Restless legs syndrome, neuroleptic-induced akathisia, and opioid-withdrawal restlessness: shared neuronal mechanisms?

Restlessness is a core symptom underlying restless legs syndrome (RLS), neuroleptic-induced akathisia, and opioid withdrawal. These three conditions also share other clinical components suggesting some overlap in their pathophysiology. Recent prospective studies demonstrate the frequent incidence of RLS-like symptoms during opioid withdrawal and supervised prescription opioid tapering. Based on the therapeutic role of µ-opioid receptor (MOR) agonists in the three clinical conditions and recent preclinical experimental data in rodents, we provide a coherent and unifying neurobiological basis for the restlessness observed in these three clinical syndromes and propose a heuristic hypothesis of a key role of the specific striatal neurons that express MORs in akathisia/restlessness.

A Harm Reduction Framework for Integrated Treatment of Co-Occurring Opioid Use Disorder and Trauma-Related Disorders

The opioid epidemic has exposed a gulf in mental health research, treatment, and policy: Most patients with comorbid trauma-related disorder (TRD) and opioid use disorder (OUD) (TRD + OUD) remain undiagnosed or unsuccessfully treated for the combination of TRD symptoms and opioid use. TRD treatments tend to be psychotherapies that are not accessible or practical for many individuals with TRD + OUD, due to TRD treatment models not systematically incorporating principles of harm reduction (HR). HR practices prioritize flexibility and unequivocally improve outcomes and save lives in the treatment of OUD. Considering the urgent need to improve TRD + OUD treatment and outcomes, we propose that the OUD and TRD fields can be meaningfully reconciled by integrating HR principles with classic phasic treatment for TRD. Adding a "prestabilization" phase of treatment for TRD - largely analogous to the precontemplation Stage of Change - creates opportunities to advance research, clinical practice, and policies and potentially improve patient outcomes.

Psychosocial challenges affecting patient-defined medication for opioid use disorder treatment outcomes in a low-income, underserved population: Application of the social-ecological framework

INTRODUCTION

Successful engagement with medication treatment for opioid use disorder is an important focus in reducing mortality associated with the opioid crisis. Mortality remains at unacceptably high levels, pointing to a need for improved understanding of factors that affect medication for opioid use disorder outcomes. This study aims to understand how barriers co-occur and interact to interfere with outcomes in methadone treatment for a low-income, underserved patient population with opioid use disorder.

METHODS

This study was conducted at a community-based drug treatment center that serves a predominately low-income, racially diverse population. Guided by the social-ecological framework, we analyzed semi-structured interviews and focus groups with patients and providers working in opioid use disorder care and recovery across Baltimore City (N = 32) to assess factors that influence methadone treatment outcomes, and how barriers co-occur and interact to worsen treatment outcomes. The study used patient-centered definitions to describe successful treatment outcomes.

RESULTS

Barriers described by both patients and providers fit into several broad levels: individual, interpersonal, institutional, community, and stigma. Participants described co-occurrence of many barriers. Further, the study identified potential interactive effects, such that interrelated barriers were seen as fueling one another and having a deleterious effect on treatment outcomes. Specifically, interrelationships between barriers were described for 1) unstable housing with social influences and mental health factors; 2) transportation with poor physical health and other competing responsibilities; 3) treatment program policies and schedule with competing responsibilities; and 4) stigma with poor physical and mental health.

CONCLUSIONS

Understanding barriers to successful medication for opioid use disorder outcomes and considering their co-occurrence may help to identify and promote interventions to mitigate their impact. This work is intended to guide future research to adapt conceptual frameworks for understanding psychosocial and structural barriers affecting opioid use disorder treatment and ultimately intervention efforts to improve treatment outcomes.

Effectiveness of Conditioned Open-label Placebo With Methadone in Treatment of Opioid Use Disorder: A Randomized Clinical Trial

Importance

Methadone treatment is the most effective evidence-based treatment for opioid use disorder (OUD), but challenges related to dosing and premature treatment dropout argue for adjunct interventions to improve outcomes. One potential behavioral intervention with low risk involves harnessing placebo effects.

Objective

To determine the effect of a pharmacologically conditioned open-label placebo (C-OLP) on 90-day methadone dose, retention, drug use, withdrawal, craving, quality of life, and sleep.

Design, Setting, and Participants

This 2-arm, open-label, single-blind randomized clinical trial was conducted between December 5, 2017, and August 2, 2019, in an academically affiliated community opioid treatment program. Analyses were conducted between October 1, 2019, and April 30, 2020. A total of 320 newly enrolled adults seeking treatment for moderate to severe OUD were assessed for study eligibility; 131 met eligibility criteria, provided informed consent, and were randomized to either C-OLP or treatment as usual (TAU) in an unequal-block (3:2) manner. Exclusion criteria were pregnancy, hospital/program transfers, and court-ordered treatment.

Interventions

Participants randomized to C-OLP received pharmacologic conditioning and a placebo pill and methadone, and participants randomized to TAU were given methadone only. Participants met with the study team 5 times: at baseline (treatment intake) and 2, 4, 8, and 12 weeks postbaseline. Interactions were balanced between the 2 groups.

Main Outcomes and Measures

Outcomes included 90-day methadone dose (primary) and treatment retention, drug use, withdrawal, craving, quality of life, and sleep quality (secondary). Analyses were conducted as intention-to-treat.

Results

Of the 131 people enrolled in the study, 54 were randomized to TAU and 77 to C-OLP. Mean (SD) age was 45.9 (11.2) years; most of the participants were Black or African American (83 [63.4%]) and male (84 [64.1%]). No significant group differences were observed in the mean (SD) 90-day methadone dose (83.1 [25.1] mg for group TAU, 79.4 [19.6] mg for group C-OLP; t = 0.621991; P = .43), but the groups differed significantly in their retention rates: 33 (61.1%) for TAU and 60 (77.9%) for C-OLP (χ21 = 4.356; P = .04; number needed to treat for the beneficial outcome of 3-month treatment retention, 6; 95% CI, 4-119). C-OLP participants also reported significantly better sleep quality.

Conclusions and Relevance

In this randomized clinical trial, C-OLP had no effect on the primary outcome of 90-day methadone dose. However, C-OLP participants were significantly more likely to remain in treatment. These findings support the use of C-OLP as a methadone treatment adjunct, but larger trials are needed to further examine the use of C-OLP.

Trial Registration

ClinicalTrials.gov Identifier: NCT02941809.

"Sometimes you have to take the person and show them how": adapting behavioral activation for peer recovery specialist-delivery to improve methadone treatment retention

BACKGROUND

Despite efficacy of medication for opioid use disorder, low-income, ethno-racial minoritized populations often experience poor opioid use disorder treatment outcomes. Peer recovery specialists, individuals with lived experience of substance use and recovery, are well-positioned to engage hard-to-reach patients in treatment for opioid use disorder. Traditionally, peer recovery specialists have focused on bridging to care rather than delivering interventions. This study builds on research in other low-resource contexts that has explored peer delivery of evidence-based interventions, such as behavioral activation, to expand access to care.

