解剖学和形态学
麻醉学
听力与言语-语言病理学
行为科学
心脏和心血管系统
细胞和组织工程学
临床神经病学
危重症监护医学
牙科,口腔外科和医学
皮肤病学
急诊医学
内分泌学和新陈代谢
肠胃学和肝脏学
老人病学和老年医学
卫生保健科学和服务
血液学
免疫学
传染病
综合和补充性医学
医学伦理学
医学信息学
医学实验室技术
医学,全科和内科
医学,法律
医学,研究和试验
神经系统科学
护理
营养学和饮食学
产科医学和妇科医学
肿瘤学
眼科学
整形外科学
耳鼻喉科学
病理学
儿科学
周围血管疾病
药理学和药剂学
生理学
基本医疗保健
精神病学
公共、环境和职业卫生
放射学,核医学和医学成像
康复学
生殖生物学
呼吸系统
风湿病学
运动科学
外科学
毒理学
热带医学
泌尿学和肾脏学
病毒学
老年医学
健康政策和服务
心理学,临床
abstract::When simian virus 40 (SV40) infects host cells, the viral genes are expressed in two phases. Early in infection, the virus genome is transcribed and translated to yield two related proteins, 'large T' and 'small t' antigens. Later the rate of synthesis of the early messenger RNA falls and the viral genes coding for th...
journal_title:Nature
pub_type: 杂志文章
doi:10.1038/289810a0
更新日期:1981-02-26 00:00:00
abstract::T200, a major cell-surface glycoprotein on lymphoid cells, exists in several forms with different electrophoretic mobilities. These forms have been correlated with different classes of lymphoid cell. The smaller forms, with molecular weights (MWs) of congruent to 170,000 and 180,000 are found predominantly on T cells ...
journal_title:Nature
pub_type: 杂志文章
doi:10.1038/289681a0
更新日期:1981-02-19 00:00:00
abstract::In 1975-79, joint expeditions from Yale University and the Geological Survey of Pakistan (YGSP) recovered fossil lorisids in the Siwalik Group of Pakistan from four localities, spanning a period before 10 Myr ago to about 7 Myr ago. In three of the localities, only isolated teeth or fragments were found, whereas the f...
journal_title:Nature
pub_type: 历史文章,杂志文章
doi:10.1038/289585a0
更新日期:1981-02-12 00:00:00
abstract::Mineralocorticoid secretion is predominantly controlled by the octapeptide angiotensin II, which exerts trophic actions on the adrenal glomerulosa and acute regulatory effects on aldosterone biosynthesis. The trophic actions include stimulation of angiotensin II receptors and enzymes of the aldosterone biosynthetic pa...
journal_title:Nature
pub_type: 杂志文章
doi:10.1038/289507a0
更新日期:1981-02-05 00:00:00
abstract::In the frog Xenopus, the somatic-type 5S ribosomal RNA genes are active in all cells; the oocyte-type 5S genes are active in oocytes but not in somatic cells. A new method of native gel electrophoresis resolves the two types of 5S RNA which are of the same length but different sequence. When somatic nuclei were inject...
journal_title:Nature
pub_type: 杂志文章
doi:10.1038/289461a0
更新日期:1981-02-05 00:00:00
abstract::The ability to excise (repair) UV-induced pyrimidine dimers in Escherichia coli is not related to its ability to remove N-methyl-N'-nitro-N-nitrosoguanidine (MNNG)-induced O6-methylguanine (O6-MeG) from DNA. It was therefore surprising that certain xeroderma pigmentosum cell lines, deficient in dimer excision, were al...
journal_title:Nature
pub_type: 杂志文章
doi:10.1038/289417a0
更新日期:1981-01-29 00:00:00
abstract::Cyclosporin A (CSA) is a fungal metabolite which exerts profound effects on the immune system and has potential as a selective immuno-suppressive agent. Clinical trials with human renal allograft recipients have confirmed this potential but there have been disturbing reports of lymphoma in a significant number of pati...
journal_title:Nature
pub_type: 杂志文章
doi:10.1038/289300a0
更新日期:1981-01-22 00:00:00
abstract::Histamine secretion from mast cells may be inhibited by elevated intracellular levels of cyclic AMP and by several anti-allergic drugs. These compounds are claimed to act directly on the calcium-gating mechanism activated by the anaphylactic reaction, preventing influx of Ca2+ from the external environment and so bloc...
