Pharmacodynamic differences between canagliflozin and dapagliflozin: results of a randomized, double-blind, crossover study.

AIMS: To compare the pharmacodynamic effects of the highest approved doses of the sodium glucose co-transporter 2 (SGLT2) inhibitors canagliflozin and dapagliflozin on urinary glucose excretion (UGE), renal threshold for glucose excretion (RTG ) and postprandial plasma glucose (PPG) excursion in healthy participants in a randomized, double-blind, two-period crossover study. METHODS: In each treatment period, participants (n = 54) received canagliflozin 300 mg or dapagliflozin 10 mg for 4 days (20 min before breakfast). A mixed-meal tolerance test (600 kcal; 75 g glucose) was performed at baseline and on day 4 of each treatment period to assess changes in incremental PPG (PPGΔAUC0-2 h ). We measured 24-h UGE and plasma glucose on day 4 to determine 24-h mean RTG . RESULTS: Canagliflozin 300 mg and dapagliflozin 10 mg had similar effects on UGE and RTG for 4 h after dosing, but canagliflozin was associated with higher UGE and greater RTG reductions for the remainder of the day. Mean 24-h UGE was ∼25% higher with canagliflozin than with dapagliflozin (51.4 vs. 40.8 g), and 24-h mean RTG was ∼0.4 mmol/l (7 mg/dl) lower with canagliflozin than with dapagliflozin (3.79 vs. 4.17 mmol/l; p < 0.0001). Dapagliflozin had no effect on PPG excursion; canagliflozin delayed and reduced PPG excursion (between-treatment difference in PPGΔAUC0-2 h from baseline expressed as a percentage of baseline mean, -10.2%; p = 0.0122). Canagliflozin and dapagliflozin were generally well tolerated. CONCLUSIONS: In healthy participants, canagliflozin 300 mg provided greater 24-h UGE, a lower RTG and smaller PPG excursions than dapagliflozin 10 mg.

Effect of the sodium glucose co-transporter 2 inhibitor canagliflozin on plasma volume in patients with type 2 diabetes mellitus.

AIM: To evaluate the effects of canagliflozin on plasma volume, urinary glucose excretion (UGE), fasting plasma glucose (FPG), glycated haemoglobin (HbA1c) and additional measures of fluid/electrolyte balance in patients with type 2 diabetes on background therapy with metformin and angiotensin-converting enzyme inhibitors or angiotensin receptor blockers. METHODS: Patients (N = 36) were randomized (1:1) to receive canagliflozin 300 mg or placebo for 12 weeks. Pharmacodynamic parameters were assessed at baseline and at weeks 1 and 12. RESULTS: Increased 24-h UGE was seen in the canagliflozin group compared with a reduction in the placebo group at both week 1 (91.8 vs. -2.4 g) and week 12 (82.6 vs. -0.4 g). Canagliflozin also reduced both FPG and HbA1c. Reductions in body weight and blood pressure were observed at weeks 1 and 12. Canagliflozin decreased plasma volume compared with an increase with placebo at week 1 (-5.4 vs. 4.3%; p = 0.02), but this was largely attenuated at week 12 (4.6 vs. 5.8%; p = 0.76). A modest numerical increase in urine volume was observed with canagliflozin at week 1 that was attenuated at week 12; other measures of volume status (i.e. blood urea nitrogen, serum creatinine and haematocrit) remained modestly increased with canagliflozin at week 12. CONCLUSION: Canagliflozin provided sustained effects on UGE and FPG over 12 weeks and a transient reduction in plasma volume that was largely attenuated by week 12.

CCR2 antagonism in patients with type 2 diabetes mellitus: a randomized, placebo-controlled study.

