Purification and characterization of chymotrypsin-like enzyme from rat plasma

A chymotrypsin-like enzyme was purified from rat plasma, involving ammonium sulfate fractionation and chromatographgy on CM-sephadex and red sepharose. The purified enzyme effectively hydrolysed the ester substrates for chymotrypsin (N-acetyl L-tyrosine ethyl ester and N-acetyl L-tryptophan ethyl ester). The Km values for the two substrates were 2.2×10^?3M and 9.0×10^?3M respectively. The hydrolytic activity of the enzyme was inhibited by phenylmethyl sulfonyl fluoride and tosylphenylalanine chloromethylketone, suggesting the presence of serine and histidine at the active centre. The enzyme exhibited anionic nature and possessed a high molecular weight (MW 71,000) as observed by gel exclusion chromatography on Sephadex G-200. The enzyme was stable upon exposure to pH 7.0–9.0, but was inactivated upon heat treatment at 60°C for 5 min.     

Serum calcium measurement: Total versus free (ionized) calcium

Measurement of serum free (ionized) calcium (Ca⁺⁺) reflects true calcium status of the body in health and disease. Present study evaluates efficacy of Ca⁺⁺ over total calcium (CaT) in serum for calcium status. 52 subjects were enrolled for study. Anaerobic fasting blood sample for Ca⁺⁺ measurement and autoclaved plain bulb for estimation of CaT, Total protein (TP) and Albumin was used. CaT, Corrected CaT, Ca⁺⁺, Calculated Ca⁺⁺ were measured and correlated. Corrected CaT and calculated Ca⁺⁺ were derived from the measured parameters. Study group showed significant difference between CaT and corrected CaT (p<0.006), Ca⁺⁺ and calculated Ca⁺⁺ (p<0.001). Negligible correlation was observed between Ca⁺⁺ and serum protein. Positive correlation was observed between CaT and calculated Ca⁺⁺, TP and albumin. Findings indicate that Ca⁺⁺ levels are independent of serum protein status. With scrupulous sampling, Ca⁺⁺ may be a better parameter than presently used CaT for assessing calcium status in serum.     

Effect of (-)epicatechin in modulating calicum-atpase activity in normal and diabetic human erythrocytes

Aqueous extract of the wood ofPterocarpus marsupium, commonly known as ‘bijasar’, is used in Indian Ayurveda system of medicine for treatment of diabetes. The active anti-diabetic principle in its aqueous extract has been found to be (-)epicatechin, a flavonoid. The present work was undertaken to study the effect of (-)epicatechin on erythrocyte membrane Ca⁺⁺-ATPase from type 2 diabetic patients. The activity of erythrocyte Ca⁺⁺-ATPase was significantly lower in type 2 diabetics.In vitro insulin treatment of erythrocyte ghosts, resulted in the increase of Ca⁺⁺-ATPase activity in diabetic patients. Treatment with (-)epicatechin (1mM) resulted in an increase in the activity of erythrocyte Ca⁺⁺-ATPase in both normal individuals and type 2 diabetic patients. The insulin like effect of (-)epicatechin on erythrocyte membrane Ca⁺⁺-ATPase in type 2 diabetics is an interesting finding. Further work is needed to elucidate the mechanism of action of (-)epicatechin on modulation of erythrocyte membrane bound enzymes.     

An oxalate oxidase from grain sorghum leaf: Use in determination of urinary oxalate

An Oxalate oxidase (Oxalate: O₂ oxidoreductase, EC 1,2,3,4) has been purified to apparent homogeneity from leaves of 10-day old seedling plants of grain sorghum hybrid CSH-5. The enzyme exhibited maximum activity at pH 5.0 and 40°C. The rate of H₂O₂ formation was linear upto 2 min. The enzyme was strongly stimulated by Cu⁺⁺. The enzyme has greater resistance towards various cations and anions found in urine, compared to moss, barley, banana peel and bleet stem oxalate oxidases. This improved characteristic of the enzyme make it better suited for its use in the determination of urinary oxalate. A simple method of measuring oxalate in urine using this enzyme preparation is described.     

