Trainee Autonomy and Supervision in the Modern Clinical Learning Environment: A Mixed-Methods Study of Faculty and Trainee Perspectives.

Background: Balancing autonomy and supervision during medical residency is important for trainee development while ensuring patient safety. In the modern clinical learning environment, tension exists when this balance is skewed. This study aimed to understand the current and ideal states of autonomy and supervision, then describe the factors that contribute to imbalance from both trainee and attending perspectives. Methods: A mixed-methods design included surveys and focus groups of trainees and attendings at three institutionally affiliated hospitals between May 2019-June 2020. Survey responses were compared using chi-square tests or Fisher's exact tests. Open-ended survey and focus group questions were analyzed using thematic analysis. Results: Surveys were sent to 182 trainees and 208 attendings; 76 trainees (42%) and 101 attendings (49%) completed the survey. Fourteen trainees (8%) and 32 attendings (32%) participated in focus groups. Trainees perceived the current culture to be significantly more autonomous than attendings; both groups described an "ideal" culture as more autonomous than the current state. Focus group analysis revealed five core contributors to the balance of autonomy and supervision: attending-, trainee-, patient-, interpersonal-, and institutional-related factors. These factors were found to be dynamic and interactive with each other. Additionally, we identified a cultural shift in how the modern inpatient environment is impacted by increased hospitalist attending supervision and emphasis on patient safety and health system improvement initiatives. Conclusions: Trainees and attendings agree that the clinical learning environment should favor resident autonomy and that the current environment does not achieve the ideal balance. There are several factors contributing to autonomy and supervision, including attending-, resident-, patient-, interpersonal-, and institutional-related. These factors are complex, multifaceted, and dynamic. Cultural shifts towards supervision by primarily hospitalist attendings and increased attending accountability for patient safety and systems improvement outcomes further impacts trainee autonomy.

Comprehensive Assessment of Clinical Learning Environments to Drive Improvement: Lessons Learned from a Pilot Program.

Problem: Recognition of the importance of clinical learning environments (CLEs) in health professions education has led to calls to evaluate and improve the quality of such learning environments. As CLEs sit at the crossroads of education and healthcare delivery, leadership from both entities should share the responsibility and accountability for this work. Current data collection about the experience and outcomes for learners, faculty, staff, and patients tends to occur in fragmented and siloed ways, and available tools to assess clinical learning environments are limited in scope. In addition, from an organizational perspective oversight of education and patient care is often done by separate entities, and not infrequently is there a sense of competing interests. Intervention: We aimed to design and pilot a holistic approach to assessment and review of CLEs and establish whether such a formative assessment process could be used to engage stakeholders from education, departmental, and health systems leadership in improvement of CLEs. Utilizing concepts of implementation science, we planned and executed a holistic assessment process for CLEs, monitored the impact of the assessment, and reflected on the process. We focused the assessment on four pillars characterizing exemplary learning environments: 1) Environment is inclusive, promotes diversity and collaboration; 2) Focus on continuous quality improvement; 3) Alignment between work and learning; and 4) Integration of education and healthcare mission. Context: At our institution, medical trainees rotate through several different health systems, but clinical and educational leadership converge at the departmental level. We therefore focused this proof-of-concept project on two large clinical departments at our institution, centering on medical learners from undergraduate and graduate medical education. For each department, a small team of champions helped create an assessment grid based on the four pillars and identified existing quantitative evaluation data sources. Champions subsequently collected qualitative data through observations, focus groups, and interviews to fill any gaps in available quantitative data. Impact: The project teams shared reports summarizing findings and recommendations with departmental, clinical, and educational leadership. Subsequent meetings with these stakeholders led to actionable plans for improvement as well as sustained structures for collaborative work between the different stakeholder groups. Lessons Learned: This project demonstrated the feasibility and effectiveness of collating, analyzing, and sharing data from various sources in engaging different stakeholder groups to initiate actionable improvement plans. Collating quantitative data from existing resources was a powerful way to demonstrate common issues in CLEs, and qualitative data provided further detail to inform improvement initiatives. Other institutions can adapt this approach to guide assessment and quality improvement of CLEs. As a next step, we are creating a comprehensive learning environment scorecard to allow for comparison of clinical learning environment quality across institutions and over time.

