Changes in abdominal subcutaneous fat water content with rapid weight loss and long-term weight maintenance in abdominally obese men and women

Evaluating Sex-specific Differences in Abdominal Fat Volume and Proton Density Fat Fraction at MRI Using Automated nnU-Net-based Segmentation

Sex-specific abdominal organ volume and proton density fat fraction (PDFF) in people with obesity during a weight loss intervention was assessed with automated multiorgan segmentation of quantitative water-fat MRI. An nnU-Net architecture was employed for automatic segmentation of abdominal organs, including visceral and subcutaneous adipose tissue, liver, and psoas and erector spinae muscle, based on quantitative chemical shift-encoded MRI and using ground truth labels generated from participants of the Lifestyle Intervention (LION) study. Each organ's volume and fat content were examined in 127 participants (73 female and 54 male participants; body mass index, 30-39.9 kg/m2) and in 81 (54 female and 32 male participants) of these participants after an 8-week formula-based low-calorie diet. Dice scores ranging from 0.91 to 0.97 were achieved for the automatic segmentation. PDFF was found to be lower in visceral adipose tissue compared with subcutaneous adipose tissue in both male and female participants. Before intervention, female participants exhibited higher PDFF in subcutaneous adipose tissue (90.6% vs 89.7%; P < .001) and lower PDFF in liver (8.6% vs 13.3%; P < .001) and visceral adipose tissue (76.4% vs 81.3%; P < .001) compared with male participants. This relation persisted after intervention. As a response to caloric restriction, male participants lost significantly more visceral adipose tissue volume (1.76 L vs 0.91 L; P < .001) and showed a higher decrease in subcutaneous adipose tissue PDFF (2.7% vs 1.5%; P < .001) than female participants. Automated body composition analysis on quantitative water-fat MRI data provides new insights for understanding sex-specific metabolic response to caloric restriction and weight loss in people with obesity. Keywords: Obesity, Chemical Shift-encoded MRI, Abdominal Fat Volume, Proton Density Fat Fraction, nnU-Net ClinicalTrials.gov registration no. NCT04023942 Supplemental material is available for this article. Published under a CC BY 4.0 license.

Evaluating Dielectric Properties for Assessing Water Content at Acupuncture Points: New Methodology

Importance

Understanding acupuncture point microenvironments is vital for optimizing treatment efficacy. Evaluating changes in water content at these points can provide further insights into the effects of acupuncture on tissues.

Objective

This study aimed to measure tissue dielectric constant (TDC) and assess changes in water content, specifically at stomach 36 (ST36, Zusanli) and spleen 6 (SP6, Sanyinjiao) acupuncture points.

Methods

In a controlled, blinded, randomized trial, 113 healthy volunteers were divided into six groups based on TDC sensor diameters (XS, M, and L): three control groups and three acupuncture groups. They were assessed at three time points: T1, baseline; T2, 20 min post-needle withdrawal; and T3, 40 min post-needle withdrawal. Electrical impedance (EI) was also analyzed. Significance level was set at p < 0.001.

Results

TDC at ST36 and SP6 significantly decreased with the XS probe at T2 and T3 compared with that at T1 (F8, 452: 54.61). TDC did not significantly vary between T2 and T3 with M and L probes. EI data indicated that the current passage increased in the SP (F2, 226: 39.32) and ST (F2, 226: 37.32) groups during T2 and T3 compared with that during T1 within their respective groups and controls.

Conclusions

and Relevance: This study demonstrated the efficacy of TDC measurements in detecting water content fluctuations at acupuncture points and their responses to needles. TDC measurements, which were validated against EI, provide valuable insights into acupuncture point microenvironments and thus help optimize treatments.

Skin optical properties in the obese and their relation to body mass index: a review

SIGNIFICANCE

Obesity is a worldwide epidemic contributing directly to several cardiovascular risk factors including hypertension and type 2 diabetes. Wearable devices are becoming better at quantifying biomarkers relevant for the management of health and fitness. Unfortunately, both anecdotal evidence and recent studies indicate that some wearables have higher levels of error when utilized by populations with darker skin tones and high body mass index (BMI). There is an urgent need for a better evaluation of the limits of wearable health technologies when used by obese individuals.

