Single-molecule force stability of the SARS-CoV-2-ACE2 interface in variants-of-concern

Mutations in SARS-CoV-2 have shown effective evasion of population immunity and increased affinity to the cellular receptor angiotensin-converting enzyme 2 (ACE2). However, in the dynamic environment of the respiratory tract, forces act on the binding partners, which raises the question of whether not only affinity but also force stability of the SARS-CoV-2-ACE2 interaction might be a selection factor for mutations. Using magnetic tweezers, we investigate the impact of amino acid substitutions in variants of concern (Alpha, Beta, Gamma and Delta) and on force-stability and bond kinetic of the receptor-binding domain-ACE2 interface at a single-molecule resolution. We find a higher affinity for all of the variants of concern (>fivefold) compared with the wild type. In contrast, Alpha is the only variant of concern that shows higher force stability (by 17%) compared with the wild type. Using molecular dynamics simulations, we rationalize the mechanistic molecular origins of this increase in force stability. Our study emphasizes the diversity of contributions to the transmissibility of variants and establishes force stability as one of the several factors for fitness. Understanding fitness advantages opens the possibility for the prediction of probable mutations, allowing a rapid adjustment of therapeutics, vaccines and intervention measures.

Piconewton Forces Mediate GAIN Domain Dissociation of the Latrophilin-3 Adhesion GPCR

Latrophilins are adhesion G-protein coupled receptors (aGPCRs) that control excitatory synapse formation. Most aGPCRs, including latrophilins, are autoproteolytically cleaved at their GPCR-autoproteolysis inducing (GAIN) domain, but the two resulting fragments remain noncovalently associated on the cell surface. Force-mediated dissociation of the fragments is thought to activate G-protein signaling, but how this mechanosensitivity arises is poorly understood. Here, we use magnetic tweezer assays to show that physiologically relevant forces in the 1-10 pN range lead to dissociation of the latrophilin-3 GAIN domain on the seconds-to-minutes time scale, compared to days in the absence of force. In addition, we find that the GAIN domain undergoes large changes in length in response to increasing mechanical load. These data are consistent with a model in which a force-sensitive equilibrium between compact and extended GAIN domain states precedes dissociation, suggesting a mechanism by which latrophilins and other aGPCRs may mediate mechanically induced signal transduction.

Single-Molecule Manipulation in Zero-Mode Waveguides

The mechanobiology of receptor-ligand interactions and force-induced enzymatic turnover can be revealed by simultaneous measurements of force response and fluorescence. Investigations at physiologically relevant high labeled substrate concentrations require total internal reflection fluorescence microscopy or zero mode waveguides (ZMWs), which are difficult to combine with atomic force microscopy (AFM). A fully automatized workflow is established to manipulate single molecules inside ZMWs autonomously with noninvasive cantilever tip localization. A protein model system comprising a receptor-ligand pair of streptavidin blocked with a biotin-tagged ligand is introduced. The ligand is pulled out of streptavidin by an AFM cantilever leaving the receptor vacant for reoccupation by freely diffusing fluorescently labeled biotin, which can be detected in single-molecule fluorescence concurrently to study rebinding rates. This work illustrates the potential of the seamless fusion of these two powerful single-molecule techniques.

Different Vinculin Binding Sites Use the Same Mechanism to Regulate Directional Force Transduction

Vinculin is a universal adaptor protein that transiently reinforces the mechanical stability of adhesion complexes. It stabilizes mechanical connections that cells establish between the actomyosin cytoskeleton and the extracellular matrix via integrins or to neighboring cells via cadherins, yet little is known regarding its mechanical design. Vinculin binding sites (VBSs) from different nonhomologous actin-binding proteins use conserved helical motifs to associate with the vinculin head domain. We studied the mechanical stability of such complexes by pulling VBS peptides derived from talin, α-actinin, and Shigella IpaA out of the vinculin head domain. Experimental data from atomic force microscopy single-molecule force spectroscopy and steered molecular dynamics (SMD) simulations both revealed greater mechanical stability of the complex for shear-like than for zipper-like pulling configurations. This suggests that reinforcement occurs along preferential force directions, thus stabilizing those cytoskeletal filament architectures that result in shear-like pulling geometries. Large force-induced conformational changes in the vinculin head domain, as well as protein-specific fine-tuning of the VBS sequence, including sequence inversion, allow for an even more nuanced force response.

Dronpa: A Light-Switchable Fluorescent Protein for Opto-Biomechanics

Since the development of the green fluorescent protein, fluorescent proteins (FP) are indispensable tools in molecular biology. Some FPs change their structure under illumination, which affects their interaction with other biomolecules or proteins. In particular, FPs that are able to form switchable dimers became an important tool in the field of optogenetics. They are widely used for the investigation of signaling pathways, the control of surface recruitment, as well as enzyme and gene regulation. However, optogenetics did not yet develop tools for the investigation of biomechanical processes. This could be leveraged if one could find a light-switchable FP dimer that is able to withstand sufficiently high forces. In this work, we measure the rupture force of the switchable interface in pdDronpa1.2 dimers using atomic force microscopy-based single molecule force spectroscopy. The most probable dimer rupture force amounts to around 80 pN at a pulling speed of 1600 nm/s. After switching of the dimer using illumination at 488 nm, there are hardly any measurable interface interactions, which indicates the successful dissociation of the dimers. Hence this Dronpa dimer could expand the current toolbox in optogenetics with new opto-biomechanical applications like the control of tension in adhesion processes.

