Methanol Oxidation at Platinum in Alkaline Media: A Study of the Effects of Hydroxide Concentration and of Mass Transport.

The hydroxide ion concentration dependence of the methanol oxidation reaction at Pt was studied using microelectrode voltammetry and rotating disk electrode voltammetry. Both methods suggest that the rate of methanol oxidation is limited by hydroxide mass transport at low hydroxide concentrations, while it is inhibited by hydroxide adsorption at high concentrations. It was possible to shift from the transport-limited regime to the inhibitory regime by varying the bulk concentration of hydroxide or by varying mass transport to the electrode. Rotating ring-disk electrode voltammetry was employed to qualitatively assess changes in the diffusion layer pH. The results indicated a decrease in the surface pH during methanol oxidation, as expected, but also that the pH reached a steady state during hydroxide transport limited methanol oxidation.

A modified sol-gel technique for pore size control in porous aluminum oxide nanowire templates.

A modified sol-gel technique was developed to continuously vary the pore diameters in porous alumina templates for the purpose of growing nanowires. To coat the pore walls, the porous alumina film is initially soaked in a methanol/water solution to fill the pores with the desired concentration of water. The porous alumina film is then exposed to a solution of 3-aminopropyltriethoxysilane (APTES) in toluene, creating a surface layer of APTES. The concentration of water in the pores correlates with the thickness of the APTES polymer coating that is obtained. This approach exerts greater control over the extent of silane polymerization than traditional sol-gel reactions by limiting the amount of water present for reaction. Factors such as the APTES concentration, exposure time, and organic cosolvent choice did not influence the coating thickness. However, the density and thickness of the APTES coating can be manipulated by varying the pH of the methanol/water solution as well as post-treatment annealing. Further modification of the pore size was achieved by subsequent reaction of the APTES coating with poly(methyl methacrylate) (PMMA). The PMMA couples to amine groups on the APTES polymer surface by an aminolysis reaction. Bismuth telluride nanowires were electrodeposited in the polymer-coated porous alumina templates using previously established methods. Nanowire diameters were smaller when the nanowires were prepared in modified templates as anticipated.

No evidence of increased mutation rates at microsatellite loci in offspring of A-bomb survivors.

To evaluate the genetic effects of A-bomb radiation, we examined mutations at 40 microsatellite loci in exposed families (father-mother-offspring, mostly uni-parental exposures), which consisted of 66 offspring having a mean paternal dose of 1.87 Gy and a mean maternal dose of 1.27 Gy. The control families consisted of 63 offspring whose parents either were exposed to low doses of radiation (< 0.01 Gy) or were not in the cities of Hiroshima or Nagasaki at the time of the bombs. We found seven mutations in the exposed alleles (7/2,789; mutation rate 0.25 x 10(-2)/locus/generation) and 26 in the unexposed alleles (26/7,465; 0.35 x 10(-2)/locus/generation), which does not indicate an effect from parental exposure to radiation. Although we could not assign the parental origins of four mutations, the conclusion may hold since even if we assume that these four mutations had occurred in the exposed alleles, the estimated mean mutation rate would be 0.39 x 10(-2) in the exposed group [(7 + 4)/2,789)], which is slightly higher than 0.35 x 10(-2) in the control group, but the difference is not statistically significant.

Critical role of RecA and RecF proteins in strand break rejoining and maintenance of fidelity of rejoining following gamma-radiation-induced damage to pMTa4 DNA in E. coli.

PURPOSE: This study was undertaken to understand the roles of RecA and RecF proteins in strand break rejoining and maintenance of fidelity of the process following exposure of E. coli to gamma-radiation in vivo. MATERIALS AND METHODS: A plasmid DNA construct, pMTa4, was transformed into isogenic repair proficient (wild) and deficient (recF and recA) E. coli strains and gamma-irradiated up to 30 Gy in vivo. The plasmid DNA was isolated under repair non-permissive (R-)and permissive (R+) conditions and analyzed by gel electrophoresis for the yields of single strand breaks (SSB) and double strand breaks (DSB) and their repair. The clonogenic survival of the E. coli was also recorded. The effects of gamma-irradiation on recA reconstituted with cell free extract of wild strain or ultra-violet (UV)-irradiation were also monitored. RESULTS: None of the strains used in this investigation showed effects of radiation-induced oxidative base damage. The dose dependent increase in SSB and DSB on pMTa4 in wild and recF mutants in R- condition were abolished upon repair incubation. The recA mutant exhibited a disturbed yield of SSB and DSB along with formation of gamma-radiation-induced 'ladder'. The 'ladder' was not observed after repair incubation, UV-irradiation or gamma-irradiation in presence of cell-free extract of wild strain. The survival of recA mutants was seriously compromised. CONCLUSIONS: Wild, recF and recA strains of E. coli could repair gamma-irradiation-induced oxidative damage to base or nucleotide (NT) in vivo. In absence of either RecA or RecF proteins, efficiency of rejoining of strand went down; RecA proteins seemed more critical than RecF in this. High fidelity or correct rejoining of strand breaks, on the other hand, seemed to require simultaneous presence of both RecA and RecF proteins.

