The scope and severity of white-nose syndrome on hibernating bats in North America

Assessing the scope and severity of threats is necessary for evaluating impacts on populations to inform conservation planning. Quantitative threat assessment often requires monitoring programs that provide reliable data over relevant spatial and temporal scales, yet such programs can be difficult to justify until there is an apparent stressor. Leveraging efforts of wildlife management agencies to record winter counts of hibernating bats, we collated data for 5 species from over 200 sites across 27 U.S. states and 2 Canadian provinces from 1995 to 2018 to determine the impact of white-nose syndrome (WNS), a deadly disease of hibernating bats. We estimated declines of winter counts of bat colonies at sites where the invasive fungus that causes WNS (Pseudogymnoascus destructans) had been detected to assess the threat impact of WNS. Three species undergoing species status assessment by the U.S. Fish and Wildlife Service (Myotis septentrionalis, Myotis lucifugus, and Perimyotis subflavus) declined by more than 90%, which warrants classifying the severity of the WNS threat as extreme based on criteria used by NatureServe. The scope of the WNS threat as defined by NatureServe criteria was large (36% of Myotis lucifugus range) to pervasive (79% of Myotis septentrionalis range) for these species. Declines for 2 other species (Myotis sodalis and Eptesicus fuscus) were less severe but still qualified as moderate to serious based on NatureServe criteria. Data-sharing across jurisdictions provided a comprehensive evaluation of scope and severity of the threat of WNS and indicated regional differences that can inform response efforts at international, national, and state or provincial jurisdictions. We assessed the threat impact of an emerging infectious disease by uniting monitoring efforts across jurisdictional boundaries and demonstrated the importance of coordinated monitoring programs, such as the North American Bat Monitoring Program (NABat), for data-driven conservation assessments and planning.

A new approach to integrating patient-generated data with expert knowledge for personalized goal setting: A pilot study

INTRODUCTION

Self-monitoring technologies produce patient-generated data that could be leveraged to personalize nutritional goal setting to improve population health; however, most computational approaches are limited when applied to individual-level personalization with sparse and irregular self-monitoring data. We applied informatics methods from expert suggestion systems to a challenging clinical problem: generating personalized nutrition goals from patient-generated diet and blood glucose data.

MATERIALS AND METHODS

We applied qualitative process coding and decision tree modeling to understand how registered dietitians translate patient-generated data into recommendations for dietary self-management of diabetes (i.e., knowledge model). We encoded this process in a set of functions that take diet and blood glucose data as an input and output diet recommendations (i.e., inference engine). Dietitians assessed face validity. Using four patient datasets, we compared our inference engine's output to clinical narratives and gold standards developed by expert clinicians.

RESULTS

To dietitians, the knowledge model represented how recommendations from patient data are made. Inference engine recommendations were 63 % consistent with the gold standard (range = 42 %-75 %) and 74 % consistent with narrative clinical observations (range = 63 %-83 %).

DISCUSSION

Qualitative modeling and automating how dietitians reason over patient data resulted in a knowledge model representing clinical knowledge. However, our knowledge model was less consistent with gold standard than narrative clinical recommendations, raising questions about how best to evaluate approaches that integrate patient-generated data with expert knowledge.

CONCLUSION

New informatics approaches that integrate data-driven methods with expert decision making for personalized goal setting, such as the knowledge base and inference engine presented here, demonstrate the potential to extend the reach of patient-generated data by synthesizing it with clinical knowledge. However, important questions remain about the strengths and weaknesses of computer algorithms developed to discern signal from patient-generated data compared to human experts.

An investigation of the information technology needs associated with delivering chronic disease care to large clinical populations

BACKGROUND

The growing number of individuals with complex medical and social needs has motivated the adoption of care management (CM) - programs wherein multidisciplinary teams coordinate and monitor the clinical and non-clinical aspects of care for patients with chronic disease. Despite claims that health information technology (IT) is essential to CM, there has been limited research focused on the IT needs of clinicians providing care management to large groups of patients with chronic disease.

OBJECTIVE

To assess clinicians' needs pertaining to CM and to identify inefficiencies and bottlenecks associated with the delivery of CM to large groups of patients with chronic disease.

METHODS

A qualitative study of two HIV care programs. Methods included observations of multidisciplinary care team meetings and semi-structured interviews with physicians, care managers, and social workers. Thematic analysis was conducted to analyze the data.

RESULTS

CM was perceived by staff as requiring the development of novel strategies including patient prioritization and patient monitoring, which was supported by patient registries but also required the creation of additional homegrown tools. Common challenges included: limited ability to identify pertinent patient information, specifically in regards to social and behavioral determinants of health, limited assistance in matching patients to appropriate interventions, and limited support for communication within multidisciplinary care teams.

CONCLUSION

Clinicians delivering care management to chronic disease patients are not adequately supported by electronic health records and patient registries. Tools that better enable population monitoring, facilitate communication between providers, and help address psychosocial barriers to treatment could enable more effective care.

Longitudinal analysis of social and behavioral determinants of health in the EHR: exploring the impact of patient trajectories and documentation practices

Social and behavioral determinants of health (SBDH) are environmental and behavioral factors that impede disease self-management and can exacerbate clinical conditions. While recent research in the informatics community has focused on building systems that can automatically infer SBDH from the patient record, it is unclear how such determinants change overtime. This study analyzes the longitudinal characteristics of 4 common SBDH as expressed in the patient record and compares the rates of change among distinct SBDH. In addition, manual review of patient notes was undertaken to establish whether changes in patient SBDH status reflected legitimate changes in patient status or rather potential data quality issues. Our findings suggest that a patient's SBDH status is liable to change over time and that some changes reflect poor social history taking by clinicians.

Detecting Social and Behavioral Determinants of Health with Structured and Free-Text Clinical Data

BACKGROUND

Social and behavioral determinants of health (SBDH) are environmental and behavioral factors that often impede disease management and result in sexually transmitted infections. Despite their importance, SBDH are inconsistently documented in electronic health records (EHRs) and typically collected only in an unstructured format. Evidence suggests that structured data elements present in EHRs can contribute further to identify SBDH in the patient record.

