Impact of the COVID-19 pandemic on clinical and psychological aspects of temporomandibular disorders

BACKGROUND

The Coronavirus 2019 disease (COVID-19) caused drastic changes in people's lifestyle that affected TMD characteristics through its physical and psychological influences. The aim of this study was to define the clinical and psychological characteristics of a large group of well-defined TMD patients and seek their differences between before and during the COVID-19 pandemic to establish points of care to be emphasized in the post-pandemic era.

METHODS

TMD patients diagnosed by the Diagnostic Criteria for Temporomandibular Disorders (DC/TMD) aged ≥ 18 were analyzed. Samples between September, 2017 to July, 2019 (n = 455) and March, 2021 to June, 2022 (n = 338) were collected to represent before and during COVID-19, respectively. The Graded Chronic Pain Scale (GCPS) and Symptom Checklist-90-Revision (SCL-90-R) were used to evaluate disability levels and psychological status. Clinical indices were compared between COVID periods and factors related to higher pain levels were investigated according to pandemic period.

RESULTS

More patients reported pain on palpation of the masticatory muscles during the pandemic (p = 0.021) while the number decreased for neck muscles (p = 0.001) and TMJ (p < 0.001) areas. Patients reporting nocturnal bruxism (23.3-29.6%) and clenching (45.1-54.7%) significantly increased during the pandemic. TMD patients with pain without disability were more common during the pandemic regardless of pain intensity (p < 0.001). The number of patients expressing interference in daily activities decreased drastically during COVID-19 regardless of disability level (p < 0.001). Factors associated with higher than moderate pain intensity (CPI ≥ 50) were insomnia (odds ratio [OR] = 1.603, p = 0.047) and somatization (OR = 1.082, p < 0.001) before the pandemic. During the pandemic, age (OR = 1.024, p = 0.007), somatization (OR = 1.070, p = 0.006), and paranoid ideation (OR = 1.117, p = 0.003) were significantly associated with higher pain intensity.

CONCLUSIONS

The results of our study underline the importance of evaluating psychological profiles of TMD patients, especially somatization, paranoid ideation and psychoticism, in exceptional situations that may cause a change in individual mental status. This will lead to a better understanding of the individual TMD patient and help in planning personalized treatment strategies that will assist the patient in adjusting to changes occurring in special environments such as the COVID-19 pandemic.

Rab25 suppresses colon cancer cell invasion through upregulating claudin‑7 expression

Ras‑related protein 25 (Rab25) is a member of small GTPase and is implicated in cancer cell progression of various types of cancer. Growing evidence suggests the context‑dependent role of Rab25 in cancer invasiveness. Claudin‑7 is a tight junction protein and has been known to suppress cancer cell invasion. Although Rab25 was reported to repress cancer aggressiveness through recycling β1 integrin to the plasma membrane, the detailed underlying mechanism remains to be elucidated. The present study identified the critical role of claudin‑7 in Rab25‑induced suppression of colon cancer invasion. 3D Matrigel system and modified Boyden chamber analysis showed that enforced expression of Rab25 attenuated colon cancer cell invasion. In addition, Rab25 inactivated epidermal growth factor receptor (EGFR) and increased E‑cadherin expression. Unexpectedly, it was observed that Rab25 induces claudin‑7 expression through protein stabilization. In addition, ectopic claudin‑7 expression reduced EGFR activity and Snail expression as well as colon cancer cell invasion. However, silencing of claudin‑7 expression reversed the tumor suppressive role of Rab25, thereby increasing colon cancer cell invasiveness. Collectively, the present data indicated that Rab25 inactivates EGFR and colon cancer cell invasion by upregulating claudin‑7 expression.

Lysophosphatidic acid-induced amphiregulin secretion by cancer-associated fibroblasts augments cancer cell invasion