METHODS

We sought feedback on the feasibility and acceptability of a peer recovery specialist-delivered behavioral activation intervention supporting retention in methadone treatment by increasing positive reinforcement. We recruited patients and staff at a community-based methadone treatment center and peer recovery specialist working across Baltimore City, Maryland, USA. Semi-structured interviews and focus groups inquired about the feasibility and acceptability of behavioral activation, recommendations for adaptation, and acceptability of working with a peer alongside methadone treatment.

RESULTS

Participants (N = 32) shared that peer recovery specialist-delivered behavioral activation could be feasible and acceptable with adaptations. They described common challenges associated with unstructured time, for which behavioral activation could be particularly relevant. Participants provided examples of how a peer-delivered intervention could fit well in the context of methadone treatment, emphasizing the importance of flexibility and specific peer qualities.

CONCLUSIONS

Improving medication for opioid use disorder outcomes is a national priority that must be met with cost-effective, sustainable strategies to support individuals in treatment. Findings will guide adaptation of a peer recovery specialist-delivered behavioral activation intervention to improve methadone treatment retention for underserved, ethno-racial minoritized individuals living with opioid use disorder.

Harm reduction behaviors are associated with carrying naloxone among patients on methadone treatment

BACKGROUND

Despite the widespread availability of naloxone, US opioid overdose rates continue to rise. The "Cascade of Care" (CoC) is a public health approach that identifies steps in achieving specific outcomes and has been used to identify gaps in naloxone carriage among individuals with opioid use disorder (OUD). We sought to apply this framework to a treatment-seeking population with OUD that may be more inclined to engage in harm reduction behaviors.

METHODS

Patients were recruited from an urban methadone program to complete a survey. We assessed naloxone familiarity, availability, obtainability, training, and possession, as well as naloxone carriage rates, demographics, and harm reduction behaviors. A multivariable logistic regression examined associations between naloxone carriage and individual-level factors.

RESULTS

Participants (n = 97) were majority male (59%), with a mean age of 48 (SD = 12), 27% had college education or higher, 64% indicated injection drug use, and 84% reported past naloxone training. All participants endorsed familiarity with naloxone, but only 42% regularly carried naloxone. The following variables were associated with carrying naloxone: White race (aOR = 2.94, 95% CI 1.02-8.52), college education (aOR = 8.11, 95% CI 1.76-37.47), and total number of self-reported harm reduction behaviors (aOR = 1.45, 95% CI 1.00-2.11).

CONCLUSION

We found low rates of naloxone carriage among methadone-treated patients. Methadone programs provide opportunities for naloxone interventions and should target racial/ethnic minorities and individuals with lower education. The spectrum of harm reduction behaviors should be encouraged among these populations to enhance naloxone carriage.

Patient experiences of COVID-19-induced changes to methadone treatment in a large community-based opioid treatment program in Baltimore

INTRODUCTION

Following the March 2020 federal declaration of a COVID-19 public health emergency, in line with recommendations for social distancing and decreased congregation, federal agencies issued sweeping regulation changes to facilitate access to medications for opioid use disorder (MOUD) treatment. These changes allowed patients new to treatment to receive multiple days of take-home medications (THM) and to use remote technology for treatment encounters-allowances that previously had been reserved exclusively for "stable" patients who met minimum adherence and time-in-treatment criteria. The impact of these changes on low-income, minoritized patients (frequently the largest recipients of opioid treatment program [OTP]-based addiction care), however, is not well characterized. We aimed to explore the experiences of patients who were enrolled in treatment prior to COVID-19 OTP regulation changes, with the goal of understanding patients' perceptions of the impact of these changes on treatment.

METHODS

This study included semistructured, qualitative interviews with 28 patients. We used a purposeful sampling method to recruit individuals who were active in treatment just before COVID-19-related policy changes went into effect, and who were still in treatment several months later. To ensure a diverse array of perspectives, we interviewed individuals who either had or had not experienced challenges with methadone medication adherence from 3/24/21 to 6/8/21, approximately 12-15 months following the onset of COVID-19. Interviews were transcribed and coded using thematic analysis.

RESULTS

Participants were majority male (57 %), Black/African American (57 %), with a mean age of 50.1 (SD = 9.3). Fifty percent received THM prior to COVID-19, which increased to 93 % during the pandemic. COVID-19 program changes had mixed effects on treatment and recovery experiences. Themes identified convenience, safety, and employment as reasons for preferring THM. Challenges included difficulty with managing/storing medications, experiencing isolation, and concern about relapse. Furthermore, some participants reported that telebehavioral health encounters felt less personal.

CONCLUSIONS

Policymakers should consider patients' perspectives to foster a more patient-centered approach to methadone dosing that is safe, flexible, and accommodating to a diverse array of patients' needs. Additionally, technical support should be provided to OTPs to ensure interpersonal connections are maintained in the patient-provider relationship beyond the pandemic.

Race-based differences in drug use prior to onset of opioid use disorder

Rates of opioid use disorder (OUD) have increased dramatically over the past two decades, a rise that has been accompanied by changing demographics of those affected. Early exposure to drugs is a known risk factor for later development of opioid use disorder; but how and whether this risk factor may differ between racial groups is unknown. Our study seeks to identify race differences in self-report of current and past substance use in OUD-diagnosed treatment-seeking individuals. Patients (n = 157) presenting for methadone maintenance treatment at a racially diverse urban opioid treatment program were approached and consented for study involvement. Participants were administered substance use history questionnaires and urine drug screening at intake. Chi-square, t-tests, and rank-sum were used to assess race differences in demographic variables. Logistic and linear regressions assessed the relationship between race and substance use for binary and continuous variables, respectively. 61% of the population identified as Black and 39% as White. Black participants were significantly older; age was thus included as a covariate. Logistic regressions demonstrated that despite similar urine toxicology at intake, White participants were significantly more likely to report having used prescription opioids and psychedelic, stimulant, and sedative substance classes prior to their first use of non-pharmaceutical opioids. Compared to Black participants, White treatment-seeking OUD-diagnosed individuals reported using a wider range of substances ever and prior to first use of non-pharmaceutical opioids. There were no differences, however, in presentation for OUD treatment, suggesting different pathways to OUD, which may carry important clinical implications.

