Hypoxia chronic

Ischemic preconditioning is the phenomenon characterized by increased myocardial tolerance to ischemia and reperfusion injury induced by prior brief episodes of 

---

Additionally, with chronic hypoxia, normal hemoglobin and hematocrit values may represent relative anemia.12 Increased red blood cell production is a physiologic response to hypoxia however, this response may be blunted in CF and may result in symptoms of anemia despite normal lab values. Abnormal bleeding may also be observed as a result of vitamin K malabsorption or antibiotic-associated depletion of gastrointestinal flora and vitamin K synthesis. 

Unno, N., Menconi, M.J., Salzman, A.L., Smith, M., Hagen, S., Ge, Y., Ezzell, R.M., Fink, M.P., Hyperpermeability and ATP depletion induced by chronic hypoxia or glycolytic inhibition in Caco-2BBe monolayers. Am J Physiol 270, G1010-G1021 (1996). 

Kobayashi S, Zimmermann H, Millhorn DE (2000) Chronic hypoxia enhances adenosine release in rat PC 12 cells by altering adenosine metabolism and membrane transport. J Neurochem 74(2) 621-632... 

It has been specifically focused on responses to chronic hypoxia that involve adenosine-induced changes in the transcription regulator HIF-1 expression. In particular, it has been investigated the correlation between adenosine receptor stimulation and/or blockade and HIF-la expression modulation in hypoxia. It has been demonstrated that adenosine is able to increase HIF-la protein expression in response to hypoxia in a dose- and time-dependent manner in human melanoma, glioblastoma and tumor colon cells (Merighi et al. 2005,2006,2007). These results indicate that the cell surface A3 adenosine receptor transduces extracellular hypoxic signals into the cell interior. 

Bernstein, D., Doshi, R., Huang, S., Strandness, E., and Jasper, J.R. 1992. Transcriptional regulation of left ventricular p-adrenergic receptors during chronic hypoxia. Circ. Res. 71 1465-1471. 

Le Cras, T.D., Xue, C., Rengasamy, A., and Johns, R.A. 1996. Chronic hypoxia up regulates endothelial and inducible NO synthase gene and protein expression in rat lung. Am. J. Physiol. 270 L164-L170. 

Hochachka, P.W. (1993a). Adaptability of metabolic efficiencies under chronic hypoxia in man. In Surviving Hypoxia, pp. 127-135, ed. P.W. Hochachka, P.L. Lutz, T. Sick, M. Rosenthal, and G. van den Thillart. Boca Raton, Fla. CRC Press. 

Webster, K.A., and N.H. Bishopric (1992). Molecular regulation of cardiac myocyte adaptations to chronic hypoxia. J. Mol. Cell. Cardiol. 24 741-751. 

Hochachka, P.W., C.M. Clark, C. Monge, C. Stanley, W.D. Brown, C.K. Stone, R.J. Nickels, and J.E. Holden. (1996b). Sherpa brain glucose metabolism and defense adaptations against chronic hypoxia. J. Appl. Physiol. 81 1355-1361. Hochachka, P.W., H.C. Gunga, and K. Kirsch (1998). Our ancestral physiological phenotype An adaptation for hypoxia tolerance and for endurance performance Proc. Natl. Acad. Sci. USA 95 1915-1921. 

Epithelial microcysts are an abnormal corneal response at the cellular level to chronic hypoxia from contact lens wear. When present, they tend to be observed in soft contact lens wearers, particularly those wearing extended-wear lenses. A hypoxic state can result in the development of microcysts due to such causes as... 

D, Dewerchin M, Brouckaert P, Bloch KD, Janssens S. Solu- 40. ble guanylate cyclase-alphal deficiency selectively inhibits the pulmonary vasodilator response to nitric oxide and increases the pulmonary vascular remodeling response to chronic hypoxia. Circulation 2007 116 936-943. 41. 

F. Kolar and B. Ostadal, Molecular mechanisms of cardiac protection by adaptation to chronic hypoxia. Physiol. Res. 53, S3-S13 (2004). 

A diametrically different picture exists in the immature heart The chronic hypoxia to which it is subjected, renders it more resistant against ischemia.17,18 Another intriguing aspect in this state is that ischemic preconditioning is not as effective.19,20 However, it has not been adequately clarified if preconditioning does not really exist or if it is difficult to demonstrate additional protection in an intrinsically resistant heart. 

Hypoxia appears to be a common and unique property of cells in solid tumors and is a target for tumor-specific activation of anticancer prodrugs.4 It is now well known that solid tumors often contain an inefficient microvascular system, and part of solid tumors exists under a hypoxic condition.12 Hypoxia can be classified into two broad types chronic and acute. Chronic hypoxia occurs in cells that are distant from their blood supply and suffer low oxygen tension permanently. Acute hypoxia results in cells experiencing temporary cessation of blood flow. 

Del Toro R, Levitsky KL, Lopez-Barneo J, Chiara MD. 2003. Induction of T-type calcium channel gene expression by chronic hypoxia. J Biol Chem 278 22316-22324. 

Fung ML, Tipoe GL. 2003. Role of HIF-1 in physiological adaptation of the carotid body during chronic hypoxia. Adv Exp Med Biol 536 593-601. 

In lung diseases such as emphysema or chronic bronchitis, there is chronic hypoxia that is particularly obvious in vascular tissues such as the lips or nail beds (cyanosis). Poorly perfused areas exposed to chronic hypoxia have decreased metabolic energy for tissue maintenance and repair. An important reason for this is... 

Anemia is observed in some CF patients despite chronic hypoxia. The apparent deficient erythroid response occurs, at least in part, from disturbances in erythropoietin regulation and iron availabihty (impaired gastrointestinal absorption). Despite chronic hypoxia in some patients with CF, erythropoietin concentrations are normal or low. The condition is characterized by decreased hematocrit and serum ferritin, increased carboxyhemoglobin, and normal or low hemoglobin. Vitamin E concentrations may be normal. Many patients may have iron deficiency owing to decreased dietary intake, malabsorption, or blood loss. 

Rabinovitch MGW, Nadas AS, Miettinen OS, Reid L. Ratpul-monary circulation after chronic hypoxia hemodynamic and structural features. Am J Physiol 1979 236 H818-27. 

Clubbing does not occur with clients diagnosed with asthma. It occurs in clients with chronic hypoxia such as occurs with chronic obstructive pulmonary disease (COPD) or cystic fibrosis (CF). 

---