Effect of ketoacids on H<Subscript>2</Subscript>O<Subscript>2</Subscript> induced cataract

Cataract is one of the leading causes of visual disability often leading to blindness in the elderly population. One of the causes is oxidation of proteins present in lens, by hydrogen peroxide (H₂O₂). In the present study 100 goat lenses were analyzed to determine the protective efficacy of ketoacids, against the oxidative insult by H₂O₂. The ketoacids used were (pyruvate, alpha ketoglutarate and oxaloacetate), that are constantly produced endogenously. The lenses were incubated as control and experimental groups in TC-199 media for 72 hrs. H₂O₂ concentration of 10mM was used to induce cataract. The biochemical parameters measured were levels of malondialdehyde (MDA), a lipid peroxidation product and activity of glutathione peroxidase (G-Px), an enzymatic antioxidant. The results showed a significant increase in the levels of MDA and significant decrease in the activity of G-Px in the cataractous lenses as compared to control. After addition of ketoacids (pyruvate (10mM), alpha ketoglutarate (20mM) and oxaloacetate (20mM)) separately, the levels of MDA decreased significantly and the activity of G-Px increased significantly. The results suggest that the ketoacids can be very promising antioxidants for the treatment of cataract. They may also be useful in treating other disabilities related to acute and chronic oxidative stress.     

Comparison of the masses of he and h1 on a mass-spectrograph

The ratio of the masses of He : Ht was measured by comparison of He⁺⁺ with H₂¹⁺ on fourteen spectra, and the measurements give He : H¹ = 3.971283 ± 0.000042. If He = 4.00216 ± 0.00013 on the O¹⁶ scale as given by Aston, then H¹ = 1.007775 ± 0.000035 in excellent agreement with the value 1.00778 reported by Aston.A method is suggested for the determination of the mass of H² in terms of He and C.     

Enhanced production of glutaminase-free l-asparaginase by marine Bacillus velezensis and cytotoxic activity against breast cancer cell lines

BackgroundThe increasing rate of breast cancer globally requires extraordinary efforts to discover new effective sources of chemotherapy with fewer side effects. Glutaminase-free l-asparaginase is a vital chemotherapeutic agent for various tumor malignancies. Microorganisms from extreme sources, such as marine bacteria, might have high l-asparaginase productivity and efficiency with exceptional antitumor action toward breast cancer cell lines.Resultsl-Asparaginase-producing bacteria, Bacillus velezensis isolated from marine sediments, were identified by 16S rRNA sequencing. l-Asparaginase production by immobilized cells was 61.04% higher than that by free cells fermentation. The significant productivity of enzyme occurred at 72 h, pH 6.5, 37°C, 100 rpm. Optimum carbon and nitrogen sources for enzyme production were glucose and NH₄Cl, respectively. l-Asparaginase was free from glutaminase activity, which was crucial medically in terms of their severe side effects. The molecular weight of the purified enzyme is 39.7 KDa by SDS-PAGE analysis and was ideally active at pH 7.5 and 37°C. Notwithstanding, the highest stability of the enzyme was found at pH 8.5 and 70°C for 1 h. The enzyme kinetic parameters displayed V_max at 41.49 μmol/mL/min and a K_m of 3.6 × 10⁻⁵ M, which serve as a proof of the affinity to its substrate. The anticancer activity of the enzyme against breast adenocarcinoma cell lines demonstrated significant activity toward MDA-MB-231 cells when compared with MCF-7 cells with IC₅₀ values of 12.6 ± 1.2 μg/mL and 17.3 ± 2.8 μg/mL, respectively.ConclusionThis study provides the first potential of glutaminase-free l-asparaginase production from the marine bacterium Bacillus velezensis as a prospect anticancer pharmaceutical agent for two different breast cancer cell lines.How to cite: Mostafa Y, Alrumman S, Alamri S, et al. Enhanced production of glutaminase-free L-asparaginase by marine Bacillus velezensis and cytotoxic activity against breast cancer cell lines. Electron J Biotechnol 2019;42. https://doi.org/10.1016/j.ejbt.2019.10.001.     