Peer recovery specialist-delivered, behavioral activation intervention to improve retention in methadone treatment: Results from an open-label, Type 1 hybrid effectiveness-implementation pilot trial

BACKGROUND

Despite the efficacy of methadone to treat opioid use disorder (OUD), retention is an urgent priority, particularly among low-income, minoritized populations. Peer recovery specialists are well-positioned to engage vulnerable patients, particularly when trained in an evidence-based intervention to promote retention. This hybrid effectiveness-implementation pilot trial aimed to demonstrate the proof of concept of a peer recovery specialist-delivered behavioral activation and problem solving-based approach (Peer Activate) to improve methadone retention.

METHODS

Implementation outcomes included feasibility, acceptability, and fidelity. Feasibility and acceptability were defined by the percentage of participants who initiated the intervention (≥75%) and completed ≥75% of core sessions, respectively. Fidelity was assessed via independent rating of a randomly selected 20% of sessions. The primary effectiveness outcome was methadone retention at three-months post-intervention vs. a comparison cohort initiating methadone during the same time period. Secondary outcomes included methadone adherence, substance use frequency, and substance use-related problems.

RESULTS

Benchmarks for feasibility and acceptability were surpassed: 86.5% (32/37) initiated the intervention, and 81.3% of participants who initiated attended ≥75% of core sessions. The mean independent rater fidelity score was 87.9%, indicating high peer fidelity. For effectiveness outcomes, 88.6% of participants in Peer Activate were retained in methadone treatment at three-months post-intervention-28.9% higher than individuals initiating methadone treatment alone in the same time period [χ2(1) = 10.10, p = 0.001]. Among Peer Activate participants, urine-verified methadone adherence reached 97% at post-intervention, and there was a significant reduction in substance use frequency from 48% of past two-week days used at baseline to 31.9% at post-intervention [t(25) = 1.82, p = .041]. Among participants who completed the core Peer Activate sessions (n = 26), there was a significant reduction in substance use-related problems [t(21) = 1.84, p = 0.040].

CONCLUSION

Given the rapid scale-up of peer recovery specialist programs nationwide and the urgent need to promote methadone retention, these results, although preliminary, have important potential clinical significance. The next steps are to conduct a Type 1 hybrid effectiveness-implementation randomized trial with a larger sample size and longer-term follow-up to further establish the implementation and effectiveness of the Peer Activate approach.

Practical Considerations for Treating Comorbid Posttraumatic Stress Disorder in the Addictions Clinic: Approaches to Clinical Care, Leadership, and Alleviating Shame

A practical, common-sense framework for recognizing and addressing comorbid posttraumatic stress disorder (PTSD) in the substance use disorder (SUD) clinic is outlined. The article focuses on strategies that can help establish trauma-informed care or augment an existing approach. Interventions are organized around the task of ameliorating shame (or shame sensitivity), which represents a transdiagnostic mediator of psychopathology and, potentially, capacity for change. Countershaming strategies can guide a trauma-responsive leadership approach. Considering the striking rate of underdiagnosis of PTSD among patients with SUD, implementing routine systematic PTSD screening likely represents the single most consequential trauma-informed intervention that SUD clinics can adopt.

"In their mind, they always felt less than": The role of peers in shifting stigma as a barrier to opioid use disorder treatment retention

INTRODUCTION

A substantial, national need exists for culturally acceptable, accessible opioid use disorder (OUD) treatment. Medication for opioid use disorder (MOUD) is regarded as effective in treating OUD; however, retention in MOUD programs remains low nationally. One known barrier to MOUD retention is stigma, particularly within ethno-racial minority communities. Peer recovery specialists (PRSs), individuals with shared experience in substance use and recovery, may be particularly well suited to support patients in MOUD treatment, and may have capacity to play a key role in decreasing stigma-related barriers to MOUD retention.

METHODS

This study used qualitative methods to solicit feedback on how patients receiving methadone treatment (MT) experience stigma (i.e., toward substance use [SU] and MT). Study staff also gathered information regarding how a PRS role may reduce stigma and improve retention in care, including barriers and facilitators to the PRS role shifting stigma. Study staff conducted semi-structured qualitative interviews and focus groups (N = 32) with staff and patients receiving MT at an opioid treatment program as well as PRSs in Baltimore.

RESULTS

Participants identified experiences of internalized, as well as enacted and anticipated, MT and SU stigma, and described these as barriers to treatment. Participants also identified opportunities for PRSs to shift stigma-related barriers for patients receiving MT through unique aspects of the PRS role, such as their shared lived experience.

CONCLUSIONS

Reducing stigma surrounding SUD and MT is critical for improving MOUD outcomes, and future research may consider how the PRS role can support this effort.

Functional and pharmacological role of the dopamine D4 receptor and its polymorphic variants

The functional and pharmacological significance of the dopamine D₄ receptor (D₄R) has remained the least well understood of all the dopamine receptor subtypes. Even more enigmatic has been the role of the very prevalent human DRD4 gene polymorphisms in the region that encodes the third intracellular loop of the receptor. The most common polymorphisms encode a D₄R with 4 or 7 repeats of a proline-rich sequence of 16 amino acids (D_4.4R and D_4.7R). DRD4 polymorphisms have been associated with individual differences linked to impulse control-related neuropsychiatric disorders, with the most consistent associations established between the gene encoding D_4.7R and attention-deficit hyperactivity disorder (ADHD) and substance use disorders. The function of D₄R and its polymorphic variants is being revealed by addressing the role of receptor heteromerization and the relatively avidity of norepinephrine for D₄R. We review the evidence conveying a significant and differential role of D_4.4R and D_4.7R in the dopaminergic and noradrenergic modulation of the frontal cortico-striatal pyramidal neuron, with implications for the moderation of constructs of impulsivity as personality traits. This differential role depends on their ability to confer different properties to adrenergic α_2A receptor (α_2AR)-D₄R heteromers and dopamine D₂ receptor (D₂R)-D₄R heteromers, preferentially localized in the perisomatic region of the frontal cortical pyramidal neuron and its striatal terminals, respectively. We also review the evidence to support the D₄R as a therapeutic target for ADHD and other impulse-control disorders, as well as for restless legs syndrome.

A Narrative Literature Review of the Epidemiology, Etiology, and Treatment of Co-Occurring Panic Disorder and Opioid Use Disorder

OBJECTIVE

Panic disorder is a debilitating psychiatric disorder that often co-occurs with substance use disorders. Given the current opioid epidemic, the high reported rates of comorbid panic disorder and opioid use disorder are particularly concerning. In this narrative review, we describe the literature on panic disorder and opioid use disorder co-occurrence.

METHODS

86 studies, 26 reviews, 2 commentaries, and 5 guidelines pertaining to opioid use disorder, panic disorder, and their comorbidity were identified using all EBSCO databases, PubMed, and Google Scholar.

