THE ACCUMULATION OF ELECTROLYTES : VII. ORGANIC ELECTROLYTES PART 2

Analyses have been made of the inorganic constituents of the juices expressed from the leaves of Rheum, Rumex, and Oxalis. It has been shown that in all cases there is a large excess of inorganic cations over anions in the sap, the average ratio of cations to anions being 3.8 (Part 1, p. 239). The ash analyses of plant tissues (chiefly leaves) reported in the literature have been examined critically, and it has been shown that the preponderance of inorganic cations over inorganic anions in the ash and in the sap is general. It has been concluded that the excess of inorganic cations is consistent with the view that cations pass into the protoplasm chiefly in the form of hydroxides, and are accumulated either in the form of organic salts (such as the oxalates) or in non-polar linkage. It has been concluded that practically all the potassium and sodium found in plant ash must have been present originally in the form of soluble ionogenic compounds, but that a considerable part of the calcium and magnesium may have been present originally in the form of insoluble salts or as components of non-polar compounds. The methods whereby the cations, particularly potassium, may have been accumulated have been discussed, and it has been concluded that as it does not seem very probable that they enter chiefly as nitrates or bicarbonates we may suppose that they go in to a large extent as hydrates: this is highly probable in the case which has been most carefully investigated (Valonia).     

The organization of capsaicin-sensitive visceral afferent systems

It has become clear that a number of neuropeptides are found in sensory nerves, some of which have been identified in visceral afferents. The best studied peptide is substance P, which has been localized in a population of capsaicin-sensitive visceral afferents. It has been established that there are a varied proportion of substance P-containing afferents in different visceral structures. In general, the peripheral termination of these nerves is around blood vessels. The central terminations of visceral afferents are in laminae I and V in the dorsal horn of the spinal cord. Substance P has been localized in these laminae and appears to be capsaicin-sensitive and therefore of sensory origin. Recently, substance K, which is derived from the same gene as substance P, has been found in visceral structures. Calcitonin gene-related peptide has been found in certain viscera to be contained in capsaicin-sensitive nerves. The contribution that other peptides make to visceral afferent innervation is not known.     

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.     

医院整体医疗管理模式探索历程与实施成效

医院整体医疗管理模式是以医学整体论、生物—心理—社会医学模式为指导,为满足社会民众的健康需求而创新的医院医疗管理新模式。经过10多年的实践与探索,拓宽了院前院后医疗保健功能,提升了医疗质量与医疗服务效能,融洽了医患关系,为医院赢得了良好的声誉,成效显著。     

Sensitivity of parasites to free radical damage by antiparasitic drugs

Over the last few years a remarkable progress has been made in the understanding of parasites biochemistry, molecular biology, and immunology. This progress is especially encouraging in that emphasis on drug development is shifting from random screening towards a more rational approach. A number of peculiar aspects characteristic of parasites which are not present in other organisms and that might be exploitable for the design of specific agents have been described recently. One of these aspects is their deficiency in defense mechanisms against oxygen toxicity. Catalase is absent in many parasites. Distinct superoxide dismutases have been detected and specific inhibitors of these enzymes have been investigated. Glutathione is absent in some anaerobic protozoa. Peroxidase and reductase activities dependent on a glutathione-spermidine cofactor termed trypanothione have been detected in several trypanosomatids and apparently replace the glutathione peroxidase-glutathione reductase system of other eukaryotic cells. Free radical intermediates have been shown to be involved in the reaction of enzymes present in anaerobic protozoa. In addition, a number of antiparasitic agents have been shown to exert their actions through a free radical metabolism: nitro compounds used against trypanosomatids, anaerobic protozoa and helminths; crystal violet used in blood banks to prevent blood transmission of Chagas' disease; the antimalarial primaquine, chloroquinine, and quinhasou; and quinones active in vitro and in vivo against different parasites.     

Koi herpesvirus (KHV) and KHV disease (KHVD) – a recently updated overview

Over the last years, there has been an enormous increase in the knowledge on koi herpesvirus (KHV), koi herpesvirus disease (KHVD), pathogenesis and virus variants. Different KHV lineages have clearly been identified, possible genomic changes during replication in different cell cultures at different temperatures but also in several hosts have been identified, a persistent stage of infection has been specified and it has been shown that infection with KHV is not host specific at all, but KHVD is. Additionally, it has been shown that it is possible to combat KHVD by immunization with inactivated and attenuated live vaccines using different delivery systems but also to benefit from alternative treatments with e.g. exopolysaccharids obtained from Arthrospira platensis.     

