Light-stimulated insulin secretion from pancreatic islet-like organoids derived from human pluripotent stem cells.

Optogenetic techniques permit non-invasive, spatiotemporal, and reversible modulation of cellular activities. Here, we report a novel optogenetic regulatory system for insulin secretion in human pluripotent stem cell (hPSC)-derived pancreatic islet-like organoids using monSTIM1 (monster-opto-Stromal interaction molecule 1), an ultra-light-sensitive OptoSTIM1 variant. The monSTIM1 transgene was incorporated at the AAVS1 locus in human embryonic stem cells (hESCs) by CRISPR-Cas9-mediated genome editing. Not only were we able to elicit light-induced intracellular Ca2+ concentration ([Ca2+]i) transients from the resulting homozygous monSTIM1+/+-hESCs, but we also successfully differentiated them into pancreatic islet-like organoids (PIOs). Upon light stimulation, the ß-cells in these monSTIM1+/+-PIOs displayed reversible and reproducible [Ca2+]i transient dynamics. Furthermore, in response to photoexcitation, they secreted human insulin. Light-responsive insulin secretion was similarly observed in monSTIM1+/+-PIOs produced from neonatal diabetes (ND) patient-derived induced pluripotent stem cells (iPSCs). Under LED illumination, monSTIM1+/+-PIO-transplanted diabetic mice produced human c-peptide. Collectively, we developed a cellular model for the optogenetic control of insulin secretion using hPSCs, with the potential to be applied to the amelioration of hyperglycemic disorders.

MHC Class I Enables MSCs to Evade NK-Cell-Mediated Cytotoxicity and Exert Immunosuppressive Activity.

Allogeneic mesenchymal stem/stromal cells (MSCs) are frequently used in clinical trials due to their low expression of major histocompatibility complex (MHC) class I and lack of MHC class II. However, the levels of MHC classes I and II in MSCs are increased by inflammatory stimuli, raising concerns over potential adverse effects associated with allogeneic cell therapy. Also, it is unclear how the host immune response to MHC-mismatched MSCs affects the therapeutic efficacy of the cells. Herein, using strategies to manipulate MHC genes in human bone marrow-derived MSCs via the CRISPR-Cas9 system, plasmids, or siRNAs, we found that inhibition of MHC class I-not MHC class II-in MSCs lowered the survival rate of MSCs and their immunosuppressive potency in mice with experimental autoimmune uveoretinitis, specifically by increasing MSC vulnerability to natural killer (NK)-cell-mediated cytotoxicity. A subsequent survey of MSC batches derived from 6 human donors confirmed a significant correlation between MSC survival rate and susceptibility to NK cells with the potency of MSCs to increase MHC class I level upon stimulation. Our overall results demonstrate that MHC class I enables MSCs to evade NK-cell-mediated cytotoxicity and exert immunosuppressive activity.

Efficacy of Smart Speaker-Based Metamemory Training in Older Adults: Case-Control Cohort Study.

BACKGROUND: Metamemory training (MMT) is a useful training strategy for improving cognitive functioning in the older adult population. Despite the advantages, there are limitations imposed by location and time constraints. OBJECTIVE: This study aimed to develop a smart speaker-based MMT program and evaluate the efficacy of the program in older adults without cognitive impairment. METHODS: This study used a case-control cohort design. The smart speaker-based MMT program comprised 3 training sessions per day, 5 days a week, for 8 weeks. Each training session took approximately 15 minutes. This program was implemented using smart speakers, not human trainers. All participants completed the Mini-Mental State Examination, Subjective Memory Complaints Questionnaire, Verbal Learning Test, Digit Span Test, fluency tests, and a short-form version of the Geriatric Depression Scale before and after training. RESULTS: A total of 60 subjects (29 in the MMT group and 31 in the control group) participated in the study. The training group showed significant increases in the delayed free recall, digit span forward, digit span backward, and fluency test scores compared with the control group. CONCLUSIONS: This study confirmed the efficacy of smart speaker-based MMT in older adults. Home-based smart speaker-based MMT is not limited with respect to location or constrained by space and may help older adults with subjective cognitive decline without requiring intervention by human professionals.

Bariatric Arterial Embolization with Calibrated Radiopaque Microspheres and an Antireflux Catheter Suppresses Weight Gain and Appetite-Stimulating Hormones in Swine.

