scholarly journals Bone metabolism and nutritional status during 30-day head-down-tilt bed rest

2012 ◽  
Vol 113 (10) ◽  
pp. 1519-1529 ◽  
Author(s):  
Jennifer L. L. Morgan ◽  
Sara R. Zwart ◽  
Martina Heer ◽  
Robert Ploutz-Snyder ◽  
Karen Ericson ◽  
...  
Keyword(s):  
Nutritional Status ◽  
Oxidative Damage ◽  
Bone Metabolism ◽  
Short Duration ◽  
Iron Status ◽  
A Priori ◽  
Bed Rest ◽  
Urinary Calcium ◽  
Bone Biochemistry ◽  
Urinary Oxalate Excretion

Bed rest studies provide an important tool for modeling physiological changes that occur during spaceflight. Markers of bone metabolism and nutritional status were evaluated in 12 subjects (8 men, 4 women; ages 25–49 yr) who participated in a 30-day −6° head-down-tilt diet-controlled bed rest study. Blood and urine samples were collected twice before, once a week during, and twice after bed rest. Data were analyzed using a mixed-effects linear regression with a priori contrasts comparing all days to the second week of the pre-bed rest acclimation period. During bed rest, all urinary markers of bone resorption increased ∼20% ( P < 0.001), and serum parathyroid hormone decreased ∼25% ( P < 0.001). Unlike longer (>60 days) bed rest studies, neither markers of oxidative damage nor iron status indexes changed over the 30 days of bed rest. Urinary oxalate excretion decreased ∼20% during bed rest ( P < 0.001) and correlated inversely with urinary calcium ( R = −0.18, P < 0.02). These data provide a broad overview of the biochemistry associated with short-duration bed rest studies and provide an impetus for using shorter studies to save time and costs wherever possible. For some effects related to bone biochemistry, short-duration bed rest will fulfill the scientific requirements to simulate spaceflight, but other effects (antioxidants/oxidative damage, iron status) do not manifest until subjects are in bed longer, in which case longer studies or other analogs may be needed. Regardless, maximizing research funding and opportunities will be critical to enable the next steps in space exploration.

Circulating Proteins and Iron Status in Blood as Indicators of the Nutritional Status of 10- to 12-Year-Old Bolivian Boys

1994 ◽  
Vol 15 (S 2) ◽  
pp. S79-S83 ◽  
Author(s):  
W. Téllez ◽  
J. San Miguel ◽  
A. Rodriguez ◽  
M. Chavez ◽  
C. Lujan ◽  
...  
Keyword(s):  
Nutritional Status ◽  
Iron Status

Calcium and Iron Absorption - Mechanisms and Public Health Relevance

2010 ◽  
Vol 80 (45) ◽  
pp. 293-299 ◽  
Author(s):  
Bo Lönnerdal
Keyword(s):  
Short Duration ◽  
Human Subjects ◽  
Iron Status ◽  
Basolateral Membrane ◽  
Rebound Effect ◽  
Inhibitory Effect ◽  
Compensatory Mechanisms ◽  
Divalent Metal Transporter 1 ◽  
Divalent Metal Transporter ◽  
Fe Uptake

Studies on human subjects have shown that calcium (Ca) can inhibit iron (Fe) absorption, regardless of whether it is given as Ca salts or in dairy products. This has caused concern as increased Ca intake commonly is recommended for children and women, the same populations that are at risk of Fe deficiency. However, a thorough review of studies on humans in which Ca intake was substantially increased for long periods shows no changes in hematological measures or indicators of iron status. Thus, the inhibitory effect may be of short duration and there also may be compensatory mechanisms. The interaction between Ca and Fe may be a lumenal event, affecting Fe uptake through DMT1 (divalent metal transporter 1) at the apical membrane. However, it is also possible that inhibition occurs during Fe transfer into circulation, suggesting roles for the serosal exporter ferroportin (FPN) and hephaestin. We explored these possibilities in human intestinal Caco-2 cells cultured in monolayers. Iron transport (59Fe) and expression of DMT1, FPN, and hephaestin were assessed after 1.5 and 4 hours with 0 or 100 µM CaCl2. Although Ca did not affect Fe uptake or DMT1 expression at 1.5 hours, FPN abundance at the basolateral membrane decreased, resulting in increased cellular Fe retention and decreased Fe efflux. After 4 hours, DMT1 and FPN expression increased and there was increased FPN at the membrane, suggesting a rebound effect. Thus, the effect of Ca on Fe absorption may be of short duration and adaptation may occur with time. This may explain why studies on long-term Ca supplementation of different groups fail to show any adverse effects on Fe status.

