Leptin-Melanocortin pathway variants and gastric emptying in patients with obesity

BACKGROUND

Accelerated gastric emptying (GE) is a trait seen in obesity. Mutations in the hypothalamic leptin-melanocortin 4 receptor (Leptin-MC4R) pathway have been associated with obesity. We sought to investigate the association of leptin-MC4R pathway variants and GE in patients with obesity.

METHODS

This is a cross-sectional study of patients with a history of severe obesity that were genotyped and completed a GE test by scintigraphy. We evaluated the percentage of GE (GE %) at 2 and 4 h between both groups using ANCOVA with weight and sex as covariates. We subdivide patients into carriers based on the location of the identified variants (i.e., upstream or downstream of the Leptin-MC4R pathway) and compared them with noncarriers using ANOVA. Results are presented as mean and standard deviation (± SD).

KEY RESULTS

A total of 95 patients; nine carriers (67% females; 39.78 ± 12.33 years; BMI: 49.14 ± 12.96 kg/m2) and 86 noncarriers (87% female; 49.98 ± 13.74 years; BMI: 40.75 ± 6.29 kg/m2) were included. At 2 and 4 h, carriers had a delayed GE when compared noncarriers (p = 0.03 and p = 0.005, respectively). In carriers, when compared upstream carriers vs. downstream carriers vs. noncarriers by location there was a significant difference in GE among groups at 2 h and at 4 h (p = 0.02 and p = 0.01, respectively).

CONCLUSIONS & INFERENCES

Carriers of heterozygous variants in the Leptin-MC4R pathway had a delayed GE compared to noncarriers. These findings point the important relationship between the Leptin-MC4R pathway and gastric motility.

The association between previous use of anti-obesity medication and semaglutide weight loss outcomes

AIMS

To compare weight loss outcomes between patients starting semaglutide who had previously been on another anti-obesity medication (AOM) compared to those who were AOM-naïve.

MATERIALS AND METHODS

We performed a retrospective study in patients with overweight or obesity taking semaglutide for weight loss for a duration of 3 to 12 months. Our primary endpoint was assessment of percentage of total body weight loss (TBWL) in patients who started semaglutide as their first AOM (AOM-naïve) compared to those who started semaglutide and had previously taken another AOM (non-AOM-naïve). The secondary outcome was a comparison of the proportions of patients achieving ≥5%, ≥10%, ≥15% and ≥20% TBWL between the groups. Our endpoints were analysed using independent t-tests and ANOVA/ANCOVA for continuous variables and Pearson's test for categorical variables.

RESULTS

This study included 305 patients. Outcomes of semaglutide treatment were superior in AOM-naïve patients (n = 231) compared to non-AOM-naïve patients (n = 74) at 3 (6.3% vs. 3.8%), 6 (10.6% vs. 6.7%), 9 (14.0% vs. 9.1%) and 12 months (14.3% vs. 10.6%; p < 0.0001 at 3, 6 and 9 months, and p = 0.01 at 12 months). A greater proportion of patients in the AOM-naïve group achieved a TBWL ≥ 15% (48% vs 21%; p = 0.02) and ≥20% (27% vs 4% p < 0.01) at 12 months.

CONCLUSION

The use of semaglutide in patients with previous intake of other AOMs was associated with inferior weight loss outcomes in comparison to patients who were AOM-naïve.

Cumulative effect of obesity phenotypes on body weight and body mass index

BACKGROUND

Obesity originates from an imbalance between energy intake and expenditure. Changes in energy intake components (satiation, postprandial satiety, emotional eating) and energy expenditure have been linked to obesity and are referred to as obesity phenotypes. We aim to study if these obesity phenotypes have a cumulative effect on body weight and body mass index (BMI).

SUBJECT/METHODS

This is a cross-sectional study of adult patients with obesity (BMI > 30 kg/m2) who completed the validated tests to measure the obesity phenotypes. A total of 464 were included in this study.

INTERVENTIONS/METHODS

We defined higher calories to fullness during an ad libitum meal as abnormal satiation, accelerated time to half gastric emptying with scintigraphy as abnormal postprandial satiety, higher anxiety score on the Hospital Anxiety and Depression Scale as hedonic eating behavior, and decreased percentage of measured resting energy expenditure as abnormal energy expenditure. The primary analysis was done on the number of phenotypes ( ≤ 1 and ≥ 2) with body weight and BMI using an independent t-test.

RESULTS

Our cohort included 464 patients (mean [SD] age 42.0 [10.9] years, 79% females, weight 111.2 [22.9] kg, BMI 38.9 [7.0] kg/m2). There were 294 patients who had ≤ 1 phenotype, and 170 patients with ≥ 2 phenotypes with no baseline demographical differences (i.e., age and sex). Having ≥ 2 phenotypes was associated with higher body weight (115 [25] kg vs. 109 [21] kg; p = 0.004), BMI (40 [8] kg/m2 vs. 38 [7] kg/m2; p = 0.02) and waist (118 [15] cm vs. 115 [13] cm; p = 0.04) and hip (129 [14] cm vs. 125 [13] cm; p = 0.01) circumferences compared to ≤ 1 phenotype.

CONCLUSION

Obesity phenotypes are associated with an additive effect on the body weight and BMI. Patients who have multiple obesity phenotypes may require a more aggressive approach to enhance weight loss.

Analysis of 1999-2017 NHANES Data: Minimal Increase and Racial Disparities in U.S. Fiber Consumption Over 18 Years

Low dietary fiber consumption is associated with an increased risk of colorectal cancer, a leading cause of cancer-related mortality in the United States. The average daily fiber intake has declined over recent decades. Notably, Black Americans exhibit lower fiber consumption than other racial/ethnic groups, possibly influencing their elevated colorectal cancer rates. We hypothesize that there has been a significant increase in dietary fiber consumption in the United States from 1999 to 2017. The study encompassed 59,204 adult NHANES participants and observed variations in caloric intake over survey years. Although there was a slight overall increase in dietary fiber intake compared to 1999, the most substantial increment occurred among individuals classified as Hispanic (AD: +2.86 g, P < 0.001), followed by non-Hispanic Black (AD: +1.64 g, P < 0.001), and finally non-Hispanic White showed a decrease in fiber intake (AD: -0.86 g, P < 0.001). The findings suggest a modest rise in fiber consumption from 1999 to 2017, but disparities persist, particularly with non-Hispanic Black individuals consuming the least fiber. This emphasizes the need for interventions to promote fiber intake and address racial/ethnic inequalities in dietary habits.

Weight regain after total meal replacement very low-calorie diet program with and with-out anti-obesity medications

Background

Very low-calorie diets (VLCDs) employing total meal replacement (TMR) offer substantial short-term weight loss. Concurrently, anti-obesity medications (AOMs) have shown promise as adjunctive treatments when combined with VLCDs.

Aims

This study aimed to investigate the impact of adjuvant AOMs on weight loss and weight regain within a comprehensive lifestyle program.

Methods

This is a retrospective study of patients with obesity enrolled in VLCD/TMR programs,  specifically the OPTIFAST program.

Results

Data from 206 patients (68% women, mean age 52.39 ± 13.05 years, BMI 41.71 ± 7.04 kg/m2) were analyzed. Of these, 139 received no AOM (AOM-), while 67 received AOMs (AOM+). Total body weight loss percentages (TWL%) at 6 and 18 months were -17.87% ± 7.02 and -12.10% ± 11.56, respectively. There was no significant difference in 6-month weight loss between the AOM groups. However, the AOM + group exhibited lower weight regain (3.29 kg ± 10.19 vs. 7.61 kg ± 11.96; p = 0.006) and weight regain percentage (WR%) (31.5% ± 68.7 vs. 52.16% ± 64.4; p = 0.04) compared with the AOM- group.

