Ammonia and light effect on nitrogenase activity in nitrogen-limited continuous cultures of Rhodopseudomonas capsulata. Role of glutamine synthetase

Nitrogen-limited continuous cultures of Rhodopseudomonas capsulata were used to investigate some aspects of the regulation of nitrogenase activity. The role of glutamine synthetase (GS) in this regulation was examined by measuring changes of its adenylylation state when the light intensity and the nitrogen source were varied. Maximal nitrogenase activity was observed at a dilution rate corresponding to about one third of the maximum specific growth rate (_max), both in ammonia- and in glutamate-limited cultures. At higher dilution rates, both GS and nitrogenase were inactivated by ammonia. Determination of the kinetics of inhibition of both enzymes indicated that the degree of inactivation of nitrogenase and the adenylylation state of GS were not closely related. Increase of light intensity stimulated nitrogenase activity dramatically. Conversely, a shift-down in light intensity to a limiting value resulted in a decrease of nitrogenase activity suggesting that synthesis was inhibited. On the other hand, the adenylylation state of glutamine synthetase appeared to be unaffected by changes in light intensity, indicating that GS is probably not involved in the regulation of nitrogenase expression by light.Abbreviations GS glutamine synthetase - R Rhodopseudomonas - Rs. Rhodospirillum - CTAB cetyltrimethylammonium bromide Dedicated to Prof. Dr. H. G. Schlegel on the occasion of his 60th birthday     

Continuous bioconversion of n-octane to octanoic acid by recombinant Escherichia coli (alk(+)) growing in a two-liquid-phase Chemostat

Escherichia coli is able to grow on sugars in the presence of a bulk n-alkane phase. When E. coli is equipped with the alk genes from Pseudomonas oleovorans, the resulting recombinant strain converts n-alkanes into the corresponding alkanoic acids. To study the effects of growth rate and exposure to a bulk apolar phase on the physiology and the productivity of E. coli, we have grown this microorganism in two-liquid-phase continuous cultures containing 5% (v/v) n-octane.In contrast to batch cultures of wild-tape E. coli grown in the presence of n-octane, cells remained viable during the entire continuous culture, which lasted 200 h. Bioconversion of n-octane to n-octanoic acid by a recombinant E. coli (alk(+)) in a two-liquid-phase continuous culture was made possible by optimizing both the recombinant host strain and the conditions of culturing the organism. Continuous production in such two-phase systems has been maintained for the least 125 h without any changes in the product concentration in the fermentation medium. The volumetric productivity was determined as a function of growth rate and showed a maximum at a dilution rate D = 0.32 h(-1), reaching a continuous production rate of 0.5 g octanoate/L . h (4 tons/m(3) . year). (c) 1993 John Wiley & Sons, Inc.     

连续性血液净化及肠内营养治疗重症胰腺炎疗效及对炎症因子影响

摘要 目的：探究连续血液净化及肠内营养治疗重症胰腺炎患者的疗效及对患者炎症因子水平的影响。方法：选择2018年1月至2019年12月于我院接受治疗的82例重症胰腺炎患者为研究对象,按照治疗方式不同将其分为研究组(49例)与对照组(33例)。对照组患者仅接受连续血液净化,研究组患者在对照组患者基础上加用肠内营养支持,对比两组患者腹痛缓解时间、感染发生率、住院时间、治疗前后血尿素氮(Blood urea nitrogen,BUN)、血肌酐(creatinine,SCr)、C反应蛋白(C-reactive protein,CRP)、白细胞介素-6(interleukin-6,IL-6)、肿瘤坏死因子(tumor necrosis factor,TNF-α)、急性生理与慢性健康评分表评分(acute physiology and chronic health evaluationⅡ,APACHE II)评分的变化。结果：研究组患者腹痛缓解时间、感染发生率、住院时间均短于对照组患者(P<0.05)。治疗后,研究组患者APACHE II评分、血清CRP、IL-6、TNF-α、BUN及SCr水平均低于对照组(P<0.05)。结论：连续血液净化联合肠内营养支持对重症胰腺炎患者具有较好的治疗效果,能够显著加快重症胰腺炎患者转归,改善患者肾损伤及机体炎症状态。     

Measurements of skin surface temperature during mobile phone use

We measured maximum temperature rises on the side of the face after 6 min of continuous mobile phone operation using two models of AMPS analog phones operating in the 835 MHz band and three early model GSM digital phones operating in the 900 MHz band. For the GSM phones the highest recorded temperature rise difference was 2.3 degrees C and for the AMPS phones it was 4.5 degrees C, both at locations on the cheek. The higher differential temperature rise between AMPS and GSM may reflect the higher maximum average operating power of AMPS (600 mW) versus GSM900 (250 mW). Additionally, we compared temperature changes at a consistent location on the cheek for an AMPS phone that was inoperative (-0.7 degrees C), transmitting at full power (+2.6 degrees C) and in stand-by mode (+2.0 degrees C). Our results suggest that direct RF heating of the skin only contributes a small part of the temperature rise and that most is due to heat conduction from the handset.     