明代以前黑河流域耕地面积重建

受人类活动变迁影响,黑河流域作为我国西北地区重要产粮基地以及大规模绿洲农业开发最早地区之一,其境内的耕地规模自古至今变化十分频繁.由于文献记载的有限性和疏漏性,目前关于区域内明代以前的耕地面积历史变化情况的分析十分欠缺.本文选择文献较丰富的汉、唐和元代,依据历史文献资料和前人研究成果,以人口数据为基础,运用基于人均耕地面积和粮食产量两种途径重建了黑河流域明代以前耕地面积.前者按各时期屯田制度,结合人均垦地面积分别重建民户耕地和军屯占地情况,汇总两类耕地面积进行重建,后者利用人均粮食消耗、耕地单产情况估算人均耕地需求,再结合人口数据重建耕地总量.重建结果表明黑河流域明代以前耕地面积以西汉时期为最大,达(16.30～19.49)万hm2,其后总体呈下降趋势,东汉、唐代与元代的面积分别为(9.57～11.80)万hm2,(3.59 ～3.93)万hm2和3.19万hm2.对比表明两种重建结果基本一致,证实了重建结果具有可靠性并在一定程度上可以反映研究时期内耕地规模的变化趋势.     

The blackening of photographic plates by positive ions of the alkali metals

A short review is included of previous work on the blackening of photographic plates by positive rays and rays of an analogous nature.The blackening of Eastman x-ray plates, by positive ions, has been measured as a function of the energy of the ions of Li, Na, K, Rb, and Cs. The energy of the ions required to produce a photographic density of D = 0.3 with a one minute exposure at a current density of 1.32 × 10^?8 amperes per cm.² ranged from 1420 electron-volts in the case of cæsium to 860 electron-volts in the case of Li⁷. Approximately 10⁵ ions are required at these energies to render developable one silver-halide grain. For a threshold density, D = 0.04, under the same conditions the energy ranged from approximately 920 to 460 electron-volts for Cs and Li⁷ respectively.Sensitivity comparisons were made between x-ray plates and process and schumannized process plates. Potassium ions with an energy as low as 137 electron-volts were recorded on Schumann plates, and it is possible that positive ions of one-third this energy can be recorded.     

天津北三河水系雨洪水资源潜力的估算及其应用

基于资源水利的理念,以雨洪水资源为研究对象,针对其动态性分别引入理论潜力、可实现潜力、现实潜力及待开发潜力的概念及算法。以天津北三河水系为典型区域,分别计算了各流域和整个水系的各个频率年的自产水量、理论潜力、可实现潜力,给出了各频率来水情况下雨洪水资源潜力的年内分配过程,并以待开发潜力为主要关注对象,对其进行频率分析,计算得到50%、20%、10%、5%各频率年下的待开发潜力值依次为4.42×10⁸m³、12.96×10⁸m³、20.02×10⁸m³、27.35×10⁸m³,为以后的雨洪水资源利用模式的制定提供了依据。     

庐山自然保护区森林生态系统服务价值评估

森林生态系统具有多种重要的生态功能,分析与评价森林生态系统服务功能的价值已成为当前生态学与生态经济学研究的前沿课题。根据森林生态系统服务价值的计算方法,估算了庐山自然保护区森林生态系统7项服务价值总量为26.1086×108元/年。庐山森林生态系统服务功能的直接经济价值和间接经济价值分别为16.1605×108元/年和9.9481×108元/年,直接经济价值是间接经济价值的1.62倍。在森林生态系统各项服务功能价值的贡献之中,其大小顺序依次为:森林游憩>固CO2释O2>土壤保持>净化空气>涵养水源>林果产品>保护生物多样性。森林游憩价值以16.0838×108元/年稳居第1位,占总价值的61.60%;其次为固CO2释O2的价值,占总价值的32.91%,两项合计占到95.51%。庐山森林生态系统服务在价值构成上异于全国一般规律的原因,主要在于庐山自然保护区高度发达的旅游产业和小规模的林业生产活动等。森林生态系统价值评估有助于人们对于森林生态系统价值的认识,有利于区域可持续发展战略的实施和推进。     

Plasma Neutrophil Elastase, α<Subscript>1</Subscript>-Antitrypsin, α<Subscript>2</Subscript>-Macroglobulin and Neutrophil Elastase–α<Subscript>1</Subscript>-Antitrypsin Complex Levels in patients with Dengue Fever

