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Yang WP, Li MQ, Ding J, Li JY, Wu G, Liu B, Gao YQ, Wang GH, Luo QQ. High-altitude hypoxia exposure inhibits erythrophagocytosis by inducing macrophage ferroptosis in the spleen. eLife 2024; 12:RP87496. [PMID: 38629942 PMCID: PMC11023697 DOI: 10.7554/elife.87496] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/19/2024] Open
Abstract
High-altitude polycythemia (HAPC) affects individuals living at high altitudes, characterized by increased red blood cells (RBCs) production in response to hypoxic conditions. The exact mechanisms behind HAPC are not fully understood. We utilized a mouse model exposed to hypobaric hypoxia (HH), replicating the environmental conditions experienced at 6000 m above sea level, coupled with in vitro analysis of primary splenic macrophages under 1% O2 to investigate these mechanisms. Our findings indicate that HH significantly boosts erythropoiesis, leading to erythrocytosis and splenic changes, including initial contraction to splenomegaly over 14 days. A notable decrease in red pulp macrophages (RPMs) in the spleen, essential for RBCs processing, was observed, correlating with increased iron release and signs of ferroptosis. Prolonged exposure to hypoxia further exacerbated these effects, mirrored in human peripheral blood mononuclear cells. Single-cell sequencing showed a marked reduction in macrophage populations, affecting the spleen's ability to clear RBCs and contributing to splenomegaly. Our findings suggest splenic ferroptosis contributes to decreased RPMs, affecting erythrophagocytosis and potentially fostering continuous RBCs production in HAPC. These insights could guide the development of targeted therapies for HAPC, emphasizing the importance of splenic macrophages in disease pathology.
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Affiliation(s)
- Wan-ping Yang
- Department of Physiology and Hypoxic Biomedicine, Institute of Special Environmental Medicine and Co-innovation Center of Neuroregeneration, Nantong UniversityNantongChina
| | - Mei-qi Li
- Department of Physiology and Hypoxic Biomedicine, Institute of Special Environmental Medicine and Co-innovation Center of Neuroregeneration, Nantong UniversityNantongChina
| | - Jie Ding
- Department of Physiology and Hypoxic Biomedicine, Institute of Special Environmental Medicine and Co-innovation Center of Neuroregeneration, Nantong UniversityNantongChina
| | - Jia-yan Li
- Department of Physiology and Hypoxic Biomedicine, Institute of Special Environmental Medicine and Co-innovation Center of Neuroregeneration, Nantong UniversityNantongChina
| | - Gang Wu
- College of High-Altitude Military Medicine, Institute of Medicine and Hygienic Equipment for High Altitude Region, Army Medical UniversityChongqingChina
- Key Laboratory of Extreme Environmental Medicine and High-Altitude Medicine, Ministry of Education of ChinaChongqingChina
| | - Bao Liu
- College of High-Altitude Military Medicine, Institute of Medicine and Hygienic Equipment for High Altitude Region, Army Medical UniversityChongqingChina
- Key Laboratory of Extreme Environmental Medicine and High-Altitude Medicine, Ministry of Education of ChinaChongqingChina
| | - Yu-qi Gao
- College of High-Altitude Military Medicine, Institute of Medicine and Hygienic Equipment for High Altitude Region, Army Medical UniversityChongqingChina
- Key Laboratory of Extreme Environmental Medicine and High-Altitude Medicine, Ministry of Education of ChinaChongqingChina
| | - Guo-hua Wang
- Department of Physiology and Hypoxic Biomedicine, Institute of Special Environmental Medicine and Co-innovation Center of Neuroregeneration, Nantong UniversityNantongChina
- Department of Neurosurgery, Southwest Hospital, Army Medical UniversityChongqingChina
| | - Qian-qian Luo
- Department of Physiology and Hypoxic Biomedicine, Institute of Special Environmental Medicine and Co-innovation Center of Neuroregeneration, Nantong UniversityNantongChina
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Hsia CCW. Tissue Perfusion and Diffusion and Cellular Respiration: Transport and Utilization of Oxygen. Semin Respir Crit Care Med 2023; 44:594-611. [PMID: 37541315 DOI: 10.1055/s-0043-1770061] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 08/06/2023]
Abstract
This article provides an overview of the journey of inspired oxygen after its uptake across the alveolar-capillary interface, and the interplay among tissue perfusion, diffusion, and cellular respiration in the transport and utilization of oxygen. The critical interactions between oxygen and its facilitative carriers (hemoglobin in red blood cells and myoglobin in muscle cells), and with other respiratory and vasoactive molecules (carbon dioxide, nitric oxide, and carbon monoxide), are emphasized to illustrate how this versatile system dynamically optimizes regional convective transport and diffusive gas exchange. The rates of reciprocal gas exchange in the lung and the periphery must be well-matched and sufficient for meeting the range of energy demands from rest to maximal stress but not excessive as to become toxic. The mobile red blood cells play a vital role in matching tissue perfusion and gas exchange by dynamically regulating the controlled uptake of oxygen and communicating regional metabolic signals across different organs. Intracellular oxygen diffusion and facilitation via myoglobin into the mitochondria, and utilization via electron transport chain and oxidative phosphorylation, are summarized. Physiological and pathophysiological adaptations are briefly described. Dysfunction of any component across this integrated system affects all other components and elicits corresponding structural and functional adaptation aimed at matching the capacities across the entire system and restoring equilibrium under normal and pathological conditions.
