Early Metabolic Endpoints Identify Persistent Treatment Efficacy in Recent-Onset Type 1 Diabetes Immunotherapy Trials

OBJECTIVE

Mixed-meal tolerance test-stimulated area under the curve (AUC) C-peptide at 12-24 months represents the primary end point for nearly all intervention trials seeking to preserve β-cell function in recent-onset type 1 diabetes. We hypothesized that participant benefit might be detected earlier and predict outcomes at 12 months posttherapy. Such findings would support shorter trials to establish initial efficacy.

RESEARCH DESIGN AND METHODS

We examined data from six Type 1 Diabetes TrialNet immunotherapy randomized controlled trials in a post hoc analysis and included additional stimulated metabolic indices beyond C-peptide AUC. We partitioned the analysis into successful and unsuccessful trials and analyzed the data both in the aggregate as well as individually for each trial.

RESULTS

Among trials meeting their primary end point, we identified a treatment effect at 3 and 6 months when using C-peptide AUC (P = 0.030 and P < 0.001, respectively) as a dynamic measure (i.e., change from baseline). Importantly, no such difference was seen in the unsuccessful trials. The use of C-peptide AUC as a 6-month dynamic measure not only detected treatment efficacy but also suggested long-term C-peptide preservation (R2 for 12-month C-peptide AUC adjusted for age and baseline value was 0.80, P < 0.001), and this finding supported the concept of smaller trial sizes down to 54 participants.

CONCLUSIONS

Early dynamic measures can identify a treatment effect among successful immune therapies in type 1 diabetes trials with good long-term prediction and practical sample size over a 6-month period. While external validation of these findings is required, strong rationale and data exist in support of shortening early-phase clinical trials.

Longitudinal Assessment of Pancreas Volume by MRI Predicts Progression to Stage 3 Type 1 Diabetes

OBJECTIVE

This multicenter prospective cohort study compared pancreas volume as assessed by MRI, metabolic scores derived from oral glucose tolerance testing (OGTT), and a combination of pancreas volume and metabolic scores for predicting progression to stage 3 type 1 diabetes (T1D) in individuals with multiple diabetes-related autoantibodies.

RESEARCH DESIGN AND METHODS

Pancreas MRI was performed in 65 multiple autoantibody-positive participants enrolled in the Type 1 Diabetes TrialNet Pathway to Prevention study. Prediction of progression to stage 3 T1D was assessed using pancreas volume index (PVI), OGTT-derived Index60 score and Diabetes Prevention Trial-Type 1 Risk Score (DPTRS), and a combination of PVI and DPTRS.

RESULTS

PVI, Index60, and DPTRS were all significantly different at study entry in 11 individuals who subsequently experienced progression to stage 3 T1D compared with 54 participants who did not experience progression (P < 0.005). PVI did not correlate with metabolic testing across individual study participants. PVI declined longitudinally in the 11 individuals diagnosed with stage 3 T1D, whereas Index60 and DPTRS increased. The area under the receiver operating characteristic curve for predicting progression to stage 3 from measurements at study entry was 0.76 for PVI, 0.79 for Index60, 0.79 for DPTRS, and 0.91 for PVI plus DPTRS.

CONCLUSIONS

These findings suggest that measures of pancreas volume and metabolism reflect distinct components of risk for developing stage 3 type 1 diabetes and that a combination of these measures may provide superior prediction than either alone.

Abatacept for Delay of Type 1 Diabetes Progression in Stage 1 Relatives at Risk: A Randomized, Double-Masked, Controlled Trial

OBJECTIVE

Previous studies showed that inhibiting lymphocyte costimulation reduces declining β-cell function in individuals newly diagnosed with type 1 diabetes. We tested whether abatacept would delay or prevent progression of type 1 diabetes from normal glucose tolerance (NGT) to abnormal glucose tolerance (AGT) or to diabetes and the effects of treatment on immune and metabolic responses.

RESEARCH DESIGN AND METHODS

We conducted a phase 2, randomized, placebo-controlled, double-masked trial of abatacept in antibody-positive participants with NGT who received monthly abatacept/placebo infusions for 12 months. The end point was AGT or diabetes, assessed by oral glucose tolerance tests.

RESULTS

A total of 101 participants received abatacept and 111 placebo. Of these, 81 (35 abatacept and 46 placebo) met the end point of AGT or type 1 diabetes diagnosis (hazard ratio 0.702; 95% CI 0.452, 1.09; P = 0.11) The C-peptide responses to oral glucose tolerance tests were higher in the abatacept arm (P < 0.03). Abatacept reduced the frequency of inducible T-cell costimulatory (ICOS)+ PD1+ T-follicular helper (Tfh) cells during treatment (P < 0.0001), increased naive CD4+ T cells, and also reduced the frequency of CD4+ regulatory T cells (Tregs) from the baseline (P = 0.0067). Twelve months after treatment, the frequency of ICOS+ Tfh, naive CD4+ T cells, and Tregs returned to baseline.

CONCLUSIONS

Although abatacept treatment for 1 year did not significantly delay progression to glucose intolerance in at-risk individuals, it impacted immune cell subsets and preserved insulin secretion, suggesting that costimulation blockade may modify progression of type 1 diabetes.

Barriers to Screening: An Analysis of Factors Impacting Screening for Type 1 Diabetes Prevention Trials

Context

Participants with stage 1 or 2 type 1 diabetes (T1D) qualify for prevention trials, but factors involved in screening for such trials are largely unknown.

Objective

To identify factors associated with screening for T1D prevention trials.

Methods

This study included TrialNet Pathway to Prevention participants who were eligible for a prevention trial: oral insulin (TN-07, TN-20), teplizumab (TN-10), abatacept (TN-18), and oral hydroxychloroquine (TN-22). Univariate and multivariate logistic regression models were used to examine participant, site, and study factors at the time of prevention trial accrual.

Results

Screening rates for trials were: 50% for TN-07 (584 screened/1172 eligible), 9% for TN-10 (106/1249), 24% for TN-18 (313/1285), 17% for TN-20 (113/667), and 28% for TN-22 (371/1336). Younger age and male sex were associated with higher screening rates for prevention trials overall and for oral therapies. Participants with an offspring with T1D showed lower rates of screening for all trials and oral drug trials compared with participants with other first-degree relatives as probands. Site factors, including larger monitoring volume and US site vs international site, were associated with higher prevention trial screening rates.

Conclusions

Clear differences exist between participants who screen for prevention trials and those who do not screen and between the research sites involved in prevention trial screening. Participant age, sex, and relationship to proband are significantly associated with prevention trial screening in addition to key site factors. Identifying these factors can facilitate strategic recruitment planning to support rapid and successful enrollment into prevention trials.

IL-6 receptor blockade does not slow β cell loss in new-onset type 1 diabetes

BackgroundIL-6 receptor (IL-6R) signaling drives development of T cell populations important to type 1 diabetes pathogenesis. We evaluated whether blockade of IL-6R with monoclonal antibody tocilizumab would slow loss of residual β cell function in newly diagnosed type 1 diabetes patients.MethodsWe conducted a multicenter, randomized, placebo-controlled, double-blind trial with tocilizumab in new-onset type 1 diabetes. Participants were screened within 100 days of diagnosis. Eligible participants were randomized 2:1 to receive 7 monthly doses of tocilizumab or placebo. The primary outcome was the change from screening in the mean AUC of C-peptide collected during the first 2 hours of a mixed meal tolerance test at week 52 in pediatric participants (ages 6-17 years).ResultsThere was no statistical difference in the primary outcome between tocilizumab and placebo. Immunophenotyping showed reductions in downstream signaling of the IL-6R in T cells but no changes in CD4 memory subsets, Th17 cells, Tregs, or CD4+ T effector cell resistance to Treg suppression. A DC subset decreased during therapy but regressed to baseline once therapy stopped. Tocilizumab was well tolerated.ConclusionTocilizumab reduced T cell IL-6R signaling but did not modulate CD4+ T cell phenotypes or slow loss of residual β cell function in newly diagnosed individuals with type 1 diabetes.Trial RegistrationClinicalTrials.gov NCT02293837.FundingNIH National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK) and National Institute of Allergy and Infectious Diseases (NIAID) UM1AI109565, UL1TR000004 from NIH/National Center for Research Resources (NCRR) Clinical and Translational Science Award (CTSA), NIH/NIDDK P30DK036836, NIH/NIDDK U01DK103266, NIH/NIDDK U01DK103266, 1UL1TR000064 from NIH/NCRR CTSA, NIH/National Center for Advancing Translational Sciences (NCATS) UL1TR001878, UL1TR002537 from NIH/CTSA; National Health and Medical Research Council Practitioner Fellowship (APP1136735), NIH/NIDDK U01-DK085476, NIH/CTSA UL1-TR002494, Indiana Clinical and Translational Science Institute Award UL1TR002529, Vanderbilt Institute for Clinical and Translational Research UL1TR000445. NIH/NCATS UL1TR003142, NIH/CTSA program UL1-TR002494, Veteran Affairs Administration, and 1R01AI132774.

Randomized Trial of a Positive Psychology Intervention for Adolescents With Type 1 Diabetes

OBJECTIVE

To evaluate the effects of a positive psychology intervention for adolescents with type 1 diabetes (T1D) on adherence, glycemic control, and quality of life.

