A century of trends in adult human height

Being taller is associated with enhanced longevity, and higher education and earnings. We reanalysed 1472 population-based studies, with measurement of height on more than 18.6 million participants to estimate mean height for people born between 1896 and 1996 in 200 countries. The largest gain in adult height over the past century has occurred in South Korean women and Iranian men, who became 20.2 cm (95% credible interval 17.5-22.7) and 16.5 cm (13.3-19.7) taller, respectively. In contrast, there was little change in adult height in some sub-Saharan African countries and in South Asia over the century of analysis. The tallest people over these 100 years are men born in the Netherlands in the last quarter of 20th century, whose average heights surpassed 182.5 cm, and the shortest were women born in Guatemala in 1896 (140.3 cm; 135.8-144.8). The height differential between the tallest and shortest populations was 19-20 cm a century ago, and has remained the same for women and increased for men a century later despite substantial changes in the ranking of countries

Rising rural body-mass index is the main driver of the global obesity epidemic in adults

Body-mass index (BMI) has increased steadily in most countries in parallel with a rise in the proportion of the population who live in cities 1,2 . This has led to a widely reported view that urbanization is one of the most important drivers of the global rise in obesity 3�6 . Here we use 2,009 population-based studies, with measurements of height and weight in more than 112 million adults, to report national, regional and global trends in mean BMI segregated by place of residence (a rural or urban area) from 1985 to 2017. We show that, contrary to the dominant paradigm, more than 55 of the global rise in mean BMI from 1985 to 2017�and more than 80 in some low- and middle-income regions�was due to increases in BMI in rural areas. This large contribution stems from the fact that, with the exception of women in sub-Saharan Africa, BMI is increasing at the same rate or faster in rural areas than in cities in low- and middle-income regions. These trends have in turn resulted in a closing�and in some countries reversal�of the gap in BMI between urban and rural areas in low- and middle-income countries, especially for women. In high-income and industrialized countries, we noted a persistently higher rural BMI, especially for women. There is an urgent need for an integrated approach to rural nutrition that enhances financial and physical access to healthy foods, to avoid replacing the rural undernutrition disadvantage in poor countries with a more general malnutrition disadvantage that entails excessive consumption of low-quality calories. © 2019, The Author(s)

Tribological Properties Of Polyvinyl Alcohol Hydrogels As Artificial Articular Cartilage

