Inhibition of wheat embryo calcium-dependent protein kinase and avian myosin light chain kinase by flavonoids and related compounds.

Avian myosin light chain kinase (MLCK) is inhibited by a range of plant-derived flavonoids. Maximal inhibition requires 2,3-unsaturation and polyhydroxylation of two of the three flavonoid rings. Phosphorylation of a synthetic myosin light chain-related peptide by wheat embryo Ca(2+)-dependent protein kinase (CDPK) is also inhibited by a range of flavonoids but phosphorylation of histone preparation III-S by wheat CDPK is not inhibited by flavonoids. The structural requirements for inhibition of wheat CDPK by flavonoids are more stringent than for inhibition of avian MLCK. Potent flavonoid inhibitors of wheat CDPK are unsaturated in 2,3 position, have hydroxyl groups in positions 3' and 4' and an additional hydroxyl in the chromone ring. Flavonoid glycosylation or methylation can abolish inhibition. A number of other naturally occurring plant phenolics including chalcones and gossypol also inhibit avian MLCK and wheat CDPK. Gossypol binds to calmodulin, abolishing Ca(2+)-dependent enhancement of dansyl-calmodulin fluorescence.     

Effect of prenatal ethanol exposure on postnatal neural gene expression in the rat.

To examine the effects of ethanol exposure on neural development, pregnant rats were fed a liquid diet in which 37.5% of the total caloric content was ethanol-derived. The developmental appearance of the messenger RNAs coding for preprosomatostatin, glial fibrillary acidic protein, and proteolipid protein was examined by Northern blotting of total cellular RNA obtained from forebrain and hindbrain at various times after birth. In general, there was a delay in the developmental pattern of appearance of these mRNAs which was most noticeable at the early postnatal times. These results suggest that the previously reported delay in neural maturation is reflected at the level of the gene expression.     

Induction of gene expression in Dictyostelium by prestarvation factor, a factor secreted by growing cells

During growth, Dictyostelium cells continuously secrete a factor, PSF, that accumulates in proportion to cell density. At sufficient concentration, it triggers the production of discoidin I and certain lysosomal enzymes. Our earlier studies demonstrated these effects of PSF on protein and enzyme levels [Clarke et al., Differentiation 34:79-87, 1987; Clarke et al., Dev Genet 9: 315-326, 1988]. In the present study, we have examined whether PSF induces increased mRNA levels. By Northern blot analysis, we have found that discoidin I mRNA accumulates in exponentially growing NC4 cells as the cells reach high density; significant levels of mRNA are detectable in cells growing either on plates or in suspension, beginning about four generations before the end of exponential growth. High levels of discoidin I mRNA are also found in low-density cells grown in the presence of buffer conditioned by high-density cells. These results indicate that PSF induces the accumulation of discoidin I mRNA. Other "early developmental" genes, pCZ22 and the early I genes (16, 18, and 111), are also expressed in exponentially growing cells at high density or in the presence of conditioned buffer. We conclude that several genes previously found to be preferentially expressed very early in development are actually induced during late exponential growth by PSF.     

Comparison of two cytochromes P-450 from Candida maltosa: primary structures, substrate specificities and effects of their expression in Saccharomyces cerevisiae on the proliferation of the endoplasmic reticulum

cDNAs were cloned, sequenced and expressed which encode two different cytochrome P-450 forms of the alkane-assimilating yeast Candida maltosa, designated as P-450Cm1 and P-450Cm2. The amino acid sequences deduced were about 55% identical. Expression in Saccharomyces cerevisiae resulted in the formation of intact microsomal P-450 systems catalyzing the hydroxylation of n-hexadecane and lauric acid with significantly different substrate preferences. A massive proliferation of the endoplasmic reticulum was observed in the S. cerevisiae cells which produced P-450. Depending on the P-450 form expressed, distinctly organized stacks of paired membranes appeared and occupied considerable areas of the cytoplasm. As shown by immunoelectron microscopy for P-450Cm1, the protein expressed was highly concentrated within these newly formed membrane structures.     

NK-1 receptors are the only class of tachykinin receptors found on mouse cortical astrocytes.

