Psychosocial aspects of diabetes technology.

AIM: To identify key psychosocial research in the domain of diabetes technology. RESULTS: Four trajectories of psychosocial diabetes technology research are identified that characterize research over the past 25 years. Key evidence is reviewed on psychosocial outcomes of technology use as well as psychosocial barriers and facilitating conditions of diabetes technology uptake. Psychosocial interventions that address modifiable barriers and psychosocial factors have proven to be effective in improving glycaemic and self-reported outcomes in diabetes technology users. CONCLUSIONS: Psychosocial diabetes technology research is essential for designing interventions and education programmes targeting the person with diabetes to facilitate optimized outcomes associated with technology uptake. Psychosocial aspects of diabetes technology use and related research will be even more important in the future given the advent of systems for automated insulin delivery and the increasingly widespread digitalization of diabetes care.

Comparative characteristics of older people with type 1 diabetes treated with continuous subcutaneous insulin infusion or insulin injection therapy: data from the German/Austrian DPV registry.

AIM: To compare clinical characteristics and outcomes in adults with type 1 diabetes aged ≥ 60 years using continuous subcutaneous insulin infusion (CSII) vs. insulin injection therapy. Further, to determine the percentage of older adults with type 1 diabetes using CSII. RESEARCH DESIGN AND METHODS: Retrospective study using data of the Diabetes Prospective Follow-up Registry (DPV). Including percentage CSII use from 2008 to 2018, and the characteristics of 9547 individuals extracted from the DPV in March 2019 (N = 1404 CSII; N = 8143 insulin injection therapy). Wilcoxon rank sum tests were used for continuous variables and chi-square tests for categorical variables to compare clinical characteristics of people using CSII vs. insulin injection therapy. Adjusted analyses used generalized linear models to compare diabetes-related outcomes. RESULTS: CSII usage has increased in older adults (from 12% in 2008 to 23% in 2018). After adjustment, CSII was associated with lower HbA1c [60.7 mmol/mol (7.7 ± 0.1%) vs. 62.8% (7.9 ± 0.1%)], lower daily insulin dose (0.49 ± 0.02 vs. 0.61 ± 0.01 IU/kg), fewer days in hospital (8.1 ± 0.12 vs. 11.2 ± 0.11 days/person-year), fewer severe hypoglycaemic events (0.16 ± 0.02 vs. 0.21 ± 0.03 events/person-year) and fewer diabetic ketoacidosis (0.06 ± 0.01 vs. 0.08 ± 0.01 events/person-year). Individuals on CSII showed lower rates of microalbuminuria and also have a diagnosis of depression and neuropathy. CONCLUSIONS: A growing number of older adults are using insulin pumps. Older age in itself should not be seen as a contraindication for CSII.

Intervention studies to foster resilience - A systematic review and proposal for a resilience framework in future intervention studies.

Psychological resilience refers to the phenomenon that many people are able to adapt to the challenges of life and maintain mental health despite exposure to adversity. This has stimulated research on training programs to foster psychological resilience. We evaluated concepts, methods and designs of 43 randomized controlled trials published between 1979 and 2014 which assessed the efficacy of such training programs and propose standards for future intervention research based on recent developments in the field. We found that concepts, methods and designs in current resilience intervention studies are of limited use to properly assess efficacy of interventions to foster resilience. Major problems are the use of definitions of resilience as trait or a composite of resilience factors, the use of unsuited assessment instruments, and inappropriate study designs. To overcome these challenges, we propose 1) an outcome-oriented definition of resilience, 2) an outcome-oriented assessment of resilience as change in mental health in relation to stressor load, and 3) methodological standards for suitable study designs of future intervention studies. Our proposals may contribute to an improved quality of resilience intervention studies and may stimulate further progress in this growing research field.

Focus group study to identify the central facets of fear of hypoglycaemia in people with Type 2 diabetes mellitus.