Goals, challenges, and next steps in transdisciplinary fisheries research: perspectives and experiences from early-career researchers.

Fisheries are highly complex social-ecological systems that often face 'wicked' problems from unsustainable resource management to climate change. Addressing these challenges requires transdisciplinary approaches that integrate perspectives across scientific disciplines and knowledge systems. Despite widespread calls for transdisciplinary fisheries research (TFR), there are still limitations in personal and institutional capacity to conduct and support this work to the highest potential. The viewpoints of early career researchers (ECRs) in this field can illuminate challenges and promote systemic change within fisheries research. This paper presents the perspectives of ECRs from across the globe, gathered through a virtual workshop held during the 2021 World Fisheries Congress, on goals, challenges, and future potential for TFR. Big picture goals for TFR were guided by principles of co-production and included (i) integrating transdisciplinary thinking at all stages of the research process, (ii) ensuring that research is inclusive and equitable, (iii) co-creating knowledge that is credible, relevant, actionable, and impactful, and (iv) consistently communicating with partners. Institutional inertia, lack of recognition of the extra time and labour required for TFR, and lack of skill development opportunities were identified as three key barriers in conducting TFR. Several critical actions were identified to help ECRs, established researchers, and institutions reach these goals. We encourage ECRs to form peer-mentorship networks to guide each other along the way. We suggest that established researchers ensure consistent mentorship while also giving space to ECR voices. Actions for institutions include retooling education programs, developing and implementing new metrics of impact, and critically examining individualism and privilege in academia. We suggest that the opportunities and actions identified here, if widely embraced now, can enable research that addresses complex challenges facing fishery systems contributing to a healthier future for fish and humans alike.

Characterization of caspase-2 inhibitors based on specific sites of caspase-2-mediated proteolysis.

Since the discovery of the caspase-2 (Casp2)-mediated ∆tau314 cleavage product and its associated impact on tauopathies such as Alzheimer's disease, the design of selective Casp2 inhibitors has become a focus in medicinal chemistry research. In the search for new lead structures with respect to Casp2 selectivity and drug-likeness, we have taken an approach by looking more closely at the specific sites of Casp2-mediated proteolysis. Using seven selected protein cleavage sequences, we synthesized a peptide series of 53 novel molecules and studied them using in vitro pharmacology, molecular modeling, and crystallography. Regarding Casp2 selectivity, AcITV(Dab)D-CHO (23) and AcITV(Dap)D-CHO (26) demonstrated the best selectivity (1-6-fold), although these trends were only moderate. However, some analogous tetrapeptides, most notably AcDKVD-CHO (45), showed significantly increased Casp3 selectivities (>100-fold). Tetra- and tripeptides display decreased or no Casp2 affinity, supporting the assumption that a motif of five amino acids is required for efficient Casp2 inhibition. Overall, the results provide a reasonable basis for the development of both selective Casp2 and Casp3 inhibitors.

Structure-Based Design and Biological Evaluation of Novel Caspase-2 Inhibitors Based on the Peptide AcVDVAD-CHO and the Caspase-2-Mediated Tau Cleavage Sequence YKPVD314.

