Characterizing osmolyte chemical class hierarchies and functional group requirements for thermal stabilization of proteins.

Osmolytes are naturally occurring organic compounds that protect cellular proteins and other macromolecules against various forms of stress including temperature extremes. While biological studies have correlated the accumulation of certain classes of osmolytes with specific forms of stress, including thermal stress, it remains unclear whether or not these observations reflect an intrinsic chemical class hierarchy amongst the osmolytes with respect to effects on protein stability. In addition, very little is known in regards to the molecular elements of the osmolytes themselves that are essential for their functions. In this study, we use differential scanning fluorimetry to quantify the thermal stabilizing effects of members from each of the three main classes of protecting osmolytes on two model protein systems, C-reactive protein and tumor necrosis factor alpha. Our data reveals the absence of a strict chemical class hierarchy amongst the osmolytes with respect to protein thermal stabilization, and indicates differential responses of these proteins to certain osmolytes. In the second part of this investigation we dissected the molecular elements of amino acid osmolytes required for thermal stabilization of myoglobin and C-reactive protein. We show that the complete amino acid zwitterion is required for thermal stabilization of myoglobin, whereas removal of the osmolyte amino group does not diminish stabilizing effects on C-reactive protein. These disparate responses of proteins to osmolytes and other small molecules are consistent with previous observations that osmolyte effects on protein stability are protein-specific. Moreover, the data reported in this study support the view that osmolyte effects cannot be fully explained by considering only the solvent accessibility of the polypeptide backbone in the native and denatured states, and corroborate the need for more complex models that take into account the entire protein fabric.

New limits on variation of the fine-structure constant using atomic dysprosium.

We report on the spectroscopy of radio-frequency transitions between nearly degenerate, opposite-parity excited states in atomic dysprosium (Dy). Theoretical calculations predict that these states are very sensitive to variation of the fine-structure constant α owing to large relativistic corrections of opposite sign for the opposite-parity levels. The near degeneracy reduces the relative precision necessary to place constraints on variation of α, competitive with results obtained from the best atomic clocks in the world. Additionally, the existence of several abundant isotopes of Dy allows isotopic comparisons that suppress common-mode systematic errors. The frequencies of the 754-MHz transition in 164Dy and 235-MHz transition in 162Dy are measured over the span of two years. The linear variation of α is α·/α=(-5.8±6.9([1σ]))×10(-17) yr(-1), consistent with zero. The same data are used to constrain the dimensionless parameter kα characterizing a possible coupling of α to a changing gravitational potential. We find that kα=(-5.5±5.2([1σ]))×10(-7), essentially consistent with zero and the best constraint to date.

Constraining the evolution of the fundamental constants with a solid-state optical frequency reference based on the 229Th nucleus.

We describe a novel approach to directly measure the energy of the narrow, low-lying isomeric state in 229Th. Since nuclear transitions are far less sensitive to environmental conditions than atomic transitions, we argue that the 229Th optical nuclear transition may be driven inside a host crystal with a high transition Q. This technique might also allow for the construction of a solid-state optical frequency reference that surpasses the short-term stability of current optical clocks, as well as improved limits on the variability of fundamental constants. Based on analysis of the crystal lattice environment, we argue that a precision (short-term stability) of 3×10(-17)<Δf/f<1×10(-15) after 1 s of photon collection may be achieved with a systematic-limited accuracy (long-term stability) of Δf/f∼2×10(-16). Improvement by 10(2)-10(3) of the constraints on the variability of several important fundamental constants also appears possible.

Extended temperature tuning of an ultraviolet diode laser for trapping and cooling single Yb+ ions.

We describe an ultraviolet (uv) diode laser system for cooling trapped Yb(+) ions. Using four stages of thermoelectric cooling, 10 mW of light at 369.5 nm is obtained by cooling a 373.4-nm uv diode to approximately -20 degrees C. Frequency stabilization is provided by a diffraction grating mounted in the Littrow configuration which allows for a mode-hop free tuning range of approximately 25 GHz. In order to avoid water condensation, the diode laser and associated optics are placed inside an evacuated chamber. Saturated absorption spectroscopy utilizing an Yb hollow cathode lamp is performed. This laser system is currently being used to cool single ions in an experiment whose ultimate goal is to look for modern variation of the fine-structure constant.

