[Job conditions and the current conception of occupational health nurses in industries having fewer than 1,000 employees].

A questionnaire study was carried out on 103 occupational health nurses in small and medium industries defined as having fewer than 1,000 employees in the Kanto district from August to September, 1993. Fifty-nine (59) questionnaires were collected from occupational health nurses and nine (9) of them were interviewed. The results were as follows: 1) Many of them were engaged in jobs related to medical affairs and not satisfied with the job conditions for health guidance and medication supervision because of the absence of a doctor. 2) Many of them were engaged in jobs related to health administration affairs and not engaged in safety education or present at the health committee meetings, and were not satisfied with the job conditions in health and safety education. 3) And the results of this study suggest that there is a need for two functions in medical care--those of the clinic and the pharmacy--in industries of this size and we must discuss how this should be achieved. 4) They regarded health and safety education, health guidance and health counseling as their proper jobs as occupational health nurses.

Immunohistochemical visualization of brain-derived neurotrophic factor in the rat brain.

A purified polyclonal antibody preparation was made against recombinant brain-derived neurotrophic factor (BDNF) in guinea pig and characterized for use in immunoassays and immunohistochemistry. The anti-BDNF antibodies specifically recognized BDNF in Western blots and immunoprecipitation. There was no cross-reactivity with the other known mammalian members of the neurotrophin family, nerve growth factor, neurotrophin-3 and neurotrophin-4/5. In immunohistochemical analysis, the anti-BDNF recognized exogenous BDNF injected into the brain of rats, whereas no signal was obtained with the other neurotrophins. Preabsorption with native BDNF abolished the immunoreactivity in brain sections. These studies identify the anti-BDNF as a tool for immunocytochemistry and the development of an immunoassay. Immunohistochemical analysis revealed widespread neuronal localization of BDNF in many brain areas. BDNF was localized in all subpopulations of hippocampal neurons. The distribution in the hippocampus suggests localization in the cytoplasm of cell bodies and dendrites.

Epidermal growth factor induces PC12 cell differentiation in the presence of the protein kinase inhibitor K-252a.

The protein kinase inhibitors K-252a and K-252b have been shown earlier to block the actions of nerve growth factor and other neurotrophins and, at lower concentrations, to selectively potentiate neurotrophin-3 actions. In the present study we show that K-252a, but not K-252b, enhances epidermal growth factor (EGF)-and basic fibroblast growth factor (BFGF)-induced neurite outgrowth of PC12 cells at higher concentrations than required for neurotrophin inhibition. In parallel, tyrosine phosphorylation of extracellular signal-regulated kinases (Erks) elicited by EGF of bFGF was also increased in the presence of K-252a, and this signal was prolonged for 6 h. EGF- and bFGF-induced phosphorylation of phospholipase C-gamma 1 were not changed. The effect of K-252a on Erks was resistant to chronic treatment with phorbol ester, indicating that protein kinase C is not involved in this potentiation. In partial contrast to the actions of K-252a, the neurotrophin-3-potentiating effect of K-252b was accompanied by an increase in tyrosine phosphorylation of the Erks and of phospholipase C-gamma 1. Finally, although K-252a alone did not induce neurite outgrowth or tyrosine phosphorylation of Erks or phospholipase C-gamma 1, this compound alone stimulated phosphatidylinositol hydrolysis. Our findings identify activities of K-252a besides the direct interaction with neurotrophin receptors and suggest that a K-252a-sensitive protein kinase or phosphatase might be involved in signal transduction of EGF and bFGF. Our results are further compatible with the hypothesis that sustained activation of Erks may be important in PC12 differentiation.

Mureidomycins E and F, minor components of mureidomycins.

Mureidomycins (MRDs) E and F were isolated from a culture filtrate of Streptomyces flavidovirens SANK 60486 which produces MRDs A approximately D. They possessed the same molecular formulae, C39H48N8O12S and very similar UV, IR and NMR spectra, but differed clearly from each other in HPLC profile. From the hydrolysates of MRDs E and F, 8-hydroxy-1,2,3,4-tetrahydro-3-isoquinoline carboxylic acid and 6-hydroxy-1,2,3,4-tetrahydro-3-isoquinoline carboxylic acid were detected, respectively, which were not detected from those of MRDs A approximately D. They showed strong anti-pseudomonal activity but less active than MRD A. MRDs E and F were synthesized from MRD A and formaldehyde through Pictet-Spengler reaction.