Alzheimer's disease (AD) was first described by Alois Alzheimer over 100 years ago, but there is still no overarching theory that can explain its cause in detail. There are also no effective therapies to treat either the cause or the associated symptoms of this devastating disease. A potential approach to better understand the pathogenesis of AD could be the development of selective caspase-2 (Casp2) probes, as we have shown that a Casp2-mediated cleavage product of tau (Δtau314) reversibly impairs cognitive and synaptic function in animal models of tauopathies. In this article, we map out the Casp2 binding site through the preparation and assay of a series of 35 pentapeptide inhibitors with the goal of gaining selectivity against caspase-3 (Casp3). We also employed computational docking methods to understand the key interactions in the binding pocket of Casp2 and the differences predicted for binding at Casp3. Moreover, we crystallographically characterized the binding of selected pentapeptides with Casp3. Furthermore, we engineered and expressed a series of recombinant tau mutants and investigated them in an in vitro cleavage assay. These studies resulted in simple peptidic inhibitors with nanomolar affinity, for example, AcVDV(Dab)D-CHO (24) with up to 27.7-fold selectivity against Casp3. Our findings provide a good basis for the future development of selective Casp2 probes and inhibitors that can serve as pharmacological tools in planned in vivo studies and as lead compounds for the design of bioavailable and more drug-like small molecules.

Standardized Transfer Process for a Neurointensive Care Unit and Assessment of Patient Bounceback.

BACKGROUND: Patients who require readmission to an intensive care unit (ICU) after transfer to a lower level of care ("bounceback") suffer from increased mortality and longer hospital stays. We aimed to create a multifaceted standardized transfer process for patients moving from the neurointensive care unit (neuro-ICU) to a lower level of care. We hypothesized that this process would lead to improvement in provider-rated safety and a decreased rate of bouncebacks to the neuro-ICU after transfer. METHODS: The study took place at the Hospital of the University of Pennsylvania from October 2018 to October 2020. A standardized five-step transfer process was created and implemented for transferring patients from the neuro-ICU to a lower level of care. Patient care providers completed a survey before and after implementation of the protocol to assess a variety of components related to safety concerns when transferring patients. The rate of bouncebacks pre and post intervention was calculated by using a two-sample Wilcoxon rank-sum test, and disposition at discharge was calculated by using Fisher's exact test. RESULTS: Of the 1176 total patient transfers out of the neuro-ICU, 29 patients bounced back within 48 h. The average age of patients who bounced back was 63.3 years old, with a similar distribution among men and women. The most common reason for bounceback was respiratory distress, followed by cardiac arrhythmia, stroke, and sepsis. Implementation of the standardized process led to a decrease in provider-rated concern of overall safety (5 to 3, p = 0.008). There was improvement in transfer delays due to bed availability (3 to 4.5, p = 0.020), identification of high-risk patients (5 to 6, p = 0.021), patient assignment to the appropriate level of care (5 to 6, p = 0.019), and use of the electronic medical record handoff indicator (5 to 6, p = 0.003). There was no statistically significant difference in terms of patient bounceback rate after implementation of the process (2.4% vs. 2.5%, p = 1.00) or patient disposition at discharge (p = 0.553). CONCLUSIONS: Patients who bounceback to the neuro-ICU within 48 h had an increased length of hospital stay, had an increased length of ICU stay, and were more likely to be intubated for more than 96 h. Implementation of a standardized five-step transfer process from the neuro-ICU to a lower level of care resulted in improvement in multiple provider-rated safety outcomes and identification of high-risk patients but led to no difference in the patient bounceback rate or patient disposition at discharge.

Mindful Parenting: A Behavioral Tool for Parent Well-Being.

Parents often suffer from conditions such as stress and depression due to the high demands of parenting. In particular, parenting children with some form of developmental disability may bring about increased maladaptive behaviors that may increase daily parenting stressors. The fast-spreading repercussions of the COVID-19 pandemic have left millions of parents across the globe to deal with various stressors in isolation. Recent studies have demonstrated the effectiveness of mindfulness as an intervention for targeting individuals' behaviors such as aggression, self-injurious behavior, and noncompliance while increasing overall well-being and happiness levels. Significant decreases in target behaviors are noted across studies, as well as increases in parent satisfaction and well-being. This study reviews the use of mindfulness within the scope of behavior analysis as a tool that can be quickly implemented to support parents not only through this crisis but also throughout parenthood in general.

