Enhancing circulation to lower limbs during head-down tilt by warming upper body and thighs

BACKGROUND: Long-duration spaceflight results in deconditioning of the cardiovascular system, loss of fluid volume, bone demineralization, and atrophy of skeletal muscles, particularly affecting the lower limbs. We hypothesized that it is possible to improve blood circulation to the lower extremities in simulated microgravity by forcing the blood to deliver heat to the feet through heating parts of the upper body and thighs. METHODS: In Study 1, seven men and four women were assessed in an environmental chamber with head-down tilt (HDT) at 14 degrees, wearing a newly developed shortened multi-compartment liquid cooling/warming garment (SLCWG) with local tubing networks covering parts of the head, torso, thigh, arms, and hands, with fingers, lower leg, and feet exposed. Study 2 was the same as Study 1 with a new cohort of four men and two women, and the assessment of toe blood perfusion on all subjects. Heat was applied as follows: Stage 1--SLCWG inlet water temperature 33 degrees C to stabilize comfort; Stage 2--inlet water temperature 8-10 degrees C (in combination with HDT) to reach a criterion of 25 degrees C finger temperature (Tfing); and Stage 3--inlet water temperature 45 degrees C to restore Tfing to 33 degrees C. RESULTS: Improvement of foot circulation by delivering more heat to the upper body and thighs was noted; increases in toe temperature (Ttoe) suggest enhanced perfusion. From Stage 2 to 3, there were significant increases in Ttoe (p < 0.05), a significant decrease in diastolic BP (DBP) (p < 0.05), and a significant change across stages in subjective perception of foot comfort (p < 0.001) and foot heat (p < 0.06). Further, toe blood perfusion increased significantly from Stage 2 to 3 (p < 0.05). CONCLUSIONS: Moderate partial heating of the upper body/thighs improved blood circulation in the feet in simulated microgravity by delivering heat to the lower extremities through restriction of heat exchange with the environment in the heated body parts. This technique could serve as a supplemental countermeasure for increasing blood circulation to the lower extremities.     

Copy number variation underlies complex phenotypes in domestic dog breeds and other canids

Extreme phenotypic diversity, a history of artificial selection, and socioeconomic value make domestic dog breeds a compelling subject for genomic research. Copy number variation (CNV) is known to account for a significant part of inter-individual genomic diversity in other systems. However, a comprehensive genome-wide study of structural variation as it relates to breed-specific phenotypes is lacking. We have generated whole genome CNV maps for more than 300 canids. Our data set extends the canine structural variation landscape to more than 100 dog breeds, including novel variants that cannot be assessed using microarray technologies. We have taken advantage of this data set to perform the first CNV-based genome-wide association study (GWAS) in canids. We identify 96 loci that display copy number differences across breeds, which are statistically associated with a previously compiled set of breed-specific morphometrics and disease susceptibilities. Among these, we highlight the discovery of a long-range interaction involving a CNV near MED13L and TBX3, which could influence breed standard height. Integration of the CNVs with chromatin interactions, long noncoding RNA expression, and single nucleotide variation highlights a subset of specific loci and genes with potential functional relevance and the prospect to explain trait variation between dog breeds.