OBJECTIVE

Explore the automated inference of both the presence of SBDH documentation and individual SBDH risk factors in patient records. Compare the relative ability of clinical notes and structured EHR data, such as laboratory measurements and diagnoses, to support inference.

METHODS

We attempt to infer the presence of SBDH documentation in patient records, as well as patient status of 11 SBDH, including alcohol abuse, homelessness, and sexual orientation. We compare classification performance when considering clinical notes only, structured data only, and notes and structured data together. We perform an error analysis across several SBDH risk factors.

RESULTS

Classification models inferring the presence of SBDH documentation achieved good performance (F1 score: 92.7-78.7; F1 considered as the primary evaluation metric). Performance was variable for models inferring patient SBDH risk status; results ranged from F1 = 82.7 for LGBT (lesbian, gay, bisexual, and transgender) status to F1 = 28.5 for intravenous drug use. Error analysis demonstrated that lexical diversity and documentation of historical SBDH status challenge inference of patient SBDH status. Three of five classifiers inferring topic-specific SBDH documentation and 10 of 11 patient SBDH status classifiers achieved highest performance when trained using both clinical notes and structured data.

CONCLUSION

Our findings suggest that combining clinical free-text notes and structured data provide the best approach in classifying patient SBDH status. Inferring patient SBDH status is most challenging among SBDH with low prevalence and high lexical diversity.

A visual analytics approach for pattern-recognition in patient-generated data

Objective

To develop and test a visual analytics tool to help clinicians identify systematic and clinically meaningful patterns in patient-generated data (PGD) while decreasing perceived information overload.

Methods

Participatory design was used to develop Glucolyzer, an interactive tool featuring hierarchical clustering and a heatmap visualization to help registered dietitians (RDs) identify associative patterns between blood glucose levels and per-meal macronutrient composition for individuals with type 2 diabetes (T2DM). Ten RDs participated in a within-subjects experiment to compare Glucolyzer to a static logbook format. For each representation, participants had 25 minutes to examine 1 month of diabetes self-monitoring data captured by an individual with T2DM and identify clinically meaningful patterns. We compared the quality and accuracy of the observations generated using each representation.

Results

Participants generated 50% more observations when using Glucolyzer (98) than when using the logbook format (64) without any loss in accuracy (69% accuracy vs 62%, respectively, p = .17). Participants identified more observations that included ingredients other than carbohydrates using Glucolyzer (36% vs 16%, p = .027). Fewer RDs reported feelings of information overload using Glucolyzer compared to the logbook format. Study participants displayed variable acceptance of hierarchical clustering.

Conclusions

Visual analytics have the potential to mitigate provider concerns about the volume of self-monitoring data. Glucolyzer helped dietitians identify meaningful patterns in self-monitoring data without incurring perceived information overload. Future studies should assess whether similar tools can support clinicians in personalizing behavioral interventions that improve patient outcomes.

Towards the Inference of Social and Behavioral Determinants of Sexual Health: Development of a Gold-Standard Corpus with Semi-Supervised Learning

Social and behavioral determinants of health (SBDH) are environmental and behavioral factors that are increasingly recognized for their impact on health outcomes. We describe ongoing research to extract SBDH related to sexual health from clinical documentation. Our work addresses several challenges. First, there is no standard set of SBDHs for sexual health; we describe our curation of 38 such SBDHs. Second, it is unknown how SBDH related to sexual health are expressed in clinical notes; we detail the characteristics of an annotated corpus. Third, SBDH documentations are rare; we describe the use of semi-supervised learning to accelerate the annotation process by identifying notes likely to document SBDH. Fourth, we describe preliminary results to infer an array of SBDH from clinical documentation using supervised learning.

Development and Validation of an Electronic Medical Record-Based Algorithm to Identify Patient Milestones in the Hepatitis C Virus Care Cascade

Disease-specific care cascades are important public health and organizational tools to characterize gaps in care and target resources, but they are labor-intensive to maintain. Using data available from the electronic medical record, we developed an algorithm with high accuracy for correctly representing an individual’s status in the hepatitis C virus care cascade.

Assessing the relative vulnerability of sensitive karst habitats containing rare, threatened, and endangered species in the Chesapeake and Ohio Canal National Historical Park

We were asked to provide the Chesapeake and Ohio Canal National Historical Park with information and guidance to help park managers protect and manage karst-related rare, threatened, and endangered species on park land. To do this we developed a vulnerability risk matrix based on a variety of data collected. The purpose of the matrix was to provide the park with an interactive means of evaluating the relative vulnerability of the different sites. The data collected included (1) an inventory of karst resources in the park, (2) collection of water chemistry data, and (3) an RTE assessment. Useful outcomes included a standardized scoring system for the RTE species in the park for each site, an assessment of relative risk (vulnerability of site to negative events) and impact (a measure of the damage to RTE species if a negative event would occur), and a vulnerability matrix that identifies the sites needing management or future assessment. This matrix can be easily modified and used to assess other scenarios or to accommodate the addition of new data. Other parks and sites could reproduce this type of matrix in order to manage their resources.

Using Clinical Notes and Natural Language Processing for Automated HIV Risk Assessment

OBJECTIVE

Universal HIV screening programs are costly, labor intensive, and often fail to identify high-risk individuals. Automated risk assessment methods that leverage longitudinal electronic health records (EHRs) could catalyze targeted screening programs. Although social and behavioral determinants of health are typically captured in narrative documentation, previous analyses have considered only structured EHR fields. We examined whether natural language processing (NLP) would improve predictive models of HIV diagnosis.