Cancer-associated fibroblasts (CAFs) are key structural components of the tumor microenvironment and are closely associated with tumor invasion and metastasis. Lysophosphatidic acid (LPA) is a biolipid produced extracellularly and involved in tumorigenesis and metastasis. LPA has recently been implicated in the education and transdifferentiation of normal fibroblasts (NFs) into CAFs. However, little is known about the effects of LPA on CAFs and their participation in cancer cell invasion. In the present study, we identified a critical role of LPA-induced amphiregulin (AREG) secreted from CAFs in cancer invasiveness. CAFs secrete higher amounts of AREG than NFs, and LPA induces AREG expression in CAFs to augment their invasiveness. Strikingly, knocking out the AREG gene in CAFs attenuates cancer invasiveness and metastasis. Mechanistically, LPA induces Yes-associated protein (YAP) activation and Zinc finger E-box binding homeobox 1 (Zeb1) expression through the LPAR1 and LPAR3/Gi/Rho signaling axes, leading to AREG expression. Furthermore, we provide evidence that metformin, a biguanide derivative, significantly inhibits LPA-induced AREG expression in CAFs to attenuate cancer cell invasiveness. Collectively, the present data show that LPA induces AREG expression through YAP and Zeb1 in CAFs to promote cancer cell invasiveness, with the process being inhibited by metformin, providing potential biomarkers and therapeutic avenues to interdict cancer cell invasion.

STAT3 mediates RCP-induced cancer cell invasion through the NF-κB/Slug/MT1-MMP signaling cascade

Rab coupling protein (RCP) has been known to induce cancer invasion and metastasis, and STAT3 is one of major oncogenic factors. In the present study, we identify the critical role of STAT3 in RCP-induced cancer cell invasion. Immunohistochemical data of ovarian cancer tissues presented that levels of RCP expression are closely correlated with those of phospho-STAT3 (p-STAT3). In addition, ovarian cancer patients with high expression of both RCP and p-STAT3 had significantly lower progress-free and overall survival rates compared to those with low either RCP or p-STAT3 expression. Mechanistically, RCP induced STAT3 phosphorylation in both ovarian and breast cancer cells. Silencing or pharmacological inhibition of STAT3 significantly inhibited RCP-induced cancer cell invasion. In addition, we provide evidence that the β1 integrin/EGFR axis is important for RCP-induced STAT3 phosphorylation. Furthermore, STAT3 activated NF-κB for Slug expression that in turn upregulated MT1-MMP expression for cancer cell invasion. Collectively, our present data demonstrate that STAT3 is located downstream of the β1 integrin/EGFR axis and induces Slug and MT1-MMP expression for cancer cell invasion.

Discoidin Domain Receptor 2 Mediates Lysophosphatidic Acid-Induced Ovarian Cancer Aggressiveness

Lysophosphatidic acid (LPA), a bioactive lipid produced extracellularly by autotaxin (ATX), has been known to induce various pathophysiological events, including cancer cell invasion and metastasis. Discoidin domain receptor 2 (DDR2) expression is upregulated in ovarian cancer tissues, and is closely associated with poor clinical outcomes in ovarian cancer patients. In the present study, we determined a critical role and signaling cascade for the expression of DDR2 in LPA-induced ovarian cancer cell invasion. We also found ectopic expression of ATX or stimulation of ovarian cancer cells with LPA-induced DDR2 expression. However, the silencing of DDR2 expression significantly inhibited ATX- and LPA-induced ovarian cancer cell invasion. In addition, treatment of the cells with pharmacological inhibitors of phosphoinositide 3-kinase (PI3K), Akt, and mTOR abrogated LPA-induced DDR2 expression. Moreover, we observed that HIF-1α, located downstream of the mTOR, is implicated in LPA-induced DDR2 expression and ovarian cancer cell invasion. Finally, we provide evidence that LPA-induced HIF-1α expression mediates Twist1 expression to upregulate DDR2 expression. Collectively, the present study demonstrates that ATX, and thereby LPA, induces DDR2 expression through the activation of the PI3K/Akt/mTOR/HIF-1α/Twist1 signaling axes, aggravating ovarian cancer cell invasion.

Zeb1 for RCP-induced oral cancer cell invasion and its suppression by resveratrol

Rab coupling protein (RCP) is upregulated in head and neck squamous cell carcinoma (HNSCC) and is correlated with the progression and survival of patients. However, the role of RCP in one of the aggressive types of HNSCC, oral squamous cell carcinoma (OSCC), remains elusive. In the present study, we identified the important role of Zeb1 in RCP-induced OSCC epithelial-to-mesenchymal transition (EMT) and invasion. RCP induces Zeb1 expression, and silencing Zeb1 expression significantly inhibits RCP-induced OSCC invasion. In addition, Zeb1 upregulates MT1-MMP expression to promote OSCC EMT and invasion. Furthermore, we observed that the β1 integrin/EGFR/β-catenin signaling cascade mediates RCP-induced Zeb1 expression to promote OSCC invasion. Notably, we provide evidence that resveratrol (REV) strongly inhibits RCP-induced Zeb1 expression through blocking β1 integrin endosome recycling and EGFR activation, leading to suppression of RCP-induced OSCC invasion, demonstrating the important role of RCP in OSCC invasion and its reversion by REV. Collectively, the present study provides evidence for the first time that RCP aggravates OSCC invasion through increasing Zeb1 expression and subsequently upregulating MT1-MMP expression and that this process is reversed by REV, providing novel biomarkers and indicating the therapeutic potential of REV in OSCC.

