Bone Marker, Hematology, and Nutrition is one of eleven International Bedrest Standard Measures conducted on healthy subjects at the :envihab facility in Cologne, Germany. Bone turnover markers suggest that bed rest increases bone degradation but has minimal impact on bone formation. General chemistries provide an overview of crew member health. The purpose of the standard measures project is to populate a repository with data that enables high-level monitoring of countermeasure effectiveness and meaningful interpretation of health and performance outcomes. These standard measures will support future, hypothesis-driven research that enables planetary missions by providing an optimized minimal set of measures captured from subjects. These measures will be available to other studies under data sharing agreements as well as undergo analysis to understand risk posture.
APPROACH:
Bone Marker:
Biological samples will be used for determination of bone mineral, nutritional, and clinical status. Circulating bone- and calcium related factors (such as parathyroid hormone [PTH], bone-specific alkaline phosphatase [BSAP], and osteocalcin) will be assessed in serum. Urine samples will be analyzed for collagen crosslinks using commercially available kits. Calcium assessments will be conducted on blood and urine samples. Whole-blood ionized calcium and pH are determined electrochemically using a portable analyzer. Serum total calcium and urinary calcium are determined using atomic absorption spectrophotometry. Serum 1, 25 dihydroxyvitamin D is measured by radioimmunoassay (RIA) after acetonitrile extraction. Endocrine factors that regulate and affect bone will also be determined, to provide a complete profile of bone and calcium regulation and understand the effects of the countermeasures. These factors include testosterone, dehydroepiandrosterone (DHEA), dehydroepiandrosterone sulfate (DHEA-S), cortisol, estradiol, thyroxine (free T4), and thyroid stimulating hormone.
Nutrition/Hematology:
Serum chemistry and hematology analyses will be conducted using standard clinical techniques. Serum electrolytes, total protein, total cholesterol, triglycerides, albumin, transferrin, liver enzymes, urinary magnesium, and total alkaline phosphate will be assayed using an automated clinical chemistry system. Ionized calcium (iCa), pH, and the partial pressures of carbon dioxide and oxygen will be analyzed in whole blood from venous or finger-stick blood samples. Fibrinogen is measured by nephelometry using a BN2 analyzer. Urinary creatinine and phosphorus are measured spectrophotometrically using an ACE Alera clinical chemistry system. Urine pH will be determined using a pH meter.
Hemoglobin, hematocrit, and mean corpuscular volume will be determined using a Coulter LH750 instrument. Serum ferritin will be analyzed using the Advia Centaur XP immunoassay system. Standard clinical techniques are used for determining transferrin and total-iron binding capacity (TIBC). Transferrin receptors will be determined using a commercially available ELISA. Iron and ferritin iron content and concentration will be determined by inductively-coupled plasma mass spectrometry (ICP-MS).
Calcium status is assessed via analytes of blood and urine samples. Whole-blood ionized calcium and pH is determined by ion-specific electrometry performed with a portable analyzer. Serum total calcium and urinary calcium are determined using atomic spectrophotometry. Endocrine factors are analyzed by liquid chromatography with tandem mass spectrometry, ELISA, or RIA procedures. Cytokines are measured using ELISAs.
The renal stone risk profile is a panel of measures including urinary pH, sodium, potassium, calcium, oxalate, citrate, total volume. Phosphorus, magnesium, uric acid, and sulfate. Supersaturation values are calculated from the panel using multistix 10SG reagent strips which are run on a Clinitek analyzer for urinalysis of protein, pH, color, specific gravity, glucose, bilirubin, ketone, blood, urobilinogen, nitrite, and leukocyte esterase.
Serum ceruloplasmin, retinol-binding protein, and transthyretin are analyzed by nephelometry with a BN2 analyzer. Assay of urinary 3-methylhistidine is performed by ion-exchange chromatography on a Hitachi L8800 amino acid analyzer. Urinary nitrogen is analyzed by pyrochemiluminescence using an Antek 7000 analyzer.
One-carbon metabolism is assessed through analysis of a homocysteine metabolite panel. The red blood count (RBC) transaminase, glutathione reductase and tranketolase assays are analyzed spectrophotometrically on the ACE Alera clinical chemistry system. RBC folate and serum folate are measured using a commercially available radioreceptor assay. Plasma pyridoxal 5’-phosphate and 4-pyridoxic acid are measured by high-performance liquid chromatography (HPLC). Samples for analysis of plasma homocysteine are analyzed by Metabolite Laboratories for gas chromatography-mass spectrometry. Vitamin C is analyzed by HPLC.
Serum 1,25 dihydroxyvitamin D is measured by RIA after extraction of samples with acetonitrile and purification on C18OH cartridges, and serum 25 hydroxyvitamin D is determine by RIA after acetonitrile extraction. Vitamin D-binding protein and plasma heme are assayed as previously described using commercially available kits.
The scheduled days of collection are as follows:
- Three days prior to mission (BDC-3)
- The day mission ends (R+0)
RESULTS:
The :envihab International Bedrest Standard Measures Test Battery is not a hypothesis-driven study, but rather a collection of data made available to future researchers and for trend analysis. As such, there are no specific hypotheses, outcome measures, or statistical analyses associated with the skeleton of the project. The questionnaire will capture a "snapshot" of optimized data that can be investigated by researchers in the future.
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