Monodisperse measurement of the biotin-streptavidin interaction strength in a well-defined pulling geometry

The widely used interaction of the homotetramer streptavidin with the small molecule biotin has been intensively studied by force spectroscopy and has become a model system for receptor ligand interaction. However, streptavidin's tetravalency results in diverse force propagation pathways through the different binding interfaces. This multiplicity gives rise to polydisperse force spectroscopy data. Here, we present an engineered monovalent streptavidin tetramer with a single cysteine in its functional subunit that allows for site-specific immobilization of the molecule, orthogonal to biotin binding. Functionality of streptavidin and its binding properties for biotin remain unaffected. We thus created a stable and reliable molecular anchor with a unique high-affinity binding site for biotinylated molecules or nanoparticles, which we expect to be useful for many single-molecule applications. To characterize the mechanical properties of the bond between biotin and our monovalent streptavidin, we performed force spectroscopy experiments using an atomic force microscope. We were able to conduct measurements at the single-molecule level with 1:1-stoichiometry and a well-defined geometry, in which force exclusively propagates through a single subunit of the streptavidin tetramer. For different force loading rates, we obtained narrow force distributions of the bond rupture forces ranging from 200 pN at 1,500 pN/s to 230 pN at 110,000 pN/s. The data are in very good agreement with the standard Bell-Evans model with a single potential barrier at Δx0 = 0.38 nm and a zero-force off-rate koff,0 in the 10-6 s-1 range.

Elastin-like Polypeptide Linkers for Single-Molecule Force Spectroscopy

Single-molecule force spectroscopy (SMFS) is by now well established as a standard technique in biophysics and mechanobiology. In recent years, the technique has benefitted greatly from new approaches to bioconjugation of proteins to surfaces. Indeed, optimized immobilization strategies for biomolecules and refined purification schemes are being steadily adapted and improved, which in turn has enhanced data quality. In many previously reported SMFS studies, poly(ethylene glycol) (PEG) was used to anchor molecules of interest to surfaces and/or cantilever tips. The limitation, however, is that PEG exhibits a well-known trans-trans-gauche to all-trans transition, which results in marked deviation from standard polymer elasticity models such as the worm-like chain, particularly at elevated forces. As a result, the assignment of unfolding events to protein domains based on their corresponding amino acid chain lengths is significantly obscured. Here, we provide a solution to this problem by implementing unstructured elastin-like polypeptides as linkers to replace PEG. We investigate the suitability of tailored elastin-like polypeptides linkers and perform direct comparisons to PEG, focusing on attributes that are critical for single-molecule force experiments such as linker length, monodispersity, and bioorthogonal conjugation tags. Our results demonstrate that by avoiding the ambiguous elastic response of mixed PEG/peptide systems and instead building the molecular mechanical systems with only a single bond type with uniform elastic properties, we improve data quality and facilitate data analysis and interpretation in force spectroscopy experiments. The use of all-peptide linkers allows alternative approaches for precisely defining elastic properties of proteins linked to surfaces.

Monovalent Strep-Tactin for strong and site-specific tethering in nanospectroscopy

Strep-Tactin, an engineered form of streptavidin, binds avidly to the genetically encoded peptide Strep-tag II in a manner comparable to streptavidin binding to biotin. These interactions have been used in protein purification and detection applications. However, in single-molecule studies, for example using atomic force microscopy-based single-molecule force spectroscopy (AFM-SMFS), the tetravalency of these systems impedes the measurement of monodispersed data. Here, we introduce a monovalent form of Strep-Tactin that harbours a unique binding site for Strep-tag II and a single cysteine that allows Strep-Tactin to specifically attach to the atomic force microscope cantilever and form a consistent pulling geometry to obtain homogeneous rupture data. Using AFM-SMFS, the mechanical properties of the interaction between Strep-tag II and monovalent Strep-Tactin were characterized. Rupture forces comparable to biotin:streptavidin unbinding were observed. Using titin kinase and green fluorescent protein, we show that monovalent Strep-Tactin is generally applicable to protein unfolding experiments. We expect monovalent Strep-Tactin to be a reliable anchoring tool for a range of single-molecule studies.

An evidence-based review of psychosocial treatments for bipolar disorder

Because somatotherapy for bipolar disorder (BD) has led to only modest improvements in outcome in general clinical practice, increasing attention has been paid to psychosocial interventions as adjuvants to standard medical-model treatment. This article complements and extends other recent reviews of this area by (1) evaluating psychotherapy studies according to the evidence rating criteria of the Agency for Health Care Policy and Research; (2) analyzing which outcome domains are impacted by which types of psychotherapy; (3) reviewing studies of care organization (contexts of care) for BD, tracing the roots of this area from descriptions of lithium clinics in the early 1970s through the recent federally funded controlled trials; and (4) identifying a core agenda common across most psychosocial interventions. The psychotherapy literature indicates that a broad array of modalities may be effective in improving clinical outcome, functional outcome, and disease management skills, with Class A studies supporting at least some couples/partners, cognitive-behavioral, family, and psychoeducational interventions. Controlled studies of context of care interventions are in their infancy, but are built on principles similar to those used in disease management programs for chronic medical illnesses. Despite the diversity of psychosocial interventions, there is substantial convergent validity for the importance of a common agenda of a collaborative approach to illness management that includes education about the illness, and identification of patient-specific symptom patterns, and development of action plans for response to relapse. A research agenda focusing on interventions that are sustainable in general clinical practice is of the highest priority.

Principles of effectiveness trials and their implementation in VA Cooperative Study #430: 'Reducing the efficacy-effectiveness gap in bipolar disorder'

Despite the availability of efficacious treatments for bipolar disorder, their effectiveness in general clinical practice is greatly attenuated, resulting in what has been called an 'efficacy-effectiveness gap'. In designing VA Cooperative Studies Program (CSP) Study #430 to address this gap, nine principles for conducting an effectiveness (in contrast to an efficacy) study were identified. These principles are presented and discussed, with specific aspects of CSP #430 serving as illustrations of how they can be implemented in an actual study. CSP #430 hypothesizes that an integrated, clinic-based treatment delivery system that emphasizes (1) algorithm-driven somatotherapy, (2) standardized patient education, and (3) easy access to a single primary mental health care provider to maximize continuity-of-care, will address the efficacy-effectiveness gap and improve disease, functional, and economic outcome. It is an 11-site, randomized controlled clinical trial of this multi-modal, clinic-based intervention versus usual VA care running from 1997 to 2003. The trial has enrolled 191 subjects in each arm, using minimal exclusion criteria to maximize the external validity of the study. Subjects are followed for 3 years. The intervention is highly specified in a series of operations manuals for each of the three components. Several continuous quality improvement (CQI) interventions, process measures, and statistical techniques deal with drift of care in both the intervention and usual care arms to ensure the internal validity of the study. CSP #430 is designed to have impact well beyond the VA, since it evaluates a basic health care operational principle: that augmenting ambulatory access for major mental illness will improve outcome and reduce overall treatment costs. If results are positive, this study will provide a reason to reconsider the prevailing trend toward limitation of ambulatory services that is characteristic of many managed care systems today.