Selective inhibition of the bacterial translocase reaction in peptidoglycan synthesis by mureidomycins.

Mureidomycins (MRDs) A and C inhibited strongly the formation of undecaprenyl pyrophosphoryl N-acetylmuramyl-pentapeptide (lipid intermediate I), which is an intermediate in bacterial peptidoglycan synthesis (50% inhibitory concentration [IC50] of MRD A, 0.05 microgram/ml). However, they did not inhibit the formation of dolichyl pyrophosphoryl N-acetylglucosamine (Dol-p-p-GlcNAc), dolichyl phosphoryl glucose, or dolichyl phosphoryl mannose, the precursors for mammalian glycoprotein synthesis, or the formation in Bacillus subtilis of lipid-linked N-acetylglucosamine for teichoic acid synthesis (IC50s, > 100 micrograms/ml). In contrast, tunicamycin (TCM) inhibited strongly the formation of Dol-p-p-GlcNAc (IC50, 0.03 microgram/ml) but inhibited weakly the formation of bacterial lipid intermediate I (IC50, 44 micrograms/ml). When the effects of MRDs A and C and TCM on the growth of mammalian cells were compared, MRDs did not show any toxicity, even at 1,000 micrograms/ml, whereas TCM inhibited the growth of BALB/3T3 cells at 10 micrograms/ml. On the basis of these results, it was concluded that MRDs are the first specific and potent inhibitors of the translocase reaction in bacterial peptidoglycan synthesis, showing a high level of toxicity against bacteria and a low level of toxicity against mammalian cells. A specific inhibitor of translocase could be a potent antibiotic with highly selective toxicity.

Susceptibility of Pseudomonas species to the novel antibiotics mureidomycins.

Strains of Pseudomonas aeruginosa, including imipenem- or ofloxacin-resistant clinical isolates, and some other species in the genus Pseudomonas were inhibited by novel antibiotics of the mureidomycin (MRD) group. On the other hand, almost all other gram-positive and gram-negative bacteria were resistant to MRDs, though the antibiotics potently inhibited the in vitro peptidoglycan synthesis of Escherichia coli and P. aeruginosa. All of the strains in the genus Pseudomonas that were inhibited by less than or equal to 200 micrograms of MRDs per ml were classified into the rRNA groups I and III, and none of the tested strains of rRNA group I were resistant to MRDs, suggesting that these two groups are closely related to each other evolutionary. Among group I strains, P. aeruginosa, P. mendocina, P. stutzeri, and P. alcaligenes were more susceptible than the others, suggesting a closer relationship among these species.

Mureidomycin A, a new inhibitor of bacterial peptidoglycan synthesis.

Mureidomycin A (MRD), a novel peptidylnucleoside antibiotic with antipseudomonal activity, inhibited not only peptidoglycan synthesis but also lipid-intermediate formation from UDP-N-acetylmuramyl (MurNAc)-pentapeptide and UDP-N-acetylglucosamine in an in vitro peptidoglycan-synthesizing system, using ether-treated cells of Pseudomonas aeruginosa. Both types of inhibition by MRD disappeared when UDP-MurNAc-pentapeptide was preincubated with ether-treated cells. Moreover, MRD completely inhibited lipid-intermediate I (undecaprenyl-p-p-MurNAc-pentapeptide) formation at a concentration below the MIC. From these results, it was concluded that the real target of MRD's action was translocase, which catalyzes lipid-intermediate I formation from UDP-MurNAc-pentapeptide and a lipid carrier.

Mureidomycins A-D, novel peptidylnucleoside antibiotics with spheroplast forming activity. I. Taxonomy, fermentation, isolation and physico-chemical properties.