AIMS: Macrophage recruitment through C-C motif chemokine receptor-2 (CCR2) into adipose tissue is believed to play a role in the development of insulin resistance and type 2 diabetes mellitus (T2DM). The objective of this Phase 2 proof-of-concept study was to evaluate the safety, tolerability, pharmacokinetics and pharmacodynamics of JNJ-41443532, an orally bioavailable CCR2 antagonist, in patients with T2DM. METHODS: This was a 4-week, double-blind, placebo-controlled, randomized, multicenter study. A total of 89 patients were randomized to receive either 250- or 1000-mg of JNJ-41443532 twice daily, 30-mg of pioglitazone once daily (reference arm), or placebo. The primary endpoint was change from baseline in 23-h weighted mean glucose (WMG); secondary endpoints included change from baseline in fasting plasma glucose (FPG), insulin resistance (Homeostatic Model Assessment [HOMA-IR]), insulin secretion (HOMA-%B) and body weight. RESULTS: Absorption of JNJ-41443532 into the systemic circulation occurred at a median tmax of 2 h, and the mean t½ was approximately 8 h for both doses; plasma systemic exposures increased slightly more than dose-proportionally. After 4 weeks, reductions in 23-h WMG and FPG were observed in all treatment groups compared with placebo and were significantly lower for 250-mg JNJ-41443532 and pioglitazone. HOMA-IR was lower for all treatment groups, but significantly lower only for pioglitazone. Conversely, HOMA-%B was increased for all groups, but significantly increased only for 250-mg JNJ-41443532. All groups, including placebo, had decreased body weight over time. There were no clinically significant findings during routine safety assessments and the incidence of treatment-emergent adverse events was similar across all groups. CONCLUSIONS: Administration of JNJ-41443532 resulted in modest improvement in glycaemic parameters compared with placebo, and was generally well tolerated in patients with T2DM.

Effects of JNJ-38431055, a novel GPR119 receptor agonist, in randomized, double-blind, placebo-controlled studies in subjects with type 2 diabetes.

AIM: G-protein coupled receptor agonists are currently under investigation for their potential utility in patients with type 2 diabetes mellitus (T2DM). The objective was to determine the pharmacokinetics, pharmacodynamics, safety and tolerability of GPR119 agonist, JNJ-38431055 in T2DM subjects. METHODS: This was a randomized, double-blind, placebo- and positive-controled, single-dose cross-over study and a randomized, double-blind, placebo-controled multiple-dose parallel design study. The study was conducted at 4 US research centres. Two different experiments involving 25 and 32 different subjects were performed in male and female subjects, aged 25-60 years, mean body mass index between 22 and 39.9 kg/m2 who had T2DM diagnosed 6 months to 10 years before screening. JNJ-38431055 (100 and 500 mg) or sitagliptin (100 mg) as a single-dose or JNJ-38431055 (500 mg) once daily for 14 consecutive days were tested. Effects on stimulated plasma glucose, insulin, C-peptide and incretin concentrations were pre-specified outcomes. RESULTS: JNJ-38431055 was well tolerated and not associated with hypoglycaemia. Plasma systemic exposure of JNJ-38431055 increased as the dose increased, was approximately two-fold greater after multiple-dose administration, and attained steady-state after approximately 8 days. Compared with placebo, single-dose administration of oral JNJ-38431055 decreased glucose excursion during an oral glucose tolerance test, but multiple-dose administration did not alter 24-h weighted mean glucose. Multiple dosing of JNJ-38431055 increased post-meal total glucagon-like peptide 1 and gastric insulinotropic peptide concentrations compared to baseline. CONCLUSIONS: These studies provide evidence of limited glucose lowering and incretin activity for JNJ-38431055 in subjects with T2DM.

Canagliflozin, a novel inhibitor of sodium glucose co-transporter 2, dose dependently reduces calculated renal threshold for glucose excretion and increases urinary glucose excretion in healthy subjects.

Canagliflozin, a potent, selective sodium glucose co-transporter 2 inhibitor in development for treatment of type 2 diabetes, lowers plasma glucose (PG) by lowering the renal threshold for glucose (RT(G) ) and increasing urinary glucose excretion (UGE). An ascending single oral-dose phase 1 study investigated safety, tolerability and pharmacodynamics of canagliflozin in healthy men (N = 63) randomized to receive canagliflozin (n = 48) or placebo (n = 15). Canagliflozin (10, 30, 100, 200, 400, 600 or 800 mg q.d. or 400 mg b.i.d.) was administered to eight cohorts (six subjects/cohort: canagliflozin; two subjects/cohort: placebo). Dose dependently, canagliflozin decreased calculated 24-h mean RT(G) with maximal reduction to approximately 60 mg/dl, and increased mean 24-h UGE. At doses >200 mg administered before breakfast, canagliflozin reduced postprandial PG and serum insulin excursions at that meal. Canagliflozin was generally well tolerated; most adverse events were mild and no hypoglycaemia was reported. These results support further study of canagliflozin.