Conclusion

The findings highlighted the potential of AOMs and VLCD/TMR as effective strategies for long-term weight management in individuals with obesity.

Weight loss and cardiovascular disease risk outcomes of semaglutide: a one-year multicentered study

BACKGROUND/OBJECTIVE

There are limited real-world studies assessing semaglutide weight loss and associated comorbidity and metabolic outcomes over periods ≥ 6 months. We aim to assess weight loss, metabolic, and cardiovascular outcomes of 12 months of semaglutide.

SUBJECT/METHODS

We conducted a multicentered retrospective cohort study on semaglutide use. We included patients with a body-mass index (BMI) ≥ 27 kg/m2 who were prescribed weekly semaglutide subcutaneous injections. We excluded patients with bariatric surgeries, taking other anti-obesity medications, and with active malignancy or pregnancy. A total of 1023 patients had semaglutide prescription for obesity.

INTERVENTION/METHODS

We assessed weight loss outcomes of subcutaneous semaglutide for 12 months. The primary endpoint was total body weight loss percentage (TBWL%) at 12 months. Secondary endpoints included proportion of patients achieving ≥5%, ≥10%, ≥15%, and ≥20% weight loss, and improvements in metabolic, cardiovascular, and comorbidities after 12 months of follow-up.

RESULTS

We included 304 patients (73% female, 93% White, mean age 48.8 [12.4] years, BMI 40.9 [9.6] kg/m2) in the analysis. Patients achieved a TBWL of 13.4 (8.0)% at 12 months (p < 0.001 from baseline). Patients without T2DM achieved a TBWL of 16.9 (6.9)% compared to 9.9 (8.4)% in patients without T2DM at 12 months on the higher doses of semaglutide (p < 0.001 from baseline). In this cohort, 81% achieved ≥5%, 64% achieved ≥10%, 41% achieved ≥15%, and 22% achieved ≥20% TBWL at 12 months. Patients with overweight or obesity experienced significant improvements in metabolic, lipid profile, blood pressure, liver function tests, and cardiovascular disease risk outcomes.

CONCLUSIONS

Semaglutide demonstrated notable improvement in obesity, metabolic, and cardiovascular disease risk outcomes in a clinical setting.

Neurohormonal response patterns to hunger, satiation, and postprandial fullness in normal weight, anorexia nervosa, and obesity

BACKGROUND

Food intake is regulated by homeostatic and hedonic systems that interact in a complex neuro-hormonal network. Dysregulation in energy intake can lead to obesity (OB) or anorexia nervosa (AN). However, little is known about the neurohormonal response patterns to food intake in normal weight (NW), OB, and AN.

MATERIAL & METHODS

During an ad libitum nutrient drink (Ensure®) test (NDT), participants underwent three pseudo-continuous arterial spin labeling (pCASL) MRI scans. The first scan was performed before starting the NDT after a > 12 h overnight fast (Hunger), the second after reaching maximal fullness (Satiation), and the third 30-min after satiation (postprandial fullness). We measured blood levels of ghrelin, cholecystokinin (CCK), glucagon-like peptide (GLP-1), and peptide YY (PYY) with every pCASL-MRI scan. Semiquantitative cerebral blood flow (CBF) maps in mL/100 gr brain/min were calculated and normalized (nCBF) with the CBF in the frontoparietal white matter. The hypothalamus (HT), nucleus accumbens [NAc] and dorsal striatum [DS] were selected as regions of interest (ROIs).

RESULTS

A total of 53 participants, 7 with AN, 17 with NW (body-mass index [BMI] 18.5-24.9 kg/m2 ), and 29 with OB (BMI ≥30 kg/m2 ) completed the study. The NW group had a progressive decrease in all five ROIs during the three stages of food intake (hunger, satiation, and post-prandial fullness). In contrast, participants with OB showed a minimal change from hunger to postprandial fullness in all five ROIs. The AN group had a sustained nCBF in the HT and DS, from hunger to satiation, with a subsequent decrease in nCBF from satiation to postprandial fullness. All three groups had similar hormonal response patterns with a decrease in ghrelin, an increase in GLP-1 and PYY, and no change in CCK.

CONCLUSION

Conditions of regulated (NW) and dysregulated (OB and AN) energy intake are associated with distinctive neurohormonal activity patterns in response to hunger, satiation, and postprandial fullness.

Obesity: A Review of Pathophysiology and Classification

Obesity is a chronic, multifactorial, and morbid disease. In the United States, 69% of adults are overweight or have obesity, and the global prevalence of obesity is increasing. Obesity is influenced by genetic, neurologic, metabolic, enteric, and behavioral processes. It remains a key modifiable risk factor for many comorbid diseases, including cardiovascular disease, diabetes mellitus, and cancer. Whereas there are recent and significant advances in obesity therapy, including diets, lifestyle modifications, pharmacotherapies, endoscopic procedures, and bariatric surgeries, there is an immense need for a better understanding of the heterogeneity in the pathophysiologic process of obesity and outcomes. Here we review salient pathophysiologic mechanisms underlying the development and morbidity of obesity as well as pathophysiologically based classification systems that inform current obesity management and may inform improved and individualized management in the future.

Type 2 Diabetes Remission in Patients with Heterozygous Variants in the Leptin-Melanocortin Pathway after Roux-en-Y Gastric Bypass: A Matched Case-Control Study

BACKGROUND

Roux-en-Y gastric bypass (RYGB) is associated with a high rate of type 2 diabetes (T2D) remission. Carriers of heterozygous variants in the leptin-melanocortin pathway (LMP) are more likely to experience weight recurrence after RYGB. Our aim was to investigate if carrier status and associated weight regain affects the rate of T2D remission after RYGB.

METHODS

Carriers of LMP variants with a diagnosis of T2D prior to RYGB (N = 16) were matched to non-carriers (N = 32) based on sex, age, and BMI. We assessed for post-operative T2D remission status post-surgery on a yearly basis, for up to 15 years. Our primary endpoint was the proportion of patients achieving T2D remission at 1 year. We conducted a survival analysis for all patients that achieved remission at least at one time-point to evaluate for maintenance of T2D remission by using a log-rank test.

RESULTS

Both carriers and non-carriers had similar baseline and procedural characteristics. The proopiomelanocortin gene in the LMP pathway had the most variants (n = 5, 31%). Carriers had a lower total body weight loss percentage at nadir (28.7% ± 6.9) than non-carriers (33.7% ± 8.8, p = 0.04). The proportion of patients achieving T2D remission at 1 year was 68.8% for carriers and 71.9% for non-carriers (p = 1.0). Survival curves for maintenance of first remission were similar for both groups (p = 0.73), with a median survival of 8 years for both carriers and non-carriers.

CONCLUSIONS

Despite inferior weight loss outcomes at nadir, carriers had similar T2D remission rates when compared to non-carriers. Weight-independent metabolic benefits of RYGB might contribute to this observation.

Phenotype tailored lifestyle intervention on weight loss and cardiometabolic risk factors in adults with obesity: a single-centre, non-randomised, proof-of-concept study

Background

Lifestyle interventions for weight loss are currently not individualised to underlying pathophysiology and behavioral traits in obesity. We aim to compare the outcome of a standard lifestyle intervention (SLI) to phenotype-tailored lifestyle interventions (PLI) on weight loss, cardiometabolic risk factors and physiologic variables contributing to obesity.

