Conformational control in the population of the triplet state and photoreactivity of nitronaphthalene derivatives.

Nitronaphthalene derivatives (NNDs) are among the most abundant volatile nitro-polycyclic aromatic hydrocarbons found in the Earth's atmosphere. Investigations of the atmospheric degradation processes show that photolysis is the major degradation pathway under ambient conditions. In this contribution, we present photochemical measurements and quantum-chemical calculations of three major NNDs. It is shown that the magnitude of the photodegradation and triplet quantum yields in 1-nitronaphthalene (1NN), 2-methyl-1-nitronaphthalene (2M1NN), and 2-nitronaphthalene (2NN) are inversely related to each other. In accord with a recent time-resolved and computation study (J. Phys. Chem. A 2013, 117, 6580) and in order to explain this striking observation we propose that these photochemical yields are largely controlled by (1) the conformational heterogeneity of the nitro-aromatic torsion angle, (2) the energy gap (spin-orbit coupling interaction) between the excited singlet state and the receiver triplet state, and (3) the topology of the excited singlet state in the Franck-Condon region of configuration space sampled at the time of excitation. A distribution of torsion angles closer to 90° leads to a higher photoreactivity. Methylation of the ortho position in 1NN to give 2M1NN increases the photoreactivity by 97%, while 2NN is largely photoinert. Conversely, the triplet yield decreases as the distribution of torsion angles gets closer to 90°: 0.93 ± 0.15 in 2NN, 0.64 ± 0.12 in 1NN, and 0.33 ± 0.05 in 2M1NN. These results suggest an important relationship between conformational heterogeneity and the photochemical fate of these NNDs. This structure-photoreactivity relationship is of relevance to current efforts aimed at modeling and understanding the distribution patterns of NNDs in the atmosphere and their overall contribution to air quality.

Changes in resting energy expenditure after weight loss in obese African American and white women.

BACKGROUND: Previous studies showed that resting energy expenditure (REE) is lower in obese African American women than in obese white women. It is unknown, however, whether there are racial differences in how REE responds to weight loss and energy restriction. OBJECTIVE: We assessed REE, body composition, and respiratory quotient before and after weight loss in obese black and white women. DESIGN: We measured REE by indirect calorimetry and body composition by densitometry before and after 20-24 wk of treatment with a 3870-4289-kJ/d diet. Subjects were 109 obese females (24 black, 85 white) with a mean (+/-SD) body mass index (in kg/m2) of 36.3+/-5.0, weight of 95.7+/-12.6 kg, and age of 42.3+/-8.1 y. RESULTS: Before treatment, REE, adjusted for body composition, was significantly lower in black than in white subjects (P = 0.001). Black subjects lost significantly less weight during treatment than did white subjects (13.4+/-5.9 kg or 14.2+/-5.7% compared with 16.4+/-5.6 kg or 17.0+/-5.7%, respectively; P = 0.04). Analyses that controlled for initial REE and changes in fat mass and fat-free mass showed that blacks had significantly greater decreases in REE after treatment than did whites (9.9+/-7.3% compared with 6.3+/-7.4%; P = 0.02). CONCLUSION: This study suggests that weight loss results in greater reductions in REE in obese black women than in obese white women. These data underscore the need to consider both biological and behavioral factors when setting expectations and assessing outcomes for obesity treatment in African American women.

The Eating Inventory in obese women: clinical correlates and relationship to weight loss.

OBJECTIVES: Describe the physical and psychological correlates of the Eating Inventory (EI) (also known as the Three-Factor Eating Questionnaire) factors in an obese sample, and determine the relationship between the three EI factors and weight loss. DESIGN: Consecutive series of obese women enrolled between 1987 and 1996 in clinical trials of weight loss treatments. PARTICIPANTS: 223 obese women with a weight of 100.7 +/- 15.5 kg, an age of 41.4 +/- 8.8 y and a body mass index (BMI) of 37.2 +/- 5.6 kg/m2. MEASURES: The EI and a variety of physical (weight, body composition and resting energy expenditure) and psychological (mood and binge eating) measures were assessed before and after 5-6 months of treatment. RESULTS: Before treatment, higher restraint scores were associated with lower body weights (P = 0.02), while higher disinhibition scores were associated with greater binge eating severity (P<0.0001). Weight loss treatment was associated with significant increases in restraint and decreases in disinhibition and hunger (all Ps<0.0001). Greater increases in restraint during treatment were associated with larger weight losses (P<0.0001). CONCLUSIONS: The three factors of the EI showed clinical utility in a sample of women receiving treatment for obesity.

