Monoclonal antibodies to the insulin receptor mimic metabolic effects of insulin but do not stimulate receptor autophosphorylation in transfected NIH 3T3 fibroblasts

The metabolic actions of insulin and anti-insulin receptor monoclonal antibodies were compared with their effects on insulin receptor phosphorylation in mouse NIH 3T3 fibroblasts transfected with human insulin receptor cDNA. In serum-starved NIH 3T3 HIR3.5 cells, uptake of 2-deoxy-[3H]glucose was stimulated up to 2-fold after 30 min with insulin, with a half-maximal effect at 0.1 nM insulin. Incorporation of [3H]thymidine was stimulated approximately 12-fold after a 16-hr preincubation with insulin, with a half-maximal effect at 2 nM insulin. Phosphorylation of insulin receptor beta-subunit in cells prelabeled with [32P]phosphate was increased 10- to 20-fold within 5 min of adding insulin, with a half-maximal effect at approximately 3 nM insulin. Monoclonal antibodies reacting with four different epitopes on the insulin receptor mimicked the effect of insulin on 2-deoxyglucose uptake. These antibodies also stimulated thymidine incorporation, although the maximum stimulation was only approximately 30% that of insulin. Two antibodies (25-49 and 83-14) showed a similar concentration dependence to insulin in their metabolic effects and in the inhibition of 125I-labeled insulin binding to cells. The other two antibodies (83-7 and 18-44) were somewhat less potent and did not inhibit insulin binding. None of the antibodies significantly increased insulin receptor phosphorylation at concentrations up to 100 nM, which at least in the case of 25-49 and 83-14 was sufficient for full receptor occupancy. It is concluded that the insulin-like metabolic effects of antibodies involve a mechanism of receptor activation that is independent of autophosphorylation and hence that receptor autophosphorylation is not an essential step in triggering at least some events in the insulin signaling pathway.

Analysis of insulin-receptor phosphorylation sites in intact cells by two-dimensional phosphopeptide mapping

Insulin stimulates the autophosphorylation of the partially purified insulin receptor initially on tyrosine residues 1146, 1150 and 1151. This is followed by increased autophosphorylation of tyrosine residues 1316, 1322 and two further residues, possibly tyrosine residues 953 and 960 or 972 [Tavaré & Denton (1988) Biochem. J. 252, 607-615]. In the present paper we have used two cell lines transfected with insulin-receptor cDNA (CHO.T and NIH 3T3 HIR3.5 cells) to assess which tyrosine residues are phosphorylated on the insulin receptor within intact cells. We show that: (1) insulin causes a rapid increase in phosphorylation of tyrosine residues 1146, 1150 and 1151 in both cell types; tyrosine residues 1316 and 1322 are also phosphorylated, but apparently to a lesser extent in NIH 3T3 HIR3.5 cells; (2) the sites that may correspond to tyrosine residues 953 and 960 or 972 appear to be very poorly phosphorylated in both intact cell types; (3) insulin also promotes a substantial and rapid increase in the phosphorylation of serine and threonine residues on insulin receptors on CHO.T cells; this results in the appearance of two phosphopeptides not evident in the maps of the solubilized receptor preparations autophosphorylated in vitro.

Monoclonal antibodies to the insulin receptor stimulate the intrinsic tyrosine kinase activity by cross-linking receptor molecules

The effect of monoclonal anti-insulin receptor antibodies on the intrinsic kinase activity of solubilized receptor was investigated. Antibodies for six distinct epitopes stimulated receptor autophosphorylation and kinase activity towards exogenous substrates. This effect of antibodies was seen only within a narrow concentration range and monovalent antibody fragments were ineffective. Evidence was obtained by sucrose density-gradient centrifugation for the formation of antibody-receptor complexes which involved both inter- and intra-molecular cross-linking, although stimulation of autophosphorylation appeared to be preferentially associated with the latter. There was partial additivity between the effects of insulin and antibodies in stimulating autophosphorylation, although the sites of phosphorylation appeared identical on two-dimensional peptide maps. Antibodies for two further epitopes failed to activate receptor kinase, but inhibited its stimulation by insulin. The effects of antibodies on kinase activity paralleled their metabolic effects on adipocytes, except for one antibody which was potently insulin-like in its metabolic effects, but which antagonized insulin stimulation of kinase activity. It is concluded that antibodies activate the receptor by cross-linking subunits rather than by reacting at specific epitopes. The ability of some antibodies to activate receptor may depend on receptor environment as well as the disposition of epitopes.

