Experientia最新文献_第10页

Purification and some properties of hemagglutinin from the Myxomycete, Physarum polycephalum. 多头绒泡菌黏菌血凝素的纯化及其性质研究。

Experientia Pub Date : 1996-06-15 DOI: 10.1007/BF01969725

M Yokota, K Nitta

引用次数: 2

The accessory gland proteins in male Drosophila: structural, reproductive, and evolutionary aspects. 雄性果蝇的副腺蛋白:结构、生殖和进化方面。

Experientia Pub Date : 1996-06-15 DOI: 10.1007/BF01969718

P S Chen

引用次数: 47

Conservation, evolution, and specificity in cellular control by protein phosphorylation. 蛋白质磷酸化在细胞控制中的保护、进化和特异性。

Experientia Pub Date : 1996-05-15 DOI: 10.1007/BF01919314

H W Hofer

引用次数: 5

Some thoughts on the importance of insulin in the regulation of the blood glucose level. 关于胰岛素在调节血糖水平中的重要性的一些思考。

Experientia Pub Date : 1996-05-15 DOI: 10.1007/BF01919310

E A Newsholme, G Dimitriadis

引用次数: 6

Hyperinsulinemia, hyperproinsulinemia and insulin resistance in the metabolic syndrome. 代谢综合征中的高胰岛素血症、高胰岛素原血症和胰岛素抵抗。

Experientia Pub Date : 1996-05-15 DOI: 10.1007/BF01919311

J Schrezenmeir

{"title":"Hyperinsulinemia, hyperproinsulinemia and insulin resistance in the metabolic syndrome.","authors":"J Schrezenmeir","doi":"10.1007/BF01919311","DOIUrl":"https://doi.org/10.1007/BF01919311","url":null,"abstract":"For better comprehension of the metabolic syndrome, it is necessary to differentiate the effect of insulin on glucose metabolism on the one hand, and on other metabolic activities on the other hand. Whereas glucose utilization is affected by insulin resistance, the effect of insulin on lipid metabolism, ion and aminoacid transport does not seem to be diminished. Lipid metabolism, however, seems to play a crucial role in the induction of the vicious cycle. Increased energy and fat ingestion may be due to an increased number of galanin secreting cells in the hypothalamus. The excessive fat intake results in an increased rate of release of insulin and increased influx of triglycerides into the blood. From these triglycerides an excess of free fatty acids is released by the action of lipoprotein lipase. The increased plasma free fatty acid level then results in insulin resistance affecting glucose metabolism. Also, these free fatty acids may impair the secretion of insulin. Induction of insulin resistance results in higher glucose levels, which may cause hyperinsulinemia. Hyperinsulinemia maintains the elevation of triglycerides. When diabetes becomes overt and elevated glucose levels prevail, the hyperinsulinism acts on the metabolic pathways which are still sensitive to insulin, namely lipid metabolism, aminoacid transport and ion transport.","PeriodicalId":12087,"journal":{"name":"Experientia","volume":"52 5","pages":"426-32"},"PeriodicalIF":0.0,"publicationDate":"1996-05-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1007/BF01919311","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"19618513","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 30

Metabolic regulation--physiological and medical aspects. 代谢调节——生理和医学方面。

Experientia Pub Date : 1996-05-15 DOI: 10.1007/BF01919305

G Wegener, U Krause, E A Newsholme

引用次数: 10

Spermatozoa: models for studying regulatory aspects of energy metabolism. 精子:研究能量代谢调节方面的模型。

