人类活动影响下新疆生态环境的一些变化

人类活动引起的新疆生态环境变化主要有以下几方面:1.河流流程缩短,河水矿化度和泥沙含量增加;2.湖泊水位下降,湖面缩小或变干,湖水矿化度升高;3.森林破坏,面积缩小;4.草场的产草量降低,牧草质量下降; 5.土壤次生盐渍化、沼泽化和肥力下降;6.土地沙漠化不断扩大。     

Imaging erythrocytes under physiological conditions by atomic force microscopy

Since its invention in the mid 1980s atomic force microscopy has revolutionised the way in which surfaces can be imaged. Close to atomic resolution has been achieved for some materials and numerous images of molecules on surfaces have been recorded. Atomic force microscopy has also been of benefit to biology where protein molecules on surfaces have been studied and even whole cells have been investigated. Here we report a study of red blood cells which have been imaged in a physiological medium. At high resolution, the underlying cytoskeleton of the blood cell has been resolved and flaws in the cytoskeleton structure may be observed. Comparison of the normal 'doughnut' shaped cells with swollen cells has been undertaken. Differences in both the global properties of the cells and in the local features in cytoskeleton structure have been observed.     

Photomyoclonic seizures in the baboon, Papio papio.

The inborn seizure response of Papio papio to intermittent light stimulation has been reviewed as a model of human epilepsy. The electrographic and clinical features have been described and useful methodology has been outlined. A diurnal cyclicity in seizure responsiveness has been described with greatest seizure severity at 8 AM in parallel with a rise in urinary output of cortisol. Hormonal influences on the seizure response have been described for ethinyl estradiol, thyroxin, and triiodothyronine. Evidence regarding neurotransmitter involvement has been reviewed. Data regarding use of the animal for anticonvulsant testing in single and chronic doses has been discussed. Particular advantages of the model for study of age-related drug effects and the assessment of the effects of chronically administered anticonvulsant agents on learning and memory have been described.     

Melanocyte-directed enzyme prodrug therapy (MDEPT): development of a targeted treatment for malignant melanoma.

A novel prodrug rationally designed to function as a tyrosinase substrate has been synthesised to allow targeted treatment of malignant melanoma. This agent has been evaluated for tyrosinase-mediated drug release, and has been shown to act in the desired manner. Furthermore, differential cytotoxicity has been demonstrated in cell lines which express tyrosinase and those which do not.     

Cloning, mapping and gene product identification of rhaT from Escherichia coli K12

Rhamnose utilization requires the function of a specific rhamnose transport system. Rhamnose transport mutants have been isolated and characterized. The structural gene, rhaT, encoding the rhamnose permease has been cloned from Escherichia coli. rhaT has been mapped in the rha locus (87.7 min) by analysis of cotransduction with glpK and other rha markers. The precise location of the gene has been determined by complementation analysis of rhamnose transport mutants transformed with recombinant plasmids containing different fragments of the cloned region. Gene order (counterclockwise) is established as glpK . . . rhaT-rhaR-rhaS-rhaB-rhaA-rhaD. The gene product has been identified by expression of rhaT in a T7 RNA polymerase/promoter system. This 23 kDa protein has been assigned to the rhaT product and has been shown to be located in the cell membrane.     

Characteristics of Symmetric Surface Plasmon Polariton Mode in Glass–Metal–Glass Waveguide

The propagation characteristics of symmetric surface plasmon polariton mode in a glass–metal–glass waveguide are presented. Gallium lanthanum sulfide has been taken as the glass and silver (Ag) has been used as the metal. The analysis has been done both numerically and analytically. A two-dimensional finite-difference time-domain-based simulation model has been developed in order to analyze the propagation characteristics numerically. The obtained results using numerical and analytical methods have been compared and a very good agreement has been found.     

The effect of oligomycin on rat liver mitochondria respiring in state 4

It has been found that oligomycin inhibits up to at least 50% state-4 mitochondrial respiration. A time dependence of oligomycin inhibition has been shown. A titration curve for state-4 respiration of sigmoidal profile has been presented. The possibility of misreading this oligomycin effect, so far never reported, has been excluded by evaluating the quality of mitochondrial preparations used in respect to their morphological, functional and electrochemical properties. The conclusion has therefore been put forward that the most part of respiration in steady-state-4 is driven by ATP synthesis.     

Comparison of lipase-catalysed esterification in supercritical carbon dioxide and in n-hexane

Summary Oleic acid esterification by ethanol has been performed by an immobilized lipase fromMucor miehei in supercritical carbon dioxide and in n-hexane as solvents. In both media, determination of apparent kinetic constants has been achieved and influence of water content has been shown to be different due to various rates of water solubilities. Stability of the lipase has been proved to be correct and similar in both solvents. Inhibition by ethanol excess has been found but is greater in n-hexane. That can explain the higher initial velocities obtained in supercritical carbon dioxide for the highest ethanol concentrations.     