AIMS

(1) To review the current know-how on changes due to obesity in the skin epidermis, dermis, and subcutis that could affect the skin optical properties; (2) for the green wavelength range, to evaluate the difference in absorption and scattering coefficients from the abdominal skin between individuals with and without elevated BMI. The changes include alterations in layer thickness and cell size, as well as significant differences in chromophores and scatterer content, e.g., water, hemoglobin, collagen, and lipids.

APPROACH

We have summarized literature pertaining to changes in skin and its components in obesity and report the results of our search using articles published between years 1971 and 2020. A linear model was used to demonstrate the absorption and reduced scattering coefficient of the abdominal skin of individuals with and without elevated BMI in the green wavelength range (530 to 550 nm) that is typically found in most wearables.

RESULTS

The general trends indicate a decrease in absorption for both dermis and subcutis and an increase in reduced scattering for both epidermis and dermis. At 544-nm wavelength, a typical wavelength used for photoplethysmography (PPG), the absorption coefficient's relative percentage difference between high and low BMI skin, was 49% in the subcutis, 19% in the dermis, and negligible in the epidermis, whereas the reduced scattering coefficient relative difference was 21%, 29%, and 165% respectively.

CONCLUSIONS

These findings suggest that there could be significant errors in the output of optical devices used for monitoring health and fitness if changes due to obesity are not accounted for in their design.

Fat unsaturation measures in tibial, subcutaneous and breast adipose tissue using short and long TE MRS at 3 T

Fat unsaturation and poly-unsaturation measures can be obtained in vivo with magnetic resonance spectroscopy (MRS) through the olefinic (≈5.4 ppm) and diallylic (≈2.8 ppm) resonances, respectively. Long echo time (TE) MRS sequences have been previously optimized for olefinic/methylene (≈1.3 ppm) or olefinic/methyl (≈0.9 ppm) measures. The objectives of this work, using a Point RESolved Spectroscopy (PRESS) sequence, are to: 1) Investigate olefinic, methyl and methylene resonance decay in subcutaneous, tibial, and breast adipose tissue to determine if a direct comparison of unsaturation measures can be made without correction for T₂ losses. 2) Assess intra-individual fat unsaturation and poly-unsaturation measures in the three adipose tissues. 3) Estimate correction factors for olefinic to methylene ratios to compensate for J-coupling and T₂ relaxation losses that take place when increasing PRESS TE from 40 ms to 200 ms (previously optimized long-TE). 4) Investigate the utility of an inversion recovery for resolving the olefinic resonance from water in adipose tissue. PRESS spectra were acquired from the three adipose regions (breast in female only) in healthy volunteers at 3 T. It was found that olefinic and methyl signal decays faster in breast tissue compared to in tibial bone marrow. Poly-unsaturation measures (diallylic/methylene) differ for tibial bone marrow compared to subcutaneous and breast adipose tissue, with average values of 1.7 ± 0.4, 2.2 ± 0.4, and 2.3 ± 0.8%, respectively. PRESS (TE = 40 ms) with an inversion recovery resolves the olefinic and water resonances in breast tissue with a signal to noise ratio approximately six times greater than that using PRESS with a TE of 200 ms. Stimulated Echo Acquisition Mode (STEAM) with a TE of 20 ms (mixing time of 20 ms) was also combined with IR to resolve the olefinic resonance from that of water is spinal bone marrow.

Adipose-Derived Stem Cells Improve the Aging Skin of Nude Mice by Promoting Angiogenesis and Reducing Local Tissue Water

BACKGROUND

Adipose-derived stem cells (ASCs) are considered promising cells for skin rejuvenation. However, whether the angiogenetic effect of ASCs plays an important role in the treatment of aging skin and its influence on skin tissue remain elusive.

OBJECTIVES

The aim of this study was to evaluate the effect of ASCs on angiogenesis and local tissue water (LTW) in the aging skin of nude mice.

METHODS

Twelve nude mice were randomly divided into a UVB-induced photoaging group and a natural aging group. After the mouse model had been established, ASCs and phosphate-buffered saline (PBS) were then each injected into different sides of the dorsal skin of the mice. Blood perfusion and LTW content were measured. After 7 weeks, mice were killed, and skin samples were collected to measure the thickness of the dermis, the density of the capillaries, and the expression of angiogenic growth factors.

