db—cAMP对转化细胞钙调素基因表达与细胞骨架的影响

We have demonstrated that the distribution of microtubules (MT), microfilaments (MF) and fibronectin (FN) were diminished, while the gene expression of the calmodulin and c-fos enhanced in the transformed C3 H10 T1/2 cells. After treatment with 1 mM db-cAMP for 1 hr. and 2 hrs., there was an early and rapidly reduced in gene expression of calmodulin and c-fos respectively. After db-cAMP treatment for 4-5 days, the number of Capping cells of ConA binding decreased significantly and the cell surface microvilli decreased also. The growth of treated cells was inhibited markedly. By using 4F1 cDNA probe, which is preferentially expressed in G1 phase, we have found that the db-cAMP treated cells were accumulated at G1 phase. Of particular interest is the fact that the distribution of microtubules, microfilaments and fibronectin were recovered after treatment with 1 mM db-cAMP for 6 days. It is suggested that the inhibition of proliferation, alteration of phenotype and recovery of cytoskeleton in transformed cells after treatment with db-cAMP are related to the inhibition of gene expression of calmodulin.     

The anchoring of newly synthesized adenovirus DNA to the nuclear matrix

After adenovirus infected HeLa cells were pulse labeled and pulse-chase labeled with 3H-thymidine, the nuclear matrix and DNA remaining tightly bound to the matrix were obtained by sequential cell fractionation. Measuring the radioactivity of labeled DNA indicated that newly synthesized viral DNA specifically attach to the nuclear matrix and the amount of binding DNA is in direct proportion to the viral DNA replication activity: then the DNA gradually detach from the matrix and are involved in viral assembly. Electron microscopic autoradiography of the extracted cells showed the virion and viral DNA associated with the nuclear matrix, and thus further confirmed the anchoring of newly synthesized viral DNA to the nuclear matrix.     

人型结核杆菌全染色体DNA探针鉴别结核杆菌和其安分枝杆菌

The dot-blots containing DNA isolated from nonmycobacterial and mycobacterial microorganisms were hybridized with 32P-labeled M. tuberculosis whole chromosomal DNA at the various temperatures. The probe did not cross-hybridize to DNA of nonmycobacterial microorganisms (E. coli, Plasmid pUC19, Nocardia asteriodes), nor with DNA from all mycobacteria tested except M. bovis BCG under the higher temperature conditions. Microorganisms could also be directly spotted and lysed on nitrocellulose filters and used for hybridization thus making this technique suitable for clinical diagnosis.     

福氏痢疾菌膜成分与细菌抗原性和毒力的关系

应用免疫转移技术,用从感染福氏痢疾菌的病人获取的恢复期血清分析了福氏痢疾菌膜成分与细菌抗原性和毒力的关一。发现福氏痢疾菌的膜蛋白67kD和63kD均含有两种成分,一种和膜蛋白60kD都可能是保护性抗原,而另一种与膜蛋白78kD和35kD一样与福氏痢疾菌的毒力有关。采用微细胞同位素掺入示踪显示这些与病人恢复期血清反应的膜蛋白由质粒编码。     

Sequential anaerobic degradation of 2,4-dichlorophenol in freshwater sediments.

2,4-Dichlorophenol (2,4-DCP) was anaerobically degraded in freshwater lake sediments. From observed intermediates in incubated sediment samples and from enrichment cultures, the following sequence of transformations was postulated. 2,4-DCP is dechlorinated to 4-chlorophenol (4-CP), 4-CP is dechlorinated to phenol, phenol is carboxylated to benzoate, and benzoate is degraded via acetate to methane and CO2; at least five different organisms are involved sequentially. The rate-limiting step was the transformation of 4-CP to phenol. Sediment-free enrichment cultures were obtained which catalyzed only the dechlorination of 2,4-DCP, the carboxylation of phenol, and the degradation of benzoate, respectively. Whereas the dechlorination of 2,4-DCP was not inhibited by H2, the dechlorination of 4-CP, and the transformation of phenol and benzoate were. Low concentrations of 4-CP inhibited phenol and benzoate degradation. Transformation rates and maximum concentrations allowing degradation were determined in both freshly collected sediments and in adapted samples: at 31 degrees C, which was the optimal temperature for the dechlorination, the average adaptation time for 2,4-DCP, 4-CP, phenol, and benzoate transformations were 7, 37, 11 and 2 days, respectively. The maximal observed transformation rates for these compounds in acclimated sediments were 300, 78, 2, 130, and 2,080 micromol/liter(-1)/day(-1), respectively. The highest concentrations which still allowed the transformation of the compound in acclimated sediments were 3.1 m/M 2,4-DCP, 3.1 mM 4-CP, 13 mM phenol, and greater than 52 mM benzoate. The corresponding values were lower for sediments which had not been adapted for the transformation steps.     

