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Biosensors and chemical sensors for healthcare applications are garnering interest due to their potential to provide continuous and real‐time physiological information, chemical information, and noninvasive measurements of biochemical markers in human biofluids, such as tears, saliva, sweat, interstitial fluid, and human volatiles. Recent developments have focused on electrochemical biosensors and monitoring of metabolites, proteins, chemicals, and bacteria. The measurement of biophysical quantities of the human body has been studied in healthcare and medicine. Many flexible, wearable, and detachable sensors have been developed and commercialized to monitor relevant parameters in sports, healthcare, and medicine. Here, we introduce many challenges regarding the integration of sensors and biosensors into the monitoring of biological and chemical information for the internet of things (IoT) in healthcare. IoT sensors are set to improve quality of life (QoL) and living standards. © 2022 Institute of Electrical Engineers of Japan. Published by Wiley Periodicals LLC. [ABSTRACT FROM AUTHOR]

The low bath bicarbonate concentration ([ HCO3- ]) used by a nephrology group in Japan (25.5 mEq/L), coupled with a bath [acetate] of 8 mEq/L, provided an opportunity to study the acid-base events occurring during hemodialysis when HCO3- flux is from the patient to the bath. We used an analytic tool that allows calculation of HCO3- delivery during hemodialysis and the physiological response to it in 17 Japanese outpatients with an average pre-dialysis blood [ HCO3- ] of 25 mEq/L. Our analysis demonstrates that HCO3- addition is markedly reduced and that all of it comes from acetate metabolism. The HCO3- added to the extracellular fluid during treatment (19.5 mEq) was completely consumed by H+ mobilization from body buffers. In contrast to patients dialyzing with higher bath [ HCO3- ] values in the US and Europe, organic acid production was suppressed rather than stimulated. Dietary analysis indicates that these patients are in acid balance due to the alkaline nature of their diet. In a larger group of patients using the same bath solution, pre-dialysis blood [ HCO3- ] was lower, 22.2 mEq/L, but still in an acceptable range. Our studies indicate that a low bath [ HCO3- ] is well tolerated and can prevent stimulation of organic acid production. [ABSTRACT FROM AUTHOR]

Background: Dilated perivascular spaces in the centrum semiovale (CSO-PVS) are closely related to small vessel disease. However, recent studies have revealed that cerebral amyloid angiopathy can cause dilation of the CSO-PVS and obstruction of interstitial fluid flow along the intramural periarterial drainage.Objective: To examine the severity and age-related prevalence of CSO-PVS through magnetic resonance imaging (MRI) and investigate their clinically relevant factors.Methods: This study included 1,060 subjects who participated in our brain program. The subjects ranged from 23 to 83 years in age and were active in society. The frequencies of the MRI abnormalities of small vessel diseases, including CSO-PVS, were examined. The CSO-PVS severity was classified into three grades: G0, G1, G2, according to the visual rating. The subjects were divided into five age groups and their age-related frequencies were also studied. Using the clinico-laboratory data of 712 subjects, the clinically relevant factors of CSO-PVS were investigated using logistic regression analysis.Results: The frequencies of all G0 ("normal") MRI abnormalities significantly decreased with age. A high prevalence of G2 CSO-PVS was observed (24%) in the youngest group aged≤39 years, whereas other MRI abnormalities in this group were not or rarely observed. In multivariable logistic regression analyses, G2 CSO-PVS was found to be closely associated with age, hypertension, and the estimated glomerular filtration ratio.Conclusions: This study reveals that CSO-PVS begin to develop in subjects aged less than 39 years. Age-related changes are involved. Further studies are necessary to elucidate the pathophysiological role of the CSO-PVS. [ABSTRACT FROM AUTHOR]