METHODS

One hundred eighty-one HIV+ individuals received care at New York Presbyterian Hospital before a confirmatory HIV diagnosis and 543 HIV negative controls were selected using propensity score matching and included in the study cohort. EHR data including demographics, laboratory tests, diagnosis codes, and unstructured notes before HIV diagnosis were extracted for modeling. Three predictive algorithms were developed using machine-learning algorithms: (1) a baseline model with only structured EHR data, (2) baseline plus NLP topics, and (3) baseline plus NLP clinical keywords.

RESULTS

Predictive models demonstrated a range of performance with F measures of 0.59 for the baseline model, 0.63 for the baseline + NLP topic model, and 0.74 for the baseline + NLP keyword model. The baseline + NLP keyword model yielded the highest precision by including keywords including "msm," "unprotected," "hiv," and "methamphetamine," and structured EHR data indicative of additional HIV risk factors.

CONCLUSIONS

NLP improved the predictive performance of automated HIV risk assessment by extracting terms in clinical text indicative of high-risk behavior. Future studies should explore more advanced techniques for extracting social and behavioral determinants from clinical text.

Web-based Real-Time Case Finding for the Population Health Management of Patients With Diabetes Mellitus: A Prospective Validation of the Natural Language Processing-Based Algorithm With Statewide Electronic Medical Records

Background

Diabetes case finding based on structured medical records does not fully identify diabetic patients whose medical histories related to diabetes are available in the form of free text. Manual chart reviews have been used but involve high labor costs and long latency.

Objective

This study developed and tested a Web-based diabetes case finding algorithm using both structured and unstructured electronic medical records (EMRs).

Methods

This study was based on the health information exchange (HIE) EMR database that covers almost all health facilities in the state of Maine, United States. Using narrative clinical notes, a Web-based natural language processing (NLP) case finding algorithm was retrospectively (July 1, 2012, to June 30, 2013) developed with a random subset of HIE-associated facilities, which was then blind tested with the remaining facilities. The NLP-based algorithm was subsequently integrated into the HIE database and validated prospectively (July 1, 2013, to June 30, 2014).

Results

Of the 935,891 patients in the prospective cohort, 64,168 diabetes cases were identified using diagnosis codes alone. Our NLP-based case finding algorithm prospectively found an additional 5756 uncodified cases (5756/64,168, 8.97% increase) with a positive predictive value of .90. Of the 21,720 diabetic patients identified by both methods, 6616 patients (6616/21,720, 30.46%) were identified by the NLP-based algorithm before a diabetes diagnosis was noted in the structured EMR (mean time difference = 48 days).

Conclusions

The online NLP algorithm was effective in identifying uncodified diabetes cases in real time, leading to a significant improvement in diabetes case finding. The successful integration of the NLP-based case finding algorithm into the Maine HIE database indicates a strong potential for application of this novel method to achieve a more complete ascertainment of diagnoses of diabetes mellitus.

Understanding Determinants of Racial and Ethnic Disparities in Viral Load Suppression

Racial and ethnic disparities in viral load suppression (VLS) have been well documented among people living with HIV (PLWH). The authors hypothesized that a contemporary analytic technique could reveal factors underlying these disparities and provide more explanatory power than broad stereotypes. Classification and regression tree analysis was used to detect factors associated with VLS among 11 419 adult PLWH receiving treatment from 186 New York State HIV clinics in 2013. A total of 8885 (77.8%) patients were virally suppressed. The algorithm identified 8 mutually exclusive subgroups characterized by age, housing stability, drug use, and insurance status but neither race nor ethnicity. Our findings suggest that racial and ethnic disparities in VLS exist but likely reflect underlying social and behavioral determinants of health.

The HIV Workforce in New York State: Does Patient Volume Correlate with Quality?

BACKGROUND

Knowledge of care practices among clinicians who annually treat <20 human immunodeficiency virus (HIV)-positive patients with antiretroviral therapy (ART) is insufficient, despite their number, which is likely to increase given shifting healthcare policies. We analyze the practices, distribution and quality of care provided by low-volume prescribers (LVPs) based on available data sources in New York State.

METHODS

We communicated with 1278 (66%) of the LVPs identified through a statewide claims database to determine the circumstances under which they prescribed ART in federal fiscal year 2009. We reviewed patient records from 84 LVPs who prescribed ART routinely and compared their performance with that of experienced clinicians practicing in established HIV programs.

RESULTS

Of the surveyed LVPs, 368 (29%) provided routine ambulatory care for 2323 persons living with HIV/AIDS, and 910 LVPs cited other reasons for prescribing ART. Although the majority of LVPs (73%) practiced in New York City, patients living upstate were more likely to be cared for by a LVP (odds ratio, 1.7; 95% confidence interval, 1.4-1.9). Scores for basic HIV performance measures, including viral suppression, were significantly higher in established HIV programs than for providers who wrote prescriptions for <20 persons living with HIV/AIDS (P < .01). We estimate that 33% of New York State clinicians who provide ambulatory HIV care are LVPs.

CONCLUSIONS

Our findings suggest that the quality of care associated with providers who prescribe ART for <20 patients is lower than that provided by more experienced providers. Access to experienced providers as defined by patient volume is an important determinant of delivering high-quality care and should guide HIV workforce policy decisions.

Ganglion cell loss in relation to visual disability in multiple sclerosis

PURPOSE

We used high-resolution spectral-domain optical coherence tomography (SD-OCT) with retinal segmentation to determine how ganglion cell loss relates to history of acute optic neuritis (ON), retinal nerve fiber layer (RNFL) thinning, visual function, and vision-related quality of life (QOL) in multiple sclerosis (MS).

DESIGN

Cross-sectional study.

PARTICIPANTS

A convenience sample of patients with MS (n = 122; 239 eyes) and disease-free controls (n = 31; 61 eyes). Among MS eyes, 87 had a history of ON before enrollment.