RESULTS

First, we review epidemiological literature on the prevalence of the comorbid condition above and beyond each disorder on its own. Additionally, we discuss the challenges that complicate the differential diagnosis of panic disorder and opioid use disorder and contribute to difficulties establishing rates of comorbidity. Second, we review three theoretical models that have been proposed to explain high rates of co-occurring panic disorder and opioid use disorder: the precipitation hypothesis, the self-medication hypothesis, and the shared vulnerability hypothesis. Third, we outline how co-occurring panic and opioid use disorder may impact treatment for each condition.

CONCLUSION

Based on findings in the field, we provide recommendations for future research as well as treatment considerations for co-occurring panic and opioid use disorders.

Mobile Telemedicine for Buprenorphine Treatment in Rural Populations With Opioid Use Disorder

IMPORTANCE

The demand for medications for opioid use disorder (MOUD) in rural US counties far outweighs their availability. Novel approaches to extend treatment capacity include telemedicine (TM) and mobile treatment on demand; however, their combined use has not been reported or evaluated.

OBJECTIVE

To evaluate the use of a TM mobile treatment unit (TM-MTU) to improve access to MOUD for individuals living in an underserved rural area.

DESIGN, SETTING, AND PARTICIPANTS

This quality improvement study evaluated data collected from adult outpatients with a diagnosis of OUD enrolled in the TM-MTU initiative from February 2019 (program inception) to June 2020. Program staff traveled to rural areas in a modified recreational vehicle equipped with medical, videoconferencing, and data collection devices. Patients were virtually connected with physicians based more than 70 miles (112 km) away. Data analysis was performed from June to October 2020.

INTERVENTION

Patients received buprenorphine prescriptions after initial teleconsultation and follow-up visits from a study physician specialized in addiction psychiatry and medicine.

MAIN OUTCOMES AND MEASURES

The primary outcome was 3-month treatment retention, and the secondary outcome was opioid-positive urine screens. Exploratory outcomes included use of other drugs and patients' travel distance to treatment.

RESULTS

A total of 118 patients were enrolled in treatment, of whom 94 were seen for follow-up treatment predominantly (at least 2 of 3 visits [>50%]) on the TM-MTU; only those 94 patients' data are considered in all analyses. The mean (SD) age of patients was 36.53 (9.78) years, 59 (62.77%) were men, 71 (75.53%) identified as White, and 90 (95.74%) were of non-Hispanic ethnicity. Fifty-five patients (58.51%) were retained in treatment by 3 months (90 days) after baseline. Opioid use was reduced by 32.84% at 3 months, compared with baseline, and was negatively associated with treatment duration (F = 12.69; P = .001). In addition, compared with the nearest brick-and-mortar treatment location, TM-MTU treatment was a mean of 6.52 miles (range, 0.10-58.70 miles) (10.43 km; range, 0.16-93.92 km) and a mean of 10 minutes (range, 1-49 minutes) closer for patients.

CONCLUSIONS AND RELEVANCE

These data demonstrate the feasibility of combining TM with mobile treatment, with outcomes (retention and opioid use) similar to those obtained from office-based TM MOUD programs. By implementing a traveling virtual platform, this clinical paradigm not only helps fill the void of rural MOUD practitioners but also facilitates access to underserved populations who are less likely to reach traditional medical settings, with critical relevance in the context of the COVID-19 pandemic.

Patient Satisfaction With Medications for Opioid Use Disorder Treatment via Telemedicine: Brief Literature Review and Development of a New Assessment

Telemedicine is increasingly being used to treat patients with opioid use disorder (OUD). It has particular value in rural areas of the United States impacted by the opioid crisis as these areas have a shortage of trained addiction medicine providers. Patient satisfaction significantly impacts positive clinical outcomes in OUD treatment and thus is of great clinical interest. Yet little is known regarding patient satisfaction with the increasingly important platform of telemedicine-delivered medications for opioid use disorder (tMOUD). The goal of this review is to provide a summary of the existing literature regarding patient satisfaction with tMOUD. We also submit a novel survey based on an existing framework designed to assess tMOUD satisfaction, and present pilot data (N = 14) acquired from patients engaged in rural tMOUD care. Telemedicine provides a feasible method for delivering MOUD in rural areas, and our survey provides a useful assessment to measure patient satisfaction with tMOUD. In light of the pressing need for innovative and technology-driven solutions to the opioid epidemic (especially in light of the COVID-19 pandemic), future research should focus on the development and refinement of tools to assess the important implementation goal of patient satisfaction.

Outcomes for patients receiving telemedicine-delivered medication-based treatment for Opioid Use Disorder: A retrospective chart review

This report builds on a previous study that describes the collaboration between an urban academic medical center and a rural drug treatment center, the goal of which is to provide medication-based treatment to individuals with OUD via videoconferencing. We describe results of a retrospective chart review of 472 patients treated in the program between August 2015 and April 2019. We examined several demographic and substance use variables for individuals who consented to telemedicine treatment, retention in treatment over time, and opioid use over time to understand further the impact of prescribing buprenorphine and naltrexone via telemedicine to patients in a rural OUD treatment setting. Our findings support the effectiveness of prescribing medications via telemedicine. The inclusion of more than three times as many patients as in our prior report revealed retention rates and toxicology results that are comparable to face-to-face treatment. These findings have implications for policymakers and clinicians considering implementation of similar programs.

Buprenorphine Induction in a Rural Maryland Detention Center During COVID-19: Implementation and Preliminary Outcomes of a Novel Telemedicine Treatment Program for Incarcerated Individuals With Opioid Use Disorder

Over 10 million individuals pass through U.S. detention centers on an annual basis, with nearly two-thirds meeting criteria for drug dependence/abuse. Despite proven efficacy, treatment with medications for opioid use disorder (MOUD) is underutilized in jail settings-a gap that could be addressed using telemedicine. Here we describe a new program of telemedicine-based clinical provision of new/continuing buprenorphine treatment for individuals detained in a rural jail. Implementation objectives were completed between January and August 2020, and patient encounters were conducted between August 2020 and February 2021. We established (i) telemedicine hardware/software capability; (ii) a screening process; (iii) buprenorphine administration methods; (iv) necessary medical release procedures; (v) telemedicine encounter coordination and medication prescription procedures; and (vi) a research platform. Seven incarcerated patients have been treated, two of whom were referred from community treatment. Patients were mostly male (71%), non-Hispanic White (86%), and averaged 33 years old. All patients tested positive for an opioid upon intake and began/continued buprenorphine treatment in the jail. Average time to first MOUD appointment was 9 days and patients were maintained in treatment an average 21 days. Referrals for continuing community treatment were offered to all patients prior to discharge. We report successful implementation of telemedicine MOUD in a rural detention center, with treatment engagement and initiation occurring prior to the high-risk period of discharge. The fact that this program was launched during the height of the pandemic highlights the flexibility of telemedicine-based buprenorphine treatment. Challenges and obstacles to implementation of buprenorphine treatment in a correctional system are discussed.