Transgenerational transmission of radiation- and chemically induced tumors and congenital anomalies in mice: studies of their possible relationship to induced chromosomal and molecular changes.

This article provides a broad overview of our earlier studies on the induction of tumors and congenital anomalies in the progeny of X-irradiated or chemically treated mice and our subsequent (published, hitherto unpublished and on-going) investigations aimed at identifying potential relationships between genetic changes induced in germ cells and the adverse effects manifest as tumors and congenital anomalies using cytogenetic and molecular approaches. The earlier studies document the fact that tumors and congenital anomalies can be induced by irradiation or treatment with certain chemicals such as urethane and that these phenotypes are heritable i.e., transmitted to generations beyond the first generation. These findings support the view that transmissible induced genetic changes are involved. The induced rates of congenital abnormalities and tumors are about two orders of magnitude higher than those recorded in the literature from classical mutation studies with specific locus mutations. The cytogenetic studies addressed the question of whether there were any relationships between induced translocations and induced tumors. The available data permit the inference that gross chromosomal changes may not be involved but do not exclude smaller induced genetic changes that are beyond the resolution of the techniques used in these studies. Other work on possible relationship between visible chromosomal anomalies (in bone marrow preparations) and tumors were likewise negative. However, there were indications that some induced cytogenetic changes might underlie induced congenital anomalies, i.e., trisomies, deletions and inversions were observed in induced and transmissible congenital anomalies (such as dwarfs, tail anomalies). Studies that explored possible relationships between induction of minisatellite mutations at the Pc-3 locus and tumors were negative. However, gene expression analysis of tumor (hepatoma)-susceptible offspring of progeny descended from irradiated male mice showed abnormal expression of many genes. Of these, only very few were oncogenes. This lends some support to our hypothesis that cumulative changes in gene expression of many genes, which perform normal cellular functions, may contribute to the occurrence of tumors in the offspring of irradiated or chemically treated mice.

[A case report of pulmonary nocardiosis successfully treated with a combination of sulfamethoxazole-trimethoprim (ST) and sparfloxacin].

We encountered a case of pulmonary nocardiosis that responded dramatically to combined ST and sparfloxacin treatment. A 55-year-old woman presented with fever, cough and yellowish sputum. She had been under treatment with oral prednisolone (15 mg per day) since July 1997 after a diagnosis of Evans syndrome. A high fever of 39.8 degrees C was noted on January 30, 1998. The patient was hospitalized for bloody sputum, bilateral hypochondriac pain and evidence of infiltrative opacities in the left lower lobe on chest radiography. Bacterial pneumonia was suspected, and she was treated with piperacillin, but her clinical symptoms did not improve. Sputum culture and serologic examination failed to lead to a definitive diagnosis. Nocardia farcinica was isolated by culturing tissue obtained by CT-guided transcutaneous pulmonary biopsy, leading to a diagnosis of pulmonary nocardiosis. The results of an MIC test for antimicrobial agents led to treatment with a combination of ST and sparfloxacin, and the clinical symptoms improved. These clinical observations suggest that, when pneumonia is diagnosed in patients who have been receiving oral steroids for a prolonged period, pulmonary nocardiosis should be considered in the differential diagnosis to enable selection of appropriate antimicrobial agents.

Cloning and characterization of Dfak56, a homolog of focal adhesion kinase, in Drosophila melanogaster.