Orthopedic injuries associated with jet-skis (personal watercrafts): A review of 127 inpatients.

BACKGROUND: Personal watercrafts (PWC) account for a disproportionate amount of water based injuries. Current literature suggests those with less PWC experience are more at risk for injury. Previous studies have not specifically evaluated the orthopedic implications of PWC usage or how various mechanisms of injury (MOI) contribute to different injury patterns. HYPOTHESIS: PWC injuries will frequently require orthopedic intervention. The presence of an orthopedic injury will result in increased injury severity score (ISS), hospital and intensive care unit (ICU) length of stay (LOS). Patients visiting our region will have less PWC experience and so are more prone to serious injuries. MATERIALS AND METHODS: Retrospective cohort study at a single Level 1 trauma center of admitted patients sustaining PWC injuries from 02/2004-03/2017. The following were studied: demographics, mechanism, season, ISS, hospital and ICU LOS, follow-up, fracture characteristics and management. RESULTS: Hundred and twenty-seven patients were admitted due to PWC injury, 66 (52.0%) sustained an orthopedic injury, totaling 103 fractures (48 [46.6%] lower extremity, 26 [25.2%] upper extremity, 14 [13.6%] vertebral, 11 [10.7%] pelvic ring and 4 [3.9%] acetabulum). The mean age of orthopedic patients was 29 years (range 8-62). Handle bar injuries were significantly associated with open fractures, (13 of 25 open fractures, 3 of which became infected). Injuries occurring during the winter were associated with a higher ISS, yet more injuries occurred in the summer. A patient being a "visitor" to the region did not influence ISS. The mean LOS was 12.6 days for orthopedic patients. Eighteen orthopedic patients (27.3%) required ICU admission and 36 (54.5%) patients required orthopedic surgery (mean 2.11 operations). DISCUSSION: A majority of PWC injuries resulted in extremity fractures with a moderate percentage requiring orthopedic surgery. Correlations between PWC experience and injury incidence can provide information for increased safety. LEVEL OF EVIDENCE: IV; retrospective.

Vanadate normalizes hyperglycemia in two mouse models of non-insulin-dependent diabetes mellitus.

We have studied the effects of oral administration of vanadate, an insulinometic agent and a potent inhibitor of phosphotyrosyl protein phosphatase (PTPase) in vitro, on blood glucose and PTPase action, in two hyperinsulinemic rodent models of non-insulin-dependent diabetes mellitus (NIDDM). Oral administration of vanadate (0.25 mg/ml in the drinking water) to ob/ob mice for 3 wk lowered blood glucose level from 236 +/- 4 to 143 +/- 2 mg/dl without effect on body weight. Administration of vanadate to db/db mice produced a similar effect. Electron microscopic examination revealed no signs of hepatotoxicity after 47 d of treatment. There was a slight reduction in insulin receptor autophosphorylation when tested by immunoblotting with antiphosphotyrosine antibody after in vivo stimulation, and the phosphorylation of the endogenous substrate of the insulin receptor, pp185, was markedly decreased in the ob/ob mice. Both cytosolic and particulate PTPase activities in liver of ob/ob mice measured by dephosphorylation of a 32P-labeled peptide corresponding to the major site of insulin receptor autophosphorylation were decreased by approximately 50% (P less than 0.01). In db/db diabetic mice, PTPase activity in the cytosolic fraction was decreased to 53% of control values (P less than 0.02) with no significant difference in the particulate PTPase activity. Treatment with vanadate did not alter hepatic PTPase activity as assayed in vitro, or receptor and substrate phosphorylation as assayed in vivo, in ob/ob mice despite its substantial effect on blood glucose. These data indicate that vanadate is an effective oral hypoglycemic treatment in NIDDM states and suggest that its major effects occurs distal to the insulin receptor tyrosine kinase.

Regulation of insulin receptor substrate-1 in liver and muscle of animal models of insulin resistance.