Dogs have been the subject of intense study over many decades (Vilà et al. 1999; Ostrander and Wayne 2005; Freedman et al. 2014; Ostrander et al. 2019), providing valuable insight into human history, disease, and evolution (Coelho et al. 2018; Ní Leathlobhair et al. 2018; Wang et al. 2019). Much has been learned about canines through traditional approaches, including genotype studies with microsatellites (Irion 2003), single nucleotide polymorphisms (SNPs) (Gundry et al. 2007; Boyko et al. 2010; Vaysse et al. 2011), and, finally, whole genome sequencing (WGS) (Lindblad-Toh et al. 2005; Freedman et al. 2014; Plassais et al. 2019).As a result of the extensive history of genetic studies in dogs, remarkable advances have been made toward the resolution of the canine phylogeny (vonHoldt et al. 2010; Parker et al. 2017) and the temporal, geographic, and demographic history of dog domestication (Freedman et al. 2014; Shannon et al. 2015; Skoglund et al. 2015). Studies suggest that dogs were initially domesticated from gray wolves 15,000 to 40,000 yr ago (Freedman et al. 2014; Skoglund et al. 2015; Freedman and Wayne 2017; Ostrander et al. 2019), with a rapid diversification of breeds occurring within the past few hundred years. Currently, about 400 dog breeds exist worldwide, 193 recognized by the American Kennel Club and 360 by the Fédération Cynologique Internationale. Breed classification schemes have been proposed based on occupation, morphology, and geographic origin (American Kennel Club 2007; Wucher et al. 2017). The most recent genetic analysis, encompassing nearly 200 breeds and populations, suggests a monophyletic origin for most modern breeds and provides data regarding their origins and timing (Parker et al. 2017). Clusters of genetically similar breeds were identified and assigned to clades, which often reflected occupational and geographical origins.Targeted and genome-wide genotyping approaches have led to the discovery of nearly 400 variants associated with more than 270 traits, over 220 of which correspond to possible models for human diseases (Online Mendelian Inheritance in Animals [OMIA], Sydney School of Veterinary Science, https://omia.org/). Particularly, genome-wide association studies (GWASs) involving modest size cohorts of dogs have led to the identification of variants controlling a variety of morphological, behavioral, and disease traits (Akey et al. 2010; Vaysse et al. 2011; Rimbault et al. 2013; Hayward et al. 2016; MacLean et al. 2019; Plassais et al. 2019).The recent and intense artificial selective pressure exerted on dogs has induced pronounced inter-breed phenotypic differences while preserving intra-breed homogeneity. This process makes dogs of the same breed more likely to share not only morphometric traits but also disease susceptibilities (Karlsson and Lindblad-Toh 2008; Chase et al. 2009; Akey et al. 2010; Boyko et al. 2010; Marchant et al. 2017; Mansour et al. 2018; Ostrander et al. 2019). The level of anatomic similarity among dogs of any one breed is sufficiently strong that genetic studies have been successfully executed using breed standards as phenotypes, thus unraveling the genetic bases of some complex traits such as body size or behavior (Akey et al. 2010; Boyko et al. 2010; Vaysse et al. 2011; Hayward et al. 2016; MacLean et al. 2019; Plassais et al. 2019), which remain elusive, even in humans.However, all these analyses have been performed using a subset of indicative SNPs and, more recently, SNPs from WGSs (Jagannathan et al. 2019; Plassais et al. 2019), but other forms of genomic variation have rarely been studied systematically. In fact, there is still a lack of fine-scale, genome-wide analyses of any variants other than SNPs across dog breeds, a notable exception when compared to humans and other model organisms (Yalcin et al. 2011; Brown et al. 2012; Sudmant et al. 2015). Copy number variation (CNV) has been previously studied in canines to elucidate specific phenotypes (Karyadi et al. 2013; Arendt et al. 2014; Waldo and Diaz 2015; Deane-Coe et al. 2018). However, most studies have focused on the comparison of dogs and wolves using array-based technologies, rather than undertaking a comprehensive and unbiased examination of all CNVs across the genome of distinct breeds (Berglund et al. 2012; Schoenebeck et al. 2012). Most CNV-related studies published to date only aimed to identify segmentally duplicated regions and did not aim to produce quantitative copy-number (CN) genotypes (Quilez et al. 2012; Molin et al. 2014). Knowing the exact number of copies at a locus is crucial for an accurate comparison of closely related organisms, such as distinct dog breeds and wild canids.Here, we present a fine-scale CNV map of over 300 canid samples using WGS to produce the most extensive, high-resolution CNV panel in dogs to date. We examine more than 145 individual breeds, as well as nonbreed dogs, including village dogs, dingoes, captive New Guinea singing dogs, and wild canids such as wolves. We employ this data set to determine the ability of CNVs to recreate a current dog phylogeny. Moreover, we test for breed-phenotype associations using an extensive data set of breed standards as individual phenotypes in the first CNV-based GWAS performed in dogs to date.     