The collaborative practice model for bipolar disorder: design and implementation in a multi-site randomized controlled trial

Bipolar disorder remains a high morbidity and costly illness in general clinical practice, despite the availability of efficacious medications. This 'efficacy-effectiveness gap' may be addressed by better organizing systems of care. One type of intervention is the 'collaborative practice model' which can be defined as an organization of care that a) emphasizes development in the patient of illness management skills, and b) supports provider capability and availability in order to c) engage patients in timely, joint decision-making regarding their illness. This article describes such a collaborative practice model for bipolar disorder, designed to be widely adoptable and sustainable in general clinical practice. The first part of the article describes the theoretical background from which the collaborative practice approach developed, emphasizing its origins in the lithium clinics of the 1970s, in nursing theory and practice, and more recently in the management of chronic medical diseases. The second part describes the structure of one such intervention, the Bipolar Disorders Program (BDP) developed in the Veterans Affairs health care system. The third part summarizes results from single-site studies of the intervention. The fourth part describes several key issues in its implementation in an ongoing multi-site randomized controlled trial, VA Cooperative Study Program (CSP) # 430. Data to date indicate that such collaborative practice interventions may improve important process and intermediate outcome variables for bipolar disorder. The BDP provides an example of a multi-faceted collaborative practice model that can be manualized and implemented across multiple sites in a randomized controlled trial.

Determinants of functional outcome and healthcare costs in bipolar disorder: a high-intensity follow-up study

BACKGROUND

Review of published studies reveals few data regarding determinants of the poor functional outcome and high healthcare costs that are characteristic of bipolar disorder. In order to identify potential mechanisms, critical to designing optimal treatment strategies, this longitudinal study investigated (a) the degree to which disease outcome is correlated with functional outcome and direct treatment costs, and (b) whether similar demographic or clinical characteristics predict disease and functional outcome and healthcare costs.

METHODS

Disease and functional outcome were assessed in bimonthly structured interviews over 48 weeks in 43 outpatient veterans with bipolar disorder. Direct mental health treatment costs from the VA perspective were determined from the VA database and patient interview. Regression analysis was used to determine association among the three outcome domains, and to identify clinical or demographic variables that predicted each of the three domains.

RESULTS

Functional outcome was correlated with depressive, but not manic, symptoms during follow-up. Costs were not correlated with any measure of disease or functional outcome. Several demographic, but not clinical, characteristics predicted functional outcome. In contrast, several clinical, but not demographic, characteristics predicted symptom status. No predictors were associated with direct treatment costs.

LIMITATIONS

Subjects were predominantly male veterans of relatively homogeneous social class, followed prospectively for approximately one year in a clinic designed specifically to minimize barriers to care.

CONCLUSIONS

Data from this and prior studies indicate that ongoing depressive symptoms are strongly associated with functional outcome, although substantial variance remains unexplained. Optimal models to explain functional outcome and healthcare costs will need to address factors besides simply disease severity and chronicity. The authors present a heuristic paradigm for understanding both the research and therapeutic aspects of these findings.

Self-reported quality of life across mood states in bipolar disorder

In distinction to the classic conceptualization of mania and hypomania, a growing body of work indicates that these episodes are not typically characterized by euphoric mood and sense of increased well-being, but rather by significant dysphoric symptoms. However, few data exist concerning self-perceived quality of life in mania or hypomania. Such data are important both for better understanding of the illness, and are particularly important for developing appropriate cost-utility studies. Accordingly, we hypothesized that two measures of self-reported quality of life, the mental subscale of the Short Form-12 (SF-12) and the EuroQol, would show reduced quality of life in patients in manic/hypomanic or mixed episodes, compared to those who were euthymic. Eighty-six patients with bipolar disorder from four Department of Veterans Affairs (VA) medical centers were assessed in a cross-sectional design. Mood state was categorized by physician diagnosis and separately by patient self-report using the Internal State Scale (ISS). Self-reported quality of life was quantified using the SF-12 and EuroQol. Findings were identical regardless of how mood state was determined. The SF-12 mental subscale and EuroQol differed significantly across mood states. Patients with mania/hypomania were either less than (SF-12 mental subscale) or equal to (EuroQol) euthymic patients, while patients in a mixed episode resembled those in a depressive episode on both indices. In contrast, SF-12 physical subscale scores showed no intergroup differences. These quality-of-life data provide further support for the conceptualization that mania and hypomania are syndromes characterized by reduced, rather than increased, sense of well-being and quality of life. Moreover, depressive symptoms appear to be the primary determinant of quality of life in bipolar disorder, although other factors may be associated with both depression and reduced quality of life in bipolar disorder.

The Internal State Scale: replication of its discriminating abilities in a multisite, public sector sample

OBJECTIVE

The Internal State Scale (ISS) is a self-report instrument that has been validated for discriminating mood states in patients with bipolar disorder. This study a) extends investigation to a multisite public sector sample and b) tests a revised scoring algorithm that formally identifies patients in mixed states.