METHODS

Adolescents with T1D (n = 120) and their caregivers were randomized to either an Education (EDU) (n = 60) or Positive Affect (PA) intervention (n = 60). Adolescents in the PA group received the intervention reminders (gratitude, self-affirmation, parental affirmation, and small gifts) via text messages or phone calls over 8 weeks. Questionnaires were completed by adolescents and caregivers and clinical data (glucometer and HbA1c) were collected at baseline 3 and 6 months. Data were analyzed using generalized linear modeling.

RESULTS

After adjusting for covariates, adolescents in the PA group demonstrated significant improvement in quality of life at 3 months, compared to the EDU group, but this was not sustained at 6 months. Similarly, the PA group showed a significant decrease in disengagement coping at 3 months but not at 6 months. There was no significant intervention effect on blood glucose monitoring, but the odds of clinically significantly improvement (checking at least one more time/day) were about twice as high in the PA group as the EDU group. No significant effects were found for glycemic control.

CONCLUSIONS

A positive psychology intervention had initial significant, positive effects on coping and quality of life in adolescents with T1D. A more intensive or longer-lasting intervention may be needed to sustain these effects and to improve adherence and glycemic control.

The risk of progression to type 1 diabetes is highly variable in individuals with multiple autoantibodies following screening

AIMS/HYPOTHESIS

Young children who develop multiple autoantibodies (mAbs) are at very high risk for type 1 diabetes. We assessed whether a population with mAbs detected by screening is also at very high risk, and how risk varies according to age, type of autoantibodies and metabolic status.

METHODS

Type 1 Diabetes TrialNet Pathway to Prevention participants with mAbs (n = 1815; age, 12.35 ± 9.39 years; range, 1-49 years) were analysed. Type 1 diabetes risk was assessed according to age, autoantibody type/number (insulin autoantibodies [IAA], glutamic acid decarboxylase autoantibodies [GADA], insulinoma-associated antigen-2 autoantibodies [IA-2A] or zinc transporter 8 autoantibodies [ZnT8A]) and Index60 (composite measure of fasting C-peptide, 60 min glucose and 60 min C-peptide). Cox regression and cumulative incidence curves were utilised in this cohort study.

RESULTS

Age was inversely related to type 1 diabetes risk in those with mAbs (HR 0.97 [95% CI 0.96, 0.99]). Among participants with 2 autoantibodies, those with GADA had less risk (HR 0.35 [95% CI 0.22, 0.57]) and those with IA-2A had higher risk (HR 2.82 [95% CI 1.76, 4.51]) of type 1 diabetes. Those with IAA and GADA had only a 17% 5 year risk of type 1 diabetes. The risk was significantly lower for those with Index60 <1.0 (HR 0.23 [95% CI 0.19, 0.30]) vs those with Index60 values ≥1.0. Among the 12% (225/1815) ≥12.0 years of age with GADA positivity, IA-2A negativity and Index60 <1.0, the 5 year risk of type 1 diabetes was 8%.

CONCLUSIONS/INTERPRETATION

Type 1 diabetes risk varies substantially according to age, autoantibody type and metabolic status in individuals screened for mAbs. An appreciable proportion of older children and adults with mAbs appear to have a low risk of progressing to type 1 diabetes at 5 years. With this knowledge, clinical trials of type 1 diabetes prevention can better target those most likely to progress.

Correlating maternal iodine status with neonatal thyroid function in two hospital populations in Ghana: a multicenter cross-sectional pilot study

Background

Congenital hypothyroidism is a common, yet easily treatable cause of poor growth and intellectual disability. Newborn screening programs play an important role in the early detection and treatment of congenital hypothyroidism. However, an estimated 71% of children are born in countries such as Ghana, which does not have a screening program. Iodine deficiency, a common cause of congenital hypothyroidism, is present in the Ghanaian population. Mild to moderate maternal iodine deficiency may negatively impact cognitive function in children. A structured approach to examine the association between maternal iodine levels and infant thyroid function may have important ramifications on our understanding of congenital hypothyroidism in Ghana. We investigated the hypothesis that maternal iodine deficiency impacts infant thyroid function, using Thyroid Stimulating Hormone (TSH) as a marker of thyroid function. We also explored potential opportunities and barriers to newborn screening for congenital hypothyroidism in Ghana.

Methods

This was a cross-sectional, multicenter pilot study of 250 women and their neonates recruited from post-natal clinics in Accra and Tamale, Ghana. We compared maternal urine iodine concentration and infant TSH, as well as maternal sociodemographic and nutrition information. Regression models were used to model the relationship between variables.

Results

Median infant TSH was 4.7 μIU/ml (95% CI: 3.9–5.5) in Accra. In Tamale, the median infant TSH was 3.5 μIU/ml (95%CI: 3.3 to 3.6) (Δ: 1.3 μIU/ml, 95% CI: 0.5–2.1, p = 0.002). Median maternal urine iodine concentrations were 141.0 μg/L (95% CI: 115.7 to 166.3) and 142.5 μg/L (95% CI: 125.1 to 160.0) in Accra and Tamale, respectively (Δ: − 1.5 μIU/ml, 95% CI: − 32.2 – 29.2, p = 0.925). There was a weakly positive correlation between maternal urine iodine and infant TSH (rho 0.1, p = 0.02). Almost one-third (30%) of women in both locations had biochemical evidence of iodine deficiency. Mothers with any formal education were more likely to have higher iodine levels than their counterparts who had no formal education (coefficient 0.31, p = 0.006).

Conclusions

Maternal iodine deficiency is prevalent in Ghana and is correlated to infant thyroid function. We recommend studies with larger sample sizes to assess the true scope of this relationship.

An Anti-CD3 Antibody, Teplizumab, in Relatives at Risk for Type 1 Diabetes

BACKGROUND

Type 1 diabetes is a chronic autoimmune disease that leads to destruction of insulin-producing beta cells and dependence on exogenous insulin for survival. Some interventions have delayed the loss of insulin production in patients with type 1 diabetes, but interventions that might affect clinical progression before diagnosis are needed.

METHODS

We conducted a phase 2, randomized, placebo-controlled, double-blind trial of teplizumab (an Fc receptor-nonbinding anti-CD3 monoclonal antibody) involving relatives of patients with type 1 diabetes who did not have diabetes but were at high risk for development of clinical disease. Patients were randomly assigned to a single 14-day course of teplizumab or placebo, and follow-up for progression to clinical type 1 diabetes was performed with the use of oral glucose-tolerance tests at 6-month intervals.

RESULTS

A total of 76 participants (55 [72%] of whom were ≤18 years of age) underwent randomization - 44 to the teplizumab group and 32 to the placebo group. The median time to the diagnosis of type 1 diabetes was 48.4 months in the teplizumab group and 24.4 months in the placebo group; the disease was diagnosed in 19 (43%) of the participants who received teplizumab and in 23 (72%) of those who received placebo. The hazard ratio for the diagnosis of type 1 diabetes (teplizumab vs. placebo) was 0.41 (95% confidence interval, 0.22 to 0.78; P = 0.006 by adjusted Cox proportional-hazards model). The annualized rates of diagnosis of diabetes were 14.9% per year in the teplizumab group and 35.9% per year in the placebo group. There were expected adverse events of rash and transient lymphopenia. KLRG1+TIGIT+CD8+ T cells were more common in the teplizumab group than in the placebo group. Among the participants who were HLA-DR3-negative, HLA-DR4-positive, or anti-zinc transporter 8 antibody-negative, fewer participants in the teplizumab group than in the placebo group had diabetes diagnosed.

CONCLUSIONS

Teplizumab delayed progression to clinical type 1 diabetes in high-risk participants. (Funded by the National Institutes of Health and others; ClinicalTrials.gov number, NCT01030861.).

Low-Dose Anti-Thymocyte Globulin Preserves C-Peptide, Reduces HbA1c, and Increases Regulatory to Conventional T-Cell Ratios in New-Onset Type 1 Diabetes: Two-Year Clinical Trial Data

A three-arm, randomized, double-masked, placebo-controlled phase 2b trial performed by the Type 1 Diabetes TrialNet Study Group previously demonstrated that low-dose anti-thymocyte globulin (ATG) (2.5 mg/kg) preserved β-cell function and reduced HbA_1c for 1 year in new-onset type 1 diabetes. Subjects (N = 89) were randomized to 1) ATG and pegylated granulocyte colony-stimulating factor (GCSF), 2) ATG alone, or 3) placebo. Herein, we report 2-year area under the curve (AUC) C-peptide and HbA_1c, prespecified secondary end points, and potential immunologic correlates. The 2-year mean mixed-meal tolerance test-stimulated AUC C-peptide, analyzed by ANCOVA adjusting for baseline C-peptide, age, and sex (n = 82) with significance defined as one-sided P < 0.025, was significantly higher in subjects treated with ATG versus placebo (P = 0.00005) but not ATG/GCSF versus placebo (P = 0.032). HbA_1c was significantly reduced at 2 years in subjects treated with ATG (P = 0.011) and ATG/GCSF (P = 0.022) versus placebo. Flow cytometry analyses demonstrated reduced circulating CD4:CD8 ratio, increased regulatory T-cell:conventional CD4 T-cell ratios, and increased PD-1⁺CD4⁺ T cells following low-dose ATG and ATG/GCSF. Low-dose ATG partially preserved β-cell function and reduced HbA_1c 2 years after therapy in new-onset type 1 diabetes. Future studies should determine whether low-dose ATG might prevent or delay the onset of type 1 diabetes.