Dengue fever (DF) is characterized by systemic inflammatory response including neutrophil activation leading to uncontrolled elastase activity. This study was aimed to measure the activity of plasma neutrophil elastase (NE), its endogenous inhibitors α₁-antitrypsin (α₁-AT) and α₂-macroglobulin (α₂-MG) and elastase in complex with α₁-AT (NE–α₁-AT complex) in DF. 50 dengue patients [39 DF and 11 dengue hemorrhagic fever (DHF)] and 52 healthy subjects were included in the study. NE was measured using N-succinyl-tri-alanine-p-nitroanilide as substrate. α₁-AT, α₂-MG and NE–α₁-AT complex were estimated by ELISA. The result analysis indicated that the dengue patients had significantly higher elastase activity with significantly reduced inhibitor levels compared to controls. Between DF and DHF patients, DHF group had significantly higher elastase activity. In conclusion, significantly elevated NE and reduced inhibitors level in dengue fever indicate these parameters could be of significance in DF particularly for the assessment of progression of inflammatory processes.     

基于GIS技术的中国农田磷素养分收支平衡研究

基于农田养分收支平衡模型、农业经济统计数据,结合GIS技术,从国家、省域、县域3个层面研究了我国农田磷素的平衡特征,并利用GIS技术对研究结果进行了空间表达与分析。主要结论：①我国农田磷素(P)投入总量为610×10⁴t,支出总量为328×10⁴t,农田磷素(P)盈余282×10⁴t,平均单位耕地盈余0.029t/hm²。从大区域来看,我国农田磷素盈余趋势为从我国东部地区农田向西部地区农田逐渐减少;②农田磷素亏缺的县域单元数占全部县域单元数的12.81%,其耕地面积占全国耕地总面积的16.11%。也就是说,虽然在全国层面上磷素赢余量很大,但是并不代表每个县域单元农田磷素都是盈余的,在进行肥料资源宏观配置时必须考虑这些问题;③在全国层面上,磷肥、有机磷肥、其它来源的磷肥占农田磷养分总投入的比例分别为77.11%、22.23%、0.66%,农田磷素养分的投入以磷肥为主,在全国层面上,由人畜禽粪尿提供的磷素占全部有机磷肥投入的比重为85.25%;④全国农田磷素生物产出为294×10⁴t,占农田磷素总支出的比重为89.90%,农田磷素生物产出是农田磷素支出的主要部分。     

白洋淀流域湿地生态水权的实证研究

湿地生态水权是分配给湿地生态系统使用水资源的权利。明确湿地生态水权对于建立湿地补水机制具有重要意义。进行湿地生态水权分析时,应遵循以下原则：①基本生活用水保障原则;②生产与生态、上游与下游统筹协调原则;③尊重现状用水原则;④合理用水原则。以此为基础,提出了湿地生态水权的计算方法,并选取白洋淀湿地进行了实例分析。结果显示,白洋淀湿地50%保证率的年生态水权量为13130×104m3,大于湿地适宜生态需水量;75%保证率的年生态水权量为8585×104m3,大于湿地最小生态需水量;而95%保证率的年生态水权量只有3891×104m3,远小于其最小生态需水量。在50%和75%保证率下,用白洋淀湿地自身的水权量为白洋淀补水,可分别满足其适宜和最小生态需水量要求;而95%保证率下,按照最小生态需水量为白洋淀补水,也需占用其他地区（白洋淀上游或外流域）的水权,需要对此进行补偿     

近20年来伊犁新垦区土地利用/覆被变化分析

本文基于1985年、2000年和2008年3期土地利用数据,对新疆伊犁新垦区土地利用格局时空变化进行了定量研究。结果显示：1985年～2008年间,耕地净增加4.99×10⁴hm²,面积比由38%上升至57%;未利用地增长仅次于耕地,增长面积为1.07×10⁴hm²,水域,林地,建设用地都呈增长趋势;草地为唯一减少的土地利用类型,缩减7.02×10⁴hm²,面积比由49%缩减为36%。通过对土地利用变化格局的分析可以得出,农业开垦是新垦区土地利用方式变化最主要的驱动力因素,草地面积减少是其他土地类型面积增加的主要来源,盐碱地增多和沼泽减少反映了该地区存在因农业开垦而导致的自然环境恶化现象。     