Insulin rapidly stimulates tyrosine phosphorylation of a protein of approximately 185 kD in most cell types. This protein, termed insulin receptor substrate-1 (IRS-1), has been implicated in insulin signal transmission based on studies with insulin receptor mutants. In the present study we have examined the levels of IRS-1 and the phosphorylation state of insulin receptor and IRS-1 in liver and muscle after insulin stimulation in vivo in two rat models of insulin resistance, i.e., insulinopenic diabetes and fasting, and a mouse model of non-insulin-dependent diabetes mellitus (ob/ob) by immunoblotting with anti-peptide antibodies to IRS-1 and anti-phosphotyrosine antibodies. As previously described, there was an increase in insulin binding and a parallel increase in insulin-stimulated receptor phosphorylation in muscle of fasting and streptozotocin-induced (STZ) diabetic rats. There was also a modest increase in overall receptor phosphorylation in liver in these two models, but when normalized for the increase in binding, receptor phosphorylation was decreased, in liver and muscle of STZ diabetes and in liver of 72 h fasted rats. In the hyperinsulinemic ob/ob mouse there was a decrease in insulin binding and receptor phosphorylation in both liver and muscle. The tyrosyl phosphorylation of IRS-1 after insulin stimulation reflected an amplification of the receptor phosphorylation in liver and muscle of hypoinsulinemic animals (fasting and STZ diabetes) with a twofold increase, and showed a significant reduction (approximately 50%) in liver and muscle of ob/ob mouse. By contrast, the levels of IRS-1 protein showed a tissue specific regulation with a decreased level in muscle and an increased level in liver in hypoinsulinemic states of insulin resistance, and decreased levels in liver in the hyperinsulinemic ob/ob mouse. These data indicate that: (a) IRS-1 protein levels are differentially regulated in liver and muscle; (b) insulin levels may play a role in this differential regulation of IRS-1; (c) IRS-1 phosphorylation depends more on insulin receptor kinase activity than IRS-1 protein levels; and (d) reduced IRS-1 phosphorylation in liver and muscle may play a role in insulin-resistant states, especially of the ob/ob mice.

Insulin receptor signaling in the beta-cell influences insulin gene expression and insulin content: evidence for autocrine beta-cell regulation.

The insulin receptor (IR) is expressed by insulin-secreting beta-cells, but its cellular function is unknown. We transfected betaTC6-F7 beta-cells with cDNAs encoding either wild-type or mutant kinase-inactive (A/K1018) IRs, and by fluorescence-activated cell sorting generated polyclonal beta-cell lines that overexpressed each receptor type at levels two- to fourfold higher than the parental cells. Beta-cells overexpressing wild-type IRs had a proportional increase in insulin-stimulated tyrosine kinase activity; no change occurred in beta-cells expressing the mutant IR. We observed a threefold increase in cellular insulin content in beta-cells that overexpressed the wild-type IR, as determined by radioimmunoassay. This increase occurred despite a fivefold elevated rate of both basal and 10 mmol/l glucose-induced insulin secretion. Fractional insulin secretion (percentage of total cell insulin releasable at 10 mmol/l glucose) was unchanged in beta-cells overexpressing the wild-type IR compared with the parental beta-cell line. Insulin content and insulin secretion were unaffected by overexpression of kinase-inactive IRs. Steady-state insulin mRNA levels were elevated twofold in the beta-cells overexpressing the wild-type IR and unchanged in the beta-cells expressing the kinase-inactive receptor, as determined by Northern blot analysis. The rate of insulin mRNA degradation measured in the presence of 5 microg/ml actinomycin D was not significantly affected in either cell line. In the absence of glucose, the basal level of (pro)insulin biosynthesis in the beta-cells overexpressing the wild-type IR increased significantly (61%) compared with the beta-cells transfected with the kinase-inactive IR. These data indicate that IR signaling can regulate insulin gene transcription and can modulate the steady-state insulin content of beta-cells.

Glucose-induced insulin receptor tyrosine phosphorylation in insulin-secreting beta-cells.