絮凝颗粒酵母均匀悬浮体系生长动力学的研究

利用粟酒裂殖酵母(Schizosaccharomyces pombe)变异株自身絮凝形成的颗粒,作为细胞固定化方法。以双酶法制备的淀粉耱化液为底物,在有效容积2．35L的小型悬浮床生物反应器中连续生产酒精。研究了微量供氧条件下该絮凝颗粒酵母均匀悬浮体系的生长动力学,获得了描述其生长规律的模型方程。     

Long-term changes in phytoplankton, zooplankton and salmon related to climate

Recently, large‐scale changes in the biogeography of calanoid copepod crustaceans have been detected in the northeastern North Atlantic Ocean and adjacent seas. Strong biogeographical shifts in all copepod assemblages were found with a northward extension of more than ° in latitude of warm‐water species associated with a decrease in the number of colder‐water species. These changes were attributed to regional increase in sea surface temperature. Here, we have extended these studies to examine long‐term changes in phytoplankton, zooplankton and salmon in relation to hydro‐meteorological forcing in the northeast Atlantic Ocean and adjacent seas. We found highly significant relationships between (1) long‐term changes in all three trophic levels, (2) sea surface temperature in the northeastern Atlantic, (3) Northern Hemisphere temperature and (4) the North Atlantic Oscillation. The similarities detected between plankton, salmon, temperature and hydro‐climatic parameters are also seen in their cyclical variability and in a stepwise shift that started after a pronounced increase in Northern Hemisphere Temperature anomalies at the end of the 1970s. All biological variables show a pronounced change which started after circa 1982 for euphausiids (decline), 1984 for the total abundance of small copepods (increase), 1986 for phytoplankton biomass (increase) and Calanus finmarchicus (decrease) and 1988 for salmon (decrease). This cascade of biological events led to an exceptional period, which is identified after 1986 to present and followed another shift in large‐scale hydro‐climatic variables and sea surface temperature. This regional temperature increase therefore appears to be an important parameter that is at present governing the dynamic equilibrium of northeast Atlantic pelagic ecosystems with possible consequences for biogeochemical processes and fisheries.     

Energy deposition in a model of man in the near field

The spatial distribution of the specific absorption rate (SAR) was measured in a full-scale model of man using implantable electric field probes. The model was exposed in the near-field of linear and aperture antennas at 350 MHz. Effects of the wave polarization, antenna position and antenna gain on the SAR distribution and the average SAR in the whole-body and body parts are reported.     

Impact of light/dark regimen on growth rate,biomass formation and bacteriochlorophyll synthesis in Erythromicrobium hydrolyticum

The impact of illumination on specific growth rate, biomass formation, and synthesis of photopigment was studied in Erythromicrobium hydrolyticum, an obligately aerobic heterotrophic bacterium having the ability to synthesize bacteriochlorophyll a. In dark-grown continuous cultures the concentration of protein increased with increasing dilution rate, the concentration of bacteriochlorophyll a showed the opposite effect. At a dilution rate of 0.08 h^-1 (68% of _max in the dark) and S_R-acetate of 11.8 mM, the concentration of BChla of illuminated cultures in steady-state was 11–22 nM, compared to 230–241 nM in cultures incubated in darkness. No significant differences were observed in the concentration of protein. A shift from darkness to light conditions resulted in increased specific growth rates resulting in increased biomass formation, thus showing that light enhances growth by serving as an additional energy source. This phenomenon, however, was temporary because bacteriochlorophyll synthesis is inhibited by light. In contrast to incubation in continuous light or dark, incubation under light/dark regimen resulted in permanently enhanced biomass formation. In the dark periods, bacteriochlorophyll was synthesized at elevated rates (compared to constant darkness), thus compensating the inhibitory effect of light in the preceding period. It thus appears that the organism is well-adpated to life in environments with alternating light/dark conditions. The ecological relevance of the observations is discussed.Non-standard abbreviations BChla bacteriochlorophyll a - D dilution rate - spceific growth rate - K_s saturation constant - S_R concentration of limiting in inflowing medium of chemostat     

膝周神经射频热凝治疗顽固性膝骨关节炎疼痛的临床效果

目的:探讨膝周神经射频热凝治疗顽固性膝骨关节炎疼痛的疗效。方法:收集2013年1月至2014年1月,我院收治的顽固性膝骨关节炎疼痛患者62例,随机分为观察组与对照组,各31例。观察组予以膝周神经射频热凝联合关节腔内注射玻璃酸钠治疗,对照组单纯行关节腔内玻璃酸钠注射治疗,比较两组的临床疗效。结果:观察组治疗后VAS评分及OKS评分均显著低于对照组(P0.05);两组均未见明显并发症。结论:膝周神经射频热凝辅助治疗顽固性膝关节炎疼痛疗效显著,创伤较小,可促进关节功能的康复,值得推广应用。     

Streptomycin-resistant mutant production in a continuous-flow UV mutation device

Summary A continuous-flow UV-induced mutation device which incorporates starting strain cultivation, UV irradiation and mutant reproduction was conceptualized and tested in this study using streptomycin resistance as an indicator of mutant production. For the experimental conditions employed and populations used, the mutation frequency for streptomycin resistance ranged from 10^–4 to 10^–5 cfu/ml. These mutation frequencies are comparable with conventional batch UV mutation methods and represent a gain of 3 orders of magnitude over the spontaneous mutation frequency.