Methods

This 12-week, single-centre non-randomised proof-of-concept clinical trial including men and women aged 18-65 years with a body mass index (BMI) greater than 30 without history of any bariatric procedure, and current use of any medication known to affect weight. Participants lived anywhere in the United States, and underwent in-person testing in Rochester, MN at a teaching hospital. All participants completed in-person phenotype testing at baseline and after 12 weeks. Participants were assigned to their intervention based on their period of enrollment. In the first phase, participants were assigned to SLI with a low-calorie diet (LCD), moderate physical activity, and weekly behavioral therapy sessions. In the second phase, other participants were assigned to PLI according to phenotype: abnormal satiation (time-restricted volumetric LCD); abnormal postprandial satiety (LCD with pre-meal protein supplementation); emotional eating (LCD with intensive behavioral therapy); and abnormal resting energy expenditure (LCD with post-workout protein supplementation and high-intensity interval training). The primary outcome was total body weight loss in kg at 12 weeks using multiple imputation for missing data. Linear models estimated the association of study group allocation and study endpoints adjusting for age, sex, and baseline weight. This study was registered with ClinicalTrials.gov, NCT04073394.

Findings

Between July 2020 and August 2021, 211 participants were screened, and 165 were assigned to one of the two treatments in the two phases: 81 SLI (mean [SD] age 42.9 [12] years; 79% women; BMI 38.0 [6.0]) and 84 PLI (age 44.8 [12.2] years; 83% women; BMI 38.7 [6.9]); 146 completed the 12-week programs. The weight loss was -7.4 kg (95%CI, -8.8, -6.0) with PLI vs. -4.3 kg (95%CI, -5.8, -2.7) with SLI (difference, -3.1 kg [95%CI, -5.1 to -1.1]; P = 0.004). No adverse events were reported in any group.

Interpretation

Phenotype-tailored lifestyle interventions may result in significant weight loss, but a randomised controlled trial is required to confirm causality.

Funding

Mayo Clinic; NIH (K23-DK114460).

Cardiovascular Risk and Diseases in Patients With and Without Leptin-Melanocortin Pathway Variants

OBJECTIVE

To study differences in cardiovascular risk factors and diseases between patients with and without genetic variants in the leptin-melanocortin pathway.

METHODS

A cross-sectional study of patients with a history of severe obesity genotyped in June 2019 as participants of the Mayo Clinic Biobank was conducted in March 2022 to assess differences in cardiovascular risk and diseases between carriers of a heterozygous variant in the leptin-melanocortin pathway and noncarriers. Cardiovascular risk factors included hypertension, diabetes, dyslipidemia, and smoking. Cardiovascular disease includes coronary artery disease, peripheral artery disease, and cerebrovascular accidents. Patients with a history of bariatric surgery were excluded. We used logistic regression models to estimate the odds ratio and 95% CI, adjusting for age, body mass index (BMI), and sex.

RESULTS

Among a total of 168 carriers (8%; 121 [72%] female; mean [SD] age, 65.1 [14.9] years; BMI, 44.0 [7.4] kg/m2) and 2039 noncarriers (92%; 1446 [71%] female; mean [SD] age, 64.9 [14.4] years; BMI, 42.9 [6.6] kg/m2), carriers had higher prevalence odds of hypertension (odds ratio, 3.26; 95% CI, 2.31 to 4.61; P<.001) and reported higher number of cardiovascular risk factors compared with noncarriers (2.4 [1.1] vs 2.0 [1.1]; P<.001). There were no significant differences in the adjusted odds associated with diabetes, dyslipidemia, smoking, or cardiovascular disease.

CONCLUSION

Despite having similar body weight and BMI, carriers of heterozygous variants in the leptin-melanocortin pathway had higher rates of hypertension than noncarriers. These findings point to an association between hypertension and leptin-melanocortin pathway variants.

Sex as an independent variable in the measurement of satiation: a retrospective cohort study

BACKGROUND

Satiation is a key component of food intake regulation as it brings an eating episode to an end. The effect of sex on satiation measurement has not been characterized.

OBJECTIVE

To assess the effects of biological variables on satiation.

DESIGN

Retrospective cohort study. We included 959 participants (mean age 39 [SD 12] years; 70.7% female, and BMI 33 kg/m2 [8]) who had measurements of satiation with a nutrient-drink test to assess volume to fullness (VTF) and maximum tolerated volume (MTV), and/or an ad libitum meal test to assess calories consumed to fullness (CTF). We performed univariate and multiple regression analyses to estimate the contribution of sex to VTF, MTV, and CTF, compared to other biological variables, such as age, weight, height, BMI, waist-to-hip circumference (W/H), and lean mass percentage (LM%), that are known to affect these parameters.

RESULTS

Females had higher BMI, W/H, and LM%. VTF, MTV, and CTF were lower in females: 704 [323] vs. 783 [328] mL, p = 0.001; 1226 [384] vs. 1419 [410] mL, p < 0.001; and 871 [291] vs. 1086 [326] kcal, p < 0.001; respectively. Sex was a strong and independent predictor of VTF, MTF and CTF: parameter estimate [PE] = -80.8, p = 0.006; PE = -124.2, p = 0.0007; and PE = -110, p = 0.001; respectively.

CONCLUSIONS

Sex has a strong effect on satiation measured by VTF, MTV, and CTF, even after adjusting for other biological factors known to affect these parameters. Females seem to integrate intra-meal inhibition signals to consume fewer calories unrelated to body size or composition.

CLINICAL TRIAL REGISTRATION

None.

A comparison between weight loss outcomes with anti-obesity medications before and during Covid-19 pandemic at a tertiary weight management center

Background

/Objectives: Obesity is a risk factor for COVID-19 infection severity and mortality. Anti-obesity medications (AOM) are effective for weight loss. However, weight loss outcomes with AOM during the COVID-19 pandemic are yet to be described.

Subjects

/Methods: Between January 1, 2016, and June 30, 2021, a total of 966 patients were prescribed long-term FDA-approved AOMs at the Mayo Clinic. From these patients, 711 patients did not meet inclusion criteria. A total of 255 patients were included.

Interventions/methods

We performed a retrospective systematic review of electronic medical records and included patients who started a long-term FDA-approved AOM. We excluded patients with history of bariatric procedure, AOM prescription with lorcaserin, orlistat, semaglutide (approved for weight loss after the pandemic), or phentermine (short-term AOM), those taking ≥2 AOMs, <3 months of prescribed AOM, and/or pregnancy. Analysis was divided by 1)preCOVID-19: those who started an AOM before COVID-19 restrictions, 2)COVID-19: those who started an AOM during first quarter of 2020 after the establishment of COVID-19 restrictions. Our primary endpoint was the total body weight loss percentage (%TBWL) at 3, 6, and 12 months after AOM initiation.

Results

There was a statistical difference in TBWL% between the preCOVID-19 and COVID-19 group: 5.3 ± 3.5% vs 4 ± 3.0% (95% CI -2.4 to -0.2; p = 0.02) and 9.7 ± 7.2% vs 6.2 ± 4.7% (95% CI -5.7 to -1.3; p = 0.002) at 3 and 12 months, respectively. At 6 months, the TBWL% was 7.1 for the preCOVID-19 group compared to 6.2% for the COVID-19 (95% CI -2.5 to 0.7; p = 0.25).

Conclusion

With the possible exception of liraglutide, this study shows that weight loss outcomes to AOMs were inferior when prescribed during the routine clinical practice throughout COVID-19 pandemic, compared to the outcomes observed prior to the COVID-19 pandemic.