In the beta TC3 insulin-secreting beta-cell line, glucose rapidly induces the tyrosine phosphorylation of the 97-kDa insulin receptor beta-subunit. Phosphorylation is transient, with fourfold stimulation by 2 min and subsequent dephosphorylation to basal levels by 10-15 min. Elevating the extracellular KCl concentration equipotently initiates receptor phosphorylation. Preventing insulin secretion with 1 mumol/l epinephrine or by removing extracellular Ca2+ blocks the effect. In the absence of glucose-induced secretion, exogenous insulin also stimulated insulin receptor autophosphorylation transiently and with an ED50 of 4 x 10(-9) mol/l. In addition, functional insulin-like growth factor I (IGF-I) receptors are also expressed by these beta-cells, as indicated by IGF-I-induced receptor tyrosine phosphorylation (ED50 = 5 x 10(-9) mol/l) and also by detection of hybrid insulin/IGF-I receptor autophosphorylation at 10(-7) mol/l IGF-I. Both glucose and insulin stimulate the tyrosine phosphorylation of the insulin receptor substrate (IRS) IRS-1 and increase by two- to fivefold the rapid association of IRS-1 with the 85-kDa alpha-subunit of the phosphatidylinositol-3-kinase, as determined by co-immunoprecipitation assays. These results demonstrate that in these beta-cells, glucose-induced insulin secretion activates the beta-cell surface insulin receptor tyrosine kinase and its intracellular signal transduction pathway, suggesting a new autocrine mechanism for the regulation of beta-cell function.

Expression of insulin receptor mRNA and insulin receptor substrate 1 in pancreatic islet beta-cells.

The expression of insulin receptor mRNA was examined in rat pancreatic islet cells by single-cell reverse transcriptase (RT)-polymerase chain reaction (PCR). Single cells from disaggregated islets were individually isolated in a microcapillary pipet, and the beta-cells were identified by amplification of the mRNA for insulin. We found that in single beta-cells, the mRNA for the insulin receptor was also expressed. The fraction of single islet cells expressing both insulin receptor and insulin mRNAs corresponds closely to the fraction of beta-cells in the disaggregated islet cell preparation. These results indicate that normal beta-cells have the potential to express authentic insulin receptors. Immunohistochemical analysis was insufficiently sensitive for assaying insulin receptor protein; however, insulin receptor substrate 1 (IRS-1) was readily immunolocalized in islet beta-cells. Since IRS-1 links several cell surface receptors, including those for insulin and IGF-I, to distal signal transduction pathways, our observations indicate that hormonal regulation of islet beta-cells potentially involves the same signal transduction pathway that mediates insulin and growth factor signaling in peripheral insulin target tissue cell types.

Wortmannin inhibits insulin secretion in pancreatic islets and beta-TC3 cells independent of its inhibition of phosphatidylinositol 3-kinase.

Glucose is the primary stimulus for insulin secretion by pancreatic beta-cells, and it triggers membrane depolarization and influx of extracellular Ca2+. Cholinergic agonists amplify insulin release by several pathways, including activation of phospholipase C, which hydrolyzes membrane polyphosphoinositides. A novel phospholipid, phosphatidylinositol 3,4,5- trisphosphate [PtdIns(3,4,5)P3], a product of phosphatidylinositol 3-kinase (PI 3-kinase), has recently been found in various cell types. We demonstrate by immunoblotting that PI 3-kinase is present in both cytosolic and membrane fractions of insulin-secreting beta-TC3 cells and in rat islets. The catalytic activity of PI 3-kinase in immunoprecipitates of islets and beta-TC3 cells was measured by the production of radioactive phosphatidylinositol 3-monophosphate from phosphatidylinositol (PtdIns) in the presence of [gamma-32P]ATP. Wortmannin, a fungal metabolite, dose dependently inhibited PI 3-kinase activity of both islets and beta-TC3 cells, with an IC50 of 1 nmol/l and a maximally effective concentration of 100 nmol/l, when it was added directly to the kinase assay. However, if intact islets were incubated with wortmannin and PI 3-kinase subsequently was determined in islet immunoprecipitates, approximately 50% inhibition of PI 3-kinase activity (but no inhibition of glucose- and carbachol-stimulated insulin secretion) from intact islets was obtained at wortmannin concentrations of 100 nmol/l. Wortmannin, at higher concentrations (1 and 10 micromol/l), inhibited glucose- and carbachol-induced insulin secretion of Intact rat islets by 58 and 92%, respectively. Wortmannin had no effect on the basal insulin release from rat islets. A similar dose curve of inhibition of glucose- and carbachol-induced insulin secretion by wortmannin was obtained when beta-TC3 cells were used. Cellular metabolism was, not changed by any wortmannin concentrations tested (0.01-10 micromol/l). Both basal cytosolic [Ca2+]i and carbamyl choline-induced increases of [Ca2]i were unaffected by wortmannin in the presence of 2.5 mmol/l Ca2+, while Ca2+ mobilization from intracellular stores was partially decreased by wortmannin. Together, these data suggest that wortmannin at concentrations that inhibit PI 3-kinase does not affect insulin secretion. PI 3-kinase is unlikely to have a major role in insulin secretion induced by glucose and carbachol.