Open-label dose-extending placebos for opioid use disorder: a protocol for a randomised controlled clinical trial with methadone treatment

INTRODUCTION

More than 2 million individuals in the USA have an opioid use disorder (OUD). Methadone maintenance treatment is the gold standard of medication-based treatment for OUD, but high-dose methadone is associated with cardiotoxicity and respiratory complications, among other side effects. These adverse effects make enhancing the effectiveness of lower doses of methadone an attractive therapeutic goal. Long recognised for its capacity to enhance treatment outcomes for a wide range of neuropsychiatric disorders including pain, the placebo effect offers an as-yet untested avenue to such an enhancement. This approach is particularly compelling given that individuals with substance use disorder tend to have higher salience attribution and may thereby be more sensitive to placebo effects. Our study combines two promising clinical methodologies-conditioning/dose-extension and open-label placebo-to investigate whether placebo effects can increase the effective potency of methadone in treatment-seeking OUD patients.

METHODS AND ANALYSIS

A total of 120 newly enrolled treatment-seeking OUD patients will be randomly assigned to one of two different groups: either methadone plus daily placebo dose-extension (PDE; treatment group) or methadone/treatment as usual (control). Participants will meet with study team members five times over the course of 3 months of treatment with methadone (baseline, 2 weeks, and 1, 2 and 3 months postbaseline). Throughout this study time period, methadone dosages will be adjusted by an addiction clinician blind to patient assignment, per standard clinical methods. The primary outcome is methadone dose at 3 months. Secondary outcomes include self-report of drug use; 3-month urine toxicology screen results; and treatment retention. Exploratory outcomes include several environmental as well as personality factors associated with OUD and with propensity to demonstrate a placebo effect.

ETHICS AND DISSEMINATION

Human subjects oversight for this study is provided by the University of Maryland, Baltimore and University of Maryland, College Park Institutional Review Boards. Additionally, the study protocol is reviewed annually by an independent Data and Safety Monitoring Board. Study results will be disseminated via research conference presentations and peer-reviewed publications.

TRIAL REGISTRATION NUMBER

NCT02941809.

Opioid-galanin receptor heteromers mediate the dopaminergic effects of opioids

Identifying non-addictive opioid medications is a high priority in medical sciences, but μ-opioid receptors mediate both the analgesic and addictive effects of opioids. We found a significant pharmacodynamic difference between morphine and methadone that is determined entirely by heteromerization of μ-opioid receptors with galanin Gal1 receptors, rendering a profound decrease in the potency of methadone. This was explained by methadone's weaker proficiency to activate the dopaminergic system as compared to morphine and predicted a dissociation of therapeutic versus euphoric effects of methadone, which was corroborated by a significantly lower incidence of self-report of "high" in methadone-maintained patients. These results suggest that μ-opioid-Gal1 receptor heteromers mediate the dopaminergic effects of opioids that may lead to a lower addictive liability of opioids with selective low potency for the μ-opioid-Gal1 receptor heteromer, exemplified by methadone.

Role of placebo effects in pain and neuropsychiatric disorders

The placebo (and the nocebo) effect is a powerful determinant of health outcomes in clinical disease treatment and management. Efforts to completely eradicate placebo effects have shifted dynamically, as increasingly more researchers are tuned to the potentially beneficial effects of incorporating those uncontrollable placebo effects into clinical therapeutic strategies. In this review, we highlight the major findings from placebo research, elucidating the main neurobiological systems and candidate determinants of the placebo phenomenon, and illustrate a perspective that can effectively frame future research on the topic. Finally, we issue a call for increased research on the efficacy of therapeutic strategies that incorporate placebo "tools," and argue that clinical trials of the placebo response in neuropsychiatric diseases and disorders has important and far-reaching translational and clinical relevance.

Neurodevelopmental Precursors and Consequences of Substance Use during Adolescence: Promises and Pitfalls of Longitudinal Neuroimaging Strategies

Neurocognitive and emotional regulatory deficits in substance users are often attributed to misuse; however most studies do not include a substance-naïve baseline to justify that conclusion. The etiological literature suggests that pre-existing deficits may contribute to the onset and escalation of use that are then exacerbated by subsequent use. To address this, there is burgeoning interest in conducting prospective, longitudinal neuroimaging studies to isolate neurodevelopmental precursors and consequences of adolescent substance misuse, as reflected in recent initiatives such as the NIH-led Adolescent Brain Cognitive Development (ABCD) study and the National Consortium on Alcohol and Neurodevelopment (NCANDA). To distinguish neurodevelopmental precursors from the consequences of adolescent substance use specifically, prospective, longitudinal neuroimaging studies with substance-naïve pre-adolescents are needed. The exemplar described in this article—i.e., the ongoing Adolescent Development Study (ADS)—used a targeted recruitment strategy to bolster the numbers of pre-adolescent individuals who were at increased risk of substance use (i.e., “high-risk”) in a sample that was relatively small for longitudinal studies of similar phenomena, but historically large for neuroimaging (i.e., N = 135; 11–13 years of age). At baseline participants underwent MRI testing and a large complement of cognitive and behavioral assessments along with genetics, stress physiology and interviews. The study methods include repeating these measures at three time points (i.e., baseline/Wave 1, Wave 2 and Wave 3), 18 months apart. In this article, rather than outlining specific study outcomes, we describe the breadth of the numerous complexities and challenges involved in conducting this type of prospective, longitudinal neuroimaging study and “lessons learned” for subsequent efforts are discussed. While these types of large longitudinal neuroimaging studies present a number of logistical and scientific challenges, the wealth of information obtained about the precursors and consequences of adolescent substance use provides unique insights into the neurobiological bases for adolescent substance use that will lay the groundwork for targeted interventions.

Functional Connectivity Hubs and Networks in the Awake Marmoset Brain

In combination with advances in analytical methods, resting-state fMRI is allowing unprecedented access to a better understanding of the network organization of the brain. Increasing evidence suggests that this architecture may incorporate highly functionally connected nodes, or “hubs”, and we have recently proposed local functional connectivity density (lFCD) mapping to identify highly-connected nodes in the human brain. Here, we imaged awake nonhuman primates to test whether, like the human brain, the marmoset brain contains FC hubs. Ten adult common marmosets (Callithrix jacchus) were acclimated to mild, comfortable restraint using individualized helmets. Following restraint training, resting BOLD data were acquired during eight consecutive 10 min scans for each subject. lFCD revealed prominent cortical and subcortical hubs of connectivity across the marmoset brain; specifically, in primary and secondary visual cortices (V1/V2), higher-order visual association areas (A19M/V6[DM]), posterior parietal and posterior cingulate areas (PGM and A23b/A31), thalamus, dorsal and ventral striatal areas (caudate, putamen, lateral septal nucleus, and anterior cingulate cortex (A24a). lFCD hubs were highly connected to widespread areas of the brain, and further revealed significant network-network interactions. These data provide a baseline platform for future investigations in a nonhuman primate model of the brain’s network topology.