AIMS: To determine key worries about hypoglycaemia among insulin-using adults with Type 2 diabetes using a focus group approach. METHODS: Thirteen focus groups were conducted in three diabetes outpatient care units and one peer support group was set up, in Germany. A total of 64 insulin-dependent adults with Type 2 diabetes (36.5% women, mean age 65.2 ± 11.0 years) discussed their worries about hypoglycaemia. The qualitative results were assigned into thematic categories using a bottom-up coding procedure. Participants completed the Hypoglycaemia Fear Survey and demographic measures were recorded. The results of the Hypoglycaemia Fear Survey were contrasted with the focus group findings to evaluate how accurately the Hypoglycaemia Fear Survey comprehensively captures features of fear of hypoglycaemia in Type 2 diabetes. RESULTS: Eight themes were identified: 'unconsciousness/death'; 'aloneness/ helplessness', 'fear of hurting somebody'; 'shame'; 'loss of physical control'; 'long-term complications'; 'diabetes self-management issues'; and 'impaired awareness'. A total of 30 participants (46.9%) scored ≥3 on at least one item of the Hypoglycaemia Fear Survey worry subscale, indicating elevated worries. The Hypoglycaemia Fear Survey comprehensively captured all identified themes. Self-efficacy with regard to diabetes self-management seemed to play an important role in fear of hypoglycaemia in Type 2 diabetes. CONCLUSIONS: Given that even subclinical worries can have negative effects on quality of life and diabetes self-management, emphasis should be placed on diabetes education; in particular, to help patients to develop self-efficacy concerning diabetes self-management. The Hypoglycaemia Fear Survey comprehensively captures hypoglycaemia worries in Type 2 diabetes. Additional assessment of self-efficacy might be beneficial to identify people at risk of developing hypoglycaemia worries.

Evidence of estrogenic endocrine disruption in smallmouth and largemouth bass inhabiting Northeast U.S. national wildlife refuge waters: A reconnaissance study.

Intersex as the manifestation of testicular oocytes (TO) in male gonochoristic fishes has been used as an indicator of estrogenic exposure. Here we evaluated largemouth bass (Micropterus salmoides) or smallmouth bass (Micropterus dolomieu) form 19 National Wildlife Refuges (NWRs) in the Northeast U.S. inhabiting waters on or near NWR lands for evidence of estrogenic endocrine disruption. Waterbodies sampled included rivers, lakes, impoundments, ponds, and reservoirs. Here we focus on evidence of endocrine disruption in male bass evidenced by gonad histopathology including intersex or abnormal plasma vitellogenin (Vtg) concentrations. During the fall seasons of 2008-2010, we collected male smallmouth bass (n=118) from 12 sites and largemouth bass (n=173) from 27 sites. Intersex in male smallmouth bass was observed at all sites and ranged from 60% to 100%; in male largemouth bass the range was 0-100%. Estrogenicity, as measured using a bioluminescent yeast reporter, was detected above the probable no effects concentration (0.73ng/L) in ambient water samples from 79% of the NWR sites. Additionally, the presence of androgen receptor and glucocorticoid receptor ligands were noted as measured via novel nuclear receptor translocation assays. Mean plasma Vtg was elevated (>0.2mg/ml) in male smallmouth bass at four sites and in male largemouth bass at one site. This is the first reconnaissance survey of this scope conducted on US National Wildlife Refuges. The baseline data collected here provide a necessary benchmark for future monitoring and justify more comprehensive NWR-specific studies.

[Diabetes and dementia]. / Diabetes und Demenz.

Diabetes mellitus is a known risk factor for cognitive dysfunction and dementia. Chronic hyperglycemia, genetic predisposition, arterial hypertension, hyperlipoproteinemia, micro- and macrovascular diseases, and depression play a major role in the development of cognitive dysfunction. Both pathophysiology of diabetes and dementia and the specifics of diabetes therapy in patients with dementia are presented in this review.

[French validation of the anger reactions and goals scale (RBC)]. / Validation française de l'échelle des réactions et des buts liés à la colère (RBC).

