共查询到20条相似文献,搜索用时 406 毫秒
1.
Summary Plasma estradiol-17 (E2) concentration was measured in 5 adult non-pregnant rabbits each in 3 different seasons (January, April and September). Blood samples were taken from each rabbit every other day. There was a considerable variation in plasma E2 levels from one sampling day to another, irrespective of the season. The pattern of variation in E2 levels in individual rabbits tended to be cyclic and this cycle was roughly of the order of 8 days. There was no correlation between changes in E2 levels and those in the vaginal appearance. *** DIRECT SUPPORT *** A2025089 00013This study was supported by the Ford Foundation, and the Swedish Medical Research Council (project No. 4781). 相似文献
2.
Differences in the tissue content of prothymosin during the early postnatal development of male and female rats are reported. Thymus and spleen have been found to contain significantly higher amounts of prothymosin in the newborn and prepubertal animals, as compared to adults, whereas liver has been found to contain low levels of prothymosin throughout development. These findings indicate a functional association of prothymosin with the proliferating lymphoid tissues of the young rat. 相似文献
3.
Summary An investigation of 104 natural graphites shows in most of the samples a content <1 ppm mercury (Hg). An emissionspectrochemical method was used by the doubleare fromL. H. Ahrens. There are samples in the mine-ralogical collections with contents >10 ppm Hg, if metallic mercury is present in these collections. 相似文献
4.
Catherine Vidal 《Cellular and molecular life sciences : CMLS》1980,36(1):77-78
Summary In decorticated unanaesthetized and paralysed cats, locomotor bursting may develop spontaneously on hindlimb motor nerves. In defined experimental conditions, the amplitude of successive rhythmic bursts may fluctuate periodically as if a secondary oscillation was superimposed upon the basic locomotor rhythm. The possible meaning of such amplitude fluctuation is discussed in connection with present data about the generation of locomotion. 相似文献
5.
Darinka Koraćević 《Cellular and molecular life sciences : CMLS》1975,31(1):26-27
Résumé Une seule injection d'éthionine (400 mg/kg) provoque une augmentation significative de l'activité de la cystathionine -synthase du foie de rat. La méthionine empêche l'effect de l'éthionine, tandis que l'actinomycine D, le cycloheximide, la méthionine sulfoximine, la méthionine sulfona et l'ATP ne le modifient pas. In vitro, l'éthionine n'a aucune influence sur l'activité de la cystathionine synthase hépatique.
This work was supported by the Serbian Medical Research Foundation. 相似文献
This work was supported by the Serbian Medical Research Foundation. 相似文献
6.
The goal of periodontal regenerative therapy is to predictably restore the tooth’s supporting periodontal tissues and form a new connective tissue attachment of periodontal ligament (PDL) fibers and new alveolar bone. Periostin is a matricellular protein so named for its expression primarily in the periosteum and PDL of adult mice. Its biological functions have been widely studied in areas such as cardiovascular physiology and oncology. Despite being initially identified in the dental tissues and bone, investigations of Periostin functions in PDL and alveolar-bone-related physiopathology are less abundant. Recently, several studies have suggested that Periostin may be an important regulator of periodontal tissue formation. By promoting collagen fibrillogenesis and the migration of fibroblasts and osteoblasts, Periostin might play a pivotal part in regeneration of the PDL and alveolar bone following periodontal surgery. The aim of this article is to provide an extensive review of the implications of Periostin in periodontal tissue biology and its potential use in periodontal tissue regeneration. 相似文献
7.
Summary The effect of N-methyl-N-nitro-N-nitrosoguanidine (MNNG) on epithelial differentiation of fetal rat forestomach was investigated in organ culture. When forestomach tissues removed from 16.5-day fetuses were treated with 5 g and 3 g of MNNG per ml for 1 h, epithelial keratinization was observed after 4 and 5 days, respectively, whereas it occurred after 6 days in control cultures. A clear dose-response relationship was found in the promotion of epithelial keratinization by MNNG.This work was supported by a Grant-in-Aid for Cancer Research from the Ministry of Education, Science and Culture, Japan.Acknowledgment. The authors wish to express their gratitude to Prof. T. Mizuno of the University of Tokyo for valuable suggestions. 相似文献
8.
Hippocrates’ assertion that ‘what the lance does not heal, fire will’ underscores the fact that for thousands of years heat
has been used to treat a variety of diseases, including cancer. Indeed, spontaneous tumor remission has been observed in patients
following feverish infection [1], and expression of activated oncogenes, such as Ras, can render tumor cells sensitive to
heat compared with normal cells [2, 3]. In the past, a primary drawback to the use of heat as a clinical therapy was the inability
to selectively focus heat to tumors in situ. Of late, however, several approaches have been devised to deliver heat more precisely, including the use of heated nanoparticles,
making hyperthermia a more clinically tractable treatment option [4, 5]. Despite these practical advances, the mechanisms
responsible for heat shock-induced cell death remain controversial and ill-defined. In this Visions and Reflections we discuss recent findings surrounding the initiation of heat shock-induced apoptosis, and propose future areas of research.