An exhaustive scientific investigation has been performed on polymeric hydrogels as potential materials to be used in cartilage tissue repair or replacement. Polyvinyl alcohol (PVA) possesses excellent properties as biocompatibility, low coefficient of friction, low interfacial tension and high permeability to fluids, emerging as an eligible material to be studied for biomedical applications. The main goal of this study was the tribological characterization of PVA hydrogels in lubricated sliding with distilled water and phosphate buffered saline solution (PBS). The influence of hydrogels mechanical properties and operating conditions were considered. Tribological tests were performed on a pin-on-plate tribometer with a linear reciprocating geometry using the PVA/stainless steel 316L and PVA/bovine articular cartilage pairs. Experiments were performed at 37°C with a constant reciprocating sliding frequency of 1 Hz and applied load of 1 MPa, 2 MPa and 3.5 MPa. For each experiment the friction coefficient was determined and the dominating wear mechanisms analysed by scanning electron microscopy and EDS. PVA showed an excellent performance as possible material for the repair of articular cartilage due to the high level of surface preservation and the very low friction coefficient presented when PBS was used as fluid lubricant. The performed tribological study revealed the high potentiality of PVA hydrogels to be used as artificial articular cartilage. © 2012 Nova Science Publishers, Inc. All rights reserved.329342Athanasiou, K.A., Darling, E.M., Hu, J.C., Articular Cartilage Tissue Engineering (2010), Morgan and Claypool PublishersMansour, J.M., Biomechanics of Cartilage. (C.A. Oatis, Ed.) Arthritis and Rheumatism (2008) Lippincott Williams and Wilkins, 58 (7), pp. 2065-2074Seal, B.L., Otero, T.C., Panitch, A., Review: Polymeric biomaterials for tissue and organ regeneration (2001) Materials Science and Engineering R, 34, pp. 147-230Ratner, B.D., Hoffman, A.S., Synthetic hydrogels for biomedical applications (1976), 31, pp. 1-36. , Hydrogels for medical and related applications, ACS Symposium Series, Washington, DCJiang, S., Liu, S., Feng, W., PVA hydrogel properties for biomedical application (2011) Journal of the Mechanical Behaviourof Biomedical Materials, 4, pp. 1228-1233Gang, W.U., Wenguang, Z., Chengtao, W., Tribological properties of polyvinyl alcohol hydrogel reinforced with nanometer hydroxyapatite (2008) Journal of Wuhan University of Technology-Mater. Sci., 23, p. 1Rosiak, J.M., Ulanski, P., Pajewski, L.A., Yoshi, F., Makuuchi, K., Radiation formation of hydrogels for biomedical purposes. Some remarks and comments (1995) Radiation Physics and Chemistry, 46 (2), pp. 161-168Holloway, J.L., Spiller, K.L., Lowman, A.M., Palmese, G.R., Analysis of the in vitro swelling behavior of poly(vinyl alcohol) hydrogels in osmotic pressure solution for soft tissue replacement (2011) Acta Biomaterialia., 7, pp. 2477-2482Pan, Y.S., Xiong, D.S., Ma, R.Y., A study on the friction properties of poly(vinyl alcohol) hydrogel as articular cartilage against titanium alloy (2007) Wear, 262, pp. 1021-1025Pan, Y., Xiong, D., Friction properties of nano-hydroxyapatite reinforced poly(vinyl alcohol) gel composites as an articular cartilage (2009) Wear, 266, pp. 699-703Covert, R.J., Ott, R.D., Ku, D.N., Friction characteristics of a potential articular cartilage biomaterial (2003) Wear, 255, pp. 1064-1068Bavaresco, V.P., Tribological study of polymeric hydrogels for use as artificial articular cartilage (2004), PhD Thesis, State University of Campinas, SP, BrazilZheng, Y., Huang, X., Wang, Y., Xi, T., Chen, X., Xu, H., The surface lubricative properties of PVA/PVP hydrogels treated with radiation used as artificial cartilage (2008) Applied Surface Science, 255, pp. 568-570Bonakdar, S., Emami, S.H., Shokrgozar, M.A., Farhadi, A., Ahmadi, S.A., Amanzadeh, A., Preparation and characterization of polyvinyl alcohol hydrogels crosslinked by biodegradable polyurethane for tissue engineering of cartilage (2010) Materials Science and Engineering C., 30, pp. 636-643Krumova, M., López, D., Benavente, R., Mijangos, C., Pereña, J.M., Effect of crosslinking on the mechanical and thermal properties of poly(vinyl alcohol) (2000) Polymer, 41, pp. 9265-9272Bavaresco, V.P., Zavaglia, C.A., Reis, M.C., Gomes, J.R., Study on the tribological properties of pHEMA hydrogels for use in artificial articular cartilage (2008) Wear, 265, pp. 269-277Gong, J.P., Osada, Y., Surface friction of polymer gels (2002) Progress in Polymer Science., 27, pp. 3-38Bolto, B., Tran, T., Hoang, M., Xie, Z., Crosslinked poly(vinyl alcohol) membranes (2009) Progress in Polymer Science., 34, pp. 969-981Hennink, W.E., Nostrum, C.F., Novel crosslinking methods to design hydrogels (2002) Advanced Drug Delivery Reviews, 54, pp. 12-36Ajji, Z., Preparation of poly(vinyl alcohol) hydrogels containing citric or succinic acid using gamma radiation (2005) Radiation Physics and Chemistry., 74, pp. 36-41Wang, B., Mukataka, S., Kokufuta, E., Kodama, M., The influence of polymer concentration on the radiation-chemical yield of intermolecular crosslinking of poly(vinyl alcohol) by γ-rays in deoxygenated aqueous solution (2000) Radiation Physics and Chemistry., 59, pp. 91-95Wang, B., Kodama, M., Mukataka, S., Kokufuta, E., On the intermolecular crosslinking of PVA chains in an aqueous solution by γ-ray irradiation (1998) Polymer Gels and Networks, 6, pp. 71-81Kempson, G.E., Freeman, M.A.R., Swanson, S.A.V., The determination of a creep modulus for articular cartilage from indentation tests on the human femoral head (1971) Journal of mechanics., 4, pp. 239-250Gong, J.P., Friction and lubrication of hydrogels-its richness and complexity (2006) Soft Matter., 2, pp. 544-552Katta, J., Jin, Z., Ingham, E., Fisher, J., Biotribology of articular cartilage-A review of the recent advances (2008) Medical Engineering and Physics., 30, pp. 1349-1363Graindorge, S.L., Stachowiak, G.W., Changes occurring in the surface morphology of articular cartilage during wear (2000) Wear, 241, pp. 143-150Mow, V.C., Ateshian, G.A., Lubrication and wear of diarthrodial joint. Basic Orthopedic Biomechanics (1997), pp. 275-315. , 2nd edition. Philadelphia: Lippincott-Raven Publisher

The nucleus reuniens: a key node in the neurocircuitry of stress and depression

The hippocampus and prefrontal cortex (PFC) are connected in a reciprocal manner: whereas the hippocampus projects directly to the PFC, a polysynaptic pathway that passes through the nucleus reuniens (RE) of the thalamus relays inputs from the PFC to the hippocampus. The present study demonstrates that lesioning and/or inactivation of the RE reduces coherence in the PFC–hippocampal pathway, provokes an antidepressant-like behavioral response in the forced swim test and prevents, but does not ameliorate, anhedonia in the chronic mild stress (CMS) model of depression. Additionally, RE lesioning before CMS abrogates the well-known neuromorphological and endocrine correlates of CMS. In summary, this work highlights the importance of the reciprocal connectivity between the hippocampus and PFC in the establishment of stress-induced brain pathology and suggests a role for the RE in promoting resilience to depressive illness. © 2018, Macmillan Publishers Limited, part of Springer Nature

Heterogeneous contributions of change in population distribution of body mass index to change in obesity and underweight

From 1985 to 2016, the prevalence of underweight decreased, and that of obesity and severe obesity increased, in most regions, with significant variation in the magnitude of these changes across regions. We investigated how much change in mean body mass index (BMI) explains changes in the prevalence of underweight, obesity, and severe obesity in different regions using data from 2896 population-based studies with 187 million participants. Changes in the prevalence of underweight and total obesity, and to a lesser extent severe obesity, are largely driven by shifts in the distribution of BMI, with smaller contributions from changes in the shape of the distribution. In East and Southeast Asia and sub-Saharan Africa, the underweight tail of the BMI distribution was left behind as the distribution shifted. There is a need for policies that address all forms of malnutrition by making healthy foods accessible and affordable, while restricting unhealthy foods through fiscal and regulatory restrictions. © Copyright