BACKGROUND: The study presents the French validation of a German scale (AERZ) [Diagnostica 49 (2003) 97-109, revised Eur J Pers (2009)] measuring anger regulation. The French validation (RBC scale) comprises two subscales measuring seven anger reactions and seven anger goals. Disentangling dimensions related to anger reactions and anger goals, respectively, is the main advantage of this scale. In addition to seven cognitive-behavioral anger reactions (i.e., venting, rumination, submission, feedback, distraction, humor and downplaying the incident's negative impact), the RBC scale also addresses the cognitive representations underlying anger reactions by exploring anger goals (i.e., enforcing personal standards, enforcing social standards, downregulating affect, avoiding conflicts, protecting one's reputation, weighing costs and gaining revenge). METHOD: The original scale was translated following the scientific guidelines and recommendations for cultural adaptation of instruments. The adapted French version was tested with a sample of students (n=184, 70.7% were females) from the University of Luxembourg (M=21.31, S.D.=1.93). Students filled in a questionnaire composed of the RBC scale, the SF-36 quality of life scale and the STAXI-II anger instrument. The RBC scale comprises 56 items; reactions are assessed on a 4 point Likert scale from "almost never" (1) to "always" (4), whereas goals are assessed on a 4 point Likert scale from "not at all" (1) to "completely" (4). RESULTS: Factor analysis revealed a seven-factor solution for the anger reactions subscale (that explained 63.13% of the common variance) and a six-factor solution for the anger goals subscale (that explained 57.45% of the common variance). The original factorial structure was examined in confirmatory factor analysis. For the anger reactions subscale, a good model fit was found, with chi(2)(329)=546.38, p<0.1, CFI=0.87, RMSEA=0.06. For the anger goals subscale, a satisfactory model fit was observed, with chi(2)(335)=658.52, p<0.1, CFI=0.78, RMSEA=0.07 revealing a six-factorial structure that differed from the original version in the combination of two dimensions ("downregulating affect" and "protecting one's reputation"). The RBC scale's internal consistencies were found satisfactory with Cronbach's alphas ranging from 0.60 to 0.83 for the various dimensions. Part-whole correlations ranged from r(it)=0.27 to 0.80. Gender differences showed that female participants used significantly more rumination strategies and emotional regulation, whereas male students demonstrated greater humor in anger situations. Significant correlations between RBC and STAXI-II confirmed the construct validity of the RBC scale. Criteria validity was analyzed using the predictive value of the RBC dimensions on the quality of life subscales of the SF-36. CONCLUSION: The present results support the validity, the reliability and the sensitivity of the 56 items scale on anger regulation and its use in psychological research. Although our findings need to be replicated and the test-retest validity is subject to future verification, the present validation of the RBC scale offers a multidimensional inventory for measuring anger reactions and anger goals. This inventory may be used, for example, as a diagnostic tool or for testing the effectiveness of anger management interventions.

Continuous glucose monitoring reveals associations of glucose levels with QT interval length.

BACKGROUND: QTc interval lengthening during hypoglycemia is discussed as a mechanism linked to sudden death in diabetes patients and the so-called "dead in bed syndrome." Previous research reported a high interindividual variability in the glucose-QTc association. The present study aimed at deriving parameters for direction and strength of the glucose-QTc association on the patient level using combined Holter electrocardiogram (ECG) and continuous glucose monitoring. METHODS: Twenty type 1 diabetes patients were studied: mean (SD, range) age, 43.6 (10.8, 22-65) years; gender male (n [%]), 10 (50.0%); mean (SD) hemoglobin A1C, 8.5% (1.0%); and impaired hypoglycemia awareness (n [%]), six (30.0%). Continuous interstitial glucose monitoring and Holter ECG monitoring were performed for 48 h. Hierarchical (mixed) regression modeling was used to account for the structure of the data. RESULTS: Glucose levels during nighttime were negatively associated with QTc interval length if the data structure was accounted for (b [SE] = -0.76 [0.17], P = 0.000). Exploratory regression analysis revealed hypoglycemia awareness as the only predictor of the individual strength of the glucose-QTc association, with the impaired awareness group showing less evidence for an association of low glucose with QTc lengthening. CONCLUSIONS: Mixed regression allows for deriving parameters for the glucose-QTc association on the patient level. Consistent with previous studies, we found a large interindividual variability in the glucose-QTc association. The finding on impaired hypoglycemia awareness patients has to be interpreted with caution but provides some support for the role of sympathetic activation for the QTc-glucose link.

