Survival of Bacteriophage T4 in Quasi-Pure Ionic Solutions

The preservative qualities of individual ionic compounds impacting the infectivity of T4 virions were elucidated. T4 virions were immersed in quasi-pure ionic solutions prior to the adsorption process, and the plaque forming unit (pfu) values of these were measured following the conventional method. In neutral ionic solutions, the minimum and the optimum concentrations of preservative qualities corresponded with the results obtained from the multi-ionic media/buffers. In acid and alkali solutions, phages show tolerances at a pH range of 5-11 in multi-ionic media/buffers. T4 virions show no tolerance in quasi-pure acid, neutral, and weak alkaline conditions. The preservative quality of T4 virions increased in over 10-1 mM OH- solution, equivalent to a pH value over 10, which corresponds to the pKa of the deprotonation of the DNA bases G and T. Infectivity was lost below 10-1 mM OH- and higher than 10 mM OH-. These results imply that maintaining infectivity of a virion may need the flexibility of the intra-capsid DNA by deprotonation.

Radiation therapy with concurrent retrograde superselective intra-arterial chemotherapy for gingival carcinoma

PURPOSE

The aim of this study was to review the efficacy and toxicity of radiation therapy with concurrent retrograde superselective intra-arterial chemotherapy in the treatment of gingival carcinoma.

METHODS AND MATERIALS

In all, 34 patients (21 men and 13 women) with squamous cell carcinoma of the gingiva underwent radiation therapy with concurrent retrograde superselective intra-arterial chemotherapy. Treatment consisted of daily external irradiation and concurrent retrograde superselective intra-arterial infusion with cisplatin and docetaxel. A median total dose of 60 Gy in 30 fractions was delivered to tumors.

RESULTS

Of the 34 patients, 29 (85 %) achieved a complete response (CR) and 5 had residual tumors. Of the 29 patients with a CR, 2 had local recurrences and 1 had distant metastasis 1-15 months after treatment. Twenty-six of the 36 patients had survived at a median follow-up time of 36 months (range 12-79 months); 4 died of cancer and 4 died of non-cancer-related causes. At both 3 and 5 years after treatment, the overall survival rates were 79 % and the cause-specific survival rates were 85 %. Osteoradionecrosis of the mandibular bone only developed in 1 patient after treatment.

CONCLUSION

Radiation therapy with concurrent retrograde superselective intra-arterial chemotherapy was effective and safe in the treatment of gingival carcinoma. This treatment may be a promising curative and organ-preserving treatment option for gingival carcinoma.

Particle counter determination of bacterial biomass in seawater

The applicability of the Elzone particle counter to the determination of marine bacterial biomass was investigated. The biomass of bacterial pure cultures and a mixed natural population were followed by using the particle counter, a CHN analyzer, and an ATP analyzer. The particle counter showed the precise size distribution of number and volume of submicron-size particles in seawater. For the pure cultured bacterial strains, the conversion factor from volume to carbon is 0.209 mg of C per mm, and for natural bacterial cells of >0.6 mum in diameter, it is 0.184 mg of C per mm. It is recommended that 0.2 be used as the conversion factor for both pure cultured marine bacterial cells and natural bacteria from coastal and near-shore marine environments.

Physical and topographic factors affecting suspended particulate matter composition in a shallow tropical estuary

To better understand topography-dependent characteristics of suspended particulate matter (SPM) in a tropical shallow estuary during dry season, the physical factors causing an increase in SPM and the sources of SPM were investigated at the western coast of Thailand. Single and multiple regression analyses using physical parameters as independent variables indicated that periodic tidal current-driven resuspension, episodic wind-driven resuspension, and river-borne inputs were the most important factors controlling SPM increases in areas surrounded by sand bars, areas directly facing the ocean, and areas close to the river mouth, respectively. The assessment of the origin of increased SPM over the background levels estimated from the chemical signatures (delta(13)C and C/N ratio) at all investigated locations and for each event responsible for an increase in SPM confirmed the results of the multiple regression analyses. The results suggested that specific characteristics of SPM at each location were highly contributed by sedimentary materials and could be rather consistent through the season under similar weather conditions.