Bone biochemistry and bone metabolism in patients with Crohns disease

2000 ◽  
Vol 118 (4) ◽  
pp. A316
Author(s):  
Sarah A. Bartram ◽  
Robert Peaston ◽  
Roger M. Francis ◽  
Nick P. Thompson
Keyword(s):  
Bone Metabolism ◽  
Crohns Disease ◽  
Bone Biochemistry

Impact of the WIC Program on the Iron Status of Infants

PEDIATRICS ◽  
1985 ◽  
Vol 75 (1) ◽  
pp. 100-105 ◽  
Author(s):  
Virginia Miller ◽  
Sheldon Swaney ◽  
Amos Deinard
Keyword(s):  
Socioeconomic Status ◽  
Iron Deficiency ◽  
Nutritional Status ◽  
Pregnant Women ◽  
Iron Status ◽  
Deficiency Anemia ◽  
Wic Program ◽  
Lactating Women ◽  
Supplemental Food ◽  
Women And Children

The WIC Program (Special Supplemental Food Program for Women, Infants and Children) was initiated in the early 1970s to improve the nutritional status of pregnant women, lactating women, and children from birth to 5 years of age who were at risk for nutritionally related health problems. Better hematologic status of a group of preschool-aged infants who were enrolled in the WIC Program from birth, as compared with another group of similar age and socioeconomic status from the pre-WIC Program era, suggests that participation in the WIC Program will help limit the development of iron depletion or iron deficiency anemia in young children, an important consideration in view of the deleterious hematologic and nonhematologic effects that have been attributed to those conditions.

Short-term and long-term variability of indices related to nutritional status. I: Ca, Cu, Fe, Mg, and Zn.

1989 ◽  
Vol 35 (3) ◽  
pp. 369-373 ◽  
Author(s):  
S K Gallagher ◽  
L K Johnson ◽  
D B Milne
Keyword(s):  
Superoxide Dismutase ◽  
Nutritional Status ◽  
Iron Status ◽  
Short Term ◽  
Free Living ◽  
Analytical Technique ◽  
Metabolic Unit ◽  
Biological Component ◽  
Analytical Variation

Abstract Five free-living women (ages 28-38 y) and five women (ages 23-44 y) residing in a metabolic unit and eating a constant diet were assessed for variation in indices related to mineral nutrition. Blood was sampled once a month for five months, once a week for five weeks, and once a day for five days to assess analytical and biological variability. Analytical variability was determined by using concurrently run duplicate control samples prepared from plasma or serum pools. Of the measured indices, serum ferritin varied most, with intra-individual variance of 4.72% to 18.0%. Much of this variance may have been because of changes in iron status or in the analytical technique used. Intra-individual month-to-month variance for other indices ranged from 17% for superoxide dismutase (EC 1.15.1.1) to 1.5% for calcium. Correction for long-term analytical variation indicated that most of the variance was associated with the biological component. The higher biological variabilities of some indices, including ferritin or superoxide dismutase, need to be considered when nutritional status is being evaluated or when serial observations are made over a protracted period in clinical studies or trials.

scholarly journals Effects of 21 days of bed rest, with or without artificial gravity, on nutritional status of humans

2009 ◽  
Vol 107 (1) ◽  
pp. 54-62 ◽  
Author(s):  
S. R. Zwart ◽  
G. E. Crawford ◽  
P. L. Gillman ◽  
G. Kala ◽  
A. S. Rodgers ◽  
...  
Keyword(s):  
Nutritional Status ◽  
Rest Period ◽  
Nutrient Status ◽  
Bed Rest ◽  
Blood Chemistry ◽  
Artificial Gravity ◽  
Blood Levels ◽  
Negative Effects ◽  
Vitamin Status ◽  
Β Carotene

Spaceflight and bed rest models of microgravity have profound effects on physiological systems, including the cardiovascular, musculoskeletal, and immune systems. These effects can be exacerbated by suboptimal nutrient status, and therefore it is critical to monitor nutritional status when evaluating countermeasures to mitigate negative effects of spaceflight. As part of a larger study to investigate the usefulness of artificial gravity as a countermeasure for musculoskeletal and cardiovascular deficits during bed rest, we tested the hypothesis that artificial gravity would have an effect on some aspects of nutritional status. Dietary intake was recorded daily before, during, and after 21 days of bed rest with artificial gravity ( n = 8) or bed rest alone ( n = 7). We examined body composition, hematology, general blood chemistry, markers of oxidative damage, and blood levels of selected vitamins and minerals before, during, and after the bed rest period. Several indicators of vitamin status changed in response to diet changes: serum α- and γ-tocopherol and urinary 4-pyridoxic acid decreased ( P < 0.001) and plasma β-carotene increased ( P < 0.001) in both groups during bed rest compared with before bed rest. A decrease in hematocrit ( P < 0.001) after bed rest was accompanied by a decrease in transferrin (P < 0.001), but transferrin receptors were not changed. These data provide evidence that artificial gravity itself does not negatively affect nutritional status during bed rest. Likewise, artificial gravity has no protective effect on nutritional status during bed rest.

scholarly journals Association of urinary sex steroid hormones with urinary calcium, oxalate and citrate excretion in kidney stone formers

2020 ◽  
Author(s):  
Daniel G Fuster ◽  
Gaétan A Morard ◽  
Lisa Schneider ◽  
Cedric Mattmann ◽  
David Lüthi ◽  
...  
Keyword(s):  
Calcium Oxalate ◽  
Kidney Stone ◽  
Urinary Calcium ◽  
Sex Hormone ◽  
Urinary Oxalate ◽  
Oxalate Excretion ◽  
Stone Formers ◽  
17Β Estradiol ◽  
Urinary Citrate ◽  
Urinary Oxalate Excretion