RESULTS

ASC therapy significantly increased the thickness of the dermis, the number of capillaries, and the expression of some angiogenic growth factors (vascular endothelial growth factor, insulin-like growth factor 1, and epidermal growth factor). At 7 weeks after injection, blood perfusion was significantly higher on the side injected with ASCs than on the side injected with PBS. LTW content was increased in the PBS-injected side, but the ASC-injected side showed no significant changes over time.

CONCLUSIONS

ASCs increased dermal thickness, promoted angiogenesis, and reduced LTW content in the skin of photoaging mice, providing a potential clinical therapy for skin rejuvenation.

Sensor-Based Detection of the Severity of Hyperkeratosis in the Teats of Dairy Cows

The aim of this study was to evaluate whether the severity of hyperkeratosis (HK) in the teats of dairy cows can be assessed by a dielectric measurement. The study focused on surveying the occurrence of hyperkeratosis in a total of 241 teats of lactating dairy cows. A scoring system consisting of four categories was used to macroscopically assess the severity of HK. Additionally, the dielectric constant (DC) of all teats with milkability was measured in a double iteration with the MoistureMeterD (Delfin Technologies, Kuopio, Finland) on four different days. The Spearman rank correlation coefficient revealed a negative correlation between the DC and HK score (rs = −0.55 to −0.36). The results of the regression analysis showed that the DC values differed significantly between healthy teat ends (≤2) and teat ends with HK (≥3). Thus, the non-invasive measurement of DC provides a promising method of objectively assessing the occurrence and severity of HK.

Morphological and Mechanical Properties of the Human Patella Tendon in Adult Males With Achondroplasia

Achondroplasia is a genetic mutation of fibroblast growth factor receptor resulting in impaired growth plate development in long bones due to lower collagen turnover. Despite the characteristic shorter stature and lower strength in Achondroplasic groups, little is known of the tendon mechanical properties under loading. The aim of this study was therefore to conduct a between measure design of patella tendon (PT) mechanical properties (stress, strain, stiffness and Young's Modulus) in 10 men with Achondroplasia (22 ± 3 years) and 17 male controls (22 ± 2 years). PT mechanical properties were measured during isometric maximal voluntary contraction (iMVC) of the knee extensors using ultrasonography. The Achondroplasic group produced 54% less stress at iMVC than controls (29.4 ± 8.0 v 64.5 ± 14.0 MPa, P < 0.001, d = 3.12). Maximal excursion of the Achondroplasic PT was 22% less than controls at iMVC (7.4 ± 2.1 v 5.5 ± 1.7 mm, P < 0.001, d = 0.99), but there was no difference in strain between groups (13 ± 4 v 13 ± 3%, P > 0.05). Achondroplasic PT were 47% less stiff (748 ± 93 v 1418 ± 101 N·mm⁻¹, P < 0.001, d = 6.89) and had a 51% lower Young's modulus (0.39 ± 0.09 v 0.77 ± 0.14 GPa, P < 0.001, d = 3.46) than controls at iMVC. Achondroplasic PT are indeed more compliant than controls which may contribute to lower relative force production. The causes of higher Achondroplasic PT compliance are unclear but are likely due to the collagen related genetic mutation which causes Achondroplasia.