Advances and prospects: biotechnologically improving crop water use efficiency

Bio-water saving can be defined as the reduction of crop water consumption employing biological measures. This is the focus of efforts to save water in agriculture. Different levels of water-use efficiency (WUE) have been developed. The genetic diversity of WUE has been confirmed in several crops. WUE is the basis of bio-watering and physiological WUE is the key. The degree to develop physiological WUE potential decides the performance of bio-watering in the field. During this process, fine management is important. Thus bio-watering is closely related to WUE. Crop WUE has improved and evolved as a result of breeding programs. Many WUE genes have been located in different genomic and aneuploid materials and have been mapped by various molecular markers in a number of crops. Two genes, (Erecta and alx8), which control water use efficiency; have been cloned in Arabidopsis thaliana. Eleven WUE genes have been identified by microarray analysis. Six genes associated with drought resistance and photosynthesis have been transfered into crops which have resulted in improving WUE and drought resistance. WUE is important on the basis of functional identification of more drought resistant gene resources. The popularity on the industrial-scale of transgenic plants is still in its infancy and one of the reasons for this is the lack of knowledge regarding molecular mechanisms and it is a very immature technology. Enhanced agricultural practices and the theoretical aspects of improving crop WUE have been developed and are discussed in this review paper. Rapid progress will be made in bio-water savings and that crop WUE can be substantially improved under both favorable and unfavorable water-limited environments. This will be achieved by a combination of traditional breeding techniques and the introduction of modern biotechnology.     

Thrombophilia and pregnancy

Pregnancy is hypercoagulable state. The field of thrombophilia; the tendency to thrombosis, has been developed rapidly and has been linked to many aspects of pregnancy. It is recently that severe pregnancy complications such as severe preeclampsia intrauterine growth retardation abruptio placentae and stillbirth has been shown to be associated with thrombophilia. Recurrent miscarriage and has also been associated with thrombophilia. Finally, thromboembolism in pregnancy as in the non-pregnant state is linked to thrombophilia. In this review all aspects of thrombophilia in pregnancy are discussed, and also all prophylactic and therapeutic implications.     

Boron,Chromium, Manganese,and Nickel in Agricultural Animal Production

This paper provides an overview of research that has been conducted with manganese (Mn), chromium (Cr), nickel (Ni), and boron (B) in poultry, swine, and ruminants. Manganese is an essential trace mineral that functions as an enzyme component and enzyme activator. A deficiency of Mn results in a variety of bone abnormalities, and Mn deficiency signs have been observed under practical conditions in poultry and cattle. Chromium can potentiate the action of insulin, but whether Cr is an essential trace mineral is controversial. Insulin sensitivity has been enhanced by Cr in cattle, swine, and broilers. Responses to Cr supplementation have been variable. Production responses to Cr supplementation have been most consistent in animals exposed to various stressors (heat, cold, weaning, etc). The legality of supplementing Cr to animal diets varies among countries, Cr sources, and animal species. A specific biochemical function for Ni and B has not been identified in mammals. Signs of Ni deficiency have been produced experimentally in a number of animal species. Nickel may affect rumen microbial fermentation in ruminants, as Ni is a component of bacterial urease and cofactor F₄₃₀ in methanogenic bacteria. There is little evidence that dietary Ni limits animal production under practical conditions. Beneficial effects of B supplementation on growth and bone strength have been seen in poultry and swine, but results have been variable.

     

Physiological effects of dominance hierarchies: laboratory artefacts or natural phenomena?

Studies of fish behaviour have demonstrated the existence of social interactions that result in dominance hierarchies. In environments in which resources, such as food, shelter and mates, are limited, social competition results in some fish becoming dominant and occupying the most profitable positions. This behaviour has been observed in natural environments and also in many laboratory‐based experiments. When two fish have been confined in a small tank, one of them usually has exhibited behaviour that suggests it is dominant over the other submissive animal. Physiological consequences of social interaction can be seen in both dominants and subordinates but are more extreme in the subordinate. However, this scenario is without doubt an artificial situation. Fewer experiments have been conducted using laboratory experiments that are more socially and physically complex than those experienced by dyads in tanks. In simple fluvial tanks, through which water is recirculated, the physiological responses of fish to social competition have generally been qualitatively similar to those recorded among dyads. However, when environmental disturbances, complex resource distributions, increase in water flushing, presence of predators and competing species of fish have been included in experimen‐tal designs, there have been fewer, diminished or no physiological dierences between dominant and subordinate fish. There have been very few studies of physiology in relation to dominance in natural habitats, and those that have been conducted suggest that under some circumstances hierarchies may cause less intense physiological responses than have been suggested based on results of laboratory studies in simple environments. Possible reasons for these variations are discussed. The need is identified for a well structured experimental approach to the investi‐gation of the causes and consequences of hierarchies if the ecology of wild fish is to be modelled eectively based on physiological processes. It is also suggested that the further development and application of techniques for monitoring physiologies of fish in the wild is important.     