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Affiliation(s)
- Connie C W Hsia
- Division of Pulmonary and Critical Care Medicine, Department of Internal Medicine, University of Texas Southwestern Medical Center, Dallas, Texas
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Siemon H. Use of a Bipolar Vessel-Sealing Device for Splenic Parenchymal Resection in Three Dogs and One Cat. J Am Anim Hosp Assoc 2021; 57:32-36. [PMID: 33260205 DOI: 10.5326/jaaha-ms-6927] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 01/30/2020] [Indexed: 11/11/2022]
Abstract
Based on splenic abnormalities noted during surgery, four client-owned animals (three dogs, one cat) undergoing exploratory laparotomy were identified as candidates for partial splenectomy. In three cases, small mass lesions of the spleen were identified on elective exploratory laparotomy. In one case, the patient was referred for emergency surgery for diaphragmatic hernia with entrapment of stomach and spleen. The discovery of avulsion of a significant portion of the splenic mesentery led to the decision to perform partial splenectomy in this case. All animals included in the study underwent partial splenectomy by one of two board-certified veterinary surgeons at a multispecialty hospital between 2014 and 2018. The same type of bipolar vessel-sealing device was used in each surgery, and three of four partial splenectomy cases recovered uneventfully. One patient went into cardiopulmonary arrest hours after surgery and died; however, this is not suspected to be due to the described partial splenectomy technique. The bipolar vessel-sealing device is suitable for use in resection of the splenic parenchyma in some canine and feline patients. This technique is designed to decrease surgical time, provide effective hemostasis, and preserve the important functions of the spleen that are lost when total splenectomy is undertaken.
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Affiliation(s)
- Heather Siemon
- From BluePearl Veterinary Partners San Antonio, San Antonio, Texas
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4
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Nowak S, Szewczyk M, Tomczak P, Całus I, Figura M, Mysłajek RW. Social and environmental factors influencing contemporary cases of wolf aggression towards people in Poland. EUR J WILDLIFE RES 2021. [DOI: 10.1007/s10344-020-01455-1] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
AbstractUnderstanding factors and mechanisms causing large carnivore aggression towards people is crucial for their conservation in modern human-dominated landscapes. We present detailed descriptions of wolf attacks on people in early summer 2018 in two areas of Poland, analysis of behaviour, fitness and origin of individuals responsible for the attacks and management actions undertaken by local communities as well as governmental bodies and non-governmental organisations. We show that attacks were caused by yearling wolves (13-month-old male and 14-month-old female) originating from local packs, which appeared near households several months prior to incidents. Both individuals were positively food-conditioned and showed increasing habituation caused by irresponsible behaviour of people such as long-lasting intentional feeding or illegal keeping. Post mortem necropsy revealed obesity and serious abnormality of spleen (polysplenia) in the problem female wolf that negatively impacted her fitness and was the most likely reason for her presence near households and feeding on leftovers. Despite prolonged observations of these wolves very close to human settlements (less than 30 m), no mitigation actions were undertaken until the attacks, after which both individuals were killed. We provide several recommendations to avoid aggressive human-carnivore encounters.
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Lodin-Sundström A, Holmström P, Ekstam M, Söderberg D, Schagatay E. Splenic contraction is enhanced by exercise at simulated high altitude. Eur J Appl Physiol 2021; 121:1725-1732. [PMID: 33683439 PMCID: PMC8144132 DOI: 10.1007/s00421-021-04637-0] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/02/2020] [Accepted: 02/09/2021] [Indexed: 11/30/2022]
Abstract
Purpose Splenic contraction increases circulating hemoglobin (Hb) with advantages during hypoxia. As both hypoxia and exercise have been shown to be important separate triggers of splenic contraction we aimed to investigate if the spleen response to simulated high altitude (HA) is enhanced by superimposing exercise. Method Fourteen healthy volunteers (seven females) performed the following protocol in a normobaric environment sitting on an ergometer cycle: 20 min rest in normoxia; 20 min rest while breathing hypoxic gas simulating an altitude of 3500 m; 10 min exercise at an individually set intensity while breathing the hypoxic gas; 20 min rest in hypoxia; and finally 20 min rest in normoxia. Spleen measurements were collected by ultrasonic imaging and venous Hb measured at the end of each intervention. Result Mean ± SD baseline spleen volume during normoxic rest was 280 ± 107 mL, the volume was reduced by 22% during rest in hypoxia to 217 ± 92 mL (p < 0.001) and by 33% during exercise in hypoxia (189 mL; p < 0.001). Hb was 140.7 ± 7.0 g/L during normoxic rest and 141.3 ± 7.4 g/L during hypoxic rest (NS), but increased by 5.3% during hypoxic exercise (148.6 ± 6.3 g/L; p < 0.001). Spleen volume and Hb were stepwise changed back to baseline at cessation of exercise and return to normoxia. Conclusion Splenic contraction is induced by hypoxia and further enhanced by superimposing exercise, and reduced when exercise ceases, in a step-wise manner, showing that the tonic but partial contraction observed in long-term field expeditions to HA may occur also in the short term. This “graded response” may be beneficial during acclimatization to HA, to cope with moderate chronic hypoxia during rest while allowing additional enhancement of oxygen carrying capacity to overcome short bouts of extreme hypoxia caused by exercise.