Extending our previous studies, our results indicate that cultured cortical astrocytes from the mouse possess only NK-1 receptors coupled to phospholipase C. An excellent correlation was found in the potency of tachykinins and selective analogs at inhibiting 125I-BHSP binding and at stimulating phospholipase C activity, their rank order being that of NK-1 receptors. No binding sites could be found with ligands of NK-2 or NK-3 receptors. No additive effect could be shown with NK-2 or NK-3 agonists when phospholipase C activity was estimated with high concentrations of NK-1 agonists. C- or N-terminal SP fragments did not modify SP- or [Pro9]SP-evoked responses.     

Protein expression of Yersinia pestis during changes due to long-term cultivation in vivo]

The electrophoretic study of Yersinia pestis proteins made possible to find the significant modification of Yersinia pestis polypeptide specters when the bacteria were cultivated in semi-penetrable cells implanted into the guinea pigs peritoneum. The proteinogramms of the isolates from the implanted cells lacked the stained bands characteristic of Yersinia pestis cells grown in vitro and contained the new polypeptides absent from the bacteria grown on the Hottinger agar plates. The difference was found at the late stage of bacteria incubation in implanted cells and had the predominantly reversible characteristics. The protein of Yersinia pestis being changed in vivo is proposed to be the species specific fraction I.     

Role of the mucous barrier in the pathogenesis of stress ulcers of the stomach

Using the model of immobilizing stress in rats, it has been established that the content of sialic acids in the stomach mucous membrane (SMM) and blood serum rises with simultaneous activation of proteolytic enzymes in them. The preliminary adaptation to short stressor influences parallel with an antipathogenic effect normalizes the content of sialic acids in the blood serum and SMM. The conclusion is made on the essential role of the degradation of gastric mucus in pathogenesis of stress ulcers.     

Effective reconstitution of sarcoplasmic reticulum Ca2+-ATPase using lubrol PX]

Ca2(+)-ATPase of sarcoplasmic reticulum was reconstituted in the proteoliposomes by the salting out procedure. Triton X-100, C12E8 and Lubrol PX were used for the solubilization of the Ca2(+)-ATPase. Using fluorescent probes (diS-C3-(5), chlortetracycline) as well pH-measuring method, the functional of the reconstituted Ca2(+)-ATPase was comparatively studied in three types of proteoliposomes. The efficiency of Ca2(+)-ATPase grew in the following detergent order: Triton X-100, C12E8, Lubrol PX.     

Helicobacter pylori in Barrett's esophagus.

Barrett's esophagus is an anatomicoclinical state in which, due to the prolonged action of gastroesophageal reflux, the squamous epithelium is replaced by columnar epithelium. Helicobacter pylori has been implicated in the pathogenesis of various gastrointestinal disorders and has occasionally been observed in Barrett's esophagus. The aim of this study is to determine the incidence of H. pylori in Barrett's esophagus and try to establish its role in the pathogenesis of this disorder. H. pylori was observed in 31 biopsies (44.3%) of the 70 studied, mainly when the epithelium is of the gastric atrophic-fundic type (p less than 0.01). Its presence shows no relation to the degree of inflammatory activity and does not seem, therefore, to play an important role in the pathogenesis of the lesion.     

Study of the immunotropic activity of aminoglycoside antibiotics

The action of some aminoglycoside antibiotics on the immune system was studied on both intact mice and the animals with immune deficiency caused by administration of cyclophosphamide. The following tests were used: local hemolysis (the Herne test), lymphocyte transformation (LT), delayed hypersensitivity to sheep red blood cells and the local graft versus host reaction (GVHR). Amikacin was shown to have no significant action on the activity of lymphocytes in the intact mice and stimulated both cellular (LT and GVHR) and humoral (the Herne test) immunity in the animals with lowered immunological reactivity. Sisomicin had no significant action on the immune system of the animals. Gentamicin suppressed the immune response only in the intact mice. Kanamycin and streptomycin induced inhibition of humoral and cellular immunity in both the intact mice and animals with immune deficiency. On the basis of the results it was concluded that gentamicin, amikacin and sisomicin may be used in the treatment of diseases developing in the presence of immune deficiency whereas streptomycin and kanamycin should be recommended when inhibition of the immunity is needed.