METHODS

Eighty-six patients with bipolar disorder from four Veterans Affairs medical centers were assessed in a cross-sectional design. Physician-conducted semi-structured interviews used DSM-IV criteria to identify subjects as meeting criteria for euthymia, mania or hypomania, depression, or mixed state (mania or hypomania plus depression). A revised ISS scoring algorithm independently assigned mood state. Mean subscale scores were analyzed across groups. Receiver-operating characteristic (ROC) curve analysis was conducted to determine optimal algorithm structure.

RESULTS

Analysis of mean scores for the ISS subscales replicated original results for Activation, Well-Being, and Perceived Conflict, but indicated differences from the original results for the Depression Index. The ROC curve analysis identified optimal cut-off scores for the revised algorithm. The overall kappa score indicated moderate agreement between ISS and physician ratings of mood state, including mixed states.

LIMITATIONS

The study used a sample consisting primarily of male veterans. Mood state was assigned by experts using expert clinician diagnosis, not structured interviews.

CONCLUSION

The performance of the ISS in this multisite, public sector sample was similar to the performance in the initial research clinic sample. This finding confirms the validity of the ISS as a discriminator of mood states in bipolar disorder. The development of a revised scoring algorithm makes feasible formal identification of mixed episodes with the ISS.

Establishing a function-based mental health service line in a VA medical center

From 1994 through 1996, a general Veterans Affairs (VA) medical center reorganized its mental health services from a traditional discipline-based structure to a unitary service line organized around patient care functions. A comparison of data from 1993 and 1997 indicated increased efficiency, substantial transfer of patients from inpatient to outpatient care, and growth in academic programs not explainable solely by temporal, regional, or national trends or by trends within the VA medical center. Although the results should be interpreted conservatively because of the observational nature of the study, the reorganization appeared to facilitate the positive changes that occurred over the study period.

Comparison of the internal state scale to clinician-administered scales in asthma patients receiving corticosteroid therapy

Mood symptoms are reported frequently in asthma patients, particularly during corticosteroid therapy. This investigation compared the Internal State Scale (ISS), a self-report measure of symptoms of mania and depression, to the Hamilton Rating Scale for Depression (HRSD), Young Mania Rating Scale (YMRS), and Brief Psychiatric Rating Scale (BPRS) in a group of asthma patients (n=60 at baseline) before, during, and after a 1-2 week burst of prednisone. The depression and well being subscales of the ISS correlated well with HDRS scores. The perceived conflict subscale correlated with the BPRS scores. However, none of the ISS subscales correlated consistently and specifically with the YMRS in this population. Possible explanations for differences observed in bipolar versus asthma patients given the ISS are discussed. These data suggest the ISS may be a useful tool for depression symptoms and overall psychopathology in asthma patients and in patients receiving corticosteroid therapy. However, its ability may be attenuated outside of the population for which it was designed.

Sinogenic subdural empyema and Streptococcus anginosus

Subdural empyema (SDE) is most commonly caused by sinusitis and, without early diagnosis and neurosurgical intervention, is associated with high mortality. In a patient with sinusitis who presents with mental status changes, the diagnosis of SDE should be suspected on clinical grounds, even in the absence of significant computed tomographic findings. Computed tomography with contrast is a useful aid in the diagnosis of SDE, but findings may be subtle, and contrasted magnetic resonance imaging is superior. The association of Streptococcus anginosus sinusitis and related intracranial sequelae is important owing to the potentially catastrophic complications and should be recognized by otolaryngologists. In view of the rapidly progressing nature of sinogenic SDE, physicians should strongly consider early institution of aggressive therapy consisting of craniotomy with concurrent sinus drainage in patients in whom sinogenic SDE is suspected on clinical grounds, particularly in the presence of S. anginosus-positive sinus cultures.

Psychosocial interventions for bipolar disorder

The limitations of pharmacotherapy and the emergence of data supporting a role for psychosocial factors in the course of bipolar disorder have led to increased interest in the use of psychosocial interventions to improve outcomes. Although this area of study has suffered from a lack of systematic data, preliminary evidence suggests that the combined use of psychosocial interventions and medication is superior to pharmacologic treatment alone. Further research is necessary to identify and the psychosocial risk factors associated with bipolar disorder to design effective interventions to diminish their effects and improve outcome. The introduction of formal, manual-based psychotherapeutic interventions that include specific educational components has been particularly promising.

Clinical practice guidelines for bipolar disorder from the Department of Veterans Affairs

BACKGROUND

For the last several years, the Department of Veterans Affairs (VA) has been involved in the development of practice guidelines for major medical, surgical, and mental disorders. This article describes the development and content of the VA-Clinical Practice Guidelines for Bipolar Disorder, which are available in their entirety on the Journal Web site (http://www. psychiatrist.com).

METHOD

A multidisciplinary work group composed of content experts in the field of bipolar disorder and practitioners in general clinical practice was convened by the VA's Office of Performance and Quality and the Mental Health Strategic Health Group. The work group was instructed in algorithm development and methods of evidence evaluation. Draft guidelines were developed over the course of 6 months of meetings and conference calls, and that draft was then sent to nationally prominent content experts for final critique.

RESULTS

The Bipolar Guidelines are part of the family of the VA Clinical Guidelines for Management of Persons with Psychosis and consist of explicit algorithms supplemented by annotations that explain the specific decision points and their basis in the scientific literature. The guidelines are organized into 5 modules: a Core Module for diagnosis and assignment to mood state plus 4 treatment modules (Manic/Hypomanic/Mixed Episode, Bipolar Depressive Episode, Rapid Cycling, and Bipolar Disorder With Psychotic Features). The modules specify particular diagnostic and treatment tasks at each step, including both somatotherapeutic and psychotherapeutic interventions.

CONCLUSION

The VA Bipolar Guidelines are designed for easy clinical reference in decision making with individual patients, as well as for use as a scholarly reference tool. They also have utility in training activities and quality improvement programs.