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Affiliation(s)
- Angelica Lodin-Sundström
- Department of Health Sciences, Mid Sweden University, Östersund, Sweden. .,Environmental Physiology Group, Department of Nursing Science, Mid Sweden University, Holmgatan 10, 85170, Sundsvall, Sweden.
| | - Pontus Holmström
- Department of Health Sciences, Mid Sweden University, Östersund, Sweden
| | - Marcus Ekstam
- Department of Health Sciences, Mid Sweden University, Östersund, Sweden
| | - Daniel Söderberg
- Department of Health Sciences, Mid Sweden University, Östersund, Sweden
| | - Erika Schagatay
- Department of Health Sciences, Mid Sweden University, Östersund, Sweden.,Swedish Winter Sports Research Centre, Östersund, Sweden
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Abstract
Population genomic studies of humans and other animals at high altitude have generated many hypotheses about the genes and pathways that may have contributed to hypoxia adaptation. Future advances require experimental tests of such hypotheses to identify causal mechanisms. Studies to date illustrate the challenge of moving from lists of candidate genes to the identification of phenotypic targets of selection, as it can be difficult to determine whether observed genotype-phenotype associations reflect causal effects or secondary consequences of changes in other traits that are linked via homeostatic regulation. Recent work on high-altitude models such as deer mice has revealed both plastic and evolved changes in respiratory, cardiovascular, and metabolic traits that contribute to aerobic performance capacity in hypoxia, and analyses of tissue-specific transcriptomes have identified changes in regulatory networks that mediate adaptive changes in physiological phenotype. Here we synthesize recent results and discuss lessons learned from studies of high-altitude adaptation that lie at the intersection of genomics and physiology.
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Affiliation(s)
- Jay F Storz
- School of Biological Sciences, University of Nebraska, Lincoln, Nebraska 68588, USA;
| | - Zachary A Cheviron
- Division of Biological Sciences, University of Montana, Missoula, Montana 59812, USA;
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7
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Hanadhita D, Rahma A, Prawira AY, Mayasari NLPI, Satyaningtijas AS, Hondo E, Agungpriyono S. The spleen morphophysiology of fruit bats. Anat Histol Embryol 2019; 48:315-324. [PMID: 30968443 PMCID: PMC7159459 DOI: 10.1111/ahe.12442] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/13/2018] [Revised: 02/12/2019] [Accepted: 03/16/2019] [Indexed: 11/29/2022]
Abstract
Spleen is one of the important lymphoid organs with wide variations of morphological and physiological functions according to species. Morphology and function of the spleen in bats, which are hosts to several viral strains without exhibiting clinical symptoms, remain to be fully elucidated. This study aims to examine the spleen morphology of fruit bats associated with their physiological functions. Spleen histological observations were performed in three fruit bats species: Cynopterus titthaecheilus (n = 9), Rousettus leschenaultii (n = 3) and Pteropus vampyrus (n = 3). The spleens of these fruit bats were surrounded by a thin capsule. Red pulp consisted of splenic cord and wide vascular space filled with blood. Ellipsoids in all three studied species were found numerously and adjacent to one another forming macrophages aggregates. White pulp consisted of periarteriolar lymphoid sheaths (PALS), lymphoid follicles and marginal zone. The lymphoid follicle contained a germinal centre and a tingible body macrophage that might reflect an active immune system. The marginal zone was prominent and well developed. This study reports some differences in spleen structure of fruit bats compared to other bat species previously reported and discusses possible physiological implications of the spleen based on its morphology.