Association of glucose levels and glucose variability with mood in type 1 diabetic patients.

AIMS/HYPOTHESIS: The aim of this study was to investigate the association of glucose levels and variability of glucose, assessed by continuous glucose monitoring, with mood in type 1 diabetic patients. MATERIALS AND METHODS: Thirty-six type 1 diabetic patients (77.8% male, age: 31.1 +/- 10.0 years; disease duration: 14.7 +/- 7.1 years, BMI: 26.7 +/- 5.1 kg/m2, HbA1c 8.4 +/-1.8%, 27.8% with continuous subcutaneous insulin infusion [CSII] therapy) used a continuous glucose monitoring system for 48.8 h. During this time the patients rated their current mood states 14.6 times on average, using the University of Wales Institute of Science and Technology Mood Adjective Checklist and hand-held computers. RESULTS: Sensor performance was satisfactory, with a mean absolute difference from reference laboratory glucose measurement of 13.7%. Current glucose values were significantly associated with ratings of 'tension' (z = 2.40), 'hedonic tone' (z = -2.63) and 'energetic arousal' (z = -2.09). 'Anger' (z = 1.64) was not significantly associated with glucose values. The glucose AUC during the 60 min prior to the mood rating showed similar associations. The two parameters of glucose variability-coefficient of variation and absolute glucose change during the 60 min prior to the mood ratings-did not show any significant association with the mood ratings. The magnitude of association was significantly higher for glucose level than for glucose variability in the scales 'tension' and 'hedonic tone'. CONCLUSIONS/INTERPRETATION: High glucose values had a negative impact on mood; positive mood ratings decreased, whereas negative mood ratings increased. The association between mood and glucose variability seemed to be less important than that between glucose level and mood.

The effect of an education programme (HyPOS) to treat hypoglycaemia problems in patients with type 1 diabetes.

BACKGROUND: In a randomized, prospective multi-centre trial, the effect of a specific training programme (HyPOS) for patients with hypoglycaemia problems was compared with a control group (CG), receiving a standardized education programme aiming at avoidance of hypoglycaemia by optimization of insulin therapy. METHODS: A total of 164 type 1 diabetes patients (age 46.0 +/- 12.5 yrs, HbA(1c) 7.3 +/- 1.0%, 50% male) were randomized. Hypoglycaemia awareness was measured by the hypoglycaemia awareness questionnaire (HAQ) and by a visual analogue scale (VAS). There were no baseline differences. RESULTS: After a 6-month follow-up, hypoglycaemia awareness significantly improved in HyPOS compared to that in the CG (Delta HAQ 0.7 [95% CL 0.1-1.2], p = 0.024, Delta VAS 0.8 [95% CL 0.2 - 1.2], p = 0.015). In HyPOS, the threshold for detection of low blood glucose (Delta 0.2 mmol/L [95% CL 0.03 - 0.04], p = 0.02) and the treatment of low blood glucose (Delta 4.6 g [95% CL 1.6 - 7.6], p = 0.03) increased significantly. The number of undetected hypogylcaemic episodes (Delta - 1.4 episodes per week [95% CL 0.4-2.5], p = 0.01) and the rate of mild hypoglycaemia dropped significantly in HyPOS (Delta 2.1% [95% CL 0.5-5.3], p = 0.015). The numbers of severe (Delta 0.3 events per patient per year [95% CL - 0.04-1.0], p = 0.037) and very severe hypoglycaemic episodes (Delta 0.3 events per patient per year [95% CL - 0.1-0.7], p = 0.09) were lower in HyPOS, but these differences were not significant. CONCLUSION: Compared to the CG, HyPOS demonstrates additional benefits in terms of improving impaired hypoglycaemia awareness, reducing mild hypoglycaemia, detecting low blood glucose, and treating low blood glucose.