Effects of heat stress and insulin sensitizers on pig adipose tissue

Heat stress (HS) negatively impacts several swine production variables, including carcass fat quality and quantity. Pigs reared in HS have more adipose tissue than energetically predicted, explainable, in part, by HS-induced hyperinsulinemia. Study objectives were to evaluate insulin's role in altering fat characteristics during HS via feeding insulin-sensitizing compounds. Forty crossbred barrows (113 ± 9 kg BW) were randomly assigned to one of five environment by diet treatments: 1) thermoneutral (TN) fed ad libitum (TNAL), 2) TN and pair-fed (TNPF), 3) HS fed ad libitum (HSAL), 4) HS fed ad libitum with sterculic oil (SO) supplementation (HSSO; 13 g/d), and 5) HS fed ad libitum with dietary chromium (Cr) supplementation (HSCr; 0.5 mg/d; Kemin Industries, Des Moines, IA). The study consisted of three experimental periods (P). During P0 (2 d), all pigs were exposed to TN conditions (23 ± 3 °C, 68 ± 10% RH) and fed ad libitum. During P1 (7 d), all pigs received their respective dietary supplements, were maintained in TN conditions, and fed ad libitum. During P2 (21 d), HSAL, HSSO, and HSCr pigs were fed ad libitum and exposed to cyclical HS conditions (28 to 33 °C, 58 ± 10% RH). The TNAL and TNPF pigs remained in TN conditions and were fed ad libitum or pair-fed to their HSAL counterparts. Rectal temperature (TR), respiration rate (RR), and skin temperature (TS) were obtained daily at 0600 and 1800 h. At 1800 h, HS exposed pigs had increased TR, RR, and TS relative to TNAL controls (1.13 °C, 48 bpm, and 3.51 °C, respectively; P < 0.01). During wk 2 and 3 of P2, HSSO pigs had increased 1800 h TR relative to HSAL and HSCr (~0.40 and ~0.42 °C, respectively; P ≤ 0.05). Heat stress decreased ADFI and ADG compared to TNAL pigs (2.24 vs. 3.28 and 0.63 vs. 1.09 kg/d, respectively; P < 0.01) and neither variable was affected by SO or Cr supplementation. Heat stress increased or tended to increase moisture content of abdominal (7.7 vs. 5.9%; P = 0.07) and inner s.c. (11.4 vs. 9.8%; P < 0.05) adipose depots compared to TNAL controls. Interestingly, TNPF pigs also had increased adipose tissue moisture content and this was most pronounced in the outer s.c. depot (15.0 vs. 12.2%; P < 0.01) compared to TNAL pigs. Heat stress had little or no effect on fatty acid composition of abdominal, inner, and outer s.c. adipose tissue depots. In summary, the negative effects of HS on fat quality do not appear to be fatty acid composition related, but may be explained by increased adipose tissue moisture content.

Rapid Weight Loss vs. Slow Weight Loss: Which is More Effective on Body Composition and Metabolic Risk Factors?

BACKGROUND

Achieving weight loss (WL) in a short time regardless of its consequences has always been the focus of many obese and overweight people. In this study, anthropometric and metabolic effects of two diets for rapid and slow WL and their consequences were examined.

METHODS

Forty-two obese and overweight individuals were randomly divided to 2 groups; rapid WL (weight loss of at least 5% in 5 weeks) and slow WL (weight loss of at least 5% in 15 weeks). To compare the effects of the rate of WL in 2 groups, the same amount of was achieved with different durations. Anthropometric indices, lipid, and glycemic profiles, and systolic and diastolic blood pressures were evaluated before and after the intervention.

RESULTS

Both protocols of rapid WL and slow WL caused reduction in waist circumference, hip circumference, total body water, body fat mass, lean body mass, and resting metabolic rate (RMR). Further reduction in waist circumference, hip circumference, fat mass, and percentage of body fat was observed in slow WL and decreased total body water, lean body mass, fat free mass, and RMR was observed in rapid WL. Improvement in lipid and glycemic profiles was observed in both groups. Reduction of low-density lipoprotein and fasting blood sugar, improvement of insulin resistance, and sensitivity were more significant in rapid WL in comparison to slow WL.

CONCLUSIONS

Weight Loss regardless of its severity could improve anthropometric indicators, although body composition is more favorable following a slow WL. Both diets improved lipid and glycemic profiles. In this context, rapid WL was more effective. (IRCT2016010424699N2).

Diffuse optical spectroscopic imaging of subcutaneous adipose tissue metabolic changes during weight loss

Background

Changes in subcutaneous adipose tissue (AT) structure and metabolism have been shown to correlate with the development of obesity and related metabolic disorders. Measurements of AT physiology could provide new insight into metabolic disease progression and response to therapy. An emerging functional imaging technology, Diffuse Optical Spectroscopic Imaging (DOSI), was used to obtain quantitative measures of near infrared (NIR) AT optical and physiological properties.