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Affiliation(s)
- Desrayni Hanadhita
- Department of Anatomy Physiology and Pharmacology, Faculty of Veterinary MedicineBogor Agricultural University (IPB)BogorIndonesia
| | - Anisa Rahma
- Department of Anatomy Physiology and Pharmacology, Faculty of Veterinary MedicineBogor Agricultural University (IPB)BogorIndonesia
| | - Andhika Yudha Prawira
- Department of Anatomy Physiology and Pharmacology, Faculty of Veterinary MedicineBogor Agricultural University (IPB)BogorIndonesia
| | - Ni Luh Putu Ika Mayasari
- Department of Animal Disease and Veterinary Public Health, Faculty of Veterinary MedicineBogor Agricultural University (IPB)BogorIndonesia
| | - Aryani Sismin Satyaningtijas
- Department of Anatomy Physiology and Pharmacology, Faculty of Veterinary MedicineBogor Agricultural University (IPB)BogorIndonesia
| | - Eiichi Hondo
- Laboratory of Animal Morphology, Graduate School of Bioagricultural SciencesNagoya UniversityNagoyaJapan
| | - Srihadi Agungpriyono
- Department of Anatomy Physiology and Pharmacology, Faculty of Veterinary MedicineBogor Agricultural University (IPB)BogorIndonesia
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Lee M, Park J, Choi H, Lee H, Jeong SM. Presurgical assessment of splenic tumors in dogs: a retrospective study of 57 cases (2012-2017). J Vet Sci 2019; 19:827-834. [PMID: 30173499 PMCID: PMC6265589 DOI: 10.4142/jvs.2018.19.6.827] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2018] [Revised: 08/12/2018] [Accepted: 08/15/2018] [Indexed: 01/06/2023] Open
Abstract
The purpose of this study was to evaluate the clinical and imaging characteristics of canine splenic tumors and to establish guidelines for the presurgical assessment of splenic tumors in dogs. Fifty-seven dogs that underwent total splenectomy for the treatment of splenic tumors were evaluated by examining medical records, hematologic results, diagnostic imaging results, and histopathologic results. The maximum lesion size from ultrasonography was significantly different between malignant and benign tumors (p = 0.002). There was a correlation between tumor margination and type of splenic tumors (p = 0.045). Precontrast lesion attenuation on computed tomography was significantly different between splenic malignant and benign tumors (p = 0.001). The mean ± SD precontrast lesion attenuation of malignant tumors was 40.3 ± 5.9 Hounsfield units (HU), and for benign tumors, it was 52.8 ± 6.8 HU. In conclusion, some variables of the imaging examination could be used to distinguish the type of splenic tumor. Based on the study results, using a diagnostic flowchart would be effective in increasing the survival rate of patients with splenic malignant tumors. In addition, fine needle aspiration or magnetic resonance imaging prior to surgical exploration and histopathologic examination may be useful in achieving a more accurate diagnosis.
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Affiliation(s)
- Mokhyeon Lee
- Department of Veterinary Surgery, College of Veterinary Medicine, Chungnam National University, Daejeon 34134, Korea
| | - Jiyoung Park
- Department of Veterinary Surgery, College of Veterinary Medicine, Chungnam National University, Daejeon 34134, Korea
| | - Hojung Choi
- Department of Veterinary Diagnostic Imaging, College of Veterinary Medicine, Chungnam National University, Daejeon 34134, Korea
| | - Haebeom Lee
- Department of Veterinary Surgery, College of Veterinary Medicine, Chungnam National University, Daejeon 34134, Korea
| | - Seong Mok Jeong
- Department of Veterinary Surgery, College of Veterinary Medicine, Chungnam National University, Daejeon 34134, Korea
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9
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Abstract
Structural and functional complexities of the mammalian lung evolved to meet a unique set of challenges, namely, the provision of efficient delivery of inspired air to all lung units within a confined thoracic space, to build a large gas exchange surface associated with minimal barrier thickness and a microvascular network to accommodate the entire right ventricular cardiac output while withstanding cyclic mechanical stresses that increase several folds from rest to exercise. Intricate regulatory mechanisms at every level ensure that the dynamic capacities of ventilation, perfusion, diffusion, and chemical binding to hemoglobin are commensurate with usual metabolic demands and periodic extreme needs for activity and survival. This article reviews the structural design of mammalian and human lung, its functional challenges, limitations, and potential for adaptation. We discuss (i) the evolutionary origin of alveolar lungs and its advantages and compromises, (ii) structural determinants of alveolar gas exchange, including architecture of conducting bronchovascular trees that converge in gas exchange units, (iii) the challenges of matching ventilation, perfusion, and diffusion and tissue-erythrocyte and thoracopulmonary interactions. The notion of erythrocytes as an integral component of the gas exchanger is emphasized. We further discuss the signals, sources, and limits of structural plasticity of the lung in alveolar hypoxia and following a loss of lung units, and the promise and caveats of interventions aimed at augmenting endogenous adaptive responses. Our objective is to understand how individual components are matched at multiple levels to optimize organ function in the face of physiological demands or pathological constraints.
