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1.
Summary Following fasting and refeeding, the colonic epithelium of the rat exhibits a marked hyperplasia. This response is of a similar magnitude but of a longer duration to that observed in mice. This response is not affected by reducing serum calcium levels to those reported to alter normal tissue proliferation in vivo.Supported in part by HRSF, grant T-90, and by grants No. 1-PO2-CA10438 and No. 5-TO10-CA05224 from the National Cancer Institute, DHEW.The authors wish to thank Andrew M. Ruland for performing the serum calcium assays and George Miller of Zivic-Miller Laboratories.  相似文献   

2.
Evidence for a modulation of the stress response by the pineal gland   总被引:2,自引:0,他引:2  
R Khan  S Daya  B Potgieter 《Experientia》1990,46(8):860-862
Wistar rats show a circadian variation in their response to stress. Pinealectomy exacerbates stress-induced gastric ulceration in rats. This effect is counteracted by melatonin administration.  相似文献   

3.
Summary Wistar rats show a circadian variation in their response to stress. Pinealectomy exacerbates stress-induced gastric ulceration in rats. This effect is counteracted by melatonin administration.  相似文献   

4.
This paper reconsiders the challenge presented to scientific realism by the semantic incommensurability thesis. A twofold distinction is drawn between methodological and semantic incommensurability, and between semantic incommensurability due to variation of sense and due to discontinuity of reference. Only the latter presents a challenge to scientific realism. The realist may dispose of this challenge on the basis of a modified causal theory of reference, as argued in the author’s 1994 book, The incommensurability thesis. This referential response has been the subject of a charge of meta-incommensurability by Hoyningen-Huene et al. (1996), who argue that the realist’s referential response begs the question against anti-realist advocates of incommensurability. In reply, it is noted that a tu quoque rejoinder is available to the realist. It is also argued that the dialectical situation favours the scientific realist, since the anti-realist defence of incommensurability depends on an incoherent distinction between phenomenal world and world-in-itself. In light of such incoherence, and a strong commonsense presumption in favour of realism, the referential response to semantic incommensurability may be justifiably based on realism.  相似文献   

5.
The investigation of tooth eruption in dermoid cysts of the ovary allows one to observe in the chorion at the level of the epithelial attachment, an anatomical component that seems to correspond to a local system of defense. Up until now this has been considered to be a secondary inflammatory response resulting from the bacterial or mechanical assault. This component is found to form when the tooth erupts and constitutes an important element in the physico-pathogical process and of the immune response of the dental organ.  相似文献   

6.
Summary Removal of the submaxillary gland (SMG) from male but not female mice caused a suppressed immune response to sheep red blood cells. Administration of a SMG saline extract from male mice to SMG-ectomized males restored the suppressed response to control levels. This suggests that the male mouse SMG contains a factor(s), possibly of an endocrine nature, capable of influencing cells involved in an immune response.  相似文献   

7.
Summary The release of insulin which occurred in response to arginine, in the conscious calf, differed from that which occurs in response to glucose in that it was not significantly affected by either adrenergic or muscarinic blocking agents. Release of pancreatic glucagon was reduced by pretreatment with phentolamine.This work was supported by the British Diabetic Association. It is a particular pleasure to acknowledge the skilled assistance provided by Messrs P. M. M. Bircham and G. P. McGregor.  相似文献   

8.
Summary The ratio at which adrenaline and noradrenaline are released from the adrenal medulla in response to stimulation of the splanchnic nerve has been established in the conscious calf. The proportion of adrenaline: noradrenaline was closely similar to that in which the 2 amines are stored in the gland and released in response to other stimuli in conscious, but not anaesthetized, calves.Acknowledgments. This work has been supported by a grant from the Agricultural Research Council, and we are also indebted to Dr D.M. Burley (Ciba) for his continued support. It is a pleasure to acknowledge the skilled technical assistance provided by Mr P.M.M. Bircham.  相似文献   

9.
The aim of this article is to provide a historical response to Michel Janssen’s (2009) claim that the special theory of relativity establishes that relativistic phenomena are purely kinematical in nature, and that the relativistic study of such phenomena is completely independent of dynamical considerations regarding the systems displaying such behavior. This response will be formulated through a historical discussion of one of Janssen's cases, the experiments carried out by Walter Kaufmann on the velocity-dependence of the electron's mass. Through a discussion of the different responses formulated by early adherents of the principle of relativity (Albert Einstein, Max Planck, Hermann Minkowski and Max von Laue) to these experiments, it will be argued that the historical development of the special theory of relativity argues against Janssen's historical presentation of the case, and that this raises questions about his general philosophical claim. It will be shown, more specifically, that Planck and Einstein developed a relativistic response to the Kaufmann experiments on the basis of their study of the dynamics of radiation phenomena, and that this response differed significantly from the response formulated by Minkowski and Laue. In this way, it will be argued that there were, at the time, two different approaches to the theory of relativity, which differed with respect to its relation to theory, experiment, and history: Einstein's and Planck's heuristic approach, and Minkowski's and Laue's normative approach. This indicates that it is difficult to say, historically speaking, that the special theory of relativity establishes the kinematical nature of particular phenomena. Instead, it will be argued that the theory of relativity should not be seen as a theory but rather as outlining an approach, and that the nature of particular scientific phenomena is something that is open to scientific debate and dispute.  相似文献   

10.
Summary Approximately 100 times more illumination is required to produce pigment dispersion in the melanophores of eyestalkless fiddler crabs (Uca pugilator) than in the melanophores of intact crabs. The pigment in melanophores of isolated legs will normally disperse in response to irradiation, but this response is inhibited by cytochalasin B.This investigation was supported by a Faculty Research Grant from Western Kentucky University toT. P. Coohill and by Grant No. GB-27497 toM. Fingerman from the National Science Foundation.  相似文献   