Received 17 March 2007; received after revision 25 April 2007; accepted 22 May 2007 相似文献
9.
The intersection between art, poetry, philosophy and science was the leitmotif which guided the lives and careers of romantic natural philosophers including that of the Danish natural philosopher, H. C. Ørsted. A simple model of Ørsted’s career would be one in which it was framed by two periods of philosophical speculation: the youth’s curious and idealistic interest in new attractive thoughts and the experienced man’s mature reflections at the end of his life. We suggest that a closer look at the epistemological aspects of his works on the theory of beauty reveals a connection between this late work and his early philosophical work including experimental philosophy, but also with the work in teaching and textbook writing, that lies in between. The latter includes Ørsted’s view on the application of mathematics in natural philosophy as well as his failed attempt at a genetic presentation of elementary geometry. 相似文献
10.
Anjana Silva Ben Cristofori-Armstrong Lachlan D. Rash Wayne C. Hodgson Geoffrey K. Isbister 《Cellular and molecular life sciences : CMLS》2018,75(23):4465-4478
Snake venom α-neurotoxins potently inhibit rodent nicotinic acetylcholine receptors (nAChRs), but their activity on human receptors and their role in human paralysis from snakebite remain unclear. We demonstrate that two short-chain α-neurotoxins (SαNTx) functionally inhibit human muscle-type nAChR, but are markedly more reversible than against rat receptors. In contrast, two long-chain α-neurotoxins (LαNTx) show no species differences in potency or reversibility. Mutant studies identified two key residues accounting for this. Proteomic and clinical data suggest that paralysis in human snakebites is not associated with SαNTx, but with LαNTx, such as in cobras. Neuromuscular blockade produced by both subclasses of α-neurotoxins was reversed by antivenom in rat nerve–muscle preparations, supporting its effectiveness in human post-synaptic paralysis. 相似文献
11.
Pili in Gram-negative and Gram-positive bacteria — structure, assembly and their role in disease 总被引:2,自引:0,他引:2
Many bacterial species possess long filamentous structures known as pili or fimbriae extending from their surfaces. Despite
the diversity in pilus structure and biogenesis, pili in Gram-negative bacteria are typically formed by non-covalent homopolymerization
of major pilus subunit proteins (pilins), which generates the pilus shaft. Additional pilins may be added to the fiber and
often function as host cell adhesins. Some pili are also involved in biofilm formation, phage transduction, DNA uptake and
a special form of bacterial cell movement, known as ‘twitching motility’ In contrast, the more recently discovered pili in
Gram-positive bacteria are formed by covalent polymerization of pilin subunits in a process that requires a dedicated sortase
enzyme. Minor pilins are added to the fiber and play a major role in host cell colonization.
This review gives an overview of the structure, assembly and function of the best-characterized pili of both Gram-negative
and Gram-positive bacteria.
Received 08 August 2008; received after revision 24 September 2008; accepted 01 October 2008 相似文献
12.
Establishment of vertebrate left–right asymmetry is a critical process for normal embryonic development. After the discovery of genes expressed asymmetrically along the left–right axis in chick embryos in the mid 1990s, the molecular mechanisms responsible for left–right patterning in vertebrate embryos have been studied extensively. In this review article, we discuss the mechanisms by which the initial symmetry along the left–right axis is broken in the mouse embryo. We focus on the role of primary cilia and molecular mechanisms of ciliogenesis at the node when symmetry is broken and left–right asymmetry is established. The node is considered a signaling center for early mouse embryonic development, and the results we review here have led to a better understanding of how the node functions and establishes left–right asymmetry. 相似文献
13.
14.
In vertebrates, internal organs are positioned asymmetrically across the left-right (LR) axis, placing them in a defined area within the body. This LR asymmetric placement is a conserved feature of the vertebrate body plan. Events determining LR asymmetry occur during embryonic development, and are regulated by the coordinated action of genetic mechanisms that are evolutionarily conserved among vertebrates. Recent studies using zebrafish have provided new insights into how the Kupffer's vesicle organizer region is generated, and how it relays LR asymmetry information to the lateral plate mesoderm. In this review, we summarize recent advances in zebrafish and describe our current understanding of the mechanisms underlying these processes. 相似文献
15.
C. R. Pace-Asciak N. S. Edwards M. C. Carrara 《Cellular and molecular life sciences : CMLS》1980,36(6):635-637
Summary Tritium-labelled PGF2 was administered i.v. into rats of varying ages (2, 4, 6 weeks and adult). Urine was collected and assayed for radioactive products by thin-layer-chromatography. Results showed a distinctly different urinary profile between the 2-week-old and the adult rat. While the urinary pattern from the 2-week-old rat gave a single less polar product than PGF2, the pattern from the adult rat gave products more polar than PGF2. Urine from the 4- and 6-week-old rats gave a mixture of these types of products. These results indicate that some prostaglandin catabolic pathway (likely the -oxidative system) is activated in vivo within the 4–6-week postnatal period in the rat.Supported by a grant (MT-4181) to C.P.-A. from the Medical Research Council of Canada.This study is in partial fulfillment of the requirements for a Ph.D. degree in the Department of Pharmacology, University of Toronto. 相似文献
16.