Identical and Nonidentical Twins: Risk and Factors Involved in Development of Islet Autoimmunity and Type 1 Diabetes

OBJECTIVE

There are variable reports of risk of concordance for progression to islet autoantibodies and type 1 diabetes in identical twins after one twin is diagnosed. We examined development of positive autoantibodies and type 1 diabetes and the effects of genetic factors and common environment on autoantibody positivity in identical twins, nonidentical twins, and full siblings.

RESEARCH DESIGN AND METHODS

Subjects from the TrialNet Pathway to Prevention Study (N = 48,026) were screened from 2004 to 2015 for islet autoantibodies (GAD antibody [GADA], insulinoma-associated antigen 2 [IA-2A], and autoantibodies against insulin [IAA]). Of these subjects, 17,226 (157 identical twins, 283 nonidentical twins, and 16,786 full siblings) were followed for autoantibody positivity or type 1 diabetes for a median of 2.1 years.

RESULTS

At screening, identical twins were more likely to have positive GADA, IA-2A, and IAA than nonidentical twins or full siblings (all P < 0.0001). Younger age, male sex, and genetic factors were significant factors for expression of IA-2A, IAA, one or more positive autoantibodies, and two or more positive autoantibodies (all P ≤ 0.03). Initially autoantibody-positive identical twins had a 69% risk of diabetes by 3 years compared with 1.5% for initially autoantibody-negative identical twins. In nonidentical twins, type 1 diabetes risk by 3 years was 72% for initially multiple autoantibody-positive, 13% for single autoantibody-positive, and 0% for initially autoantibody-negative nonidentical twins. Full siblings had a 3-year type 1 diabetes risk of 47% for multiple autoantibody-positive, 12% for single autoantibody-positive, and 0.5% for initially autoantibody-negative subjects.

CONCLUSIONS

Risk of type 1 diabetes at 3 years is high for initially multiple and single autoantibody-positive identical twins and multiple autoantibody-positive nonidentical twins. Genetic predisposition, age, and male sex are significant risk factors for development of positive autoantibodies in twins.

Pancreas Volume Declines During the First Year After Diagnosis of Type 1 Diabetes and Exhibits Altered Diffusion at Disease Onset

OBJECTIVE

This study investigated the temporal dynamics of pancreas volume and microstructure in children and adolescents with recent-onset type 1 diabetes (T1D) and individuals without diabetes, including a subset expressing autoantibodies associated with the early stages of T1D.

RESEARCH DESIGN AND METHODS

MRI was performed in individuals with recent-onset stage 3 T1D (n = 51; median age 13 years) within 100 days after diagnosis (mean 67 days), 6 months, and 1 year postdiagnosis. Longitudinal MRI measurements were also made in similarly aged control participants (n = 57) and in autoantibody-positive individuals without diabetes (n = 20). The MRI protocol consisted of anatomical imaging to determine pancreas volume and quantitative MRI protocols interrogating tissue microstructure and composition.

RESULTS

Within 100 days of diabetes onset, individuals with T1D had a smaller pancreas (median volume 28.6 mL) than control participants (median volume 48.4 mL; P < 0.001), including when normalized by individual weight (P < 0.001). Longitudinal measurements of pancreas volume increased in control participants over the year, consistent with adolescent growth, but pancreas volume declined over the first year after T1D diagnosis (P < 0.001). In multiple autoantibody-positive individuals, the pancreas volume was significantly larger than that of the T1D cohort (P = 0.017) but smaller than that of the control cohort (P = 0.04). Diffusion-weighted MRI showed that individuals with recent-onset T1D had a higher apparent diffusion coefficient (P = 0.012), suggesting a loss of cellular structural integrity, with heterogeneous pancreatic distribution.

CONCLUSIONS

These results indicate that pancreas volume is decreased in stages 1, 2, and 3 of T1D and decreases during the first year after diabetes onset and that this loss of pancreatic volume is accompanied by microstructural changes.

A Type 1 Diabetes Genetic Risk Score Predicts Progression of Islet Autoimmunity and Development of Type 1 Diabetes in Individuals at Risk

OBJECTIVE

We tested the ability of a type 1 diabetes (T1D) genetic risk score (GRS) to predict progression of islet autoimmunity and T1D in at-risk individuals.

RESEARCH DESIGN AND METHODS

We studied the 1,244 TrialNet Pathway to Prevention study participants (T1D patients' relatives without diabetes and with one or more positive autoantibodies) who were genotyped with Illumina ImmunoChip (median [range] age at initial autoantibody determination 11.1 years [1.2-51.8], 48% male, 80.5% non-Hispanic white, median follow-up 5.4 years). Of 291 participants with a single positive autoantibody at screening, 157 converted to multiple autoantibody positivity and 55 developed diabetes. Of 953 participants with multiple positive autoantibodies at screening, 419 developed diabetes. We calculated the T1D GRS from 30 T1D-associated single nucleotide polymorphisms. We used multivariable Cox regression models, time-dependent receiver operating characteristic curves, and area under the curve (AUC) measures to evaluate prognostic utility of T1D GRS, age, sex, Diabetes Prevention Trial-Type 1 (DPT-1) Risk Score, positive autoantibody number or type, HLA DR3/DR4-DQ8 status, and race/ethnicity. We used recursive partitioning analyses to identify cut points in continuous variables.

RESULTS

Higher T1D GRS significantly increased the rate of progression to T1D adjusting for DPT-1 Risk Score, age, number of positive autoantibodies, sex, and ethnicity (hazard ratio [HR] 1.29 for a 0.05 increase, 95% CI 1.06-1.6; P = 0.011). Progression to T1D was best predicted by a combined model with GRS, number of positive autoantibodies, DPT-1 Risk Score, and age (7-year time-integrated AUC = 0.79, 5-year AUC = 0.73). Higher GRS was significantly associated with increased progression rate from single to multiple positive autoantibodies after adjusting for age, autoantibody type, ethnicity, and sex (HR 2.27 for GRS >0.295, 95% CI 1.47-3.51; P = 0.0002).

CONCLUSIONS

The T1D GRS independently predicts progression to T1D and improves prediction along T1D stages in autoantibody-positive relatives.

Individual Differences in Sensitivity to Interaural Differences in Time and Level

Previous research had indicated the existence of two groups—people more sensitive to interaural time differences than to interaural level (intensity) differences and people more sensitive to level differences than to time differences. A population of undergraduates was surveyed in an attempt to estimate the relative proportions of people in the two groups. Two characteristics possessed by previous Ss classified as time-sensitive or level-sensitive were used as the basis for classification of the present Ss. The psychophysical method was single-interval forced-choice, and Ss' task was to lateralize an auditory image. Usable data were obtained from 73 out of 76 Ss. Of those that met the criterion for classification into one of the two groups, about 25% were more sensitive to time differences than to level differences.

Hepatocyte ERBB3 and EGFR are required for maximal CCl4-induced liver fibrosis

Epidermal growth factor receptor (EGFR) and its ligands have been implicated in liver fibrosis. However, it has not been directly shown that hepatocellular genetic ablation of either this receptor tyrosine kinase or ERBB3, its interactive signaling partner, affects hepatic fibrosis. Carbon tetrachloride (CCl₄)-induced liver fibrosis in hepatocyte-specific (HS) mouse models of EGFR and ERBB3 ablation was evaluated in both single gene knockouts and an HS-EGFR-ERBB3 double knockout (DKO). Loss of hepatocellular EGFR or ERBB3 did not impact cytochrome P450-2E1 expression, the extent of centrilobular injury, or the initial regenerative response, but it did diminish liver fibrosis induced by chronic intraperitoneal administration of CCl₄ The reduction of liver fibrosis correlated with reduced α-smooth muscle actin expression. Maximal impact to fibrogenesis occurred in the ERBB3 and EGFR-ERBB3 DKO models, suggesting that EGFR-ERBB3 heterodimeric signaling in damaged hepatocytes may play a more important role in liver fibrosis than EGFR-EGFR homodimeric signaling. Immunohistochemical analyses of phospho-EGFR and phospho-ERBB3 isoforms revealed clear staining in hepatocytes, activated stellate cells, and macrophages. Our results support a role for the hepatocellular ERBB tyrosine kinases in fibrogenesis and suggest that pharmacologic inhibition of EGFR-ERBB3 signaling may reverse or retard hepatic fibrosis.

Loss of hepatocyte ERBB3 but not EGFR impairs hepatocarcinogenesis

Epidermal growth factor receptor (EGFR) and ERBB3 have been implicated in hepatocellular carcinogenesis (HCC). However, it is not known whether altering the activity of either EGFR or ERBB3 affects HCC development. We now show that Egfr(Dsk5) mutant mice, which have a gain-of-function allele that increases basal EGFR kinase activity, develop spontaneous HCC by 10 mo of age. Their tumors show increased activation of EGFR, ERBB2, and ERBB3 as well as AKT and ERK1,2. Hepatocyte-specific models of EGFR and ERBB3 gene ablation were generated to evaluate how the loss of these genes affected tumor progression. Loss of either receptor tyrosine kinase did not alter liver development or regenerative liver growth following carbon tetrachloride injection. However, using a well-characterized model of HCC in which N-nitrosodiethylamine is injected into 14-day-old mice, we discovered that loss of hepatocellular ERBB3 but not EGFR, which occurred after tumor initiation, retarded liver tumor formation and cell proliferation. We found no evidence that this was due to increased apoptosis or diminished phosphatidylinositol-3-kinase activity in the ERBB3-null cells. However, the relative amount of phospho-STAT3 was diminished in tumors derived from these mice, suggesting that ERBB3 may promote HCC through STAT3 activation.

