Measuring pre-hepatic insulin secretion using a population model of C-peptide kinetics: accuracy and required sampling schedule

The accuracy of calculations of pre-hepatic insulin secretion were investigated, to provide independent validation of a population model of C-peptide kinetics. The effects of sampling frequency were also assessed. Five normal subjects (aged 28 to 43 years; BMI (kg/m2) 20.5 to 24.5) and five subjects with non-insulin-dependent diabetes mellitus (NIDDM) treated by diet alone (aged 34 to 57 years; BMI 22.6 to 25.6) were given a variable intravenous infusion of biosynthetic human C-peptide (BHCP) (t=-60 to 240 min) mimicking meal stimulated C-peptide secretion, with short-term oscillations (peak approximately every 12 min) superimposed on the infusion profile. Plasma C-peptide was measured every 5 min (t=0 to 240 min). The BHCP infusion was reconstructed from C-peptide measurements using a population model of C-peptide kinetics and a deconvolution method. Bias, defined as the percentage difference between the total amount of calculated BHCP and the total amount of infused BHCP (t=0 to 240 min), indicated that overall C-peptide secretion can be measured with 14% [95% confidence interval (CI) -11 to 39%] and 21% (95% CI -3 to 45%) accuracy in normal subjects and subjects with NIDDM respectively. Accuracy was not reduced by reducing the sampling frequency to every 30 min. The root mean square error, measuring the average deviation between the infused and normalised calculated BHCP profiles, was also independent of the sampling frequency [mean (95% CI) 0.9 (0.3 to 1.6) pmol/kg per min in normal subjects; 1.0 (0.9 to 1.1) pmol/kg per min in subjects with NIDDM]. Deconvolution employing a population model of C-peptide kinetics can be used to estimate postprandial total C-peptide secretion with biases of 14% and 22% respectively in normal subjects and subjects with NIDDM. Plasma C-peptide samples need only be drawn every 30 minutes.

Establishing the dose response curve for metabolic control with troglitazone, an insulin action enhancer, in type 2 diabetes patients

Troglitazone is a novel once-daily oral antidiabetic agent for the treatment of type 2 diabetes patients. Here, we report the overall dose response characteristics of troglitazone, with respect to effects on metabolic control, using a pharmacodynamic model. Data from week 12 from two previously reported double-blind, randomized, parallel-group, placebo-controlled, dose-ranging multicentre studies examining once-daily doses of 10, 30, 100, 200, 400, 600 and 800 mg of troglitazone were combined for the analyses. The pharmacodynamic relationships for relevant parameters of metabolic control were modelled using a nonlinear regression modelling programme. The troglitazone dose-concentration relationship was linear over 10-800 mg. Using an inhibitory sigmoid Emax model, ED50 values of approximately 100 mg and 200 mg were found for fasting serum glucose and triglycerides, respectively. The 200 mg dose for HbA1c showed an inconsistent reduction compared with placebo between the two studies; this illustrates the difficulties associated with comparing results from different assay techniques. Insulin and nonesterified fatty acid reductions compared with placebo were not consistent between studies, and no pharmacodynamic modelling was possible. No changes in body weight were observed at any dose. Troglitazone was as well tolerated as placebo across the dose range investigated. This pharmacodynamic analysis has established that 200-600 mg once daily can be considered the therapeutic dose range of troglitazone that significantly improves metabolic control in type 2 diabetes patients.

Reproducibility and comparability of insulin sensitivity indices measured by stable-label intravenous glucose tolerance test