Journeying through the Field of Medicinal Chemistry: Perspectives from Graduate Researchers.

The training of new medicinal chemists is vital to the future of the field, and as graduate students at this critical stage, we are uniquely positioned to comment on our training. Herein, we discuss the perspectives from graduate researchers before, during, and after graduate school by utilizing survey data obtained from five medicinal chemistry programs in the Midwest and recent alumni of the University of Minnesota. We also reflect on the female perspective within the field of medicinal chemistry. Finally, we offer recommendations to both students and faculty in the hopes of helping future generations succeed in the field.

A Preliminary Analysis of Mastery Criterion Level: Effects on Response Maintenance.

Educators use a mastery criterion to evaluate skill acquisition programming for children with autism and other developmental disabilities; however, to the best of our knowledge, there has been no research evaluating how the mastery criterion level of accuracy affects the maintenance of those responses. This study investigated the effects of 3 skill acquisition mastery criterion levels (50%, 80%, and 90% accuracy) on response maintenance. Following mastery of a set of skills, maintenance was evaluated once a week for 3 to 4 weeks. Three elementary school-age children diagnosed with autism participated. Overall, the outcomes suggested that higher mastery criterion levels (90% correct) produced higher levels of maintenance responding. Additional research in this area is needed to clarify how different parameters of mastery criterion affect the generality of skills.

Increased troponin I is associated with fatal outcome in acquired thrombotic thrombocytopenic purpura.

Thrombotic thrombocytopenic purpura (TTP) has >90% mortality without therapeutic plasma exchange (TPE). Despite TPE, approximately 10% of patients still die, presumably from cardiac ischemia. We sought clinical or laboratory parameters associated with death by reviewing the records of all patients hospitalized with acquired TTP in our institution for 10 years, and collect demographics and results for hemoglobin, platelet count, creatinine, lactate dehydrogenase, transaminases, total bilirubin, creatinine kinase (CK), CK-MB, and troponin I. Sixty-eight patients were admitted 88 times, and 11 died. Survivors and non-survivors were similar in terms of sex, ethnicity, thrombocytopenia, and degree of anemia at presentation, while the latter were older, had worse renal function and higher CK, CK-MB, and troponin I (univariate analysis). However, only troponin I remained significant on multivariate analyses. We propose that patients with TTP should be monitored with troponin I to detect significant myocardial ischemia that could predict death despite TPE.

Biobreeding rat islets exhibit reduced antioxidative defense and N-acetyl cysteine treatment delays type 1 diabetes.

Islet-level oxidative stress has been proposed as a trigger for type 1 diabetes (T1D), and release of cytokines by infiltrating immune cells further elevates reactive oxygen species (ROS), exacerbating ß cell duress. To identify genes/mechanisms involved with diabetogenesis at the ß cell level, gene expression profiling and targeted follow-up studies were used to investigate islet activity in the biobreeding (BB) rat. Forty-day-old spontaneously diabetic lymphopenic BB DRlyp/lyp rats (before T cell insulitis) as well as nondiabetic BB DR+/+ rats, nondiabetic but lymphopenic F344lyp/lyp rats, and healthy Fischer (F344) rats were examined. Gene expression profiles of BB rat islets were highly distinct from F344 islets and under-expressed numerous genes involved in ROS metabolism, including glutathione S-transferase (GST) family members (Gstm2, Gstm4, Gstm7, Gstt1, Gstp1, and Gstk1), superoxide dismutases (Sod2 and Sod3), peroxidases, and peroxiredoxins. This pattern of under-expression was not observed in brain, liver, or muscle. Compared with F344 rats, BB rat pancreata exhibited lower GST protein levels, while plasma GST activity was found significantly lower in BB rats. Systemic administration of the antioxidant N-acetyl cysteine to DRlyp/lyp rats altered abundances of peripheral eosinophils, reduced severity of insulitis, and significantly delayed but did not prevent diabetes onset. We find evidence of ß cell dysfunction in BB rats independent of T1D progression, which includes lower expression of genes related to antioxidative defense mechanisms during the pre-onset period that may contribute to overall T1D susceptibility.