A review of adolescent adherence in type 1 diabetes and the untapped potential of diabetes providers to improve outcomes

Only 21 % of adolescents with type 1 diabetes (T1D) meet glycemic goals set forth by the American Diabetes Association. Adherence to therapy is a particular concern in this population, and the association between poor adherence and worsening glycemic control indicates that there is a critical need to improve adherence to therapy in adolescents with T1D. In this article, we review barriers to adherence in adolescents with T1D and discuss interventions aimed at improving adherence to therapy and glycemic control. Interventions include technology-based applications, family-based therapies, motivational interviewing, and others. Notably, less than 10 % of the interventions reviewed are provider-led, clinic-based interventions, and few have focused on regimen-related aspects of adherence. This article also outlines the importance of provider communication and the role of providers in facilitating adherence behaviors in adolescents with T1D. Finally, we suggest future directions of research to improve adherence to therapy in adolescents with T1D.

Loss of hepatocyte EGFR has no effect alone but exacerbates carbon tetrachloride-induced liver injury and impairs regeneration in hepatocyte Met-deficient mice

The role(s) of the epidermal growth factor receptor (EGFR) in hepatocytes is unknown. We generated a murine hepatocyte specific-EGFR knockout (KO) model to evaluate how loss of hepatocellular EGFR expression affects processes such as EGF clearance, circulating EGF concentrations, and liver regeneration following 70% resection or CCl4-induced centrilobular injury. We were able to disrupt EGFR expression effectively in hepatocytes and showed that the ability of EGF and heregulin (HRG) to phosphorylate EGFR and ERBB3, respectively, required EGFR. Loss of hepatocellular EGFR impaired clearance of exogenous EGF from the portal circulation but paradoxically resulted in reduced circulating levels of endogenous EGF. This was associated with decreased submandibular salivary gland production of EGF. EGFR disruption did not result in increased expression of other ERBB proteins or Met, except in neonatal mice. Liver regeneration following 70% hepatectomy revealed a mild phenotype, with no change in cyclin D1 expression and slight differences in cyclin A expression compared with controls. Peak 5-bromo-2'-deoxyuridine labeling was shifted from 36 to 48 h. Centrilobular damage and regenerative response induced by carbon tetrachloride (CCl4) were identical in the KO and wild-type mice. In contrast, loss of Met increased CCl4-induced necrosis and delayed regeneration. Although loss of hepatocellular EGFR alone did not have an effect in this model, EGFR-Met double KOs displayed enhanced necrosis and delayed liver regeneration compared with Met KOs alone. This suggests that EGFR and Met may partially compensate for the loss of the other, although other compensatory mechanisms can be envisioned.

Development and validation of the diabetes adolescent problem solving questionnaire

OBJECTIVE

Problem solving is a critical diabetes self-management skill. Because of a lack of clinically feasible measures, our aim was to develop and validate a self-report self-management problem solving questionnaire for adolescents with type 1 diabetes (T1D).

METHODS

A multidisciplinary team of diabetes experts generated questionnaire items that addressed diabetes self-management problem solving. Iterative feedback from parents and adolescents resulted in 27 items. Adolescents from two studies (N=156) aged 13-17 were recruited through a pediatric diabetes clinic and completed measures through an online survey. Glycemic control was measured by HbA1c recorded in the medical record.

RESULTS

Empirical elimination of items using principal components analyses resulted in a 13-item unidimensional measure, the diabetes adolescent problem solving questionnaire (DAPSQ) that explained 56% of the variance. The DAPSQ demonstrated internal consistency (Cronbach's alpha=0.92) and was correlated with diabetes self-management (r=0.53, p<.001), self-efficacy (r=0.54, p<.001), and glycemic control (r=-0.24, p<.01).

CONCLUSION

The DAPSQ is a brief instrument for assessment of diabetes self-management problem solving in youth with T1D and is associated with better self-management behaviors and glycemic control.

PRACTICE IMPLICATIONS

The DAPSQ is a clinically feasible self-report measure that can provide valuable information regarding level of self-management problem solving and guide patient education.

Costimulation modulation with abatacept in patients with recent-onset type 1 diabetes: follow-up 1 year after cessation of treatment

OBJECTIVE We previously reported that 2 years of costimulation modulation with abatacept slowed decline of β-cell function in recent-onset type 1 diabetes (T1D). Subsequently, abatacept was discontinued and subjects were followed to determine whether there was persistence of effect. RESEARCH DESIGN AND METHODS Of 112 subjects (ages 6-36 years) with T1D, 77 received abatacept and 35 received placebo infusions intravenously for 27 infusions over 2 years. The primary outcome-baseline-adjusted geometric mean 2-h area under the curve (AUC) serum C-peptide during a mixed-meal tolerance test (MMTT) at 2 years-showed higher C-peptide with abatacept versus placebo. Subjects were followed an additional year, off treatment, with MMTTs performed at 30 and 36 months. RESULTS C-peptide AUC means, adjusted for age and baseline C-peptide, at 36 months were 0.217 nmol/L (95% CI 0.168-0.268) and 0.141 nmol/L (95% CI 0.071-0.215) for abatacept and placebo groups, respectively (P = 0.046). The C-peptide decline from baseline remained parallel with an estimated 9.5 months' delay with abatacept. Moreover, HbA1c levels remained lower in the abatacept group than in the placebo group. The slightly lower (nonsignificant) mean total insulin dose among the abatacept group reported at 2 years was the same as the placebo group by 3 years. CONCLUSIONS Costimulation modulation with abatacept slowed decline of β-cell function and improved HbA1c in recent-onset T1D. The beneficial effect was sustained for at least 1 year after cessation of abatacept infusions or 3 years from T1D diagnosis.

Epidermal growth factor receptor plays a role in the regulation of liver and plasma lipid levels in adult male mice

Dsk5 mice have a gain of function in the epidermal growth factor receptor (EGFR), caused by a point mutation in the kinase domain. We analyzed the effect of this mutation on liver size, histology, and composition. We found that the livers of 12-wk-old male Dsk5 heterozygotes (+/Dsk5) were 62% heavier compared with those of wild-type controls (+/+). The livers of the +/Dsk5 mice compared with +/+ mice had larger hepatocytes with prominent, polyploid nuclei and showed modestly increased cell proliferation indices in both hepatocytes and nonparenchymal cells. An analysis of total protein, DNA, and RNA (expressed relative to liver weight) revealed no differences between the mutant and wild-type mice. However, the livers of the +/Dsk5 mice had more cholesterol but less phospholipid and fatty acid. Circulating cholesterol levels were twice as high in adult male +/Dsk5 mice but not in postweaned young male or female mice. The elevated total plasma cholesterol resulted mainly from an increase in low-density lipoprotein (LDL). The +/Dsk5 adult mouse liver expressed markedly reduced protein levels of LDL receptor, no change in proprotein convertase subtilisin/kexin type 9, and a markedly increased fatty acid synthase and 3-hydroxy-3-methyl-glutaryl-CoA reductase. Increased expression of transcription factors associated with enhanced cholesterol synthesis was also observed. Together, these findings suggest that the EGFR may play a regulatory role in hepatocyte proliferation and lipid metabolism in adult male mice, explaining why elevated levels of EGF or EGF-like peptides have been positively correlated to increased cholesterol levels in human studies.

Targeting of memory T cells with alefacept in new-onset type 1 diabetes (T1DAL study): 12 month results of a randomised, double-blind, placebo-controlled phase 2 trial

BACKGROUND

Type 1 diabetes results from autoimmune targeting of the pancreatic β cells, likely mediated by effector memory T (Tem) cells. CD2, a T cell surface protein highly expressed on Tem cells, is targeted by the fusion protein alefacept, depleting Tem cells and central memory T (Tcm) cells. We postulated that alefacept would arrest autoimmunity and preserve residual β cells in patients newly diagnosed with type 1 diabetes.

METHODS

The T1DAL study is a phase 2, double-blind, placebo-controlled trial in patients with type 1 diabetes, aged 12-35 years who, within 100 days of diagnosis, were enrolled at 14 US sites. Patients were randomly assigned (2:1) to receive alefacept (two 12-week courses of 15 mg intramuscularly per week, separated by a 12-week pause) or a placebo. Randomisation was stratified by site, and was computer-generated with permuted blocks of three patients per block. All participants and site personnel were masked to treatment assignment. The primary endpoint was the change from baseline in mean 2 h C-peptide area under the curve (AUC) at 12 months. Secondary endpoints at 12 months were the change from baseline in the 4 h C-peptide AUC, insulin use, major hypoglycaemic events, and HbA1c concentrations. This trial is registered with ClinicalTrials.gov, number NCT00965458.