METHODS

The SD-OCT images were captured using Macular Cube (200×200 or 512×128) and ONH Cube 200×200 protocols. Retinal layer segmentation was performed using algorithms established for glaucoma studies. Thicknesses of the ganglion cell layer/inner plexiform layer (GCL+IPL), RNFL, outer plexiform/inner nuclear layers (OPL+INL), and outer nuclear/photoreceptor layers (ONL+PRL) were measured and compared in MS versus control eyes and MS ON versus non-ON eyes. The relation between changes in macular thickness and visual disability was also examined.

MAIN OUTCOME MEASURES

The OCT measurements of GCL+IPL and RNFL thickness; high contrast visual acuity (VA); low-contrast letter acuity (LCLA) at 2.5% and 1.25% contrast; on the 25-item National Eye Institute Visual Function Questionnaire (NEI-VFQ-25) and 10-Item Neuro-Ophthalmic Supplement composite score.

RESULTS

Macular RNFL and GCL+IPL were significantly decreased in MS versus control eyes (P<0.001 and P = 0.001) and in MS ON versus non-ON eyes (P<0.001 for both measures). Peripapillary RNFL, macular RNFL, GCL+IPL, and the combination of macular RNFL+GCL+IPL were significantly correlated with VA (P≤0.001), 2.5% LCLA (P<0.001), and 1.25% LCLA (P≤0.001). Among OCT measurements, reductions in GCL+IPL (P<0.001), macular RNFL (P = 0.006), and the combination (macular RNFL+GCL+IPL; P<0.001) were most strongly associated with lower (worse) NEI-VFQ-25 and 10-Item Supplement QOL scores; GCL+IPL thinning was significant even accounting for macular RNFL thickness (P = 0.03 for GCL+IPL, P = 0.39 for macular RNFL).

CONCLUSIONS

We demonstrated that GCL+IPL thinning is most significantly correlated with both visual function and vision-specific QOL in MS, and may serve as a useful structural marker of disease. Our findings parallel those of magnetic resonance imaging studies that show gray matter disease is a marker of neurologic disability in MS.

FINANCIAL DISCLOSURE(S)

Proprietary or commercial disclosure may be found after the references.

Elevated alcohol consumption in null mutant mice lacking 5-HT1B serotonin receptors

Substantial evidence links alcohol drinking and serotonin (5-HT) functioning in animals. Lowered central 5-HT neurotransmission has been found in a subgroup of alcoholics, possibly those with more aggressive, assaultive tendencies. Several rodent studies have also suggested that intact 5-HT systems are important determinants of sensitivity and/or tolerance to ethanol-induced ataxia and hypothermia. Null mutant mice lacking the 5-HT1B receptor gene (5-HT1B-/-) have been developed that display enhanced aggression and altered 5-HT release in slice preparations from some, but not all, brain areas. We characterized these mice for sensitivity to several effects of ethanol. Mutant mice drank twice as much ethanol as wild-type mice, and voluntarily ingested solutions containing up to 20% ethanol in water. Their intake of food and water, and of sucrose, saccharin and quinine solutions, was normal. Mutants were less sensitive than wild-types on a test of ethanol-induced ataxia and, with repeated drug administration, tended to develop tolerance more slowly. In tests of ethanol withdrawal and metabolism, mutants and wild-type mice showed equivalent responses. Our results suggest that the 5-HT1B receptor participates in the regulation of ethanol drinking, and demonstrate that serotonergic manipulations lead to reduced responsiveness to certain ataxic effects of ethanol without affecting dependence.

Activation of corticostriatal pathway leads to similar morphological changes observed following haloperidol treatment

Treatment with haloperidol, a dopamine receptor D-2 antagonist, for one month resulted in an increase in the mean percentage of asymmetric synapses containing a discontinuous, or perforated, postsynaptic density (PSD) [Meshul et al. (1994) Brain Res., 648:181-195] and a change in the density of striatal glutamate immunoreactivity within those presynaptic terminals [Meshul and Tan (1994) Synapse, 18:205-217]. We speculated that this haloperidol-induced change in glutamate density might be due to an activation of the corticostriatal pathway. To determine if activation of this pathway leads to similar morphological changes previously described following haloperidol treatment, GABA (10(-5) M, 0.5 microliters) was injected into the thalamic motor (VL/VM) nuclei daily for 3 weeks. This treatment resulted in an increase in the mean percentage of striatal asymmetric synapses containing a perforated PSD and an increase in the density of glutamate immunoreactivity within nerve terminals of asymmetric synapses containing a perforated or non-perforated PSD. Subchronic injections of GABA into the thalamic somatosensory nuclei (VPM/VPL) had no effect on the mean percentage of synapses with perforated PSDs but resulted in a small, but significant, increase in density of glutamate immunoreactivity. Using in vivo microdialysis, an acute injection of GABA (10(-5) M, 15 microliters) into VL/VM resulted in a prolonged rise in the extracellular level of striatal glutamate. The increase in asymmetric synapses with perforated PSDs and in glutamate immunoreactivity within nerve terminals of the striatum following either subchronic haloperidol treatment or GABA injections into VL/VM suggest that an increase in glutamate release may be a common factor in these two experiments. It is possible that the extrapyramidal side effects associated with haloperidol treatment may be due, in part, to an increase in release of glutamate within the corticostriatal pathway.

Audiogenic seizure susceptibility in WSP and WSR mice

Mice selectively bred for susceptibility (WSP, withdrawal seizure prone) and resistance (WSR, withdrawal seizure resistant) to ethanol (EtOH) withdrawal seizures were tested for susceptibility to audiogenic seizures (AGS). The seizure response of mice was studied at four ages: 17, 22, 28, and 71-78 days. WSR mice exhibited no response at any age, whereas WSP mice were sensitive on days 17, 22, and 28. The maximum number of WSP mice responding to audiogenic stimulation was observed on day 22. However, the frequency and severity of responses by WSP mice was less than that of DBA/2J mice tested under identical conditions (60 vs. 100% showing at least some response). Overall, these data suggest that susceptibility to AGS and handling-induced convulsions (HIC) during EtOH withdrawal may share some common genetic determinants and presumably some common neurochemical systems. Various treatments have been shown to enhance HIC more in WSP as compared with WSR mice. Acoustic stimulation did not induce AGS in adult mice, but the treatment significantly enhanced HIC in WSP but not WSR mice. These data strongly imply that some common neurochemical pathway may regulate susceptibility to HIC elicited by diverse treatments.