PURPOSE: To examine safety and efficacy of bariatric arterial embolization (BAE) with x-ray-visible embolic microspheres (XEMs) and an antireflux catheter in swine. MATERIAL AND METHODS: BAE with selective infusion of XEMs (n = 6) or saline (n = 4, control) into gastric fundal arteries was performed under x-ray guidance. Weight and plasma hormone levels were measured at baseline and weekly for 4 weeks after embolization. Cone-beam CT images were acquired immediately after embolization and weekly for 4 weeks. Hormone-expressing cells in the stomach were assessed by immunohistochemical staining. RESULTS: BAE pigs lost weight 1 week after embolization followed by significantly impaired weight gain relative to control animals (14.3% vs 20.9% at 4 weeks, P = .03). Plasma ghrelin levels were significantly lower in BAE pigs than in control animals (1,221.6 pg/mL vs 1,706.2 pg/mL at 4 weeks, P < .01). XEMs were visible on x-ray and cone-beam CT during embolization, and radiopacity persisted over 4 weeks (165.5 HU at week 1 vs 158.5 HU at week 4, P = .9). Superficial mucosal ulcerations were noted in 1 of 6 BAE animals. Ghrelin-expressing cell counts were significantly lower in the gastric fundus (17.7 vs 36.8, P < .00001) and antrum (24.2 vs 46.3, P < .0001) of BAE pigs compared with control animals. Gastrin-expressing cell counts were markedly reduced in BAE pigs relative to control animals (98.5 vs 127.0, P < .02). Trichrome staining demonstrated significantly more fibrosis in BAE animals compared with control animals (13.8% vs 8.7%, P < .0001). CONCLUSIONS: XEMs enabled direct visualization of embolic material during and after embolization. BAE with XEMs and antireflux microcatheters was safe and effective.

Single-molecule DNA visualization using AT-specific red and non-specific green DNA-binding fluorescent proteins.

The recent advances in the single cell genome analysis are generating a considerable amount of novel insights into complex biological systems. However, there are still technical challenges because each cell has a single copy of DNA to be amplified in most single cell genome analytical methods. In this paper, we present a novel approach to directly visualize a genomic map on a large DNA molecule instantly stained with red and green DNA-binding fluorescent proteins without DNA amplification. For this visualization, we constructed a few types of fluorescent protein-fused DNA-binding proteins: H-NS (histone-like nucleoid-structuring protein), DNA-binding domain of BRCA1 (breast cancer 1), high mobility group-1 (HMG), and lysine tryptophan (KW) repeat motif. Because H-NS and HMG preferentially bind A/T-rich regions, we combined A/T specific binder (H-NS-mCherry and HMG-mCherry as red color) and a non-specific complementary DNA binder (BRCA1-eGFP and 2(KW)2-eGFP repeat as green color) to produce a sequence-specific two-color DNA physical map for efficient optical identification of single DNA molecules.

Hot Water Extract of Loliolus beka Meat Attenuates H2O2-Induced Damage in Human Umbilical Vein Endothelial Cells.

Blood vessels become less flexible with senescence; arteries narrow and become less flexible, disturbing blood circulation in aging and other vascular diseases. Mechanistically, vascular senescence plays an important role in the pathogenesis of normal aging and age-related vascular diseases. Vascular senescence also causes vascular dysfunction, resulting in damage to the vessel wall. Vascular aging involves the senescence of endothelial cells. Hydrogen peroxide is widely used to achieve oxidative stress-induced premature senescence. Here, we investigated the protective effects of a hot water extract of Loliolus beka meat (LBM) against H2O2-exposed HUVECs, a human umbilical vein endothelial cells line. The hot water extract of LBM protected cells against H2O2-induced cytotoxicity while reducing the expression of senescence markers, including ß-galactosidase, p53, and p21. In addition, the hot water extract of LBM protected against H2O2-induced DNA damage. These findings suggest that the hot water extract of LBM protects HUVECs from H2O2-induced senescence by preventing cellular damage. LBM serve as a supplement or natural food with benefits against vascular disease.

Protective Effect of Hot Water Extract of Loliolus Beka Gray Meat Against Palmitate-Induced HUVEC Damage.

