High Molecular Weight Group Research Articles

Phthalate and phthalate replacement concentrations in relationship to adiposity in a multi-racial cohort of children

Background/ObjectivePhthalates and phthalate replacements are used in multiple everyday products, making many of them bioavailable to children. Experimental studies suggest that phthalates and their replacements may be obesogenic, however, epidemiologic studies remain inconsistent. Therefore, our objective was to examine the association between phthalates, phthalate replacements and childhood adiposity/obesity markers in children.Subjects/MethodsA cross-sectional study was conducted in 630 racial/ethnically diverse children ages 4–8 years. Urinary oxidative metabolites of DINCH and DEHTP, three low molecular weight (LMW) phthalates, and eleven high molecular weight (HMW) phthalates were measured. Weight, height, waist circumference and % body fat were measured. Composite molar sum groups (nmol/ml) were natural log-transformed. Linear regression models adjusted for urine specific gravity, sex, age, race-ethnicity, birthweight, breastfeeding, reported activity level, mother’s education and pre-pregnancy BMI.ResultsAll children had LMW and HMW phthalate metabolites and 88% had DINCH levels above the limit of detection. One unit higher in the log of DINCH was associated with 0.106 units lower BMI z-score [β = −0.106 (95% CI: −0.181, −0.031)], 0.119 units lower waist circumference z-score [β = −0.119 (95% CI: −0.189, −0.050)], and 0.012 units lower percent body fat [β = −0.012 (95% CI: −0.019, −0.005)]. LMW and HMW group values were not associated with adiposity/obesity.ConclusionsWe report an inverse association between child urinary DINCH levels, a non-phthalate plasticizer that has replaced DEHP in several applications, and BMI z-score, waist circumference z-score and % body fat in children. Few prior studies of phthalates and their replacements in children have been conducted in diverse populations. Moreover, DINCH has not received a great deal of attention or regulation, but it is a common exposure. In summary, understanding the ubiquitous nature of these chemical exposures and ultimately their sources will contribute to our understanding of their relationship with obesity.

Characteristics and efficacy of fish-derived gelatin microparticles as an embolic agent in a rabbit renal model: regulation of the degradation period by molecular weight.

To evaluate the embolic effect of fish-derived gelatin microparticles (GMPs) and compare the degradation periods and biocompatibilities of different molecular weight (MW) GMPs in a rabbit model. GMPs were designed to degrade within 21 days (high MW GMP, 15-30 kDa) and 2 days (low MW GMP, 5-15 kDa) in vivo. Renal arteries of 24 rabbits were embolized using both high and low MW GMPs (155-350 µm). Rabbits were sacrificed either immediately after embolization, or after follow-up (F/U) angiogram on days 2 and 21 of embolization, respectively (4 rabbits in each of the 6 subgroups). Pathological changes of recanalized vessels were evaluated using the Banff classification. For the in vitro study, each type of GMP was mixed with normal saline and morphological changes were compared for 14 days. Fish-derived GMPs showed effective embolization. On 2-day F/U angiography, occluded vessels were more recanalized to the peripheral branches in low MW group. On day 21, a parenchymal perfusion defect recovered to a greater extent in low MW group than that in high MW group. Mean Banff scores for intimal arteritis on 2-day F/U and interstitial fibrosis on 21-day F/U were higher in high MW group (1.75 ± 0.58 vs. 0.19 ± 0.4 and 2.56 ± 0.63 vs. 0.88 ± 0.89; P < .001). On in vitro assessment, low MW GMP lost the spherical shape and degraded, and was invisible on microscopy on day 6, whereas high MW GMP was only partially degraded after 2 weeks. Fish-derived GMPs showed effective embolization in a rabbit model. Low MW GMPs degraded within 2 days with a low inflammatory response.

Low and high molecular weight metabolite concentrations in relationship to adiposity in a multi-site, multi-racial cohort of children

BACKGROUND AND AIM: Low molecular weight (LMW) and high molecular weight (HMW) phthalates are used in multiple everyday products, many of which are bioavailable to children. Evidence concerning the effects of these phthalates on child adiposity remain inconsistent. METHODS: Analyses included 540 racial/ethnically diverse children ages 4-8 in the Environmental Influences on Child Health Outcomes (ECHO) study, a follow-up of the NICHD Fetal Growth Studies. Urinary oxidative metabolites of three LMW and eleven HMW phthalates were determined using liquid chromatography tandem-mass spectrometry. Values were divided by molecular weight and summed to obtain composite LMW and HMW group values (nmol/ml) and natural log transformed. Outcomes were child’s body mass index (BMI) z-score, waist circumference z-score, and percent body fat. Linear regression models were adjusted for urine specific gravity, gender, age, race/ethnicity, birth weight, prolonged exclusive breastfeeding, physical activity, fast-food consumption, smoke exposure, neighborhood traffic, mother’s education and pre-pregnancy BMI. RESULTS:All children had LMW and HMW phthalate group levels at or above the limit of detection. LMW levels were not associated with BMI z-score (β [95% CI]: 0.010 [-0.037. 0.057]), waist circumference z-score (β [95% CI]: -0.002 [-0.046, 0.042]) or percent body fat (β [95% CI]: -0.009 [-0.025, -0.007]). There was evidence of a possible interaction with race (p=0.09), with increased LMW levels in Black children being positively associated with percent body fat (β [95% CI]: 0.005 [0.001, 0.010]). HMW levels were not associated with BMI z-score (β [95% CI]: -0.003 [-0.084, 0.078]), waist circumference z-score (β [95% CI]: 0.021 [-0.055, 0.097]) or percent body fat (β [95% CI]: 0.0003 [-0.008, 0.008]). CONCLUSIONS:In this largely null cross-sectional analysis only LMW phthalates in Black children were associated with percent body fat. Additional research is needed to identify possible interactions between LMW phthalates, HMW phthalates and joint exposure to related chemicals. KEYWORDS: Phthalates, Obesity and metabolic disorders, Children's environmental health