Mu-opiate receptor binding and function in HOT and COLD selected lines of mice

mu-Opiate receptor binding and function were examined in mice selectively bred for sensitivity (COLD) and resistance (HOT) to ethanol-induced hypothermia. These mice also have differential hypothermic sensitivity to mu-opiates. mu-Opiate receptor density was higher in the frontal cortex of HOT mice compared with COLD mice, but was the same in other brain areas. In addition, there were no line differences in Kd values. Basal adenylate cyclase (AC) activity was similar in both lines, as was the response to forskolin (FS) stimulation. Morphine was more effective at inhibiting FS-AC activity in the hypothalamus of HOT mice compared with COLD mice but was equally effective in the frontal and parietal cortex. There were no differences between lines in basal Ca2+, Mg2+, or Ca2+/Mg(2+)-ATPase activity. Further, 30 min after treatment ATPase activities were not altered in ethanol- or levorphanol-treated mice. These results suggests that mu-opiate biochemical pathways, but not ATPase enzyme systems, may be involved in mediating differential hypothermic sensitivity observed in HOT and COLD mice.

Olfactory bulb kindling in mice susceptible and resistant to ethanol withdrawal

The relation between kindling and susceptibility to ethanol withdrawal seizures was investigated using withdrawal seizure-prone (WSP) and withdrawal seizure-resistant (WSR) mice. These lines were developed by selective breeding to be prone and resistant, respectively, to handling-induced convulsions after chronic exposure to ethanol. Development of kindled seizures in response to electrical stimulation of the olfactory bulb was investigated in mice aged 2 and 8 months with no exposure to ethanol. Older WSP mice kindled more slowly than older WSR mice, requiring significantly more stimulations to reach the first stage 3 and the first stage 5 seizures. In younger mice, there was no significant difference between the two lines in the rate of kindling. The lower kindling rate in mature WSP mice is in contrast to their higher sensitivity to handling-induced convulsions on withdrawal from ethanol and other agents. This finding suggests that separate genetic factors underlie these two models of mouse seizures.

Antisense GAP-43 inhibits the evoked release of dopamine from PC12 cells

To investigate the role of the neuronal growth-associated protein GAP-43 (neuromodulin, B-50, F1, P-57) in neurotransmitter release, we transfected PC12 cells with a recombinant expression vector coding for antisense human GAP-43 cRNA. Two stable transfectants, designated AS1 and AS2, were selected that had integrated the recombinant sequence and expressed antisense GAP-43 RNA. Immunoblot analysis of proteins from AS1 and AS2 cells indicated that the level of GAP-43 in these cell lines was reduced. In the presence of extracellular calcium, a depolarizing concentration of K+ (56 mM) evoked dopamine release from control cells, but not from AS1 and AS2 cells. Similarly, the calcium ionophore A23187 evoked dopamine release from control cells, but was ineffective in stimulating dopamine release from AS1 and AS2 cells. The antisense transfectants, as well as the control cells, contained appreciable quantities of dopamine and secretory granules with a normal appearance. Because the expression of antisense GAP-43 RNA in PC12 cells leads to a decrease in GAP-43 expression and to the loss of evoked dopamine release, these results provide evidence of a role for GAP-43 in calcium-dependent neurotransmitter release.

Serotonin and genetic differences in sensitivity and tolerance to ethanol hypothermia

Mice have been selectively bred for genetic sensitivity (COLD) or insensitivity (HOT) to acute ethanol-induced hypothermia. COLD mice readily develop tolerance to the hypothermic effects of ethanol (EtOH) when it is chronically administered, while HOT mice do not. A number of studies have implicated serotonergic systems in both sensitivity and the development of tolerance to the hypothermic and ataxic effects of EtOH. In the experiments reported here, we administered the serotonin (5HT) neurotoxin 5,7-dihydroxytryptamine (5,7-DHT) to HOT and COLD mice before the acute and chronic administration of equipotent doses of EtOH. 5,7-DHT lesions significantly reduced (by about 65%) whole brain levels of 5HT in both selected lines. This treatment reduced sensitivity to acute EtOH hypothermia in COLD, but not in HOT mice, and blocked the development of tolerance only in COLD mice. Metabolites of 5HT, norepinephrine, and dopamine were generally increased in hypothalamic and brain stem tissue after acute EtOH injection, but HOT and COLD mice were not differentially susceptible to these effects. These results suggest that genes affecting 5HT systems may mediate some of the differences in response to the hypothermic effects of EtOH characterizing HOT and COLD mice.

Behavioral and neurochemical studies in diazepam-sensitive and -resistant mice

Benzodiazepine (BZ) effects include anxiolyis, sedation, seizure protection, and muscle relaxation; the mechanisms underlying these various effects are not understood. We have recently used the rotarod test in conjunction with selective breeding techniques to develop lines of mice which are diazepam-sensitive (DS) and diazepam-resistant (DR). We review the general methods of selective breeding, along with a description of the DS/DR selection study, and then describe a variety of behavioral and neurochemical studies which have been conducted in an attempt to characterize these mice. We have investigated the effects of other sedative drugs believed to interact with the BZ receptor, including ethanol, pentobarbital, and phenobarbital. We have also tested these mice for seizure threshold and open-field activity. DS and DR mice do not differ in diazepam-induced seizure protection, suggesting that different mechanisms underlie rotarod performance and the anti-convulsant effect. These results provide evidence to support the search for nonsedating anti-convulsants. To determine the neurochemical basis for observed differences, BZ receptor density and chloride flux have been measured. We discuss the interaction between behavioral and neurochemical approaches, and describe a conceptual framework to guide future studies with these unique new animals.