Methods

10 overweight or obese adults were assessed during three-months on calorie-restricted diets. DOSI-derived tissue concentrations of hemoglobin, water, and lipid and the wavelength-dependent scattering amplitude (A) and slope (b) obtained from 30 abdominal locations and three time points (T0, T6, T12) were calculated and analyzed using linear mixed effects models, and were also used to form 3D surface images.

Results

Subjects lost a mean of 11.7 ± 3.4% of starting weight, while significant changes in A (+0.23 ± 0.04 mm⁻¹, adj. p < 0.001), b (−0.17 ± 0.04, adj. p < 0.001), tissue water fraction (+7.2 ± 1.1%, adj. p < 0.001) and deoxyhemoglobin [HbR] (1.1 ± 0.3 µM, adj. p < 0.001) were observed using mixed effect model analysis.

Discussion

Optical scattering signals reveal alterations in tissue structure which possibly correlate with reductions in adipose cell volume, while water and hemoglobin dynamics suggest improved AT perfusion and oxygen extraction. These results suggest that DOSI measurements of NIR optical and physiological properties could be used to enhance understanding of the role of AT in metabolic disorders and provide new strategies for diagnostic monitoring of obesity and weight loss.

Age-related changes in male forearm skin-to-fat tissue dielectric constant at 300 MHz

Prior research suggests that tissue dielectric constant (TDC) values are useful to assess localized skin water in females for early diagnosing breast cancer treatment-related lymphoedema and TDC values in young adults have shown gender differences. However, no TDC data are available for older males nor have ageing effects been studied despite known shifts in water state and other skin age-related changes. Thus our goals were to (i) characterize TDC values at various skin depths in young and older males, (ii) determine the dependence of these values on body composition parameters and (iii) establish inter-arm TDC ratios for use as normal male reference values. TDC measurements were made to depths of 0·5, 1·5, 2·5 and 5·0 mm bilaterally on volar forearm skin in 60 males in three groups of 20 that had mean ages ± SD of 24·0 ± 0·9, 40·0 ± 12·9 and 71·0 ± 8·0 years. Total body fat and water percentages were determined via bioimpedance at 50 KHz. Results showed that (i) for all age groups TDC values decreased with increasing depth, (ii) TDC values were not statistically different among age groups except at a depth of 0·5 mm, (iii) TDC values were highly negatively correlated with total body fat and (iv) inter-arm ratios varied little among age groups and depths. It is concluded that (i) age-related larger TDC values at only the shallowest depth is consistent with skin water shifting state from bound to more mobile in the oldest group and (ii) inter-arm ratios at any depth provide a basis to test for unilateral oedema.

High consumption of fructose rather than glucose promotes a diet-induced obese phenotype in Drosophila melanogaster

During the last 20 years, there has been a considerable scientific debate about the possible mechanisms of induction of metabolic disorders by reducing monosaccharides such as glucose or fructose. In this study, we report the metabolic rearrangement in response to consumption of these monosaccharides at concentrations ranging from 0.25% to 20% in a Drosophila model. Flies raised on high-glucose diet displayed delay in pupation and increased developmental mortality compared with fructose consumers. Both monosaccharides at high concentrations promoted an obese-like phenotype indicated by increased fly body mass, levels of uric acid, and circulating and stored carbohydrates and lipids; and decreased percentage of water in the body. However, flies raised on fructose showed lower levels of circulating glucose and higher concentrations of stored carbohydrates, lipids, and uric acid. The preferential induction of obesity caused by fructose in Drosophila was associated with increased food consumption and reduced mRNA levels of DILP2 and DILP5 in the brain of adult flies. Our data show that glucose and fructose differently affect carbohydrate and lipid metabolism in Drosophila in part by modulation of insulin/insulin-like growth factor signaling. Some reported similarities with effects observed in mammals make Drosophila as a useful model to study carbohydrate influence on metabolism and development of metabolic disorders.