Should snacks be recommended in obesity treatment? A 1-year randomized clinical trial.

OBJECTIVE: To study the effect to recommend no snacks vs three snacks per day on 1-year weight loss. The hypothesis was that it is easier to control energy intake and lose weight if snacks in between meals are omitted. SUBJECTS/METHOD: In total 140 patients (36 men, 104 women), aged 18-60 years and body mass index>30 kg/m(2) were randomized and 93 patients (27 men, 66 women) completed the study. A 1-year randomized intervention trial was conducted with two treatment arms with different eating frequencies; 3 meals/day (3M) or 3 meals and 3 snacks/day (3+3M). The patients received regular and individualized counseling by dieticians. Information on eating patterns, dietary intake, weight and metabolic variables was collected at baseline and after 1 year. RESULTS: Over 1 year the 3M group reported a decrease in the number of snacks whereas the 3+3M group reported an increase (-1.1 vs +0.4 snacks/day, respectively, P<0.0001). Both groups decreased energy intake and E% (energy percent) fat and increased E% protein and fiber intake but there was no differences between the groups. Both groups lost weight, but there was no significant difference in weight loss after 1 year of treatment (3M vs 3+3M=-4.1+/-6.1 vs -5.9+/-9.4 kg; P=0.31). Changes in metabolic variables did not differ between the groups, except for high-density lipoprotein that increased in the 3M group but not in 3+3M group (P<0.033 for group difference). CONCLUSION: Recommending snacks or not between meals does not influence 1-year weight loss.

Limit on the temporal variation of the fine-structure constant using atomic dysprosium.

Over 8 months, we monitored transition frequencies between nearly degenerate, opposite-parity levels in two isotopes of atomic dysprosium (Dy). These frequencies are sensitive to variation of the fine-structure constant (alpha) due to relativistic corrections of opposite sign for the opposite-parity levels. In this unique system, in contrast to atomic-clock comparisons, the difference of the electronic energies of the opposite-parity levels can be monitored directly utilizing a rf electric-dipole transition between them. Our measurements show that the frequency variation of the 3.1-MHz transition in (163)Dy and the 235-MHz transition in (162)Dy are 9.0+/-6.7 Hz/yr and -0.6+/-6.5 Hz/yr, respectively. These results provide a rate of fractional variation of alpha of (-2.7+/-2.6) x 10(-15) yr(-1) (1 sigma) without assumptions on constancy of other fundamental constants, indicating absence of significant variation at the present level of sensitivity.

Snacking frequency in relation to energy intake and food choices in obese men and women compared to a reference population.

OBJECTIVE: To investigate snacking frequency in relation to energy intake and food choices, taking physical activity into account, in obese vs reference men and women. DESIGN: Cross-sectional, descriptive study. SUBJECTS: In total, 4259 obese, middle-aged subjects (1891 men and 2368 women) from the baseline examination of the XENDOS study and 1092 subjects (505 men and 587 women) from the SOS reference study were included. MEASUREMENTS: A meal pattern questionnaire describing habitual intake occasions (main meals, light meals/breakfast, snacks, drink-only), a dietary questionnaire describing habitual energy and macronutrient intake and a questionnaire assessing physical activity at work and during leisure time were used. RESULTS: The obese group consumed snacks more frequently compared to the reference group (P<0.001) and women more frequently than men (P<0.001). Energy intake increased with increasing snacking frequency, irrespective of physical activity. Statistically significant differences in trends were found for cakes/cookies, candies/chocolate and desserts for the relation between energy intake and snacking frequency, where energy intake increased more by snacking frequency in obese subjects than in reference subjects. CONCLUSION: Obese subjects were more frequent snackers than reference subjects and women were more frequent snackers than men. Snacks were positively related to energy intake, irrespective of physical activity. Sweet, fatty food groups were associated with snacking and contributed considerably to energy intake. Snacking needs to be considered in obesity treatment, prevention and general dietary recommendations.

Low-frequency character of the Casimir force between metallic films.