Association between anxiety and eating behaviors in patients with obesity

Background

Given the link between eating behavior and obesity, it is critical to identify individuals who have eating behaviors which contribute to obesity etiology. This study aimed to investigate the potential relationship between symptoms of anxiety and eating behaviors in patients with obesity.

Methods

This was a cross-sectional study analyzing baseline characteristics of 438 patients with obesity (BMI>30). Patients completed the Hospital Anxiety and Depression Scale (HADS) questionnaire, the Three-Factor Eating Questionnaire R21 (TFEQ-R21), and the Weight Efficacy Lifestyle Questionnaire (WEL). Pearson correlation coefficients were used to evaluate the association between questionnaires. Two-sample independent t-test were conducted to examine differences in the TFEQ-R21 and WEL between low and moderate to severe levels of symptoms of anxiety.

Results

Anxiety scores (HADS-A) positively correlated with two factors of the TFEQ, emotional eating (r = 0.36) and uncontrolled eating (r = 0.27). The HADS-A score was negatively correlated with self-efficacy to resist eating in all five situational factors on the WEL (p < 0.01). Patients with symptoms of anxiety additionally showed higher mean scores for emotional eating and uncontrolled eating (p < 0.001, respectively),and lower levels of cognitive restraint (p = 0.04)) on the TFEQ-R21.

Conclusion

Patients with obesity who reported having anxiety symptoms had lower self-confidence to manage their eating and more emotional eating than patients with low anxiety symptoms. Clearly more needs to be learned about symtoms of anxiety and eating behaviors.

Effect of caloric intake and macronutrient composition on intestinal cholesterol absorption and bile acids in patients with obesity

Obesity is associated with alterations in cholesterol and bile acid (BA) metabolism. However, the interaction among dietary intake, cholesterol absorption, and BA metabolism in patients with obesity remains unclear. We conducted a 4-wk nutritional intervention nonrandomized clinical trial with three different sequential diets for a week in the following order: regular diet (RD); high calorie, high-fat diet (HCHF), washout period on RD; and low-calorie, low-fat diet (LCLF). We provided participants with meal replacements during HCHF and LCLF diets. A total of 16 participants completed the study [n = 8 normal weight (NW); n = 8 with obesity (OB)]. Overall, there was a significant increase in intestinal cholesterol uptake when changing from RD to HCHF and a reduction in intestinal cholesterol uptake from HCHF to LCLF. When analyzing by BMI groups, these findings were similar in patients with NW (RD to HCHF: P < 0.007; HCHF to LCLF: P = 0.02); however, in patients with obesity, the change in intestinal cholesterol uptake was only observed when changing from RD to HCHF (P = 0.006). There was no correlation between cholesterol absorption and fecal bile acids or other markers of BA metabolism in all patients or the subgroups. Dietary caloric content had a significant effect on cholesterol absorption, however, this effect is blunted in patients with obesity. These data are consistent with the impaired effect of a low-fat diet on cholesterol absorption in obesity.NEW & NOTEWORTHY We show how switching from a regular diet to an HCHF increases cholesterol absorption in patients with normal weight and obesity. The decrease in cholesterol absorption from an HCHF to an LCLF, on the other hand, was only seen in normal-weight controls, underlining the importance of body weight in this regulation. In addition, changes in caloric and fat content had an immediate and direct effect on hepatic bile acid production.

Weight Loss Outcomes Associated With Semaglutide Treatment for Patients With Overweight or Obesity

IMPORTANCE

No retrospective cohort study has assessed the effectiveness of semaglutide at doses used in randomized clinical trials to treat obesity (ie, 1.7 and 2.4 mg).

OBJECTIVE

To study weight loss outcomes associated with semaglutide treatment at doses used in randomized clinical trials for patients with overweight or obesity.

DESIGN, SETTING, AND PARTICIPANTS

This cohort study, conducted at a referral center for weight management, retrospectively collected data on the use of semaglutide for adults with overweight or obesity between January 1, 2021, and March 15, 2022, with a follow-up of up to 6 months. A total of 408 patients with a body mass index (BMI) of 27 or more were prescribed weekly semaglutide subcutaneous injections for 3 months or more. Patients with a history of bariatric procedures, taking other antiobesity medications, and with an active malignant neoplasm were excluded.

EXPOSURES

Weekly 1.7-mg or 2.4-mg semaglutide subcutaneous injections for 3 to 6 months.

MAIN OUTCOMES AND MEASURES

The primary end point was the percentage of weight loss. Secondary end points were the proportion of patients achieving weight loss of 5% or more, 10% or more, 15% or more, and 20% or more after 3 and 6 months and the percentage of weight loss for patients with or without type 2 diabetes after 3 and 6 months.

RESULTS

The study included 175 patients (132 women [75.4%]; mean [SD] age, 49.3 [12.5] years; mean [SD] BMI, 41.3 [9.1]) in the analysis at 3 months and 102 patients at 6 months. The mean (SD) weight loss after 3 months was 6.7 (4.4) kg, equivalent to a mean (SD) weight loss of 5.9% (3.7%) (P < .001), and the mean (SD) weight loss after 6 months was 12.3 (6.6) kg, equivalent to a mean (SD) weight loss of 10.9% (5.8%) (P < .001 from baseline). Of the 102 patients who were followed up at 6 months, 89 (87.3%) achieved weight loss of 5% or more, 56 (54.9%) achieved weight loss of 10% or more, 24 (23.5%) achieved weight loss of 15% or more, and 8 (7.8%) achieved weight loss of 20% or more. Patients with type 2 diabetes had a lower mean (SD) percentage weight loss at 3 and 6 months compared with those without type 2 diabetes: 3.9% (3.1%) vs 6.3% (3.7%) at 3 months (P = .001) and 7.2% (6.3%) vs 11.8% (5.3%) at 6 months (P = .005).

CONCLUSIONS AND RELEVANCE

The results of this cohort study suggest that weekly 1.7-mg and 2.4-mg doses of semaglutide were associated with weight loss similar to that seen in randomized clinical trials. Studies with longer periods of follow-up are needed to evaluate prolonged weight loss outcomes.

Association Between Food Intake and Gastrointestinal Symptoms in Patients With Obesity

BACKGROUND AND AIMS

Hunger, satiation, postprandial satiety, and hedonic eating constitute key food intake parameters. We aim to study whether these symptoms are associated with gastrointestinal symptoms (GIS) in patients with obesity.

METHODS

This is a cross-sectional study of patients with obesity. Patients completed the following validated biomarkers and questionnaires: hunger was measured via visual analog scale (100 mm) following a standard meal, satiation was measured via ad libitum meal (calories to fullness; kcal), postprandial satiety was measured via gastric emptying scintigraphy (T_1/2; mins), and hedonic eating was measured via the Hospital Anxiety and Depression Scale questionnaire. Participants completed the abridged Bowel Disease Questionnaire to evaluate their GIS. We calculated the odds ratios (ORs) adjusted for sex, weight, and age between food intake parameters <25^th or >75^th percentile observed in a prior cohort of 450 participants with obesity and GIS.