Endothelial dysfunction is a critical factor in the development of diabetes-mediated cardiovascular complications. Free fatty acids (FFA), such as palmitate, which are elevated in diabetes and obesity, have been shown to mediate endothelial dysfunction, perhaps related to oxidative stress and inflammation. Taurine ameliorates endothelial dysfunction induced by diabetes. However, there has been no reports on the effect of Loliolus beka gray meat extracts, which contain large amounts of taurine. Here, we investigated the protective effect of a hot water extract of Loliolus beka gray meat (LBM), on palmitate-induced cell damage in human umbilical vein endothelial cells (HUVEC). The LBM extract was found to inhibit palmitate-induced cytotoxicity and DNA damage. In addition, the LBM extract reduced the level of reactive oxygen species (ROS) and nitric oxide (NO), as well as pro-inflammatory cytokines in HUVEC. These results suggest that the LBM extract protects against palmitate-induced cytotoxicity in HUVECs. Therefore, potential therapeutic and/or inhibitors of vascular disease may be derived from the LBM extract.

A Hepatoprotective Effect of a Hot Water Extract from Loliolus beka Gray Meat Against H2O2-Induced Oxidative Damage in Hepatocytes.

Here, we investigated the hepatoprotective effect of a hot water extract from Loliolus beka gray meat (LBMH) containing plentiful taurine in H2O2-induced oxidative stress in hepatocytes. LBMH potently scavenged the 2,2-azino-bis(3-ethylbenzthiazoline)-6-sulfonic acid (ABTS) and 2,2-diphenyl-1-picrylhydrazyl (DPPH) radicals and exhibited the good reducing power and the oxygen radical absorbance capacity (ORAC) value. Also, LBMH improved the cell viability against H2O2-induced hepatic damage in cultured hepatocytes by reducing intracellular reactive oxygen species (ROS) production. In addition, LBMH inhibited apoptosis via a reduction in sub-G1 cell population, as well as inhibition of apoptotic body formation from H2O2-induced oxidative damage in hepatocytes. Moreover, LBMH regulated the expression levels of Bax, a pro-apoptotic molecule and Bcl-2, an anti-apoptotic molecule in H2O2-treated hepatocytes. Additionally, pre-treatment with LBMH increased the expression of heme oxygenase 1 (HO-1), which is a hepatoprotective enzyme, by activating the nuclear factor erythroid 2-related factor 2 (Nrf2) in H2O2-treated hepatocytes. Taken together, LBMH may be useful as a food ingredient for treatment of liver disease by regulating the Nrf2/HO-1 signal pathway.

An Aqueous Extract from Batillus Cornutus Meat Protects Against H2O2-Mediated Cellular Damage via Up-Regulation of Nrf2/HO-1 Signal Pathway in Chang Cells.

In this study, we evaluated the protective effects of an aqueous extract from Batillus cornutus meat (BM) against cellular oxidative damage caused by hydrogen peroxide (H2O2) in human hepatocyte, Chang cells. First, we prepared an aqueous extract of BM meat (BMW) showing the highest taurine content among free amino acid contents. BMW led to high antioxidant activity showing 2,2-azino-bis(3-ethylbenzthiazoline)-6-sulfonic acid (ABTS) radical scavenging activity, good reducing power and an oxygen radical absorbance capacity (ORAC) value. Also, BMW improved cell viability that was diminished by H2O2 exposure, as it reduced the generation of intracellular reactive oxygen species (ROS) in Chang cells. In addition, BMW up-regulated the production of antioxidant enzymes, such as catalase and superoxide dismutase (SOD), compared to H2O2-treated Chang cells lacking BMW. Moreover, BMW induced the expressions of nuclear Nrf2 and cytosolic HO-1 in H2O2-treated Chang cells. Interestingly, the treatment of ZnPP, HO-1 inhibitor, abolished the improvement in cell viability and intracellular ROS generation mediated by BMW treatment. In conclusion, this study suggests that BMW protects hepatocytes against H2O2-mediated cellular oxidative damage via up-regulation of the Nrf2/HO-1 signal pathway.

An Aqueous Extract of Octopus ocellatus Meat Protects Hepatocytes Against H2O2-Induced Oxidative Stress via the Regulation of Bcl-2/Bax Signaling.