The frequency spectrum of the finite temperature correction to the Casimir force can be determined by use of the Lifshitz formalism for metallic plates of finite conductivity. We show that the correction for the TE electromagnetic modes is dominated by frequencies so low that the plates cannot be modeled as ideal dielectrics. We also address issues relating to the behavior of electromagnetic fields at the surfaces and within metallic conductors, and calculate the surface modes using appropriate low-frequency metallic boundary conditions. Our result brings the thermal correction into agreement with experimental results that were previously obtained. We suggest a series of measurements that will test the veracity of our analysis.

A comparative controlled study of personality in severe obesity: a 2-y follow-up after intervention.

OBJECTIVE: The primary purpose was to examine 2-y effects of weight change on personality traits in severely obese subjects treated conventionally or surgically. We also assessed differences between the severely obese patients and a primarily normal-weight reference group. METHOD: Personality traits were assessed using 7 of 15 scales from the Karolinska Scales of Personality (KSP): Somatic Anxiety, Muscular Tension, Psychasthenia, Psychic Anxiety, Monotony Avoidance, Impulsiveness, and Irritability. A total of 1380 surgical candidates, 1241 conventionally treated patients and 1135 subjects from the SOS (Swedish Obese Subjects) reference study, representing the general population, completed the KSP. Data presented in this study were gathered twice from the patients (prior to treatment and after 2 y) and once from the reference subjects. Significance tests and effect sizes (ES) were calculated. RESULTS: At baseline, the obese were characterised as more anxiety prone, impulsive, irritable and less monotony avoiding than the reference group; surgery patients more so than the conventionally treated. At follow-up, it was found that anxiety proneness decreased and Monotony Avoidance increased with increasing weight loss. The conventionally treated were, on average, weight stable and, hence, only a small decrease was noted regarding Somatic Anxiety. The surgery group lost on average 28 kg, and differences between surgically treated and the reference group decreased on all scales except Impulsiveness, which remained unchanged. The largest improvement was in relation to Psychasthenia. CONCLUSIONS: Weight reduction maintained for 2 y was associated with changes on practically all personality traits in proportion to the magnitude of weight loss. In particular, Psychasthenia seemed to be alleviated, while Impulsiveness was unaffected.

Severe obesity and personality: a comparative controlled study of personality traits.

OBJECTIVE: The primary purpose was to assess personality trait differences between the severely obese seeking treatment and a mainly non-obese reference group. We also investigated gender differences and differences between obese patients and obese not seeking treatment. METHOD: Personality traits were assessed using 7 of 15 scales from the Karolinska Scales of Personality (KSP): Somatic Anxiety, Muscular Tension, Psychastenia, Psychic Anxiety, Monotony Avoidance, Impulsiveness, and Irritability. Patients from the Swedish Obese Subjects (SOS) intervention study (n=3270, ages 37-57, 71% women) and the SOS reference study (n=1135, 54% women) completed the survey. Data presented in this study were gathered prior to treatment. Significance tests and effects sizes were calculated. RESULTS: Although statistically significant differences were found between obese patients and reference subjects on nearly all personality traits, effect sizes were at most moderate. Of the three scales with moderate effects sizes, differences on Somatic Anxiety and Psychastenia could be traced to items tapping condition-specific symptoms, e.g., problems with sweating and breathing as indicators of Somatic Anxiety. Moderate differences on the Impulsiveness scale (men alone) could not be explained by item composition. Further, the obese patients differed from obese in the reference group, and both obese and reference women reported significantly higher levels on Somatic Anxiety, Muscular Tension and Psychic Anxiety compared to men (effect size: small). CONCLUSIONS: Our results provided no evidence of a general obese personality profile, instead considerable heterogeneity in personality traits was observed across our obese samples (treatment seekers vs non-seekers, men vs women) and generally only small differences were noted compared to a reference study population. Further research is needed to investigate if the somewhat elevated levels of Impulsiveness, particularly among male obese patients, is affected by weight loss. When assessing personality traits in diseased groups consideration should be given to possible confounding from, e.g., somatic symptoms.

Psychosocial functioning in the obese before and after weight reduction: construct validity and responsiveness of the Obesity-related Problems scale.

