Inhibition of conversion

With preformed ACP at ratios of only one PL molecule per 30-50 Ca atoms, phosphatidyl serine markedly delays HA crystal formation. When phosphatidyl serine is present during ACP precipitation, inhibition of conversion to HA is less pronounced, but crystal habit and aggregation are greatly altered resulting in stacks of thin, membrane-like sheets approximately 3—42 A thick. Phosphatidyl serine... 

Heparin-induced hypoaldosteronism is well documented, both in patients treated with standard heparin, even at low doses, and in patients treated with low molecular weight heparin (477,478). The most important mechanism of aldosterone inhibition appears to be a reduction in both the number and affinity of angiotensin II receptors in the zona glomerulosa (477). A direct effect of heparin on aldosterone synthesis, with inhibition of conversion of corticosterone to 18-hydroxycorticosterone, has also been suggested. This effect is believed to be responsible for the hyperkalemia that can occur in heparin-treated patients with impaired renal function and particularly in patients on chronic hemodialysis (479), or with diabetes mellitus, or who are taking other potentially hyperkalemic drugs. 

Renz JF, Kalf GF. 1991. Role for interleukin-1 (IL-1) in benzene-induced hematotoxicity inhibition of conversion of pre-IL-1 alpha to mature cytokine in murine macrophages by hydroquinone and prevention of benzene-induced hematotoxicity in mice by IL-1 alpha. Blood 78(4) 938-944. 

M. Horiuchi, S. A. Priola, J. Chabry, et al. Interactions between heterologous fortms of prion protein binding, inhibition of conversion, and species barriers. Proceedings of the Society of National Academy of Sciences (USA) 97,5836 (2000). 

Inhibition of conversion of LDL to oxidized LDL which is preferentially taken up by the tissue macrophages,... 

Inhibition of Conversion of Ribonucleoside Diphosphate to Deoxyribonucleoside Diphosphate... 

Immune system dysfunction in ADA deficiency has also been ascribed to the inhibition of pyrimidine nucleotide synthesis by adenosine, known as pyrimidine starvation. This may arise from inhibition of conversion of orotic acid to orotidine 5 -monophosphate or from inhibition of PRPP synthesis by excessive synthesis of adenine nucleotides. 

Because many of the manifestations of hyperthyroidism are mediated by /S-adrenergic receptors, /3-blockers (especially propranolol) have been used widely to ameliorate thyrotoxic symptoms such as palpitations, anxiety, tremor, and heat intolerance. Although /S-blockers are quite effective for symptom control, they have no effect on the urinary excretion of calcium, phosphorus, hydroxypro-line, creatinine, or various amino acids, suggesting a lack of effect on peripheral thyrotoxicosis and protein metabolism. Furthermore, /3-blockers do not reduce TSAb nor prevent thyroid storm. EYopra-nolol and nadolol partially block the conversion of T4 to T3, but this contribution to the overall therapeutic effect is small in magnitude. Inhibition of conversion of T4 to T3 is mediated by rf-propranolol, which is devoid of /3-blocking activity, and /-propranolol, which is responsible for the antiadrenergic effects and has little effect on the conversion. 

Kakiki et ai. (1969) reported that EBP inhibited the incorporation of glucosamine-into the cell wall of Piricularia orysae. This suggested that a mode of action of this compound might be the inhibition of chitin biosynthesis. According to the experiments of Akatsuka et al. (1977) and of Kodama et al. (1979) the specific inhibition of conversion from phosphatidylethanolamine to phos-phatidylcholin by the transmethylation of S-adenosylmethionine might be one of the modes of action of IBP. 

Effects Inhibition of conversion to uric acid increases the concentrations of the more soluble hypoxanthine and xanthine and decreases the concentration of the less soluble uric acid. As a result, there is less likelihood of precipitation of uric acid crystals in joints and tissues. 

The adrenergic symptoms of hyperthyroidism, such as palpitation, tremor, anxiety, or heat intolerance are promptly relieved by coadministration of betablockers. Nonselective betablockers, such as propanolol, are preferred because of their more direct effect on hypermetabolism with positive effect of tremor or myopathy and the peripheral inhibition of conversion from T4 to T3 (Nolte 1995). The dose should be increased progressively until symptoms are controlled. Betablockers should be used cautiously in patients with intrinsic asthma or congestive heart failure. 