journal_title:Nature
pub_type: 杂志文章
doi:10.1038/289186a0
更新日期:1981-01-15 00:00:00
abstract::Flaviviruses, when complexed with antibody at subneutralizing concentrations, show enhanced replication in human and simian peripheral blood leukocytes (ref. 1, and J.S.M.P. and J.S.P., unpublished observations) and in P388 D1 and other macrophage cell lines. A comparable phenomenon has been demonstrated with alphavir...
journal_title:Nature
pub_type: 杂志文章
doi:10.1038/289189a0
更新日期:1981-01-15 00:00:00
abstract::Acyclovir (9-[2-hydroxyethoxymethyl]guanine or ACV) is a nucleoside analogue with considerable potential for the treatment of herpes simplex virus (HSV) infections in man. Two virus-coded enzymes are important in the mechanism of action of this drug: thymidine kinase (TK) which initiates its activation by converting i...
journal_title:Nature
pub_type: 杂志文章
doi:10.1038/289081a0
更新日期:1981-01-01 00:00:00
abstract::Certain mast cell products, including the tetrapeptides Ala-Gly-Ser-Glu (Ala4) and Val-Gly-Ser-Glu (Val4) of the eosinophil chemotactic factor of anaphylaxis (ECF-A) and histamine, are preferentially chemotactic for eosinophils in vitro. Amino acid substitutions or modifications of the ECF-A tetrapeptides may substant...
journal_title:Nature
pub_type: 杂志文章
doi:10.1038/289071a0
更新日期:1981-01-01 00:00:00
abstract::One of us has previously reported that treatment of the Keilin and Hartree heart-muscle preparation with 2,3-dimercaptopropanol (BAL), in the presence of air, leads to the complete inactivation of the succinate oxidase system with little if any effect on the activities of succinate dehydrogenase (until more than half ...
journal_title:Nature
pub_type: 杂志文章
doi:10.1038/288717a0
更新日期:1980-12-25 00:00:00
abstract::On the basis of their primary structure, the lysine-rich histones are a unified family of proteins. Each has an amino acid chain which falls into three distinct domains. Only the central domain (approximately 80 residues) is in a folded conformation. It is protected from trypsin digestion in chromatin and corresponds ...
journal_title:Nature
pub_type: 杂志文章
doi:10.1038/288675a0
更新日期:1980-12-25 00:00:00
abstract::Analogous to the progression of events in the opiate receptor-enkaphalin area, the first reports that benzodiazepines have selective and specific high-affinity binding sites in brain have stimulated a search for the endogenous 'ligand' or substance that might normally act at these sites. Braestrup and co-workers have ...
journal_title:Nature
pub_type: 杂志文章
doi:10.1038/288609a0
更新日期:1980-12-11 00:00:00
abstract::The study of the extent and basis of gene-enzyme variation has long been a principal concern of population genetics. Numerous surveys have indicated considerable amounts of genetic variation detectable in natural populations, with few exceptions. The variances of average heterozygosities (H) between species and among ...
journal_title:Nature
pub_type: 杂志文章
doi:10.1038/288580a0
更新日期:1980-12-11 00:00:00
abstract::Pathogenesis in sickle cell disease depends on the polymerization of deoxyhaemoglobin S into long fibres followed by 'gel' formation. The 'gelation' renders the affected erythrocytes less deformable than normal so that they obstruct the microvasculature and the 'gelation' process has been one of the targets for the de...
journal_title:Nature
pub_type: 杂志文章
doi:10.1038/288622a0
更新日期:1980-12-11 00:00:00
abstract::Collagen fibrils have been extensively studied by electron microscopy, but only scant evidence has yet been obtained about their transverse structure. A transverse pediodicity of about 40 or 80 A might be expected if the microfibril model (until recently the common preference) is correct, but little direct evidence fo...
journal_title:Nature
pub_type: 杂志文章
doi:10.1038/288410a0
更新日期:1980-11-27 00:00:00
abstract::A membrane receptor protein for asialoglycoproteins induces voltage-dependent increases in ion conductance across a lipid bilayer, probably reflecting penetration of the protein into the bilayer towards an electrically positive pole. In the presence of specific ligand for the receptor, this penetration leads to a 'tra...
journal_title:Nature
pub_type: 杂志文章
doi:10.1038/288333a0
更新日期:1980-11-27 00:00:00
abstract::Complementary DNAs for two distinct anglerfish somatostatin peptides (termed I and II) have been cloned in bacterial plasmids and sequenced. The nucleotide sequence for somatostatin I encodes a large percursor peptide (molecular weight 13,300) in which the somatostatin hormones is at the carboxyl terminus. The predict...