The focal adhesion kinase (FAK) protein-tyrosine kinase plays important roles in cell adhesion in vertebrates. Using polymerase chain reaction-based cloning strategy, we cloned a Drosophila gene that is homologous to the vertebrate FAK family of protein-tyrosine kinases. We designated this gene Dfak56 and characterized its gene product. The overall protein structure and deduced amino acid sequence of Dfak56 show significant similarity to those of FAK and PYK2. Dfak56 has in vitro autophosphorylation activity at tyrosine residues. Expression of the Dfak56 mRNA and the protein was observed in the central nervous system and the muscle-epidermis attachment site in the embryo, where Drosophila position-specific integrins are localized. The results suggest that like FAK in vertebrates, Dfak56 functions downstream of integrins. Dfak56 was tyrosine-phosphorylated upon integrin-dependent attachment of the cell to the extracellular matrix. We conclude that the Dfak56 tyrosine kinase is involved in integrin-mediated cell adhesion signaling and thus is a functional homolog of vertebrate FAK.

DCRY is a Drosophila photoreceptor protein implicated in light entrainment of circadian rhythm.

BACKGROUND: Light is the major environmental signal for the entrainment of circadian rhythms. In Drosophila melanogaster, the period(per) and timeless (tim) genes are required for circadian behavioural rhythms and their expression levels undergo circadian fluctuations. Light signals can entrain these rhythms by shifting their phases. However, little is known about the molecular mechanism for the perception and transduction of the light signal. The members of the photolyase/cryptochrome family contain flavin adenine dinucleotide (FAD) as chromophore and are involved in two diverse functions, DNA repair and photoreception of environmental light signals. RESULTS: We report the cloning of a new member of this family, dcry, from Drosophila. Northern blot analysis shows that this gene is expressed in various tissues. The dcry mRNA is expressed in a circadian manner in adult heads, while such rhythmic fluctuation is abolished in the clock-defective per0 and tim0 mutants. The circadian expression is dampened down in constant darkness. The over-expression of the dcry gene alters the light-induced phase delay in the locomotor activity rhythms of flies. CONCLUSION: These results suggest that DCRY is a circadian photoreceptor and that its expression is regulated by circadian clock genes.

Portal imaging by intravenous three-dimensional computed tomography after pancreaticoduodenectomy: a report of four cases.

By employing three-dimensional computed tomography (CT) for portography, we analyzed the portal vein changes during the initial stage after a pancreaticoduodenectomy (PD), which seemed to affect postoperative complications. Four patients underwent PD without portal vein reconstruction with a standard radical lymph node dissection for cancer of the pancreaticoduodenal area. A total of 140 ml of contrast medium was intravenously injected at 2.5 ml/s, and imaging was started after 65s with a Hitachi W-2000 CT scanner. Three-dimensional portal vein images were then reconstructed by the Voxel Transmission method. Three-dimensional CT showed portal stenosis in our all patients from the first to the third week after PD. In three of the patients, stenosis disappeared by week 7, 8, or 15, respectively, without the formation of a bypass. In three patients, portal vein stenosis was severe while in one patient, it was mild. Severe complications such as gastrointestinal hemorrhaging and hepatic abscess occurred in two patients with severe portal stenosis. The onset of portal stenosis might therefore affect postoperative complications after PD.

[Bone metastasis of primary lung cancer].

To improve the treatment of patients with bone metastasis from lung cancer, 178 (23.8%) of 748 patients with primary lung cancer admitted to our hospital during an 11-year period were studied. The 178 patients were mainly women. The frequency of bone metastasis was significantly higher among patients with adenocarcinoma than among those with small cell or squamous cell cancer. The concentration of carcinoembryonic antigen in serum was significantly higher in patients with bone metastasis than in those with stage IV lung cancer without bone metastasis. The bone lesions were symptomatic in 116 patients (65%) and were treated in 67. Symptomatic improvement was achieved in 50 patients (74%) and pain was alleviated in 94%. However, neurological disorders improved in only 41%. Differences in survival did not depend on the presence or absence of symptomatic bone metastasis or no whether the metastases were treated. The median survival time of patients who responded to treatment tended to be longer than that of patients in whom treatment was not effective. The median survival time calculated from the start of treatment was 5 months for patients with bone metastasis and 7.3 months for patients with stage IV disease without bone metastasis. Aggressive local treatment may be effective for painful bone metastasis.

A new Drosophila ultraviolet light-damaged DNA recognition endonuclease that selectively nicks a (6-4) photoproduct site.

