The role of UV light-induced photoproducts in initiating base substitution mutation in human cells was examined by determining the frequency and spectrum of mutation in a supF tRNA gene in a shuttle vector plasmid transfected into DNA repair deficient cells (xeroderma pigmentosum complementation group A). To compare the role of two major UV-induced photoproducts, cis-syn cyclobutane-type pyrimidine dimers (CPDs) and pyrimidine (6-4) pyrimidone photoproducts (6-4PPs), each photoproduct was removed from UV-irradiated plasmid by photoreactivation before transfection. Removal of either CPDs or 6-4PPs by in vitro photoreactivation reduced the mutation frequency while keeping the mutation distribution and the predominance of G:C-A:T transitions as UV-irradiated plasmid without photoreactivation, indicating that both cytosine-containing CPDs and 6-4PPs were premutagenic lesions for G:C-A:T transitions. On the other hand, A:T-G:C transitions were not recovered from plasmids after the removal of 6-4PPs, whereas this type of mutation occurred at a significant level (11%) after the removal of CPDs. Thus, the premutagenic lesions for the A:T-G:C transition are 6-4PPs. Removal of both CPDs and 6-4PPs resulted in the disappearance of mutational hot spots and random distribution of mutation as observed in unirradiated control plasmids. However, the mutational spectrum of photoreactivated plasmids differed significantly from that of unirradiated plasmids. A characteristic feature is a high portion of A:T-T:A transversions (11%) in the photoreactivated plasmid. This mutation is due to nondipyrimidinic "minor" photoproducts, and the mutation spectrum suggests that TA*, the major photoproduct of thymidylyl-(3'-5')-deoxyadenosine, is the premutagenic lesion for this mutation. This is the first report revealing the distinct mutagenic roles of the major UV photoproducts and "minor" photoproducts by the use of (6-4)photolyase.
ABSTRACT A metagenomic library of activated sludge was screened for bleomycin resistance genes. Two genes were identified that differed greatly from each other, from the genes of bleomycin-producing actinomycetes, and from those of clinical isolates. Therefore, the nonclinical environment is a rich reservoir of new resistance elements, and metagenomics can be used to sample the resistome rapidly.
Journal Article Suppression of Tumor Promoter-induced Inflammation of Mouse Ear by Ursolic Acid and 4,4-Dimethylcholestane Derivatives Get access Mitsuru Hirota, Mitsuru Hirota Department of Bioscience and Biotechnology, Faculty of Agriculture, Shinshu University, 8304 Minami-minowa, Kami-ina, Nagano 399-45, Japan Search for other works by this author on: Oxford Academic Google Scholar Toshio Mori, Toshio Mori Department of Bioscience and Biotechnology, Faculty of Agriculture, Shinshu University, 8304 Minami-minowa, Kami-ina, Nagano 399-45, Japan Search for other works by this author on: Oxford Academic Google Scholar Motokazu Yoshida, Motokazu Yoshida Department of Bioscience and Biotechnology, Faculty of Agriculture, Shinshu University, 8304 Minami-minowa, Kami-ina, Nagano 399-45, Japan Search for other works by this author on: Oxford Academic Google Scholar Ryozo Iriye Ryozo Iriye Department of Bioscience and Biotechnology, Faculty of Agriculture, Shinshu University, 8304 Minami-minowa, Kami-ina, Nagano 399-45, Japan Search for other works by this author on: Oxford Academic Google Scholar Agricultural and Biological Chemistry, Volume 54, Issue 4, 1 April 1990, Pages 1073–1075, https://doi.org/10.1080/00021369.1990.10870043 Published: 01 April 1990 Article history Received: 09 October 1989 Published: 01 April 1990
An X‐ray undulator beamline PF‐AR‐NW2, which is used for time‐resolved XAFS and/or x‐ray diffraction experiments and also high‐flux XAFS and/or diffraction experiments, has been designed and constructed. The insertion device is an in‐vacuum undulator at a period of 40 mm, and the number of periods is 90 in order to cover an energy range of 5 ∼ 25 keV. Main optical components are a double‐crystal monochromator and a mirror system. The double‐crystal monochromator consists of flat Si (111) crystals, which are cooled by liquid nitrogen. The mirror system consists of focusing and cut‐off mirror systems. The commissioning has been done successfully. The focused beam size with a bent cylindrical mirror is about 0.21 mm × 0.55 mm for vertically and horizontally with the intensity of 6.4 × 1012 photons/s at 12.4 keV. The vertical beam size focused with a bent flat mirror is about 0.06 mm. We compare the performance with the values from a ray‐tracing calculation.
To see the damage of DNA due to ultraviolet-B more distinctly, immunoelectron microscopic studies using a monoclonal antibody against cyclobutane-type thymine dimers were performed. As a result, we could detect the existence of thymine dimers on human genomic DNA and pUC18 plasmid DNA visually. This technique can be useful to locate the photoproducts formed on DNA.