The Widespread Occurrence of Polyphosphate in Lower Plants

The widespread occurrence of polyphosphate (PoP) in lower plantsis described. PoP granules have been cytochemically detectedin algae, slime moulds, and mosses. A systematic survey is givenof lower plants in which the occurrence of PoP has been demonstratedwith both the present studies and previous investigations. The localization of PoP in cells has been studied. PoP granuleshave been observed to be present in the cytoplasm, the cytoplasmicvacuole, and in chloro-plasts of different algae. In Zygnemataceaeand in mosses PoP granules are localized in the chloroplastswhich also contain pentose nucleic acid. A relationship between PoP, pentose nucleic acid (PNA), andgrowth has been found and is discussed. A possible in situ synthesisof PoP in chloroplasts from phosphorylated intermediates ofthe photosynthetic process is suggested.     

Characterization of cytosine permeation in Saccharomyces cerevisiae.

Cytosine permeation in Saccharomyces cerevisiae has been studied. Cytosine uptake is mediated by a permease which is also responsible for purines transport. The Km for the transport of various substrates of this permease have been determined. By means of appropriate selective techniques, mutants with altered Km and mutants lacking the permease have been selected. Cytosine transport is active and is inhibited by 2,4-dinitrophenol, an uncoupler of oxidative phosphorylation, and by N-ethylmaleimide, a reagent of--SH group. Internal labeled cytosine is chased by addition of unlabeled cytosine in the medium. These results support the hypothesis of a carrier-mediated transport, with reduced internal affinity, allowing the release and accumulation of cytosine in the inner compartment. The efflux of cytosine from cytosine permease-less cells has also been studied and shows first order kinetics. A diffusion coefficient of 5.7 per 10- minus 8 cm per S- minus 1 has been evaluated for this efflux.     

Familial juvenile hyperuricaemic nephropathy is not such a rare genetic metabolic purine disease in Britain

Renal disease is rare today in classic adult gout, and gout is rare in renal disease--especially in the young. Here we summarise studies in 158 patients from 31 kindreds diagnosed with familial juvenile hyperuricaemic nephropathy FJHN from a total of 230 kindred members studied in Great Britain. Some patients have been followed for up to 30 years, and allopurinol has ameliorated the progression of the renal disease in all 113 surviving members provided: They have been diagnosed and treated sufficiently early. Compliance with allopurinol treatment and diet has been as important as early recognition. Hypertension has been rigorously controlled. The use of oral contraceptives has been avoided, as has pregnancy in any female with a Glomelar Filtration Rate GFR <70 ml/min. The question arising is: Why is FJHN the most prevalent genetic purine disorder diagnosed in Britain? Is it a lack of awareness which needs to be improved Europe-wide?     

Choline acetyltransferase.

Acetylcholine is essential to neural function. It synthesis is catalyzed by choline acetyltransferase, the enzyme responsible for the acetylation of choline by acetyl coenzye A, a reaction favored slightly thermodymodynamically and not at all kinetically. An analytically pure enzyme still has not been obtained; however, method of purification have been greatly improved recently. Numerous inhibitors of the enzyme have been synthesized and their structure-action relationships examained. Evidence has been accumulated showing the essential involvement of an imidazole group in the active site of choline acetyltransferase. The literature regarding the controversial role to thiol groups in choline acetyltransferase is reviewed. Recently, derivatives of coenzyme A have been introduced as inhibitors of this enzyme and the specificity of coenzyme A binding has been examined. Possible mechanisms responsible for the control fo acetylcholine synthesis are discussed.     

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.     