Resveratrol, a naturally occurring compound present in grape skins, peanuts, and blueberries, reduces the ability of oral squamous cell carcinoma (OSCC) cells to spread to other parts of the body. Over half a million new cases of OSCC are diagnosed each year, and spread beyond the mouth is the most common cause of death. Hoi Young Lee at Konyang University, Daejon, Republic of Korea, and co-workers investigated whether a protein called RCP, which increases the invasiveness of many but not all types of cancer, is implicated in aggressive spread of OSCC. They found that RCP does increase the invasiveness of OSCC. Resveratrol is known to suppress the spread of many cancers, and strongly curtailed the spread of OSCC by blocking RCP activity. These results shed light on OSCC invasiveness, and offer a potential new treatment.

NADPH oxidase 4 mediates TGF-β1/Smad signaling pathway induced acute kidney injury in hypoxia

Hypoxia is an important cause of acute kidney injury (AKI) in various conditions because kidneys are one of the most susceptible organs to hypoxia. In this study, we investigated whether nicotinamide adenine dinucleotide 3-phosphate (NADPH) oxidase 4 (Nox4) plays a role in hypoxia induced AKI in a cellular and animal model. Expression of Nox4 in cultured human renal proximal tubular epithelial cells (HK-2) was significantly increased by hypoxic stimulation. TGF-β1 was endogenously secreted by hypoxic HK-2 cells. SB4315432 (a TGF-β1 receptor I inhibitor) significantly inhibited Nox4 expression in HK-2 cells through the Smad-dependent cell signaling pathway. Silencing of Nox4 using Nox4 siRNA and pharmacologic inhibition with GKT137831 (a specific Nox1/4 inhibitor) reduced the production of ROS and attenuated the apoptotic pathway. In addition, knockdown of Nox4 increased cell survival in hypoxic HK-2 cells and pretreatment with GKT137831 reproduce these results. This study demonstrates that hypoxia induces HK-2 cell apoptosis through a signaling pathway involving TGF-β1 via Smad pathway induction of Nox4-dependent ROS generation. In an ischemia/reperfusion rat model, pretreatment of GKT137831 attenuated ischemia/reperfusion induced acute kidney injury as indicated by preserved kidney function, attenuated renal structural damage and reduced apoptotic cells. Therapies targeting Nox4 may be effective against hypoxia-induced AKI.

Abstract 2860: RCP augments oral cancer cell invasion through Zeb1 and Slug expression

Background: Rab coupling protein (RCP), also called family interacting protein 1 (Rab11fip1) is a protein encoded by the RAB11FIP1 gene and has been known to augment cancer tumorigenesis, invasion, and metastasis. Recently, RCP was reported to aggravate cancer cell invasion and metastasis by stabilizing beta1 integrin and inducing epithelial-mesenchymal transition (EMT) in breast and ovarian cancer. Further, a high RCP expression was significantly correlated with shorter overall survival and disease-free survival of HNSCC patients. However, the molecule mechanisms by which RCP increases HNSCC invasion and metastasis are unclear. In the present study, we demonstrate the role of RCP in oral cancer cell invasiveness and its underlying mechanism.

Methods: Oral cancer YD-10B and YD-38 cells were transiently transfected with RCP constructs. siRNAs were used to analyze the role of specific proteins for Slug and Zeb1 expression. Immunoblotting and immunofluorescence were used to analyze protein expression. Matrigel-coated in vitro insert and wound healing assay were used to analyze cancer cell invasion and migration, respectively.

Results: We observed that ectopic expression of RCP induces invasion of oral cancer cells. Conversely, silencing of RCP expression increased E-cadherin expression and reduced oral cancer cell invasion. In addition, RCP upregulated Zeb1 and Slug expression that is important for RCP-induced oral cancer cell EMT and invasion. Furthermore, we identified that silencing of beta1 integrin efficiently attenuates RCP-induced Zeb1 and Slug expression. In addition, we observed that a selective inhibitor of EGFR kinase activity, Gefitinib, significantly reduces RCP-induced Zeb1 and Slug expression and that RasN17 recovers RCP-induced Zeb1 expression. Finally, RCP increased the viability of oral cancer cells against a chemotherapeutic agent cisplatin.