journal_title:Nature
pub_type: 杂志文章
doi:10.1038/288137a0
更新日期:1980-11-13 00:00:00
abstract::Chronic administration of several chemical carcinogens to laboratory animals induces a variety of tumours which arise from specific cell populations within the liver. In the rat, diethylnitrosamine induces hepatocellular carcinomas, dimethylnitrosamine induces both angiosarcomas and hepatocellular carcinomas, vinyl ch...
journal_title:Nature
pub_type: 杂志文章
doi:10.1038/288185a0
更新日期:1980-11-13 00:00:00
abstract::The enkephalins Met-enkephalin and Leu-enkephalin were first isolated from porcine brain by Hughes and co-workers. We have recently isolated from bovine adrenals another enkephalin with the structure Tyr-Gly-Gly-Phe-Met-Arg-Phe, or Met-enkephalin-Arg6-Phe7 (ref. 2). We report here that this new heptapeptide is found i...
journal_title:Nature
pub_type: 杂志文章
doi:10.1038/288088a0
更新日期:1980-11-06 00:00:00
abstract::Over the last twenty years classical views of how compound eyes work optically have undergone a series of overhauls. Exner's central concept of an optically inhomogeneous lens cylinder has survived, and such devices are now made commercially. He was wrong, however, about some crustacean eyes. They produce images by a ...
journal_title:Nature
pub_type: 杂志文章,评审
doi:10.1038/287681a0
更新日期:1980-10-23 00:00:00
abstract::The regular occurrence of a peak due to an unidentified substance (X) in the gas chromatographic traces obtained from phenolic extracts of urine from human pregnant and non-pregnant females has been reported. The biphasic excretion of X with maxima in the luteal phase of the ovulatory cycle and relatively high levels ...
journal_title:Nature
pub_type: 杂志文章
doi:10.1038/287738a0
更新日期:1980-10-23 00:00:00
abstract::The purified p21src protein of Harvey sarcoma virus shows a guanine nucleotide-binding activity and, in addition, at elevated temperature an autophosphorylating activity at a threonine residue using as phosphoryl donor GTP or dGTP but not ATP or dATP. These biochemical activities are unique among those associated with...
journal_title:Nature
pub_type: 杂志文章
doi:10.1038/287686a0
更新日期:1980-10-23 00:00:00
abstract::The assembly of microtubules has been investigated by time-resolved X-ray diffraction using synchrotron radiation. The small-angle scattering becomes visible within seconds and thus enables study of the structural transitions of the protein aggregates during assembly from their subunits in solution. The X-ray pattern ...
journal_title:Nature
pub_type: 杂志文章
doi:10.1038/287595a0
更新日期:1980-10-16 00:00:00
abstract::Individual mammals have the capacity to express at least one million distinct antigen binding specificities, implying a high degree of structural heterogeneity in the variable heavy and light chain (VH and VL) portions of the antibody molecules. Studies of higher vertebrate species suggest that this heterogeneity is c...
journal_title:Nature
pub_type: 杂志文章
doi:10.1038/287639a0
更新日期:1980-10-16 00:00:00
abstract::Dopamine (DA) has largely been ignored in considering possible mechanisms underlying the therapeutic effects of tricyclic anti-depressants (TCA). Most previous work done has focused on the ability of some TCAs to block the in vitro re-uptake of DA--an effect which unfortunately requires very high doses. Recently, howe...
journal_title:Nature
pub_type: 杂志文章
doi:10.1038/287451a0
更新日期:1980-10-02 00:00:00
abstract::The glutamate dehydrogenase gene of Escherichia coli has been cloned into broad host-range plasmids and can complement glutamate synthase mutants of Methylophilus methylotrophus. Assimilation of ammonia via glutamate dehydrogenase is more energy-efficient than via glutamate synthase, thus the recombinant organism conv...
journal_title:Nature
pub_type: 杂志文章
doi:10.1038/287396a0
更新日期:1980-10-02 00:00:00
abstract::Double-stranded DNA copies of the RNA gene coding for the haemagglutinin glycoproteins from human H2 and H3 pandemic strains of influenza virus have been cloned. DNA sequence analysis provides the first reported complete nucleotide sequence of an H2 haemagglutinin gene and a partial sequence (45%) of the H3 gene. The ...