RESULTS

A total of 274 participants (41 ± 10 [SD] years, 75% females, body mass index 39 ± 8 kg/m²) were included in the analysis. Increased hunger was associated with a lower prevalence of lumpy stools (OR = 0.18, P = .02). Satiation was associated with abdominal pain/discomfort (relieved by defecation [OR = 2.4, P = .02] or associated with change in stool consistency [OR = 2.92, P < .01]), loose/watery stools (OR = 2.09, P = .02), and bloating (OR = 2.49, P < .01). Abnormal postprandial satiety was associated with bloating (OR = 2.26, P < .01) and loose/watery stools (OR = 1.84, P = .04). Hedonic eating was associated with abdominal pain/discomfort with stool frequency change (OR = 2.4, P = .02), >3 bowel movements per day (OR = 1.93, P = .048), bloating (OR = 2.49, P = .01), abdominal pain after meals >1 per month (OR = 4.24, P < .01), and nausea >1 per week (OR = 4.51, P < .01).

CONCLUSION

Alterations in hunger, satiation, postprandial satiety, and hedonic eating are associated with GIS in patients with obesity.

Association between CYP metabolizer phenotypes and selective serotonin reuptake inhibitors induced weight gain: a retrospective cohort study

BACKGROUND

Prescription medications such as selective serotonin reuptake inhibitors (SSRIs), commonly used to treat depression, are associated with weight gain. The role of pharmacogenomics in predicting SSRI-induced weight gain is unclear.

METHODS

In this retrospective cohort study from participants in the Mayo Clinic RIGHT study who were prescribed citalopram, paroxetine, sertraline, or fluoxetine, our aim was to evaluate the association of metabolizer phenotype and total body weight after 6 months of SSRIs initiation. We evaluated the metabolizer phenotypes (poor/intermediate, normal, and rapid/ultra-rapid) of the cytochromes P450 enzymes genes: CYP2C9, CYP2C19, and CYP2D6 known to influence the metabolism of SSRI medications: CYP2C19 for citalopram, CYP2D6 for paroxetine, CYP2D6 and CYP2C19 for sertraline, and CYP2D6 and CYP2C9 fluoxetine. In addition, we assessed the association of metabolizer phenotype and total body weight change at six months following SSRI prescription using parametric analysis of covariance adjusted for baseline body weight and multivariate regression models.

RESULTS

CYP2C19 poor/intermediate metabolizers prescribed citalopram gained significantly more weight than normal or rapid/ultra-rapid metabolizers at 6 months (TBWG %: 2.6 [95% CI 1.3-4.1] vs. 0.4 [95% CI -0.5 - 1.3] vs. -0.1 [-95% CI -1.5-1.1]; p = 0.001). No significant differences in weight outcomes at six months of treatment with paroxetine, sertraline, or fluoxetine were observed by metabolizer status.

CONCLUSIONS

Weight gain observed with citalopram may be mediated by CYP2C19 metabolizer status.

Effects of Heterozygous Variants in the Leptin-Melanocortin Pathway on Roux-en-Y Gastric Bypass Outcomes: a 15-Year Case-Control Study

INTRODUCTION

Heterozygous variants in the leptin-melanocortin pathway are associated with obesity. However, their effect on the long-term outcomes after Roux-en-Y gastric bypass (RYGB) is still unknown.

METHODS

In this matched case-control study, 701 participants from the Mayo Clinic Biobank with a history of RYGB were genotyped. Sixty-three patients had a heterozygous variant in the leptin-melanocortin pathway. After excluding patients with potential confounders, carriers were randomly matched (on sex, age, body mass index [BMI], and years since surgery) with two non-carrier controls. The electronic medical record of carriers and matched non-carriers was reviewed for up to 15 years after RYGB.

RESULTS

A total of 50 carriers and 100 matched non-carriers with a history of RYGB were included in the study. Seven different genes (LEPR, PCSK1, POMC, SH2B1, SRC1, MC4R, and SIM1) in the leptin-melanocortin pathway were identified. At the time of surgery, the mean age was 50.8 ± 10.6 years, BMI 45.6 ± 7.3 kg/m², and 79% women. There were no differences in postoperative years of follow-up, Roux limb length, or gastric pouch size between groups. Fifteen years after RYGB, the percentage of total body weight loss (%TBWL) in carriers was - 16.6 ± 10.7 compared with - 28.7 ± 12.9 in non-carriers (diff = 12.1%; 95% CI, 4.8 to 19.3) and the percentage of weight regain after maximum weight loss was 52.7 ± 29.7 in carriers compared with 29.8 ± 20.7 in non-carriers (diff = 22.9%; 95% CI, 5.3 to 40.5). The nadir %TBWL was lower - 32.1 ± 8.1 in carriers compared with - 36.8 ± 10.4 in non-carriers (diff = 4.8%; 95% CI 1.8 to 7.8).

CONCLUSIONS

Carriers of a heterozygous variant in the leptin-melanocortin pathway have a progressive and significant weight regain in the mid- and long-term after RYGB. Genotyping patients experiencing significant weight regain after RYGB could help implement multidisciplinary and individualized weight loss interventions to improve weight maintenance after surgery.

Evaluation and Management of Patients Referred for Post-Bariatric Surgery Hypoglycemia at a Tertiary Care Center

PURPOSE

Following bariatric surgery, patients can develop non-specific symptoms self-described as hypoglycemia. However, confirming hypoglycemia can be technically challenging, and therefore, these individuals are frequently treated empirically. This study aimed to describe what diagnostic evaluation and therapeutic interventions patients referred for post-bariatric surgery hypoglycemia undergo.

METHODS

Retrospective observational cohort study of patients with a history of bariatric surgery was evaluated for post-bariatric surgery hypoglycemia in a tertiary referral center from 2008 to 2017. We collected demographic and bariatric surgery information, clinical presentation of symptoms referred to as hypoglycemia, laboratory and imaging studies performed to evaluate these symptoms, and symptom management and outcomes.

RESULTS

A total of 60/2450 (2.4%) patients who underwent bariatric surgery were evaluated in the Department of Endocrinology for hypoglycemia-related symptoms. The majority were middle-aged women without type 2 diabetes who had undergone Roux-en-Y gastric bypass. Thirty-nine patients (65%) completed a biochemical assessment for hypoglycemia episodes. Six (10%) had confirmed hypoglycemia by Whipple's triad, and four (6.7%) met the criteria for post-bariatric surgery hypoglycemia based on clinical and biochemical criteria. All patients were recommended dietary modification as the initial line of treatment, and this intervention resulted in most patients reporting at least some improvement in their symptoms. Eight patients (13%) were prescribed pharmacotherapy, and two patients required additional interventions for symptom control.

CONCLUSIONS

In our experience, evaluation for hypoglycemia-related symptoms after bariatric surgery was rare. Hypoglycemia was confirmed in the minority of patients. Even without establishing a diagnosis of hypoglycemia, dietary changes were a helpful strategy for symptom management for most patients.

Homeostatic regulation of food intake

Food intake and energy expenditure are key regulators of body weight. To regulate food intake, the brain must integrate physiological signals and hedonic cues. The brain plays an essential role in modulating the appropriate responses to the continuous update of the body energy-status by the peripheral signals and the neuronal pathways that generate the gut-brain axis. This regulation encompasses various steps involved in food consumption, include satiation, satiety, and hunger. It is important to have a comprehensive understanding of the mechanisms that regulate food consumption as well as to standardize the vocabulary for the steps involved. This review discusses the current knowledge of the regulation and the contribution peripheral and central signals at each step of the cycle to control appetite. We also highlight how food intake has been measured. The increasingly complex understanding of regulation and action mechanisms intervening in the gut-brain axis offers ambitious targets for new strategies to control appetite.