Experientia Pub Date : 1996-05-15 DOI: 10.1007/BF01919321

G Kamp, G Büsselmann, J Lauterwein

{"title":"Spermatozoa: models for studying regulatory aspects of energy metabolism.","authors":"G Kamp, G Büsselmann, J Lauterwein","doi":"10.1007/BF01919321","DOIUrl":"https://doi.org/10.1007/BF01919321","url":null,"abstract":"Spermatozoa are highly specialized cells, and they offer advantages for studying several basic aspects of metabolic control such as the role of adenosine triphosphate-(ATP)-homeostasis for cell function, the mechanisms of fatigue and metabolic depression, the metabolic channelling through the cytoplasm and the organization and regulation of glycolytic enzymes. Spermatozoa of four species with different reproductive modes are introduced and the first results are presented: Spermatozoa of the marine worm Arenicola marina are well adapted to external fertilization in sea water with fluctuating oxygen tension: they are motile for several hours in oxygen-free sea water, even when the ATP level is dramatically reduced. Anaerobic ATP production occurs by alanine, acetate and propionate fermentation probably by the same pathways known from somatic cells of this species. Under aerobic conditions the phosphagen system might function like a shuttle for energy-rich phosphate from mitochondria to the dynein-ATPases. Storage of turkey and carp spermatozoa for several hours without exogenous substrates and oxygen results in the degradation of phosphocreatine and ATP to inorganic phosphate and adenosine monophosphate (AMP), respectively. Despite low energy charges, stored spermatozoa of both species are capable of progressive movements. In carp spermatozoa fatigue of motility is not accompanied by the dramatic acidosis one discusses as an important effect in muscle fatigue. Energy metabolism of boar spermatozoa is typically based on glycolysis consuming extracellular carbohydrates and producing lactate and protons. The sperm seem to tolerate low intracellular pH (< 6.5). The lack of a phosphagen system (no energy shuttle from mitochondria to the distal dynein-ATPases) is probably compensated by a high glycolytic ATP-production in the mitochondria-free piece of the flagellum.","PeriodicalId":12087,"journal":{"name":"Experientia","volume":"52 5","pages":"487-94"},"PeriodicalIF":0.0,"publicationDate":"1996-05-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1007/BF01919321","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"19619076","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 72

Control of adenine nucleotide metabolism and glycolysis in vertebrate skeletal muscle during exercise. 运动时脊椎动物骨骼肌腺嘌呤核苷酸代谢和糖酵解的控制。

Experientia Pub Date : 1996-05-15 DOI: 10.1007/BF01919306

U Krause, G Wegener

{"title":"Control of adenine nucleotide metabolism and glycolysis in vertebrate skeletal muscle during exercise.","authors":"U Krause, G Wegener","doi":"10.1007/BF01919306","DOIUrl":"https://doi.org/10.1007/BF01919306","url":null,"abstract":"The turnover of adenosine triphosphate (ATP) in vertebrate skeletal muscle can increase more than a hundredfold during high-intensity exercise, while the content of ATP in muscle may remain virtually unchanged. This requires that the rates of ATP hydrolysis and ATP synthesis are exactly balanced despite large fluctuations in reaction rates. ATP is regenerated initially at the expense of phosphocreatine (PCr) and then mainly through glycolysis from muscle glycogen. The increased ATP turnover in contracting muscle will cause an increase in the contents of adenosine diphosphate (ADP), adenosine monophosphate (AMP) and inorganic phosphate (P(i)), metabolites that are substrates and activators of regulatory enzymes such as glycogen phosphorylase and phosphofructokinase. An intracellular metabolic feedback mechanism is thus activated by muscle contraction. How muscle metabolism is integrated in the intact body under physiological conditions is not fully understood. Common frogs are suitable experimental animals for the study of this problem because they can readily be induced to change from rest to high-intensity exercise, in the form of swimming. The changes in metabolites and effectors in gastrocnemius muscle were followed during exercise, post-exercise recovery and repeated exercise. The results suggest that glycolytic flux in muscle is modulated by signals from outside the muscle and that fructose 2,6-bisphosphate is a key signal in this process.","PeriodicalId":12087,"journal":{"name":"Experientia","volume":"52 5","pages":"396-403"},"PeriodicalIF":0.0,"publicationDate":"1996-05-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1007/BF01919306","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"19618601","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 15

Is there a critical tissue oxygen tension for bioenergetic status and cellular pH regulation in solid tumors? 在实体瘤中是否存在生物能量状态和细胞pH调节的临界组织氧张力?