Hippocampal mossy fiber zinc deficit in mice genetically selected for ethanol withdrawal seizure susceptibility

Hippocampal mossy fiber zinc was examined in mice selectively bred for differences in susceptibility to handling-induced convulsions during ethanol withdrawal. The density of mossy fiber zinc in the CA3 stratum lucidum was significantly decreased in the duplicate lines of untreated withdrawal seizure prone (WSP) mice compared to untreated withdrawal seizure resistant (WSR) mice. Mossy fiber zinc densities in randomly bred control lines of mice (WSC) were intermediate to WSP and WSR mice. Serum, whole brain and whole hippocampal zinc were not significantly different between WSP and WSR mice, indicating that the reduction in the chelatable pool of hippocampal mossy fiber zinc was not a consequence of deficits in brain or whole body zinc nutrition. A highly significant correlation between hippocampal mossy fiber zinc density and handling-induced convulsion indices suggests that a reduction in mossy fiber zinc may be one contributing factor in the expression of seizure susceptibility in WSP mice.

Effect of neurotransmitter-selective drugs in mice selected for differential sensitivity to the hypothermic actions of ethanol

Mice selectively bred for resistance (HOT) and sensitivity (COLD) to the hypothermic effect of EtOH were tested for their hypothermic response to neurotransmitter-specific drugs and for the effect of such drugs on EtOH induced hypothermia (HT). The drugs administered were the opiate drugs morphine, levorphanol and U50488H, the dopamine agonists apomorphine, LY171535 and SKF38393, the dopamine antagonist chlorpromazine, the alpha adrenergic agonist St587, the cholinergic agonist nicotine and amphetamine, which increases the release of catecholamines. All of the drugs tested, with the exception of SKF38393 and amphetamine, induced a hypothermic response in HOT and COLD mice. SKF38393 had no effect on body temperature or HT produced by EtOH. Amphetamine caused HT at low doses and hyperthermia at high doses. COLD mice were more sensitive than HOT mice to the hypothermic effect of morphine and levorphanol, mu-opiate agonists, and U50488H, a relatively specific kappa agonist. All of the other drugs tested were approximately equally potent in HOT and COLD mice. These results suggest that the differential sensitivity of HOT and COLD mice to EtOH-induced HT may be partially mediated through genetic changes in opiate mechanisms.

Effect of alcohols and other hypnotics in mice selected for differential sensitivity to hypothermic actions of ethanol

Mice selectively bred for resistance (HOT) and sensitivity (COLD) to the hypothermic effect of an acute dose of ethanol were tested twice during the course of genetic selection for their hypothermic response to other alcohols and sedative hypnotics. The drugs administered were ethanol, propanol, n-butanol, t-butanol, pentanol, diazepam, phenobarbital, pentobarbital, methyprylon and ethchlorvynol, all of which have sedative effects on the central nervous system, and hydralazine, a peripheral vasodilator. All drugs decreased body temperature of both HOT and COLD mice. In mice selected for seven to nine generations, COLD mice were more sensitive than HOT mice to all sedative drugs. The longer-chain alcohols were more potent than ethanol in inducing hypothermia, but the magnitude of the response difference between HOT and COLD mice appeared to be smaller. The difference between HOT and COLD mice in hypothermic sensitivity to an acute dose of ethanol was greater after 11-15 generations of selection than after seven generations. Similarly, the differential effect of the other alcohols, phenobarbital, pentobarbital, and methyprylon, on HOT and COLD mice increased with more generations of selection but to a lesser extent than ethanol. These data demonstrate that selecting for sensitivity to acute ethanol hypothermia has produced mice that are also differentially sensitive to other sedative hypnotic agents. They also support the hypothesis that the drugs used in the present study share a common mechanism of action for inducing hypothermia, which may be regulated by a common set of genes.(ABSTRACT TRUNCATED AT 250 WORDS)

Genetic components of ethanol responses

A powerful technique for determining the role of a particular neurotransmitter in mediating a response to ethanol (EtOH) is the analysis of selectively bred lines of animals. Lines selected for sensitivity and resistance to an EtOH effect differ principally in gene frequencies for genes affecting the selected response. Hence, other differences between the lines are likely due to pleiotropic actions of those genes. We discuss behavioral pharmacological experiments in two sets of selected lines. Withdrawal Seizure-Prone (WSP) and -Resistant (WSR) mouse lines were selected for severe and minimal handling-induced convulsions (HIC), respectively, after withdrawal from chronic EtOH inhalation. The HIC is also elevated after acute administration of low doses of convulsant drugs. WSP mice were found to be more sensitive than WSR mice to many such drugs. There was no apparent specificity of such effects to any particular neurotransmitter system. Thus, genetic determination of a behavioral response to EtOH in this case cannot be traced to the influence of a single neurotransmitter system. COLD and HOT mice were selectively bred to show severe and mild hypothermia, respectively, after acute EtOH administration. COLD mice are also more sensitive to a number of other alcohols, barbiturates, and other general central nervous system depressants. When tested for sensitivity to a number of drugs with specific effects on neurotransmitter systems, COLD and HOT mice did not differ in sensitivity to drugs affecting dopaminergic, alpha-adrenergic, or nicotinic acetylcholinergic systems. COLD mice were more sensitive, however, to opioid and serotonergic drugs. Thus, analysis of these selected lines was successful in identifying particular neurotransmitters which may be important in EtOH-induced hypothermia.

Effect of chronic ivermectin treatment on GABA receptor function in ethanol withdrawal-seizure prone and resistant mice

Ivermectin, a potent, effective anthelmintic, is easy to administer, has a broad spectrum of action and a wide safety margin. However, no testing has been done in hosts genetically selected for seizure susceptibility which may be more sensitive to the effects of ivermectin than other animals. This was done in the present experiments with seizure prone and seizure resistant mice infested with Syphacia obvelata (pinworm). These subjects were treated daily with oral ivermectin in their drinking water every other week for six weeks, for a total of 21 days. The treatment cleared the mice of the pinworm infestation, but did not alter the seizure susceptibility or binding parameters of [3H]flunitrazepam in either of the selected lines.

