Crypt

Diethjidithiocarbamate [20624-25-3] (DDC) is both an inhibitor of SOD and a thiol, and exerts both radiosensitizing and radioprotective properties in mice, depending on factors such as the time of its adniinistration relative to irradiation. For neutrons, DDC shows only protective effects (141). DDC (1 mg/g ip) given 30 min before 15 Gy (1500 rad) also protects mouse jejunal crypt ceUs and reduces the frequency of micronuclei in splenic lymphocytes (134). 

SCE protects mice from G1 death after kradiation and increases the number of surviving mucosal crypt stem cells (186) in a manner similar to lL-1. 

PGE andDenvatives. PGE2 and several related PGs protect against radiation injury in the rodent intestine with respect to both crypt clonogen survival and LD Q g Protection of hemopoietic tissue has also been reported using the exogenous CEU-S assay (215), and 40 p.m of 16,16-dimethyl PGE2... 

Chapter 8 Macrobicyclic, macrotricyclic, or polycyclic compounds including crypt-ands, spherands, etc. 

Chem. 23, 770-4 (1994) this also describes the synthesis and structure of [K(crypt)] 2[Sb4] which features the square planar [864] anion with Sb-Sb 275 pm. 

Figure 17.15 The structure of (a) the nonlinear p" cation in laAsFg and (b) the weaker cation-anion interactions along the chain (cf Fig. 17.13). For comparison, the dimensions of (c) the linear 22-electron cation L" and (d) the nonlinear 20-electron cation Te3 are given. The data for this latter species refer to the compound [K(crypt)]2Te3.en in K2Tc3 itself, where there are stronger cation-anion interactions, the dimensions are r = 280 pm and angle = 104.4°).

HFE has been shown to be located in cells in the crypts of the small intestine, the site of iron absorption. There is evidence that it associates with P2 niicroglobu-lin, an association that may be necessary for its stability, intracellular processing, and cell surface expression. The complex interacts with the transferrin receptor (TfR) how this leads to excessive storage of iron when HFE is altered by mutation is under close smdy. The mouse homolog of HFE has been knocked out, resulting in a potentially useful animal model of hemochromatosis. 

SMITH T K, LUND E K and JOHNSON I T (1998) Inhibition of dimethylhydrazine-induced aberrant crypt foci an induction of apoptosis in rat colon following oral administration of the glucosinolate sinigrin , Carcinogenesis, 19, 267-73. 

CHUNG F L, CONAWAY c c, RAO c V and REDDY B s (2000) Chemoprevention of colonic aberrant crypt foci in Fischer rats by sulforaphane and phenethyl isothiocyanate . Carcinogenesis, 21 2287-91. 

SMITH T, MUSK s R and JOHNSON I T (1996) Allyl isothiocyanate selectively kills undifferentiated HT29 cells in vitro and suppresses aberrant crypt foci in the colonic mucosa of rats , Biochem Soc Trans, 24 381S. 

REDDY B s, HAMID R, RAO c V (1997) Effect of dietary fiber ohgofmctose and inilin on colonic preneoplastic aberrant crypt foci inhibition. Carcinogenesis. 18 1371-4. 

ROLAND I R, RUMNEY 0 J, couTTS J T, LiEVENSE L c (1998) Effect of Bifidobactcrium longum and inulin on gut bacterial metabolism and carcinogen-induced crypt foci in rats. ... 

VERGHESE M, RAO D R, CHAWAN C B, WILLIAMS L L, SHACKELFORD L (2002) Dietary inului suppresses azoxymethane-induced aberrant crypt foci and colon tumors at the promotion stage in young fisher 344 rats. J. Nutr. 132 2809-2813. 

The physiological role of the ICOR is not clear and may be heterogeneous in the various tissues. In the thick ascending limb of the loop of Henle this channel appears to serve as the exit for CP at the basal cell pole [16,65,66], This conductive mechanism, therefore, is required for the reabsorption of Na and CP by this segment of the nephron [16]. In the rectal gland of Squalus acanthias a very similar channel is utilized for Na" and CP secretion. In these latter cells the CP-channel is present in the luminal membrane and is controlled by cytosolic cAMP [15,56,71]. It has been claimed that this kind of channel is also responsible for the secretion of CP in the colonic crypt cell, in colonic carcinoma cells and in respiratory epithelial cells [17,19,20,22]. Recent data have cast some doubt on this concept ... 

I have noted that NPPB is structurally related to loop diuretics of the furosemide (Fig. 2) type. These latter compounds bind to the Na 2CNK -cotransporter [16] and inhibit NaCl reabsorption in the TAL segment and NaCl secretion in epithelia such as the colonic crypt cell and rectal gland of Squalus acanthias [15]. We were able to show that only minor modification of the NPPB molecule on one side and of furosemide on the other led to compounds with altered selectivities [70,91-93]. One prototype of an intermediate blocker, i.e., a substance blocking both Na 2Cl K -cotransport and CP-channels, is torasemide (Fig. 2). Hence we have performed a systematic study in order to define the constraints defining the effectiveness of this class of substances [91]. 

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