We have investigated the reproducibility of (1) insulin sensitivity (S*I) and glucose effectiveness (S*G) as measured by the stable-label (one compartment) minimal model, and (2) insulin sensitivity (S*Ib), plasma clearance rate (PCR), basal hepatic output (HGOb), and total hepatic glucose output (HGO0-240) as measured by the novel stable-label two compartment model of glucose disappearance during labelled intravenous glucose tolerance test (IVGTT) using 6,6-(2)H-glucose. Ten normal male subjects were studied on two occasions one week apart. Both models provided estimates of all indices with acceptable precision (CV of parameter estimates < or =50%). The within subject CVs of S*I and S*Ib were comparable (17% vs 19%) as were the within subject CVs of S*G and PCR (13% vs 16%). A highly significant linear relationship was observed between S*Ib and S*I (0.303 +/- 0.046 ml kg(-1) min(-1) per mU l(-1) vs 13.04 +/- 1.89 10(-4) min(-1) per mU l(-1), y = 0.0037 x + 0.0002, r = 0.90, p < 0.001; mean +/- SE), but not between PCR and S*G (1.98 +/- 0.15 ml kg(-1) min(-1) vs 0.0089 +/- 0.0005 min(-1), rs = 0.34, NS). The two compartment model provided a plausible time-profile of hepatic glucose output during IVGTT, reproducible estimates of HGOb (1.96 +/- 0.18 mg kg(-1) min(-1), 15%; mean +/- SE, within subject CV), and a highly reproducible HGO0-240 (7%; within subject CV). We conclude that the stable-label (one compartment) minimal model and the stable-label two compartment model provide reproducible estimates of parameters of glucose kinetics in normal subjects. Insulin sensitivity indices estimated by the two models are strongly linearly related.

Which environmental variables are related to the onset of seasonal affective disorder?

The regular fall-winter onset of seasonal affective disorder is believed to be related to seasonal changes in the environment. However, the high correlation among various environmental variables has made it difficult to distinguish which ones may play a causal role. Photoperiod should explain variations in onset risk across both latitude and day of the year because it varies as a function of only these 2 factors. In Study 1, the authors found this to be the case using data from 5 locations. Environmental factors that vary from year to year should explain variations in onset risk across both time of year and actual year. In Study 2, the authors examined data from 7 years at 1 location and failed to find evidence of this effect for daily hours of sunshine, mean daily temperature, and total daily radiation. Findings support photoperiod as being related to the onset of seasonal affective disorder.

Concomitant administration of cholestyramine influences the absorption of troglitazone

AIM

Troglitazone is an orally active anti-diabetic agent. Cholestyramine is an orally administered lipid-lowering agent which acts by binding to bile acids and removing them from enterohepatic circulation. Preclinical studies suggesting the potential for an interaction between troglitazone and cholestyramine require confirmation in a clinical setting.

METHODS

In vitro and in vivo experiments in the dog were carried out prior to a clinical study. Twelve healthy volunteers (mean age 32 years, range 20-44 years) each received a single oral dose of troglitazone 400 mg alone and with cholestyramine 12 g (taken 1 h after troglitazone) in an open, two-way crossover study.

RESULTS

In vitro, about 99% of troglitazone was adsorbed by cholestyramine at an incubate concentration of 3 microg ml(-1) whilst at 500 microg ml(-1) adsorption fell to about 90%. In vivo, AUC of troglitazone was reduced by an average of 42% (22.7 vs 12.2 microg ml(-1) h (95% CI for difference 28-57, P=0.01) in 11 beagle dogs receiving troglitazone 200 mg and cholestyramine 1 g compared with control values. Mean maximum plasma concentration (Cmax) was 49% of control values (7.08 vs 3.42 microg ml(-1) (95% CI for difference 14-85, P=0.05)). In the clinical study median AUC for troglitazone and its two major metabolites were statistically significantly lower when troglitazone was administered with cholestyramine (17.9 vs 5.2 microg ml(-1) h (95% CI for difference -20.5, -8.7), 133.7 vs 27 1 microg ml(-1) h (-166.4, -67.8) and 18.4 vs 2.5 microg ml(-1) h (-21.6, -10.6) for troglitazone, sulphate and quinone metabolite respectively (all P < 0.01) representing percentage decreases of 71, 80 and 86% respectively. A statistically significant reduction was also observed in Cmax for the sulphate metabolite (4.56 vs 1.28 microg ml(-1) (95% CI for difference -4.42, -1.99, P < 0.01)), but not for troglitazone (1.85 vs 1.23 microg ml(-1) (-1.13, 0.49) or the oxidative metabolite (0.84 vs 0.45 microg ml(-1) (-0.77, 0.09)).