OBJECTIVE: The Obesity-related Problems scale (OP) is a self-assessment module developed to measure the impacts of obesity on psychosocial functioning. Our principal aim was to evaluate the construct validity and responsiveness of the OP scale. Our specific aims were to test: (1). the psychometric performance of OP; (2). if OP scores differed by gender and weight category; (3). if OP scores are inversely related to mental well-being; (4). if weight reduction in the obese is accompanied by improvements in psychosocial functioning (OP). SUBJECTS: Four samples were used: 6863 subjects in the SOS cross-sectional study; 2128 in the SOS intervention study; 1017 nonobese in the SOS reference study; and 3305 obese subjects in the XENDOS study. MEASUREMENTS: Psychosocial functioning was measured by OP. Overall mood was measured by MACL. Anxiety and depression symptoms were measured by HAD. RESULTS: Psychometric testing provided strong support for the construct validity of OP. Factor analysis confirmed the homogeneity of the construct and multitrait/multi-item scaling analysis demonstrated strong item-convergent/discriminant validity. Reliability coefficients were high and floor and ceiling effects were small. Psychometric results were cross-validated and replicated in subgroups by gender, age and body mass index (BMI). As expected, large differences in OP were observed between obese and nonobese (P<0.0001). Obese women reported more weight-related psychosocial problems than obese men (P<0.0001). Psychosocial disturbances (OP) among the obese were significantly related to poor mood (MACL; P<0.0001) and anxiety and depression symptoms (HAD; P<0.0001). Change in OP over time was strongly correlated with weight loss (P<0.0001). A distinct dose-response effect between weight reduction and improvements in OP was demonstrated. Scores on psychosocial functioning (OP) and mental well-being (MACL, HAD) in nonobese (BMI<30) surgical patients at 4-y follow-up were equal to scores observed in nonobese reference subjects (NS). CONCLUSION: OP is a psychometrically valid obesity-specific measure suitable for evaluating HRQL effects of obesity interventions. The negative impact of obesity on psychosocial functioning is considerable and disturbances are connected with poor mental well-being. Weight reduction in the obese is followed by improvements in both psychosocial functioning and mental well-being.

Intermittent versus on-demand use of a very low calorie diet: a randomized 2-year clinical trial.

OBJECTIVES: To compare two different very low calorie diet (VLCD)-based weight maintenance strategies. DESIGN AND SETTING: A randomized 2-year clinical trial performed at the Department of Body Composition and Metabolism, Sahlgrenska University Hospital, Sweden. SUBJECTS: A total of 334 patients, body mass index (BMI) >30 kg m-2, aged 18-60 years. INTERVENTIONS: All the patients started with 16 VLCD weeks. Subjects in the intermittent group were then scheduled to use VLCD for 2 weeks every third month, whilst patients in the on-demand group were instructed to use VLCD whenever their body weight passed an individualized cut-off level. Irrespective of the treatment group, all the subjects were recommended a hypocaloric diet during VLCD-free periods. MAIN OUTCOME MEASURES: Changes in body weight, body composition, anthropometric variables and cardiovascular risk factors. RESULTS: Completers in both groups maintained highly significant weight losses after 2 years: 7.0 +/- 11.0 kg (6.2 +/- 9.5%) in the intermittent group and 9.1 +/- 9.7 kg (7.7 +/- 8.1%) in the on-demand group (P < 0.001, ns between groups). Male completers in the on-demand group lost significantly more weight than men in the intermittent group, 14.5 +/- 11.0 kg vs. 4.0 +/- 10.5 kg, respectively (P < 0.01). Most cardiovascular risk factors improved during the first year, whilst anthropometric measures, insulin, HDL- and LDL-cholesterol were also significantly improved after 2 years of treatment. CONCLUSION: Clinically significant weight reductions were achieved after 2 years of VLCD-based treatment. The structure of VLCD treatment during the maintenance phase did not affect weight loss in the total study population, whilst male subjects might benefit from the VLCD on-demand strategy.

[The "Swedish Obese Subjects" (SOS) Study. What does weight loss really accomplish?]. / Die "Swedish Obese Subjects"-(SOS)-Studie. Was bringt Abnehmen wirklich?

