首页 | 本学科首页   官方微博 | 高级检索  
相似文献
 共查询到20条相似文献,搜索用时 62 毫秒
1.
The different invasive and noninvasive diagnostic tests for Helicobacter pylori have been applied mainly in emerging countries. Molecular methods have been developed, especially a test for detection of H. pylori and its clarithromycin resistance directly from stools. The long-term effects of eradication on histologic lesions have been studied in a meta-analysis and the prognostic value of post-treatment in gastric mucosa-associated lymphoid tissue lymphoma has been assessed. An operating link for gastritis assessment (the OLGA staging) has also been published. Attempts to simplify the urea breath test protocol have been made, and new stool antigen tests have been proposed and compared to those previously available.  相似文献   

2.
Humoral and cellular mechanisms of defense have been described for cephalopods, a relatively advanced group of mollusks. Typical of other mollusks, cephalopod agglutinins are the most documented component of humoral immunity. Lectins, which have agglutinating properties, have been described and characterized from octopuses. Agglutinins from cephalopod hemolymph have also been shown to agglutinate a variety of vertebrate red blood cells, as well as potential bacterial pathogens. Hemocytes are the primary component of cellular immunity. Although the hemocyte role in phagocytosis has been extensively studied in other mollusks, the mechanisms of phagocytosis have not been described extensively for cephalopods. Cephalopod hemocytes have phagocytic capabilities and may function in encapsulation and neutralization of foreign substances; however, the effects of environmental factors and the full extent of phagocytic capabilities of cephalopod hemocytes have not been reported. Hemocytes from cephalopods have a role in wound healing and inflammation which have been reported in detail by several investigators.  相似文献   

3.
1. Platelets have been isolated from plasma and their surface glycoconjugates radioactively-labelled using galactose oxidase and NaB3H4. 2. Conditions have been defined for optimal labelling of glycoproteins and a membrane fraction enriched in plasma membrane has been prepared and characterized by sodium dodecyl sulphate/polyacrylamide-gel electrophoresis. 3. Desialylated glycoproteins that act as receptors to peanut agglutinin and lentil lectin have been purified from a detergent extract of plasma membrane. 4. Two glycosylated polypeptides that are able to bind to the surfaces of platelets have been identified and some characteristics of the binding have been investigated.  相似文献   

4.
In this, a preliminary report, the advantages and disadvantages of upper lobe lobectomy and concomitant thoracoplasty in tuberculosis have been summarized. There has been no undue increase in the operative hazard, there have been no complications, and the immediate results have been entirely satisfactory.Twenty-six patients were subjected to a combined operation (17 upper lobectomy-thoracoplasty and nine pneumonectomy-thoracoplasty) with one postoperative death. Indications for primary lobectomy have been discussed. The technique of resection and concomitant thoracoplasty has been briefly described.  相似文献   

5.
Gas chromatography mass spectrometry has been used for over a decade for the determination of the amino acid sequences of fragment peptides derived from larger parent molecules. The majority of these fragments have from four to seven residues and several different methods of derivatization have been devised. Few reports have been published in which similar techniques have been used for the quantification of such peptides, but there is a growing list of small peptides which have been shown to have biological activity in their own right. This report is concerned with the development of a gas chromatographic mass spectrometric assay for the two eosinophil chemotactic peptides, Val-Gly-Ser-Glu and Ala-Gly-Ser-Glu, which appear to have a role to play in the course of the inflammatory process in skin disorders.  相似文献   

6.
For 30 days Wistar rats have been kept under conditions of hypokinesia. Using stereological methods, the volume and surface density of muscle fibers, microcirculatory bed and connective tissue components have been defined, and volumetric and surface--volume ratios of parenchymal and stromal structures have been calculated. Intracellular stereological parameters of the cardiac myocytes have been studied. Three-dimensional parameters in the parenchymatous-stromal interrelations of the atrophying myocardium accompanied with a deep rearrangement of the intracellular architectonics have been determined, as well as certain destructive changes of the cardiac myocyte ultrastructures. Such a treatment as a decreased functional loading is demonstrated to be the cause of cardiomyocytic lesions.  相似文献   