Octopus ocellatus meat (OM) is well known as a plentiful protein source. In this study, we evaluated the hepatoprotective effect of an aqueous extract of OM (OMA) against H2O2-triggered oxidative stress in human hepatocytes. First of all, taurine rich OMA showed a good ORAC value and reducing power and it was similar with that of ascorbic acid, which is known as a strong antioxidant. Also, OMA significantly improved H2O2-decreased cell viability by reducing the generation of intracellular reactive oxygen species (ROS) in hepatocytes. Interestingly, the stimulation of H2O2-induced the formations of apoptotic bodies and sub-G1 DNA content, whereas they were inhibited by the treatment with OMA. Furthermore, OMA regulated the protein expression levels of apoptotic molecules, such as Bax and Bcl-2. Taken together, this study suggests that OMA, which contains an abundant amount of taurine, protects hepatocytes from H2O2-triggered oxidative stress and might be a functional food material with hepatoprotective effects.

Antioxidant Effects of an Alcalase Hydrolysate from Batillus cornutus Meat.

Batillus cornutus (B. cornutus) is one of the gastropoda, which are distributed along the coast of China, Japan and South Korea and northeast area. In this study, we first identified the antioxidant effects of a B. cornutus meat (BM) enzymatic hydrolysate in H2O2-treated Vero cells. First of all, we prepared an Alcalase hydrolysate from BM (BMA) and revealed a high taurine content. Also, taurine rich BMA dose-dependently increased 2,2-azino-bis(3-ethylbenzthiazoline)-6-sulfonic acid (ABTS) radical scavenging activity, reducing power and the higher oxygen radical absorbance capacity (ORAC) value. In addition, BMA significantly increased the cell viability via the down-regulation of intracellular reactive oxygen species (ROS) production, as well as the decreased formation of apoptotic bodies and sub-G1 DNA population in H2O2-treated Vero cells. Furthermore, BMA increased the expression of the anti-apoptotic molecule, Bcl-2, and decreased the expressions of Bax, p53 and cleaved PARP, all of which are pro-apoptotic molecules, in H2O2-treated Vero cells. Based on these results, this study suggests that BMA may be used as a potential protector on damage caused by oxidative stress.

Cytoprotective Effects of an Aqueous Extracts from Atrina Pectinate Meat in H2O2-Induced Oxidative Stress in a Human Hepatocyte.

In the present study, we investigated the antioxidant activity of an aqueous extract from Atrina pectinate meat (APW) against H2O2-induced oxidative stress in a human hepatocyte. The extraction yield of APW was 30.01 ± 0.83% and which contained the highest taurine content among free amino acid contents. APW led to the high antioxidant activity showing 2,2-azino-bis(3-ethylbenzthiazoline)-6-sulfonic acid (ABTS) radical scavenging activity, good reducing power and oxygen radical absorbance capacity (ORAC) value. Also, the results showed that APW improved the cell viability decreased by H2O2 stimulation as well as the reduction of intracellular reactive oxygen species (ROS) generation in hepatocytes. Additionally, APW up-regulated the production of antioxidant mechanisms related enzymes such as catalase and superoxide dismutase (SOD), compared to the only H2O2-treated hepatocytes. Moreover, APW increased the expressions of nuclear Nrf2 and cytosolic HO-1 in H2O2-treated hepatocytes. Interestingly, the treatment of ZnPP, a HO-1 inhibitor abolished the cell viability and intracellular ROS generation induced by APW treatment. In conclusion, this study suggests that APW protects H2O2 induced oxidative stress via up-regulating of Nrf2/HO-1 signal pathway in hepatocytes.

Hepatoprotective Activity of a Taurine-Rich Water Soluble Extract from Octopus vulgaris Meat.

In this study, we investigated the hepatoprotective activity of the water extract derived from Octopus vulgaris meat (OM). First of all, a water extract prepared from OM (OMW) showed the high extraction yield (48.22%) and the highest taurine content (39.84%) in free amino acids. OMW exhibited the high value of reducing power, ABTS and hydrogen peroxide radical scavenging activities in dose-dependent manner. The taurine-rich OMW also led to the reduced intracellular reactive oxygen species (ROS) generation with the increased cell survival in H2O2-treated Chang liver cells. In addition, OMW decreased the apoptotic phenomenon, including the formations of apoptotic bodies and sub-G1 DNA contents by regulating the protein expressions of apoptosis-related molecules such as Bcl-2 and Bax. From these results, this study indicated the taurine-rich OMW protected hepatocytes against oxidative stress. These findings suggest that OWM may be a novel potential antioxidant resource.

Radio-Protective Effects of Loliolus beka Gray Meat Consisted of a Plentiful Taurine Against Damages Caused by Gamma Ray Irradiation.