Effect of weight and body composition changes on waist measurement of severely obese women receiving carbohydrate-restricted diet

OBJECTIVE: To evaluate the effect of weight and body composition changes on waist measurement of severely obese women receiving a low-carbohydrate diet for a short-term. METHODS: Nineteen severely obese women divided into an intervention and a control group received a low-carbohydrate diet and a conventional diet, respectively, both with 1,200kcal, for seven days. Anthropometric measurements such as weight, body mass index, arm circumference, waist circumference (at the navel), two proposed measurements of waist circumference (waist circumference 1, 10cm above the navel; and waist circumference 2, 20cm above the navel), hip circumference; and body composition (lean mass and fat mass) were performed at baseline and end of the study. RESULTS: There was significant reduction of all variables in the intervention group (p<0.01), but the control group had no change in waist circumference (p=0.06) and hip circumference (p=0.36). Patients of the intervention group presented greater weight loss (4.4kg, p<0.01) and reduction of body mass index, waist circumference, waist circumference 1, waist circumference 2 (p<0.01), and fat mass (p=0.04) than the control group. CONCLUSION: The weight loss and body composition changes were greater in the low-carbohydrate group than in the conventional-diet group, and they had a greater impact on waist measurements. The proposed measurements (waist circumference 1 and waist circumference 2) were sensitive to weight reduction in both groups.

Very-low-energy diets and morbidity: a systematic review of longer-term evidence

Evidence from the literature supports the safe use of very-low-energy diets (VLED) for up to 3 months in supervised conditions for patients who fail to meet a target weight loss using a standard low-fat, reduced-energy approach. There is, however, a need for longer-term outcomes on obesity and associated morbidities following a VLED. The present systematic review aims to investigate longer-term outcomes from studies using VLED, with a minimum duration of 12 months, published between January 2000 and December 2010. Studies conducted in both children and adults, with a mean/median BMI of ≥ 28 kg/m2 were included. PubMed, MEDLINE, Web of Science and Science Direct were searched. Reference lists of studies and reviews were manually searched. Weight loss or prevention of weight gain and morbidities were the main outcomes assessed. A total of thirty-two out of 894 articles met the inclusion criteria. The duration of the studies ranged from 12 months to 5 years. Periods of VLED ranged from 25 d to 9 months. Several studies incorporated aspects of behaviour therapy, exercise, low-fat diets, low-carbohydrate diets or medication. Current evidence demonstrates significant weight loss and improvements in blood pressure, waist circumference and lipid profile in the longer term following a VLED. Interpretation of the results, however, was restricted and conclusions with which to guide best practice are limited due to heterogeneity between the studies. The present review clearly identifies the need for more evidence and standardised studies to assess the longer-term benefits from weight loss achieved using VLED.

Weight loss and its relation to fat aspiration yields in liposuction: a survey in 48 patients

BACKGROUND

Liposuction surgeons often observe individually fluctuating amounts of aspirated fat. In patients with sagging skin due to previous weight loss there is a tendency of decreased fat aspiration volumes.

OBJECTIVE

To study the influence of weight loss on fat aspiration volumes in a series of 48 patients.

METHODS

We matched individuals of the same gender, but with a different weight history from a vast number of patients who had undergone liposuction surgery. The aspirated fat to wetting solution ratio (FWR) of the circumferential abdominal region was evaluated in three groups: A - patients with no weight loss (n = 16; 8 males/ 8 females), B - patients with a history of moderate weight loss (weight loss 5-10% of body weight; n = 16; 8 males/8 females), and C - patients who had a massive weight loss prior to surgery (weight loss exceeding 15% of body weight; n = 16; 8 males/8 females).

RESULTS

The aspirated FWR was 3.4 ± 0.5, 1.0 ± 0.3 and 0.4 ± 0.2 in groups A, B and C, respectively. The differences between the groups were statistically significant (p < 0.001).

CONCLUSION

There are significant differences in patients with moderate or massive weight loss in regard to fat aspiration volumes compared to patients without prior weight loss. These findings point to the importance of a weight loss history prior to surgery. Regardless of lower fat aspiration yields in patients with massive weight loss, good results are still achievable. This is not only due to volume reduction but to skin tightening.