BB rat Gimap gene expression in sorted lymphoid T and B cells.

AIMS: The Gimap gene family has been shown to be integral to T cell survival and development. A frameshift mutation in Gimap5, one of seven members of the Gimap family, results in lymphopenia and is a prerequisite for spontaneous type 1 diabetes (T1D) in the BioBreeding (BB) rat. While not contributing to lymphopenia, the Gimap family members proximal to Gimap5, encompassed within the Iddm39 quantitative trait locus (QTL), have been implicated in T1D. We hypothesized that expression of the Gimap family members within the Iddm39 QTL, during thymocyte development as well as in peripheral T and B cells contribute to T1D. MAIN METHODS: Cell sorted subpopulations were analyzed by quantitative real time (qRT) PCR. KEY FINDINGS: Gimap4 expression was reduced in DR.(lyp/lyp) rat double negative, double positive and CD8 single positive (SP) thymocytes while expression of Gimap8, Gimap6, and Gimap7 was reduced only in CD8 SP thymocytes. Interestingly, expression of the entire Gimap gene family was reduced in DR.(lyp/lyp) rat peripheral T cells compared to non-lymphopenic, non-diabetic DR.(+/+) rats. With the exception of Gimap6, the Gimap family genes were not expressed in B cells from spleen and mesenteric lymph node (MLN). Expression of Gimap9 was only detected in hematopoietic cells of non B cell lineage such as macrophage, dendritic or NK cells. SIGNIFICANCE: These results suggest that lack of the Gimap5 protein in the DR.(lyp/lyp) congenic rat was associated with impaired expression of the entire family of Gimap genes and may regulate T cell homeostasis in the peripheral lymphoid organs.

Digital tomosynthesis for respiratory gated liver treatment: clinical feasibility for daily image guidance.

PURPOSE: Breath-hold (BH) treatment minimizes internal target volumes (ITV) when treating sites prone to motion. Digital tomosynthesis (DTS) imaging has advantages over cone-beam CT (CBCT) for BH imaging: BH-DTS scan can be completed during a single breath-hold, whereas BH-CBCT is usually acquired by parsing the gantry rotation into multiple BH segments. This study evaluates the localization accuracy of DTS for BH treatment of liver tumors. METHODS: Both planning CT and on-board DTS/CBCT images were acquired under BH, using the planning CT BH window as reference. Onboard imaging data sets included two independent DTS orientations (coronal and sagittal), and CBCT images. Soft tissue target positioning was measured by each imaging modality and translated into couch shifts. Performance of the two DTS orientations was evaluated by comparing target positioning with the CBCT benchmark, determined by two observers. RESULTS: Image data sets were collected from thirty-eight treatment fractions (14 patients). Mean differences between the two DTS methods and the CBCT method were <1 mm in all directions (except the lateral direction with sagittal-DTS: 1.2 mm); the standard deviation was in the range of 2.1-3.5 mm for all techniques. The Pearson correlation showed good interobserver agreement for the coronal-DTS (0.72-0.78). The interobserver agreement for the sagittal-DTS was good for the in-plane directions (0.70-0.82), but poor in the out-of-plane direction (lateral, 0.26). CONCLUSIONS: BH-DTS may be a simpler alternative to BH-CBCT for onboard soft tissue localization of the liver, although the precision of DTS localization appears to be somewhat lower because of the presence of subtle out-of-plane blur.

Prolonged survival and improved glycemia in BioBreeding diabetic rats after early sustained exposure to glucagon-like peptide 1.