Gamma ray irradiation causes immune suppression, in which oxidative stress reduces cell viability and damages immune cells. In the present study, we investigated whether Loliolus beka gray meat (LBM), which contains large amounts of taurine, protects against damage of murine splenocytes by oxidative stress. An aqueous extract of LBM (LBMW) was prepared, which contained plentiful levels of taurine. LBMW improved cell viability of gamma ray-irradiated murine splenocytes, an effect that was associated with significant reduction in the production of reactive oxygen species (ROS). We also showed that the production of nitric oxide (NO) and ROS in gamma ray-irradiated zebrafish embryos, as well as the death of the embryos, were diminished by LBMW. These data suggest that the consumption of taurine-rich foods, such as LBM, may be used in the protection of cells against oxidative stress.

Potential Photoprotective Effect of Dietary Corn Silk Extract on Ultraviolet B-Induced Skin Damage.

Ultraviolet B (UVB) irradiation causes adverse effects on the skin. Corn silk contains flavonoids and other bioactive compounds and antioxidants, which may prevent skin photoaging through antioxidant and anti-inflammatory effects. We aimed to investigate the potential photoprotective effects of dietary corn silk on UVB-induced skin damage in mice and the mechanisms behind these effects on human skin cells. Oral administration of corn silk water extract (CS) (2 or 4 g/kg/day) for 19 weeks decreased epidermal thickness, wrinkle formation, and positive staining for PCNA, Ki67, and 8-OHdG, and increased collagen staining in UVB-irradiated SKH-1 hairless mice compared with controls. The pro-inflammatory NF-κB target genes (IL-1ß, iNOS, and COX-2) and MMP-9 expressions were lower in the CS groups, and TGF-ß/Smad signaling increased. Low skin lipid peroxidation and blood DNA oxidation levels and high blood glutathione were detected. Antioxidant transcription factor Nrf2-related catalase and SOD1 proteins and glutaredoxin mRNA levels increased. The results of CS extract treatment and UVB irradiation in HaCaT cells showed the same results in Nrf2 and NF-κB target genes. An LC-MS/MS analysis showed that the CS extract contained potential antioxidants, which might have contributed to its anti-photoaging effects in tissues and cells. CS extract may reduce UVB-induced skin damage through antioxidant and anti-inflammatory mechanisms.

Bariatric Arterial Embolization: Effect of Microsphere Size on the Suppression of Fundal Ghrelin Expression and Weight Change in a Swine Model.

Purpose To determine whether microsphere size effects ghrelin expression and weight gain after selective bariatric arterial embolization (BAE) in swine. Materials and Methods BAE was performed in 10 swine by using smaller (100-300 µm; n = 5) or larger (300-500 µm; n = 5) calibrated microspheres into gastric arteries. Nine control pigs underwent a sham procedure. Weight and fasting plasma ghrelin levels were measured at baseline and weekly for 16 weeks. Ghrelin-expressing cells (GECs) in the stomach were assessed by using immunohistochemical staining and analyzed by using the Wilcoxon rank-sum test. Results In pigs treated with smaller microspheres, mean weight gain at 16 weeks (106.9% ± 15.0) was less than in control pigs (131.9% ± 11.6) (P < .001). Mean GEC density was lower in the gastric fundus (14.8 ± 6.3 vs 25.0 ± 6.9, P < .001) and body (27.5 ± 12.3 vs 37.9 ± 11.8, P = .004) but was not significantly different in the gastric antrum (28.2 ± 16.3 vs 24.3 ± 11.6, P = .84) and duodenum (9.2 ± 3.8 vs 8.7 ± 2.9, P = .66) versus in control pigs. BAE with larger microspheres failed to suppress weight gain or GECs in any stomach part compared with results in control swine. Plasma ghrelin levels were similar between BAE pigs and control pigs, regardless of microsphere size. Week 1 endoscopic evaluation for gastric ulcers revealed none in control pigs, five ulcers in five pigs embolized by using smaller microspheres, and three ulcers in five pigs embolized by using larger microspheres. Conclusion In bariatric arterial embolization, smaller microspheres rather than larger microspheres showed greater weight gain suppression and fundal ghrelin expression with more gastric ulceration in a swine model. © RSNA, 2018.

Using an endoscopic distal cap to collect pancreatic fluid from the ampulla (with video).