Molecular Weight of Hyaluronic Acid Has Major Influence on Its Efficacy and Safety for Viscosupplementation in Hip Osteoarthritis: A Systematic Review and Meta-Analysis.

This study aimed to compare the efficacy and safety of intra-articular hyaluronic acid (HA) injection with different molecular weights (MWs) for treating hip osteoarthritis (OA). A systematic literature search for relevant studies was conducted in 3 electronic databases, including PubMed, BMJ Journals, and Cochrane Library, from inception to April 2020. Extracted outcomes included visual analogue scale (VAS) (1, 3, and 6 months), Lequesne index (3 and 6 months), and adverse effects. HAs were classified into low-molecular-weight (LMW), moderate-molecular-weight (MMW), high-molecular-weight (HMW), and ultra-high-molecular-weight (UHMW) groups. Meta-analysis was performed using Review Manager 5.3. A total of 15 studies with 614 patients were included. Our meta-analysis showed that the HMW HA group had the best improvement in VAS and Lequesne index compared with other HA groups for all the follow-up visits. Moreover, the HMW group demonstrated significantly better improvement than the other groups in VAS at 6-month follow-up and in Lequesne index at 3- and 6-month follow-ups. Analysis for adverse effects revealed low rates of systemic adverse effects (≤0.6%) in all groups and similar rate of local adverse effects (around 10%) among the groups except for UHMW HA group (37.5%). Among different MWs of HA for treating hip OA, HMW HA injection demonstrated the best efficacy for up to 6 months after treatment without increased risk of adverse effects. Further studies with more comprehensive data and a higher level of evidence are required to prove our results.

Small-scale distributions of polycyclic aromatic hydrocarbons in urban areas using geospatial modeling: A case study using the moss Orthotrichum lyellii in Portland, Oregon, U.S.A.

Polycyclic aromatic hydrocarbons (PAHs) are widespread pollutants that are costly to measure with air quality instruments. We used a spatially balanced sample of an epiphytic moss, Orthotrichum lyellii, to develop fine-scale maps of atmospheric PAHs across residential areas of Portland, Oregon. The unusual abundance of this stress-tolerant species enabled us to systematically collect a large sample (n = 350) on a 1 × 1km grid across the city. This provided the unique opportunity to investigate potential effects of more than 20 factors on PAH concentrations in moss, including emissions sources, tree canopy cover, relative elevation, short-term weather, and nuance of sample collection. We measured 20 PAHs in moss samples and assigned them to 4 groups for analysis based on molecular weight (MW): the Naphthalene, Low, Medium, and High MW groups. Spatial regression models explained a modest amount of variation in PAH concentrations in moss, with spatial structure increasing as MW increased. Motor vehicle emissions were the only PAH source we detected and was highly significant in all models. Deciduous tree cover correlated with lower PAH concentrations in moss for all except the high MW group. Short-term weather and nuance of sample collection, like height on the sampled tree, tree taxonomic family, and whether sample was primarily collected from a branch or bole, had surprisingly large effects on all groups. Overall, results aligned with expectations based on each group's dispersal potential due to MW. All PAH groups were highest over downtown Portland, along major highways, and lowest in parks and outer neighborhoods, although the details varied. Our results supported two common themes in studies directly measuring PAHs: the importance of roads as an emissions source in residential areas, and the potential for trees to reduce atmospheric concentrations. Moreover, the large effects of weather and sampling nuance have critical implications for the design of future studies.