基于森林资源清查的迪庆州森林生物量及生产力研究

利用森林蓄积量推算森林生物量和生产力的方法和GIS技术,系统研究了迪庆州森林类型的植被生产力。结果表明,虽迪庆州主要森林类型的植被生产力与中国主要森林植被生产力一致,但其平均生物量及平均生产力高于中国平均水平,这一结果符合迪庆林情,说明材积推算生物量法（材积源生物量法）适合用于该区域森林植被生产力研究;迪庆州森林总生物量为2．22亿t,其中乔木林2．15亿t,灌木林（含疏林和竹林）0．07亿t;乔木林和灌木林的总生产力分别为1723．77万t/a和386．25万t／a;各乡镇乔木林／森林的总生物量呈现随与澜沧江和金沙江距离的增加而增大;澜沧江和金沙江干流流经乡镇的森林具有较低的生物量和较高的生产力。因此,迪庆州林分改造与生态建设的毒点将是澜涂江和金沙江两岸的河谷地带。     

The magnetic deflection experiments of Curtiss and of Mott-Smith

We have carried out a geometrical analysis which applies to that type of cosmic ray deflection experiment in which an extended region of magnetic field lies between the lower two of three or more Geiger-Mueller counters arranged in line for counting coincident discharges. It is apparent that charged particles of sufficiently low energy will be deviated away from the last counter and that the counting rate will therefore be reduced by application of the field. This paper presents a method for computing what proportion of electrons of a given energy will be eliminated by application of the field. The method is extended to include a constant loss of energy per unit path length as the particle traverses an iron core. The results of the experiments of Curtiss and of Mott-Smith are interpreted in the light of these calculations. Curtiss' result could be explained if all rays were electrons of 4 × 10⁸ volts energy. One may conclude from his observation that if all the radiation consists of positive or negative electrons, the fraction between 2 × 10⁷ volts and 1.5 × 10⁸ volts is less than 30 per cent. of the total above 2 × 10⁷, and that the fraction between 2 × 10⁷ and 10⁹ is greater than 30 per cent. A comparison of Curtiss' and Mott-Smith's experiments yields no reason for doubting the correctness of using the magnetic induction B when computing the deflection within iron. Nor does it necessarily sustain this procedure. An experiment by W. F. G. Swann and the writer is at present under way for the purpose of securing, if possible, more conclusive evidence on this point.     

Role of prostaglandin in the regulation of gastric H+—Transporting system

Prostaglandins and (PG) have been reported to be an important gastric acid suppressive factor. However, the mechanism underlying is yet to be clearly established. In vitro study with gastric microsomes in presence of both PGE₂ and PGI₂ shows a stimulation of gastric H⁺ K⁺-ATPase activity below 1X10⁻⁶M and 2.5X10⁻⁷M concentrations respectively. However, with further increase in concentrations of both PGE₂ and PGI₂, H⁺, K⁺-ATPase activity shows an inhibition but PGI₂ completely obliterates the K⁺ stimulated part of H⁺, K⁺-ATPase activity at higher concentration. The H⁺-ion transport study using chambered frog gastric mucosa shows that both PGE₂ and PGI₂ inhibit H⁺-ion transport at 5X10⁻⁶ M and 10X10⁻⁶M concentrations respectively but the effect of PGI₂ is reversible. These differential effects of PGE₂ and PGI₂ on microsomal H⁺, K⁺-ATPase and on H⁺ transport my be caused by the differential effects of these phospholipid mediators with the gastric mucosal cell membrane. This in vitro investigation shows the role of prostaglandin (s) as a physiological switch/regulator of gastric H⁺ ion transport leading to the cessation of gastric acid secretion.     

桂林市水资源可持续利用定量测度与动态分析

为了定量评价水资源可持续利用的状态和程度,在阐述水资源足迹内涵的基础上,通过构建实体水消费、产品水消耗和生态水需求等账户对2000年-2009年桂林市的水资源利用进行定量测度,并根据水资源匮乏度和万元GDP水资源足迹等评价指标对其进行动态分析.结果表明:10年来,桂林市的水资源足迹总体呈上升趋势,水资源的利用越来越接近不可持续的临界状态;实体水消费在水资源足迹中占的比重最大,而农业灌溉用水又占据了实体水消费的80％以上,今后应进一步调整产业结构,减少传统农业尤其是猪肉、牛肉等水资源密集型产品的生产,大力发展电子信息产业和旅游业;尽管万元GDP水资源足迹逐步下降,但与国内发达地区相比还存在很大差距,水资源的利用效率和效益还应进一步提高.