Pharmacokinetics, pharmacodynamics, safety, and tolerability of JNJ-38431055, a novel GPR119 receptor agonist and potential antidiabetes agent, in healthy male subjects.

The incidence of type 2 diabetes mellitus is increasing worldwide. Several G-protein-coupled receptor agonists are being studied for their efficacy as antidiabetes agents. JNJ-38431055 is a novel, potent, and orally available selective agonist of the glucose-dependent insulinotropic (GPR119) receptor. Double-blind, randomized, placebo-controlled studies were conducted to evaluate the safety, tolerability, pharmacokinetics, and pharmacodynamics of single oral doses of JNJ-38431055 (2.5-800 mg) in healthy male volunteers. The systemic exposure of JNJ-38431055 in plasma increased in proportion to the dose and was not influenced by coadministration of food. The terminal elimination half-life was ~13 h when administered as an oral suspension formulation. JNJ-38431055 was well tolerated and was not associated with hypoglycemia. As compared with placebo, single-dose oral JNJ-38431055 increased postmeal plasma glucagon-like peptide 1 (GLP-1), glucose-dependent insulinotropic peptide (GIP), and peptide YY (PYY) concentrations but did not significantly decrease glucose excursion or increase insulin secretion. However, in a graded glucose infusion study, JNJ-38431055 was shown to induce a higher insulin secretion rate (ISR) relative to placebo at elevated plasma glucose levels. These studies provide evidence for the potential efficacy of JNJ-38431055 as an antidiabetes agent in humans.

Effect of aprepitant on the pharmacokinetics and pharmacodynamics of warfarin.

OBJECTIVE: To examine the effect of aprepitant on the pharmacokinetics and pharmacodynamics of warfarin. Aprepitant is a neurokinin-1 (NK1)-receptor antagonist developed as an antiemetic for chemotherapy-induced nausea and vomiting. METHODS: This was a double-blind, placebo-controlled, randomized, two-period, parallel-group study. During period 1, warfarin was individually titrated to a stable prothrombin time (expressed as international normalized ratio, INR) from 1.3 to 1.8. Subsequently, the daily warfarin dose remained fixed for 10-12 days. During period 2, the warfarin dose was continued for 8 days, and on days 1-3 administered concomitantly with aprepitant (125 mg on day 1, and 80 mg on days 2 and 3) or placebo. At baseline (day -1 of period 2) and on day 3, warfarin pharmacokinetics was investigated. INR was monitored daily. During period 2, warfarin trough concentrations were determined daily. RESULTS: The study was completed by 22 healthy volunteers (20 men, 2 women). On day 3, steady-state pharmacokinetics of warfarin enantiomers after aprepitant did not change, as assessed by warfarin AUC(0-24 h) and C(max). However, compared with placebo, trough S(-) warfarin concentrations decreased on days 5-8 (maximum decrease 34% on day 8, P<0.01). The INR decreased after aprepitant with a mean maximum decrease on day 8 of 11% versus placebo (P=0.011). CONCLUSION: These data are consistent with a significant induction of CYP2C9 metabolism of S(-) warfarin by aprepitant. Subsequently, in patients on chronic warfarin therapy, the clotting status should be monitored closely during the 2-week period, particularly at 7-10 days, following initiation of the 3-day regimen of aprepitant with each chemotherapy cycle.

Employment patterns of male methadone maintenance patients.