Manual-based group psychotherapy for bipolar disorder: a feasibility study

BACKGROUND

The Life Goals Program is a structured, manual-based group psychotherapy program for bipolar disorder that seeks to improve patient participation in medical model treatment (phase 1) and assist patients in meeting functional status goals (phase 2). The goals of this initial study were (a) to determine whether the procedures could be exported from the authors to other therapists and (b) to quantify tolerability and impact of procedures on patients.

METHOD

Four therapists across 2 sites and 29 patients from the Veterans Affairs (VA) Medical Center were studied in an open feasibility study. Therapists were trained, and subsequent compliance with manual procedures was quantified. Several process indices measuring tolerability and impact on patients were analyzed.

RESULTS

Therapists covered 90% to 96% of phase 1 psychoeducational content, indicating excellent fidelity to manual procedures. Sixty-nine percent of patients completed phase 1, and participation scores were in the good to excellent range for 56%. Completion of phase 1 was associated with significant increase in knowledge about bipolar disorder. Fourteen (70%) of 20 patients enrolled in phase 2 reached their self-identified, behaviorally based goal (48% of the total sample who began phase 1 of the program). Mean +/- SD time to goal completion was 8.7 +/- 5.3 months (median [95% confidence interval] = 7 [5.1-12.3 months]; range, 2-17 months).

CONCLUSION

The manual-based intervention can be exported with fidelity to other therapists and sites (for phase 1). Data indicate reasonable tolerability and good achievement of process (for phases 1 and 2) for those who accept this group modality. Comparison with other manual-based psychotherapies indicates remarkable consistency regarding content for psychotherapy for bipolar disorder; major differences among the psychotherapies include mode of delivery and relative emphasis of specific components.

Adaptation of a simple patient satisfaction instrument to mental health: psychometric properties

The authors describe the psychometric properties of a simple patient satisfaction self-report instrument originally developed for use in primary care patients, adapted for use in mental health clinic patients of varied educational and socioeconomic backgrounds. The instrument demonstrated a single major principal component, high internal consistency reliability, high test-retest reliability, and sensitivity to change with experimental manipulations in clinical programming. The results also indicate that patient satisfaction is unidimensional in mental health patients as it is for primary care patients.

Predictors of service utilization in veterans with bipolar disorder: a prospective study

This study prospectively followed 103 bipolar patients enrolled in a VA treatment program for 1 year. Mental health service utilization was recorded and aggregated using the VA Cost Distribution Report. We hypothesized that previously reported predictors of disease severity would also predict service utilization, and that several other predictors of service utilization might also be identified. Analyses indicated that only the presence of a major affective episode at clinic intake and a recalled history of childhood physical abuse predicted mental health service utilization. Contrary to expectations, previously reported predictors of disease severity were not significant predictors. Implications for the study of economic outcome are discussed. In particular, we propose that economic outcome is a complex function of both patient and system factors, rather than simply being passively driven by disease severity.

[Genetic diagnosis of the hypotonic newborn]

Assessment of hypotonic newborn babies implies not only neurological studies, but; also new methods of molecular genetics, to reach a diagnosis of the aetiology. The Prader-Willi, Werdnig-Hoffmann and Myotonic Dystrophy syndromes are three conditions with neurological symptoms which have recently been defined at a molecular level.

Impact of an easy-access VA clinic-based program for patients with bipolar disorder

OBJECTIVE

The study examined the impact of easy access to ambulatory services for patients with bipolar disorder in a clinic-based program at a Veterans Affairs medical center. Core program components included medication administration based on treatment algorithms, standardized psychoeducation, and easy access to a single primary nurse provider to enhance continuity of care. The program had no community outreach or extensive rehabilitation components.

METHODS

The study used a mirror-image design to compare patients' data from the year before program entry when patients received standard clinical care with data for the first year in the program. Process and outcome data from the first 103 patients to complete one year are reported.

RESULTS

The findings indicated increased patient satisfaction and increased intensity of medication treatment without increased side effects at one year. Although scheduled ambulatory clinic visits increased as expected, use of the emergency room and the psychiatric triage team decreased significantly. Patients who were high utilizers of care before program entry experienced significant reductions in psychiatric hospital days and total mental health expenditures.

CONCLUSIONS

Easy access to ambulatory care, even if limited to clinic-based services, may have beneficial effects on important process and outcome measures for bipolar disorder. These effects may be attributable to on-demand access to services, continuity of care with a single primary provider, or improved medication delivery to reduce the "efficacy-effectiveness gap" for patients with bipolar disorder. Results indicate that augmenting, rather than limiting, access to ambulatory care for patients with major mental illnesses such as bipolar disorder may reduce overall mental health expenditures.

Evaluation of a hemostasis model for teaching basic surgical skills

The need for alternative methods of teaching veterinary medicine and surgery has increased in recent years because of increasing costs and changing public opinion. For these reasons a hemostasis model was developed that mimics the arteries and veins of the peripheral vascular system, and can be used to teach the basic skills involved in blood vessel ligation and division. This study evaluated the effectiveness of the fluid hemostasis model compared with using live animals for teaching these skills. Forty sophomore veterinary students participated in the study. Two groups of 20 students each received identical instruction in the basic techniques required for vessel ligation and division. The students then completed various exercises using inanimate models to objectively evaluate their psychomotor skills. Both groups then practiced the techniques for equal time periods; one group used the hemostasis model and the other performed a splenectomy on live dogs. After the practice session, the students were videotaped (for later evaluation), as they performed vessel ligations and divisions. The students then repeated the exercises using the inanimate models for evaluation of skills improvement. Questionnaire responses before and after the project were obtained to determine the students' views on the need for inanimate models for teaching purposes. Results of this study indicate that the hemostasis model was as effective as live animals for teaching the basic skills involved in blood vessel ligation. The students' opinions regarding the use of properly designed inanimate models for teaching these skills were dramatically changed.

Evidence of chaotic mood variation in bipolar disorder

BACKGROUND

Using long-term daily mood records obtained from patients with bipolar disorder and normal subjects, we sought to determine the temporal pattern of mood in bipolar disorder.