Conclusion: Collectively, we demonstrate that RCP augments oral cancer cell EMT and invasiveness through a beta1 integrin/EGFR/Ras/Slug and Zeb1 signaling axis, providing potential biomarkers for oral cancer patients therapy.

Citation Format: Jin Young Kim, Kyung Hwa Cho, Bo Young Jeong, Zi Hae Song, Chang Gyo Park, Hoi Young Lee. RCP augments oral cancer cell invasion through Zeb1 and Slug expression [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2019; 2019 Mar 29-Apr 3; Atlanta, GA. Philadelphia (PA): AACR; Cancer Res 2019;79(13 Suppl):Abstract nr 2860.

TGF-β-mediated NADPH oxidase 4-dependent oxidative stress promotes colistin-induced acute kidney injury

Background

Colistin (polymyxin E) is an important constituent of the polymyxin class of cationic polypeptide antibiotics. Intrarenal oxidative stress can contribute to colistin-induced nephrotoxicity. Nicotinamide adenine dinucleotide 3-phosphate oxidases (Noxs) are important sources of reactive oxygen species. Among the various types of Noxs, Nox4 is predominantly expressed in the kidney.

Objectives

We investigated the role of Nox4 and benefit of Nox4 inhibition in colistin-induced acute kidney injury using in vivo and in vitro models.

Methods

Human proximal tubular epithelial (HK-2) cells were treated with colistin with or without NOX4 knockdown, or GKT137831 (most specific Nox1/4 inhibitor). Effects of Nox4 inhibition on colistin-induced acute kidney injury model in Sprague-Dawley rats were examined.

Results

Nox4 expression in HK-2 cells significantly increased following colistin exposure. SB4315432 (transforming growth factor-β1 receptor I inhibitor) significantly inhibited Nox4 expression in HK-2 cells. Knockdown of NOX4 transcription reduced reactive oxygen species production, lowered the levels of pro-inflammatory markers (notably mitogen-activated protein kinases) implicated in colistin-induced nephrotoxicity and attenuated apoptosis by altering Bax and caspase 3/7 activity. Pretreatment with GKT137831 replicated these effects mediated by downregulation of mitogen-activated protein kinase activities. In a rat colistin-induced acute kidney injury model, administration of GKT137831 resulted in attenuated colistin-induced acute kidney injury as indicated by attenuated impairment of glomerulus function, preserved renal structures, reduced expression of 8-hydroxyguanosine and fewer apoptotic cells.

Conclusions

Collectively, these findings identify Nox4 as a key source of reactive oxygen species responsible for kidney injury in colistin-induced nephrotoxicity and highlight a novel potential way to treat drug-related nephrotoxicity.

The YB-1/EZH2/amphiregulin signaling axis mediates LPA-induced breast cancer cell invasion

Lysophosphatidic acid (LPA) has been known to induce epithelial-mesenchymal transition (EMT) to stimulate cancer cell invasion, and resveratrol (3,5,4'-trans-trihydroxystilbene; REV) suppresses the invasion and metastasis of various cancers. The current study aimed to identify the underlying mechanism by which LPA aggravates breast cancer cell invasion and the reversal of this phenomenon. Immunoblotting and quantitative RT-PCR analysis revealed that LPA induces amphiregulin (AREG) expression. Silencing of Y-box binding protein 1 (YB-1) or enhancer of zeste homolog 2 (EZH2) expression efficiently inhibited LPA-induced AREG expression. In addition, transfection of the cells with YB-1 siRNA abrogated LPA-induced EZH2 and AREG expression, leading to attenuation of breast cancer cell invasion. Furthermore, we observed that both REV and 5-fluorouracil (5-Fu) significantly reduce LPA-induced YB-1 phosphorylation and subsequent breast cancer invasion. Importantly, combined treatment of REV with 5-Fu showed more significant inhibition of LPA-induced breast cancer invasion compared to single treatment. Therefore, our data demonstrate that the YB-1/EZH2 signaling axis mediates LPA-induced AREG expression and breast cancer cell invasion and its inhibition by REV and 5-Fu, providing potential therapeutic targets and inhibition of breast cancer.