Interferons: Purification and Physicochemical Aspects

Antiviral interferon activity in any one species can be exhibited by a variety of substances that differ in their physical and chemical properties, but the nature of these differences is not understood. Conditions that can lead to the formation of diverse types of interferons have been outlined. Reasons have been adduced why, for certain purposes, purification of interferons is desirable or even necessary, and examples have been presented to show how and to what extent this has been achieved. In spite of some very high purification factors, not a single interferon has been obtained as a pure substance. Therefore, all available knowledge of physical and chemical properties has been obtained by indirect means.     

Azotobacter vinelandii ferredoxin I: cloning, sequencing, and mutant analysis

The structure of Azotobacter vinelandii ferredoxin I (AvFdI) has been extensively characterized by a variety of techniques. Although its physiological function is unknown, it has long been implicated as being involved in electron donation to nitrogenase. Here we report that the AvFdI gene (fdxA) has been cloned from an EcoRI digest lambda library using a synthetic oligonucleotide probe and that its sequence has been determined. The amino acid sequence deduced from the DNA sequence is identical to the previously published protein sequence. Analysis of the promoter region indicates that AvFdI is not a nif specific gene product. A mutant of A. vinelandii has been constructed which is identical to the wild-type, at the DNA level, except that the fdxA gene has been interrupted by insertion of a kanamycin cartridge. This mutant, called LM100, does not synthesize AvFdI but does synthesize the Fe and MoFe proteins of nitrogenase and grows at wild-type rates under N2-fixing conditions. This demonstrates that AvFdI is not required for N2 fixation by A. vinelandii. There is a small acidic protein, which is present in wild-type A. vinelandii, whose level is dramatically increased in LM100. The nature of this protein is under further investigation.     

STUDIES ON PLANT GROWTH-REGULATING SUBSTANCES

Fifteen series of aryloxyacetic, α-aryloxy-propionic, -butyric and -isobutyric acids and the corresponding arylthio-analogues have been synthesized and their growth-regulating activity has been assessed in the tomato-leaf epinasty, wheat cylinder and the pea curvature tests. It is shown that in general arylthio-derivatives are less active than their aryloxy-analogues. Although for a cell elongation response the presence in the molecule of an a-hydrogen atom is usually necessary, three exceptions to this generalization have now been found. A lower activity in the 3:5-dichloro- compared with the 2:6-dichloro-compounds has been demonstrated. Evidence is presented to show that an ortho hydrogen atom in the nucleus is not an essential requirement for cell elongating activity as is postulated by other workers.     

The composition and structure of isolated chromosomes

1. The preparation of isolated chromosomes from liver, kidney, and pancreas has been described. 2. It has been shown that there is no gross cytoplasmic contamination in these preparations. 3. In a microscopic study of isolated chromosomes the same chromosomes have been found in different tissues of the same organism. Since individuality is one of the main characteristics of chromosomes, there can be little doubt that the preparations do, in fact, contain isolated chromosomes. 4. A quantitative study of staining with crystal violet shows that this basic dye competes with histone for the phosphoric acid groups of the DNA in chromosomes. The displacement of histone by protamine has been demonstrated. 5. Preparation of histone-free chromosomes has been described. Removal of histone does not affect the microscopic appearance of chromosomes. 6. The non-histone or residual protein has been prepared from histone-free chromosomes. The quantity of residual protein in a preparation of chromosomes is correlated with the amount of cytoplasm in the cells from which the chromosomes were prepared. 7. The microscopic appearance of chromosomes depends upon the association of DNA with residual protein. 8. Evidence has been given that in a chromosome there are two DNA-containing nucleoproteins; in one DNA is combined with histone, and in the other it is combined with residual protein.     

Kinetics of inhibition of acetylcholinesterase by spin labeled acetylcholine analogs.

A series of spin labeled acetycholine analogs, in which the number of methylene groups between the quaternary nitrogen and the alcohol oxygen ranged between 1-5, have been examined as inhibitors of electric eel acetylcholinesterase. Evidence is presented suggesting that inhibition of acetylocholinesterase by the spin labeled ACH analogs is due to the high affinity of these compounds for the enzyme, inhibition is competitive and reversible. It has been shown that complex formation is of major importance in the reaction between spin labeled ACH analogs and acetylcholinesterase. The acetylation step has been shown to occur by demonstrating that the leaving group is released as the reaction proceeds. Complex formation has been demonstrated by means of kinetic criteria. Kinetic parameter have been measured for the five compounds, and correlations with alkaline hydrolysis are disussed.