Effectiveness of anti-obesity medications approved for long-term use in a multidisciplinary weight management program: a multi-center clinical experience

BACKGROUND AND AIMS

Randomized clinical trials have proven the efficacy and safety of Food and Drug Administration (FDA) approved anti-obesity medications (AOMs) for long-term use. It is unclear whether these outcomes can be replicated in real-world clinical practice where clinical complexities arise. The aim of this study was to evaluate the effectiveness and side effects of these medications in real-world multidisciplinary clinical practice settings.

METHODS

We reviewed the electronic medical records (EMR) of patients with obesity who were prescribed an FDA-approved AOM for long-term use in academic and community multidisciplinary weight loss programs between January 2016 and January 2020.

INTERVENTION

We assessed percentage total body weight loss (%TBWL), metabolic outcomes, and side effect profile up to 24 months after AOM initiation.

RESULTS

The full cohort consisted of 304 patients (76% women, 95.2% White, median age of 50 years old [IQR, 39-58]). The median follow-up time was 9.1 months [IQR, 4.2-14.1] with a median number of 3 visits [IQR, 2-4]. The most prescribed medication was phentermine/topiramate extended-release (ER) (51%), followed by liraglutide (26.3%), bupropion/naltrexone sustained-release (SR) (16.5%), and lorcaserin (6.2%). %TBWL was 5.0%, 6.8%, 9.3%, 10.3%, and 10.5% at 3, 6, 12, 18, and 24 months. 60.2% of the entire cohort achieved at least 5% TBWL. Overall, phentermine/topiramate-ER had the most robust weight loss response during follow-up, with the highest %TBWL at 12 months of 12.0%. Adverse events were reported in 22.4% of patients. Only 9% of patients discontinued the medication due to side effects.

CONCLUSIONS

AOMs resulted in significant long-term weight loss, that was comparable to outcomes previously reported in clinical trials.

Precision Medicine for Obesity

Obesity is a multifactorial disease with a variable and underwhelming weight loss response to current treatment approaches. Precision medicine proposes a new paradigm to improve disease classification based on the premise of human heterogeneity, with the ultimate goal of maximizing treatment effectiveness, tolerability, and safety. Recent advances in high-throughput biochemical assays have contributed to the partial characterization of obesity's pathophysiology, as well as to the understanding of the role that intrinsic and environmental factors, and their interaction, play in its development and progression. These data have led to the development of biological markers that either are being or will be incorporated into strategies to develop personalized lines of treatment for obesity. There are currently many ongoing initiatives aimed at this; however, much needs to be resolved before precision obesity medicine becomes common practice. This review aims to provide a perspective on the currently available data of high-throughput technologies to treat obesity.

Association of gastric emptying with postprandial appetite and satiety sensations in obesity

OBJECTIVE

Satiety, defined as the duration of the sensation of fullness, is usually measured by validated visual analog scales (VAS) for appetite. Gastric function plays a key role in food intake regulation. However, the association between gastric emptying (GE) and VAS appetite is unknown.

METHODS

In this cross-sectional study, 134 participants (mean [SEM] age = 39 [0.8] years, mean [SEM] BMI = 38 [0.5] kg/m² , 67% females) completed simultaneous measurements of GE and VAS appetite. After a 320-kcal meal, GE was measured by scintigraphy and appetite by validated 100-mm VAS for 240 minutes. Satiation was defined as calories consumed to terminate meal and was measured by an ad libitum meal. GE, VAS, and ad libitum meal tests were measured on the same day. Percent of meal retention in the stomach, VAS area under curve (AUC_{0-240 min} ), and overall appetite score (OAS) were calculated. Pearson correlation (ρ) determined the association of GE with VAS appetite and satiation. Appetite components were also analyzed by quartiles based on GE_{120 min} .

RESULTS

GE_{120 min} was correlated with sensation of VAS hunger_{AUC(0-240 min)} (ρ = 0.24, p = 0.004), fullness_{AUC(0-240 min)} (ρ = 0.16, p = 0.05), and OAS_{AUC(0-240 min)} (ρ = 0.20, p = 0.02). Patients with rapid GE_{120 min} had a mean increase in VAS hunger_{AUC(0-240 min)} by 32 mm/min (15.62%, p = 0.03) compared with normal/slow GE_{120 min} .

CONCLUSIONS

GE is associated with the sensations of appetite, and rapid GE is associated with increased appetite, which may contribute to weight gain.

Post-bariatric Surgery Outcomes and Complications in Patients with Celiac Disease: a Matched Case-Control Study

PURPOSE

The shift towards an obese phenotype in celiac disease (CD) patients increases risk of morbidity and mortality. Bariatric surgery (BS) is the gold standard treatment for obesity. Few studies have explored the role of BS in patients with CD. This study aimed to assess the effectiveness and safety of BS in this population.

MATERIAL AND METHODS

This is a retrospective matched case-control (1:5) study of adult patients with confirmed CD who underwent BS at our institution from 1998 to 2018. Demographics, operative data, post-operative outcomes, complications, and nutritional parameters were collected.

RESULTS

Seventy-eight patients (mostly Caucasian females) were included. Thirteen had confirmed CD and were compared with 65 controls. The most common type of BS was the RYGB. The percent of total body weight loss (%TWL) was similar for both groups at 6, 12, 18, 24, and 36 months, with the highest weight loss being at 12 months: %TWL 28.4 (20.2-38.4) for CD, n=13; vs. 29.1 (19.6-39.3) for non-CD, n=49; p=0.8. Obesity-associated co-morbidities greatly and comparably improved in both groups. Patients with CD had no complications after BS. Post-BS malodorous and oily stools were more common among patients with CD (23.1% vs. 4.6%, p=0.03). Micronutrient deficiencies were common and comparable among both groups with iron and vitamin D being the most common deficiencies. Gluten-free diet (GFD) non-adherence post-operatively was associated with a higher incidence of post-BS abdominal pain (60.0% vs. 0.0%, p=0.012).

CONCLUSIONS

BS is safe and effective in patients with CD. Close monitoring is necessary to ensure compliance with GFD and vitamin supplementation.

KEY POINTS

• Bariatric surgery leads to significant weight loss in celiac disease (CD) patients. • Mid- and long-term weight loss does not differ between patients with and without CD. • Obesity-associated co-morbidities significantly improve after surgery in CD patients. • The incidence of post-surgical complications is not higher in CD patients.

The Chilean socio-ethno-genomic cline

Studies of the current Chilean population performed using classical genetic markers have established that the Chilean population originated primarily from the admixture of European people, particularly Spaniards, and Amerindians. A socioeconomic-ethno-genetic cline was established soon after the conquest. Spaniards born in Spain or Chile occupied the highest Socioeconomic Strata, while Amerindians belonged to the lowest. The intermediate strata consisted of people with different degrees of ethnic admixture; the larger the European admixture, the higher the Socioeconomic Level. The present study of molecular genomic markers sought to calculate the percentage of Amerindian admixture and revealed a finer distribution of this cline, as well as differences between two Amerindian groups: Aymara and Mapuche. The use of two socioeconomic classifications - Class and Socioeconomic Level - reveals important differences. Furthermore, Self-reported Ethnicity (self-assignment to an ethnic group) and Self-reported Ancestry (self-recognition of Amerindian ancestors) show variations and differing relationships between socioeconomic classifications and genomic Amerindian Admixture. These data constitute a valuable input for the formulation of public healthcare policy and show that the notions of Ethnicity, Socioeconomic Strata and Class should always be a consideration in policy development.