Selected mouse lines, alcohol and behavior

The technique of selective breeding has been employed to develop a number of mouse lines differing in genetic sensitivity to specific effects of ethanol. Genetic animal models for sensitivity to the hypnotic, thermoregulatory, excitatory, and dependence-producing effects of alcohol have been developed. These genetic animal models have been utilized in numerous studies to assess the bases for those genetic differences, and to determine the specific neurochemical and neurophysiological bases for ethanol's actions. Work with these lines has challenged some long-held beliefs about ethanol's mechanisms of action. For example, lines genetically sensitive to one effect of ethanol are not necessarily sensitive to others, which demonstrates that no single set of genes modulates all ethanol effects. LS mice, selected for sensitivity to ethanol anesthesia, are not similarly sensitive to all anesthetic drugs, which demonstrates that all such drugs cannot have a common mechanism of action. On the other hand, WSP mice, genetically susceptible to the development of severe ethanol withdrawal, show a similar predisposition to diazepam and phenobarbital withdrawal, which suggests that there may be a common set of genes underlying drug dependencies. Studies with these models have also revealed important new directions for future mechanism-oriented research. Several studies implicate brain gamma-aminobutyric acid and dopamine systems as potentially important mediators of susceptibility to alcohol intoxication. The stability of the genetic animal models across laboratories and generations will continue to increase their power as analytic tools.

Sensitivity and tolerance to ethanol-induced hypothermia in genetically selected mice

COLD mice have been genetically selected for pronounced hypothermia (HT) after acute EtOH administration, whereas HOT mice have been selected for attenuated HT. In the current experiments, HOT and COLD mice were found to differ significantly in sensitivity to EtOH-induced HT across a range of doses: the difference was greater at higher doses. After 3 g/kg of EtOH, HOT mice displayed a 1.8 degrees C HT, whereas COLD mice had a 3.6 degrees C HT. Male mice had greater HT responses than female mice regardless of genotype. Nonselected control mice were intermediate to the HOT and COLD mice in responsiveness to EtOH. After an acute EtOH dose, HOT mice were found to have slightly lower brain EtOH concentrations than COLD mice 3 and 4 (but not 1 and 2) hr after administration of EtOH, and may have eliminated EtOH slightly more rapidly than COLD mice. When tested repeatedly in a cool ambient environment (18 degrees C), COLD mice developed tolerance to EtOH hypothermia, whereas HOT mice did not. These results confirm that sensitivity to the hypothermic effects of EtOH is influenced markedly by genotype. Furthermore, selection for neurosensitivity to EtOH has produced a correlated difference in rate or magnitude of tolerance development, which is consistent with an hypothesis of the influence of common genes determining these responses to EtOH. The difference in tolerance could not be accounted for by initial HT sensitivity differences between the lines. The HOT and COLD lines should be useful for studies of the neurobiological mechanisms of EtOH-induced HT.(ABSTRACT TRUNCATED AT 250 WORDS)

Differences in GABA activity between ethanol withdrawal seizure prone and resistant mice

Withdrawal seizure prone (WSP) and withdrawal seizure resistant (WSR) lines of mice have been genetically selected based on the severity of handling-induced convulsions after identical chronic ethanol exposure. The present experiments showed that naive WSP mice were more sensitive than WSR mice to a subconvulsant dose of picrotoxin, bicuculline or pentylenetetrazole as measured by the ability of these drugs to exacerbate handling-induced convulsions. This may reflect a difference between lines in the GABA-chloride channel. The density and affinity of [35S]t-butylbicyclophosphorothionate (TBPS) binding sites, a cage convulsant which binds to the picrotoxin site on the GABA-chloride channel, was measured in the frontal cortex, remainder of the cortex, cerebellum and hippocampus. The binding properties of [3H]flunitrazepam and the potency of gamma-aminobutyric acid (GABA) to enhance flunitrazepam binding was characterized in whole brain samples. There were no differences between lines. The behavioral results suggest a role for the GABA-chloride channel in the differential ethanol withdrawal seizure behavior of WSR and WSP mice, but this is not due to changes in receptor densities or affinities.

Functional properties of rat brain sodium channels lacking the beta 1 or beta 2 subunit

The sodium channel purified from rat brain is a heterotrimeric complex of alpha (Mr 260,000), beta 1 (Mr 36,000), and beta 2 (Mr 33,000) subunits. alpha and beta 2 are attached by disulfide bonds. Removal of beta 1 subunits by incubation in 1.0 M MgCl2 followed by reconstitution into phospholipid vesicles yielded a preparation of alpha beta 2 which did not bind [3H]saxitoxin, mediate veratridine-activated 22Na+ influx, or bind the 125I-labeled alpha-scorpion toxin from Leiurus quinquestriatus (LqTx). In contrast, removal of beta 2 subunits by reduction of disulfide bonds with 1.5 mM dithiothreitol followed by reconstitution into phospholipid vesicles yielded a preparation of alpha beta 1 that retained full sodium channel function. Alpha beta 1 bound [3H]saxitoxin with a KD of 4.1 nM at 36 degrees C. It mediated veratridine-activated 22Na+ influx at a comparable initial rate as intact sodium channels with a K0.5 for veratridine of 46 microM. Tetracaine and tetrodotoxin blocked 22Na+ influx. Like intact sodium channels, alpha beta 1 bound 125I-LqTx in a voltage-dependent manner with a KD of approximately 6 nM at a membrane potential of -60 mV and was specifically covalently labeled by azidonitrobenzoyl 125I-LqTx. When incorporated into planar phospholipid bilayers, alpha beta 1 formed batrachotoxin-activated sodium channels of 24 pS whose voltage-dependent activation was characterized by V50 = -110 mV and an apparent gating charge of 3.3 +/- 0.3. These results indicate that beta 2 subunits are not required for the function of purified and reconstituted sodium channels while a complex of alpha and beta 1 subunits is both necessary and sufficient for channel function in the purified state.