Carter JN, Eastmen CJ, Corooran JM, et al. Inhibition of conversion of thyroxine to triiodothyronine in patients with severe ohronio illness. Clin Endoorinol 1976 5 587-594. 

Some laboratories (64 M) have found PChlide to be the primary porphyrin to accumulate in diphenyl ether-treated tissues. In our green cucumber cotyledon disc system, we have found only PPIX levels to be increased by these herbicides (67), however, in intact cucumber seedlings (Fig. 5) and tentoxin-affected cucumber cotyledon discs ( S) we found diphenyl ether-enhanced PChlide levels. PPIX levels accumulate to many (as much as several hundred) times the control levels in herbicide-treated tissues, whereas the maximum PChlide accumulation is only four-fold that of the control. Since the metabolic block is at Protox, there is no inhibition of conversion of PChlide to Chi after exposure to light. Therefore, it seems unlikely that PChlide plays a significant part in the mechanism of action of these herbicides. Indeed, of the Chi precursors assayed, only PPIX significantly correlated with herbicidal damage caused by a several different acifluorfen/DP/ALA treatment combinations ( 7). No significant correlations were found with accumulated PChlide,... 

Bredinin, Neosidomycin, and SF-2140. Bredinin (62), isolated from the culture filtrates of Eupenicillium brefeldianum (1,4), inhibits the multiplication of L5178Y, HeLa S3, RK-13, mouse L-ceUs, and Chinese hamster cells. GMP can reverse the inhibition by (62), but (62) is not incorporated into the nucleic acids. The inhibition of nucleic acid synthesis and chromosomal damage in the S and G 2 phases that is caused by (62), is reversed by GMP. It blocks the conversion of IMP to XMP and XMP to GMP. In combination with GMP, (62) interferes with intracellular cAMP levels and thereby inhibits cell division. 

Many researchers have correlated the overall decomposition as an nxh. order reaction, with most paraffins following the first order and most olefins following a higher order. In general, isoparaffin rate constants are lower than normal paraffin rate constants. The rate constants are somewhat dependent on conversion due to inhibition effects that is, the rate constant often decreases with increasing conversion, and the order of conversion is not affected. This has been explained by considering the formation of aHyl radicals (38). To predict the product distribution, yields are often correlated as a function of conversion or other severity parameters (39). 

It has been reported that below about 370°C, sulfur oxides reversibly inhibit CO conversion activity. This inhibition is greater at lower temperatures. CO conversion activity returns to normal shortly after removal of the sulfur from the exhaust (44). Above about 315°C, sulfur oxides react with the high surface area oxides to disperse the precious-metal catalytic agents and irreversibly poison CO conversion activity. 

In view of the well-documented inhibition of dihydrofolate reductase by aminopterin (325), methotrexate (326) and related compounds it is generally accepted that this inhibitory effect constitutes the primary metabolic action of folate analogues and results in a block in the conversion of folate and dihydrofolate (DHF) to THF and its derivatives. As a consequence of this block, tissues become deficient in the THF derivatives, and this deficiency has many consequences similar to those resulting from nutritional folate deficiency. The crucial effect, however, is a depression of thymidylate synthesis with a consequent failure in DNA synthesis and arrest of cell division that has lethal results in rapidly proliferating tissues such as intestinal mucosa and bone marrow (B-69MI21604, B-69MI21605). 

The effect of conversion is mostly an economic indicator. Additionally, a strong slowdown can indicate a reversible reaction. If this possibility is excluded by thermodynamic estimates, a strong inhibition of the rate is... 

Johnson has described a method for the estimation of physostigmine in the salicylate for the determination of minute amounts of the alkaloid Ellis, Plaehte and Straus have devised processes depending on (a) inhibition of serum choline-esterase by the alkaloid, or (b) measurement of the colour intensity produced by the conversion of physostigmine to rubreserine in an alkaline medium. i ... 

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