Interaction of the human insulin receptor with the ras oncogene product p21

Autophosphorylation of the purified human insulin receptor tyrosyl kinase was found to be inhibited by the ras oncogene product p21 in a concentration- and GDP-dependent manner. GDP-beta-S but not Gpp(NH)p could substitute for GDP in eliciting the ras-dependent inhibition. The inhibition was seen with both normal or mutant (Lys-61) p21N-ras and normal or mutant (Val-12) p21Ha-ras. Inhibition occurred at 23 degrees C but not 4 degrees C and was unaffected by the presence or absence of insulin although insulin stimulated the autophosphorylation rate of the receptor beta-subunit some 2-fold. The insulin receptor did not phosphorylate native p21Ha-ras in the presence or absence of added guanine nucleotide. After denaturation of p21Ha-ras with urea it became a substrate, but then failed to inhibit receptor autophosphorylation even in the presence of added GDP.

The insulin receptor tyrosyl kinase phosphorylates holomeric forms of the guanine nucleotide regulatory proteins Gi and Go

An affinity purified human insulin receptor preparation was shown to phosphorylate the alpha- and beta-subunits of the guanine nucleotide-regulatory proteins Gi and Go, derived from bovine brain. The presence of insulin stimulated the rate of their phosphorylation some 2-fold. The presence of Gi and Go did not affect the degree of autophosphorylation of the beta-subunit of the insulin receptor. Under conditions known to cause the dissociation of Gi and Go into their constituent subunits then phosphorylation of Gi and Go by the insulin receptor was abolished. The alpha-subunits of Gi and Go could be selectively phosphorylated by the insulin receptor tyrosyl kinase using appropriate concentrations of Mg2+ and GTP-gamma-S.

Self-efficacy and self-motivation as predictors of weight loss

The present study was attempted to determine whether self-efficacy and self-motivation would predict outcome in an intensive weight loss program. The subjects included 52 males and 95 females who were at least fifty pounds overweight (mean age = 43 years). The data were analyzed through multiple regression on three separate dependent variables: actual weight loss, adjusted weight loss and percentage of sessions attended. Outcome was predicted based on the following variables: self-efficacy (as measured by confidence estimates and outcome expectancies) and self-motivation (as measured by the Self-Motivation Inventory). The predictors accounted for 32.2% (p less than .01) of the variance in actual weight loss, 8.5% (p less than .01) of the variance in adjusted weight loss and none of the variance in percentage of sessions attended. Self-motivation did not correlate significantly with either actual or adjusted weight loss, while self-efficacy measures did. However, the correlation of the two self-efficacy measures (r = -.07, p greater than .05) suggests that these variables do not constitute a unitary construct and should be conceptualized as independent predictors. These findings suggest that confidence estimates and outcome expectancies are useful predictors of weight loss.

The effect of target behavior monitoring on weight loss and completion rate in a behavior modification program for weight reduction

Although behavior modification of obesity is usually described as a behavior change procedure, measurement is most often limited to the outcome variable of weight loss. The present investigation employed detailed behavior monitoring forms in half of 16 obesity groups (n = 173) matched across four different therapists. The percentage of compliance for nine specific treatment behaviors was charted from these monitoring forms. At the end of treatment, the eight groups that had the behavior monitoring treatment averaged over 6 pounds more weight lost than the matched control groups as well as showing significantly better attendance. The between group weight loss differences were still evident 3 months after treatment.

Urban structure and household victimization of the elderly

This paper examines the relationships of several urban structural characteristics with the rate of household victimization of the elderly in twenty-six U.S. central cities. We find that inter-city variation in two types of household victimization (household burglary and larcency) is highly related to two factors: 1) population density, and 2) socioeconomic conditions. The implications of these findings for further research are discussed.