In vivo degradation of oxidized, regenerated cellulose

Oxidized, regenerated cellulose (ORC) was surgically implanted on the uterine horns of rabbits, and its biodegradation was studied in vivo. Samples of peritoneal lavages, serum, and urine were collected during the degradation process and analyzed for carbohydrate components utilizing high-performance liquid chromatography with pulsed amperometric detection (h.p.l.c.-p.a.d.). Degradation was rapid, and oligomeric products were evident primarily in the peritoneal fluid from the implantation site, with no apparent accumulation in either the serum or the urine. The size distribution and the amount of the oligomeric products decreased after day one, and by day four peritoneal lavages were essentially free of oligomers. The structure of the products formed was consistent with the lability of the polymer in solution, and the kinetics of degradation paralleled the results of the previously reported in vitro studies. Rabbit peritoneal macrophages, when incubated with ORC in vitro were observed to readily ingest and hydrolyze the polymeric material. A mechanism of degradation consisting of chemical depolymerization, followed by enzymatic hydrolysis mediated by glycosidases endogenous to peritoneal macrophages, is proposed.     

Stopped-flow ESR study on the reactivity of vitamin E, vitamin C and its lipophilic derivatives towards Fremy's salt in micellar systems

The reaction between Fremy's salt and alpha-tocopherol (VE), ascorbic acid (VC) and its lipophilic derivatives ascorbyl-6-caprylate (VC-8), 6-laurate (VC-12) and 6-palmitate (VC-16) were studied by stopped-flow ESR spectroscopy in cetyl trimethylammonium bromide (CTAB) and sodium dodecyl sulfate (SDS) micelles, as a model reaction of these antioxidants with alkyl peroxy radicals in biological systems. The second order rate constants for the reaction of Fremy's salt with VE in CTAB and SDS micelles were found to be 7.9 x 10(3) and 2.2 M-1 s-1, respectively, with as high as a 3600-fold variation. Rate constants for VC, VC-8, VC-12 and VC-16 are 4.3, 35, 53 and 56 x 10(3) M-1 s-1 and 3.3, 2.7, 1.2 and 0.86 x 10(3) M-1 s-1 in CTAB and SDS micelles, respectively. The results demonstrate remarkable effects of the charge type of the micelles and the side-chain of the antioxidants on the antioxidation reactivity in the micelles. It reveals that the inter-micellar diffusion may be the rate-limiting step for antioxidation carried out in micelles.     

Dynorphin immunocytochemistry in the rat central nervous system

The distribution of dynorphin in the central nervous system was investigated in rats pretreated with relatively high doses (300–400 μg) of colchicine administered intracerebroventricularly. To circumvent the problems of antibody cross-reactivity, antisera were generated against different portions as well as the full dynorphin molecule (i.e., residues 1–13, 7–17, or 1–17). For comparison, antisera to [Leu]enkephalin (residues 1–5) were also utilized. Dynorphin was found to be widely distributed throughout the neuraxis. Immunoreactive neuronal perikarya exist in hypothalamic magnocellular nuclei, periaqueductal gray, scattered reticular formation sites, and other brain stem nuclei, as well as in spinal cord. Additionally, dynorphin-positive fibers or terminals occur in the cerebral cortex, olfactory bulb, nucleus accumbens, caudate-putamen, globus pallidus, hypothalamus, substantia nigra, periaqueductal gray, many brain stem sties, and the spinal cord. In many areas studied, dynorphin and enkephalin appeared to form parallel but probably separate anatomical systems. The results suggest that dynorphin occurs in neuronal systems that are immunocytochemically distinct from those containing other opioid peptides.     

Multimers of anionic amphiphiles mimic calmodulin stimulation of cyclic nucleotide phosphodiesterase

Oleic acid, phosphatidylserine and pyrenedecanoic acid were found to activate calmodulin-deficient cyclic nucleotide phosphodiesterase at concentrations above their critical micellar concentration. In contrast with calmodulin these activators do not require the presence of Ca2+ for their action. It is shown that the size of phosphatidylserine vesicles is of crucial importance with respect to the activating potency of phosphatidylserine. Fluorescence measurements with the probe pyrenedecanoic acid revealed that micelles rather than monomers are the active species for stimulation of phosphodiesterase. There are indications that this result also may be applied to the other activators.     

Isolation and re-association of the subunits from the pro-(carboxypeptidase A)–pro-(proteinase E) binary complex from pig pancreas

The component subunits of the pro-(carboxypeptidase A)–pro-(proteinase E) binary complex from pig pancreas were separated with a high recovery (80–95%) of their original potential activity. The isolated subunits and the reconstituted complex have properties similar to those of the corresponding natural species. The tryptic activation course of the pro-(carboxypeptidase A) subunit is substantially modified when bound to pro-(proteinase E), whereas the activation of pro-(proteinase E) is not dependent on this association.