During the nineteenth century French chemistry was marked by an outstanding number of Alsatian chemists whose scientific contributions cannot be ignored. Especially following the Franco-Prussian War, their regional origin was given a particular importance as a means of affirming their singularity on the French scientific scene. However, some questions may be raised: can we distinguish the Alsatians from other French chemists before 1870? Were they a homogeneous group sharing a common origin? The aim of this article therefore, is, to show that by their theoretical options within chemistry, their personal and professional relationships, as well as by their participation in various common initiatives, they organized themselves both formally and informally within the Parisian scientific community. Amongst these forms of organization the research school of Charles Adolphe Wurtz (1817-84) emerges as the nucleus of what we may envisage as a network of Alsatian chemists working in Paris, in the second half of the nineteenth century. 相似文献
17.
Seyma Bahdoudi Ikram Ghouili Mansour Hmiden Jean-Luc do Rego Benjamin Lefranc Jérôme Leprince Julien Chuquet Jean-Claude do Rego Ann-Britt Marcher Susanne Mandrup Hubert Vaudry Marie-Christine Tonon Mohamed Amri Olfa Masmoudi-Kouki David Vaudry 《Cellular and molecular life sciences : CMLS》2018,75(11):2075-2091
Parkinson’s disease (PD) is a neurodegenerative disorder characterized by a progressive loss of dopamine (DA) neurons through apoptotic, inflammatory and oxidative stress mechanisms. The octadecaneuropeptide (ODN) is a diazepam-binding inhibitor (DBI)-derived peptide, expressed by astrocytes, which protects neurons against oxidative cell damages and apoptosis in an in vitro model of PD. The present study reveals that a single intracerebroventricular injection of 10 ng ODN 1 h after the last administration of 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) prevented the degeneration of DA neurons induced by the toxin in the substantia nigra pars compacta of mice, 7 days after treatment. ODN-mediated neuroprotection was associated with a reduction of the number of glial fibrillary acidic protein-positive reactive astrocytes and a strong inhibition of the expression of pro-inflammatory genes such as interleukins 1β and 6, and tumor necrosis factor-α. Moreover, ODN blocked the inhibition of the anti-apoptotic gene Bcl-2, and the stimulation of the pro-apoptotic genes Bax and caspase-3, induced by MPTP in the substantia nigra pars compacta. ODN also decreased or even in some cases abolished MPTP-induced oxidative damages, overproduction of reactive oxygen species and accumulation of lipid oxidation products in DA neurons. Furthermore, DBI knockout mice appeared to be more vulnerable than wild-type animals to MPTP neurotoxicity. Taken together, these results show that the gliopeptide ODN exerts a potent neuroprotective effect against MPTP-induced degeneration of nigrostriatal DA neurons in mice, through mechanisms involving downregulation of neuroinflammatory, oxidative and apoptotic processes. ODN may, thus, reduce neuronal damages in PD and other cerebral injuries involving oxidative neurodegeneration. 相似文献
18.
T. P. Leist A. Meager T. Exley R. M. Zinkernagel 《Cellular and molecular life sciences : CMLS》1991,47(6):630-632
Summary The role of interferon (IFN) in controlling chronic infections ofListeria monocytogenes (Listeria) was studied in athymic C57BL/6nu/nu mice, and by treating thymectomized C57BL/6 +/+ mice with monoclonal rat CD4 and CD8-specific monoclonal antibodies (Mab). Mice treated with a combination of the two T cell subset antibodies were similar to athymic, nude mice in being able to contol Listeria infection, keeping the titers below 3–5 log10 bacteria per organ, but they could not eliminate them completely. Treatment with antibodies to IFN of nude or CD4+ + CD8+-T cell-depleted mice suffering from chronic Listeria infection caused a marked increase of Listeria titers, in liver and spleen. This result implies a role of IFN in maintaining anti-Listeria resistance in mice lacking mature T cells. 相似文献
19.
J. Hubertha Bijtel 《Cellular and molecular life sciences : CMLS》1960,16(2):74-75
Zusammenfassung Vom ektodermalen Proctodaeum wächst ein kleiner Divertikel dem Vornierengang entgegen und vereinigt sich mit dessen kaudalem Ende. Einen weiteren Anteil hat das Proctodaeum an der Bildung des Vornierenganges nicht. Zugleich mit dem Proctodaeum invaginiert Material für den Mesonephros, das sich in Zellgruppen entlang dem hinteren Ende des Vornierenganges lagert. 相似文献
20.
Summary Liver membrane adenylate cyclase activity was significantly higher and 5-nucleotidase activity significantly lower in alloxan diabetic rats compared with normal rats. 相似文献