Productivity improvement in xanthan gum fermentation using multiple substrate optimization

A novel and more comprehensive formulation of the optimal control problem that reflects the operational requirements of a typical industrial fermentation has been proposed in this work. This formulation has been applied to a fed-batch bioreactor with three control variables, i.e., feed rates of carbon source, nitrogen source, and an oxygen source, to result in a 148.7% increase in product formation. Xanthan gum production using Xanthomonas campestris has been used as the model system for this optimization study, and the liquid-phase oxygen supply strategy has been used to supply oxygen to the fermentation. The formulated optimization problem has several constraints associated with it due to the nature of the system. A robust stochastic technique, differential evolution, has been used to solve this challenging optimization problem. The infinite dimensional optimization problem has been approximated to a finite dimensional one by control vector parametrization. The state constraints that are path constraints have been addressed by using penalty functions and by integrating them over the total duration to ensure a feasible solution. End point constraints on final working volume of the reactor and on the final residual concentrations of carbon and nitrogen sources have been included in the problem formulation. Further, the toxicity of the oxygen source, H(2)O(2), has been addressed by imposing a constraint on its maximum usable concentration. In addition, the initial volume of the bioreactor contents and feed concentrations have been handled as decision variables, which has enabled a well-grounded choice for their values from the optimization procedure; adhoc values are normally used in the industry. All results obtained by simulation have been validated experimentally with good agreements between experimental and simulated values.     

Persistence of bacterial pathogens as a physiological phenomenon

The complex ecosystem of humans and microbes has been presented as an associative symbiosis based on a mutual support of symbionts with different consequences for them. Conditions for the persistence of bacteria have been defined: their resistance to environmental factors, antagonism in biocenosis, and stability to withstand host defense mechanisms. The key role of bacterial peptidoglycan has been defined for their survival in an infected organism, and the classification for persistent mechanisms of pathogens has been given. The group of bacterial secreted protease providing microbial resistance to defense factors of the organism has been described. Host colonizing resistance has been presented as a physiological regulatory system controlling bacterial penetration into an organism. Regulatory mechanisms for bacterial persistence have been discussed.     

Sampling Schemes for Studying Growth of Children

Efficiency of linked cross-sectional scheme has been compared with pure longitudinal schemes for generalised estimation of norm relaxing the condition of constancy of variances. The relevant theory of estimation has been developed and the expression for the optimum estimators alongwith their variances have been derived. The percentage gain in efficiency has been calculated. It has been observed that for higher values of Q, percentage gain in efficiency of proposed scheme over cross-sectional is very high.     

Molecular mapping and tagging of genes in crop plants

In India, molecular mapping and tagging of agronomically important genes using RFLP and RAPD markers have been carried out in three different crops: rice, mustard and chickpea. In rice, tagging of genes for resistance to gall midge and blast has been accomplished. Molecular mapping of cooking quality traits in rice is in progress. For fingerpringting rice cultivars, suitable probe enzyme combinations have been identified. In mustard, a partial RFLP linkage map has been constructed and one of the yellow seed-coat colour loci has been mapped. Significant associations of RFLP markers with quantitative traits have also been established. Potential use of RAPD markers to identify heterotic groups among mustard accessions has been demonstrated. In chickpea, the occurrence of considerable interspecific DNA polymorphism as revealed by RAPD analysis has facilitated construction of a partial linkage map.     

Outline of a novel architecture for cortical computation

In this paper a novel architecture for cortical computation has been proposed. This architecture is composed of computing paths consisting of neurons and synapses. These paths have been decomposed into lateral, longitudinal and vertical components. Cortical computation has then been decomposed into lateral computation (LaC), longitudinal computation (LoC) and vertical computation (VeC). It has been shown that various loop structures in the cortical circuit play important roles in cortical computation as well as in memory storage and retrieval, keeping in conformity with the molecular basis of short and long term memory. A new learning scheme for the brain has also been proposed and how it is implemented within the proposed architecture has been explained. A few mathematical results about the architecture have been proposed, some of which are without proof.     

Acute oxygen supply by infusion of hemoglobin solutions.

Preparations of 6% human hemoglobin have been investigated for 4 years. While the oxygen dissociation curve is shifted to the left, the hemoglobin solution has been shown to deliver oxygen adequately to the tissues in animal studies. Intracorporeal fate has been investigated by 131-I tagging, and the hemoglobin has not been found to accumulate in the tissues. Intravascular half-life has varied between 1.5 and 3.5 hours.     

