Gary A. Wittert

JMIR research protocols • April 15, 2025

Phillip Tully, Suzanne Cosh, Gary Wittert, Sean Martin, Andrew Vincent, Antonina Mikocka Walus, Deborah Turnbull

Background: Long occupational working hours and shift work are common in high, middle, and lower-income economies. Bowel movement frequency and stool form in occupational settings may be important markers of stressful working conditions as well as diurnal gut microbiota action, gastrointestinal discomfort, and disorders of gut-brain interaction (DGBI). Characterizing DGBI in shift and non-shift workers could help identify the impact of diurnal work patterns on worker's physical and mental health, including anxiety related to bowel movements. Objective: The paper outlines the Insight inTo Stress and POOping on work TIME (ITS POO TIME) protocol describing a web-based multi-methods research project on DGBI, stool form and frequency, psychological factors, sleep, diet and anxiety related to bowel movements in occupational settings by comparison to residential settings. Methods: Study 1 comprises a web-based convenience sampling survey to acquire quantitative data from adults who are engaged in paid employment. We seek to assess occupational characteristics, organizational factors, as well as standardized questionnaires for stool form, DGBI assessed by Rome-IV criteria, sleep, diet, bowel movement anxiety (i.e. parcopresis), and distress. Study 2 is a qualitative study which asks open-ended questions about respondents' attitudes to defecation at work. Analyses for Study 1 will explore rates of DGBI in shift vs. non-shift workers and explore how occupational characteristics are associated with occupational bowel movement stool form and frequency. With regards to distress, and parcopresis, Study 1 will analyse how parcopresis, distress, and contamination fears are associated with stool form and frequency in occupational settings compared with residential settings. Study 1 is designed to have 90% power to detect a 5% difference in DGBI prevalence between groups at α = 0.05 based on the conservative estimate of 15% DGBI prevalence in shift workers and 10% DGBI prevalence in non-shift workers, with a final sample of N=1967 required. Study 2 qualitative data will be analysed using inductive thematic analysis to identify themes concerning feelings and attitudes about bowel movements in occupational settings. Results: The findings of ITS POO TIME will elicit important information on what factors are associated with bowel movements and stool form and frequency in occupational settings and identify associations pertinent to occupational health. Data collection commenced in January 2019 and finished enrolment in December 2023. Study 1 obtained 1872 responses and fell short of the desired sample size. Study 2 received 337 responses, and the primary results are expected to be published in 2025 and qualitative results published in 2026. Conclusions: The results of the research described in this research protocol will have direct implications for industry, employers, and policy makers concerning DGBI, stress, and worker health. Background: null

Nutrition Research (New York, N.Y.) • December 22, 2024

You Chang, Laurent Turner, Xiao Teong, Lijun Zhao, Athena Variji, Gary Wittert, Sophia Thompkins, Andrew Vincent, Linda Grosser, Morag Young, Stephen Blake, Satchidananda Panda, Emily N Manoogian, Siobhan Banks, Leonie Heilbronn, Amy Hutchison

Time-restricted eating (TRE) may extend the cardiometabolic health benefits of calorie restriction (CR). However, few studies have compared its effect on the circadian regulation of glucose metabolism and the optimal time of day to initiate TRE is also unclear. This study aims to compare the effectiveness of CR with and without TRE on glucose tolerance in response to 3 identical meals consumed over the day. A parallel, single-blinded, 3-arm randomised controlled trial will be conducted in 114 adults, aged 35 to 75 years with a BMI ≥25.1 but <45.0 kg/m2, elevated waist circumference and fasting blood glucose (≥5.6 mmol/L), and who score ≥12 on the Australian Type 2 Diabetes Risk Assessment tool. Participants will be stratified by sex and fasting blood glucose (≤6.0 mmol/L; >6.0 mmol/L) and then randomised (1:1:1) to CR (unrestricted meal timing), eCR (0800 to 1600) or dCR (1200-2000) for 8 weeks. The primary outcome is the change in the natural logarithm of the mean over 3 identical meals of the postprandial glucose area under the curve (AUC). The analysis will be performed using a covariate adjusted linear regression of the differences in postprandial glucose log AUC at 8 weeks from baseline. This randomised clinical trial will be the first to delineate the benefits of CR alone or in combination with time restricted eating on postprandial glucose metabolism over the day in adults at increased risk of type 2 diabetes.