Delayed emergence of methamphetamine's enhanced cardiovascular effects in nonhuman primates during protracted methamphetamine abstinence

BACKGROUND

Methamphetamine abuse is linked with brain abnormalities, but its peripheral effects constitute an integral aspect of long-term methamphetamine use.

METHODS

Eight male rhesus monkeys with long histories of intravenous methamphetamine self-administration were evaluated 1 day, and 1, 4, 12, 26, and 52 weeks after their last methamphetamine self-administration session. On test days, isoflurane-anesthetized animals received a 0.35 mg/kg IV methamphetamine challenge. A control group consisted of 10 age and gender matched drug naïve monkeys. Cardiovascular responses to methamphetamine were followed for 2.5h. Echocardiograms were acquired at 3 and 12 months of abstinence and in the control animals.

RESULTS

No pre-methamphetamine baseline differences existed among 7 physiological measures across all conditions and controls. As expected, methamphetamine increased heart rate and blood pressure in controls. However, immediately following the self-administration period, the blood pressure response to methamphetamine challenge was reduced when compared to control monkeys. The peak and 150-min average heart rate increases, as well as peak blood pressure increases following methamphetamine were significantly elevated between weeks 12 to 26 of abstinence. These data indicate the development of tolerance followed by sensitization to methamphetamine cardiovascular effects. Echocardiography demonstrated decreased left ventricular ejection fraction and cardiac output at 3 months of abstinence. Importantly, both cardiovascular sensitization and cardiotoxicity appeared to be reversible as they returned toward control group levels after 1 year of abstinence.

CONCLUSIONS

Enhanced cardiovascular effects may occur after prolonged abstinence in addicts relapsing to methamphetamine and may underlie clinically reported acute cardiotoxic events.

Withdrawal from long-term methamphetamine self-administration 'normalizes' neurometabolites in rhesus monkeys: a (1) H MR spectroscopy study

(1) H magnetic resonance spectroscopy has demonstrated alterations in several neurometabolites in methamphetamine (METH)-dependent individuals in brain regions implicated in addiction. Yet, it is unclear whether these neurochemicals return to homeostatic levels after an individual abstains from drug use, a difficult question to address due to high recidivism and poor study retention in human subjects. We thus utilized a non-human primate model of addiction to explore the effects of long-term drug exposure and withdrawal on brain neurochemistry. Ten rhesus macaque monkeys on an active METH self-administration protocol (average use 4.6 ± 0.8 years, average daily intake between 0.4 and 1.2 mg/kg) and 10 age- and sex-matched drug-naive controls (CONT) served as subjects. Concentrations of several neurochemicals were evaluated at several timepoints following withdrawal from drug availability (10 monkeys at 1 week and 1 and 3 months, and 6 monkeys at 6 and 12 months; CONT examined at one timepoint). At 1 week following METH withdrawal, we found increases in myo-inositol in anterior cingulate cortex in the METH group relative to CONT. These alterations showed a linear pattern of decreased levels ('normalization') by 1 year of abstinence. We also found decreases in glutamine and Glx (composed mainly of glutamate and glutamine) in the caudate-putamen of the same animals at early withdrawal that showed a similar linear pattern of increasing concentration by 1 year. These results demonstrate that despite protracted, long-term use, neurochemical changes seen following long-term drug administration do not persist following prolonged abstinence, suggesting therapeutic effects of long-term withdrawal from drug use.

Personality traits and vulnerability or resilience to substance use disorders

Clear evidence supports a genetic basis for substance use disorders (SUD). Yet, the search to identify individual gene contributions to SUD has been unsuccessful. Here, we argue for the study of endophenotypes within the frame of individual differences, and identify three high-order personality traits that are tied to specific brain systems and genes, and that offer a tractable approach to studying SUD. These personality traits, and the genes that moderate them, interact dynamically with the environment and with the drugs themselves to determine ultimately an individual's vulnerability or resilience to developing SUD.

Rodent models of adaptive decision making

Adaptive decision making affords the animal the ability to respond quickly to changes in a dynamic environment: one in which attentional demands, cost or effort to procure the reward, and reward contingencies change frequently. The more flexible the organism is in adapting choice behavior, the more command and success the organism has in navigating its environment. Maladaptive decision making is at the heart of much neuropsychiatric disease, including addiction. Thus, a better understanding of the mechanisms that underlie normal, adaptive decision making helps achieve a better understanding of certain diseases that incorporate maladaptive decision making as a core feature. This chapter presents three general domains of methods that the experimenter can manipulate in animal decision-making tasks: attention, effort, and reward contingency. Here, we present detailed methods of rodent tasks frequently employed within these domains: the Attentional Set-Shift Task, Effortful T-maze Task, and Visual Discrimination Reversal Learning. These tasks all recruit regions within the frontal cortex and the striatum, and performance is heavily modulated by the neurotransmitter dopamine, making these assays highly valid measures in the study of psychostimulant addiction.

Reversal-specific learning impairments after a binge regimen of methamphetamine in rats: possible involvement of striatal dopamine

A growing body of evidence indicates that protracted use of methamphetamine (mAMPH) causes long-term impairments in cognitive function in humans. Aside from the widely reported problems with attention, mAMPH users exhibit learning and memory deficits, particularly on tasks requiring response control. Although binge mAMPH administration to animals results in cognitive deficits, few studies have attempted to test behavioral flexibility in animals after mAMPH exposure. The aim of this study was to evaluate whether mAMPH would produce impairments in two tasks assessing flexible responding in rats: a touchscreen-based discrimination-reversal learning task and an attentional set shift task (ASST) based on a hallmark test of executive function in humans, the Wisconsin Card Sort. We treated male Long-Evans rats with a regimen of four injections of 2 mg/kg mAMPH (or vehicle) within a single day, a dosing regimen shown earlier to produce object recognition impairments. We then tested them on (1) reversal learning after pretreatment discrimination learning or (2) the ASST. Early reversal learning accuracy was impaired in mAMPH-treated rats. MAMPH pretreatment also selectively impaired reversal performance during ASST testing, leaving set-shifting performance intact. Postmortem analysis of [(125)I]RTI-55 binding revealed small (10-20%) but significant reductions in striatal dopamine transporters produced by this mAMPH regimen. Together, these results lend new information to the growing field documenting impaired cognition after mAMPH exposure, and constitute a rat model of the widely reported decision-making deficits resulting from mAMPH abuse seen in humans.