The fen-phen finale: a study of weight loss and valvular heart disease.

OBJECTIVE: To assess weight loss, as well as the prevalence of valvular heart disease, in 21 obese women who completed 2 years of treatment by fenfluramine and phentermine (fen-phen) in June 1997. RESEARCH METHODS AND PROCEDURES: Patients were 21 of 22 women who had completed a 1-year, open-label trial of fen-phen combined with lifestyle modification. This study describes the results of a second year of treatment. The presence of valvular heart disease, defined as aortic regurgitation of mild or greater severity and/or mitral regurgitation of moderate or greater severity, was assessed using two-dimensional, color Doppler and pulsed- and continuous-wave Doppler examinations. RESULTS: At 2 years, the 21 patients had a mean reduction in initial weight of 13.9 + 10.0%, which was significantly (p<0.001) smaller than their 1-year loss of 17.1 +/- 8.7%. Nine of 21 patients reported that they took fen-phen irregularly during the last 4 months of the study because of fears of developing health complications. These nine patients had a 2-year weight loss of 8.7 +/- 7.5%, compared with a significantly (p<0.04) larger loss of 17.6 +/- 10.5% for participants who reported taking medication regularly. Six of 20 (30%) patients met criteria for valvular heart disease. None of the six had signs or symptoms of this condition. DISCUSSION: Fenfluramine was withdrawn from the market on September 15, 1997 because of concerns that it was associated with valvular heart disease. The present findings are discussed in terms of the potentially favorable long-term benefits of combining lifestyle modification with weight loss medications that are both safe and effective.

Exercise and the maintenance of weight loss: 1-year follow-up of a controlled clinical trial.

This study reports results 1 year after treatment for 77 obese women who had been treated for 48 weeks by diet combined with supervised (a) aerobic exercise, (b) strength training, (c) aerobic plus strength training combined, or (d) no exercise. Mean (+/- SD) end-of-treatment weight losses for the 4 conditions ranged from 13.5 +/- 9.1 kg to 17.3 +/- 10.3 kg, but there were no statistically significant differences among groups. Participants in all 4 conditions regained approximately 35% to 55% of their weight loss in the year after treatment; again, there were no significant differences among groups. Participants, however, who reported exercising regularly in the 4 months preceding the follow-up assessment regained significantly less weight than did nonexercisers.

A comparison of two approaches to the assessment of binge eating in obesity.

OBJECTIVE: To compare two different methods of assessing binge eating in a sample of 128 obese women enrolled in a weight loss protocol. METHOD: Prior to treatment, participants completed the Binge Eating Scale (BES) and the Questionnaire on Eating and Weight Patterns (QEWP), as well as measures of other relevant constructs. They were then classified as bingers and nonbingers by each method and chance-corrected agreement was calculated. RESULTS: The BES and QEWP identified a small and nearly equal number of subjects as having significant binge eating, but there was only modest overlap between the two groups (kappa of .45). Subgroup comparisons revealed fundamental differences between the BES and QEWP in the assessment of the critical and associated features of binge eating. DISCUSSION: The relative merits of these two approaches to classifying binge eaters and implications for the design of new methods are discussed.

Lifestyle modification in the pharmacologic treatment of obesity: a pilot investigation of a potential primary care approach.

This study examined a new method of providing brief, individual lifestyle modification to obese individuals treated by pharmacotherapy. Twenty-six women with a mean (+/- SD) age of 47.0 +/- 7.2 years, weight of 97.6 +/- 13.0 kg, and body mass index of 36.5 +/- 5.0 kg/m2 were prescribed 60 mg/d of fenfluramine and 15 mg/d of phentermine for one year. In addition, half of the women were randomly assigned to traditional group behavior modification, conducted by a nutritionist, which included 32 75-minute sessions during the year. The other half were provided lifestyle modification by a physician during 10 15-20 minute structured visits. All participants received identical treatment manuals and comparable assignments for behavior change. At the end of one year, patients in the physician group achieved the same highly successful weight losses as those treated by group behavior modification (13.9 +/- 9.6 kg vs. 15.4 +/- 7.9 kg, respectively). Treatment was associated with highly significant improvements in lipids and lipoproteins, as well as in mood and several measures of appetite. Weight loss the first four weeks, as well as patient completion of daily food records during the first 18 weeks, correlated positively with weight loss at weeks 18, 26, and 52. Results of this study await replication using larger samples but strongly suggest that effective lifestyle modification can be provided during brief, structured physician visits. The findings are discussed in terms of their implications for the treatment of obesity in primary care practice.

