann equation. When tested, all channels were reversibly inhibited by addition of 10 microM Oxo-M to the bath solution. 3. The channels maintained their high Po in patches excised in inside-out mode into a Ca2+-free internal solution and were strongly inhibited by application of Ca2+ to the inner face of the membrane (IC50 = 122 nM); this inhibition was observed in the absence of MgATP, and therefore was direct and unrelated to channel phosphorylation/dephosphorylation. 4. Channels in patches excised in outside-out mode were blocked by 1 mM Ba2+ but were unaffected by 4-AP or TEA. 5. Channels in cell-attached patches were inhibited after single spikes, yielding inward ensemble currents lasting several hundred milliseconds. This was prevented in Ca2+-free solution, implying that it was due to Ca2+ entry. 6. The properties of these channels (block by internal Ca2+ and external Oxo-M and Ba2+, and the presence of both voltage-dependent and voltage-independent components in their Po/V relationship) show points of resemblance to those expected for channels associated with both Ileak and IK(M) components of the sustained macroscopic currents. For this reason we designate them Ksust ('sustained current') channels. Inhibition of these channels by Ca2+ entry during an action potential may account for some forms of Ca2+-dependent after-depolarization. Their high sensitivity to internal Ca2+ may provide a new, positive feedback mechanism for cell excitation operating at low (near-resting) [Ca2+]i.

Modulation of inhibitory transmission by dopamine in rat basal forebrain nuclei: activation of presynaptic D1-like dopaminergic receptors

The effects of dopamine (DA) on inhibitory transmission onto identified magnocellular neurons were examined in rat basal forebrain slices using whole-cell recording. IPSCs evoked by focal stimulation within basal forebrain nuclei were reversibly blocked by 10 microM bicuculline and had a decay time constant of 20.1 +/- 0.77 msec in the presence of 6-cyano-7-nitroquinoxalline-2,3-dione (5 mM). Bath application of DA reduced the amplitude of IPSCs up to 71.1 +/- 1.49% in a concentration-dependent manner between 0.003 and 1 mM (the IC50 value being 6.6 microM), without any effect on the holding current at -70 mV. DA (10 microM) reduced the frequency of miniature IPSCs (mIPSCs) recorded in the presence of TTX (0.5 microM), without affecting their mean amplitude, rise time, and decay time constant. Furthermore, the DA-induced effect on mIPSCs remained unaffected by 100 microM cadmium, suggesting a presynaptic mechanism independent of calcium influx. SKF 81297, a D1-like agonist, mimicked DA-induced effect on evoked IPSCs (IC50, 10.9 microM), whereas R(-)-TNPA or (-)-quinpirole, D2-like agonists (30 microM), had little or no effect on the amplitude of evoked IPSCs. R(+)-SCH 23390, a D1-like antagonist, antagonized the DA-induced effect on IPSCs (K(B) 0.82 microM), whereas S(-)-eticlopride, a D2-like antagonist, showed slight antagonism (K(B) 7.8 microM). Forskolin (10 microM) reduced the amplitude of evoked IPSCs to approximately 58% of the control and occluded the inhibitory effect of DA. These findings indicate that DA reduces inhibitory transmission onto magnocellular basal forebrain neurons by activating presynaptic D1-like receptors.

Dopamine D1-like receptor-mediated presynaptic inhibition of excitatory transmission onto rat magnocellular basal forebrain neurones

1. Excitatory postsynaptic currents (EPSCs) following focal afferent stimulation were recorded from patch-clamped magnocellular neurones in a thin-slice preparation of the rat basal forebrain. Evoked EPSCs had a mean decay time constant of 3.81 +/- 0.09 ms and were reversibly blocked by 6-cyano-7-nitroquinoxaline-2,3-dione (CNQX, 5 microM). 2. Bath-applied dopamine (DA) reduced evoked EPSC amplitude by up to 54.2 +/- 2.3% with an IC50 of 19.9 microM in normal Krebs solution (2.5 mM Ca2+, 1.2 mM Mg2+) without effect on postsynaptic holding current. 3. DA (30 microM) reduced the mean frequency of spontaneous miniature EPSCs recorded in 0.5 microM tetrodotoxin without affecting their mean amplitude, rise time or decay time constant. This effect was diminished by 100 microM Cd2+. 4. The effect of DA on evoked EPSCs was mimicked by the D1-like receptor agonist, SKF 81297 (IC50 25.6 microM), but not by the D2-like receptor agonist R(-)-TNPA (30 microM) or (-)-quinpirole (30 microM), and was antagonized by the D1-like receptor antagonist R(+)-SCH 23390 (estimated dissociation constant KB = 1.7 microM) but not by the D2-like receptor antagonist S(-)-eticlopride (10 microM). 5. Forskolin (10 microM) reduced evoked EPSCs to approximately 60% of the control amplitude, and occluded the effect of subsequent application of DA. 6. These results suggest that glutamatergic afferents to magnocellular basal forebrain neurones possess presynaptic D1-like DA receptors, and that activation of these receptors reduces excitatory glutamatergic transmission, probably via an adenylyl cyclase-dependent pathway.