The Effect of 3-Isocyanato-1-Propene on Adhesive Properties of UV-Curing Urethane/Siloxane Acrylate Resin

We synthesized the urethane/siloxane acrylate oligomer from isophorone diisocyanate (IPDI), hydroxyl alkyl terminated polydimethylsiloxane and 2-hydroxyethyl acrylate (2-HEA). UV-curable resins were formulated from the synthesized oligomer, ethylene glycol phenyl ether acrylate (PHEA), 1,6-hexanediol diacrylate (HDDA), trimethylolpropane triacrylate (TMPTA) as a reactive diluent, 3-isocyanato-1-propene as an adhesion promoter and photoinitiators. The PET film was treated with plasma in order to introduce the functional group on the PET surface and the functional group was observed through X-ray photoelectron spectroscopy (XPS) and the Fourier transform infrared (FT-IR). The adhesion strength between the PET film and the UV-cured resin were increased by using the adhesion promoter. Also, the thermal stability, the modulus and surface hardness were increased, as the adhesion promoter was added.

Resveratrol attenuates norepinephrine-induced ovarian cancer invasiveness through downregulating hTERT expression

Stress hormone norepinephrine (NE) has been associated with acquisition of cancer progression, and naturally occurring phytoalexin resveratrol (REV) has been known to suppress cancer growth and progression. In the present study, we determine the effect of REV on NE-induced ovarian cancer invasiveness. Pretreatment of REV significantly inhibited NE-induced ovarian cancer cell epithelial-to-mesenchymal transition with concomitant recovery of E-cadherin expression. In addition, our data showed that REV downregulates NE-induced human telomerase reverse transcriptase (hTERT) expression through inhibiting Src phosphorylation and HIF-1α expression. Further, REV reduced NE-induced Slug expression and subsequent ovarian cancer invasion. More importantly, combined treatment of REV with a pharmacological inhibitor of beta adrenergic receptor significantly attenuated NE-induced ovarian cancer invasion compared to single treatment. Therefore, we demonstrate interference of a Src and HIF-1α/hTERT/Slug signaling cascade by REV, providing potential therapeutic targets and inhibition of ovarian cancer.

Microdochectomy assisted by ultrasound-guided indigo carmine staining of intraductal lesions: a case report

Spontaneous bloody nipple discharge from a single duct is a significant clinical problem. When performing preoperative marking of the discharging duct, it is sometimes difficult to identify the duct owing to intermittent discharge. Precise preoperative marking of the discharging duct and intraductal lesions is very important to avoid unnecessary wide excision of breast tissue or failure to remove the cause of nipple discharge. We herein present a case of preoperative ultrasound-guided indigo carmine staining in a patient with no discharge on the day of surgery. When a dilated duct is visualized on ultrasound, the targeted duct can be localized using indigo carmine staining, and it is possible to perform a precise minimal volume microdochectomy.

Preferential accumulation of fatty acids in the testis and ovary of cultured and wild sweet smelt Plecoglossus altivelis

The effect of dietary lipid on the fatty acid composition of muscle, testis and ovary of cultured sweet smelt, Plecoglossus altivelis, was investigated and compared with that of wild sweet smelt. Cultured fish were fed three different diets for 12 weeks: a control diet rich in docosahexaenoic acid (DHA, 22:6n-3) and eicosapentaenoic acid (EPA, 20:5n-3) (CO group); a diet deficient in DHA and EPA (DP group); and a diet rich in alpha-linolenic acid (ALA, 18:3n-3), but deficient in DHA and EPA (LP group). The fatty acid composition of muscle and gonad lipids was related with dietary fatty acids. Despite the difference in DHA and EPA content in the diets, muscles and gonads, respectively, contained almost equal levels of DHA and EPA in each CO and DP group. However, the muscle and gonad of the LP group showed a lower level of DHA than other groups, due to having the highest level of ALA. In the wild fish muscle, the DHA content was similar to that of CO and DP groups, but the EPA content showed the highest level in all groups. There was no difference in the muscle fatty acid proportions between male and female. On the other hand, the testes of cultured and wild fish were rich in DHA, EPA, docosapentaenoic acid and arachidonic acid, while ovaries were rich in oleic, palmitoleic, linoleic acids and ALA. Moreover, of all the groups, the fish fatty acid composition of the LP group was closest to that of wild fish. These results indicate that in the sweet smelt, tissue n-3 polyunsaturated fatty acids (PUFAs) greater than C20 can be synthesized from dietary precursors and special fatty acids are preferentially accumulated to the testis or ovary, respectively, to play different physiological functions.