Abstract Background Sex-specific differences in nephrolithiasis with respect to both distribution of prevalence and stone composition are widely described and may be influenced by sex hormones. Methods We conducted a cross-sectional analysis of the relationship between 24-hour urinary sex hormone metabolites measured by gas chromatography–mass spectrometry with urinary calcium, oxalate and citrate excretion in a cohort of 628 kidney stone formers from a tertiary care hospital in Switzerland, taking demographic characteristics, kidney function and dietary factors into account. Results We observed a positive association of urinary calcium with urinary testosterone and 17β-estradiol. Positive associations of urinary calcium with dehydroepiandrosterone, 5α-DH-testosterone, etiocholanolone, androsterone, and estriol were modified by net gastrointestinal alkali absorption or urinary sulfate excretion. As the only sex hormone, dehydroepiandrosterone was inversely associated with urinary oxalate excretion in adjusted analyses. Urinary citrate correlated positively with urinary testosterone. Associations of urinary citrate with urinary androsterone, 17β-estradiol and estriol were modified by urinary sulfate or sodium, or by sex. Conclusions Urinary androgens and estrogens are significantly associated with urinary calcium and citrate excretion, and associations are in part modified by diet. Our data furthermore reveal dehydroepiandrosterone as a novel factor associated with urinary oxalate excretion in humans.

Iron Status Independently Associates With Bone Mineral Density At Population Level. Insights From The Val Borbera Study

Blood ◽  
2013 ◽  
Vol 122 (21) ◽  
pp. 4672-4672
Author(s):  
Nicola Martinelli ◽  
Michela Traglia ◽  
Fabiana Busti ◽  
Marcella Sirtori ◽  
Natascia Campostrini ◽  
...  
Keyword(s):  
Bone Loss ◽  
Bone Mass ◽  
Iron Overload ◽  
Bone Metabolism ◽  
Iron Status ◽  
Population Level ◽  
Mineral Density ◽  
Major Health Problem ◽  
T Score ◽  
Serum Hepcidin

Background and Aims Osteoporosis is a multifactorial major health problem affecting over 200 million people worldwide. It is long known as a complication of marked iron overload, both primary (i.e. genetic hemochromatosis) and secondary (i.e. transfusional iron overload), but only recently cellular and animal models have shed some light on the pathogenetic link between iron and bone metabolism. Iron has been shown to activate osteoclasts (Ishii KA, Nat Med 2009) and to inhibit osteoblasts (Yamasaki K, Toxicol Lett 2009), which express ferroportin regulated by hepcidin (Xu Y, Inflammation 2012). A murine model has shown that iron overload causes bone loss through induction of Reactive Oxygen Species (ROS) (Tsay J, Blood 2010). Of note, a recent longitudinal study in a Korean population has demonstrated that serum ferritin, even at concentrations generally not considered as “iron overload”, is an independent predictor of bone mass deterioration and incident vertebral fractures (Kim BJ, J Bone Miner Res 2012), an effect most prominent in women ≥ 45 years of age (Kim BJ, Osteoporos Int 2013). Taking advantage from the recently completed iron section of the Val Borbera Study (Traglia M, J Med Genet 2011), this study aimed to evaluate for the first time the association between iron status (including serum hepcidin levels) and bone mass in a Caucasian population. Subjects and Methods This survey included 921 subjects (564 females, 357 males) aged 53.8 ± 16.3 years for whom complete data regarding bone mass (measured by transportable Quantitative Ultrasonography, QUS-based approach) and iron status (including serum hepcidin-25 levels measured by Mass Spectrometry) were available. Subjects with known inflammatory and renal disorders, as well as hereditary hemochromatosis had been previously excluded. Analyses were performed separately in males and females, due to known gender-related differences in either iron or bone metabolism. Main Results No significant association was found in males, while in females both ferritin (r= -0.42, P<0.001) and hepcidin (r= -0.30, P<0.001) were inversely correlated with T-score at univariate analyses. However, after including both ferritin and hepcidin in an age-adjusted linear regression model, only ferritin remained a significant predictor of T-score variability (beta coefficient= -0.115, P=0.042). Subsequent regression models adjusted for age, BMI, and C-Reactive Protein highlighted ferritin levels as independent predictors of T-score in females. After stratification for age and ferritin categories, T-score decreased linearly with increasing ferritin levels especially in females aged 50-75 years (n=293), i.e. the age known to be at major risk of accelerated bone loss (P<0.001 – Figure 1). Conclusions This study confirms that iron status significantly associates with bone loss at population level even in Caucasians, particularly in post-menopausal women. Increasing iron stores, even not clearly “pathologic”, may influence bone metabolism through increased ROS and/or hepcidin-mediated altered iron handling of osteoblasts and osteoclasts. Disclosures: No relevant conflicts of interest to declare.

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