FINDINGS

Of 73 patients assessed for eligibility, 33 were randomly assigned to receive alefacept and 16 to receive placebo. The mean 2 h C-peptide AUC at 12 months increased by 0.015 nmol/L (95% CI -0.080 to 0.110) in the alefacept group and decreased by 0.115 nmol/L (-0.278 to 0.047) in the placebo group, and the difference between groups was not significant (p=0.065). However, key secondary endpoints were met: the mean 4 h C-peptide AUC was significantly higher (mean increase of 0.015 nmol/L [95% CI -0.076 to 0.106] vs decrease of -0.156 nmol/L [-0.305 to -0.006]; p=0.019), and daily insulin use (0.48 units per kg per day for placebo vs 0.36 units per kg per day for alefacept; p=0.02) and the rate of hypoglycaemic events (mean of 10.9 events per person per year for alefacept vs 17.3 events for placebo; p<0.0001) was significantly lower at 12 months in the alefacept group than in the placebo group. Mean HbA1c concentrations at week 52 were not different between treatment groups (p=0.75). So far, no serious adverse events were reported and all patients had at least one adverse event. In the alefacept group, 29 (88%) participants had an adverse event related to study drug versus 15 (94%) participants in the placebo group. In the alefacept group, 14 (42%) participants had grade 3 or 4 adverse events compared with nine (56%) participants in the placebo group; no deaths occurred.

INTERPRETATION

Although the primary outcome was not met, at 12 months, alefacept preserved the 4 h C-peptide AUC, lowered insulin use, and reduced hypoglycaemic events, suggesting efficacy. Safety and tolerability were similar in the alefacept and placebo groups. Alefacept could be useful to preserve β-cell function in patients with new-onset type 1 diabetes.

Factors that influence parental attitudes toward enrollment in type 1 diabetes trials

Aims

To assess parental attitudes towards type 1 diabetes clinical trials (T1DCTs) and factors that impact willingness to enroll their children with and without diabetes.

Methods

A cross-sectional survey of parents of children with type 1 diabetes was administered at an academic clinic and a diabetes educational event.

Results

Survey response rate was 36%. Of 166 participating parents, 76% were aware of T1DCTs. More parents reported willingness to enroll children with diabetes (47%) than unaffected children (36%). Only 18% recalled being asked to enroll their children, and of these, 60% agreed to enroll at least some of those times. Less than 30% were comfortable with placebos. Factors predicting willingness to enroll children with diabetes included healthcare provider trust, comfort with consent by proxy, low fear of child being a “guinea pig,” and comfort with placebo. Factors predicting willingness to enroll unaffected children were provider trust, comfort with consent by proxy, comfort with placebo, and perceived ease of understanding T1DCT information.

Conclusions

Parents report moderate willingness to enroll children in T1DCTs. Willingness is diminished by common trial methodologies. Although most parents recalled receiving trial-related information, significantly fewer recalled being asked to participate. Efforts to optimize effective communication around identified areas of parental concern may increase T1DCT participation.

Co-stimulation modulation with abatacept in patients with recent-onset type 1 diabetes: a randomised, double-blind, placebo-controlled trial

BACKGROUND

The immunopathogenesis of type 1 diabetes mellitus is associated with T-cell autoimmunity. To be fully active, immune T cells need a co-stimulatory signal in addition to the main antigen-driven signal. Abatacept modulates co-stimulation and prevents full T-cell activation. We evaluated the effect of abatacept in recent-onset type 1 diabetes.

METHODS

In this multicentre, double-blind, randomised controlled trial, patients aged 6-45 years recently diagnosed with type 1 diabetes were randomly assigned (2:1) to receive abatacept (10 mg/kg, maximum 1000 mg per dose) or placebo infusions intravenously on days 1, 14, 28, and monthly for a total of 27 infusions over 2 years. Computer-generated permuted block randomisation was used, with a block size of 3 and stratified by participating site. Neither patients nor research personnel were aware of treatment assignments. The primary outcome was baseline-adjusted geometric mean 2-h area-under-the-curve (AUC) serum C-peptide concentration after a mixed-meal tolerance test at 2 years' follow-up. Analysis was by intention to treat for all patients for whom data were available. This trial is registered at ClinicalTrials.gov, NCT00505375.

FINDINGS

112 patients were assigned to treatment groups (77 abatacept, 35 placebo). Adjusted C-peptide AUC was 59% (95% CI 6·1-112) higher at 2 years with abatacept (n=73, 0·378 nmol/L) than with placebo (n=30, 0·238 nmol/L; p=0·0029). The difference between groups was present throughout the trial, with an estimated 9·6 months' delay (95% CI 3·47-15·6) in C-peptide reduction with abatacept. There were few infusion-related adverse events (36 reactions occurred in 17 [22%] patients on abatacept and 11 reactions in six [17%] on placebo). There was no increase in infections (32 [42%] patients on abatacept vs 15 [43%] on placebo) or neutropenia (seven [9%] vs five [14%]).

INTERPRETATION

Co-stimulation modulation with abatacept slowed reduction in β-cell function over 2 years. The beneficial effect suggests that T-cell activation still occurs around the time of clinical diagnosis of type 1 diabetes. Yet, despite continued administration of abatacept over 24 months, the decrease in β-cell function with abatacept was parallel to that with placebo after 6 months of treatment, causing us to speculate that T-cell activation lessens with time. Further observation will establish whether the beneficial effect continues after cessation of abatacept infusions.

FUNDING

US National Institutes of Health.

Mitochondrial reactive oxygen species mediate GPCR-induced TACE/ADAM17-dependent transforming growth factor-alpha shedding

Epidermal growth factor receptor (EGFR) activation by GPCRs regulates many important biological processes. ADAM metalloprotease activity has been implicated as a key step in transactivation, yet the regulatory mechanisms are not fully understood. Here, we investigate the regulation of transforming growth factor-alpha (TGF-alpha) shedding by reactive oxygen species (ROS) through the ATP-dependent activation of the P2Y family of GPCRs. We report that ATP stimulates TGF-alpha proteolysis with concomitant EGFR activation and that this process requires TACE/ADAM17 activity in both murine fibroblasts and CHO cells. ATP-induced TGF-alpha shedding required calcium and was independent of Src family kinases and PKC and MAPK signaling. Moreover, ATP-induced TGF-alpha shedding was completely inhibited by scavengers of ROS, whereas calcium-stimulated shedding was partially inhibited by ROS scavenging. Hydrogen peroxide restored TGF-alpha shedding after calcium chelation. Importantly, we also found that ATP-induced shedding was independent of the cytoplasmic NADPH oxidase complex. Instead, mitochondrial ROS production increased in response to ATP and mitochondrial oxidative complex activity was required to activate TACE-dependent shedding. These results reveal an essential role for mitochondrial ROS in regulating GPCR-induced growth factor shedding.

Pediatric endocrinologists' management of children with type 2 diabetes

OBJECTIVE To understand physician behaviors and attitudes in managing children with type 2 diabetes. RESEARCH DESIGN AND METHODS A survey was mailed to a nationwide sample of pediatric endocrinologists (PEs). RESULTS A total of 40% of PEs surveyed responded (211 of 527). Concordance with current monitoring guidelines varied widely, ranging from 36% (foot care) to 93% (blood pressure monitoring). Given clinical vignettes addressing hyperlipidemia, hypertension, and microalbuminuria, only 34% of PEs were fully concordant with current treatment guidelines. Reported barriers included concerns about patient adherence, insufficient scientific evidence about treatment, and lack of familiarity with current recommendations. Providers aged < or =45 years or in clinical practice <10 years reported significantly more aggressive management behaviors and had higher concordance with guidelines. CONCLUSIONS Screening and management of pediatric type 2 diabetes varied widely among PEs, suggesting opportunities for quality improvement. More aggressive management of type 2 diabetes among younger providers may be related to recent training when type 2 diabetes was more common.

Clinical, genetic, and enzymatic characterization of P450 oxidoreductase deficiency in four patients

CONTEXT

P450 oxidoreductase (POR) deficiency causes disordered steroidogenesis; severe mutations cause genital ambiguity in both sexes plus the Antley-Bixler skeletal malformation syndrome, whereas mild mutations can cause adult infertility.

OBJECTIVE

We describe four patients with POR deficiency and identify and characterize the activities of their mutations. A 46,XY male with micropenis and two 46,XX female infants with genital ambiguity presented with skeletal malformations, and a 46,XX adolescent presented with primary amenorrhea, elevated 17alpha-hydroxyprogesterone, and low sex steroids.

METHODS

The coding regions of the POR gene were sequenced, and the identified mutations were recreated in human POR cDNA expression vectors lacking 27 N-terminal residues. POR and human P450c17 were expressed in bacteria. POR activity was measured by four assays: reduction of cytochrome c, oxidation of reduced nicotinamide adenine dinucleotide phosphate, and support of the 17alpha-hydroxylase and 17,20 lyase activities of P450c17.

RESULTS

All four patients were compound heterozygotes for POR mutations, including five novel mutations: L577R, N185K, delE217, and frameshift mutations 1363delC and 697-698insGAAC. N185K and delE217 lacked measurable activity in the assays based on P450c17 but retained partial activity in the assays based on cytochrome c. As assessed by V(max)/Km, L577R supported 46% of 17alpha-hydroxylase activity but only 27% of 17,20 lyase activity. Computational modeling of these novel mutants revealed the structural basis for their reduced or absent activities.

CONCLUSION

These patients illustrate the broad clinical spectrum of POR deficiency, including amenorrhea and infertility as the sole manifestation. POR assays based on P450c17 correlate well with hormonal and clinical phenotypes.

Self-management in type 2 diabetes: the adolescent perspective

PURPOSE

The purpose of this study was to document barriers and facilitators of self-management as perceived by adolescents with type 2 diabetes.

METHODS

Focus groups were conducted with adolescents diagnosed with type 2 diabetes. Adolescents aged 13 to 19 years were recruited from an academic medical center diabetes clinic. Between 2003 and 2005, 6 focus groups were used to elicit responses from the adolescents related to self-management of their diabetes. Questions were asked by trained group facilitators. Transcripts were coded by 3 reviewers. Qualitative analyses were conducted using NVIVO software.