High Rates of Exposures to Waterborne Pathogens in Indigenous Communities in the Amazon Region of Ecuador

Waterborne pathogens, associated with poverty and poor sanitary conditions, are a major cause of morbidity and mortality worldwide. There are limited data on the epidemiology of waterborne pathogens in indigenous populations living in the Amazon region. We did a cross-sectional survey in two indigenous Shuar communities in the Amazon region of Ecuador in which we documented the presence of pathogens representing different sources of environmental contamination of water. We detected protozoa and soil-transmitted helminths by microscopy of fecal samples and the presence of IgG antibodies to hepatitis A and Leptospira spp. in blood samples from individuals older than 2 years and collected data by questionnaire on sociodemographic factors and knowledge of infectious diseases. Seroprevalence for hepatitis A and Leptospira spp. were 98.1% (95% CI: 97.0-99.8) and 50.0% (95% CI: 43.3-56.6), respectively, whereas 62.6% (95% CI: 55.8-69.4) had enteric parasites in stool samples. In participants older than 6 years, eight of 10 had evidence of infection with or exposure to at least one of the pathogens studied. Although prevalence of pathogens varied by age, it did not vary significantly by gender, temporal migration, illiteracy, perceived morbidity, receipt of conditional cash transfers, water boiling practices, poor housing conditions, and anthropometric status. These findings indicate a high level of contamination of drinking water by human pathogens in these indigenous communities and the need for interventions to improve access to and use of clean drinking water in these marginalized communities.

[Growth hormone of dried blood spot for the diagnosis of growth hormone deficiency]

INTRODUCTION

The diagnosis of growth hormone deficiency (GHD) is difficult to determine, and could be associated with severe complications, especially in the neonatal period. The stimulation test of growth hormone (GH) secretion is considered the gold standard for diagnosis, but it has methodological complications and is associated with adverse effects. Neonates present physiological increased secretion of GH, representing a diagnostic window.

OBJECTIVE

To evaluate if the dried blood spot on filter paper obtained in the neonatal period, as part of a neonatal screening for con genital hypothyroidism and phenylketonuria, allows differentiating patients with GHD from those who do not have it.

PATIENTS AND METHOD

Study of cases and controls by measuring the GH concen tration in dried blood spot on filter paper obtained in the neonatal period, comparing controls with GHD with cases with discarded deficiency. The sample was extracted from the filter paper, obtaining two 0.125 inch discs per each patient from the center of the blood spot on the paper, for a highly sen sitive ELISA assay for human GH based on the use of polyclonal antibodies against 22 kDa recom binant human GH.

RESULTS

Seven cases of GHD and ten controls were obtained. The median GH concentration of the dried blood spot in the cases is 2.0 ng/ml (Interquartile range 3.6 ng/ml) and 2.05 ng/ml (Interquartile range 2.0 ng/ml) in the controls, Mann-Whitney U test 30.5 (p = 0.68). The two cases with multiple pituitary-hormone deficiency (MPHD) present concentrations lower than 1 ng/ml.

CONCLUSION

The dried blood spot sample did not differentiate GHD patients from control cases, although MPHD cases present much lower concentrations compared to isolated growth hor mone deficiency (IGHD).

Pollen derived low molecular compounds enhance the human allergen specific immune response in vivo

BACKGROUND

Besides allergens, pollen release bioactive, low molecular weight compounds that modulate and stimulate allergic reactions. Clinical relevance of these substances has not been investigated to date.

OBJECTIVE

To elucidate the effect of a non-allergenic, low molecular weight factors from aqueous birch pollen extracts (Bet-APE < 3 kDa) on the human allergic immune response in vivo.

METHODS

Birch and grass pollen allergic individuals underwent skin prick testing with allergen alone, allergen plus Bet-APE < 3 kDa, or allergen plus pre-identified candidate substances from low molecular pollen fraction. Nasal allergen challenges were performed in non-atopic and pollen allergic individuals using a 3 day repeated threshold challenge battery. Subjects were either exposed to allergen alone or to allergen plus Bet-APE< 3 kDa. Local cytokine levels, nasal secretion weights, nasal congestion and symptom scores were determined.

RESULTS

Skin prick test reactions to pollen elicited larger weals when allergens were tested together with the low molecular weight compounds from pollen. Similar results were obtained with candidate pollen-associated lipid mediators. In nasal lining fluids of allergic patients challenged with allergen plus Bet-APE < 3 kDa, IL-8 and IgE was significantly increased as compared to allergen-only challenged patients. These patients also produced increased amounts of total nasal secretion and reported more severe rhinorrhea than the allergen-only challenged group.

CONCLUSIONS

Low molecular compounds from pollen enhance the allergen specific immune response in the skin and nose. They are therefore of potential clinical relevance in allergic patients.

Rapid molecular detection of pulmonary tuberculosis in HIV-infected patients in Santiago, Chile

SETTING

Santiago, Chile, has a mean annual tuberculosis (TB) rate of 13 per 100 000 population; however, TB incidence in human immunodeficiency virus (HIV) infected individuals is at least 20 times higher.

OBJECTIVE

To assess the accuracy of rapid molecular testing for pulmonary TB (PTB) detection in routine care in HIV-infected patients.

DESIGN

Cross-sectional study, conducted prospectively in five hospitals between March 2010 and June 2011. HIV-positive subjects with suspected PTB provided sputum or mouth wash samples that were directly processed for acid-fast smear, mycobacterial cultures and Xpert® MTB/RIF. Positive test results were reported on the same day.

RESULTS

We enrolled 166 subjects into the study; 50.6% provided two sputum samples, 33.1% only one sputum sample and 16.3% a mouth wash sample. The prevalence of TB was 8.1% (13/160). Diagnostic sensitivity increased from 66.7% (95%CI 39.1-86.2) for acid-fast smear to 91.7% (95%CI 64.6-98.5) for Xpert MTB/RIF, with comparable specificity at 98.6% (146/148, 95%CI 95.2-99.6) and 99.3% (147/148, 95%CI 96.3-99.9). Xpert MTB/RIF allowed early detection of rifampicin resistance in 16.6% of cases, with rapid adjustment to multidrug-resistant treatment.

CONCLUSION

Xpert MTB/RIF provided earlier TB diagnosis in 25% more cases than acid-fast smear alone. Its implementation should be considered for TB diagnosis in HIV-positive patients even outside TB-endemic areas.

The putative serine protease inhibitor Api m 6 from Apis mellifera venom: recombinant and structural evaluation

BACKGROUND

Immunoglobulin (Ig) E-mediated reactions to honeybee venom can cause severe anaphylaxis, sometimes with fatal consequences. Detailed knowledge of the allergic potential of all venom components is necessary to ensure proper diagnosis and treatment of allergy and to gain a better understanding of the allergological mechanisms of insect venoms.

OBJECTIVE

Our objective was to undertake an immunochemical and structural evaluation of the putative low-molecular-weight serine protease inhibitor Api m 6, a component of honeybee venom.

METHODS

We recombinantly produced Api m 6 as a soluble protein in Escherichia coli and in Spodoptera frugiperda (Sf9) insect cells.We also assessed specific IgE reactivity of venom-sensitized patients with 2 prokaryotically produced Api m 6 variants using enzyme-linked immunosorbent assay. Moreover, we built a structural model ofApi m 6 and compared it with other protease inhibitor structures to gain insights into the function of Api m 6.

RESULTS

In a population of 31 honeybee venom-allergic patients, 26% showed specific IgE reactivity with prokaryotically produced Api m 6, showing it to be a minor but relevant allergen. Molecular modeling of Api m 6 revealed a typical fold of canonical protease inhibitors, supporting the putative function of this venom allergen. Although Api m 6 has a highly variant surface charge, its epitope distribution appears to be similar to that of related proteins.