BACKGROUND AND AIMS: Duodenal collections of pancreatic fluid can be used as a source of mutations and other markers of pancreatic ductal neoplasia, but admixing pancreatic juice with duodenal contents lowers the concentrations of mutations. Collecting pancreatic fluid directly from the ampulla could yield a purer sample of pancreatic fluid. METHODS: We used an endoscopic distal cap attachment to "cap" the ampulla and collect secretin-stimulated pancreatic fluid samples for 5 minutes from 81 patients undergoing pancreatic evaluation as part of the Cancer of the Pancreas Screening studies. We compared mutation concentrations (K-ras and GNAS) measured by droplet-digital PCR (ddPCR) in "cap-collected juice" samples to those found in juice samples obtained from 77 patients collected by aspiration from the duodenal lumen without capping the ampulla. RESULTS: Among all subjects, mutation concentrations were higher in pancreatic juice samples collected using the endoscopic cap method (median, .028%; IQR, 0-.077) compared with the noncap-collected (median, .019%; IQR, 0-.044; P = .055). Among pancreatic juice samples with detectable mutations, mutation concentrations were higher in the cap-collected juice samples than in those collected without the cap (.055%; IQR, .026-.092 vs .032%; IQR, .020-.066; P = .031). CONCLUSIONS: Collecting pancreatic juice directly from the ampulla using an endoscopic distal cap yields higher concentrations of pancreatic fluid mutations.

Anti-obesity potential of enzymatic fragments of hyaluronan on high-fat diet-induced obesity in C57BL/6 mice.

Hyaluronan has diverse biological activities depending on its molecular size. The hyaluronan fragments (50 kDa) can decrease adipogenic differentiation in vitro. However, in vivo anti-obesitic effects of hyaluronan fragments have not been elucidated. Therefore, we examined the anti-obesity effects of hyaluronan fragments on high-fat diet induced obesity in C57BL/6 mice. Oral administration of hyaluronan fragments (200 mg/kg for 8 weeks) decreased body weight, adipose tissues, serum lipid (low-density lipoprotein cholesterol, triglyceride), and leptin level. Hyaluronan fragments decreased the hypertrophy of adipose tissue and ameliorated liver steatosis. The mRNA expression of leptin was reduced in adipocyte by treatment with hyaluronan fragments. Additionally, hyaluronan fragments enhanced the mRNA expression of PPAR-α and its target genes UCP-2 and decreased mRNA expression of PPAR- γ and fatty acid synthase in liver. In conclusions, hyaluronan fragments had marked effects on inhibiting the development of obesity in obese mice fed the high-fat diet. It suggested that enhancing PPAR-α and suppressing PPAR-γ expression are two possible mechanisms for the anti-obesitic effect of hyaluronan fragments.

Analysis of walker-aided walking by the healthy elderly with a walker pocket of different weights attached at different locations.

[Purpose] This study aims to provide information on safe walker-aided walking by analyzing elderly subjects' walking with a walker pocket of different weights attached at different locations. [Subjects and Methods] Twenty elderly right-handed males participated in the study, and a walking analyzer was used to examine their walking with a pocket attached to the left, center, and right side of the walker. The weight of the pocket was set at three levels relative to the average weight of the subject group: 0% (without pocket), 2.5% (2 kg), and 5.5% (4 kg). [Results] In terms of the pocket location, step width was the narrowest when the pocket was attached to the right side, while the other elements of walking did not change. In terms of the pocket weight, all elements of walking showed changes. A heavier pocket led to a shorter step length and stride, a greater step width, and longer time. [Conclusion] When elderly people use a pocket-attached walker, the pocket is recommended to be attached to the right side of the walker, and its weight should be kept under 5.5% of the user's weight to ensure safe walking.

Gender-based analysis of muscle activation while in a sedentary work posture.

BACKGROUND: Many people work in a sitting position where they have to use their upper extremities and hands. Muscle activity in sitting position is affected by the chair height of, the height of the worktable, and the distance to the working target. OBJECTIVE: The purpose of this study is to investigate differences in muscle activity between men and wemen at different chair heghts and working distances. METHODS: Surface electromyography (EMG) was employed to determine the muscle activity of the upper limbs and the trunk, while an arm-stretching task was performed in a sitting position. RESULTS: Women's muscle activity was higher than that of men in most muscles as the chair height and working distance changed. CONCLUSIONS: As the height of the chair or the working distance was changed, muscle activity was greater in women than in men for most of the muscles analyzed. Under the same conditions, women may feel more muscle fatigue than men, so it is necessary to consider gender in the working environment.