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Obeid R, Schön C, Wilhelm M, Shrestha RP, Pilz S, Pietrzik K. Response of Red Blood Cell Folate to Supplementation in Nonpregnant Women is Predictable: A Proposal for Personalized Supplementation. Mol Nutr Food Res 2018; 62:1700537. [PMID: 29143484 PMCID: PMC5838518 DOI: 10.1002/mnfr.201700537] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/20/2017] [Revised: 09/25/2017] [Indexed: 11/07/2022]
Abstract
SCOPE We modeled red blood cell (RBC)-folate response to supplementation and developed personalized folate supplementation concepts. METHODS AND RESULTS The changes of RBC-folate were modeled in a time- (4 or 8 weeks) and dose- (400 or 800 μg d-1 folate) dependent manner. Post-supplementation RBC-folate levels were predicted from folate-loading capacities (= measured RBC-folate - [baseline RBC-folate × RBC-survival]). The prediction equations were validated in 119 participants. The median increase of RBC-folate was higher in the 800 μg d-1 than in the 400 μg d-1 group (275 vs 169 nmol L-1 after 4 weeks, and 551 vs 346 nmol L-1 after 8 weeks). Medians (interquartile range) of RBC-folate loading were (4 weeks: 299 (160) vs 409 (237) nmol L-1 ) and (8 weeks: 630 (134) versus 795 (187) nmol L-1 ) in the 400 and 800 μg d-1 group, respectively. The individual measured and predicted RBC-folate values (after 4 weeks/400 μg d-1 = 25 + 1.27 × baseline RBC-folate) and (after 4 weeks/800 μg d-1 = 65 + 1.41 × baseline RBC-folate) did not differ significantly. The measured and predicted concentrations showed high agreement in the validation cohort. CONCLUSIONS The models can guide nutritional recommendations in women when baseline RBC-folate concentrations are measured and the time to pregnancy between 4 and 8 weeks.
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Affiliation(s)
- Rima Obeid
- Department of Clinical ChemistrySaarland University HospitalHomburgGermany
- Aarhus Institute of Advanced StudiesUniversity of AarhusAarhus CDenmark
| | | | - Manfred Wilhelm
- Department of Mathematics, Natural and Economic SciencesUniversity of Applied Sciences UlmUlmGermany
| | | | - Stefan Pilz
- Division of Endocrinology and DiabetologyDepartment of Internal MedicineMedical University of GrazGrazAustria
| | - Klaus Pietrzik
- Department of Nutrition and Food ScienceRheinische Friedrich‐Wilhelms UniversityBonnGermany
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Shrestha RP, Horowitz J, Hollot CV, Germain MJ, Widness JA, Mock DM, Veng-Pedersen P, Chait Y. Models for the red blood cell lifespan. J Pharmacokinet Pharmacodyn 2016; 43:259-74. [PMID: 27039311 PMCID: PMC4887310 DOI: 10.1007/s10928-016-9470-4] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/08/2015] [Accepted: 03/06/2016] [Indexed: 10/22/2022]
Abstract
The lifespan of red blood cells (RBCs) plays an important role in the study and interpretation of various clinical conditions. Yet, confusion about the meanings of fundamental terms related to cell survival and their quantification still exists in the literature. To address these issues, we started from a compartmental model of RBC populations based on an arbitrary full lifespan distribution, carefully defined the residual lifespan, current age, and excess lifespan of the RBC population, and then derived the distributions of these parameters. For a set of residual survival data from biotin-labeled RBCs, we fit models based on Weibull, gamma, and lognormal distributions, using nonlinear mixed effects modeling and parametric bootstrapping. From the estimated Weibull, gamma, and lognormal parameters we computed the respective population mean full lifespans (95 % confidence interval): 115.60 (109.17-121.66), 116.71 (110.81-122.51), and 116.79 (111.23-122.75) days together with the standard deviations of the full lifespans: 24.77 (20.82-28.81), 24.30 (20.53-28.33), and 24.19 (20.43-27.73). We then estimated the 95th percentiles of the lifespan distributions (a surrogate for the maximum lifespan): 153.95 (150.02-158.36), 159.51 (155.09-164.00), and 160.40 (156.00-165.58) days, the mean current ages (or the mean residual lifespans): 60.45 (58.18-62.85), 60.82 (58.77-63.33), and 57.26 (54.33-60.61) days, and the residual half-lives: 57.97 (54.96-60.90), 58.36 (55.45-61.26), and 58.40 (55.62-61.37) days, for the Weibull, gamma, and lognormal models respectively. Corresponding estimates were obtained for the individual subjects. The three models provide equally excellent goodness-of-fit, reliable estimation, and physiologically plausible values of the directly interpretable RBC survival parameters.