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Affiliation(s)
- Connie C.W. Hsia
- Department of Internal Medicine, University of Texas Southwestern Medical Center, Dallas, Texas, USA
| | - Dallas M. Hyde
- California National Primate Research Center, University of California at Davis, Davis, California, USA
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10
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Abstract
The human spleen shows a decrease in volume of around 40% early during vigorous exercise and in response to other stressful stimuli such as maximal apnoea and the breathing of hypoxic gas mixtures. Contraction seems an active response, mediated by alpha-adrenergic fibres in the splenic nerve. Given the relatively small size of the human spleen, the effect upon physical performance is likely to be small; the augmentation of total blood volume is <2%, and even taking account of other causes of haemoconcentration during vigorous exercise, the increase of haematocrit is <10%. However, one of two studies suggested that the haemoconcentration may be sufficient to cause errors in the traditional method for calculating exercise-induced changes of plasma volume. The spleen also contributes leucocytes and platelets to the general circulation as part of the "fight or flight" reaction to stressors. The mobilisation of leucocytes proceeds more slowly than that of the red cells; it depends not only upon an active contraction of the spleen, but also a modulation of leucocyte adhesion molecules. Splenectomy impairs exercise performance in horses, but human performance data are lacking; overall health effects seem minimal, and many patients live many years after removal of their spleens.
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Affiliation(s)
- Roy J Shephard
- a Faculty of Kinesiology & Physical Education , University of Toronto , Toronto , Canada
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11
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Persistent structural adaptation in the lungs of guinea pigs raised at high altitude. Respir Physiol Neurobiol 2014; 208:37-44. [PMID: 25534146 DOI: 10.1016/j.resp.2014.12.011] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/21/2014] [Revised: 11/18/2014] [Accepted: 12/15/2014] [Indexed: 11/20/2022]
Abstract
Laboratory guinea pigs raised at high altitude (HA, 3800 m) for up to 6 mo exhibit enhanced alveolar growth and remodeling (Hsia et al., 2005. Resp. Physiol. Neurobiol. 147, 105-115). To determine whether initial HA-induced structural enhancement persists following return to intermediate altitude (IA), we raised weanling guinea pigs at (a) HA for 11-12 mo, (b) IA (1200 m) for 11-12 mo, and (c) HA for 4 mo followed by IA for 7-8 mo (HA-to-IA). Morphometric analysis was performed under light and electron microscopy. Body weight and lung volume were similar among groups. Prolonged HA residence increased alveolar epithelium and interstitium volumes while reducing alveolar-capillary blood volume. The HA-induced gains in type-1 epithelium volume and alveolar surface area were no longer present following return to IA whereas volume increases in type-2 epithelium and interstitium and the reduction in alveolar duct volume persisted. Results demonstrate persistent augmentation of some but not all aspects of lung structure throughout prolonged HA residence, with partial reversibility following re-acclimatization to IA.
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12
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Liu SY, Chang CH, Lee TW. Single dose acute toxicity testing for N,N-bis(2-mercaptoethyl)-N',N' diethylethylenediamine in beagles. Regul Toxicol Pharmacol 2014; 69:217-25. [PMID: 24721389 DOI: 10.1016/j.yrtph.2014.04.001] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/11/2013] [Revised: 03/29/2014] [Accepted: 04/01/2014] [Indexed: 10/25/2022]
Abstract
N,N-Bis(2-mercaptoethyl)-N',N'-diethylenediamine (BMEDA) is used in the preparation of the (188)Re-BMEDA-liposome as a chelator to deliver rhenium 188 into liposomes. Although the safety of the (188)Re-BMEDA-liposome had been established, the use of BMEDA in preparing the liposome is of interest; however, an assessment of its safety is warranted. In this present work, we report on the acute toxicity study of BMEDA in beagles to identify doses causing no adverse effect and doses causing life-threatening toxicity. In a single dose 14-day systemic toxicity study conducted in beagles, BMEDA was without compound-related adverse effects at doses of up to 2mg/kg in a series of clinical observations and clinical pathology examinations. The results of these studies could aid in choosing doses for repeat-dose studies and in the selection of starting doses for Phase 1 human studies.
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Affiliation(s)
- Si-Yen Liu
- Isotope Application Division, Institute of Nuclear Energy Research, Taoyuan, Taiwan
| | - Chih-Hsien Chang
- Isotope Application Division, Institute of Nuclear Energy Research, Taoyuan, Taiwan
| | - Te-Wei Lee
- Isotope Application Division, Institute of Nuclear Energy Research, Taoyuan, Taiwan.