Validity of positron emission tomography using fluoro-2-deoxyglucose for the preoperative evaluation of endometrial cancer

To clarify the validity of positron emission tomography using fluoro-2-deoxyglucose (FDG-PET) for the preoperative evaluation of endometrial cancer, we analyzed the preoperative FDG-PET images of both primary and metastatic lesions of 30 patients with endometrial cancer, and compared them with computed tomography (CT) and/or magnetic resonance imaging (MRI) images and the results of postoperative pathologic findings. As to the primary lesions, FDG-PET could easily identify the cancer, and the sensitivity was 96.7%, which tended to be higher than that of 83.3% by CT/MRI. As to the evaluation of retroperitoneal lymph node metastasis, FDG-PET could detect none of five cases of lymph node metastatic lesions of up to 0.6 cm in diameter but had higher specificity (100%) compared with CT/MRI (85.7%). The sensitivity of FDG-PET for detection of extrauterine lesions excluding retroperitoneal lymph nodes was 83.3% and was superior to that of CT/MRI (66.7%), although there was no difference in the specificity between the modalities (100%). The diagnostic ability of FDG-PET was limited if used alone, but FDG-PET gave additional information especially with regard to the extrauterine lesions whose significance could not be determined on CT/MRI. However, we also found that FDG-PET could not identify any lymph node metastasis less than 1 cm in diameter; therefore, a negative finding of lymph node metastasis on FDG-PET should not be interpreted as a reason for omitting retroperitoneal lymph node dissection for the precise surgical staging of endometrial cancer.

Structural significances of pseudouridination and methylation of uridine residues in tRNA: X-ray analyses of DNA dodecamers containing uridine and pseudouridine

Pseudouridine (psi) and 5-methyluridine (T) residues found in tRNA are prepared through modification of the uridine residues by specific enzymes just after transcription. On the other hands, thymidine residues in DNA are incorporated using dTTP which is derived from UTP before replication. In order to investigate the necessity of such modification and the structural properties of these residues, we have determined two X-ray structures of DNA dodecamers containing dU or d psi, and compared with that containing dT. There is found remarkable difference in arrangement of water molecules hydrogen-bonded to these residues, which form a Watson-Crick type base pair. The psi residue stabilizes the phosphate-backbone conformation of the phosphate group via water mediated hydrogen bond networks, while dT residues seem to prevent from attacking of water molecules.

Production of refractory dissolved organic matter by bacteria

Most of the oceanic reservoir of dissolved organic matter (DOM) is of marine origin and is resistant to microbial oxidation, but little is known about the mechanisms of its formation. In a laboratory study, natural assemblages of marine bacteria rapidly (in <48 hours) utilized labile compounds (glucose, glutamate) and produced refractory DOM that persisted for more than a year. Only 10 to 15% of the bacterially derived DOM was identified as hydrolyzable amino acids and sugars, a feature consistent with marine DOM. These results suggest that microbial processes alter the molecular structure of DOM, making it resistant to further degradation and thereby preserving fixed carbon in the ocean.

Abundance of Viruses in Marine Waters: Assessment by Epifluorescence and Transmission Electron Microscopy

Abundance of bacteria and tiny DNA-associated particles in the upper layer of Japanese coastal and offshore waters was evaluated by epifluorescence microscopy with 0.015-μm-pore-size Nuclepore filters. The number of tiny DNA-associated particles was compared with the abundance of virus particles estimated by transmission electron microscopy. Although a large variation in virus abundance (1.2 � 10 6 to 35 � 10 6 ml −1 ) was obtained with the transmission electron microscopy method, the ratio of 4′,6-diamidino-2-phenylindole-reactive tiny particles to viruses was in a rather narrow range (1.0 to 1.6), indicating that the majority of the tiny DNA-associated particles identified by epifluorescence microscopy were actually virus particles. This result implies the possibility of using epifluorescence microscopy for the evaluation of virus abundance in marine environments.

Micromolar sulfide concentrations alleviate acetylene blockage of nitrous oxide reduction by denitrifying Pseudomonas fluorescens

The influence of low sulfide concentrations on nitrous oxide (N2O) reduction by resting cells of denitrifying Pseudomonas fluorescens was studied. Nitrous oxide reduction was inhibited by sulfide with an apparent Ki value of 1 μM. The inhibition was immediate and was readily alleviated by a short treatment of the cells with O2. In the absence of sulfide, addition of acetylene (0.2 kPa C2H2 or more) caused an immediate and complete inhibition of N2O reduction. However, when the sulfide concentration was higher than 2 μM, addition of C2H2 (range of 0.7–13 kPa tested) gave incomplete inhibition of the N2O reduction. Complete inhibition was in this case only obtained after prolonged exposure to the C2H2. The transition period with incomplete C2H2 blockage was shortest (about 20 min) for relatively high C2H2 applications (about 10 kPa). Incomplete C2H2 blockage was seen only when sulfide was added to the cell suspensions before C2H2. The data may relate to the low efficacy of the "acetylene blockage technique" when the assay is applied to [Formula: see text]-deficient and reducing environments.