11.
Myocardial infarction (MI) is caused by the occlusion of a coronary artery due to underlying atherosclerosis complicated by localized thrombosis. The blockage of blood flow leads to cardiomyocyte (CM) death in the infarcted area. Adult mammalian cardiomyocytes have little capacity to proliferate in response to injury; however, some pathways active during embryogenesis and silent during adult life are recruited in response to tissue injury. One such example is hedgehog (Hh) signaling. Hh is involved in the embryonic development of the heart and coronary vascular system. Pathological conditions including ischemia activate Hh signaling in adult tissues. This review highlights the involvement of Hh signaling in ischemic tissue regeneration with a particular emphasis on heart regeneration and discusses its potential role as a therapeutic agent.  相似文献   

12.
B V Siegel  J I Morton 《Experientia》1977,33(3):393-395
The inclusion of vitamin C in the drinking water of BALB/c mice was without effect on the humoral antibody response to sheep red blood cells and bacterial lipopolysaccharide. However, there was a significantly increased cell-mediated immune response as determined by increased T-lymphocyte responses to concanavalin A. This might suggest a mechanism, along with interferon enhancement, for the possible protection by vitamin C against some viral infections.  相似文献   

13.
This paper proposes an approach that models and forecasts sales through a flexible parametric response function (multifunctional), allowing for differentiated behavioural assumptions of the response determinants to be specified, and uses neural network modelling as a re‐specification tool for the response model in order to improve forecasting performance. An initial experiment on a sample of sales data demonstrates feasibility and gives comparative insights via alternative model specifications. Copyright © 2005 John Wiley & Sons, Ltd.  相似文献   

14.
The skin is our primary shield against microbial pathogens and has evolved innate and adaptive strategies to enhance immunity in response to injury or microbial insult. The study of antimicrobial peptide (AMP) production in mammalian skin has revealed several of the elegant strategies that AMPs use to prevent infection. AMPs are inducible by both infection and injury and protect the host by directly killing pathogens and/or acting as multifunctional effector molecules that trigger cellular responses to aid in the anti-infective and repair response. Depending on the specific AMP, these molecules can influence cytokine production, cell migration, cell proliferation, differentiation, angiogenesis and wound healing. Abnormal production of AMPs has been associated with the pathogenesis of several cutaneous diseases and plays a role in determining a patient’s susceptibility to pathogens. This review will discuss current research on the regulation and function of AMPs in the skin and in skin disorders.  相似文献   

15.
Acetylcholine releases calcium from cytoplasmic stores and permits an influx of calcium in salivary acinar cells. The resultant rise in [Ca2+]i causes an increase in potassium permeability which is an important part of the secretory response. We have investigated the effects of 12-0-tetradecanoyl phorbol-13-acetate, a potent activator of protein kinase C, upon this regulation of potassium permeability in superfused pieces of rat submandibular salivary gland. This compound inhibited the initial [Ca2+]o-independent component of the response of acetylcholine but had no effect upon the subsequent [Ca2+]o-dependent phase. This compound does not, therefore, appear to inhibit receptor-regulated calcium influx.  相似文献   

16.
Vitamin C and the immune response   总被引:1,自引:0,他引:1  
Summary The inclusion of vitamin C in the drinking water of BALB/c mice was without effect on the humoral antibody response to sheep red blood cells and bacterial lipopolysaccharide. However, there was a significantly increased cell-mediated immune response as determined by increased T-lymphocyte responses to concanavalin A. This might suggest a mechanism, along with interferon enhancement, for the possible protection by vitamin C against some viral infections.We thank Miss Wendy Treat for excellent technical assistance.  相似文献   

17.
P S Campbell 《Experientia》1983,39(1):108-109
Rats treated neonatally with testosterone propionate exhibit a reduced uterine growth response to estradiol administration prepubertally. This androgen-induced impairment is the consequence of developmental effects on both the ovary and the hypothalamic-pituitary complex, although the latter is the more sensitive.  相似文献   

18.
Cats were trained to press a key during a variable interval schedule of reinforcement with a limited hold contingency. The main modifications of the response rate were observed when the subject missed one reinforcement or obtained more than one reinforcement during the limited hold. The existence of a zone of lesser variability in the mean response rate is shown to be linked to the occurrence of the last reinforcement. This result suggests an original methodological contingency concerning the use of conditioned suppression in psychophysics. The schedule of sensory stimulation should be established for each subject during that period of lesser variability between two reinforcements.  相似文献   

19.
Predicting the direction of central banks' target interest rates is important for various market participants. This paper advances procedures for predicting the direction of the federal funds target rate using a dynamic extension of the multinomial logit model. I find that the 6‐month Treasury bill spread relative to the federal funds rate, the unemployment rate and the real GDP growth rate have superior predictive content for the direction of the target a week to several months ahead. When these variables are employed, lagged target changes do not provide additional predictive power. This suggests that the apparent positive serial dependence of the target changes is due to the Fed's systematic response to autocorrelated macroeconomic variables. Copyright © 2010 John Wiley & Sons, Ltd.  相似文献   

20.
Summary The surround response mechanism in on-center X-cells in cat retina was found to be bimodally distributed and weak or nonexistent in the receptive field middle. An on-inhibition measure was used to assess surround mechanism gain.Acknowledgments. This research is supported by Public Health Service grant No. EY 00701.  相似文献   

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