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13
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Yilmaz C, Ravikumar P, Bellotto DJ, Unger RH, Hsia CCW. Fatty diabetic lung: functional impairment in a model of metabolic syndrome. J Appl Physiol (1985) 2010; 109:1913-9. [PMID: 20798271 DOI: 10.1152/japplphysiol.00549.2010] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
The Zucker diabetic fatty (ZDF fa/fa) rat with genetic leptin insensitivity develops obesity and Type 2 diabetes mellitus (T2DM) with age accompanied by hyperplastic changes in the distal lung (Am J Physiol Lung Cell Mol Physiol 298: L392-L403, 2010). To determine the functional consequences of structural changes, we developed a rebreathing (RB) technique to simultaneously measure lung volume, pulmonary blood flow, lung diffusing capacity (Dl(CO)), membrane diffusing capacity (Dm(CO)), pulmonary capillary blood volume (Vc), and septal tissue volume in anesthetized tracheostomized male ZDF fa/fa and matched lean (+/+) control animals at 4, 8, and 12 mo of age. Results obtained by RB technique were compared with that measured by a single-breath (SB) technique and to that expected in a wide range of species. In fa/fa animals compared with +/+, lung volumes and compliance were 13-35% lower at different ages, and the normal age-related increase in lung compliance was no longer evident. Mean pulmonary blood flow declined with age in fa/fa but not in +/+ animals. Dl(CO) measured at a given pulmonary blood flow was 20-43% lower at different ages due to reductions in both Dm(CO) and Vc. Septal tissue volume was also reduced in older fa/fa rats. We conclude that obese rats with T2DM develop significant restrictive pulmonary defects with diffusion impairment in a pattern similar to that previously reported in obese human subjects with T2DM. Functional impairment became exaggerated with age and duration of T2DM. In both fa/fa and +/+ animals, Dl(CO) measured by RB was systematically higher than by SB technique whereas lung volume was similar, a finding consistent with heterogeneous distribution of ventilation in the rat lung.
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Affiliation(s)
- Cuneyt Yilmaz
- Department of Internal Medicine, Pulmonary and Critical Care Medicine, University of Texas Southwestern Medical Center, 5323 Harry Hines Blvd., Dallas, TX 75390-9034, USA
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Optimal hematocrit for maximal exercise performance in acute and chronic erythropoietin-treated mice. Proc Natl Acad Sci U S A 2009; 107:419-23. [PMID: 19966291 DOI: 10.1073/pnas.0912924107] [Citation(s) in RCA: 81] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Erythropoietin (Epo) treatment increases hematocrit (Htc) and, consequently, arterial O(2) content. This in turn improves exercise performance. However, because elevated blood viscosity associated with increasing Htc levels may limit cardiac performance, it was suggested that the highest attainable Htc may not necessarily be associated with the highest attainable exercise capacity. To test the proposed hypothesis that an optimal Htc in acute and chronic Epo-treated mice exists--i.e., the Htc that facilitates the greatest O(2) flux during maximal exercise--Htc levels of wild-type mice were acutely elevated by administering novel erythropoiesis-stimulating protein (NESP; wtNESP). Furthermore, in the transgenic mouse line tg6 that reaches Htc levels of up to 0.9 because of constitutive overexpression of human Epo, the Htc was gradually reduced by application of the hemolysis-inducing compound phenylhydrazine (PHZ; tg6PHZ). Maximal cardiovascular performance was measured by using telemetry in all exercising mice. Highest maximal O(2) uptake (VO(2max)) and maximal time to exhaustion at submaximal exercise intensities were reached at Htc values of 0.58 and 0.57 for wtNESP, and 0.68 and 0.66 for tg6PHZ, respectively. Rate pressure product, and thus also maximal working capacity of the heart, increased with elevated Htc values. Blood viscosity correlated with VO(2max). Apart from the confirmation of the Htc hypothesis, we conclude that tg6PHZ adapted better to varying Htc values than wtNESP because of the higher optimal Htc of tg6PHZ compared to wtNESP. Of note, blood viscosity plays a critical role in limiting exercise capacity.
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15
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Hsia CCW, Wagner PD, Dane DM, Wagner HE, Johnson RL. Predicting diffusive alveolar oxygen transfer from carbon monoxide-diffusing capacity in exercising foxhounds. J Appl Physiol (1985) 2008; 105:1441-7. [PMID: 18719238 PMCID: PMC2584845 DOI: 10.1152/japplphysiol.01328.2007] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2007] [Accepted: 08/18/2008] [Indexed: 11/22/2022] Open
Abstract
Although lung diffusing capacity for carbon monoxide (DL(CO)) is a widely used test of diffusive O2 transfer, few studies have directly related DL(CO) to O2-diffusing capacity (DL(O2)); none has used the components of Dl(CO), i.e., conductance of alveolar membrane and capillary blood, to predict DL(O2) from rest to exercise. To understand the relationship between DL(CO) and DL(O2) at matched levels of cardiac output, we analyzed cumulative data from rest to heavy exercise in 43 adult dogs, with normal lungs or reduced lung capacity following lung resection, that were studied by two techniques. 1) A rebreathing (RB) technique was used to measure Dl(CO) and pulmonary blood flow at two O2 tensions, independent of O2 exchange. DL(CO) was partitioned into CO-diffusing capacity of alveolar membrane and pulmonary capillary blood volume using the Roughton-Forster equation and converted into an equivalent DL(O2), [DL(O2)(RB)]. 2) A multiple inert-gas elimination technique (MIGET) was used to measure ventilation-perfusion distributions, O2 and CO2 exchange under hypoxia, to derive DL(O2) [DL(O2)(MIGET)] by the Lilienthal-Riley technique and Bohr integration. For direct comparisons, DL(O2)(RB) was interpolated to the cardiac output measured by the Fick principle corresponding to DL(O2)(MIGET). The DL(O2)-to-DL(CO) ratio averaged 1.61. Correlation between DL(O2)(RB) and DL(O2)(MIGET) was similar in normal and post-resection groups. Overall, DL(O2)(MIGET) = 0.975 DL(O2)(RB); mean difference between the two techniques was under 5% for both animal groups. We conclude that, despite various uncertainties inherent in these two disparate methods, the Roughton-Forster equation adequately predicts diffusive O2 transfer from rest to heavy exercise in canines with normal, as well as reduced, lung capacities.