Characterization and Compatibility Studies between Policosanol,a New Hypocholesterolemic Drug,and Tablet Excipients Using Differential Scanning Calorimetry (DSC)

Characterisation of policosanol, a new active principle composed of 8 high molecular weight fatty alcohols, viz. 1-tetracosanol, 1-hexacosanol, 1-heptacosanol, 1-octacosanol, 1-nonacosanol, 1-triacontanol, 1-dotriacontanol, and 1-tetratriacontanol, shows it have a very stable, well defined composition which is reproducible from batch to batch. Compatibility studies by differential scanning calorimetry (DSC) and thermogravimetry (TG) gave very useful physicochemical information and reveal the characteristic transitions, as well as the thermal stability of this drug. DSC facilitated compatibility studies between policosanol and several tablet excipients generally used for the manufacture of this pharmaceutical dosage form. It is seen that the combination of policosanol with each excipient in every one of the ratios used did not produce any changes in the melting point of policosanol or those of the excipients mixed with it. Also, no new peaks were observed in the policosanol/excipient mixtures. It can be concluded from these results that no dissolution of policosanol in the excipients occurs, and also that no physicochemical interactions take place between them.     

The Effect of Obesity Class on the Energetics and Mechanics of Walking

Higher mass-normalized net energy cost of walking (NetC_w/kg) and mechanical pendular recovery are observed in obese compared to lean adults. This study aimed to investigate the effect of different classes of obesity on the energetics and mechanics of walking and to explore the relationships between body mass, NetC_w/kg and gait mechanics by using principal component analysis (PCA). NetC_w/kg and gait mechanics were computed in severely obese (SOG; n = 18, BMI = 40.1 ± 4.4 kg·m⁻²), moderately obese (MOG; n = 17, BMI = 32.2 ± 1.5 kg·m⁻²) and normal-weight (NWG; n = 13, BMI = 22.0 ± 1.5 kg·m⁻²) adults during five walking trials (0.56, 0.83, 1.11, 1.39, 1.67 m·s⁻¹) on an instrumented treadmill. NetC_w/kg was significantly higher in SOG compared to NWG (p = 0.019), with no significant difference between SOG and MOG (p = 0.14), nor between MOG and NWG (p = 0.27). Recovery was significantly higher in SOG than in NWG (p = 0.028), with no significant difference between SOG and MOG (p = 0.13), nor between MOG and NWG (p = 0.35). PCA models explained between 17.0% and 44.2% of the data variance. This study showed that: (1) obesity class influences the gait energetics and mechanics; (2) PCA was able to identify two components, showing that the obesity class is associated with lower walking efficiency and better pendulum-like characteristics.     

Insulin resistance and type 2 diabetes in high-fat-fed mice are linked to high glycotoxin intake

Dietary advanced glycosylation end products (AGEs) have been linked to insulin resistance in db/db(++) mice. To test whether dietary AGEs play a role in the progression of insulin resistance in normal mice fed high-fat diets, normal C57/BL6 mice were randomly assigned to high-fat diets (35% g fat), either high (HAGE-HF group; 995.4 units/mg AGE) or low (by 2.4-fold LAGE-HF group; 329.6 units/mg AGE) in AGE content for 6 months. Age-matched C57/BL6 and db/db(++) mice fed regular diet (5% g fat, 117.4 units/mg AGE) served as controls. After 6 months, 75% of HAGE-HF mice were diabetic and exhibited higher body weight (P < 0.001), fasting glucose (P < 0.001), insulin (P < 0.001), and serum AGEs (P < 0.01) than control mice, while none of the LAGE-HF mice were diabetic despite a similar rise in body weight and plasma lipids. The HAGE-HF group displayed markedly impaired glucose and insulin responses during glucose tolerance tests and euglycemic and hyperglycemic clamps and altered pancreatic islet structure and function compared with those of LAGE-HF mice, in which findings resembled those of control mice. The HAGE-HF group had more visceral fat (by two- and fourfold) and more AGE-modified fat (by two- and fivefold) than LAGE-HF and control mice, respectively. In the HAGE-HF group, plasma 8-isoprostane was higher (P < 0.01) and adiponectin lower (P < 0.001) than control mice, while in the LAGE-HF group, these were more modestly affected (P < 0.05). These results demonstrate that the development of insulin resistance and type 2 diabetes during prolonged high-fat feeding are linked to the excess AGEs/advanced lipoxidation end products inherent in fatty diets.     