We evaluated the clinical outcomes for ophthalmic endoscope-assisted vitrectomy in consecutive patients with uncomplicated rhegmatogenous retinal detachment (RRD). The primary success rate was 98.4% (125/127) without performing a posterior drainage retinotomy or using perfluorocarbon liquids (PFCL) for subretinal fluid drainage.To investigate the clinical outcomes of endoscope-assisted vitrectomy in patients with uncomplicated RRD.We examined 127 eyes from consecutive patients who underwent repair of RRD by 23- or 25-gauge endoscope-assisted vitrectomy, with a minimum follow-up of 3 months. Eyes with the following criteria were excluded: Giant retinal tears, grade C proliferative vitreoretinopathy, dense vitreous hemorrhage, retinal detachment secondary to other ocular diseases, and prior retinal or vitreous surgery. All cases underwent subretinal fluid drainage, endolaser photocoagulation and fundus inspection were performed under ophthalmic endoscopic observation. Success rate, visual acuity, surgery time and complications were evaluated.Primary and final success rate was 98.4% (125/127) and 100% (127/127), respectively, Surgery time was 59.6±26.3 minutes. The best-corrected visual acuity significantly improved from 20/100 to 20/20 (P<0.0001). There were 2 cases (1.6%) of creation of a peripheral drainage retinotomy and 4 cases (3.1%) of using PFCL to suppress movement of the detached retina, but there were no cases of creation of a posterior drainage retinotomy or using PFCL for subretinal fluid drainage. There was 1 case of presumed endophthalmitis after surgery. There were 12 hypotonous cases at postoperative day 1 and one of them needed additional scleral sutures at postoperative day 4 for prolonged hypotony.The present study demonstrated the efficacy of endoscope-assisted vitrectomy for patients with uncomplicated RRD. To perform endoscope-assisted vitrectomy safely, sufficient closure of sclerotomies is necessary at the end of surgery.
The modifying effects of three kinds of fat (corn oil, beef tallow or perilla oil, each at 20% in the diet) on F344 rat prostate carcinogenesis induced by 3,2‐dimethyl‐4‐aminobiphenyl (DMAB) were investigated. Non‐invasive carcinomas of the ventral prostate were induced by DMAB alone and invasive carcinomas of the other prostate lobes and seminal vesicles by DMAB and testosterone propionate (TP). Eight groups of F344 rats were initiated with 50 mg/kg body weight of DMAB at 2‐week intervals for the first 20 weeks, four also receiving TP, extended until week 60. The animals received basal chow powder diet or one of three high fat diets throughout the experiment (60 weeks). One further group served as a non‐carcinogen‐treated control maintained on basal chow powder diet. Beef tallow significantly increased the development of ventral prostate carcinomas with DMAB alone (from 15 to 45%, P<0.05), while perilla oil reduced the incidence of prostatic intraepithelial neoplasia (PIN) in the ventral lobe of rats given DMAB + TP (from 70 to 10%, P<0.01), but not in those given DMAB alone. No other effects of high fats were observed regarding PIN or invasive cancers of the dorsolateral and anterior prostate or seminal vesicles. A satellite experiment demonstrated that all high fat diets for 4 weeks increased the 5‐bromo‐2‐deoxyuridine (BrdU) labeling index of prostate epithelial cells, suggesting that a high fat intake, irrespective of the fatty acid composition, may accelerate cell kinetics in the prostate. Of the three high fat diets, beef tallow was also found to increase intestinal carcinogenesis. Thus, the present data revealed carcinogenesis in the prostate and intestine to be promoted by beef tallow.
Prevention of medication-related osteonecrosis of the jaw (MRONJ) in patients with osteoporosis requires the cooperation of physicians and dentists. We investigated the knowledge, experience, and behaviour related to medical and dental cooperation for MRONJ prevention in patients with osteoporosis between physicians and dentists practising in the Shiga prefecture.We conducted a cross-sectional study to investigate the cooperation between practising physicians and dentists for preventing osteonecrosis of the jaw (ONJ) in patients with osteoporosis using 2 separate questionnaires from July 28, 2018, to February 3, 2019.Of 461 dentists who were sent the questionnaires at their dental clinics, 307 (67%) responded via fax. Of 846 physicians who were sent the questionnaire at their clinics, 378 (45%) responded via fax. Of these, 268 (32%) were finally analysed because 110 (13%) physicians had never treated patients with osteoporosis; 50% dentists and 24% physicians were familiar with the MRONJ position paper in Japan, and 39% dentists and 9% physicians had encountered MRONJ in their clinical practice. A total of 30% physicians had requested oral health care by a dentist before administering bone-modifying agents (BMA) therapy. The knowledge and experience of MRONJ differed between physicians and dentists.The behaviour of physicians and dentists was insufficient to enable medical and dental cooperation for the prevention of MRONJ in patients with osteoporosis. The lack of cooperation between physicians and dentists during osteoporosis treatment in the Shiga prefecture in Japan is documented in this study.