RESULTS

A total of 24 adolescents participated in 6 focus groups. Coding resulted in 4 common domains affecting self-management: adolescent psychosocial development; the role of others with diabetes; environmental influences; and adolescents' problem-solving/coping skills. Adolescents identified both barriers to and facilitators of self-management within each domain. Barriers often related to social situations, embarrassment, seeking acceptance or perceived normalcy, and balancing competing interests. Adolescents viewed having another family member with diabetes as both a positive and a negative influence. Environmental influences, including school and family situations, had a large impact on self-management behaviors. Making sensible food choices was a common challenge. Descriptions of problem-solving or coping skills were limited, but cognitive techniques, such as reframing, were described.

CONCLUSION

Adolescents with type 2 diabetes identified many barriers to self-management, particularly related to interpersonal interactions, the influence of others with diabetes, and environmental influences. Results suggest that improving self-management in adolescents may require multimodal interventions to address individual, family, and social processes.

Cultured rat hepatocytes upregulate Akt and ERK in an ErbB-2-dependent manner

Epidermal growth factor (EGF) stimulates freshly plated adult hepatocytes to synthesize DNA, but only after they pass through a lag phase of 40 h following EGF exposure. The longer the cells are maintained, they become more responsive to EGF and the lag phase shortens. Maximal EGF-mediated stimulation of DNA synthesis requires the induction of ErbB2, which is not normally expressed in adult hepatocytes. We used immunological methods to demonstrate increased expression during culture of two gene families required for EGF to stimulate hepatocyte DNA synthesis: Akt and ERK 1/2. Both families showed hyperexpression in culture particularly when cells were exposed to insulin and EGF. Unlike CDK-2 and cyclin D1, integral mediators of the G1/S phase transition, ERK 1/2 and Akt appeared in the absence of EGF, particularly when insulin was present. This hyperexpression, which high concentrations of dexamethasone reversed, increased basal and growth factor-stimulated phosphorylation of Akt and ERK 1/2. Pharmacological blockade of phosphatidylinositol kinase suppressed the Akt increase whereas pharmacological blockade or small interfering RNA downregulation of ErbB2 inhibited both Akt and ERK 1/2 expression. All three Akt isoforms contributed to the increase in total Akt. EGF but not insulin specifically upregulated Akt 2 and 3. Since Akt and ERK 1/2 are also hyperexpressed in poorly differentiated hepatomas, their dysregulation in cancer may involve transcriptional mechanisms normally operative in cultured hepatocytes. We hypothesize that the induction and activation of ErbB2 increases the expression of these kinases, enhancing the responsiveness of hepatocytes to EGF as they adapt to culture.

Evidence of metabolic syndrome in lean children with premature pubarche at diagnosis

We investigated for evidence of early metabolic syndrome irrespective of body mass index (BMI) in subjects with premature pubarche (PP). Ten children with PP were compared with controls matched for age, sex, ethnicity, and BMI. Congenital adrenal hyperplasia and other known causes of PP were excluded by standard methods. Anthropometry, blood pressure (BP), dual-energy x-ray absorptiometry body scan, fasting blood lipid profile, and cytokines were obtained. The children were divided into 2 groups: (1) the total group of children with PP, and their age-, sex-, ethnicity-, and BMI-matched controls and (2) those with PP and normal BMI (<19 kg/m(2)) and their matched controls selected from the original groups. The PP subjects with normal BMI (S(1)) showed significantly higher systolic BP (P = .028), diastolic BP (P = .028), and mean arterial pressure (P = .018) compared with matched controls (C(1)). Nevertheless, for both groups, all the above parameters were statistically not significant when corrected for height. Fat distribution in PP subjects indicated significantly higher android (P = .047) and android-gynoid ratio (P = .013). Normal-BMI PP children had significantly higher android-gynoid ratio fat distribution compared with their matched controls (P = .037). Trunk fat percentage (p: 0.04) and trunk fat (grams) (P = .007) were significantly elevated in PP children compared with matched controls. Again, for both groups, all the above parameters were not statistically significant when corrected for height. The PP subjects had significantly higher tumor necrosis factor (TNF)-alpha (P = .038) and interleukin-8 (picograms per milliliter) (P = .05) compared with matched controls. Normal-BMI PP children also had higher TNF-alpha (P = .028) compared with matched controls. When corrected for height, TNF-alpha was higher in the total (P = .037) and normal-BMI (P = .043) PP children. Premature pubarche can be linked to markers of the metabolic syndrome in lean children.

Self-management behaviors, racial disparities, and glycemic control among adolescents with type 2 diabetes

OBJECTIVE

Type 2 diabetes is a growing problem among adolescents, but little is known about self-management behaviors in this population. Our aim was to examine self-management behaviors and glycemic control among adolescents with type 2 diabetes.

METHODS

From 2003 to 2005, a telephone survey of adolescents with type 2 diabetes was performed. Chart review obtained most recent glycated hemoglobin and clinical characteristics. Analyses compared patient characteristics and self-management behaviors to recent glycated hemoglobin levels.

RESULTS

Of 139 patients contacted, 103 (74%) completed the study. The mean age was 15.4 years: 69% were girls, 47% were white, and 46% were black. Mean glycated hemoglobin was 7.7%, and the average duration of diabetes was 2.0 years. More than 80% of patients reported > or = 75% medication compliance, and 59% monitored blood glucose > 2 times daily. However, patients reported frequent episodes of overeating, drinking sugary drinks, and eating fast food. More than 70% of patients reported exercising > or = 2 times a week, but 68% reported watching > or = 2 hours of television daily. Nonwhite patients had higher glycated hemoglobin and hospitalizations per year compared with white patients. In multivariable analyses, nonwhite race remained significantly associated with higher glycated hemoglobin even after adjusting for age, gender, BMI, insurance status, and other factors. Nonwhite patients were more likely to watch > or = 2 hours of television per day (78% vs 56%), to report exercising < or = 1 time per week (35% vs 21%), and to drink > or = 1 sugary drink daily (27% vs 13%).

CONCLUSION

Although patients reported good medication and monitoring adherence, they also reported poor diet and exercise habits and multiple barriers. Nonwhite race was significantly associated with poorer glycemic control even after adjusting for covariates. This may, in part, be related to disparities in lifestyle behaviors. Additional studies are indicated to further assess self-management behaviors and potential racial disparities in adolescents with type 2 diabetes.

Dexamethasone modulates ErbB tyrosine kinase expression and signaling through multiple and redundant mechanisms in cultured rat hepatocytes

Glucocorticoids paradoxically exert both stimulatory and inhibitory effects on the proliferation of cultured rat hepatocytes. We studied the effects of dexamethasone, a synthetic glucocorticoid, on the proliferation of cultured rat hepatocytes. The timing of growth factor addition modified the action of high-dose dexamethasone (10(-6) M) on DNA synthesis. When we added transforming growth factor-alpha at the time of plating, 10(-6) M dexamethasone weakly stimulated DNA synthesis by 26% relative to cells cultured in dexamethasone-free media. When we delayed growth factor addition until 24-48 h after plating, 10(-6) M dexamethasone inhibited DNA synthesis by 50%. Using immunological methods, we analyzed the expression and signaling patterns of the ErbB kinases in dexamethasone-treated cells. High-dose dexamethasone stabilized the expression of epidermal growth factor receptor (EGFr) and ErbB3, and it suppressed the de novo expression of ErbB2 that occurs during the third and fourth day of culture in 10(-8) M dexamethasone. High-dose dexamethasone by 72 h suppressed basal and EGF-associated phosphorylation of ERK and Akt. The reduction in ERK1/2 phosphorylation correlated with suppression of a culture-dependent increase in Son-of sevenless 1 (Sos1) and ERK1/2 expression. High-dose dexamethasone in hepatocytes stabilized or upregulated several inhibitory effectors of EGFr/ErbB2 and ERK, including receptor-associated late transducer (RALT) and MKP-1, respectively. Thus 10(-6) M dexamethasone exerts a time-dependent and redundant inhibitory effect on EGFr-mediated proliferative signaling in hepatocytes, targeting not only the ErbB proteins but also their various positive and negative effectors.

The emergence of ErbB2 expression in cultured rat hepatocytes correlates with enhanced and diversified EGF-mediated signaling

The proliferative effects of EGF in liver have been extensively investigated in cultured hepatocytes. We studied the effects of EGF, insulin, and other growth regulators on the expression, interaction, and signaling of ErbB receptors in primary cultures of adult rat hepatocytes. Using immunological methods and ErbB tyrosine kinase inhibitors, we analyzed the expression and signaling patterns of the ErbB kinases over 120 h of culture. Basal and EGF-stimulated protein tyrosine phosphorylation increased as cells adapted in vitro. EGF receptor (EGFr) expression declined in the first 24 h, whereas ErbB3 expression rose. Although ErbB2 was not present in freshly isolated hepatocytes, EGF and insulin independently induced ErbB2 while suppressing ErbB3 expression. Low concentrations of EGF and insulin synergistically stimulated ErbB2 expression and DNA synthesis. The greatest increase in ErbB2, which is normally expressed by fetal and neonatal hepatocytes, occurred shortly before the onset of DNA synthesis (> 40 h). EGF promoted EGFr and ErbB2 coassociation, stimulating tyrosine phosphorylation of both proteins. In contrast, heregulin beta1 (HRG-beta1) did not promote ErbB2 and ErbB3 coassociation. A selective tyrphostin inhibitor of ErbB2 suppressed EGF-stimulated DNA synthesis, but maximum suppression required the blockade of the EGFr kinase as well. Maximal EGF stimulation of DNA synthesis in vitro depends on the induction of ErbB2 and involves an EGFr-ErbB2 heterodimer. The ability of insulin to induce ErbB2 suggests both a mechanism for the synergy between insulin and EGF and a possible metabolic control of ErbB2 in vivo.