Microdialysis-based 48-hour continuous glucose monitoring with GlucoDay: clinical performance and patients' acceptance.

BACKGROUND: This study was designed to assess clinical performance and patients' acceptance of the minimally invasive microdialysis-based continuous glucose monitoring system Gluco- Day() (Menarini Diagnostics, Florence, Italy) with a targeted monitoring time of 48 h. METHODS: An inpatient sample of 28 patients with diabetes was studied. The analysis of clinical performance was performed using mean absolute differences (MAD) (in percent), Pearson correlations, the Bland-Altman analysis, and Clarke Error Grid Analysis (EGA). GlucoDay glucose values were compared with laboratory standard blood glucose measurements (glucohexokinase assay). The patients' acceptance of the monitoring device was assessed via two self-report scales (pain during application and discomfort while wearing device). RESULTS: A mean (+/- SD) monitoring time of 45.7 +/- 3.3 h with a total of 484 paired readings could be achieved. A correlation of r (average) = 0.91 and a MAD of 19.9% indicated satisfactory to good clinical performance. Of the paired readings, 95.5% fell into the acceptable A and B zones of the EGA. Rather wide 95% limits of agreement were revealed in the Bland-Altman analysis. Whereas virtually no pain was experienced during sensor application, discomfort associated with wearing the device was rather high. All of the participants, however, stated that they would wear the device again. CONCLUSIONS: Satisfactory to good performance of the GlucoDay monitor was observed, indicating the device to be suitable for routine clinical use. In particular, however, the discomfort experienced during wearing requires further improvements in its usability.

How to screen for depression and emotional problems in patients with diabetes: comparison of screening characteristics of depression questionnaires, measurement of diabetes-specific emotional problems and standard clinical assessment.

AIMS/HYPOTHESIS: We compared the screening performance of different measures of depression: the standard clinical assessment (SCA); the Beck Depression Inventory (BDI); the Center of Epidemiological Studies-Depression Scale (CES-D); and the Problem Areas in Diabetes (PAID) questionnaire, which assesses diabetes-specific distress. We also studied the ability of these measures to detect diabetes-related distress. MATERIALS AND METHODS: A total of 376 diabetic patients (37.2% type 1; 23.9% type 2 without insulin treatment, 38.8% type 2 with insulin) completed the BDI and CES-D; patients who screened positive participated in a diagnostic interview, the Composite International Diagnostic Interview (CIDI). Also, all patients completed the PAID questionnaire. Results of the SCA that related to depression diagnosis were reviewed to correct for false negative screening results. RESULTS: The prevalence of clinical depression was 14.1%, with an additional 18.9% of patients receiving a diagnosis of subclinical depression. Sensitivity for clinical depression in SCA (56%) was moderate, whereas BDI, CES-D and the PAID questionnaire showed satisfactory sensitivity (87, 79 and 81%, respectively). For subclinical depression, the sensitivity of the PAID questionnaire (79%) was sufficient, whereas that of SCA (25%) was poor. All methods showed low sensitivity for the detection of diabetes-specific emotional problems (SCA 19%, CIDI 34%, BDI 60%, CES-D 49%). CONCLUSIONS/INTERPRETATION: The screening performance of SCA for clinical and subclinical depression was modest. Additional screening for depression using the PAID or another depression questionnaire seems reasonable. The ability of depression screening measures to identify diabetes-related distress is modest, suggesting that the PAID questionnaire could be useful when screening diabetic patients for both depression and emotional problems.

Affective and anxiety disorders in a German sample of diabetic patients: prevalence, comorbidity and risk factors.