7.
In this, a preliminary report, the advantages and disadvantages of upper lobe lobectomy and concomitant thoracoplasty in tuberculosis have been summarized. There has been no undue increase in the operative hazard, there have been no complications, and the immediate results have been entirely satisfactory.Twenty-six patients were subjected to a combined operation (17 upper lobectomy-thoracoplasty and nine pneumonectomy-thoracoplasty) with one postoperative death.Indications for primary lobectomy have been discussed.The technique of resection and concomitant thoracoplasty has been briefly described.  相似文献   

8.
The aliphatic 1H-NMR spectrum of the kringle 4 domain of human plasminogen has been studied via two-dimensional chemical shift correlated (COSY) and nuclear Overhauser correlated (NOESY) experiments at 300 MHz and 620 MHz. A number of aliphatic proton spin systems have been identified and several definite assignments have been made. This was mainly achieved by comparison of the human kringle 4 spectrum with spectra of the porcine, bovine and chicken homologs and also with that of the kringle 1 from human plasminogen on which we have reported previously. The three valyl and two leucyl residues of human kringle 4 have been assigned. The eleven threonyl spin systems have been identified via a RELAYED-COSY experiment and Thr17 has been assigned. The three alanyl spin systems have been identified and assigned. Six seryl spin systems have been identified and the signals from the seven glycyl residues of human kringle 4 have been located with Gly45 assigned. Furthermore, 24 AMX spin systems have been mapped in the COSY spectrum of human kringle 4 and H alpha-H beta,beta' spin systems of Tyr2, Tyr41, Tyr50, Tyr74, Trp25 and Trp62 have been assigned. From the spectrum of a deglycosylated chicken homolog, the epsilon-methyl singlets of Met28 and Met48 have been assigned. Finally, ligand effects on selected aliphatic resonances were observed which could be analyzed in terms of residues likely to neighbor the kringle lysine-binding site.  相似文献   

9.
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.  相似文献   

10.
Phosphorylase has been fractionated during development and germination of seeds of smooth and wrinkled-seeded peas. The total phosphorylase levels have been compared. In addition, a number of other pea tissues and other legumes have been examined. Some kinetic properties of the two enzymes present have been measured. Both enzymes have been further purified by affinity chromatography on Sepharose 4B-starch columns and by sequential gel filtration in the absence and presence of amylopectin. The MW and sub-unit structures of the two enzymes have been examined and their possible roles discussed.  相似文献   

11.
The presence or absence of a chemoreceptive capacity in marine mammals has drawn relatively little attention from the research community outside the Soviet Union. Toothed whales are typically labelled anosmic (lacking a sense of smell) since they do not have the peripheral olfactory structures typically associated with terrestrial mammals. Baleen whales are known to possess reduced olfactory tracts; their olfactory bulbs also may be reduced or absent. Although the neural structures that mediate taste in terrestrial mammals have been reported to be present in both groups of whales, cetaceans have been considered to have a poor sense of taste because typical mammalian taste receptors have been thought to be absent. Soviet researchers, however, recently have reported that gustatory receptors are present on some cetacean tongues and that the tongue of Tursiops truncatus appear to be well innervated. These workers also have been conducting investigations which seem to be aimed at describing a specialized gustatory capability in cetaceans. No experimental work has been reported by Western scientists. Little work has been done by either Western or Soviet researchers with regard to chemoreception among the other orders of marine mammals (Pinnipedia, Carnivora and Sirenia). Pinnipedia are typically labelled microsmatic (having a poor sense of smell); research has been restricted to histological examination of the nasal pathways, and neural anatomy. Sea otters are credited with a keen sense of smell, but no quantitative work has been reported. The chemosensory abilities of Sirenia remain unknown. The tongues of non-cetacean marine mammals have been histologically examined and found to resemble those of terrestrial mammals. No other investigations of gustation in non-cetacean marine mammals have been reported.  相似文献   

12.
The solution conformations of thyrotrophin-releasing hormone (TRH), a biologically-active tripeptide, have been predicted computationally using a method which represents solution effects as a dielectric continuum surrounding the molecule throughout energy minimisation; this is described as the reaction field contribution. The predicted conformations have been compared with previous experimental and theoretical studies. Favoured conformations of TRH under other simulated conditions have also been examined, including the behaviour of the cis isomer, and have been related to possible interactions with intermediates and with specific receptors. The relevance of these predictions to the design of biologically-active analogues of TRH has been analysed.  相似文献   