Effects of cash deposits on attendance and weight loss in a large-scale clinical program for obesity

The effects of a cash deposit for attendance were examined in 579 clients at a fee for service obesity clinic. The weight loss and attendance of 26 groups required to submit a refundable attendance deposit were compared to 34 no-deposit groups. Significant differences in weight loss and attendance favored those groups who submitted refundable deposits.

Worksite-based behavioral treatment of mild hypertension

Two behaviorally-oriented, nonpharmacological treatments - rational-emotive therapy/assertiveness training (RET/AT) and anxiety management training (AMT) - and one control treatment - hypertension education counseling (HEC) - were compared in reducing blood pressures of 22 white-collar mold hypertensives in a worksite setting. Results showed significant reductions by posttreatment in diastolic pressures of participants in the two behavioral treatment conditions, but no significant differential treatment effect across groups. Systolic pressure reductions by postreatment were significant only in the RET/AT training condition. Reductions were generally maintained at an either-week follow-up.

Behavior therapy and pharmacotherapy for obesity

The effects of behavior therapy, pharmacotherapy, and their combination were compared in 120 women during six months of treatment of obesity and one year after treatment. Patients who received fenfluramine hydrochloride alone lost 14.5 kg, ad those who had combined pharmacotherapy and behavior therapy lost 15.3 kg; both losses were significantly greater than that of those who had behavior therapy alone (10.9 kg). A waiting-list control group gained 1.3 kg. One-year follow-up of all living patients who completed treatment showed a striking reversal in the relative efficacy of the treatments. Behavior-therapy patients regained significantly less than pharmacotherapy and combined-treatment patients. Accordingly, at follow-up, these groups did not differ significantly in weight loss. Thus, pharmacotherapy produced more rapid regaining of weight after treatment. Furthermore, adding pharmacotherapy to behavior therapy apparently compromised the long-term effects of the latter treatment.

Treatment of anxiety about college tests with negative practice and systematic desensitization: some negative findings

72 test-anxious subjects were assigned to three treatment groups and two control groups for 6 weekly sessions. Treatment conditions were negative practice with and without homework instructions and systematic desensitization. The two control conditions involved a psychoanalytically oriented attention-placebo group and a waiting-list, no-treatment group. There were no differences in grade point average between groups following treatment. Only the group given systematic desensitization showed improvement in self-reported test anxiety. These negative results are discussed in comparison to earlier findings. The need for measures of behavioral outcome is emphasized.

Immediate auditory feedback to improve putting quickly

After being baserated for three putts from each of three distances, six veteran golfers were given immediate feedback for head and body movement in a brief treatment session. Providing immediate feedback of the inappropriate movement resulted in a statistically significant increase in the number of putts holed.

Contingency factors in negative practice of smoking

100 cigarette smokers were randomly assigned to 1 of 5 treatment groups balancing the level of smokers within groups. To uncover the importance of chaining in overresponding or satiation treatments of cigarette smoking, 2 of these groups were required to double or triple their baserate in 2 or 3 cigarette chains while a third group simply doubled their daily consumption. For comparison, a fourth group received covert sensitization treatment of their smoking while a fifth group acted as an attention-monitoring control. Following 1 wk. of cigarette-by-cigarette baserate each group received 1 wk. of treatment and 3 wk. of follow-up meetings. Contacts with all subjects were also made 3 and 6 mo. after treatment. All groups significantly decreased smoking following treatment, but the 3-mo. follow-up showed no significant difference from baserate. Group differences were not statistically significant, although the attention-monitoring group was least effective at all posttreatment measurement points. Although subject reports indicate chaining increased the aversiveness of the negative practice regime, it showed no effect on treatment efficiency.

Negative practice and desensitization of anxiety about examinations

30 test-anxious subjects were assigned to two treatment groups for 6 weekly sessions. One group experienced standard group-desensitization of test anxiety while the other group was instructed in negative practice of anxiety responses and satiation of anxiety-producing stimuli. There were no significant differences between the two treatment groups and a control group ( N = 15) in grades for the semester preceding treatment. Both treatment groups had significantly higher grades than the control group following treatment. Given negative practice, one group obtained significantly higher grades than the desensitized group. Both treatment groups reported a significant decrease in test anxiety but no such difference was reported by a second control group. It is suggested that both negative practice and desensitization might be effective intervention strategies for test anxiety.