CONCLUSIONS

The results were indicative of an alteration in the extent of troglitazone's absorption. Concomitant administration of troglitazone and cholestyramine could severely impair troglitazone's clinical utility as an antihyperglycaemic agent.

Improvement in the gastrointestinal absorption of troglitazone when taken with, or shortly after, food

AIMS

Troglitazone, an insulin action enhancing agent, is currently in clinical development for the treatment of non insulin dependent diabetes mellitus. The objective of this study was to establish the effect of food on the systemic absorption and metabolism of troglitazone.

METHODS

After an overnight fast, 12 healthy male volunteers each received, in random order, troglitazone (400 mg orally) alone, concomitantly with (at the start of), and 30 min after, a standardized diabetic breakfast as part of a three-period crossover study.

RESULTS

When troglitazone was administered with or after food, geometric mean values of area under the plasma concentration-time curves (AUC[last]) relative to fasting state were increased significantly by 59% in both cases (95% CI 1-150%, P=0.046 and 2-148%, P=0.040) with values of 11.4, 11.5 and 7.2 microg ml(-1) h respectively. Maximum observed plasma concentration (Cmax) increased by 96% and 72% (95% CI 29-197%, P=0.003 and 15-158%, P=0.011) with values of 2.2, 2.0 and 1.1 microg ml(-1) respectively. Changes in t(lag) were not clinically significant. Increases in AUC(0, infinity) for the main circulating sulphate metabolite relative to fasting were also significant (41%, 95% CI 5-89%, P=0.025 and 34%, 95% CI 1-79%, P= 0.044 respectively) with values of 82.6, 78.6 and 58.5 microg h ml(-1). Cmax increased by 68% (95%, CI 10-156%, P=0.019) and 65% (95% CI 9-149%, P=0.020) with values of 3.2, 3.1 and 1.9 microg ml(-1) respectively. Reductions in t1/2 (16 and 21%, 95% CI 0-30, 6-33) although statistically significant (P=0.050 and P=0.009) were not clinically significant with values of 22.3, 20.4 and 24.5 h for with food, after food and fasting respectively. Troglitazone was well tolerated in all cases throughout the study with a trend for improved tolerability of gastrointestinal symptoms when taken 30 min after a meal.

CONCLUSIONS

The absorption of troglitazone is enhanced significantly by food with little effect on the main metabolic pathway. Increased absorption of troglitazone in the presence of food is likely to be a consequence of enhanced solubility in bile combined with an increase in dissolution time. On the basis of these findings, troglitazone should be taken either with, or up to 30 min after, food.

Expression of p53, PCNA, and C-erbB-2 in Barrett's metaplasia and adenocarcinoma

We sought to determine if an immunohistochemical panel of p53, PCNA, and c-erbB-2 was a useful biomarker of transformation in Barrett's metaplasia. P53, PCNA, and c-erbB-2 immunohistochemistry was performed on resected Barrett's specimens selected to show discrete grades of dysplasia and then on prospectively obtained biopsies. In resection specimens, p53 was positive in 36% with no dysplasia, in 30% with low-grade dysplasia, in 85% with high-grade dysplasia, and in 90% of adenocarcinomas. While an evaluation of proliferation throughout the specimen did not differ between groups, surface proliferation was significantly higher in high-grade dysplasia than in low-grade or no dysplasia. All high-grade dysplasia specimens were positive for at least one marker, compared to 44% with no or low-grade dysplasia. C-erbB-2 was only seen in 31% with high-grade dysplasia and in 10% of adenocarcinomas. Prospectively, the panel had a sensitivity of 100%, a specificity of 81% and an overall accuracy of 83% in identifying patients who developed high-grade dysplasia or cancer. Thus, overexpression of p53 occurs early in the malignant transformation of Barrett's and increases with histologic progression, and proliferation at the surface of Barrett's epithelium increases with progressive grades of dysplasia. An immunohistochemical panel of p53 and PCNA is a useful biomarker for Barrett's metaplasia.