Body image in obese women before, during, and after weight loss treatment.

Body image, as measured by the Appearance Evaluation and Body Areas Satisfaction scales of the Multidimensional Body-Self Relations Questionnaire (T.F. Cash, 1994b), was assessed in 59 obese women before, during, and after 48 weeks of weight loss treatment. Before treatment, positive ratings of body image were associated with higher levels of self-esteem, lower levels of dysphoria, and fewer previous diets. After 24 weeks and a mean weight loss of 19.4 kg (SD = 6.5), participants showed significant (p < .0001) improvements in body image. A small weight gain from Week 24 to Week 48 was associated with a slight but significant worsening in both measures of body image. Nevertheless, after 48 weeks and a mean weight loss of 16.3 kg (SD = 7.1), body image was significantly improved from baseline (p < .0001). Changes in body image were not related to changes in weight. Future studies are needed to separate the effects of treatment and weight loss on body image in obese persons.

Exercise in the treatment of obesity: effects of four interventions on body composition, resting energy expenditure, appetite, and mood.

This study investigated changes in body composition, resting energy expenditure (REE), appetite, and mood in 128 obese women who were randomly assigned to 1 of 4 treatment conditions: diet alone, diet plus aerobic training, diet plus strength training, or diet combined with aerobic and strength training (i.e., combined training). All women received the same 48-week group behavioral program and were prescribed the same diet. Exercising participants were provided 3 supervised exercise sessions per week for the first 28 weeks and 2 sessions weekly thereafter. Participants across the 4 conditions achieved a mean weight loss of 16.5 +/- 6.8 kg at Week 24, which decreased to 15.1 +/- 8.4 kg at Week 48. There were no significant differences among conditions at any time in changes in weight or body composition. Women who received aerobic training displayed significantly smaller reductions in REE at Week 24 than did those who received strength training. There were no other significant differences among conditions at any time on this variable or in changes in appetite and mood.

What is a reasonable weight loss? Patients' expectations and evaluations of obesity treatment outcomes.

Expert panels and governmental guidelines now recommend that obese persons seek modest (i.e., "reasonable") reductions in body weight rather than striving for "ideal" weights. Little is known, however, about patients' views of what is a "reasonable" weight loss. This study assessed patients' goals, expectations, and evaluations of various outcomes before, during, and after 48 weeks of treatment. Before treatment, 60 obese women (99.1 +/- 12.3 kg; body mass index of 36.3 +/- 4.3 kg/ m2) defined their goal weight and 4 other weights: "dream weight"; "happy weight"; "acceptable weight"; and "disappointed weight." Goal weight averaged a 32% reduction in body weight. A 17-kg weight loss was defined as disappointed; a 25-kg loss, was acceptable. After 48 weeks of treatment and a 16-kg weight loss, 47% of patients did not achieve even a disappointed weight. These data illustrate the dramatic disparity between patients' expectations and professional recommendations and the need to help patients accept more modest weight loss outcomes.

Resting energy expenditure in obese African American and Caucasian women.

The prevalence of obesity among African American women approaches 50% and greatly exceeds rates for Caucasian women. In addition, black women lose less weight than white during obesity treatment and gain more weight when untreated. This study assessed resting energy expenditure (REE) and body composition in obese white (n = 122) and black (n = 44) women to explore the relationship between biological variables and these observed differences. REE and body composition were assessed by indirect calorimetry and densitometry, respectively, before weight loss. REE was significantly lower in black subjects (1637.6 +/- 236.9 kcal/d) than in white (1731.4 +/- 262.0) (p = 0.04). REE remained significantly lower in blacks than whites after adjusting for body weight (p = 0.02). REE, adjusted for fat-free mass, was also significantly lower in blacks than whites (p < 0.0001), although the overestimation of fat-free mass by densitometry in blacks may have contributed to this finding. There were no differences between the groups in respiratory quotient. These results suggest that a decreased REE may exist in obese black women, and it may be related to the observed differences between black and white women in the prevalence of obesity and in the response to weight loss treatment. These cross-sectional findings await confirmation in longitudinal studies.