Comparison of alpha-2 adrenergic receptors and their regulation in rodent and porcine species

The alpha-2 adrenergic antagonist [3H]yohimbine (YOH) and the alpha-2 agonist [3H]p-aminoclonidine (PAC) saturably label high-affinity binding sites in the submandibular gland from 3-week-old rats and 5-week-old pigs and in the lung from neonatal rats and 5-week-old pigs. [3H]YOH had KD values of 5.5, 1.8, 0.45 and 0.22 nM in the rat gland and lung and porcine gland and lung, respectively. KD values of 2.4, 5.3 and 1.3 nM were found for [3H]PAC in rodent and pig submandibular gland and pig lung, respectively. Both 3H-ligands labeled approximately the same density of sites within each tissue except in the rat lung in which [3H]PAC binding was too low to reliably estimate. In all cases the pharmacologic profile was indicative of an alpha-2 adrenergic receptor site. However, the Ki of yohimbine vs. [3H]PAC was 30- to 140-fold higher for the rodent relative to the porcine species. GTP decreased the affinity of (-)-epinephrine and PAC at [3H]YOH-labeled sites in the pig gland and lung, but did not shift the affinity of epinephrine in the rat gland. These results suggest the possibility of subtype or species differences for the alpha-2 receptor. The Ki values of the antagonists YOH and phentolamine were different at [3H]PAC and [3H]YOH sites. GTP caused a dose-dependent reduction in [3H]PAC binding in the porcine submandibular gland and lung. At 10 microM GTP, this loss was due to a decrease in 3H-agonist affinity, but not density.(ABSTRACT TRUNCATED AT 250 WORDS)

Binding of [3H]flunitrazepam to the LM cell, a transformed murine fibroblast

LM cells have a saturable, high affinity binding site for [3H]flunitrazepam with a KD of 13 nM and a Bmax of 19 pmoles/mg protein. The IC50 values for Ro 5-4864, flunitrazepam and clonazepam against [3H]flunitrazepam were 6, 23 and 2800 nM, respectively, indicating that this receptor is of the peripheral type. A decrease of 37, 26 and 26% in Bmax was associated with substituting dimethylethanolamine, monomethylethanolamine or ethanolamine, respectively, for choline in the cell culture medium. These treatments did not change either the KD of [3H]flunitrazepam binding or the IC50 values of the different benzodiazepine drugs. Metastatic cell lines of the LM cell obtained from either athymic or C3H/Hef mice exhibited alterations in the binding parameters of [3H]flunitrazepam. There was a reduction in the Bmax values of the athymic (34%) and the C3H/Hef (44%) cell lines compared to the LM cell. In both groups there was a 90% increase in the KD. In the C6 astrocytoma, the peripheral type receptor appears to regulate plasma membrane mediated synthesis of phosphatidylcholine from phosphatidylethanolamine. However, this was not observed in the LM cell. Nor did it modulate cyclic AMP metabolism as assessed by measurement of cyclic AMP levels in whole cells after drug treatment.

Alterations in neurotransmitter receptor binding in discrete areas of the copper-deficient rat brain

Neonatal copper deficiency produced alterations in central neurotransmitter receptors that were selective with respect both to brain region and to neurotransmitter receptor type. Both high- and low-affinity dopamine receptor densities in the corpus striatum were significantly lowered, 55% and 29%, respectively, when expressed on a wet weight basis. There was a significant decrease in the level of muscarinic receptors in the striatum whether expressed on the basis of wet weight (50%) or protein (27%). A smaller reduction in muscarinic receptor density was observed in the cortex, whereas there was no effect of copper deficiency in the cerebellum. The treatment did not change beta-adrenergic receptor binding in either the cortex or cerebellum. The affinities of the receptors for the ligands was not affected by the low-copper diet. It was previously reported that copper deficiency produces regionally specific decreases in the concentrations of dopamine and norepinephrine. The greatest reduction occurred in the concentration of dopamine in the corpus striatum. The results from both studies suggest that copper deficiency in post-weanling rats may induce a selective morphological lesion.

Drug-induced surface membrane phospholipid composition in murine fibroblasts

The effects of drug on phospholipid composition of cell surface membranes are not well understood at this time. The effects of membrane-active drugs and membrane depolarization on the phospholipid composition were determined in murine LM fibroblasts. Receptor-aggregating drugs such as concanavalin A and cytoskeleton-disrupting agents such as colchicine, vinblastine, and cytochalasin B decreased phosphatidylserine content of the plasma membrane from 5.4 +/- 1.5% to as low as 1.4 +/- 0.2%. In addition, concanavalin A and colchicine increased the phosphatidylglycerol content from 6.9 +/- 1.6% to 13.1 +/- 0.7% and 10.6 +/-1.7%, respectively, while vinblastine and cytochalasin B had no effect. Pentobarbital decreased the content of phosphatidylinositol+ phosphatidylserine and of phosphatidylglycerol almost 2-fold. Propranolol, ethanol, and depolarization with 120 mM KCl had small or ne effects on plasma membrane phospholipid composition. None of the above drugs or treatments significantly altered the asymmetric distribution of phosphatidylethanolamine across the LM cell plasma membrane under the conditions tested. In addition, energy inhibitors that deplete the proton-motive force of the cell (NaN3 and KCN) and inhibitors of ATP synthesis such as NaAsO4 did not affect the asymmetric distribution of phosphatidylethanolamine. It is concluded that the mechanism of action of membrane-active drugs such as concanavalin A, vinblastine, colchicine and pentobarbital may involve alterations in plasma membrane composition. It also appears that microfilaments, microtubules, beta-adrenergic receptors, membrane fluidity, and membrane potential are not critical for the regulation of the asymmetric distribution of membrane phosphatidylethanolamine.