Which environmental variables are related to the onset of seasonal affective disorder?

The regular fall-winter onset of seasonal affective disorder is believed to be related to seasonal changes in the environment. However, the high correlation among various environmental variables has made it difficult to distinguish which ones may play a causal role. Photoperiod should explain variations in onset risk across both latitude and day of the year because it varies as a function of only these 2 factors. In Study 1, the authors found this to be the case using data from 5 locations. Environmental factors that vary from year to year should explain variations in onset risk across both time of year and actual year. In Study 2, the authors examined data from 7 years at 1 location and failed to find evidence of this effect for daily hours of sunshine, mean daily temperature, and total daily radiation. Findings support photoperiod as being related to the onset of seasonal affective disorder.

A 5-nanosecond molecular dynamics trajectory for B-DNA: analysis of structure, motions, and solvation

We report the results of four new molecular dynamics (MD) simulations on the DNA duplex of sequence d(CGCGAATTCGCG)2, including explicit consideration of solvent water, and a sufficient number of Na+ counterions to provide electroneutrality to the system. Our simulations are configured particularly to characterize the latest MD models of DNA, and to provide a basis for examining the sensitivity of MD results to the treatment of boundary conditions, electrostatics, initial placement of solvent, and run lengths. The trajectories employ the AMBER 4.1 force field. The simulations use particle mesh Ewald summation for boundary conditions, and range in length from 500 ps to 5.0 ns. Analysis of the results is carried out by means of time series for conformationalm, helicoidal parameters, newly developed indices of DNA axis bending, and groove widths. The results support a dynamically stable model of B-DNA for d(CGCGAATTCGCG)2 over the entire length of the trajectory. The MD results are compared with corresponding crystallographic and NMR studies on the d(CGCGAATTCGCG)2 duplex, and placed in the context of observed behavior of B-DNA by comparisons with the complete crystallographic data base of B-form structures. The calculated distributions of mobile solvent molecules, both water and counterions, are displayed. The calculated solvent structure of the primary solvation shell is compared with the location of ordered solvent positions in the corresponding crystal structure. The results indicate that ordered solvent positions in crystals are roughly twice as structured as bulk water. Detailed analysis of the solvent dynamics reveals evidence of the incorporation of ions in the primary solvation of the minor groove B-form DNA. The idea of localized complexation of otherwise mobile counterions in electronegative pockets in the grooves of DNA helices introduces an additional source of sequence-dependent effects on local conformational, helicoidal, and morphological structure, and may have important implications for understanding the functional energetics and specificity of the interactions of DNA and RNA with regulatory proteins, pharmaceutical agents, and other ligands.

Meta-analysis of steady-state pharmacokinetics of troglitazone and its metabolites

The object of this study is to evaluate the effects of age, gender, age-by-gender interaction, Type II diabetes, body weight, race, smoking, and formulation on steady-state pharmacokinetics of troglitazone, Metabolite 1 (sulfate conjugate), and Metabolite 3 (quinone metabolite) following multiple-dose oral administration of troglitazone. Pharmacokinetic parameter estimates [Cl/F (apparent oral clearance), AUC0-24 (area under plasma concentration-time curve), and ratio of AUC for troglitazone to Metabolite 1 and to Metabolite 3] obtained from 84 healthy volunteers and 171 patients with Type II diabetes in 8 studies were analyzed using a graphical method (for race and smoking) or a weighted ANCOVA model incorporating gender, health status (healthy vs Type II diabetes), and formulation as main effects; age, age-by-gender interaction, and body weight as continuous covariates. Ratio of AUC for troglitazone to metabolites was also examined by inspection of log-probit plots. Age, gender, age-by-gender, Type II diabetes, and formulation had negligible effects on troglitazone Cl/F, AUC0-24 (all analytes), and AUC ratio of troglitazone to metabolites. Race and smoking did not appear to influence steady-state pharmacokinetics of troglitazone and its metabolites. Although body weight was a significant covariate for AUC0-24 and Cl/F, the explanatory power of the overall model was weak (R2 < 0.2). Log-probit plots did not reveal a polymorphic distribution in AUC ratio of troglitazone to Metabolite 1 or Metabolite 3. Based on pharmacokinetics, dose adjustment for troglitazone in relation to the demographic factors examined is not required due to their poor predictive ability on steady-state pharmacokinetics of troglitazone and its metabolites.