We have previously described the purification of an ultraviolet light (UV) damage-specific DNA-binding protein from Drosophila melanogaster, designated D-DDB P1 [Nucleic Acids Res., 23 (1995) 2600-2607]. Here, we obtained highly purified D-DDB P1 from Drosophila Kc cells, and we found that D-DDB P1 is also a nuclease. D-DDB P1 can selectively bind to pyrimidine (6-4) pyrimidone photoproducts, and in the presence of Mg++, D-DDB P1 can catalyze an incision immediately on the 3' and 5' sides of the (6-4) photoproduct site.

[Rheumatoid nodule diagnosed by thoracoscopy using flexible fiberoptic bronchoscope].

A 51-year-old man had been treated at a nearby hospital since 1993 for rheumatoid arthritis. Right pectoralgia developed in December 1994, and the patient consulted a nearby hospital, which detected right pleural effusion retention was pointed out on chest x-ray films. The patient was referred and admitted to our hospital. Rheumatic pleurisy was suspected because of a high serum rheumatoid factor(RF)level and high RF and high rheumatoid arthritis hemagglutination levels in the pleural effusion. However, due to a high adenosine deaminase level in the pleural effusion tuberculous pleurisy could not be ruled out. After drainage through a trocar catheter, the thoracic cavity was examined by thoracoscopy through the site of catheter insertion. As a result, sporadic bluish white nodular lesions were observed on the pleura. Granuloma formations presenting a palisade arrangement of giant cells were also observed, and pathologically diagnosed as rheumatoid nodules, thus providing the basis for a diagnosis of rheumatic pleurisy. Treatment with an increased dose of prednisolone achieved a rapid remission of the pleural effusion. Our experience underscored the usefulness of thoracoscopy as a means diagnosing of rheumatic pleurisy.

Molecular evolution of the photolyase-blue-light photoreceptor family.

The photolyase-blue-light photoreceptor family is composed of cyclobutane pyrimidine dimer (CPD) photolyases, (6-4) photolyases, and blue-light photoreceptors. CPD photolyase and (6-4) photolyase are involved in photoreactivation for CPD and (6-4) photoproducts, respectively. CPD photolyase is classified into two subclasses, class I and II, based on amino acid sequence similarity. Blue-light photoreceptors are essential light detectors for the early development of plants. The amino acid sequence of the receptor is similar to those of the photolyases, although the receptor does not show the activity of photoreactivation. To investigate the functional divergence of the family, the amino acid sequences of the proteins were aligned. The alignment suggested that the recognition mechanisms of the cofactors and the substrate of class I CPD photolyases (class I photolyases) are different from those of class II CPD photolyases (class II photolyases). We reconstructed the phylogenetic trees based on the alignment by the NJ method and the ML method. The phylogenetic analysis suggested that the ancestral gene of the family had encoded CPD photolyase and that the gene duplication of the ancestral proteins had occurred at least eight times before the divergence between eubacteria and eukaryotes.

Mutations induced in Drosophila during space flight.

To examine the possible effects of space radiation on living organisms, fruit flies Drosophila melanogaster were loaded on the US Space Shuttle Endeavour, and after the flight we have analyzed two types of mutations, sex-linked recessive lethal mutations induced in male reproductive cells and somatic mutations which give rise to morphological changes in hairs growing on the surface of wing epidermal cells. Wild type strains and a radiation-sensitive strain mei-41 were used. The frequencies of sex-linked recessive lethal mutations in flight groups were 2 and 3 times higher for wild type Canton-S and mei-41 strains, respectively, than those in ground control groups. By contrast, the frequencies of wing-hair somatic mutations differed little between flight and control groups. The possibility that the space environment causes mutations in certain types of cells such as male reproductive cells, is discussed.

Non-mutagenic repair of (6-4)photoproducts by (6-4)photolyase purified from Drosophila melanogaster.

The (6-4)photoproduct DNA photolyase ((6-4)photolyase) repairs UV-induced pyrimidine (6-4) pyrimidone photoproduct ((6-4)photoproduct, pyr[6,4]pyr) in a light dependent manner. Drosophila (6-4)photolyase was purified to near homogeneity from Drosophila embryonic cells and is shown to be a 62 kDa protein as determined by sodium dodecyl sulfate-polyacrylamide gel electrophoresis. The purified (6-4)photolyase repairs (6-4)photoproducts induced at 5'-CC-3' site (C[6,4]C) as well as T[6,4]T and T[6,4]C. Photoreactivation of (6-4)photoproduct constructed in M13 phage eliminates the replication block and abolishes induced mutagenesis in E. coli cells, suggesting that the (6-4)photolyase repairs the photoproduct to the unmodified form.