Update on adipose tissue blood flow regulation

According to Fick's principle, any metabolic or hormonal exchange through a given tissue depends on the product of the blood flow to that tissue and the arteriovenous difference. The proper function of adipose tissue relies on adequate adipose tissue blood flow (ATBF), which determines the influx and efflux of metabolites as well as regulatory endocrine signals. Adequate functioning of adipose tissue in intermediary metabolism requires finely tuned perfusion. Because metabolic and vascular processes are so tightly interconnected, any disruption in one will necessarily impact the other. Although altered ATBF is one consequence of expanding fat tissue, it may also aggravate the negative impacts of obesity on the body's metabolic milieu. This review attempts to summarize the current state of knowledge on adipose tissue vascular bed behavior under physiological conditions and the various factors that contribute to its regulation as well as the possible participation of altered ATBF in the pathophysiology of metabolic syndrome.

Failure to increase postprandial blood flow in subcutaneous adipose tissue is associated with tissue resistance to adrenergic stimulation

AIMS

Adequate adipose tissue blood flow (ATBF) is essential for its metabolic and endocrine functions. From a metabolic point of view, sufficient increases in ATBF after meals permits full storage of excess energy into fat, thus protecting other tissues against the toxic effects of fatty acids and glucose spillover. It was previously shown that postprandial increases in ATBF are blunted in obese and insulin-resistant subjects, and that much of the postprandial ATBF response is the result of β-adrenergic activation. Examination of previously recorded data on postprandial ATBF responses revealed an underlying heterogeneity, with postprandial ATBF being largely unresponsive to food stimuli in a substantial proportion of normal weight healthy people (low responders). Our study tests the hypothesis that this unresponsive pattern is due to resistance to β-adrenergic stimulation in adipose tissue.

METHODS

Five responders and five low responders were selected from a previously studied cohort and matched for BMI (20.5±0.7 vs 22±1 kg/m(2), respectively), gender (male/female: 2/3) and age (30±3 vs 37±6 years). Subcutaneous adipose tissue microinfusions of stepwise increasing doses of isoproterenol were performed with concomitant monitoring of blood flow, using the (133)Xenon washout technique.

RESULTS

Although BMI was similar between responders and low responders, there were significant differences in fat mass (9.9±1.6 vs 14.4±1.6 kg; P<0.05) and four-point skinfold thickness (33±4 vs 52±16 mm; P<0.05). Lack of ATBF response to oral glucose was confirmed in the low responder group. In responders, ATBF was higher at baseline (5.4±1 vs 3.4±1 mL/min/100 g of tissue) and responded more distinctly to increasing isoproterenol doses (10(-8) M: 7.6±1.4 vs 4.9±1; 10(-6) M: 12.5±1.7 vs 7.5±1.6; and 10(-4) M: 20 ±1.7 vs 9±0.9 mL/min/100 g of tissue).

CONCLUSION

These data suggest that the lack of glucose-stimulated ATBF is associated with resistance to sympathetic activation in adipose tissue.

Subcutaneous adipose tissue metabolism and pharmacology: a new investigative technique

According to the Fick principle, any metabolic or hormonal exchange through a given tissue depends on the product of blood flow by arteriovenous difference. Because adipose tissue plays dual storage and endocrine roles, regulation of adipose tissue blood flow (ATBF) is of pivotal importance. Monitoring ATBF in humans can be achieved through different methodologies, such as the 133Xe washout technique, considered to be the “gold standard”, as well as microdialysis and other methods that are not well validated as of yet. This report describes a new method, called “adipose tissue microinfusion” or “ATM”, which simultaneously quantifies ATBF by combining the 133Xe washout technique together with variations of ATBF induced by local infusion of vasoactive agents. The most appropriate site for ATM investigation is the subcutaneous adipose tissue of the anterior abdominal wall. This innovative method conveniently enables the direct comparison of the effects on ATBF of any vasoactive compound, drug, or hormone against a contralateral saline control. The ATM method improves the accuracy and feasibility of physiological and pharmacological studies on the regulation of ATBF in vivo in humans.