Use of self-actuating and self-sensing cantilevers for imaging biological samples in fluid

In this paper, we present a detailed investigation into the suitability of atomic force microscopy (AFM) cantilevers with integrated deflection sensor and micro-actuator for imaging of soft biological samples in fluid. The Si cantilevers are actuated using a micro-heater at the bottom end of the cantilever. Sensing is achieved through p-doped resistors connected in a Wheatstone bridge. We investigated the influence of the water on the cantilever dynamics, the actuation and the sensing mechanisms, as well as the crosstalk between sensing and actuation. Successful imaging of yeast cells in water using the integrated sensor and actuator shows the potential of the combination of this actuation and sensing method. This constitutes a major step towards the automation and miniaturization required to establish AFM in routine biomedical diagnostics and in vivo applications.

Long-term changes in dopamine-stimulated gene expression after single-day methamphetamine exposure

Methamphetamine (mAMPH) is a highly addictive psychostimulant drug that injures monoaminergic neurons and results in behavioral impairments in humans and animals. Although evidence exists for changes in cortical volume, metabolism, and blood oxygenation levels in human mAMPH abusers, animal models have instead emphasized this drug's long-lasting influence on ascending monoaminergic (dopamine, serotonin) projections. The aim of this study was to investigate cortical and subcortical function in rats long after administration of a single-day mAMPH regimen known to damage monoaminergic systems, at a time point when behavioral impairments are still evident. Rats were given either saline or a neurotoxic (4 x 4 mg/kg, sc) mAMPH regimen. Five weeks later, they were given pharmacological treatments that stimulate cortical gene expression: either the dopaminergic agonist apomorphine (3 mg/kg, sc) or the muscarinic acetylcholine agonist pilocarpine (25 mg/kg, ip). Cortical and subcortical immediate early gene (IEG) responses were measured by immunocytochemical analysis of Fos or JunB, protein products of the IEGs, c-fos and junB. Compared with saline-pretreated controls, mAMPH-pretreated animals had about 50-70% fewer Fos- and JunB-immunoreactive cells in anterior cingulate, infralimbic, orbital, somatosensory, and rhinal cortices as well as caudate-putamen and nucleus accumbens, 90 min after apomorphine challenge. By contrast, mAMPH-pretreated rats had no reductions in the numbers of Fos or JunB-positive cells following pilocarpine challenge. This study demonstrates the profound and enduring effects of mAMPH administration on dopamine-stimulated cortical function in animals.

Methamphetamine influences on recognition memory: comparison of escalating and single-day dosing regimens

Methamphetamine (mAMPH) is an addictive drug that produces memory and recall impairments in humans. Animals subjected to a binge mAMPH dosing regimen that damages brain dopamine and serotonin terminals show impairments in an object recognition (OR) task. Earlier research demonstrated that preceding a single-day mAMPH binge regimen with several days of increasing mAMPH doses greatly attenuates its neurotoxicity in rats. The escalating dose (ED) paradigm appears to mimic the human pattern of escalating drug intake. The current aim was to test whether an ED plus binge mAMPH regimen produces OR impairments. In addition to its translational value, this experiment helps address whether monoaminergic neurotoxicity accounts for OR impairments seen after mAMPH administration. To further address this issue, a separate experiment investigated both OR impairments and monoamine transporter integrity in groups of rats treated with a range of mAMPH doses during a single day. An ED mAMPH regimen attenuated the acute hyperthermic response to the subsequent mAMPH binge and prevented the OR impairments and reductions in [125 I]RTI-55 binding to monoamine transporters in striatum, hippocampus (HC), and perirhinal cortex (pRh) that otherwise occur 1 week after the mAMPH binge. Single-day mAMPH regimens (4 x 1mg/kg to 4 x 4 mg/kg, s.c.) dose-dependently produced acute hyperthermia and, 1 week post-mAMPH, produced dose-dependent impairments in OR and reductions in monoamine transporter binding. The OR impairments of single-day mAMPH-treated rats correlated with monoaminergic transporter loss in ventral caudate-putamen, HC, and pRh. In aggregate, these findings suggest a correspondence between mAMPH-induced monoaminergic injury and the resulting OR deficits.

Methamphetamine-induced neural and cognitive changes in rodents

AIMS

Although psychostimulant drug abuse carries with it several potential health risks, the chronic abuse of amphetamines carries the danger of permanent brain injury. The purpose of these experiments is to develop animal models to understand the long-lasting influences of methamphetamine exposure on cerebral cortex and cognitive function.

METHODS

The approach taken is to administer a regimen of methamphetamine known to be neurotoxic to dopamine and serotonin nerve terminals in the rat, and to investigate the influences of that dosing regimen on (i) cortical neuron integrity and function using anatomical stains and (ii) novel object recognition memory.

RESULTS

In rodents, repeated administration of methamphetamine during a single day produces long-lasting damage to striatal dopamine and forebrain serotonin terminals as well as degeneration of somatosensory cortical neurons. The degeneration of somatosensory cortical neurons may represent only the most visible form of long-term deleterious effects on cerebral cortex, as exposure of rats to methamphetamine can reduce the immediate early gene responses of neurons in widespread cortical areas, even long after exposure to the drug. Together with the death and long-lasting functional impairments of cortical neurons, rats exposed to methamphetamine have impaired cognitive function. When tested for object recognition memory, methamphetamine-treated rats show deficiencies lasting for at least 3 weeks after drug exposure.

CONCLUSIONS

Using a rodent model, these findings provide an avenue to study the cortical influences of methamphetamine and their cognitive sequelae.

Effects of hippocampal lesions on the monkey's ability to learn large sets of object-place associations

Earlier studies found that recognition memory for object-place associations was impaired in patients with relatively selective hippocampal damage (Vargha-Khadem et al., Science 1997; 277:376-380), but was unaffected after selective hippocampal lesions in monkeys (Malkova and Mishkin, J Neurosci 2003; 23:1956-1965). A potentially important methodological difference between the two studies is that the patients were required to remember a set of 20 object-place associations for several minutes, whereas the monkeys had to remember only two such associations at a time, and only for a few seconds. To approximate more closely the task given to the patients, we trained monkeys on several successive sets of 10 object-place pairs each, with each set requiring learning across days. Despite the increased associative memory demands, monkeys given hippocampal lesions were unimpaired relative to their unoperated controls, suggesting that differences other than set size and memory duration underlie the different outcomes in the human and animal studies.

A sensitizing regimen of methamphetamine causes impairments in a novelty preference task of object recognition

A neurotoxic regimen of methamphetamine impairs object recognition (OR) in rats. The present study investigated whether neurotoxicity is a necessary component of methamphetamine's effect on OR. Animals were exposed to a sensitizing regimen of methamphetamine, and were tested for OR one week, and locomotor behavior two weeks, later. Quantitative autoradiography was used to measure [(125)I]RTI-55 binding to forebrain dopaminergic and serotonergic transporters. Methamphetamine treatment produced significant OR impairments (and increased locomotion), without reducing dopamine or serotonin transporter binding. This study supports the conclusion that factors other than monoamine terminal injury contribute to the methamphetamine-induced cognitive impairments.