Psychological effects of weight loss and regain: a prospective evaluation.

This study prospectively assessed the psychological effects of weight loss and regain (i.e., weight cycling) in obese women. Measures of mood, binge eating, restraint, disinhibition, and hunger were obtained from 55 participants at baseline, after 6 months of treatment, and 58 months posttreatment. Women lost 21.1 +/- 8.4 kg after 6 months of treatment but were 3.6 +/- 10.9 kg above baseline weight at the time of the follow-up. Contrary to expectations, after this 21-kg cycle of weight loss and regain, women reported significant improvements in mood and binge eating, as well as reductions in hunger and disinhibition. Restraint was unchanged from baseline to follow-up. These data suggest that weight loss and regain are not associated with long-term adverse psychological effects. The findings also confirm earlier reports of significant weight regain after treatment and underscore the need for research to improve the maintenance of weight loss.

Psychosocial consequences of weight cycling.

Participants were 130 obese women with a mean age of 41.1 +/- 8.4 years and a mean weight of 97.9 +/- 13.5 kg, who reported having undertaken a mean lifetime total of 4.7 +/- 1.2 major diets on which they had lost a mean total of 45.9 +/- 21.4 kg. Participants with a severe history of weight cycling had a significantly younger age of onset of their obesity than did mild cyclers and reported initiating dieting at a significantly younger age and lower weight. No evidence, however, was found that weight cycling was associated with greater reports of depression or other psychopathology; nor was it associated with a significantly greater frequency of binge eating disorder. The results are discussed in terms of the need to use additional measures of psychological functioning.

Relation of weight loss to changes in serum lipids and lipoproteins in obese women.

Several reports have suggested that modest weight losses, as little as 10% of initial weight, are sufficient to control many of the health complications of obesity. This study examined the relation between changes in weight and those in serum lipids and lipoproteins in obese women who participated in a 48-wk weight-reduction study. Subjects were 66 obese women who were prescribed a 3870-kJ (925-kcal)/d diet for the first 16 wk and a balanced-deficit diet of 5029-6279 kJ (1200-1500 kcal)/d thereafter. Anthropometric measures were assessed at baseline and weeks 8, 24, and 48, as were serum triacylglycerols (triglycerides), total cholesterol, and low-density-lipoprotein- and high-density-lipoprotein-cholesterol concentrations. Weight decreased 11.1% during the first 8 wk, during which time triacylglycerols and total cholesterol fell 22.7% and 15.7%, respectively. Subjects lost an additional 4.7 kg (equal to a total reduction of 16.4%) between weeks 8 and 24 but triacylglycerols and total and low-density-lipoprotein cholesterol increased by 5.2%, 4.2%, and 4.5%, respectively during this time. Multiple-regression analyses showed that at no time did weight loss account for > 6% of the variance in the reductions in triacylglycerol and cholesterol concentrations. These findings indicate that modest weight losses are associated with significant improvements in serum lipids, but that factors including the energy and macronutrient content of the diet prescribed contribute significantly to the improvements observed.

Enzymatic fragmentation of an unusual human IgG2 (Kva) myeloma protein.

The Kva IgG2(k) myeloma protein showed a complete resistance to papain in the presence of cysteine at neutral pH, and a higher resistance to trypsin and alpha-chymotrypsin digestion than other IgG2 proteins. On the other hand, the Kva molecule was cleaved by pepsin at low pH to give the expected F(ab')2 fragment. When the cleavage conditions were altered, it was possible to obtain Fab, Fc, and Fc' fragments from this molecule as well. The Fab/c fragment and FacbFc' complex were also obtained, which have not previously been reported from human IgG2 molecules. Incubation at elevated temperatures (45-50 degrees C) and/or lower pH resulted mainly in enzymatic attack on the C terminal side of the hinge. It was necessary to destroy the hinge by reduction or to expose the Kva molecule at 70 degrees C or at lower pH (2.5) prior to digestion to facilitate enzyme digestion on the NH2 terminal side of the hinge. These results indicate that the hinge region of the Kva molecule has an unusually compact structure, which makes it extremely resistant to proteolysis.