Formation and analysis of N-nitrosamines in tobacco products and their endogenous formation in consumers.
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The presence of chitin in the walls of E. invadens cysts has provided a new way to study the process of encystation, since chitin stains intensely in the presence of Calcofluor white M2R, a fluroescent dye. With this technique we have observed various stages in the differentiation of trophozoite membrane, then the cyst is formed inside the trophozoite and finally the cyst leaves the trophozoite after partial degradation of trophozoite body.
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1. In the course of 34 days the detectable methanol concentration in freshly squeezed grapefruit and organ juices as well as in grapefruit and orange juice mixes increased to a maximum level of approximately 600 mg/kg. This increase could already be detected at the beginning of the examination i.e. as early as 1 or 2 days after squeezing the fruit juices. At the beginning of the experiments the methanol concentrations were between 10 and 270 mg/kg. 2. After the consumption of pectin (40 g on one day and 2 x 40 g on two days) blood or serum-methanol values respectively were observed which were clearly above the level of chronic alcohol abuse (10 mg/kg). After the ingestion of ethanol (0.5 g/kg bodyweight) the serum-methanol concentration increased even further.
There are a difference in average values and in amplitudes of about-7 and monthly rhythms of infants' blood pressure with positive and negative family history to the hypertension. Chronobiological approach to these problem can reveal hypertension risk at the early stage of life.
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The biosynthetic step following the phosphoenolpyruvate (PEP) phosphomutase reaction which forms a C-P bond of bialaphos was proven by the identification of phosphonopyruvate (PnPy) and phosphonoacetaldehyde (PnAA) as intermediates in the culture broth of Streptomyces hygroscopicus, a producing organism of bialaphos, and by detection of enzymatic decarboxylation of PnPy to PnAA. Purified PnPy decarboxylase turned out to require thiamine diphosphate and Mg2+ as cofactors. PnPy decarboxylase drives the unfavorable forward reaction to form PnPy catalyzed by PEP phosphomutase and is suggested to be essential to C-P compound biosynthesis.
A sequence of 31 amino acids (S565-K595) in domain 6 of the light chain of high molecular weight kininogen (HK) has previously been shown to be responsible for the binding of plasma prekallikrein (PK) or kallikrein. To find effective peptides that might block binding between HK and PK on cell surfaces, a new series of synthetic peptides has now been prepared that incorporates portions of this binding domain sequence. For mapping the minimal sequence within HK, these new peptides were tested for their ability to compete with HK for binding PK in a cell-free system and on human umbilical vein endothelial cells (HUVEC). In the former, at pH 7.4, the kds for binding between kallikrein and either D567-K595, S565-P594, D567-S593, or D567-T591 were all similar to that for the binding of S565-K595 (0.2 to 0.4 micromol/L), but those for the binding of D568-K595, W569-K595, and D567-P589 were an order of magnitude greater (kd = 2 to 5 micromol/L). D567-S586, the shortest chain length of the N- and C-terminal truncation sequences tested, does not effectively compete with kininogen for kallikrein binding (kd = 100 micromol/L). These results imply that D567-T591, a 25-residue peptide (HK25c), contains sufficient structural information for binding kallikrein in solution. D567-T591 also is the minimum structural sequence to block binding of kallikrein to HUVEC-bound HK (IC50 = 50 nmol/L) and to inhibit PK activation to kallikrein on the cell surface (IC50 = 80 nmol/ L). In addition, D567-T591 also inhibits the generation of kallikrein-activated urokinase, which activates plasminogen to plasmin (IC50 = 100 nmol/L). Thus, HK-derived peptides may be useful compounds for modulating excessive fibrinolysis and hypotension in sepsis and multiple trauma.
The biosynthetic step following the phosphoenolpyruvate (PEP) phosphomutase reaction which forms a C-P bond of bialaphos was proven by the identification of phosphonopyruvate (PnPy) and phosphonoacetaldehyde (PnAA) as intermediates in the culture broth of Streptomyces hygroscopicus, a producing organism of bialaphos, and by detection of enzymatic decarboxylation of PnPy to PnAA. Purified PnPy decarboxylase turned out to require thiamine diphosphate and Mg2+ as cofactors. PnPy decarboxylase drives the unfavorable forward reaction to form PnPy catalyzed by PEP phosphomutase and is suggested to be essential to C-P compound biosynthesis.
Recent advances in action of bone morphogenetic protein (BMP), a member of TGF-beta superfamily, in the differentiation process of mesenchymal cells such as osteoblasts, chondrocytes, bone marrow stromal cells and muscle cells have been reviewed. BMPs induce osteoblast differentiation of various types of cells including undifferentiated mesenchymal cells, bone marrow stromal cells and preosteoblasts. BMPs not only inhibit myogenic differentiation but also convert differentiation pathway of some myogenic cells into an osteoblast lineage. The regulatory mechanism of BMP action discovered in the process of early embryogenesis is also reviewed; noggin, chordin and follistatin inhibit BMP action by specifically binding to BMPs.