Impaired object recognition memory following methamphetamine, but not p-chloroamphetamine- or d-amphetamine-induced neurotoxicity

Repeated moderate doses of methamphetamine (mAMPH) damage forebrain monoaminergic terminals and nonmonoaminergic cells in somatosensory cortex, and impair performance in a novelty preference task of object recognition (OR). This study aimed to determine whether the memory deficit seen after a neurotoxic mAMPH regimen results from damage to dopamine (DA) and/or serotonin (5-HT) terminals. Animals were given a neurotoxic regimen of mAMPH, p-chloroamphetamine (PCA, preferentially damages 5-HT terminals), d-amphetamine (d-AMPH, preferentially damages DA terminals), or saline. After 1 week, animals were trained and tested for OR memory. Rats treated with mAMPH showed no recognition memory during the short-term memory (STM) test, whereas both PCA- and d-AMPH-treated rats showed OR STM scores comparable to controls. After behavioral testing, the specificity of monoaminergic lesions was determined by postmortem [125I]RTI-55 binding to dopamine (DAT) and serotonin (SERT) transporter proteins. Tissue from a separate group of animals killed 3 days after drug treatment was processed for Fluoro-Jade (F-J) fluorescence histochemistry to detect damaged cortical neurons. mAMPH-treated rats showed reductions in striatal DAT and hippocampal (HC) and perirhinal (pRh) SERT, as well as degeneration of neurons in primary somatosensory cortex. In PCA-treated rats, HC and pRh SERT were substantially depleted, but striatal DAT and cortical neuron survival were unaffected. By contrast, d-AMPH-treated animals showed marked depletions in striatal DAT and cortical neurodegeneration, but HC and pRh SERT were unaffected. This pattern of results indicates that no single feature of mAMPH-induced neurotoxicity is sufficient to produce the OR impairments seen after mAMPH treatment.

Selection of peptides with semiconductor binding specificity for directed nanocrystal assembly

In biological systems, organic molecules exert a remarkable level of control over the nucleation and mineral phase of inorganic materials such as calcium carbonate and silica, and over the assembly of crystallites and other nanoscale building blocks into complex structures required for biological function. This ability to direct the assembly of nanoscale components into controlled and sophisticated structures has motivated intense efforts to develop assembly methods that mimic or exploit the recognition capabilities and interactions found in biological systems. Of particular value would be methods that could be applied to materials with interesting electronic or optical properties, but natural evolution has not selected for interactions between biomolecules and such materials. However, peptides with limited selectivity for binding to metal surfaces and metal oxide surfaces have been successfully selected. Here we extend this approach and show that combinatorial phage-display libraries can be used to evolve peptides that bind to a range of semiconductor surfaces with high specificity, depending on the crystallographic orientation and composition of the structurally similar materials we have used. As electronic devices contain structurally related materials in close proximity, such peptides may find use for the controlled placement and assembly of a variety of practically important materials, thus broadening the scope for 'bottom-up' fabrication approaches.

Molecular cloning and characterization of lustrin A, a matrix protein from shell and pearl nacre of Haliotis rufescens

A specialized extracellular matrix of proteins and polysaccharides controls the morphology and packing of calcium carbonate crystals and becomes occluded within the mineralized composite during formation of the molluscan shell and pearl. We have cloned and characterized the cDNA coding for Lustrin A, a newly described matrix protein from the nacreous layer of the shell and pearl produced by the abalone, Haliotis rufescens, a marine gastropod mollusc. The full-length cDNA is 4,439 base pairs (bp) long and contains an open reading frame coding for 1,428 amino acids. The deduced amino acid sequence reveals a highly modular structure with a high proportion of Ser (16%), Pro (14%), Gly (13%), and Cys (9%). The protein contains ten highly conserved cysteine-rich domains interspersed by eight proline-rich domains; a glycine- and serine-rich domain lies between the two cysteine-rich domains nearest the C terminus, and these are followed by a basic domain and a C-terminal domain that is highly similar to known protease inhibitors. The glycine- and serine-rich domain and at least one of the proline-rich domains show sequence similarity to proteins of two extracellular matrix superfamilies (one of which also is involved in the mineralized matrixes of bone, dentin, and avian eggshell). The arrangement of alternating cysteine-rich domains and proline-rich domains is strikingly similar to that found in frustulins, the proteins that are integral to the silicified cell wall of diatoms. Its modular structure suggests that Lustrin A is a multifunctional protein, whereas the occurrence of related sequences suggest it is a member of a multiprotein family.

Modification of calcite crystal growth by abalone shell proteins: an atomic force microscope study

A family of soluble proteins from the shell of Haliotis rufescens was introduced over a growing calcite crystal being scanned in situ by an atomic force microscope (AFM). Atomic step edges on the crystal surface were altered in shape and speed of growth by the proteins. Proteins attached nonuniformly to the surface, indicating different interactions with crystallographically different step edges. The observed changes were consistent with the habit modification induced by this family of proteins, as previously observed by optical microscopy. To facilitate further studies in this area, AFM techniques and certain AFM imaging artifacts are discussed in detail.

Copulatory behavior of adult tamarins (Saguinus fuscicollis) castrated as neonates or juveniles: effect of testosterone treatment

The sexual interactions of Saguinus fuscicollis males castrated as neonates, at 37 days of age, or prepubertally with adult intact females were studied. Prepubertally castrated males were observed while receiving testosterone, and while being treated with saline. Males castrated neonatally or at 37 days of age were observed while receiving testosterone. Neonatal castrates had previously been studied without hormone treatment and therefore no control condition was included for these animals. Prepubertally castrated males showed Mounts, Mounts with Thrusts, and Sexual Tongue Flicking when treated with saline only. In three of the four males, all measures of sexual behavior increased with testosterone treatment. Neonatally castrated males had failed to display any mounting or thrusting without testosterone treatment during a previous study. During the present study, three of the four males did not respond to testosterone treatment with sexual behavior. The fourth male and one male castrated at 37 days of age displayed some sexual behavior. These results suggest that most neonatally castrated males are not able to respond to testosterone with the activation of copulatory behavior. The findings are consistent with the hypothesis that in callitrichids the sensitive period for behavioral differentiation is shifted into neonatal life. However, some neonatally castrated males show a weak response to testosterone. This may reflect an extended and perhaps partially prenatal period of sensitivity.

Computerized pattern recognition: a new technique for the analysis of chemical communication

Computerized pattern recognition techniques can be applied to the study of complex chemical communication systems. Analysis of high resolution gas chromatographic concentration patterns of the major volatile components of the scent marks of a South American primate, Saguinus fuscicollis, demonstrates that the concentration patterns can be used to predict the gender and subspecies of unknown donors.