Hidden Sources of Phosphorus in the Typical American Diet: Does it Matter in Nephrology?

Elevated serum phosphorus is a major, preventable etiologic factor associated with the increased cardiovascular morbidity and mortality of dialysis patients. An important determinant of serum phosphorus is the dietary intake of this mineral; this makes dietary restriction of phosphorus a cornerstone for the prevention and treatment of hyperphosphatemia. The average daily dietary intake of phosphorus is about 1550 mg for males and 1000 mg for females. In general, foods high in protein are also high in phosphorus. These figures, however, are changing as phosphates are currently being added to a large number of processed foods including meats, cheeses, dressings, beverages, and bakery products. As a result, and depending on the food choices, such additives may increase the phosphorus intake by as a much as 1 g/day. Moreover, nutrient composition tables usually do not include the phosphorus from these additives, resulting in an underestimate of the dietary intake of phosphorus in our patients. Our goal is to convey an understanding of the phosphorus content of the current American diet to better equip nephrologists in their attempt to control hyperphosphatemia.     

Restriction of dietary glycotoxins reduces excessive advanced glycation end products in renal failure patients

Advanced glycation endproduct (AGE) levels are elevated in renal failure patients and may contribute to the excessive cardiovascular disease in this population. Diet-derived AGE are major contributors to the total body AGE pool. It was postulated that a reduction in dietary AGE intake might impact on the high circulating AGE levels in renal failure patients. Twenty-six nondiabetic renal failure patients on maintenance peritoneal dialysis were randomized to either a high or a low AGE diet for 4 wk. Three-day dietary records, fasting blood, 24-h urine, and dialysis fluid collections were obtained at baseline and end of study. AGE levels were determined by ELISA for N(epsilon)-carboxymethyl-lysine (CML) and methylglyoxal-derivatives (MG). Eighteen patients completed the study. Low dietary AGE intake decreased serum CML (34%; P < 0.002), serum MG (35%; P < 0.008), CML-LDL (28%; P < 0.011), CML-apoB (25%; P < 0.028), dialysate CML (39%; P < 0.03), and dialysate MG output (40%; P < 0.04). High dietary AGE intake increased serum CML (29%; P < 0.028), serum MG (26%; P < 0.09), CML-LDL (50%; P < 0.011), CML-apoB (67%; P < 0.028), and dialysate CML output (27%; P < 0.01). Serum AGE correlated with BUN (r = 0.6, P < 0.002 for CML; r = 0.4, P < 0.05 for MG), serum creatinine (r = 0.76, P < 0.05 for CML; r = 0.55, P < 0.004 for MG), total protein (r = 0.4, P < 0.05 for CML; r = 0.4, P < 0.05 for MG), albumin (r = 0.4, P < 0.02 for CML; r = 0.4, P < 0.05 for MG), and phosphorus (r = 0.5, P < 0.006 for CML; r = 0.5, P < 0.01 for MG). It is concluded that dietary glycotoxins contribute significantly to the elevated AGE levels in renal failure patients. Moreover, dietary restriction of AGE is an effective and feasible method to reduce excess toxic AGE and possibly cardiovascular associated mortality.