AIMS: The aims of this study were to examine (1) the prevalence of clinical and subclinical anxiety and affective disorders in a sample of diabetic patients attending a secondary care clinic in Germany and (2) risk factors associated with the occurrence of these disorders. METHODS: Four hundred and twenty diabetic patients (36.9% Type 1; 24.7% Type 2; 38.4% Type 2 with insulin) participated in a questionnaire-based screening survey. Those who screened positive received a diagnostic interview. RESULTS: Prevalence of clinical affective disorders was 12.6%, with an additional 18.8% of patients reporting depressive symptoms without fulfilling all criteria for a clinical affective disorder. The prevalence of anxiety disorders was 5.9%, with an additional 19.3% of patients reporting some anxiety symptoms. The comorbidity rate of affective and anxiety disorders was 1.8%, whereas 21.4% of the diabetic patients reported elevated affective as well as anxiety symptomatology. Logistic regression established demographic variables such as age, female gender and living alone as well as diabetes-specific parameters such as insulin treatment in Type 2 diabetes, hypoglycaemia problems and poor glycaemic control as risk factors for affective disorders. For anxiety symptoms female gender, younger age and Type 2 diabetes were significant independent variables. CONCLUSION: The prevalence of affective disorders in diabetic patients was twofold higher than in the non-diabetic population, whereas prevalence for anxiety disorders was not increased. Analysis of risk factors can facilitate the identification of patients who are at a greater risk for these disorders.

Reversible cognitive deterioration after a single episode of severe hypoglycaemia: a case report.

A case of a male 34-year-old Type 1 diabetic patient who experienced a prolonged severe hypoglycaemic episode is presented. After the hypoglycaemic event, the patient suffered from moderate to severe neuropsychological impairments. On the basis of neuropsychological assessment results, diabetes therapy was modified (less complex insulin regimen, fixed insulin doses and fixed carbohydrate distribution). At a follow-up examination (3 months), presumable complete recovery of cognitive function was observed. This case demonstrates the possible detrimental neuropsychological effects of severe hypoglycaemia, that, in this case, turned out to be reversible. It highlights the clinical implications of impaired cognitive function on self-care and self-management abilities and the usefulness of neuropsychological testing in clinical diabetes care.

Assessment of hypoglycaemia awareness using continuous glucose monitoring.

AIMS: To investigate the possibility of assessing hypoglycaemia awareness in patients with Type 1 diabetes using continuous glucose monitoring. METHODS: Twenty patients with Type 1 diabetes were investigated. Ten patients with Type 1 diabetes and strongly impaired hypoglycaemia awareness were compared with 10 patients with intact hypoglycaemia awareness regarding quality of hypoglycaemia perception (number of undetected hypoglycaemic episodes per 24 h, glucose level < 3.3 mmol/l). Hypoglycaemia detection was assessed using the event function of the Continuous Glucose Monitoring System (CGMS; Medtronic MiniMed, Northridge, CA, USA). Patients were instructed to enter an event upon suspecting being hypoglycaemic. RESULTS: Satisfactory CGMS performance could be achieved [mean r = 0.893 between calibration measurements and CGMS data, mean absolute difference (MAD) = 20.6%], although artefacts were observable and had to be controlled. Hypoglycaemia unaware patients showed a significantly higher total number of hypoglycaemic episodes (P < 0.05), number of undetected hypoglycaemic episodes (P < 0.01), and mean glucose levels (P < 0.05). Even in aware patients, undetected hypoglycaemia was observable. No significant differences regarding occurrence of nocturnal hypoglycaemia were observable. CONCLUSIONS: The possibility of direct assessment of hypoglycaemia awareness using continuous glucose monitoring was demonstrated. Its application in clinical practice could be of use for assessing hypoglycaemia perception and evaluating the impact of treatment changes on hypoglycaemia awareness.

Emotional changes during experimentally induced hypoglycaemia in type 1 diabetes.