Experientia Pub Date : 1996-05-15 DOI: 10.1007/BF01919317

P Vaupel

{"title":"Is there a critical tissue oxygen tension for bioenergetic status and cellular pH regulation in solid tumors?","authors":"P Vaupel","doi":"10.1007/BF01919317","DOIUrl":"https://doi.org/10.1007/BF01919317","url":null,"abstract":"Bioenergetic and metabolic status have been correlated with tissue oxygenation in murine fibrosarcomas (FSaII) of varying sizes (44-600 mm3). Ratios of beta-nucleoside triphosphates to inorganic phosphate (beta NTP/P) and phosphocreatine to inorganic phosphate (PCr/P(i)) ratios derived from 31P nuclear magnetic resonance spectroscopy (NMR) were positively correlated to median tissue O2 tension (pO2) values using O2-sensitive needle electrodes. pH declined during growth with intracellular acidosis being evident in tumors > 350 mm3. Whereas lactic acid formation greatly contributed to this decline in small and medium-sized tumors, adenosine triphosphate (ATP) hydrolysis and slowing down of the activities of pumps involved in cellular pH regulation seem to be major factors responsible for intracellular acidification in bulky tumors. PCr levels decreased at an early growth stage, whilst ATP concentrations dropped in bulky malignancies only, coinciding with a decrease in adenylate energy charge and a substantial rise in the levels of total P(i). On average, median pO2 values of ca. 10 mmHg represent a critical threshold for energy metabolism. At higher median O2 tensions, levels of ATP, phosphomonoester (PME) and total P(i) were relatively constant. This coincided with intracellular alkalosis or neutrality and stable adenylate ratios. On average, median pO2 values < 10 mmHg coincided with intracellular acidosis, ATP depletion, a drop in energy charge and rising P(i) levels.","PeriodicalId":12087,"journal":{"name":"Experientia","volume":"52 5","pages":"464-8"},"PeriodicalIF":0.0,"publicationDate":"1996-05-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1007/BF01919317","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"19618518","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 14

Flying insects: model systems in exercise physiology. 飞虫:运动生理学的模型系统。

Experientia Pub Date : 1996-05-15 DOI: 10.1007/BF01919307

G Wegener

{"title":"Flying insects: model systems in exercise physiology.","authors":"G Wegener","doi":"10.1007/BF01919307","DOIUrl":"https://doi.org/10.1007/BF01919307","url":null,"abstract":"Insect flight is the most energy-demanding exercise known. It requires very effective coupling of adenosine triphosphate (ATP) hydrolysis and regeneration in the working flight muscles. 31P nuclear magnetic resonance (NMR) spectroscopy of locust flight muscle in vivo has shown that flight causes only a small decrease in the content of ATP, whereas the free concentrations of inorganic phosphate (Pi), adenosine diphosphate (ADP) and adenosine monophosphate (AMP) were estimated to increase by about 3-, 5- and 27-fold, respectively. These metabolites are potent activators of glycogen phosphorylase and phosphofructokinase (PFK). Activation of glycolysis by AMP and Pi is reinforced synergistically by fructose 2,6-biphosphate (F2,6P2), a very potent activator of PFK. During prolonged flight locusts gradually change from using carbohydrate to lipids as their main fuel. This requires a decrease in glycolytic flux which is brought about, at least in part, by a marked decrease in the content of F2,6P2 in flight muscle (by 80% within 15 min of flight). The synthesis of F2,6P2 in flight muscle can be stimulated by the nervous system via the biogenic amine octopamine. Octopamine and F2,6P2 seem to be part of a mechanism to control the rate of carbohydrate oxidation in flight muscle and thus function in the metabolic integration of insect flight.","PeriodicalId":12087,"journal":{"name":"Experientia","volume":"52 5","pages":"404-12"},"PeriodicalIF":0.0,"publicationDate":"1996-05-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1007/BF01919307","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"19618602","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 81