journal_title:Nature
pub_type: 杂志文章
doi:10.1038/287301a0
更新日期:1980-09-25 00:00:00
abstract::Recent studies have suggested that actomyosin threads may provide a useful model for studying the properties of contractile systems. The development of highly sensitive positional feedback transducers has enabled the properties of these threads to be measured reproducibly. Potential applications include such systems a...
journal_title:Nature
pub_type: 杂志文章
doi:10.1038/287338a0
更新日期:1980-09-25 00:00:00
abstract::Since the pioneering work of the Millers it has become clear that most chemical carcinogens require metabolism to reactive electrophiles and then exhibit their carcinogenic potential by reacting chemically with, and modifying, cellular macromolecules. At first modification of proteins was considered most likely to be ...
journal_title:Nature
pub_type: 杂志文章
doi:10.1038/287244a0
更新日期:1980-09-18 00:00:00
abstract::Chick embryo fibroblasts (CEF) infected with avian sarcoma virus become rapidly transformed as a result of expression of the viral src gene in the form of a single polypeptide of molecular weight 60,000 (pp60src) with protein kinase activity and suggested preferential association with the plasma membrane. Studies with...
journal_title:Nature
pub_type: 杂志文章
doi:10.1038/287241a0
更新日期:1980-09-18 00:00:00
abstract::Anti-inflammatory glucocorticoids inhibit prostaglandin (PG) biosynthesis by preventing arachidonic acid release from phospholipids rather than inhibiting the cyclooxygenase. As in other cells, this steroid action depends on receptor occupation and de novo protein/RNA biosynthesis. We have previously shown in guinea p...
journal_title:Nature
pub_type: 杂志文章
doi:10.1038/287147a0
更新日期:1980-09-11 00:00:00
abstract::Although freeze-fracture electron microscopy is normally analysed with the presumption that particles represent proteins embedded within the membrane, particles which appeared to represent inverted lipid micelles within membranes have been reported. I have now confirmed the occurrence of particles in protein-free lipo...
journal_title:Nature
pub_type: 杂志文章
doi:10.1038/287166a0
更新日期:1980-09-11 00:00:00
abstract::The extensive literature on the origin of the ratites focuses mainly on three questions: are the ratites mono- or polyphyletic, did they evolve from flying ancestors, and are they primitive or advanced? Opinion tends to accept a common descent from flying ancestors for the large ratites (for a summary of ideas see ref...
journal_title:Nature
pub_type: 杂志文章
doi:10.1038/287084a0
更新日期:1980-09-04 00:00:00
abstract::Sodium channels in plasma membranes can be blocked by a large variety of toxins and local anaesthetics. This property, however, is not confined to relatively large molecules. For instance, extracellularly applied small ions like hydrogen may also prevent the passive transport of permeant cations across open Na+ channe...
journal_title:Nature
pub_type: 杂志文章
doi:10.1038/287062a0
更新日期:1980-09-04 00:00:00
abstract::We report here the identification of human cell-surface glycoprotein with unusual and interesting properties. We initially detected this glycoprotein on the surface of cultured human haematopoietic cell lines by means of a monoclonal antibody. Although it is expressed on all cultured human haematopoietic cell lines te...
journal_title:Nature
pub_type: 杂志文章
doi:10.1038/286888a0
更新日期:1980-08-28 00:00:00
abstract::The insulins of New World hystricomorph rodents exhibit many novel amino acid changes in primary structure when compared with other mammalian insulins. These changes give rise to unusual properties (low potency, failure to self-associate) not shared by other naturally-occurring insulins. We report here on the primary ...
journal_title:Nature
pub_type: 杂志文章
doi:10.1038/286822a0
更新日期:1980-08-21 00:00:00
abstract::Calcium permeability of basophil and mast cell membranes is stimulated on allergen binding to its specific membrane-bound IgE. This entry of Ca2+ ions into the cell triggers the degranulation and secretion process. Disodium cromoglycate (cromolyn DSCG), the disodium salt of 1,3-bis(-2-carboxychromon-5-yloxy)-2-hydroxy...
journal_title:Nature
pub_type: 杂志文章
doi:10.1038/286722a0
更新日期:1980-08-14 00:00:00
abstract::The contractile proteins of adult skeletal and cardiac muscle tissue are very similar. Some of these proteins are identical in amino acid sequence or differ only slightly. Various structural studies have shown that the heavy and light chains of myosin are also homologous in skeletal and cardiac muscles. In developing ...
journal_title:Nature
pub_type: 杂志文章
doi:10.1038/286731a0
更新日期:1980-08-14 00:00:00