The Swedish Obese Subjects (SOS) Study was conducted to determine whether obese patients actually can improve their mortality risk by losing weight. After an initial screening study, a total of 6328 subjects were recruited and comprehensively characterized. In the following interventional study, 2010 of the subjects underwent surgery for obesity (gastric banding, gastroplasty, gastric bypass) while 2037 chose a conventional form of treatment, and acted as controls (matched pairs). After 10 years, the controls had gained an average of 1.4 kg in weight. The surgical subjects, in contrast, showed an appreciable and persisting decrease in weight. In comparison with the control group, this group showed a clear decrease in the incidence of cardiovascular risk factors (among others: hypertension, hypertriglyceridemia, diabetes) as well as an improvement in cardiac function parameters and health-related quality of life. On the basis of the present data, however, no definitive pronouncement on the relationship between weight reduction and decrease in overall mortality rate can yet be made.

Principles for enhanced recruitment of subjects in a large clinical trial. the XENDOS (XENical in the prevention of Diabetes in Obese Subjects) study experience.

In most clinical trials it is problematic to recruit enough patients within a reasonable time period. Prolonged or inefficient recruitment or both can have negative scientific and economic consequences. The XENDOS (XENical in the prevention of Diabetes in Obese Subjects) study is an ongoing randomized, double-blind, placebo-controlled, prospective, multicenter trial investigating whether orlistat combined with hypocaloric diet and moderate physical exercise can reduce the incidence of diabetes in obese subjects. To implement the XENDOS protocol and recruit the study patients, we designed a system for centralized patient recruitment and centralized scheduling of patients and staff at the 22 collaborating centers. The recruitment and inclusion phase was divided into a series of different consecutive examinations of increasing complexity. Relatively simple initial examinations enabling a large throughput of patients were followed by more detailed examinations of fewer subjects, by then known to fulfil some of the study-specific requirements. With the aid of object-oriented techniques, the software was modularized to enable concurrent engineering. We also selected a structure where plug-in modules handling specific tasks could be added to the system as needed. The design was supported by a flow-oriented view of the progress of the patients through the study. With this overall solution we managed to include 3305 subjects (98.8% of the requested number) within less than 4 months. The sex distribution (44.8% men) and the number of patients with impaired glucose tolerance (IGT), (21.1%) were in close accordance with, or far better than, the requirements of the protocol (45% men, at least 10% IGT patients). The basic design of the XENDOS information system can be adapted to fulfil the requirements of other study protocols within the fields of obesity, diabetes, hypertension, coronary heart disease, etc. Shortening the recruitment and inclusion phase of large clinical trials is of great value both to be medical society and the pharmaceutical industry.

The Swedish Obese Subjects (SOS) study--rationale and results.

OBJECTIVE: Obesity is associated with increased morbidity and mortality. Several observational epidemiological studies have indicated that weight gain and weight loss, even in the obese, is also related to an increased mortality. The Swedish Obese Subjects (SOS) study was initiated in 1987 as an attempt to elucidate this paradox. DESIGN: Two thousand matched patient pairs will be followed for 10 y each. One pair member is surgically treated, while the other receives conventional obesity treatment. By February 2000, 1879 patient pairs have been recruited. RESULTS: The two-y weight reduction was 28+/-15 kg among the operated patients and 0.5+/-8.9 kg among the obese controls. After eight years the weight loss was 20+/-16 kg in the surgical group, while the controls had gained 0.7+/-12 kg. Weight reductions achieved in the surgical group reduced the two-y incidence of diabetes 32 times as compared to the controls. After eight years there was still a 5-fold reduction in diabetes incidence. The two-y incidence of hypertension was similarly reduced 2.6 times in the surgical group. After eight years the incidence of hypertension was almost equal in the two study groups. CONCLUSION: Compared to weight stability, large intentional weight loss results in substantial reductions in the two-y incidence of several cardiovascular risk factors. After eight years there is still a reduced risk of developing diabetes in the surgical group, while the incidence of hypertension is equal in the two treatment groups. Whether intentional weight loss will reduce mortality is still too early to tell.

[VLCD a safe and simple treatment of obesity]. / VLCD säker och enkel behandling av fetma.

This review summarizes Swedish experience with VLCD (Very Low Calorie Diets). VLCD-treatment is a safe and relatively simple way to induce weight reduction in obese patients. The rapid and profound initial weight loss reduces cardiovascular risk factors and relieves obesity-associated symptoms. Weight loss on the order of 20-25 kg is common after 12-16 weeks of treatment. The long-term results, about 10% weight reduction after two years, are similar to what can be expected with pharmacological treatment. VLCD's should be incorporated into long-term treatment programs including diet, physical exercise and lifestyle modification. A team of nurses and/or dieticians can, to a large extent, manage a VLCD-program, restricting the need for involvement of the physician.