Airway Inflammatory Responses Following Exposure to Occupational Agents

Airway inflammatory responses to specific inhalation challenges (SICs) with low-molecular-weight (LMW) and high-molecular-weight (HMW) agents have not been studied thoroughly. We assessed the changes in airway inflammatory cells following SIC in sensitized workers, and looked at the influence of various factors on the pattern of inflammatory responses to SIC. Induced sputum analysis was performed in workers sensitized to LMW (n = 41) or HMW agents (n = 41) after a control day and after a positive SIC. Cell counts were compared with lung function and various clinical parameters. In the LMW group, eosinophils were increased following late asthmatic responses (median [interquartile range], 0.02 [0.04] × 10(6) cells/g vs 0.30 [0.80] × 10(6) cells/g and 1.0% [3.5] vs 8.9% [8.0], P < .05), as were neutrophil numbers (0.8 [1.3] × 10(6) cells/g vs 2.3 [5.4] × 10(6) cells/g, P = .04). In the HMW group, eosinophil percentages increased both after early (1.0% [2.2] vs 5.5% [14.5], P = .003) and dual asthmatic responses (4.5% [3.7] vs 15.0% [13.7], P = .02). In the LMW group, the increases in neutrophils were higher in current smokers than in ex-smokers or nonsmokers. The length of exposure to the agent, tobacco use, and baseline percentage of eosinophils were independent predictors of the change in eosinophils, whereas age and baseline neutrophil percentage were predictors of the change in neutrophils. This study confirms that eosinophils and neutrophils are increased after SIC, whatever the causal agent. The type of agent is not predictive of the inflammatory response to SIC. Smoking is associated with a more neutrophilic response after SIC with an LMW agent.

The effects of concentrated barley β-glucan on blood lipids in a population of hypercholesterolaemic men and women

Barley, like oats, is a rich source of the soluble fibre beta-glucan, which has been shown to significantly lower LDL-cholesterol (LDL-C). However, barley foods have been less widely studied. Therefore, we evaluated the LDL-C-lowering effect of a concentrated barley beta-glucan (BBG) extract as a vehicle to deliver this potential health benefit of barley. In a 10-week blinded controlled study, subjects were randomized to one of four treatment groups or control. Treatment groups included either high molecular weight (HMW) or low molecular weight (LMW) BBG at both 3 and 5 g doses. Treatment was delivered twice per day with meals in the form of two functional food products: a ready-to-eat cereal and a reduced-calorie fruit juice beverage. Levels of total cholesterol, LDL-C, HDL-cholesterol (HDL-C), and TAG were determined at baseline and after 6 weeks of treatment. The study group comprised 155 subjects. All treatments were well tolerated and after 6 weeks of treatment the mean LDL-C levels fell by 15 % in the 5 g HMW group, 13 % in the 5 g LMW group and 9 % in both the 3 g/d groups, versus baseline. Similar results were observed for total cholesterol. HDL-C levels were unchanged by treatment. Concentrated BBG significantly improves LDL-C and total cholesterol among moderately dyslipidaemic subjects. Food products containing concentrated BBG should be considered an effective option for improving blood lipids.

Size distributions of water-soluble organic carbon in ambient aerosols and its size-resolved thermal characteristics

Abstract Aerosol mass size distributions of water-soluble organic carbon (WSOC) were studied at a coastal site in Hong Kong. Eleven sets of 72-h samples were collected using an eight-stage impactor sampler over three seasons in 2000–2001. Regardless of air mass origins being mainly marine or continental, WSOC exhibited bimodal size distributions with a dominant fine mode and a minor coarse mode in the size range of >0.43 μm. The two modes had a mass mean aerodynamic diameter (MMAD) of 0.7±0.1 and 4.0±0.3 μm, respectively. The fine WSOC accounted for the major proportion of the total WSOC, ranging from two-thirds to four-fifths. The WSOC mixtures were resolved into 3–5 peaks under controlled progressive heating and combustion conditions. A positive matrix factorization analysis deconvoluted the WSOC mixtures into three component groups of different thermal behaviors. The three groups of WSOC species were postulated to be low, medium, and high molecular weight (MW) polar compounds on the basis of their thermal evolution features. On average, they accounted for 21%, 39%, and 40% of fine WSOC ( 2.1 μm) was largely made of the low MW polar compound group. The low MW group had a bimodal distribution with a dominant coarse mode, likely associated with sea salt aerosols. The medium and the high MW groups had a single mode distribution in the droplet mode, both with an average MMAD of 0.7±0.1 μm. Their droplet mode presence indicated that they were associated with cloud-processed particles. There is evidence to suggest that the high MW group was likely secondary in origin, formed during cloud processing.

Intracellular translocation of cellular and heat shock induced proteins upon heat shock in Drosophila Kc cells.

The intracellular distribution of cellular and heat shock induced proteins (hsp) was studied during a heat shock to Drosophila Kc cells. The different hsp's are unequally distributed between the intracellular organelles; while hsp 84 shows an exclusive cytoplasmic location, hsp 70 is equally distributed between the nucleus and the cytoplasm. The low molecular weight (MW) hsp's 22--26 are mainly concentrated in the nuclear fraction. Hsp 34 also shows a preferential nuclear localization but differs from the 22-26 hsp group with regard to its solubility in salt. During the heat shock (HS) treatment, a major preexisting microsomal polypeptide of relative mass (Mr) 45 000 with some properties similar to cytoskeletal proteins is translocated to the nuclear pellet. This translocation does not occur during arsenite treatment which also induces the synthesis of some hsp's. Furthermore, the hsp's synthesized in response to this arsenite treatment do not become associated with the nucleus as during the HS. Consequently the nuclear translocation of the 45 000 Mr protein does not seem to be involved in the induction of the high MW group of hsp's. Furthermore, it suggests that the hsp's which are found in the nuclear pellet upon HS do not have a nuclear localization per se. It rather reflects a temperature-dependent translocation of certain cellular proteins and hsp to the nucleus during a HS.