Impaired transport

Ineffective Tissue Perfusion related to hypovolemia, blood loss, impaired distribution of fluid, impaired circulation, impaired transport of oxygen across alveolar and capillary bed, other (specify)... 

Granas, C., Ferrer, J., Loland, C. J., Javitch, J. A. and Gether, U. N-terminal truncation of the dopamine transporter abolishes phorbol ester- and substance P receptor-stimulated phosphorylation without impairing transporter internalization. /. Biol. Chem. 278 4990-5000, 2003. 

The structure of the rice root is therefore apparently dominated by the need for internal gas transport. On the face of it, this structure may conflict with the needs for efficient nutrient absorption (Kirk and Bouldin, 1991). The development of gas-impermeable layers in the root wall seems likely to impair the ability of those parts of the root to absorb nutrients, and the disintegration of the cortex might impair transport from the apoplasm to the main solute transport vessels in the stele, though these points are uncertain (Drew and Saker, 1986 Kronzucker et al, 1998a). It seems likely that the short fine lateral roots are responsible for the bulk of the nutrient absorption by the root system and compensate for any impairment of nutrient absorption by the primary roots as a result of adaptations for internal aeration. 

Although it has been known for several years that leptin can activate AMPK, recently this pathway has come into focus as it was demonstrated to be of utmost importance in regulating food intake in the hypothalamus (Minokoshi et al. 2002, 2004). AMPK plays a particularly important role in the regulation of fatty acid oxidation. Fatty acids which are not oxidized are stored in cytoplasm as triglycerides. Malonyl CoA is an important fatty acid in maintaining a balance between storage of fatty acids and transport into the mitochondria for oxidation. Elevated malonyl CoA results in impaired transport into the mitochondria and consequently... 

Impaired transport Abetalipoproteinaemia Addison s disease Blocked lacteals - lymphoma, mberculosis Lymphangiectasia... 

The absorption of thiamin is impaired in alcoholics, leading to thiamin deficiency (Section 6.4.4). In vitro, tissue preparations show normal uptake of the vitamin into the mucosal cells in the presence of ethanol, but impaired transport to the serosal compartment. The sodium-potassium-dependent ATPase of the basolateral membrane responsible for the active efQux of thiamin into the serosal fluid is inhibited by ethanol (Hoyumpa et al., 1977). 

NET A457P Impaired transport, decreased cell Orthostatic intolerance, increased... 

Blocked assets. The presence of a fuel molecule in the cytosol does not ensure that it can be effectively used. Give two examples of how impaired transport of metabolites between compartments leads to disease. 

Methotexate is an antineoplastic folic add analogue that blocks the conversion of dihydrofolate (FHj) to tetrahydro-folate (FH4) by binding to dihydrofolate reductase (DHFR) enzyme. Folate is essential for the normal synthesis of purines and pyrimidines, and therefore DNA and RNA. In order for folate to function as a cofactor, it must be reduced to FH by DHFR. Methotrexate binds to DHFR, prevents the conversion of FH2 to FH4, and, consequently, inhibits purine and pyrimidine synthesis. The antimetabolites are considered cell cycle specific, with most activity for cells in the S (synthesis) phase. With high-dose methotrexate, leucovorin rescue is often used to prevent severe toxicity to normal body tissues. Leucovorin (folinic acid) is a reduced form of folate (similar to FH ) that does not require the use of DHFR. Leucovorin is transported into healthy cells and is utilized for DNA and RNA synthesis. Tumor cells tend to have impaired transport mechanisms and usually cannot use leucovorin. Leucovorin is usually started within 24 to 36 hours of high-dose methotrexate administration and continues until methotrexate serum levels are below nontoxic levels (0.1 to 0.05 mol/L). 

AD has been associated with decreased CSF levels of insulin in combination with decreased insulin sensitivity (insulin resistance) in the brain. Attenuated receptor expression of insulin and insulin-like growth factor, enhanced serine phosphorylation of insulin receptor substrate-1, and impaired transport of insulin across the BBB are pathogenic events underlying brain insulin resistance. Some clinical trials have demonstrated that intranasal insulin improves memory performance of patients with AD and MCI [517]. 

Hori Y, Takeyama Y, Lfeda T et al (1998) Impaired transport of lipopolysaccharide across the hepatocytes in rats with cerulein-induced experimental pancreatitis. Pancreas 16 148-153... 

The central nervous system is the primary target of manganese toxicity. Although it is known that manganese is a cellular toxicant that can impair transport systems, enzyme activities, and receptor functions, the principal manner in which manganese neurotoxicity occurs has not been clearly established (Aschner and Aschner 1991). 

Since Leishmania can be cultured easily, this genus has served as an in vitro prototype for investigating drug resistance in parasitic protozoa. Two classes of drug-resistant Leishmania have been generated and characterized. The first is that in which a genetic lesion leads to impaired transport or metabolic function. Mutations in transport pathways (51) and in metabolic enzymes (52) have provided considerable insight into the avenues by which certain nutrients are metabolized in Leishmania. 

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