• The ECW/TBW ratio was higher in participants with LS risk, frailty, and sarcopenia. • High ECW/TBW ratio strongly reflected late frailty stage and early LS risk stage. • The ECW/TBW ratio is an important indicator in bioelectric impedance analysis. • An increase in the ECW/TBW ratio may reflect locomotive syndrome risk and frailty. Among body composition parameters measured by bioelectrical impedance analysis, the extracellular water-to-total body water (ECW/TBW) ratio is a known prognostic or related factor for various diseases. While concepts such as locomotive syndrome risk, frailty, and sarcopenia are gaining popularity in Japan, their relationship with the ECW/TBW ratio has not been examined in detail. This study aimed to investigate the relationships between them. Of 1081 individuals who underwent health checkups, 550 were included in this study. The evaluations included a two-step test, stand-up test, and a 25-question geriatric locomotive function scale questionnaire. Frailty was diagnosed based on the Japanese version of the Cardiovascular Health Study criteria. Sarcopenia was evaluated according to the Asian Working Group for Sarcopenia criteria. The aforementioned ratio was measured using bioelectrical impedance analysis. The ECW/TBW ratio significantly increased with locomotive syndrome risk, frailty, and sarcopenia (p < 0.001 each). Nevertheless, no significant difference was found between robust and pre-frailty groups (p = 0.71) and normal and pre-sarcopenia groups (p = 0.93). Furthermore, after correcting for age, sex, and body mass index, multiple regression analysis revealed that locomotive syndrome risk (p < 0.001) and frailty (p = 0.001) were significantly associated with an increase in the ECW/TBW ratio, whereas sarcopenia was not (p = 0.97). An increase in the ECW/TBW ratio may reflect locomotive syndrome risk and frailty, but not sarcopenia. In bioelectric impedance analysis, this ratio is an important indicator; if it is high, it is necessary to consider locomotive syndrome risk and frailty. [ABSTRACT FROM AUTHOR]

Flash glucose monitoring (FGM) provides continuous and accessible measurement of the interstitial fluid glucose (ISFG) level and this system is useful for understanding blood glucose fluctuations. We examined differences in postprandial ISFG after the main mealtimes (breakfast, lunch, and dinner) in healthy young Japanese females. Nine healthy young females (aged 21.5±0.6 y old) were enrolled in this study. ISFG was continuously measured by FGM. Participants ate the same meal three times a day consecutively, thereby satisfying their daily energy requirements. Postprandial ISFG fluctuations were evaluated for 4 h after each meal. There were no significant differences in ISFG before the 3 main meals. The postprandial ISFG peak was the lowest after breakfast, increasing in the order of lunch and then dinner. The area under the curve of the 4-h postprandial ISFG was higher after lunch and dinner than after breakfast. The results of this study suggest that postprandial ISFG differ depending on mealtimes in young Japanese females.

The fluid volume balance between intracellular water (ICW) and extracellular water (ECW) gradually changes with age and various medical conditions. Comprehension of these physiological changes would aid in clinical decision-making related to body fluid assessments. A total of 1,992 individuals (753 men and 1,239 women) aged ≥15 yr included in this study had their body composition measurements performed at training gyms in 2014. We developed a regression formula to assess the association of age with the ratio of ECW to ICW in these subjects. The mean ages of male and female subjects were 51.2 ± 15.2 and 57.4 ± 15.2 yr, and their mean body mass indexes were 23.4 ± 3.3 and 21.1 ± 2.8 kg/m 2 , respectively. The total fluid volumes of male and female subjects were 39.6 ± 4.9 and 27.7 ± 3.0 liters, whereas the percent body fat mass per kilogram of body weight were 19 and 26%, respectively. The ECW-to-ICW ratio increased with age because of the steeper decrease in the ICW content than in the ECW content, especially after the age of 70 yr. The regression formulas used for calculating the age-adjusted ECW/ICW ratio were as follows: 0.5857 + 7.4334 × 10 -6  × (age) 2 in men and 0.6062 + 5.5775 × 10 -6  × (age) 2 in women. In conclusion, the fluid imbalance between ICW and ECW contents is driven by decreased cell volume associated with aging and muscle attenuation. Therefore, our proposed formula may serve as a useful assessment tool for the calculation of body fluid composition.

Polydipsia and water intoxication have been found to be care problems in people with schizophrenia in many countries. This Japanese study measured the body fluid distribution and body fat of 80 males with long standing schizophrenia and compared this to that of 64 healthy males, using bioelectrical impedance spectrum analysis (BIS). Participants with schizophrenia exhibited significantly lower percentages of intracellular fluid and total body fluid, and significantly higher percentages of fat. Moreover, the percentage of extracellular fluid was distributed over a wider range. When the percentage body fluid was compared between the two groups by matching body mass index and body fat, intracellular fluid was significantly lower for those participants with schizophrenia. There findings suggest that nurses and other health professionals need to be very cautious when attempting to modify the excessive drinking of fluids by patients with schizophrenia. In mistakenly trying to prevent water intoxication, they may in fact be contributing to dehydration.