Estimates of Denitrification and Nitrification in Coastal and Estuarine Sediments

Denitrification and nitrification in sediments of Tama Estuary and Odawa Bay, Japan, were investigated by the combined use of a continuous-flow sediment-water system and a 15 N tracer technique. At Odawa Bay, the nitrification rate was comparable to the nitrate reduction rate, and 70% of the N 2 evolved originated from nitrogenous oxides (nitrate and nitrite) which were produced by the action of nitrifying bacteria in the sediments. At Tama Estuary, the nitrate reduction rate was 11 to 17 times higher than the nitrification rate, and nitrogenous oxides derived from ammonium accounted for only 6 to 9% of the N 2 evolution by denitrification.

Denitrification, Nitrate Reduction, and Oxygen Consumption in Coastal and Estuarine Sediments

Denitrification and consumption of oxygen and nitrate in sediments from Tama Estuary, Odawa Bay, and Tokyo Bay were measured in an experimental sediment-water system. Filtered seawater containing [ 15 N]nitrate flowed continuously over undisturbed sediments, and the concentrations of O 2 , nitrate, and nitrite in the influent and effluent and of 15 N 2 in the effluent were monitored. Under steady-state conditions, the rate of nitrate consumption was the same order of magnitude as the rate of oxygen consumption in Tama Estuary sediments, whereas the former rate was one order of magnitude lower than the latter rate in Odawa Bay and Tokyo Bay sediments. Denitrification accounted for 27 to 57% of the nitrate consumption.

Simultaneous determinations of nitrification and nitrate reduction in coastal sediments by a 15N dilution technique

Nitrification, the oxidation of ammonia to nitrite and nitrate, and nitrate reduction by bacteria in coastal sediments of Mangoku-Ura and Odawa Bay were simultaneously determined by a 15N dilution technique. In muddy sediments of Mangoku-Ura, nitrate reduction proceeded at a rate of 10(-2) to 10 X 10(-2) microgram-atoms of N/g per h. Nitrification was far less intensive. Denitrification, or N2 production from nitrate, accounted for about 30% of the nitrate reduction. A simultaneous occurrence of nitrification and nitrate reduction with a similar rate of 10(-2) microgram-atoms of N/g per h was demonstrated in sandy sediment collected from a Zostera bed of Odawa Bay.

Denitrification and Ammonia Formation in Anaerobic Coastal Sediments

Simultaneous determinations of nitrogen gas production, ammonia, and particulate organic nitrogen formation in the coastal sediments of Mangoku-Ura, Simoda Bay, and Tokyo Bay were made by using the 15 N-label tracer method. The rate of nitrogen gas production in the sediment surface layer was about 10 −2 μg atom of N per g per h, irrespective of the location of the sediments examined. [ 15 N]ammonia and -particulate organic nitrogen accounted for 20 to 70% of the three products, and after several hours of incubation, the major fraction of nondenitrified 15 N in Mangoku-Ura and Simoda Bay sediments was recovered as ammonia. In Tokyo Bay sediments, particulate organic nitrogen was produced at a greater rate than was ammonia. The reduction rate data suggest that the pathway of nitrate reduction to ammonia is important in coastal sediments.

Growth yield of a denitrifying bacterium, Pseudomonas denitrificans, under aerobic and denitrifying conditions

The effciency of denitrification, or anaerobic respiration, in Pseudomonas denitrificans was investigated, using growth yield as an index. Glutamate was mainly used as the sole source of energy and carbon. In batch culture, the growth yield per mole of electrons transported through the respiratory system under denitrifying conditions was about half that under aerobic conditions. Similar figures were also obtained in chemostat cultures under glutamate-limited conditions. The decrease in growth yield under denitrifying conditions could be due to the restriction of phosphorylation associated with nitrate reduction to nitrogen gas.

Energy yield of denitrification: an estimate from growth yield in continuous cultures of Pseudomonas denitrificans under nitrate-, nitrite- and oxide-limited conditions

The molar growth yields of Pseudomonas denitrificans, for nitrate, nitrite and nitrous oxide, were determined in chemostat culture under electron acceptor-limited conditions. Glutamate was used as the source of energy, carbon and nitrogen. The catabolic pattern was identical, irrespective of the terminal electron acceptors. The molar growth yields, corrected for maintenance energy, were 28-6 g/mol nitrate, 16-9 g/mol nitrite and 8-8 g/mol nitrous oxide. The energy yield, expressed on an electron basis, was proportional to the oxidation number of the nitrogen: nitrate (plus 5), nitrite (plus 3) and nitrous oxide (plus 1). It was concluded that oxidative phosphorylation occurs to a similar extent in each of the electron transport chains associated with the reduction of nitrate to nitrite, nitrite to nitrous oxide and nitrous oxide to nitrogen.