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Affiliation(s)
- Connie C W Hsia
- Department of Internal Medicine, Pulmonary and Critical Care Medicine, University of Texas Southwestern Medical Center, 5323 Harry Hines Blvd., Dallas, TX 75390-9034, USA
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Frances MF, Dujic Z, Shoemaker JK. Splenic constriction during isometric handgrip exercise in humans. Appl Physiol Nutr Metab 2008; 33:990-6. [DOI: 10.1139/h08-087] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
During the first minute of a moderate-intensity isometric handgrip (HG) exercise, there is an increase in stroke volume and cardiac output that occurs without any change in systemic vascular conductance. Although the mechanism of increased venous return is not yet known, current focus has been placed on the constriction of visceral organs. The human spleen represents a compliant organ with high perfusion that constricts during the rather severe stresses of maximal exercise, a diving reflex, or prolonged apnea. This study tested the hypothesis that spleen constriction occurs during isometric HG exercise. Eight participants performed a 1 min isometric HG test at 40% maximum voluntary contraction. Splenic length and width were measured (with ultrasound imaging) after 1 min of exercise, and volume was calculated. To investigate the reflex specificity of this response, spleen dimensions were also measured during 4 min of lower-body negative pressure (LBNP; –20 mm Hg). To test the additional impact of altered breathing and intra-abdominal pressures during the HG, measures were also taken during Valsalva’s manoeuvre (VM) at 30 mm Hg. Compared with baseline, both length and width of the spleen were reduced by 0.20 to 0.55 cm (or 4.44%–6.09%; p < 0.05) during each test. This resulted in relative reductions in splenic volume of 13 ± 1% (HG), 9% ± 7% (LBNP) and 18% ± 7% (VM) (p < 0.05; all mean ± SD). It was concluded that the spleen can constrict during the first minute of isometric HG exercise.
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Affiliation(s)
- Maria F. Frances
- School of Kinesiology, the University of Western Ontario, London, ON N6A 3K7, Canada
- Department of Physiology, University of Split School of Medicine, Split, Croatia
- Department of Physiology and Pharmacology, the University of Western Ontario, London, ON N6A 3K7, Canada
| | - Zeljko Dujic
- School of Kinesiology, the University of Western Ontario, London, ON N6A 3K7, Canada
- Department of Physiology, University of Split School of Medicine, Split, Croatia
- Department of Physiology and Pharmacology, the University of Western Ontario, London, ON N6A 3K7, Canada
| | - J. Kevin Shoemaker
- School of Kinesiology, the University of Western Ontario, London, ON N6A 3K7, Canada
- Department of Physiology, University of Split School of Medicine, Split, Croatia
- Department of Physiology and Pharmacology, the University of Western Ontario, London, ON N6A 3K7, Canada
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Abstract
Abstractl-Carnitine supplementation can stimulate erythropoiesis, reduce exercise-induced plasma lactate concentrations and decrease post-exercise muscle damage. Next to horses, Greyhounds represent the premier animal racing species and perform short-duration, very high-intensity exercise that has the potential to incur substantial muscle damage. Under resting and standard racing conditions (5/16 mile), we tested the novel hypotheses that l-carnitine supplementation in Greyhounds would: (1) elevate haematocrit at rest and immediately post-exercise; (2) reduce peak post-exercise plasma lactate; and (3) reduce indices of muscle damage (plasma creatine phosphokinase, CPK and aspartate aminotransferase, AST). Six conditioned Greyhounds (30.1 ± 1.6 kg) underwent a randomized placebo-controlled crossover study to determine the effects of 6 weeks of l-carnitine supplementation (100 mg kg− 1 of body weight/day) at rest and following a maximal speed 5/16 mile race. In accordance with our hypotheses, l-carnitine elevated resting and immediately post-race haematocrit (control, 60.1 ± 1.7, l-carnitine, 63.6 ± 1.7; P < 0.05) and reduced peak post-race plasma CPK and AST concentrations (both P < 0.05). Those dogs with the highest peak post-exercise plasma CPK concentrations under placebo conditions evidenced the greatest reduction with l-carnitine supplementation (r = 0.99, P < 0.01). However, contrary to our hypotheses, l-carnitine did not change peak post-exercise plasma lactate concentrations (control, 27.0 ± 2.1, l-carnitine, 27.7 ± 1.3; P>0.05). We conclude that l-carnitine supplementation increases the potential for oxygen transport and reduces plasma indicators of muscle damage, CPK and AST in racing Greyhounds.