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Affiliation(s)
- Rajiv P Shrestha
- Octet Research Inc., 101 Arch St. Suite 1950, Boston, MA, 02110, USA.
| | - Joseph Horowitz
- Department of Mathematics & Statistics, University of Massachusetts, Amherst, MA, 01003, USA
| | - Christopher V Hollot
- Department of Electrical & Computer Engineering, University of Massachusetts, Amherst, MA, 01003, USA
| | - Michael J Germain
- Renal and Transplant Associates of New England, Division of Nephrology, Baystate Medical Center, Tufts University School of Medicine, Boston, MA, USA
| | - John A Widness
- Department of Pediatrics, College of Medicine, The University of Iowa, Iowa City, IA, 52242, USA
| | - Donald M Mock
- Department of Biochemistry and Molecular Biology, University of Arkansas for Medical Sciences, Little Rock, AR, 72205, USA
| | - Peter Veng-Pedersen
- Division of Pharmaceutics, College of Pharmacy, The University of Iowa, Iowa City, IA, 52242, USA
| | - Yossi Chait
- Department of Mechanical & Industrial Engineering, University of Massachusetts, Amherst, MA, 01003, USA
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Chait Y, Horowitz J, Nichols B, Shrestha RP, Hollot CV, Germain MJ. Control-relevant erythropoiesis modeling in end-stage renal disease. IEEE Trans Biomed Eng 2013; 61:658-64. [PMID: 24235247 DOI: 10.1109/tbme.2013.2286100] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
Anemia is prevalent in end-stage renal disease (ESRD). The discovery of recombinant human erythropoietin (rHuEPO) over 30 years ago has shifted the treatment of anemia for patients on dialysis from blood transfusions to rHuEPO therapy. Many anemia management protocols (AMPs) used by clinicians comprise a set of experience-based rules for weekly-to-monthly titration of rHuEPO doses based on hemoglobin (Hb) measurements. In order to facilitate the design of an AMP using model-based feedback control theory, we present a physiologically relevant erythropoiesis model and demonstrate its applicability using clinical data.
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Cabal A, Mehta K, Ross DS, Shrestha RP, Comisar W, Denker A, Pai SM, Ishikawa T. A semimechanistic model of the time-course of release of PTH into plasma following administration of the calcilytic JTT-305/MK-5442 in humans. J Bone Miner Res 2013; 28:1830-6. [PMID: 23436611 DOI: 10.1002/jbmr.1900] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/01/2012] [Revised: 01/31/2013] [Accepted: 02/11/2013] [Indexed: 11/06/2022]
Abstract
JTT-305/MK-5442 is a calcium-sensing receptor (CaSR) allosteric antagonist being investigated for the treatment of osteoporosis. JTT-305/MK-5442 binds to CaSRs, thus preventing receptor activation by Ca(2+) . In the parathyroid gland, this results in the release of parathyroid hormone (PTH). Sharp spikes in PTH secretion followed by rapid returns to baseline are associated with bone formation, whereas sustained elevation in PTH is associated with bone resorption. We have developed a semimechanistic, nonpopulation model of the time-course relationship between JTT-305/MK-5442 and whole plasma PTH concentrations to describe both the secretion of PTH and the kinetics of its return to baseline levels. We obtained mean concentration data for JTT-305/MK-5442 and whole PTH from a multiple dose study in U.S. postmenopausal women at doses of 5, 10, 15, and 20 mg. We hypothesized that PTH is released from two separate sources: a reservoir that is released rapidly (within minutes) in response to reduction in Ca(2+) binding, and a second source released more slowly following hours of reduced Ca(2+) binding. We modeled the release rates of these reservoirs as maximum pharmacologic effect (Emax ) functions of JTT-305/MK-5442 concentration. Our model describes both the dose-dependence of PTH time of occurrence for maximum drug concentration (Tmax ) and maximum concentration of drug (Cmax ), and the extent and duration of the observed nonmonotonic return of PTH to baseline levels following JTT-305/MK-5442 administration.