Management of sports-related anterior cruciate ligament injuries

Injuries from recreational and competitive sports activities have increased significantly during the past two decades. The anterior cruciate ligament (ACL) is one of the most commonly injured knee ligament in athletes. As the ACL is the knee's primary intra-articular stabilizer, injuries to this ligament can seriously alter athletes' physical activity levels or end their sports careers. The medical and surgical treatment options for a sports-related ACL injury depend upon the age of the patient, the type and degree of the ACL injury, and the anticipated future activity level of the athlete. This article describes the anatomy and physiology of the knee joint, the different types and degrees of ACL injuries, diagnostic measures for ACL injuries, and treatment options, which include arthroscopically assisted ACL reconstruction procedures with autologous patellar tendon grafts. Preoperative, intraoperative, and postoperative nursing interventions, rehabilitation regimens, and sports injury prevention measures are discussed.

Wheat middlings in high-concentrate diets: feedlot performance, carcass characteristics, nutrient digestibilities, passage rates, and ruminal metabolism in finishing steers

We conducted two experiments to determine the feeding value and effects on diet digestibilities, passage rates, and ruminal metabolism of wheat middlings (WM) fed as a replacement for either the concentrate or roughage components of finishing diets of steers. In Exp. 1, 120 medium-framed steers were blocked by weight and randomly allocated to one of six treatments of high-concentrate diets: control (0%); 5, 10, or 15% pelleted WM replacing dry-rolled corn (DRC); and 5 or 10% pelleted WM replacing chopped alfalfa hay (ALF) components of the diet. Increasing WM replacement of DRC increased DMI (P < .01) and feed:gain ratio (FG; P < .05) linearly. A 9.2% increase in daily DMI and 10.1% increase in FG were observed at 15% of WM. Daily gain and final weight of the steers were not influenced by WM replacement of DRC. The WM replacement of ALF decreased (P < .01) daily DMI linearly, but it had no effect on ADG, final weight, or FG. In Exp. 2, six medium-framed steers, fitted with ruminal cannulas, were used in a 6 x 6 Latin square design with the same treatments as described in Exp. 1. Dry matter, OM, and starch digestibilities decreased (P < .01) by increasing replacement of DRC with WM, and replacing ALF increased DM and OM digestibilities linearly (P < .01). Wheat middlings could replace only up to 5% of DRC without reducing feed conversion efficiency and diet digestibilities, but complete (100%) or partial (50%) replacement of ALF increased digestibilities of DRC finishing diets.

Constant infusion and bolus injection of stable-label tracer give reproducible and comparable fasting HGO

We have investigated the reproducibility of fasting hepatic glucose output (HGO) estimates by use of isotope dilution methodology of stable-label tracers. Six normal subjects were studied on two occasions 1 wk apart. After an overnight fast, the subjects received a bolus injection of 7 mg/kg of [U-13C]glucose and, simultaneously, a primed constant infusion of 0.05 mg.kg-1.min-1 of [6,6(-2)H]glucose. The bolus injection provided one estimate of HGO (HGOBOL), and the constant infusion provided two estimates of HGO, namely, HGO at 2 h (HGOINF2) and HGO at 4 h (HGOINF4), both with the assumption of steady-state conditions. All estimates were similar in value; HGOBOL was highest, followed by HGOINF2 and HGOINF4 [2.30 +/- 0.11 (SE), 2.17 +/- 0.12, and 2.01 +/- 0.13 mg.kg-1.min-1]. The constant infusion gave highly reproducible results. In the case of HGOINF2, the within-subject coefficient of variation (CV) was only 3% compared with 5% of HGOINF4. The reproducibility of HGOBOL was comparable with the within-subject CV of 7%. We conclude that a constant infusion and a bolus injection of stable-label tracer give reproducible and comparable estimates of HGO.