BACKGROUND: Type 1 diabetes (T1D) in both humans and BioBreeding (BB) rats is an autoimmune disease that results in complete destruction of islets and insulin dependency for life. Glucagon-like peptide 1 (GLP-1) promotes beta cell proliferation and neogenesis and has a potent insulinotropic effect. We hypothesized that the expression of GLP-1 before disease onset would increase islet mass, delay diabetes and prolong survival of BB rats. METHODS: Vascular smooth muscle cells retrovirally transduced to secrete GLP-1 were seeded into TheraCyte encapsulation devices, implanted subcutaneously, and rats were monitored for diabetes. RESULTS: In untreated control rats, plasma GLP-1 levels were 34.5-39.5 pmol/l, whereas, in treated rats, plasma levels were elevated, in the range 90-250.4 pmol/l. Hypoglycemia was not detected and this was anticipated from the glucose-regulated action of GLP-1. Diabetes onset (mean + or - SEM) in untreated rats occurred at 56.5 + or - 0.6 days (n = 6) and, in GLP-1-treated rats, was delayed until 76.4 + or - 3.3 days (n = 5) (p < 0.001). After disease onset, untreated control rats showed a rapid weight loss and elevated blood glucose (>650 mg/dl) and did not survive beyond 11 days. At 5 days after diabetes onset, insulin-secreting islets were absent in untreated rats. By contrast, treated rats maintained weight for up to 143 days of age and showed insulin-secreting beta cells. CONCLUSIONS: Sustained GLP-1 expression delivered by encapsulated cells before diabetes onset in BB rats showed an improved clinical outcome, suggesting the potential for treating patients using long lasting GLP-1 analogs.

Differential effects of leptin receptor mutation on male and female BBDR Gimap5-/Gimap5- spontaneously diabetic rats.

Rodents homozygous for autosomal leptin receptor gene mutations not only become obese, insulin resistant, and hyperleptinemic but also develop a dysregulated immune system. Using marker-assisted breeding to introgress the Koletsky rat leptin receptor mutant (lepr-/lepr-), we developed a novel congenic BBDR.(lepr-/lepr-) rat line to study the development of obesity and type 2 diabetes (T2D) in the BioBreeding (BB) diabetes-resistant (DR) rat. While heterozygous lepr (-/+) or homozygous (+/+) BBDR rats remained lean and metabolically normal, at 3 wk of age all BBDR.(lepr-/lepr-) rats were obese without hyperglycemia. Between 45 and 70 days of age, male but not female obese rats developed T2D. We had previously developed congenic BBDR.(Gimap5-/Gimap5-) rats, which carry an autosomal frameshift mutation in the Gimap5 gene linked to lymphopenia and spontaneous development of type 1 diabetes (T1D) without sex differences. Because the autoimmune-mediated destruction of pancreatic islet beta-cells may be affected not only by obesity but also by the absence of leptin receptor signaling, we next generated BBDR.(lepr-/lepr-,Gimap5-/Gimap5-) double congenic rats carrying the mutation for Gimap5 and T1D as well as the Lepr mutation for obesity and T2D. The hyperleptinemia rescued end-stage islets in BBDR.(lepr-/lepr-,Gimap5-/Gimap5-) congenic rats and induced an increase in islet size in both sexes, while T1D development was delayed and reduced only in females. These results demonstrate that obesity and T2D induced by introgression of the Koletsky leptin receptor mutation in the BBDR rat result in islet expansion associated with protection from T1D in female but not male BBDR.(lepr-/lepr-,Gimap5-/Gimap5-) congenic rats. BBDR.(lepr-/lepr-,Gimap5-/Gimap5-) congenic rats should prove valuable to study interactions between lack of leptin receptor signaling, obesity, and sex-specific T2D and T1D.

Sequence variation and expression of the Gimap gene family in the BB rat.