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Hsia CCW, Johnson RL, Dane DM, Wu EY, Estrera AS, Wagner HE, Wagner PD. The canine spleen in oxygen transport: gas exchange and hemodynamic responses to splenectomy. J Appl Physiol (1985) 2007; 103:1496-505. [PMID: 17673565 DOI: 10.1152/japplphysiol.00281.2007] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
In athletic animals the spleen induces acute polycythemia by dynamic contraction that releases red blood cells into the circulation in response to increased O(2) demand and metabolic stress; when energy demand is relieved, the polycythemia is rapidly reversed by splenic relaxation. We have shown in adult foxhounds that splenectomy eliminates exercise-induced polycythemia, thereby reducing peak O(2) uptake and lung diffusing capacity for carbon monoxide (DL(CO)) as well as exaggerating preexisting DL(CO) impairment imposed by pneumonectomy (Dane DM, Hsia CC, Wu EY, Hogg RT, Hogg DC, Estrera AS, Johnson RL Jr. J Appl Physiol 101: 289-297, 2006). To examine whether the postsplenectomy reduction in DL(CO) leads to abnormalities in O(2) diffusion, ventilation-perfusion inequality, or hemodynamic function, we studied these animals via the multiple inert gas elimination technique at rest and during exercise at a constant workload equivalent to 50% or 80% of peak O(2) uptake while breathing 21% and 14% O(2) in balanced order. From rest to exercise after splenectomy, minute ventilation was significantly elevated with respect to O(2) uptake compared with exercise before splenectomy; cardiac output, O(2) delivery, and mean pulmonary and systemic arterial blood pressures were 10-20% lower, while O(2) extraction was elevated with respect to O(2) uptake. Ventilation-perfusion inequality was unchanged, but O(2) diffusing capacities of lung (DL(O2)) and peripheral tissue during exercise were lower with respect to cardiac output postsplenectomy by 32% and 25%, respectively. The relationship between DL(O2) and DL(CO) was unchanged by splenectomy. We conclude that the canine spleen regulates both convective and diffusive O(2) transport during exercise to increase maximal O(2) uptake.
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Affiliation(s)
- Connie C W Hsia
- Dept. of Internal Medicine, Univ. of Texas Southwestern Medical Center, 5323 Harry Hines Blvd., Dallas, TX 75390-9034, USA
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Hsia CCW, Johnson RL, McDonough P, Dane DM, Hurst MD, Fehmel JL, Wagner HE, Wagner PD. Residence at 3,800-m altitude for 5 mo in growing dogs enhances lung diffusing capacity for oxygen that persists at least 2.5 years. J Appl Physiol (1985) 2007; 102:1448-55. [PMID: 17218427 DOI: 10.1152/japplphysiol.00971.2006] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Mammals native to high altitude (HA) exhibit larger lung volumes than their lowland counterparts. To test the hypothesis that adaptation induced by HA residence during somatic maturation improves pulmonary gas exchange in adulthood, male foxhounds born at sea level (SL) were raised at HA (3,800 m) from 2.5 to 7.5 mo of age and then returned to SL prior to somatic maturity while their littermates were simultaneously raised at SL. Following return to SL, all animals were trained to run on a treadmill; gas exchange and hemodynamics were measured 2.5 years later at rest and during exercise while breathing 21% and 13% O(2). The multiple inert gas elimination technique was employed to estimate ventilation-perfusion (Va/Q) distributions and lung diffusing capacity for O(2) (Dl(O(2))). There were no significant intergroup differences during exercise breathing 21% O(2). During exercise breathing 13% O(2), peak O(2) uptake and Va/Q distributions were similar between groups but arterial pH, base excess, and O(2) saturation were higher while peak lactate concentration was lower in animals raised at HA than at SL. At a given exercise intensity, alveolar-arterial O(2) tension gradient (A-aDo(2)) attributable to diffusion limitation was lower while Dlo(2) was 12-25% higher in HA-raised animals. Mean systemic arterial blood pressure was also lower in HA-raised animals; mean pulmonary arterial pressures were similar. We conclude that 5 mo of HA residence during maturation enhances long-term gas exchange efficiency and Dl(O(2)) without impacting Va/Q inequality during hypoxic exercise at SL.
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Affiliation(s)
- Connie C W Hsia
- Department of Internal Medicine, University of Texas Southwestern Medical Center, Dallas, Texas, TX 75390-9034, USA
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