METHODS

Time series of 1.0 to 2.5 years from seven rapid-cycling patients with bipolar disorder and 28 normal controls were obtained. These were evaluated with several techniques to identify whether the temporal pattern of mood originates from a periodic, a random, or a deterministic source.

RESULTS

True cyclicity was not apparent in the power spectra of either the normal subjects or the patients with bipolar disorder. Instead, spectra with a broadband "l/f" shape were observed in both groups, and these spectra were significantly flatter in normal subjects (P = .02). Correlation dimension estimates are a measure of nonlinear deterministic structure, and convergent estimates could be obtained for six of the seven patients with bipolar disorder and none of the normal subjects (P < .001). Additional findings are consistent with these results.

CONCLUSIONS

These studies indicate that mood in patients with bipolar disorder is not truly cyclic for extended periods. Nonetheless, self-rated mood in bipolar disorder is significantly more organized than self-rated mood in normal subjects and can be characterized as a low-dimensional chaotic process. This characterization of the dynamics of bipolar disorder provides a unitary theoretical framework that can accommodate neurobiologic and psychosocial data and can reconcile existing models for the pathogenesis of the disorder. Furthermore, consideration of the dynamical structure of bipolar disorder may lead to new methods for predicting and controlling pathologic mood.

Testing definitions of dysphoric mania and hypomania: prevalence, clinical characteristics and inter-episode stability

37 outpatients with at least one prospectively observed manic or hypomanic episode comprised a sample for comparison of five definitions of dysphoric (hypo)mania. Dysphoric symptoms were continuously rather than bimodally distributed. Prevalence of dysphoria varied from 5 to 73% depending on the definition used. Female gender was associated with dysphoria under two of the five definitions. Inter-episode stability in patients with at least two prospectively observed episodes (n = 15) was not significantly different from chance. These data do not indicate that (hypo)mania can be dichotomized on the basis of dysphoria. Advantages and disadvantages of dimensional and categorical approaches to specifying mood in mania or hypomania are discussed.

Adverse environmental conditions in the respiratory and medical ICU settings

Sleep deprivation and fragmentation occurring in the hospital setting may have a negative impact on the respiratory system by decreasing respiratory muscle function and ventilatory response to CO2. Sleep deprivation in a patient with respiratory failure may, therefore, impair recovery and weaning from mechanical ventilation. We postulate that light, sound, and interruption levels in a weaning unit are major factors resulting in sleep disorders and possibly circadian rhythm disruption. As an initial test of this hypothesis, we sampled interruption levels and continuously monitored light and sound levels for a minimum of seven consecutive days in a medical ICU, a multiple bed respiratory care unit (RCU) room, a single-bed RCU room, and a private room. Light levels in all areas maintained a day-night rhythm, with peak levels dependent on window orientation and shading. Peak sound levels were extremely high in all areas representing values significantly higher than those recommended by the Environmental Protection Agency as acceptable for a hospital environment. The number of sound peaks greater than 80 decibels, which may result in sleep arousals, was especially high in the intensive and respiratory care areas, but did show a day-night rhythm in all settings. Patient interruptions tended to be erratic, leaving little time for condensed sleep. We conclude that the potential for environmentally induced sleep disruption is high in all areas, but especially high in the intensive and respiratory care areas where the negative consequences may be the most severe.

Palatine tonsil cyst in a dog

A 7-year-old spayed female Doberman Pinscher had a fluctuant red mass that filled the entire crypt of the left palatine tonsil. The mass was surgically excised and was found to be a tonsillar cyst on histologic examination. Because the cyst was lined with pseudostratified epithelium, embryonic origin was the most probable etiopathogenesis.

Multisite data reanalysis of the validity of rapid cycling as a course modifier for bipolar disorder in DSM-IV

OBJECTIVE

The validity of rapid cycling as a distinct course modifier for bipolar disorder was assessed by comparing patients with and without a history of rapid cycling (4 or more affective episodes in 12 months) on demographic, clinical, family history, and outcome variables. These data were also used to formulate operational criteria for the modifier.

METHOD

Data on subjects with rapid-cycling (N = 120) and nonrapid-cycling (N = 119) bipolar disorder from four sites were pooled and analyzed by using case-control and historical cohort methods.

RESULTS

The rapid-cycling group contained more women and more subjects from higher social classes than the nonrapid-cycling group. Family history did not differ between the groups. The diagnosis had predictive validity in that the rapid-cycling patients had more episodes than the nonrapid-cycling patients during prospective follow-up. The relationship between gender and episode frequency supported the validity of the cutoff point of 4-8 episodes per year. The data regarding whether patients with rapid cycling based on truncated episodes more closely resembled rapid-cycling or nonrapid-cycling patients were equivocal. Patients whose only rapid cycling was associated with antidepressants resembled spontaneously rapid-cycling patients, while the majority of spontaneously rapid-cycling patients also had periods of antidepressant-associated rapid cycling.

CONCLUSIONS

The validity of rapid cycling as a distinct course modifier for bipolar disorder is supported by differences in gender, prospectively assessed outcome, and perhaps social class between rapid-cycling and nonrapid-cycling patients. The relationship of gender to episode frequency supports the cutoff of 4 or more episodes per year.

Mood and behavioral effects of four-week light treatment in winter depressives and controls

This study investigated (1) the time-course and durability of antidepressant effects of bright light in winter depressives, and (2) the effects of bright light on mood and behavior in normal controls in a 4-week open treatment paradigm. Twelve subjects in a major depressive episode during recurrent major depressive or bipolar disorder with seasonal pattern and 12 control subjects received 2,500 lux light between 0600 and 0800 hours, while 12 controls arose at 0600 hours for quiet activities without exposure to bright light. In depressives, maximal decrements in depression ratings were not reached until the fourth week of treatment. Four depressives experienced clinically significant hypomanic symptoms. Controls treated with light demonstrated significantly higher clinician ratings of hypomanic symptoms than no-light controls. When depressives and controls were combined, seasonality, but not diagnosis, predicted the emergence of manic-like symptoms. Implications for bright light treatment in the clinical setting are discussed.