A strain of actinomycetes identified as Streptomyces flavidovirens produced new antibiotics, mureidomycins (MRD's) A approximately D, specifically active against Pseudomonas aeruginosa. They were isolated from the culture filtrate by successive column chromatographies such as Amberlite XAD-2 and CG-50, Whatman DE-52 and Toyopearl HW-40. They were amphoteric white powders and soluble in methanol and water. Their molecular weights and molecular formulae in parentheses were 840 (C38H48N8O12S), 842 (C38H50N12S), 897 (C40H51N9O13S) and 899 (C40H53N9O13S), respectively. m-Tyrosine and two unknown substances were detected by amino acid analyses as their common constituents. MRD's A and C contained uracil but MRD's B and D dihydrouracil instead of uracil.

Mureidomycins A-D, novel peptidylnucleoside antibiotics with spheroplast forming activity. II. Structural elucidation.

Structures of new antibiotics, mureidomycins (MRD's) A approximately D, were deduced from spectroscopic analyses and degradation studies. Two residues of m-tyrosine, one residue of 2-amino-3-N-methylaminobutyric acid (AMBA) and methionine are present in all components of the complex. Uracil is contained in MRD's A and C, while dihydrouracil in MRD's B and D. Methionine and m-tyrosine are connected through an ureido bond, and uracil or dihydrouracil is linked to AMBA via enamine sugar moiety. In addition, MRD's C and D contain a glycine residue at the N-terminal.

Mureidomycins A-D, novel peptidylnucleoside antibiotics with spheroplast forming activity. III. Biological properties.

Mureidomycins (MRD's) A-D were specifically active against Pseudomonas aeruginosa. Among them, MRD C was most active, with MICs of 0.1 to 3.13 micrograms/ml against many strains of the target organism. Its activity was comparable to that of cefoperazone, ceftazidime and cefsulodin. MRD C-resistant mutants of P. aeruginosa appeared spontaneously at a high frequency when cultured in the presence of the antibiotic. No cross-resistance was observed with beta-lactam antibiotics. A rapid decrease of turbidity along with spheroplast formation and cell lysis was observed when cells of P. aeruginosa were grown in the presence of MRD C. The compounds exhibited low toxicity and protected mice from experimental infection with P. aeruginosa. The urinary and fecal recoveries of MRD C given subcutaneously were 5 and 18%, respectively.

Lactoquinomycin, a novel anticancer antibiotic. I. Taxonomy, isolation and biological activity.

Lactoquinomycin, a novel basic antibiotic, was isolated from the culture broth of a soil streptomyces by repeated solvent extraction and adsorption column chromatography. Morphological, cultural and physiological studies revealed that the organism belongs to the species Streptomyces tanashiensis. The antibiotic was active against bacteria, particularly Gram-positive organisms, and neoplastic cells in vitro. Antibiotic-resistant cell sublines of L5178Y lymphoblastoma were more significantly inhibited by lactoquinomycin than the parental cell line. Lactoquinomycin was effective against Ehrlich carcinoma in mice.

Studies on antineoplastic activity of naphthomycin, a naphthalenic ansamycin, and its mode of action.

An antibiotic, identical with naphthomycin, was isolated from a soil Streptomyces. The antibiotic displayed significant therapeutic activity by ip administration against murine tumors: Ehrlich carcinoma and IMC carcinoma implanted ip. The maximum increase of life-span was more than 169% in Ehrlich carcinoma, and 128% in IMC carcinoma. The antibiotic exhibited a potent cytotoxicity against murine leukemic cells: P388, L1210, and L5178Y. IC50 was 0.4-1.3 microgram/ml in culture. The activity of naphthomycin was reversed by SH compounds: 2-mercaptoethanol, dithiothreitol, and glutathione. DNA and RNA syntheses were more markedly inhibited by naphthomycin than protein synthesis in L5178Y cells. Approximately 50% inhibition of nucleic acid syntheses was observed at an antibiotic concentration of 2 micrograms/ml. Naphthomycin blocked alkaline phosphodiesterase obtained from L5178Y cells: IC50 was ca. 7.6 micrograms/ml. The antibiotic neither caused metaphase arrest nor prevented tubulin polymerization. The results suggest that the mechanism of cytotoxicity of naphthomycin is the inhibition of various SH enzymes, particularly those involved in nucleic acid biosynthesis. The mode of action is unique in the ansamycin group of antibiotics.