Vagal regulation during bottle feeding in low-birthweight neonates: support for the gustatory-vagal hypothesis

The gustatory-vagal hypothesis proposes that gustatory stimulation elicits a coordinated vagal response manifested as an increase in ingestive behaviors (e.g., sucking) and a decrease in nucleus ambiguus vagal tone measured by decreases in the amplitude of respiratory sinus arrhythmia (RSA). The current study tested the gustatory-vagal hypothesis in a bottle feeding paradigm with 29 clinically stable, high-risk, low-birthweight neonates. The amplitude of respiratory sinus arrhythmia (RSA) was collected before, during, and after bottle feeding. Consistent with the gustatory-vagal hypothesis, RSA decreased during bottle feeding. In a longitudinal subsample of subjects, the pattern of RSA changes during the feeding paradigm was stable across two test sessions.

Cardioprotection with a novel adenosine regulating agent mediated by intravascular adenosine

Adenosine is cardioprotective in models of myocardial stunning and infarction, but the precise compartment within the heart in which adenosine elicits its cardioprotective effects has not been determined. The goals of the present study were to (i) investigate the effects of a novel adenosine regulating agent, GP531 (5-amino-1-beta-n-(5-benzylamino-5-deoxyribofuranosyl) imidazole-4-carboxamide), on post-ischemic myocardial function, and (ii) examine the contribution of endogenous adenosine in the intravascular and interstitial compartments in mediating the beneficial effects. Pigs were instrumented for measurement of myocardial segment shortening, and for sampling of coronary venous blood and myocardial interstitial fluid for determination of adenosine concentration. Myocardial dysfunction was induced by 4 x 8 min coronary occlusions, and recovery of regional function was monitored for 2 h. In control pigs, function recovered to 24 +/- 2% of baseline after 2 h. Treatment with GP531 improved functional recovery to 55 +/- 3%. GP531-mediated cardioprotection was prevented by adenosine receptor blockade with 8-sulfophenyltheophylline (23 +/- 2%). GP531 did not affect basal adenosine levels, but caused a 2-fold greater increase in vascular adenosine concentration with ischemia (54.6 +/- 10.6 vs. 28.1 +/- 8.0 microM in controls. P < 0.05). In contrast, the interstitial adenosine concentration was not significantly different in treated vs. untreated control pigs (9.4 +/- 3.9 vs. 15.0 +/- 1.8 microM in controls). These data indicate that (1) GP531 improves recovery of myocardial function following ischemia reperfusion injury via an adenosine receptor-dependent mechanism, and (2) the cardioprotection is associated with increased intravascular, but not interstitial, adenosine concentration during ischemia. Therefore, we conclude that cardioprotection elicited by GP531-enhanced endogenous adenosine is dependent on an intravascular site of action.

Latex allergy. Considerations for the care of pediatric patients and employee safety

Certain groups of patients and health care workers are at high risk for developing latex allergy. In the perioperative arena, there is an increased risk for this allergy due to the mode and frequency of latex exposure. Using a multidisciplinary team approach, nurses must institute policies and procedures for precautions to take with latex to ensure that patients and employees remain in a safe environment. Through education, research and collaboration with industry and health care professionals, latex sensitization can be minimized, and latex allergic reactions avoided.

Gastrointestinal manifestations of scleroderma

The gastrointestinal tract is commonly involved in SSc. The esophagus is the most frequently affected, followed by the anorectal region, the small bowel, stomach, and colon. Smooth muscle atrophy and to a lesser degree fibrosis is the underlying defect responsible for the resulting abnormalities. These smooth muscle alterations have a significant impact on gastrointestinal motility, which results in secondary disorders of GER, pseudo-obstruction, bacterial overgrowth, and disordered bowel functions. The clinical presentation for these conditions ranges from asymptomatic to life-threatening. Thus, gastrointestinal evaluation and treatment of these conditions is an important aspect in the management of patients with SSc.