Occupational deaths and injuries in the construction industry

This study concerned with the characteristics of occupational deaths and injuries in the construction industry of South Korea. The national statistics of industrial accidents in the years 1991-1994 were extracted from the annual publications of the Ministry of Labor. These data were analyzed in terms of the size of company, age of injured person, work experience, accident type, injury type, injured part of body, and agency of accident. The results show that there are some patterns in the characteristics of occupational injuries of construction industry: (1) deaths occur more frequently in the older workers; (2) the most common type of accident is 'falls from a height'; (3) 'fracture' is the leading injury type; (4) the body sites most vulnerable to injury are the leg, foot and toe in the non-fatal injuries, while the head, face, and neck in deaths; (5) most of the accidents occurred from the temporary construction or fabric. The results also show that there are differences in accident characteristics between occupational deaths and nonfatal injuries. These findings identified in this study can be used to decide the accident prevention programs.

Hydrocarbon chain distribution of ether phospholipids of the ascidian Halocynthia roretzi and the sea urchin Strongylocentrotus intermedius

The contents and compositions of the 1-O-alk-1'-enyl-2-acyl, 1-O-alkyl-2-acyl, and 1,2-diacyl glycerophospholipids in the muscle and viscera of the ascidian Halocynthia roretzi, and of the gonad of the sea urchin Strongylocentrotus intermedius, which are eaten to some extent in Alaska and in Asia, were analyzed by gas-liquid chromatography. 1-O-Alk-1'-enyl-2-acyl glycerophospholipids were found in all of the samples, accounting for 64.4-69.0% of the ethanolamine glycerophospholipid (EPL). By contrast, the levels of the 1-O-Alk-1'-enyl-2-acyl choline glycerophospholipids (CPL) were low (3.1-5.7%). CPL was rich in the 1-O-alkyl-2-acyl subclass amounting to 12.5-23.9% in the ascidian sample. The level of CPL in the sea urchin gonad was extremely high, amounting to 46.1%. The most prominent alkyl chains in the sn-1 position of CPL from the ascidian muscle were 16:0 (44.6%), 18:1 (26.5%), and 18:0 (10.7%), and of CPL from the sea urchin gonad were 18:0 (36.2%), 16:0 (33.0%), and 18:1 (17.8%). Unusually high levels of odd-numbered alkyl chains, e.g., 19:0 and anteiso 17:0, were detected in the CPL of all samples. The prominent alkenyl chains of EPL were 18:0 (69.4%), 16:0 (10.0%), and 18:1 (8.54%) (not counting the vinyl double bond) for the sea urchin gonad. Relatively high levels of 20:1 alkenyl chains were also present. The glycerol sn-2 positions contained high proportions of polyunsaturated fatty acids. Thus, 20:5n-3 (43.6%) and 22:6n-3 (20.1%) were most abundant in the alkylacyl CPL from the ascidian muscle and 20:5n-3 (54.9%) and 20:4n-6 (30.1%) in alkylacyl CPL from the sea urchin gonad. Despite a possible interconversion of the alkyl and alkenyl chains of each class of the ether phospholipids, they showed few features in common.

Contour representation of sway area in posturography and its application

The representation of postural sway tendency in posturography is important to understand the features of body balance system and a variety of postural disorders. This study is concerned with the contour representation and analysis of postural sway trajectory in posturography. We propose two methodologies to derive the contour of postural sway based on the boundary points of sway area. An algorithm for finding the sway contour in each method was developed, and the experiments were performed to examine the computational efficiency between the methods proposed. Fourteen able-bodied men were asked to stand upright on a force platform to compare the numerical measures of sway shape with other quantitative sway measures used in previous research into balance. The results show that numerical measures of sway contour (area, perimeter, and complexity of sway shape) and radius length diagram can be used to describe the tendency of sway shape, whereas other quantitative sway measures represent the extent of sway amounts.

Respiration effect on standing balance

An attempt was made to determine the effect of respiration on standing balance. Ten able-bodied subjects were asked to stand upright on a force platform and were asked to hold their breath after inspiration and after expiration, and to breathe regularly, 4, 6, and 8 respirations per 20 seconds. Sway was measured over 20-second periods with eyes open and eyes closed. The results show that both respiration and eye condition affect the sway distance of the center of pressure on body balance. The sway distance in holding breath after inspiration is significantly greater than in holding breath after expiration, and increasing the respiration rate produces a greater postural sway. Also, the grade of visual compensation for body balance is higher in the regular respiration condition than in breath holding. These findings are applicable for ergonomics, sports, and clinical situations.