Emotional changes during experimentally induced hypoglycaemia in type 1 diabetic patients were investigated using a hyperinsulinaemic glucose clamp. In the experimental group (n=11), blood glucose was stabilised at euglycaemia (5.6 mmol/l, phase 1), then lowered to 2.5 mmol/l (phase 2) and raised to 5.6 mmol/l (phase 3). In the control group (n=11), euglycaemia was maintained during all phases. Hypoglycaemia elicited the expected endocrine, symptomatic and neuroglycopenic effects. During hypoglycaemia negative mood states increased significantly, whereas positive mood states decreased. Hypoglycaemia prolonged rating time of emotional stimuli (drawn from IAPS) significantly. The arousal ratings of the slides were higher during hypoglycaemia. Valence and dominance ratings were not affected. Epinephrine and norepinephrine release correlated with a higher arousal rating and a decrease in positive mood states. Deterioration in neuropsychological tasks correlated with an increase in negative mood states. Experimental induction of hypoglycaemia can offer a new research model to study emotional processes.

Type A allatostatins from Drosophila melanogaster and Diplotera puncata activate two Drosophila allatostatin receptors, DAR-1 and DAR-2, expressed in CHO cells.

The type-A allatostatins A (AST-A) are a group of insect peptides with a common C-terminal motif Y/FXFGL-NH(2). The existence of at least four putative type A Drosophila melanogaster ASTs (called type A drostatins or DST-As) has been predicted from the sequence of a recently cloned DST-A preprohormone [C. Lenz et al. (2000) Biochem. Biophys. Res. Commun. 273, 126-1131]. SRPYSFGL-NH(2), (DST-3A), the only DST isolated from Drosophila so far, activated the first cloned DST-A GPCR (DAR-1) [N. Birgül et al. (1999) EMBO J. 18, 5892-5900]. A newly cloned orphan Dm GPCR, which shares 47% overall and 60% transmembrane region sequence identity with DAR-1, was classified as a second putative Dm DST-A receptor (DAR-2) [C. Lenz et al. (2000) Biochem. Biophys. Res. Commun. 273, 571-577]. Although activation of DAR-2 by DSTs has been postulated, no experimental evidence for that has been presented to date. In this study, we expressed both DAR-1 and DAR-2 in CHO cells and used a GTPgammaS and a Ca(2+) mobilization assay for pharmacological evaluation of the receptors. Synthetically prepared DST-As, as well as selected Diplotera punctata (cockroach) ASTs, activated DAR-1 and DAR-2 in both functional assays indicating ligand redundancy and cross species activity. Cell pretreatment with pertussis toxin led to some differences in the nature and magnitude of signaling pathways at the DAR-1 and DAR-2 receptors, suggesting possible differential coupling to cellular effector system(s) and distinct biological functions of each receptor in vivo.

Pharmacology of FMRFamide-related peptides in helminths.

Nervous systems of helminths are highly peptidergic. Species in the phylum Nematoda (roundworms) possess at least 50 FMRFamide-related peptides (FaRPs), with more yet to be identified. To date, few non-FaRP neuropeptides have been identified in these organisms, though evidence suggests that other families are present. FaRPergic systems have important functions in nematode neuromuscular control. In contrast, species in the phylum Platyhelminthes (flatworms) apparently utilize fewer FaRPs than do nematodes; those species examined possess one or two FaRPs. Other neuropeptides, such as neuropeptide F (NPF), play key roles in flatworm physiology. Although progress has been made in the characterization of FaRP pharmacology in helminths, much remains to be learned. Most studies on nematodes have been done with Ascaris suum because of its large size. However, thanks to the Caenorhabditis elegans genome project, we know most about the FaRP complement of this free-living animal. That essentially all C. elegans FaRPs are active on at least one A. suum neuromuscular system argues for conservation of ligand-receptor recognition features among the Nematoda. Structure-activity studies on nematode FaRPs have revealed that structure-activity relationship (SAR) "rules" differ considerably among the FaRPs. Second messenger studies, along with experiments on ionic dependence and anatomical requirements for activity, reveal that FaRPs act through many different mechanisms. Platyhelminth FaRPs are myoexcitatory, and no evidence exists of multiple FaRP receptors in flatworms. Interestingly, there are examples of cross-phylum activity, with some nematode FaRPs being active on flatworm muscle. The extent to which other invertebrate FaRPs show cross-phylum activity remains to be determined. How FaRPergic nerves contribute to the control of behavior in helminths, and are integrated with non-neuropeptidergic systems, also remains to be elucidated.