Stable trait components of hopelessness: baseline and sensitivity to depression

Hopelessness (H) plays an important theoretical and practical role in depression. The authors hypothesized that a patient's H is comprised of (a) a baseline level of H when not depressed and (b) an increment in H related to the severity of depression at the time and the person's rate of increase in H as a function of severity of depression (sensitivity). Baseline and sensitivity are explanatory stable traits; H and depression are observed, time-varying states. The corresponding statistical model described well the longitudinal data of 316 participants. Baseline and sensitivity were uncorrelated and correlated with different clinical and demographic variables. Baseline predicted a future suicide attempt; sensitivity and H when depressed did not. It may be useful to ask "How hopeless is this person when not depressed and how much more hopeless is he or she when depressed?", rather than simply "How hopeless is this depressed person?"

ISEC: a program to calculate insulin secretion

ISEC (Insulin SECretion) is a computer program which calculates pre-hepatic insulin secretion from plasma C-peptide measurements. The program uses a regression (population) model to derive parameters of C-peptide kinetics from subject's gender, type (normal, obese, non-insulin dependent diabetes mellitus), age, weight, and height. Insulin secretion is calculated as a piece-wise constant (step) function with flexible step length allowing for a fine resolution of the secretion profile between measurements. A constrained regularisation method of deconvolution is employed to carry out the calculations. The calculated profile satisfies three properties: (i) it fits the measurement within the given level of the measurement error, (ii) it is non-negative, and (iii) it has a minimum value of a regularisation criterion (norm of second differences) which quantifies the degree of deviation of the secretion profile from a straight line. Both theoretical aspects and specific features related to ISEC are considered. To exemplify the use of ISEC, pre-hepatic insulin secretion is calculated during meal tolerance test, frequently sampled intravenous glucose tolerance test, hyperinsulinaemic euglycaemic glucose clamp, and basal conditions with frequent sampling.

Chief residency in PM&R. A balance of education and administration

The role of the Physical Medicine and Rehabilitation (PM&R) chief resident (CR) in physiatry residency education programs is the subject of annual deliberation in many academic centers. A national survey of PM&R programs was conducted to determine CR number, selection method, responsibilities, duration of service, and postresidency destiny. The questionnaire generated a response rate of 86% with 90% of programs reporting 1-3 CRs per year. A range of 1-11 CRs were selected annually per program. The most common methods of CR selection were faculty vote (45%), combined resident-faculty vote (22%), and other (33%). The prevalence of administrative responsibilities included orienting new residents (97%), formulating call schedules (92%), dispute mediation (88%), medical student-residency interviews (87%), rotation schedule configuration (64%), faculty meeting participation (61 %), social event promotion (59%), and elective and externship schedule development (31 %). Educational duties included teaching and organizing didactics (87%), organizing pharmaceutical and rehabilitation equipment inservices (77%), arranging didactics (77%), board review coordination (72%), arranging grand round speakers (66%), core curriculum lectures (61%), and facilitating resident research (37%). CR career goals included group practice (48%), academic faculty (29%), solo practice (5%), and fellowship (18%). Overall, PM&R CRs maintain considerable involvement in the educational aspects of residency training, although their clinical and administrative duties predominate. Although the PM&R CRs contribute significantly to the academic growth and development of their respective training programs, only a modest percentage (47%) of CRs choose to remain in academic physiatry via an attending (29%) or fellowship (18%) position.

Stable trait components of hopelessness: baseline and sensitivity to depression

Hopelessness (H) plays an important theoretical and practical role in depression. The authors hypothesized that a patient's H is comprised of (a) a baseline level of H when not depressed and (b) an increment in H related to the severity of depression at the time and the person's rate of increase in H as a function of severity of depression (sensitivity). Baseline and sensitivity are explanatory stable traits; H and depression are observed, time-varying states. The corresponding statistical model described well the longitudinal data of 316 participants. Baseline and sensitivity were uncorrelated and correlated with different clinical and demographic variables. Baseline predicted a future suicide attempt; sensitivity and H when depressed did not. It may be useful to ask "How hopeless is this person when not depressed and how much more hopeless is he or she when depressed?", rather than simply "How hopeless is this depressed person?"