A randomized controlled trial of therapeutic lifestyle modification in rural women with metabolic syndrome: a pilot study

The aim of the study was to identify the effects of the therapeutic lifestyle modification (TLM) program on women with the metabolic syndrome in rural areas. Thirty-two women with the metabolic syndrome were randomly assigned to the intervention or control group. The women in the intervention group participated in a 4-week TLM program consisting of health screening, education, exercise, diet, and counseling. Those in the control group received a booklet with basic education for metabolic syndrome. Repeated-measures analysis of variance was used for analyzing the effects of the TLM intervention on anthropometric indicators, serologic assays, and psychosocial outcomes. The participants in the intervention group showed significant reductions in body weight (-4.6 kg vs -2.0 kg), waist circumference (-6.2 cm vs -1.7 cm), and triglyceride levels (-52.2 mg/dL vs -2.2 mg/dL) compared with those in the control group at 4 weeks (P < .01). In addition, the TLM intervention group showed significant positive behavior changes; almost all of the women tried to control their intake of food and their weight and to exercise 3 times per week. The TLM intervention showed no group and time interaction effect on systolic blood pressure, fasting glucose, high-density lipoprotein cholesterol, or low-density lipoprotein cholesterol levels. However, there was a positive time effect; after the program, high-density lipoprotein cholesterol levels increased and systolic blood pressure, fasting glucose, and low-density lipoprotein cholesterol decreased compared with levels before the intervention in both groups. These results indicate that a well-developed comprehensive TLM intervention can improve metabolic syndrome over a short-term period.

Measurement of oedema in irritant-exposed skin by a dielectric technique

BACKGROUND

Easily applicable water-specific instruments measuring local oedema in skin are not available. The aim of this study is to demonstrate quantitative assessment of skin oedema with the dielectric technique by measuring increase of skin water content related to sodium lauryl sulphate (SLS)-induced irritant contact dermatitis.

METHODS

Irritant skin reaction and resulting oedema were induced by an irritant patch test on volar forearms in 12 healthy volunteers with the application of 1% SLS for 6 h. After occlusion the volunteers were divided into two groups: the patch test site of group I (six volunteers) received no treatment other than a base cream for the skin reaction, while for group II (six volunteers) a strong corticosteroid (clobetasol propionate) was applied on the irritant skin. During a follow-up of 72 h, erythema was scored visually, and irritant-induced oedema was measured with a novel water-specific instrument MoistureMeter-D.

RESULTS

In the untreated irritant skin, a maximum increase of 45% in skin water content was found at 10 h postocclusion and water content was still elevated at 72 h. With these persons, the degree of oedema agreed well with the ultrasound-measured skin thickness (P=0.053). In the corticosteroid-treated skin, an increase of 8% in water content was measured during 72 h but there was no correlation between oedema and skin thickness. There was no correlation between erythema and oedema in untreated or corticosteroid-treated skin.

CONCLUSION

The new instrument can easily be applied for noninvasive quantitative evaluation of local oedema and fluid retention in irritant-exposed skin.

Validation of a new dielectric device to assess changes of tissue water in skin and subcutaneous fat

Easily applicable and inexpensive water-specific techniques to evaluate local oedema, swollen tissue problems and fluid retention in humans are not available. In the present investigation a recently constructed non-invasive device for a local measurement of changes in tissue water in human skin and subcutaneous fat (SSF) was validated. The instrument transmits an ultra high-frequency electromagnetic (EM) wave of 300 MHz into a coaxial line and further into an open-ended coaxial probe which is in contact with the skin. Due to the dimensions of the applied probe the penetration of the EM field extends to subcutaneous fat. A major part of the EM energy is absorbed by tissue water while the rest is reflected back into a coaxial line. From the information of the reflected wave an electrical parameter, directly proportional to tissue water content, called a dielectric constant of SSF, was calculated. For system validation, the decrease of water content in SSF measured with the dielectric technique in the volar forearm of seven patients during haemodialysis treatment was compared with the decrease of the circumference of the forearm and the amount of fluid removed. Statistically highly significant correlations were obtained between the decreasing dielectric constant (i.e. water content) of the SSF and the fluid removed during haemodialysis treatment (r = -0.99, p < 0.01) and between the decreasing dielectric constant and the circumference of the arm (r = 0.97, p < 0.05). The sensitivity of the dielectric method was four-fold compared with the circumferential measurement. The repeatability 3.0% was not dependent on the phase of haemodialysis. The new device allows an easy and non-invasive measurement technique to assess changes of tissue water in SSF.