| 1. |
- Lind, Lars, et al.
(författare)
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Heterogeneous contributions of change in population distribution of body mass index to change in obesity and underweight NCD Risk Factor Collaboration (NCD-RisC)
- 2021
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Ingår i: eLife. - : eLife Sciences Publications Ltd. - 2050-084X. ; 10
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Tidskriftsartikel (refereegranskat)abstract
- 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.
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| 2. |
- Bixby, H., et al.
(författare)
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Rising rural body-mass index is the main driver of the global obesity epidemic in adults
- 2019
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Ingår i: Nature. - : Springer Science and Business Media LLC. - 0028-0836 .- 1476-4687. ; 569:7755, s. 260-4
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Tidskriftsartikel (refereegranskat)abstract
- 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.
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| 3. |
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| 4. |
- Mishra, A, et al.
(författare)
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Diminishing benefits of urban living for children and adolescents' growth and development
- 2023
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Ingår i: Nature. - : Springer Science and Business Media LLC. - 1476-4687 .- 0028-0836. ; 615:7954, s. 874-883
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Tidskriftsartikel (refereegranskat)abstract
- Optimal growth and development in childhood and adolescence is crucial for lifelong health and well-being1–6. Here we used data from 2,325 population-based studies, with measurements of height and weight from 71 million participants, to report the height and body-mass index (BMI) of children and adolescents aged 5–19 years on the basis of rural and urban place of residence in 200 countries and territories from 1990 to 2020. In 1990, children and adolescents residing in cities were taller than their rural counterparts in all but a few high-income countries. By 2020, the urban height advantage became smaller in most countries, and in many high-income western countries it reversed into a small urban-based disadvantage. The exception was for boys in most countries in sub-Saharan Africa and in some countries in Oceania, south Asia and the region of central Asia, Middle East and north Africa. In these countries, successive cohorts of boys from rural places either did not gain height or possibly became shorter, and hence fell further behind their urban peers. The difference between the age-standardized mean BMI of children in urban and rural areas was <1.1 kg m–2 in the vast majority of countries. Within this small range, BMI increased slightly more in cities than in rural areas, except in south Asia, sub-Saharan Africa and some countries in central and eastern Europe. Our results show that in much of the world, the growth and developmental advantages of living in cities have diminished in the twenty-first century, whereas in much of sub-Saharan Africa they have amplified.
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| 6. |
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| 7. |
- Fransén, Erik, 1962-, et al.
(författare)
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Computational modeling of activity dependent velocity changes in peripheral C-fibers
- 2011
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Konferensbidrag (refereegranskat)abstract
- Initiation and propagation of action potentials along unmyelinated C-fibers are the first steps of the pain pathway. Propagation velocity and its fiber class-specific activity-dependent slowing (ADS) is intimately linked to fibre excitability. In chronic pain patients, ADS alterations have been suggested to reflect increased excitability, possibly underlying clinical pain. Due to their small diameter, peripheral axons of nociceptors in patients are not accessible for intraaxonal recordings of their ion channel properties. We have therefore constructed a model of a C-fibre to study the relationship between ion channel composition and velocity changes as well as excitability. Ion channels are modeled from data of DRG somata using a Hodgkin-Huxley formalism (Na currents: TTX-sensitive, Nav1.8, Nav1.9, K currents: Kdr, A-type, Kv7.3, non-specific cationic: HCN). Moreover, ion pumps (Na/K-ATPase) and concentrations of intra and extraaxonal sodium and potassium are also included. The geometry and temperature of the fibre represents a section of the superficial branch and the deeper parent and is represented by a multicompartmental structure where each compartment contains passive as well as ion channel and pump elements. Using parameter estimation techniques, we optimized ion channel and pump expression pattern such that basic electrophysiological characteristics of the action potential and its velocity matched the experimental data. Moreover, we have also replicated activity dependent slowing. In ongoing work, we extend optimization to also include recovery cycles. The model will be used to study hypothesis of the relationship between individual ion channel subtypes and axonal excitability related to pain, generating independent information on impact of selective neuronal targets.
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| 8. |
- Fransén, Erik, 1962-, et al.
(författare)
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Differences in action potential propagation in mechanosensitive and insensitive C-nociceptors - a modeling approach
- 2012
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Konferensbidrag (refereegranskat)abstract
- C-fibers, unmyelinated afferent axons, convey information from the periphery of the nervous system to the spinal cord. They transmit signals originating from noxious stimulation evoking the sensations of itch and pain in the central nervous system. Different classes of C-fibers are characterized by functional, morphological and biochemical characteristics. In pain studies, a classification into mechano-insensitive (CMi) and mechano responsive fibers (CM) has proven useful as changes in proportions and response characteristics of these fibers have been observed in neuropathy patients (Weidner et al. 1999, 2000; Orstavik 2003, 2010). In this study, using computational modeling of a C-fiber, we have studied the possible contribution of different ion channel subtypes (Na-TTXs, Nav1.8, Nav1.9, Kdr, KA, KM, K(Na), h) as well as the Na/K-ATPase pump to conductive properties of C-fibers. In particular we investigated mechanisms that could generate the fiber-specific differences between CM and CMi fibers with regard to activity dependent slowing (ADS) and recovery cycles (RC). In our study we represent the axon by three cylindrical sections, one representing the peripheral thin end (branch, 2.5 cm), one the central part (parent, 10 cm) and a conical section between these (0.5 cm). In total 730 compartments are used. Temperature is set to 32 degrees C in branch and 37 degrees in parent sections. We represent variable ion concentrations of Na and K intra axonally, periaxonally and extracellularly, from which reversal potentials are calculated. We use ion channel models based on Hodgkin Huxley formalism. An ion pump (Na/K-ATPase) is included. We find that TTX-sensitive Na and Nav1.8 have the strongest influence on action potential conduction velocity as is expected since these are the major components of the rising phase of the action potential. Preliminary observations indicate that a small subset of Na and K currents play a key role in determining differences in activity dependent velocity changes (ADS) in the two fiber classes. We plan to also study contributions from morphological characteristics (superficial branch lengths) to activity dependent differences between the fiber classes (Schmidt et al. 2002). We further intend to investigate candidate ion channels which could play a role in changing the functional characteristics of a CMi fiber to that of a CM fiber. Our studies may provide insights into ionic changes underlying changes in the excitability of C-fibers associated with pain.
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