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Affiliation(s)
- Antonio Cabal
- Early Stage Development ESD - Modeling and Simulations, Merck and Co., Upper Gwynedd, PA, USA
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Aziz AA, Chi HT, Dauphinee W, Davenport D, Gonzales R, Jaeger H, Kipor GV, Mares CA, Shrestha RP, Yoshinaga K. Theme 4. Effective Models for Medical and Health Response Coordination: Summary and Action Plan. Prehosp Disaster Med 2012; 16:33-5. [PMID: 11367937 DOI: 10.1017/s1049023x0002553x] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
AbstractIntroduction:To effectively respond to this relatively new, complex mandate it is essential to find effective models of coordination to ensure that medical and health services can meet the standards now expected in a disaster situation. This theme explored various models, noting both the strengths that can be built on and the weaknesses that still need to be overcome.Methods:Details of the methods used are provided in the preceding paper. The chairs moderated all presentations and produced a summary that was presented to an assembly of all of the delegates. Since the findings from the Theme 1 and Theme 4 groups were similar, the chairs of both groups presided over one workshop that resulted in the generation of a set of Action Plans that then were reported to the collective group of all delegates.Results:The main points developed during the presentations and discussion included: (1) preplanning (predisaster goals), (2) information collection (assessment), (3) communication (materials and methods); and (4) response centres and personnel. There exists a need for institutionalization of processes for learning from experiences obtained from disasters.Discussion:Action plans presented include: (1) creation of an information and data clearinghouse on disaster management, (2) identification of incentives and disincentives for readiness and develop strategies and interventions, and (3) action on lessons learned from evidence-based research and practical experience.Conclusions:There is an urgent need to proactively establish coordination and management procedures in advance of any crisis. A number of important insights for improvement in coordination and management during disasters emerged.
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Affiliation(s)
- A A Aziz
- [U.S.] Centers for Disease Control and Prevention (CDC), Atlanta, Georgia, USA
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Nichols B, Shrestha RP, Horowitz J, Hollot CV, Germain MJ, Gaweda AE, Chait Y. Simplification of an erythropoiesis model for design of anemia management protocols in end stage renal disease. Annu Int Conf IEEE Eng Med Biol Soc 2012; 2011:83-6. [PMID: 22254256 DOI: 10.1109/iembs.2011.6089902] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
Many end stage renal disease (ESRD) patients suffer from anemia due to insufficient endogenous production of erythropoietin (EPO). The discovery of recombinant human EPO (rHuEPO) over 30 years ago has shifted the treatment of anemia for patients on dialysis from blood transfusions to rHuEPO therapy. Many anemia management protocols (AMPs) used by clinicians comprise a set of experience-based rules for weekly-to-monthly titration of rHuEPO doses based on hemoglobin (Hgb) measurements. In order to facilitate the design of an AMP based on formal control design methods, we present a physiologically-relevant erythropoiesis model, and show that its nonlinear dynamics can be approximated using a static nonlinearity, a step that greatly simplifies AMP design. We demonstrate applicability of our results using clinical data.