The employment patterns of 342 male methadone maintenance patients who remained in treatment for at least 1 year are examined. Four periods in the patients' lives are considered: (1) the period before addiction, (2) the period of addiction, (3) the time of entry into the treatment program, and (4) the first treatment year. Although more than three-quarters of the patients were employed regularly during the period before addiction, only about one-quarter were employed while addicted. At entry into the program 15% were employed, and 25% worked regularly during the first treatment year. An examination of some semographic, social, and work-related correlates of employment status during each period revealed that factors such as ethnicity, educational attainment, marital status, alcohol use, previous employment, and attitudes toward work were all important in relation to patients' employment status at one or more of the four periods. The treatment program had only a moderate impact on patients' attitudes toward work and employment behavior.

Insulin inhibits pertussis toxin-catalyzed ADP-ribosylation of G-proteins. Evidence for a novel interaction between insulin receptors and G-proteins.

Insulin modifies cellular responsiveness to some hormones which operate via guanine nucleotide binding proteins (G-proteins); also, G-proteins have been implicated in some actions of insulin. Using pertussis toxin-catalyzed [32P]ADP-ribosylation of Gi as an index of G-protein conformation, we evaluated interaction of insulin receptors with G-proteins. In isolated rat liver plasma membranes, insulin treatment for 10 min inhibited [32P]ADP-ribosylation of Gi by 50%. This effect was half-maximal at 2 x 10(-8) M. A similar effect was observed with rat adipocyte plasma membranes with half-maximal effect at 1 x 10(-8) M. Pertussis toxin activity itself was uninfluenced by insulin, as ribosylation of tubulin or heat-treated bovine serum albumin was unaltered. Elevated Mg2+ diminished basal ADP-ribosylation, but insulin inhibition occurred at all Mg2+ levels between 0 and 1 mM. Insulin inhibition was independent of ATP (20 microM to 10 mM), and GTP (0-100 microM) concentrations. Because both protein kinase C and purified insulin receptor phosphorylate purified Gi in vitro, we examined Gi as a substrate for the insulin receptor tyrosine kinase in vivo. Triton-extracts of isolated rat hepatocytes which had been 32Pi labeled and treated with insulin were immunoprecipitated with a polyclonal anti-Gi antiserum. The dominant labeled phosphoprotein had a molecular weight of 42 kDa, consistent with the alpha-subunit of Gi, contained only phosphoserine, and was unaffected in its phosphorylation by insulin. These results indicate the existence of a novel pathway for physiological "cross-talk" between insulin and other hormones and further suggests that the insulin receptor may interact with regulatory G-proteins via biochemical mechanisms not directly involving the tyrosine kinase activity of the insulin receptor.

Serum and epidermal growth factor transiently depolarize quiescent BSC-1 epithelial cells.

Continuous intracellular recording of membrane potential with microelectrodes in BSC-1 epithelial cells has been used to study the early ionic effects of the interaction of mitogens with cell surface receptors. Initial results show that (i) there is no significant difference in membrane potential between growing and quiescent cells, (ii) addition of epidermal growth factor or serum to quiescent BSC-1 cells induces a brief and transient depolarization, (iii) the mitogenic response of BSC-1 cells to epidermal growth factor and the transient depolarization show similar concentration dependences, and (iv) serum addition to quiescent BSC-1 cells induces a sustained increase in Na+ influx that is electroneutral and amiloride sensitive. Intracellular pH changes may be a primary event triggering the response of quiescent cells to mitogenic polypeptides.

The relationship between age of mother and child health and development.

This study investigates the relationship between age of mother and children's health and development at birth and at approximately three years of age. The sample is composed of Black and Hispanic women and their firstborn children who were delivered on the wards of a large New York City hospital in 1975. There were no differences between children of teenage and older mothers in terms of prematurity or birthweight, but the children of younger mothers had higher Apgar scores than those of older mothers. Age of mother was not significantly related to hospitalizations, the need to see a physician regularly, or abnormal weight. Although the number of injurious conditions and the incidence of burns were higher among the children of adolescent mothers, the effect of age of mother was not independent of other factors. The children of teenage mothers scored better than those of older mothers on the total Denver Developmental Screening Test, as well as on the Fine Motor sector. These findings thus suggest that when relevant background characteristics are controlled, children of teenage mothers are as healthy and develop as well as children of older mothers.