A quantitative assay for total fructans in burdock (Arctium spp.) roots

A quantitative assay of the total content of polysaccharides (fructans) in burdock roots in fructose equivalent has been elaborated. Extraction of free carbohydrates and polysaccharides has been studied using spectrophotometry and quantitative HPTLC. The optimal parameters for extracting the target group of compounds have been determined. Metrological analysis of the elaborated assay has been performed. It has been shown that the detection error does not exceed 3%.     

Postoperative hypoparathyroidism: risk of complications]

For assessing the risk of adverse complications of surgery the group of 130 patients with post-operational hypoparathyroidism was analysed. Surgical hypoparathyroidism has been diagnosed in 51% of operated on thyroid gland patients. Laryngeal nerves have been damaged in 46.6% of patients. The injury to laryngeal nerves has been irreversible in 2/3 of patients, and reversible in the remaining 1/3. Cataract, nephrolithiasis and vitamin D3 intoxication have been observed in some cases before surgery. Their incidence increased in severe surgical hypoparathyroidism. Osteoporosis of the spine has been diagnosed in 49% of patients including some with vertebral fractures. No correlation between the degree of spine osteoporosis and diagnosis before surgery, number of operations on thyroid gland, and type of therapy has been noted. The symptoms of hypercalcemia have been diagnosed in 5 patients out of which hypercalcemia has been transient in 2 patients, and lasted for 1-5 months in the remaining 3 patients. The results of 7,873 analyses of mineral metabolism have been assessed. Hypocalcemia has been found in 38.4%, hypercalcemia in 1.6%, hypomagnesemia in 25.7%, hyperphosphatemia in 41.5%, decreased alkaline phosphatase serum activity in 28.7%, and hypercalciuria in 22.4% of cases. Surgical hypoparathyroidism is frequently accompanied by surgical hypothyroidism and injury to the recurrent laryngeal nerves.     

一种植物生长激素-N'-(5-硝基-2-羟基苯亚甲基)-3,5-二羟基苯甲酰肼的合成、晶体结构和抗菌活性

目的:合成并表征一种属于植物生长激素的席夫碱类化合物.方法:由5-硝基水杨醛和3,5-二羟基苯甲酰肼在甲醇溶液中反应得到N′-(5-硝基-2-羟基苯亚甲基)-3,5-二羟基苯甲酰肼.结果:用单晶X-射线衍射法测得其结构并表征,同时通过抗菌实验证明其在一定浓度下具有明显的抗菌活性.结论:这种席夫碱类化合物在某种程度上具有明显的抗菌活性.     

Morphological measurements on filamentous microorganisms by fully automatic image analysis

Characterization of mycelial morphology is important for physiological and engineering studies of filamentous fermentations, and in the design and operation of such fermentations. Image analysis has been developed as a method for this characterization, and has been shown to be faster and generally more accurate than previous methods. A fully automatic system has been developed, in which speed is gained, but with loss of accuracy in some cases. The method has been tested on Streptomyces clavuligerus and Penicillium chrysogenum P1 batch fermentations. It has also been tested on a fed-batch Penicillium chrysogenum P2 fermentation, in which the medium contained solid ingredients. Fully automatic image analysis for morphological characterization of filamentous microorganisms is an important development which will make practical many engineering and physiological studies of such fermentations that have so far not been completely satisfactory.     

Tau Mediated Neurodegeneration: An Insight into Alzheimer’s Disease Pathology

Extracellular accumulations of Aβ, hyperphosphorylation of tau and intracellular neurofibrillary tangle formation have been the hallmarks of Alzheimer’s Disease (AD). Although tau and its phosphorylation play a pivotal role in the normal physiology yet its hyperphosphorylation has been a pathological manifestation in neurodegenerative disorders like AD. In this review physiology of tau, its phosphorylation, hyperphosphorylation with the intervention of various kinases, aggregation and formation of paired helical filaments has been discussed. A brief account of various animal models employed to study the pathological manifestation of tau in AD and therapeutic strategies streamlined to counter the tau induced pathology has been given. The reasons for the failure to have suitable animal model to study AD pathology and recent success in achieving this has been included. The role of caspase cascade in tau cleavage has been emphasized. The summary of current studies on tau and the need for future studies has been accentuated.     

Purification and substrate specificity of BcmI restriction endonuclease

A strain producing the new specific restriction endonuclease BcmI has been found in the Bacillus generum. The enzyme has been purified by chromatography on the blue sepharose, phosphocellulose PII, heparin sepharose. The analogous purification has been obtained when the blue sepharose has been substituted for the orange sepharose, the home produced sorbent. The BcmI enzyme has been shown by the substrate specificity definition to be an isoschizomer of the restriction endonuclease ClaI.