A low serum leptin level at baseline and a large early decline in leptin predict a large 1-year weight reduction in energy-restricted obese humans.

The difficulty in maintaining weight loss during obesity treatment may be caused by a counteracting neuroendocrine response. It has been proposed that leptin could be a regulator of this response. We examined the relations between leptin levels during an initial very low calorie diet, other simultaneous endocrine changes, and the 1-yr weight reduction. Sixty-nine obese (24 men and 45 women) were treated with very low calorie diet for 16 weeks, followed by a hypocaloric diet for 32 weeks. Serum levels of leptin, insulin, cortisol, and thyroid hormones were measured at weeks 0, 8, and 18. The relative weight reductions after 18 and 48 weeks were 20.1% and 14.4% in men and 15.4% and 11.8% in women. Low initial leptin levels and large declines in serum leptin were associated with a large 1-yr weight loss in both genders. Leptin levels (baseline or changes) were not independently associated with the changes in insulin, cortisol, or thyroid hormones. Our results may indicate that leptin by itself could be of minor importance for the neuroendocrine response to severe caloric restriction in humans.

Effects on body weight of strict or liberal adherence to an initial period of VLCD treatment. A randomised, one-year clinical trial of obese subjects.

OBJECTIVES: To examine the impact on early and late weight loss of three different, initial very low calorie diet (VLCD) approaches in a one-year obesity treatment program. DESIGN: Randomised clinical trial. SUBJECTS: 121 obese subjects, aged 21-60y, BMI > or = 30.0kg/m2. INTERVENTIONS: The VLCD-strict group was prescribed a strict outpatient VLCD for 16 weeks, followed by a 36-week hypocaloric diet. The VLCD-mw group received the same treatment, but were hospitalised in a metabolic ward for the initial week. The VLCD-plus group was allowed two small meals weekly, but received otherwise the same recommendations as the VLCD-strict group. RESULTS: After 16 weeks, there was no difference in weight loss between the treatment groups in the intent-to-treat population, while among completers, the weight loss was about 7 kg larger in the VLCD-strict group compared to the VLCD-plus group (P < 0.05). At one year, these groups differed by approximately 4 kg, both according to intention-to-treat and among completers (P < 0.05, both differences). These differences were more prominent among females. The weight reduction in the VLCD-mw group was generally not superior to the VLCD-strict group. CONCLUSIONS: In the short-term, strict VLCD only reduced weight better than a liberal VLCD approach among completers. However, after one year, a strict VLCD regimen seemed beneficial compared to a liberal VLCD for all patients. There was no extra weight loss if the VLCD period was initiated on a metabolic ward.

Familial predisposition for obesity may modify the predictive value of serum leptin concentrations for long-term weight change in obese women.

Leptin is believed to play a role in regulating food intake and body weight. The aim of this study was to examine the influence of parental history of obesity on the association between baseline serum leptin concentrations and subsequent 4-y weight changes. Changes in food intake were also considered in the analysis. Middle-aged, obese women with no obese parent (n = 25) or at least one obese parent (n = 24) were included in the analysis. At baseline, women with no parental history of obesity and women with a parental history of obesity did not differ in body mass index (in kg/m2: 41.2 and 40.2, respectively) or median leptin concentrations (40.8 and 38.8 microg/L, respectively). Four-year weight changes varied widely in both groups combined (from -30 to 24 kg). Stratified regression analysis, adjusted for age, weight, and height, revealed that high leptin concentrations predicted less weight gain (or more weight loss) in women with no obese parent (beta = -21.2, P = 0.0006) but played no significant role in predicting weight gain in women with at least one obese parent (beta = -3.8, P = 0.41). Adding changes in energy and fat intakes to the model reduced the association between leptin and weight change to nonsignificance in the women with no obese parent, indicating that the effect of leptin could be explained largely by dietary changes. In conclusion, serum leptin concentrations predict long-term weight change in obese women with no history of parental obesity, an association largely mediated by changes in food intake.