A survey of the use of live animals, cadavers, inanimate models, and computers in teaching veterinary surgery

A questionnaire, designed to gather information regarding the use of live animals, cadavers, inanimate models, and other innovative methods to teach veterinary surgery, was mailed to individuals in the surgery sections of all 31 veterinary schools in the United States and Canada. Of the 31 questionnaires mailed, 27 (87%) were completed and returned. Mean number of total, general, small-animal, and large-animal surgery laboratory sessions were 22, 5.9, 11, and 7.4, respectively. At 7 of 26 (27%) schools, animals were euthanatized prior to recovery from anesthesia in all teaching laboratories; in 18 schools (69%), small animals were euthanatized prior to recovery from anesthesia. In 4 (20%) of the 20 schools that offer large-animal laboratory courses, large animals were euthanatized prior to recovery from anesthesia. In 24 schools (88%), cadavers, models, or both were used in at least 1 laboratory session in their surgery training program. Models were used most frequently to teach suturing, knot typing, and hemostasis. Plastic bones were used in 8 (30%) schools to teach fracture repair. In several schools, models were used to teach other general psychomotor skills, and at several schools, models were available for sale to other teaching institutions. At 16 (59%) of the 27 veterinary schools, some type of program has been developed with local humane societies. At 13 (81%) of the 16 schools with such a program, small animals were euthanatized prior to recovery from anesthesia in their traditional laboratories. At 10 (37%) of the schools, some process was used to evaluate students in the laboratory, and at 5 (19%), course evaluations were completed by students taking the laboratory.(ABSTRACT TRUNCATED AT 250 WORDS)

Continuation and maintenance pharmacotherapy for unipolar and bipolar mood disorders

There is evidence that the risk for recurrence increases with each additional mood episode. Substantial data show that the probability of relapse and recurrence in both unipolar and bipolar disorders can be decreased by extended pharmacologic treatment. In recommending prolonged treatment to prevent recurrence, however, the values of each patient need to be considered, along with the age of onset, the meaning of each mood episode, its severity, and the clinical and social circumstances. Several questions remain to be answered. For instance, are there characteristics of first-episode unipolar or bipolar patients that will indicate whether extended treatment will prevent the next episode? How long should treatment be continued, and at what dose? Given the variety of treatments available for mood disorders, are there particular subsets of patients that are better suited or matched for one agent as opposed to another? What are the characteristics of bipolar patients whose depressive episodes can be treated safely with antidepressants, without risk of switching to mania? What are the costs and benefits of extended treatment, not only in terms of side effects and health service utilization, but also in terms of whether the agents we use may actually worsen the subsequent course of illness? Further questions concern the role of psychotherapy in the continuation and maintenance treatment of recurrent mood disorders. Although few clinicians would advocate psychotherapy alone for treatment of unipolar and bipolar patients at high risk for relapse and recurrence, the specific role of psychotherapy remains to be evaluated. It will be important to determine whether structured psychotherapies can provide additional benefit in terms of both episode prevention and functional outcome. This latter issue is particularly important in view of the substantial social and occupational morbidity even in remitted unipolar and bipolar patients--morbidity which is clearly significant in terms of the overall costs of mental illness. Clearly, more work needs to be done. Even the best studies indicate that a substantial proportion of patients are not helped by current treatments.

Validity of seasonal pattern as a modifier for recurrent mood disorders for DSM-IV

Data are reviewed regarding the validity of seasonal pattern (SP), according to DSM-III-R, as a modifier for recurrent mood disorders. The relationship of the DSM-III-R formulation of SP is compared with that of seasonal affective disorder (SAD) as used by the bulk of researchers in the area. Both definitions are evaluated against the criteria for validity suggested by Robins and Guze, by Kendell, and by Spitzer and Williams. While the two definitions are similar and available data support a distinct clinical syndrome of recurrent winter decrements of mood and energy, it is not yet clear whether what is identified as SP or SAD represents a distinct affective syndrome, a subtype of recurrent affective illness, or the most severe form of a widely distributed population trait. Several options for operationalized criteria sets are discussed.

Thyroid function before and after four-week light treatment in winter depressives and controls

Thyroid function in patients in a current major depressive episode during the course of recurrent major mood disorder with seasonal pattern according to DSM-IIIR was compared to that of controls before and after 4 weeks' light treatment, and to that of controls at baseline and after 4 weeks' of arising early without exposure to bright light. No consistent abnormalities in thyroxine, free thyroxine index, triiodothyronine, reverse triiodothyronine, thyrotropin, thyrotropin response to TRH infusion, or thyroid autoantibodies were seen in depressives at baseline. No differences in these parameters were seen at baseline between depressives and controls. No intergroup differences were seen with treatment, although reverse T3 decreased significantly during the protocol in all groups. These data do not support the hypothesis that the thyroid axis plays a role in the pathogenesis of winter depressive symptoms or their response to light treatment.

Irradiance responsivity and unequivocal type-1 phase responsivity of rat circadian activity rhythms

Behavioral, neuropharmacological, and molecular studies of light-induced phase shifting of rodent circadian rhythms evaluate carefully the phase dependence of light responsivity. However, much less information is available regarding the dependence of such effects on the duration and irradiance of the photic stimulus used. In this study, very brief (5-min) white light pulses of 50 microW/cm2 (175 lux) administered to hooded rats elicited unequivocal type-1 phase responsivity, without significant changes in period, and with phase shift variability comparable to that in studies using longer, higher intensity pulses. Irradiance dependence was demonstrated in the phase-delay, phase-advance, and crossover portions of the phase-response curve, with minimal phase shifting seen during the dead zone even at very high irradiance. These results indicate that maximal phase-shifting magnitude may be achieved with shorter, less intense photic stimuli than are often used in studies of the neural mechanisms involved in light responsivity of rat circadian rhythms.