Positional cloning of lymphopenia (lyp) in the BB rat revealed a frameshift mutation in Gimap5, a member of at least seven related GTPase Immune Associated Protein genes located on rat chromosome 4q24. Our aim was to clone and sequence the cDNA of the BB diabetes prone (DP) and diabetes resistant (DR) alleles of all seven Gimap genes in the congenic DR.lyp rat line with 2 Mb of BB DP DNA introgressed onto the DR genetic background. All (100%) DR.(lyp/lyp) rats are lymphopenic and develop type 1 diabetes (T1D) by 84 days of age while DR.(+/+) rats remain T1D and lyp resistant. Among the seven Gimap genes, the Gimap5 frameshift mutation, a mutant allele that produces no protein, had the greatest impact on lymphopenia in the DR.(lyp/lyp) rat. Gimap4 and Gimap1 each had one amino acid substitution of unlikely significance for lymphopenia. Quantitative RT-PCR analysis showed a reduction in expression of all seven Gimap genes in DR.(lyp/lyp) spleen and mesenteric lymph nodes when compared to DR.(+/+). Only four; Gimap1, Gimap4, Gimap5, and Gimap9 were reduced in thymus. Our data substantiates the Gimap5 frameshift mutation as the primary defect with only limited contributions to lymphopenia from the remaining Gimap genes.

Analysis of the rat Iddm14 diabetes susceptibility locus in multiple rat strains: identification of a susceptibility haplotype in the Tcrb-V locus.

Iddm14 (formerly Iddm4) is a non-MHC-linked genetic locus associated with autoimmune diabetes. Its effects have been well-documented in BB-derived rats in which diabetes is either induced by immunologic perturbation or occurs spontaneously. The role of Iddm14 in non-BB rat strains is unknown. Our goal was to extend the analysis of Iddm14 in new diabetes-susceptible strains and to identify candidate genes in the rat Iddm14 diabetes susceptibility locus that are common to these multiple diabetic strains. To determine if Iddm14 is important in strains other than BB, we first genotyped a (LEW.1WR1 x WF)F2 cohort in which diabetes was induced by perturbation with polyinosinic:polycytidylic acid. We found that Iddm14 is a major determinant of diabetes susceptibility in LEW.1WR1 rats. We then used nucleotide sequencing to establish a strain distribution pattern of polymorphisms (insertions, deletions, and single nucleotide polymorphisms [SNPs]) that predicts susceptibility to diabetes in a panel of inbred and congenic rats. Using the positional information from the congenic strains and the new linkage data, we identified a susceptibility haplotype in the T-cell receptor Vbeta chain (Tcrb-V) locus. This haplotype includes Tcrb-V13, which is identical in five susceptible strains but different in resistant WF and F344 rats. We conclude that Iddm14 is a powerful determinant of both spontaneous and induced autoimmune diabetes in multiple rat strains, and that Tcrb-V13 SNPs constitute a haplotype of gene elements that may be critical for autoimmune diabetes in rats.

Treatment of diabetic rats with encapsulated islets.

Immunoprotection of islets using bioisolator systems permits introduction of allogeneic cells to diabetic patients without the need for immunosuppression. Using TheraCyte immunoisolation devices, we investigated two rat models of type 1 diabetes mellitus (T1DM), BB rats and rats made diabetic by streptozotocin (STZ) treatment. We chose to implant islets after the onset of diabetes to mimic the probable treatment of children with T1DM as they are usually diagnosed after disease onset. We encapsulated 1000 rat islets and implanted them subcutaneously (SQ) into diabetic biobreeding (BB) rats and STZ-induced diabetic rats, defined as two or more consecutive days of blood glucose>350 mg/dl. Rats were monitored for weight and blood glucose. Untreated BB rats rapidly lost weight and were euthanized at >20% weight loss that occurred between 4 and 10 days from implantation. For period of 30-40 days following islet implantation weights of treated rats remained steady or increased. Rapid weight loss occurred after surgical removal of devices that contained insulin positive islets. STZ-treated rats that received encapsulated islets showed steady weight gain for up to 130 days, whereas untreated control rats showed steady weight loss that achieved >20% at around 55 days. Although islet implants did not normalize blood glucose, treated rats were apparently healthy and groomed normally. Autologous or allogeneic islets were equally effective in providing treatment. TheraCyte devices can sustain islets, protect allogeneic cells from immune attack and provide treatment for diabetic-mediated weight loss in both BB rats and STZ-induced diabetic rats.