CONCLUSION

Api m 6 is a honeybee venom component with IgE-sensitizing potential in a fraction of venom-allergic patients. Recombinant Api m 6 can help elucidate individual component-resolved reactivity profiles and increase our understanding of immune responses to low-molecular-weight allergens

Api m 10, a genuine A. mellifera venom allergen, is clinically relevant but underrepresented in therapeutic extracts

BACKGROUND

Generalized systemic reactions to stinging hymenoptera venom constitute a potentially fatal condition in venom-allergic individuals. Hence, the identification and characterization of all allergens is imperative for improvement of diagnosis and design of effective immunotherapeutic approaches. Our aim was the immunochemical characterization of the carbohydrate-rich protein Api m 10, an Apis mellifera venom component and putative allergen, with focus on the relevance of glycosylation. Furthermore, the presence of Api m 10 in honeybee venom (HBV) and licensed venom immunotherapy preparations was addressed.

METHODS

Api m 10 was produced as soluble, aglycosylated protein in Escherichia coli and as differentially glycosylated protein providing a varying degree of fucosylation in insect cells. IgE reactivity and basophil activation of allergic patients were analyzed. For detection of Api m 10 in different venom preparations, a monoclonal human IgE antibody was generated.

RESULTS

Both, the aglycosylated and the glycosylated variant of Api m 10 devoid of cross-reactive carbohydrate determinants (CCD), exhibited IgE reactivity with approximately 50% of HBV-sensitized patients. A corresponding reactivity could be documented for the activation of basophils. Although the detection of the native protein in crude HBV suggested content comparable to other relevant allergens, three therapeutical HBV extracts lacked detectable amounts of this component.

CONCLUSION

Api m 10 is a genuine allergen of A. mellifera venom with IgE sensitizing potential in a significant fraction of allergic patients independent of CCD reactivity. Thus, Api m 10 could become a key element for component-resolved diagnostic tests and improved immunotherapeutic approaches in hymenoptera venom allergy.

Stratum corneum lipids, skin barrier function and filaggrin mutations in patients with atopic eczema

BACKGROUND

Prior to the discovery of filaggrin (FLG) mutations, evidence for an impaired skin barrier in atopic dermatitis (AD) has been documented, and changes in ceramide profile, altered skin pH and increased trans-epidermal water loss (TEWL) in patients with AD have been reported. Until now, no studies have analysed stratum corneum (SC) lipids combined with skin barrier parameters in subjects of known FLG genotype.

METHODS

A cohort of 49 German individuals genotyped for the most common FLG mutations (R501X, 2282del4) had SC samples taken for lipid analysis by high-performance thin layer chromatography. In addition, TEWL, erythema, skin hydration and pH were measured. In 27 of the 49 individuals, a 24-h irritation patch test with sodium lauryl sulphate was performed. For the analysis, both the AD group and the control group were stratified by FLG mutation status (FLGmut/FLGwt).

RESULTS

In the FLGmut AD group, significantly lower levels of ceramide 4 and significantly higher levels of ceramide 7 were observed when compared to both healthy control groups. However, ceramide 7 levels also significantly differed between FLGwt AD and FLGwt controls, as did ceramide 1 levels. No significant differences were observed for ceramide 2, 3, 5 and 6. FLGmut individuals had significantly higher skin pH values than individuals not carrying FLG mutations. Patients with AD with FLG mutations had significantly higher erythema compared to patients with AD without FLG mutations.

CONCLUSION

Our results confirm previous observations of altered ceramide levels in AD, which however appear to show no clear relationship with FLG mutations.

CTG repeats at the myotonic protein kinase gene in a healthy Chilean population sample

OBJECTIVES

To study the variability at the myotonic dystrophy protein kinase (DMPK) gene in a Chilean sample of healthy people. DM1 is an autosomal dominant disorder caused by an expansion of a (CTG) repeat at the 3'-UTR of the gene DMPK. Healthy individuals have alleles under 35 repeats and diseased individuals have over 50.

METHODS

Genotyping the number of (CTG) repeats at this gene in a sample of healthy Chilean people.

RESULTS

Allele frequencies were significantly different from those of other populations. The most frequent allele was with five repeats. The frequency of larger alleles (>18 CTG repeats) was 11%, close to the European frequency (12%) and higher than the Japanese (8%) and Aboriginal Pehuenche samples (8%).

CONCLUSIONS

Allelic frequencies in the Chilean sample studied were intermediate between those of the two ancestral populations (European and Pehuenche).

Genetic variants in the enhancer region of the thymidylate synthase gene in the Chilean population

AIMS

Thymidylate synthase (TYMS) is an important target enzyme for the fluoropyrimidines. The TYMS gene enhancer region possesses tandemly repeated (TSER) sequences that are polymorphic in humans and different among ethnic groups. The aims of this study were to estimate the frequencies of the TSER variants in two hospital samples located in the northern (HSJ) and eastern (CLC) parts of Santiago, Chile, and compare them with the frequencies in other populations of different ethnic origin.

METHODS

Genotyping of TSER variants in 368 Chilean subjects (HSJ = 178 and CLC = 190) by polymerase chain reaction; products of amplification were electrophoresed, obtaining fragments of 250 bp for allele TSER*3 and 220 bp for allele TSER*2.

RESULTS

The two hospital samples had different degrees of Amerindian admixture (HSJ 34.5%; CLC 15.9%), which was not reflected in the observed frequencies of the CLC TSER*3: 56.8% and HSJ TSER*3: 53.4%.

CONCLUSIONS

Our results are unexpected, considering that genetic markers in the Chilean population generally show allele frequencies between those observed in European Caucasians and Amerindians and that the percentage of Amerindian admixture in CLC is lower than in HSJ. Both hospitals should have had greater frequencies of TSER*3 than were found and the frequency should have been greater in HSJ than in CLC; the only logical explanation of our results is that the frequency of this allele in aboriginal Chilean people is much lower than the 80% estimated for Mongoloid populations.

DYS19 and DYS199 loci in a Chilean population of mixed ancestry

The current Chilean population originated from admixture between aboriginal populations (Amerindians) and Spanish conquerors of European origin. Consequently, the unions that gave rise to the Chilean population were chiefly between Spanish males and aboriginal females, and not the converse. To test the hypothesis that the Y chromosome of the Chilean population is mainly of Spanish origin, while the other chromosomes are from mixed (European and aboriginal) origin, we studied the DYS19 and DYS199 loci in two samples. One sample was obtained from a high socioeconomic stratum, while a second sample was from a low stratum. We studied male blood donors (N = 187) from Santiago, the capital of the country. Subjects were typed for the autosomal ABO and Rh (locus D) blood groups, and for the Y-linked DYS19 and the DYS199 loci, reported as Y-chromosome haplotypes. The aboriginal admixture was estimated for each genetic marker. The percentage of aboriginal admixture was 38.17% for the ABO system and 31.28% for the Rh system in the low socioeconomic stratum and 19.22% and 22.5%, respectively, in the high stratum. Y-chromosome haplotype frequencies constructed from the DYS19 and DYS199 loci demonstrated that the main haplotypes were DYS19*14/DYS199 C, as is often the case with many European populations, and DYS19*13/DYS199 C. The aboriginal admixture from Y-haplotype frequencies was estimated to be 15.83% in the low socioeconomic stratum and 6.91% in the high stratum. These values are lower than the values found using autosomal genetic markers, and are consistent with the historical background of the population studied. This study highlights the population genetic consequences of the asymmetric pattern of genome admixture between two ancestral populations (European and Amerindian).