[Gastrointestinal metastasis from lung cancer].

Metastasis of lung cancer to the digestive tract (excluding the esophagus) was confirmed by surgery or autopsy in 30 of the 1635 lung-cancer patients admitted to this Center during the 17-year period since 1977. The diagnosis was made before death in 7 and after death in 23. Metastasis of large cell carcinoma was the most common (3.7%), followed by adenocarcinoma (2.4%), small cell carcinoma (1.7%), and squamous cell carcinoma (0.7%). Metastasis to the stomach occurred in 0.4%, to the small intestine in 1.1% and to the colon in 0.5%. The overall percentage of metastasis to the digestive tract was 1.8%. Among the 298 cases diagnosed at autopsy, metastasis to the digestive tract occurred in 9.7%; stomach, 2.6%; small intestine, 5.7%; and colon, 3.0%. Eleven of the patients in whom the diagnosis was made at autopsy had abdominal symptoms while they were alive. In 11 cases diagnosed at autopsy, occult blood was positive in 9, but 6 of those 9 patients were asymptomatic. The occult-blood test is considered to be helpful as a supplementary diagnostic method in detecting metastasis of lung cancer to the digestive tract. Among the cases diagnosed while the patients were alive, metastasis was observed in the small intestine in 6 and in the colon in 1. The major manifestations were melena, ileus, intussusception, and perforation; 4 patients required emergency surgery. The prognosis was poor: the mean survival period from the onset of symptoms was 49 days. The direct cause of death was metastasis to the digestive tract in 5 cases. The possibility of metastasis to the digestive tract is high when progressive abdominal symptoms are observed and the stool is persistently positive on occult-blood tests.

Purification and characterization of Drosophila melanogaster photolyase.

Animal-type photolyases have very limited sequence homology to microbial-type photolyases. We wanted to find out whether the two types of enzymes have different or similar biochemical and photochemical properties. In particular, the chromophore/cofactor composition of animal photolyases is of special interest since the presence and nature of a second chromophore in these enzymes are not known in contrast to the microbial photolyases which contain FAD cofactor, and folate or deazaflavin as second chromophores. We overproduced the Drosophila melanogaster photolyase in Escherichia coli using the cloned gene. The enzyme contains FAD and folate and thus belongs in the folate class of enzymes but with an action spectrum peak at 420 nm.

Similarity among the Drosophila (6-4)photolyase, a human photolyase homolog, and the DNA photolyase-blue-light photoreceptor family.

Ultraviolet light (UV)-induced DNA damage can be repaired by DNA photolyase in a light-dependent manner. Two types of photolyase are known, one specific for cyclobutane pyrimidine dimers (CPD photolyase) and another specific for pyrimidine (6-4) pyrimidone photoproducts[(6-4)photolyase]. In contrast to the CPD photolyase, which has been detected in a wide variety of organisms, the (6-4)photolyase has been found only in Drosophila melanogaster. In the present study a gene encoding the Drosophila(6-4)photolyase ws cloned, and the deduced amino acid sequence of the product was found to be similar to the CPD photolyase and to the blue-light photoreceptor of plants. A homolog of the Drosophila (6-4)photolyase gene was also cloned from human cells.

DNA-damaging potency and genotoxicity of aflatoxin M1 in somatic cells in vivo of Drosophila melanogaster.

Aflatoxin M1 (AFM1), a metabolic hydroxylation product of aflatoxin B1 (AFB1), and the parent compound were comparatively assayed for DNA-damaging potency and genotoxicity in vivo in Drosophila melanogaster using, respectively, the mei-9a mei-41D5 DNA repair test and the mwh/flr3 wing spot test. In the repair test, larval stock, consisting of meiotic recombination-deficient double mutant mei-9a mei-41D5 males and repair-proficient females, was exposed to the test agents, and the preferential killing of the mutant larvae was taken as evidence of the DNA-damaging effect. In this test, AFM1 was registered as a DNA-damaging agent with an activity approximately 3-fold lower than that of AFB1. In the wing spot test, where larval flies, trans-heterozygous for the somatic cell markers mwh and flr3, were treated and the wings were inspected at adulthood for spots manifesting the phenotypes of the markers, AFM1 exerted a genotoxic effect compatible to that of AFB1. Based on these results and other data, we predict that AFM1 may be genotoxic in mammalian in-vivo systems as well.