Decreased core temperature and increased beta(3)-adrenergic sensitivity in diabetes-prone BB rats.

BACKGROUND: Diabetes-prone (DP) congenic DR.lyp/lyp BioBreeding (BB) rats all develop Type 1 diabetes between 50 and 81 days of age, while DR.lyp/+ or DR.+/+ BB rats are diabetes resistant (DR). The DP rats display reduced weight gain prior to developing hyperglycemia, implying that metabolic events may precede diabetes onset. We tested the hypothesis that temperature measurements could serve as a physiological marker for the impending onset of hyperglycemia. METHODS: Prior to the onset of hyperglycemia, brain, lower back, and intrascapular brown adipose tissue temperatures were analyzed by thermal signature analysis, which measures infrared emission from tissues. A thermocoupled rectal probe measured core temperature. In addition we performed a beta(3)-adrenergic receptor challenge test with the beta(3)-adrenergic receptor agonist BRL37344. RESULTS: DP rats displayed lower core temperature than DR rats prior to the onset of hyperglycemia. No temperature difference was detected in brain, lower back, or intrascapular brown adipose tissue between DP and DR rats. The beta(3)-adrenergic challenge showed that the rate of temperature increase after administration of BRL37344 was significantly higher (0.005 +/- 0.002 degrees C/min) in DP than in DR rats (P = 0.044). CONCLUSIONS: These studies reveal that the prediabetic DP rats fail to maintain core temperature and that they display increased sensitivity to heat production induced by a beta(3)-adrenergic receptor agonist. These studies suggest that body temperature as a measure of metabolic dysregulation is altered in the prediabetic DP rat prior to the onset of hyperglycemia.

Low-density cells isolated from the rat thymus resemble branched cortical macrophages and have a reduced capability of rescuing double-positive thymocytes from apoptosis in the BB-DP rat.

Biobreeding-diabetes prone (BB-DP) rats spontaneously develop organ-specific autoimmunity and are severely lymphopenic and particularly deficient in ART2(+) regulatory T cells. A special breed, the so-called BB-diabetic-resistant (DR) rats, are not lymphopenic and do not develop organ-specific autoimmunity. The genetic difference between both strains is the lymphopenia (lyp) gene. Intrathymic tolerance mechanisms are important to prevent autoimmunity, and next to thymus epithelial cells, thymus APC play a prominent part in this tolerance. We here embarked on a study to detect defects in thymus APC of the BB-DP rat and isolated thymus APC using a protocol based on the low-density and nonadherent character of the cells. We used BB-DP, BB-DR, wild-type F344, and F344 rats congenic for the lyp gene-containing region. The isolated thymus, nonadherent, low-density cells appeared to be predominantly ED2(+) branched cortical macrophages and not OX62(+) thymus medullary and cortico-medullary dendritic cells. Functionally, these ED2(+) macrophages were excellent stimulators of T cell proliferation, but it is more important that they rescued double-positive thymocytes from apoptosis. The isolated thymus ED2(+) macrophages of the BB-DP and the F344.lyp/lyp rat exhibited a reduced T cell stimulatory capacity as compared with such cells of nonlymphopenic rats. They had a strongly diminished capability of rescuing thymocytes from apoptosis (also of ART2(+) T cells) and showed a reduced Ian5 expression (as lyp/lyp thymocytes do). Our experiments strongly suggest that branched cortical macrophages play a role in positive selection of T cells in the thymus and point to defects in these cells in BB-DP rats.