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Affiliation(s)
- B Nichols
- Departments, UMass, Amherst, MA 01003, USA
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Shrestha RP, Hollot CV, Chipkin SR, Schmitt CP, Chait Y. A mathematical model of parathyroid hormone response to acute changes in plasma ionized calcium concentration in humans. Math Biosci 2010; 226:46-57. [DOI: 10.1016/j.mbs.2010.04.001] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/24/2009] [Revised: 04/06/2010] [Accepted: 04/12/2010] [Indexed: 10/19/2022]
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Oesterhelt C, Vogelbein S, Shrestha RP, Stanke M, Weber APM. The genome of the thermoacidophilic red microalga Galdieria sulphuraria encodes a small family of secreted class III peroxidases that might be involved in cell wall modification. Planta 2008; 227:353-62. [PMID: 17899175 DOI: 10.1007/s00425-007-0622-z] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/21/2007] [Accepted: 08/27/2007] [Indexed: 05/17/2023]
Abstract
We report the identification of a small family of secreted class III plant peroxidases (Prx) from the genome of the unicellular thermoacidophilic red alga Galdieria sulphuraria (Cyanidiaceae). Apart from two class I ascorbate peroxidases and one cytochrome c peroxidase, the red algal genome encodes four class III plant peroxidases, thus complementing the short list of algal cell wall peroxidases (Passardi et al. in Genomics 89:567-579, 2007). We have characterized the family gene structure, analyzed the extracellular space and cell wall fraction of G. sulphuraria for the presence of peroxidase activity and used shotgun proteomics to identify candidate extracellular peroxidases. For a detailed enzymatic characterization, we have purified a secreted peroxidase (GsPrx04) from the cell-free medium using hydrophobic interaction chromatography. The enzyme proved heat and acid-stable and exhibited an apparent molecular mass of 40 kDa. Comparative genomics between endolithically growing G. sulphuraria and a close relative, the obligatory aquatic, cell wall-less Cyanidioschyzon merolae, revealed that class III peroxidases only occur in the terrestrial microalga, thus supporting the key function of these enzymes in the process of land colonization.
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Affiliation(s)
- C Oesterhelt
- Institut für Biochemie und Biologie, Universität Potsdam, Karl-Liebknecht-Str. 24-25, Haus 20, 14476, Potsdam-Golm, Germany.
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Cochi SL, Markowitz LE, Joshi DD, Owens RC, Stenhouse DH, Regmi DN, Shrestha RP, Lacharya I, Manandhar M, Gurubacharya VL. Control of epidemic group A meningococcal meningitis in Nepal. Int J Epidemiol 1987; 16:91-7. [PMID: 3570627 DOI: 10.1093/ije/16.1.91] [Citation(s) in RCA: 41] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023] Open
Abstract
During the first six months of 1983, an epidemic of serogroup A meningococcal meningitis occurred in the Kathmandu valley of Nepal, resulting in 875 cases and 95 deaths. The annual attack rate was 103 cases per 100,000 population, with a peak attack rate occurring in April. Epidemic meningococcal disease had not been recognized previously in Nepal. Early in 1984, a review of hospital-based data on pyogenic meningitis in Kathmandu showed three times as many cases per month compared with the same period the previous year, suggesting that a recurrent epidemic was unfolding. Beginning in February 1984, a vaccination campaign directed at a high-risk target population of people aged 1-24 years was launched; over 329,000 doses of bivalent A/C meningococcal vaccine were given, achieving approximately 64% coverage of the target population. A dramatic decline in the number of new meningitis cases occurred coincident with the initiation of the mass vaccination campaign. This experience demonstrates that it is possible, with appropriate surveillance efforts, to detect an evolving epidemic of meningococcal disease early in its course and to institute control measures in advance of the expected epidemic peak.
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