Parent perceptions of caring for adolescents with type 2 diabetes

OBJECTIVE

No studies have been performed to examine parent perceptions of caring for adolescents with type 2 diabetes. In this qualitative study, we examined parent perceptions of barriers and strategies to address barriers to self-care in adolescents with type 2 diabetes.

RESEARCH DESIGN AND METHODS

Families of adolescents with type 2 diabetes were recruited from a pediatric diabetes clinic. Focus groups were used to elicit parent experiences and perceptions of diabetes management of their adolescents with type 2 diabetes. Questions concerning barriers to self-care behaviors were asked by trained group facilitators. Transcripts were coded into themes by three reviewers. Qualitative analyses were conducted using NVIVO software.

RESULTS

Between 2003 and 2005, six focus groups were conducted with a total of 27 parents or guardians. Parents identified many barriers to and practical strategies for positive adolescent self-management. Five domains that influence self-management were identified: the role of others with diabetes, parenting skills, perceived lack of normalcy, environment, and adolescent development. Parents identified many barriers to dietary and exercise habits that were unique to the circumstances of adolescents with type 2 diabetes.

CONCLUSIONS

Parents identified many barriers to self-management that may be unique to adolescents with type 2 diabetes. The importance of others and environmental influences in the self-management behavior of adolescents with type 2 was evident. Interventions that are designed to improve self-management should include components that address multiple influences such as peers, school professionals, parents, siblings, and/or family systems.

Implementing pediatric growth charts into an electronic health record system

Electronic health record (EHR) systems are increasingly being adopted in pediatric practices; however, requirements for integrated growth charts are poorly described and are not standardized in current systems. The authors integrated growth chart functionality into an EHR system being developed and installed in a multispecialty pediatric clinic in an academic medical center. During a three-year observation period, rates of electronically documented values for weight, stature, and head circumference increased from fewer than ten total per weekday, up to 488 weight values, 293 stature values, and 74 head circumference values (p<0.001 for each measure). By the end of the observation period, users accessed the growth charts an average 175 times per weekday, compared to 127 patient visits per weekday to the sites that most closely monitored pediatric growth. Because EHR systems and integrated growth charts can manipulate data, perform calculations, and adapt to user preferences and patient characteristics, users may expect greater functionality from electronic growth charts than from paper-based growth charts.

Inactivation of TGF-beta signaling in hepatocytes results in an increased proliferative response after partial hepatectomy

The transforming growth factor beta (TGF-beta) signaling pathway, which is activated by the TGF-beta receptor complex consisting of type I and type II TGF-beta receptors (TGFBR1 and TGFBR2), regulates cell growth and death. TGF-beta and components of its signaling pathway, particularly TGFBR2, have been implicated as tumor suppressor genes and important antimitogenic factors in the gastrointestinal tract and liver. An in vivo approach to study these effects has been hindered by the embryonic lethality of Tgfbr2(-/-) mice and poor viability of the Tgfb1(-/-) mice. Consequently, we have developed a hepatocyte-specific Tgfbr2 knockout mouse, the Alb-cre Tgfbr2(flx/flx) mouse, to study the physiologically relevant effects of TGF-beta signaling on epithelial cell proliferation in vivo. After 70% hepatectomy, we observed increased proliferation and an increased liver mass : body weight ratio in the Alb-cre Tgfbr2(flx/flx) mice compared to Tgfbr2(flx/flx) mice. We also observed decreased expression and increased phosphorylation of p130 in the livers from the Alb-cre Tgfbr2(flx/flx) mice as well as increased expression of cyclin E, which is transcriptionally regulated, in part, by p130:E2F4. Consistent with these results, in a hepatocyte cell line derived from the Tgfbr2(flx/flx) mice, we found that TGF-beta increases the nuclear localization of E2F4, and presumably the transcriptional repression of the p130:E2F4 complex. Thus, we have demonstrated that TGF-beta signaling in vivo regulates the mitogenic response in the regenerating liver, affecting the liver mass : body weight ratio after partial hepatectomy, and that these mitogenic responses are accompanied by alterations in p130 expression and phosphorylation, implicating p130 as one of the proteins regulated in vivo by TGF-beta during liver regeneration.

Selective roles for tumor necrosis factor alpha-converting enzyme/ADAM17 in the shedding of the epidermal growth factor receptor ligand family: the juxtamembrane stalk determines cleavage efficiency

Epidermal growth factor (EGF) family ligands are derived by proteolytic cleavage of the ectodomains of integral membrane precursors. Previously, we established that tumor necrosis factor alpha-converting enzyme (TACE/ADAM17) is a physiologic transforming growth factor-alpha (TGF-alpha) sheddase, and we also demonstrated enhanced shedding of amphiregulin (AR) and heparin-binding (HB)-EGF upon restoration of TACE activity in TACE-deficient EC-2 fibroblasts. Here we extended these results by showing that purified soluble TACE cleaved single sites in the juxtamembrane stalks of mouse pro-HB-EGF and pro-AR ectodomains in vitro. For pro-HB-EGF, this site matched the C terminus of the purified human growth factor, and we speculate that the AR cleavage site is also physiologically relevant. In contrast, ADAM9 and -10, both implicated in HB-EGF shedding, failed to cleave the ectodomain or cleaved at a nonphysiologic site, respectively. Cotransfection of TACE in EC-2 cells enhanced phorbol myristate acetate-induced but not constitutive shedding of epiregulin and had no effect on betacellulin (BTC) processing. Additionally, soluble TACE did not cleave the juxtamembrane stalks of either pro-BTC or pro-epiregulin ectodomains in vitro. Substitution of the shorter pro-BTC juxtamembrane stalk or truncation of the pro-TGF-alpha stalk to match the pro-BTC length reduced TGF-alpha shedding from transfected cells to background levels, whereas substitution of the pro-BTC P2-P2' sequence reduced TGF-alpha shedding less dramatically. Conversely, substitution of the pro-TGF-alpha stalk or lengthening of the pro-BTC stalk, especially when combined with substitution of the pro-TGF-alpha P2-P2' sequence, markedly increased BTC shedding. These results indicate that efficient TACE cleavage is determined by a combination of stalk length and scissile bond sequence.

TACE/ADAM17 processing of EGFR ligands indicates a role as a physiological convertase

EGF family growth factors, including transforming growth factor-alpha (TGFalpha), amphiregulin (AR), and heparin-binding EGF (HB-EGF), are invariably expressed as transmembrane precursors that are cleaved at one or more sites in the extracellular domain to release soluble growth factor. Considerable attention has focused on the identification of proteases responsible for these processing events. We previously implicated tumor necrosis factor-alpha converting enzyme (TACE/ADAM17) in the generation of soluble TGFalpha from its transmembrane precursor, proTGFalpha. Here, we review our findings that primary keratinocytes from Tace(deltaZn/deltaZn) mice, which express a nonfunctional TACE, released dramatically lower levels of soluble TGFalpha compared to their normal counterparts, even though TGFalpha mRNA and cell-associated protein levels were similar in the two cell populations. Restoration of TACE activity in Tace(deltaZn/deltaZn) cells increased shedding of TGFalpha species, including the mature, 6-kDa protein. Further, exogenous TACE enzyme accurately cleaved the N-terminal processing site of proTGFalpha in cell lysates, as well as both physiologic sites of a soluble proTGFalpha ectodomain. TACE also accurately cleaved peptide substrates corresponding to the processing sites of several additional EGF family members, and restoration of TACE activity enhanced the shedding of soluble AR and HB-EGF proteins from Tace(deltaZn/deltaZn) cells. Finally, reduction of functional TACE gene dosage greatly exacerbated the open-eye defect of Egfr(wa-2/wa-2) newborns, which is regulated by redundant actions of several EGF family ligands. The implications of these results for the biology of the EGF family and TACE are discussed.

Diverse expression of ErbB receptor proteins during rat liver development and regeneration

BACKGROUND & AIMS

The protein expression and interactions of the ErbB receptors were examined in different liver proliferation models in vivo and in vitro, including ontogeny and regeneration following partial hepatectomy.

METHODS

Expression and tyrosine phosphorylation status of specific ErbB proteins were studied by immunologic methods.

RESULTS

The epidermal growth factor receptor, ErbB2, and ErbB3 were the only ErbB proteins detected in the liver parenchyma on embryonic day 19. ErbB2 disappeared by the third week after birth and could not be appreciably induced in the adult animal by partial hepatectomy. ErbB2 was also detected in multipotent stem (RLE) and hepatoma (H4IIe) cell lines as well as in fetal, but not adult, hepatocyte cultures. Only epidermal growth factor receptor and ErbB3 were detected in adult liver, and both showed circadian variation in protein expression. ErbB4 was not detected in any model. Patterns of ligand-induced ErbB phosphorylation differed between fetal and adult hepatocytes.