Intussusception in dogs and cats: A review of 36 cases

Intussusception is recognized as a common cause of bowel obstruction in small animals. This study documents the clinical and surgical findings in nine cats and 27 dogs diagnosed as having intussusception. The main purposes of the study were to define the predisposing causes and clinical signs of intussusception and to evaluate various surgical techniques commonly employed in its treatment. No common predisposing cause could be established. Diagnosis of intussusception was based most often on clinical signs of bowel obstruction in association with the palpable abdominal mass. The majority of the intussusceptions involved the enterocolic junction. Formation of adhesions was more frequent in cats. Surgical treatments included simple reduction, manual reduction with plication, intestinal resection/anastomosis, and intestinal resection/anastamosis with plication. There was no statistically significant difference (p>0.05) in the recurrence rate of the intussusceptions when the various surgical techniques were compared. Recurrence of an intussusception was not related to either the bowel segment involved or whether a simple reduction, bowel resection, or intestinal plication was performed at the initial surgery.

Effects of hypothyroidism on rat circadian activity and temperature rhythms and their response to light

Male rats made hypothyroid by administration of propylthiouracil plus sodium ipodate in drinking water were compared to controls in terms of period of circadian activity and temperature rhythms, amount of gross motor activity, and mean temperature. Animals were studied under entrainment, constant darkness (DD), and constant dim light (LL). There was no difference in the period of the circadian activity rhythm between groups in DD. However, hypothyroid rats showed significant blunting of the period-lengthening response to increasing ambient illumination. As expected, the period of the circadian temperature rhythm increased in controls with increasing ambient illumination. In contrast, the period of the circadian temperature rhythm in hypothyroid animals actually shortened under LL compared to DD. This blunting of the period-lengthening response to increasing ambient illumination of both activity and temperature rhythms in hypothyroid animals could not be explained by differences in activity level or mean temperature between the groups.

Fractures of the mandible and maxilla

External fixation is an effective method for stabilization of many mandibular fractures. Thorough physical examination and patient stabilization should be instituted before attending to the fractures and associated soft tissue trauma. Normal occlusion rather than perfect reduction is the goal of oral fracture repair. Loose teeth or teeth in the fracture should be removed, as should any avascular bone fragments. Soft tissue wounds should be treated as for any contaminated wound. Mucosal wounds are allowed to heal by second intention. Although prophylactic perioperative antibiotics are indicated, they are usually not needed postoperatively. The three basic types of external fixators described include the Kirschner-Ehmer splint, pins or screws and acrylic, and the biphase splint. All three types are relatively easy to apply, and the principles of their application are similar. A minimum of two pins or screws are placed percutaneously in each fragment, avoiding the mandibular canal. The Kirschner-Ehmer splint is more easily adjustable than the biphase splint or the pin-acrylic splint, which use acrylic connecting bars. The advantages of fixators that use acrylic bars are that the pins or screws need not all be in the same plane and that they are more lightweight than the Kirschner-Ehmer splint. The disadvantages of the biphase splint are its increased expense and its use being limited to larger dogs. External fixators are well tolerated by the animals, and postoperative care is minimal. Mandibular fractures are usually healed in 3 to 5 weeks, and the fixators can be removed with the animal under sedation.

Independent assessment of manic and depressive symptoms by self-rating. Scale characteristics and implications for the study of mania

We report the reliability and validity of the Internal State Scale, a self-report instrument for the simultaneous assessment of severity of manic and depressive symptoms. The Internal State Scale consists of four empirically derived subscales: Activation, Well-Being, Perceived Conflict, and the Depression Index. All subscales had good internal consistency reliability. Activation subscale scores were significantly higher in manic patients than in depressed patients or control subjects, while Well-Being subscale scores were significantly lower and the Depression Index subscale scores were significantly higher in depressed patients than in the other two groups. Activation subscale scores were correlated specifically with clinician ratings of mania. Depression Index subscale scores were correlated specifically with clinician ratings of depression. Further evidence for the validity of the subscales of the Internal State Scale in reflecting manic or depressive symptoms came from discriminant function analysis in which these subscales assigned 88% of subjects to the correct diagnostic groups. In affectively ill patients who were studied in two or more mood states, Activation, Depression Index, and Well-Being subscale scores changed significantly in the predicted directions, while the same discriminant algorithm assigned 79% of mood states to the correct diagnostic category. Bimodal distribution of scores of manic patients on the Well-Being and Depression Index subscales substantiated earlier findings that euphoric mood is not an essential feature of mania. Based on findings from this and previous studies, the hypothesis is proposed that variables related to activation level, and not to mood state, constitute the core characteristics of the manic syndrome.

Measurement of tissue lithium concentration by lithium magnetic resonance spectroscopy in patients with bipolar disorder

Measurements of the lithium concentration in the occipital pole of the head and calf muscle of nine patients with bipolar disorder in remission were performed using in vivo lithium-7 nuclear magnetic resonance spectroscopy (7Li NMR). 7Li NMR measurements were performed on a 1-m-bore, 1.85-T, superconducting magnet supplemented with a multinuclear spectrometer, using 11.5-cm-diameter surface coils. The average lithium concentration in the occipital pole was 0.36 +/- 0.10 mEq/L, whereas in the muscle it was 0.50 +/- 0.17 mEq/L, both lower than the average serum lithium concentration (0.79 +/- 0.23 mEq/L). The average brain/serum lithium concentration ratio was 0.47 +/- 0.12 whereas the average muscle/serum lithium concentration ratio was 0.66 +/- 0.20. There was a positive correlation between the brain versus serum and brain versus muscle lithium concentrations. The hypothesis is advanced that the minimal effective concentration of brain lithium concentration for maintenance treatment of bipolar disorder is around 0.2-0.3 mEq/L.