13.
14.
The drug Bitter Aloes has been used for several thousands of years because of its purgative properties and later several species of the plant have been cultivated for horticultural interest. In addition, many more local therapeutic properties have been recorded. Research has been largely directed towards the physiologically active components during the 50s and 60s. Extensions to this work in the last decade have been made in Germany, Japan and South Africa. Compounds have been characterized from the dried exudate prepared for drug purposes and from a few species. A number of anthraquinones have been recognized both in the free state and as glycosides. Other compounds with phenolic groups include chromones and a phenyl-pyranone. Chromatographic methods have been developed for recognizing some of these compounds and estimating the levels of those of pharmacological interest. Distribution of some of the compounds among a number of species is described showing that among some groups it has taxonomic significance. The biology of secretion and exudation from Aloë leaves remains largely unknown although fragmentary evidence points to interesting and potentially useful activity in some of the components.  相似文献   

15.
Small, non-coding bacterial RNAs (sRNAs) have been shown to regulate a plethora of biological processes. Up until recently, most sRNAs had been identified and characterized in E. coli. However, in the past few years, dozens of sRNAs have been discovered in a wide variety of bacterial species. Whereas numerous sRNAs have been isolated or detected through experimental approaches, most have been identified in predictive bioinformatic searches. Recently developed computational tools have greatly facilitated the efficient prediction of sRNAs in diverse species. Although the number of known sRNAs has dramatically increased in recent years, many challenges in the identification and characterization of sRNAs lie ahead.  相似文献   

16.
cDNA clones encoding uricase have been isolated from a rabbit liver cDNA library. The nucleotide sequences of the cDNAs have been determined and those of the rat uricase cDNA have been revised. In all three uricases, the carboxy-terminal tripeptides are Ser-Arg/Lys-Leu sequences, which have recently been suggested as an essential element of peroxisomal targetting signals for many but not all peroxisomal proteins.  相似文献   

17.
Quadruplex nucleic acids can be formed at the ends of eukaryotic chromosomes. Their formation and stabilisation by appropriate small molecules can be used as a means of inhibiting the telomere maintenance functions of telomerase in human cancer cells. The crystal structures have been determined for a number of complexes between these small molecules and human telomeric DNA and RNA quadruplexes. The detailed structural characteristics of these complexes have been surveyed here and the variations in conformation for the TTA and UUA loops have been explored. Loop conformations have been classified in terms of a number of discrete types and their distribution among the crystal structures. Sugar conformation and backbone angles have also been examined and trends highlighted. One particular loop class has been found to be most prevalent. Implications for in particular, rational drug design, are discussed.  相似文献   

18.
The results of cytogenetic examination carried out in 255 couples with a history of infertility have been analysed. Chromosomal aberrations have been detected in 15 examinations (6.7%) with predominance of translocations (mutual - 3.6%; Robertson' - 1.3%). Identified aberrations have been noted in 9 women and 6 men. The obtained results have been analysed in relation to the number of abortions, dead and live newborn babies with inherited abnormalities. It was found that the incidence of chromosomal aberrations increases with the number of the spontaneous abortions in anamnesis. Such aberrations have also been more frequent in the families in which spontaneous abortions have been accompanied by other fertility disorders.  相似文献   

19.
A review of the different publications dealing with melatonin in humans shows that this field has been very active in the last few years. Normative melatonin values have been defined. Various relationships between melatonin and other traits have been studied, such as sleep, circadian rhythm, surgical stress and anaesthesia. Age-related melatonin studies and melatonin during depression and other psychiatric disorders have been reviewed. Finally, some studies have been performed to use melatonin as a medication for sleep disturbance in depression, for jet-lag and as a skin protector for ultraviolet light.  相似文献   

20.
Several Wolf-Hirschhorn syndrome patients have been studied, mouse models for a few candidate genes have been constructed and two WHS critical regions have been postulated, but the molecular basis of the syndrome remains poorly understood.  相似文献   

设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号