CONCLUSIONS

Complex and independent programs regulate the ErbB receptors, with implications for differential cell signaling in hepatic development and regeneration.

Premature pubarche in girls is associated with functional adrenal but not ovarian hyperandrogenism

OBJECTIVE

We hypothesized that there would be evidence of functional ovarian hyperandrogenism in girls with premature pubarche (PP) at diagnosis.

METHODS

White girls <8 years of age and black girls <6 years with PP (n = 15) were studied. Prepubertal girls (n = 13; 5.3-10.9 years) and early pubertal girls (n = 8) served as control subjects. The biochemical marker for functional ovarian hyperandrogenism was the 17-hydroxyprogesterone (17-OHP), androstenedione (AD), and estradiol (E2) response to subcutaneous leuprolide during adrenal suppression with dexamethasone. This was studied in girls with PP and in control subjects.

RESULTS

ACTH stimulated 17-hydroxypregnenolone (17-OH Preg), dehydroepiandrosterone (DHEA), and AD levels, and 17-OH Preg:17-OHP and DHEA:AD ratios were significantly higher in girls with PP than in prepubertal control subjects (n = 18) (P < or =.003). The ovarian response to leuprolide stimulation was comparable in girls with PP and prepubertal control subjects, but the response in prepubertal study subjects was significantly lower than in pubertal control subjects (P =.016 for Delta17-OHP, P =.001 for DeltaAD, and P =.026 for DeltaE2).

CONCLUSIONS

Contrary to the hypothesis, PP in girls was not associated with prepubertal evidence of ovarian hyperandrogenism but was associated with functional adrenal hyperandrogenism.

Tumor necrosis factor-alpha converting enzyme (TACE) regulates epidermal growth factor receptor ligand availability

We previously implicated tumor necrosis factor-alpha converting enzyme (TACE/ADAM17) in the processing of the integral membrane precursor to soluble transforming growth factor-alpha (TGF-alpha), pro-TGF-alpha. Here we examined TGF-alpha processing in a physiologically relevant cell model, primary keratinocytes, showing that cells lacking TACE activity shed dramatically less TGF-alpha as compared with wild-type cultures and that TGF-alpha cleavage was partially restored by infection of TACE-deficient cells with TACE-encoding adenovirus. Moreover, cotransfection of TACE-deficient fibroblasts with pro-TGF-alpha and TACE cDNAs increased shedding of mature TGF-alpha with concomitant conversion of cell-associated pro-TGF-alpha to a processed form. Purified TACE accurately cleaved pro-TGF-alpha in vitro at the N-terminal site and also cleaved a soluble form of pro-TGF-alpha containing only the ectodomain at the C-terminal site. In vitro, TACE accurately cleaved peptides corresponding to cleavage sites of several epidermal growth factor (EGF) family members, and transfection of TACE into TACE-deficient cells increased the shedding of amphiregulin and heparin-binding EGF (HB-EGF) proteins. Consistent with the hypothesis that TACE regulates EGF receptor (EGFR) ligand availability in vivo, mice heterozygous for Tace and homozygous for an impaired EGFR allele (wa-2) were born with open eyes significantly more often than Tace(+/+)Egfr(wa-2)(/)(wa-2) counterparts. Collectively, these data support a broad role for TACE in the regulated shedding of EGFR ligands.

Integral role of the EGF receptor in HGF-mediated hepatocyte proliferation

Hepatocyte growth factor (HGF), insulin, and TGF-alpha stimulate DNA synthesis in cultured hepatocytes. Each ligand activates a distinct tyrosine kinase receptor, although receptor cross-talk modulates signaling. In rat hepatocytes, HGF can stimulate TGF-alpha production while TGF-alpha antibodies or antisense oligonucleotides suppress HGF-stimulated DNA synthesis. We report that the epidermal growth factor receptor (EGFR) kinase inhibitor PKI166 blocked both basal and ligand-induced tyrosine phosphorylation of the EGFR (IC(50) = 60 nM), but not of the insulin receptor or c-met. Pharmacologic inhibition of the EGFR kinase abolished the proliferative actions of HGF and EGF, but not insulin, whereas PI-3 kinase inhibition blocked both EGF and insulin actions. We conclude that in cultured hepatocytes (i) PI-3 kinase is required for EGF- and insulin-induced proliferation and (ii) EGFR mediates both the basal rate of DNA synthesis and that induced by EGF and HGF, but not insulin. The mitogenic effect of HGF may be secondary to increased synthesis or processing of EGFR ligands such as TGF-alpha.

Insulin and heregulin-beta1 upregulate guanylyl cyclase C expression in rat hepatocytes: reversal by phosphodiesterase-3 inhibition

Guanylyl cyclase C (GC-C) is the receptor for the hormones guanylin and uroguanylin. Although primarily expressed in the rat intestine, GC-C is also expressed in the liver during neonatal or regenerative growth or during the acute phase response. Little is known about the hepatic regulation of GC-C expression. The influence of various hepatic growth or acute phase regulators on GC-C expression was evaluated by immunoblot analysis of protein from primary rat hepatocytes grown in a serum-free medium. Insulin and heregulin-beta1 strongly stimulated GC-C expression by 24 h of cell culture. Several different hormones and agents suppressed this action, including transforming growth factor beta (TGF-beta), as well as inhibitors of phosphatidylinositol 3-kinase (PI-3-kinase) and phosphodiesterase 3 (PDE-3, an insulin- and PI-3-kinase-dependent enzyme). The compartmental downregulation of cAMP levels by PDE-3 may be a critical step in the hormonal action that culminates in GC-C synthesis.

Reversible G(1) arrest induced by inhibition of the epidermal growth factor receptor tyrosine kinase requires up-regulation of p27(KIP1) independent of MAPK activity

We have used quinazoline inhibitors of the epidermal growth factor receptor (EGFR) tyrosine kinase to study the link between EGFR signaling and G(1) to S traverse. Treatment of A431 and MDA-468 human tumor cells with 0.1-10 microM AG-1478 inhibited basal and ligand-stimulated EGFR phosphorylation without a decrease in receptor content, EGF-binding sites, or binding affinity. Incubation of A431 cells with 0.1-1 microM AG-1517 abrogated (125)I-EGF internalization. Both AG-1478 and AG-1517 markedly inhibited A431 and MDA-468 colony formation in soft agarose at concentrations between 0.01 and 1 microM. Daily injections of AG-1478 at 50 mg/kg delayed A431 tumor formation in athymic nude mice. A transient exposure of A431 cells to AG-1478 resulted in a dose-dependent up-regulation of the cyclin-dependent kinase inhibitor p27, down-regulation of cyclin D1 and of active MAPK, and hypophosphorylation of the retinoblastoma protein (Rb). These changes were temporally associated with recruitment of tumor cells in G(1) phase and a marked reduction of the proportion of cells in S phase. Upon removal of the kinase inhibitor, EGFR and Rb phosphorylation and the levels of cyclin D1 protein were quickly restored, but the cells did not reenter S phase until p27 protein levels were decreased. Phosphorothioate p27 oligonucleotides decreased p27 protein in A431 cells and abrogated the quinazoline-mediated G(1) arrest. Treatment of A431 cells with PD 098509, a synthetic inhibitor of MEK1, inhibited MAPK activity without inducing G(1) arrest or increasing the levels of p27. However, treatment with LY 294002, an inhibitor of phosphatidylinositol 3-kinase (PI3K), inhibited basal Akt activity, up-regulated p27, and recruited cells in G(1). These data suggest that p27 is required for the growth arrest that follows interruption of the EGFR kinase in receptor-overexpressing cells. In addition, the G(1) arrest and up-regulation of p27 resulting from EGFR blockade are not due to the interruption of MAPK, but to the interruption of constitutively active PI3K function.

Liver regeneration is transiently impaired in urokinase-deficient mice

To test the hypothesis that urokinase-type plasminogen activator (uPA) plays an important role in liver regeneration in vivo, partial hepatectomy was performed on wild-type and uPA-deficient (uPA-/-) mice. Mice were studied at 24, 44, and 96 h and at 8 days and 4 wk post-partial hepatectomy for evidence of regeneration, as measured by mitotic indexes and [3H]thymidine incorporation. In wild-type mice, thymidine incorporation peaked at 44 h and this index was reduced by 47% in uPA-/- mice (P = 0.02). By 8 days, however, liver mass was comparable in both groups. Histological analysis revealed the presence of focal areas of fibrin deposition and cellular loss by 24 h that were more severe and prevalent in uPA-/- mice than in wild-type mice (62 and 23%, respectively; chi2 = 3.939, P = 0.047). In contrast, regeneration was not impaired in uPA receptor (uPAR)-deficient mice at 24 and 44 h. Taken together, these data indicate that uPA, independent of its interaction with the uPAR, plays an important role in liver regeneration in vivo.

An essential role for ectodomain shedding in mammalian development

The ectodomains of numerous proteins are released from cells by proteolysis to yield soluble intercellular regulators. The responsible protease, tumor necrosis factor-alpha converting enzyme (TACE), has been identified only in the case when tumor necrosis factor-alpha (TNFalpha) is released. Analyses of cells lacking this metalloproteinase-disintegrin revealed an expanded role for TACE in the processing of other cell surface proteins, including a TNF receptor, the L-selectin adhesion molecule, and transforming growth factor-alpha (TGFalpha). The phenotype of mice lacking TACE suggests an essential role for soluble TGFalpha in normal development and emphasizes the importance of protein ectodomain shedding in vivo.