Muscarinic inhibition of glutamatergic transmissions onto rat magnocellular basal forebrain neurons in a thin-slice preparation

We have examined excitatory and inhibitory transmission in visually identified rat magnocellular basal forebrain neurons using whole-cell patch-clamp recordings in a thin-slice preparation of the rat brain. In most cells, spontaneous excitatory and inhibitory synaptic activities could be recorded from their resting membrane potential. Following focal stimulation within the basal forebrain nucleus or directly onto visualized neighbouring neurons, postsynaptic currents were elicited in magnocellular basal forebrain cells held at -70 mb (a value close to their resting membrane potential). The synaptic responses were complex, consisting either mainly of excitatory postsynaptic currents (EPSCs), or inhibitory postsynaptic currents (IPSCs), or an EPSC-IPSC sequence. The EPSC component was consistent with the activation of AMPA/KA receptors, as it could be selectively blocked by CNQX. The IPSC component resulted in the activation of GAGAA receptors, and could be blocked by bicuculline. Since GABA-mediated trasmissions were not frequently recorded, we focused on the glutamate-mediated transmission. Studies using specific calcium channel blockers suggested that both omega-conotoxin GVIA-sensitive and omega-agatoxin VIA-sensitive calcium channels contribute to the glutamatergic transmission onto magnocellular basal forebrain neurons. Carbachol (0.3-30 microM) had no observable effect on holding current, but produced a dose-dependent inhibition of the amplitude of evoked EPSCs. This cholinergic modulation was mediated by muscarinic receptors, as it could be antagonized by atropine. The inhibitory effect of carbachol on the amplitude of EPSCs could be significantly antagonized by 100 nM methoctramine, an M2-receptor antagonist. In contrast, only a small degree of antagonism could be obtained with pirenzepine, and M1-muscarinic receptor antagonist, when present at relatively high concentration of 1 microM. Moreover, the action of carbachol was presynaptic, since the frequency of miniature postsynaptic currents was reduced without affecting their amplitude. In conclusion, the present findings indicate that glutamate-mediated transmission onto magnocellular basal forebrain neurons appeared to involve both N- and P/Q-type calcium channels, and that muscarinic modulation of glutamatergic transmission to MBF neurons is mediated by a presynaptic M2-muscarinic receptor subtypes.

Single-channel activity correlated with medium-duration, Ca-dependent K current in cultured rat hippocampal neurones

Whole-cell voltage- and patch-clamp techniques were used to record the calcium-dependent component of ImAHP and correlated single-channel activity in postnatal cultured rat hippocampal neurons. The Ca-dependent ImAHP was elicited by voltage steps to + 10 mV from a holding potential of -50 mV in the whole-cell mode. In cell-attached patches, single currents of approximately 2 pA were observed following spontaneous action currents. The duration of ensemble-averaged single-channel activity was very similar to that of the whole-cell ImAHP, approximately 100 ms. Both whole-cell current and single-channel activity could be blocked by bath-applied cadmium, 200 microM. Vigorous channel activity was evoked by bursts of action potentials that are known to elicit Ca-dependent AHPs. We conclude that this channel is a candidate for mediating ImAHP.

The whole-cell calcium current in acutely dissociated magnocellular cholinergic basal forebrain neurones of the rat

1. The electrophysiological and pharmacological characteristics of the calcium current (ICa) in acutely dissociated magnocellular cholinergic basal forebrain neurones from 11- to 14-day-old post-natal rats were studied using the whole-cell patch-clamp technique. 2. All cells exhibited a small transient low-voltage-activated (LVA) current with half-activation and half-inactivation potentials of -40.2 and -49.3 mV and slope factors for activation and inactivation of 4.82 and 3.85 mV per e-fold change in membrane potential (Vm) respectively. Activation and inactivation rates for the LVA current were highly voltage dependent. For test potential changes from -50 to -20 mV, the time-to-peak of the current decreased from 39.1 to 6.4 ms, and the time constant of current decay decreased from 81.7 to 15.5 ms. 3. A high-voltage-activated (HVA) component of ICa could be elicited at threshold voltages between -46 and -30 mV from a holding potential (VH) of -80 mV. The HVA current peaked around 0 mV; a 10-fold increase in [Ca2+]o produced a 13 mV positive shift in the peak, whilst the amplitude of the current showed an approximately hyperbolic relationship to [Ca2+]o with half-saturation at 2.5 mM. The transient phase of the HVA current could be described by two exponential functions with time constants tau fast and tau slow of 16.2 and 301 ms. Steady-state inactivation of the transient and extrapolated true sustained (pedestal) components of HVA current were described by Boltzmann equations, with half-inactivation potentials (slope factors) of -47.3 mV, (9.04) and -29.2 mV (11.8) respectively. 4. omega-Conotoxin (omega-CgTX; 100 nM) irreversibly inhibited a kinetically distinct component of HVA current but had no effect upon the transient LVA current. The omega-CgTX-sensitive current could not be distinguished from the control HVA current by the voltage dependence of its activation or inactivation rates. 5. Low concentrations of amiloride (< or = 300 microM) or Ni2+ (< or = 5 microM) selectively inhibited the transient LVA current, with IC50 values of 97 and 5 microM respectively. Cd2+ (< or = 1 microM) selectively blocked a component of HVA current. At higher concentrations, Cd2+ and Ni2+ were non-selective and totally blocked all components of ICa. 6. The lanthanide ions Gd3+ and La3+ produced saturable incomplete block of the HVA current. Maximally effective concentrations of Gd3+ (100 microM) or La3+ (30 microM) inhibited 76.5 and 41.2% respectively of the sustained component of HVA current with corresponding IC50 values of 2.2 and 1.1 microM.(ABSTRACT TRUNCATED AT 400 WORDS)