The Journal Of Clinical Endocrinology And Metabolism • December 21, 2024

Christopher Muir, Gary Wittert, David Handelsman

Pathologic hypogonadism occurs when serum testosterone is significantly and persistently reduced by irreversible organic (structural, genetic) disorders of the hypothalamic pituitary testicular (HPT) axis. Men with pathologic hypogonadism require life-long testosterone replacement. In contrast, mild or moderate reductions in serum testosterone frequently accompany obesity and its numerous co-morbidities in men and are best considered as non-gonadal illness syndromes, wherein reduction in serum testosterone is usually reversible upon amelioration of the underlying non-gonadal illness. Obesity can result in non-specific symptoms in conjunction with reduced serum testosterone and serum SHBG. Obesity-related reductions in SHBG, testosterone's principal circulating carrier protein, are primarily responsible for measured reductions in testosterone. However, obesity is not a cause of pathological hypogonadism and proportionately reduced testosterone and SHBG concentrations accompanied by normal serum LH and FSH concentrations confirm a eugonadal state, best described as the pseudo-hypogonadism of obesity. Herein we demonstrate how clinically significant weight loss substantially reverses obesity-related reductions in serum testosterone and ameliorates non-specific symptoms resembling, but not due to, androgen deficiency. The important reversible steps include weight reduction, optimizing management of type 2 diabetes mellitus, obstructive sleep apnea, depression and other obesity related co-morbidities as well as rationalizing concomitant drug regimens. In the absence of pathological hypogonadism, testosterone treatment is less effective than a diet and lifestyle intervention to rectify the reversible conditions responsible for the non-specific symptoms and associated reduced serum testosterone concentrations observed in men with obesity. As such, testosterone treatment is not indicated and unwarranted off-label testosterone treatment can lead to adverse effects such as infertility, elevated hematocrit requiring venesection, a prothrombotic state and testosterone dependence.

PloS One • October 24, 2024

Melinda Tursky, Crisbel Artuz, Melissa Rapadas, Gary Wittert, Timothy Molloy, David Ma

Clonal haematopoiesis of indeterminate potential (CHIP) is an aging-associated phenomenon that has recently been correlated with a broad spectrum of human diseases, including haematological malignancy, cytopenia, coronary heart disease, stroke, and overall mortality. CHIP is defined as a somatic variant in blood cells with an allele frequency (VAF) ≥ 0.02, however recent reports show smaller clones are associated with poorer clinical outcome. Error-corrected ultradeep next-generation sequencing (NGS) assays detecting variants < 0.02 VAF also have clinical value for monitoring measurable residual disease (MRD) for myeloid neoplasms. However, limited data are available on optimal parameters, limits of detection, and accuracy of ultra-sensitive detection. We investigated parameters to improve accuracy of Illumina sequencing-by-synthesis method, including read depth, input DNA quantity, and molecular barcoding-based data filtering, while adhering to clinical accreditation criteria. Validation data were generated from reference standards and reference samples from a clinically accredited pathology laboratory. Analytical range measurements included linearity and bias, and precision included repeatability, reproducibility and detection rate. The lower limit of detection was ≥ 0.004 (0.4%) at depth > 3,000 × . Trueness measured using reference standards demonstrated a sensitivity, specificity, positive and negative predictive values, and accuracy of 100%, including FLT3-ITD, and 100% concordance was achieved with reference samples for reported variants and absence of variants. Sequencing blood samples from 383 community-dwelling adults (mean depth 3758×) revealed 2,190 somatic variants/sample, > 99.9% were < 0.02 VAF. Our data including cost-benefit analysis enables pathology and research laboratories to make informed decisions for detection of CHIP (VAF ≥ 0.02), sub-CHIP (VAF 0.01-0.02) and MRD (VAF ≥ 0.004).

The Journal Of Physiology • October 22, 2024

Julien Bensalem, Xiao Teong, Kathryn Hattersley, Leanne Hein, Célia Fourrier, Linh Dang, Sanjna Singh, Kai Liu, Gary Wittert, Amy Hutchison, Leonie Heilbronn, Timothy Sargeant

Autophagy slows age-related pathologies and is stimulated by nutrient restriction in animal studies. However, this has never been shown in humans. We measured autophagy using a physiologically relevant measure of autophagic flux (flux of MAP1LC3B isoform II/LC3B-II in peripheral blood mononuclear cells in the context of whole blood) in 121 humans with obesity who were randomised to standard care (SC, control condition), calorie restriction (CR) or intermittent fasting plus time-restricted eating (iTRE) for 6 months. While the differences in change from baseline between groups was not significant at 2 months, we observed a significant difference in change from baseline between iTRE compared to SC at 6 months (P = 0.04, post hoc analysis). This effect may be driven partly by a tendency for autophagy to decrease in the SC group. The difference in change from baseline between CR and SC was not significant. Uncorrected analysis of correlations showed a negative relationship between change in autophagy and change in blood triglycerides. Data on the specificity and performance of the methods used to measure human autophagy are also presented. This shows autophagy may be increased by intermittent nutrient restriction in humans. If so, this is a demonstration that nutrient restriction can be used to improve a primary hallmark of biological ageing and provides a mechanism for how fasting could delay the onset of age-related disease. KEY POINTS: Autophagy slows biological ageing, and dysfunction of autophagy has been implicated in age-related disease - an effective way of increasing autophagy in cells and animal models is nutrient restriction. However, the impact of different types of nutrient restriction on physiological autophagic flux in humans has not been extensively researched. Here we measure the effect of intermittent time-restricted eating (iTRE) and calorie restriction on physiological autophagic flux in peripheral blood mononuclear cells. After 6 months, there was a significant difference in change from baseline between the iTRE and the standard care control group, with flux being higher in the iTRE group at this timepoint. However, there was no significant increase from baseline within the iTRE group, showing that although autophagy may be modified by nutrient restriction in humans, further studies are required.