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Rapid augmentation of prolactin cell number and secretory capacity by an estrogen-induced factor released from the neurointermediate lobe 总被引:1,自引:0,他引:1
17 beta-Estradiol (E2) has been shown to exert an acute stimulatory effect on PRL secretion via an indirect action involving the neurointermediate lobe (NIL). In the present study we used a reverse hemolytic plaque assay to determine whether this effect was manifested as an augmentation of the number of PRL secretors and/or an increase in the amount of hormone released per PRL cell. Cultures of anterior pituitary (AP) and NIL cells from ovariectomized rats were cultured overnight, exposed to the treatment (E2 or vehicle) for 3 h, and then subjected to a reverse hemolytic plaque assay that was carried out in the presence or absence of TRH. Concurrent exposure of AP cells to E2 and NIL cells evoked an 11-12% increase in the overall proportion of PRL-secreting cells. This was true when the AP and NIL cells were incubated as a mixed culture and when the two cell types were maintained in the same petri dish but on separate plastic supports, and TRH did not significantly influence this response. The effect of E2 on the number of PRL secretors was negated when NIL cells were not present throughout the experiment or when they were removed from the cultures just before commencement of E2 treatment. Simultaneous treatment with E2 and NIL cells also significantly augmented the sizes of PRL plaques produced under basal conditions by AP cells. Taken together, these results demonstrate that E2 stimulates NIL cells to release an activity that enhances PRL secretion in two ways: 1) by recruiting additional PRL cells into the secretory pool, and 2) by augmenting the secretory capacity of individual PRL cells. 相似文献
4.
GP SCHWAB AL BLUM E BODNER B DALLEMAGNE K GLASER H KOOP F PACE W RÖSCH JR SIEWERT G WETSCHER 《Journal of gastroenterology and hepatology》1997,12(12):785-789
Gastroesophageal reflux disease (GERD) is the most common disease of the upper gastrointestinal tract. With the introduction of proton pump inhibitors medical treatment of GERD has been significantly improved. However, the development of laparoscopic antireflux surgery resulted in an increasing interest of surgeons in this disease. An interactive meeting was organized in order to develop an agreement between gastoenterologists and surgeons regarding therapeutic decisions and this is the main topic of this paper. 相似文献
5.
The sudden appearance of prolactin-releasing cells during the early postnatal period of the rat is initiated by a small milk-borne
peptide. Depriving newborn rats of this early milk factor severely retards mammotrope differentiation during the neonatal
period. In the present work, we extend our study of early milk deprivation to the adult. To this end, newborn litters were
crossfostered onto mothers that had given birth the same day or one week earlier in order to deprive pups in the latter group
of early milk. At 5, 15, and 30 d of age, rats deprived of such milk had decreased percentages of mammotropes (as measured
by reverse hemolytic plaque assay, RHPA) when compared to nondeprived animals (P<0.05). By 45 d, the percentage of mammotropes was similar for the two crossfostered groups (P>0.1) and this persisted through d 60. Subsequently, we assessed the secretory capacity of mammotropes from 60-d old rats
to secretagogues and found that early milk deprivation had no effect on basal prolactin release (P>0.1), but that it augmented
hormone secretion evoked by thyrotropin-releasing hormone (TRH, 100 nM; P<0.01). The inhibitory response to dopamine (DA; 1 μM) and the stimulatory response to angiotensin II (AGII; 100 nM) were not altered by early milk deprivation (P>0.1). Taken together, these results demonstrate that factors in milk from early lactation are required for normal mammotrope
differentiation, and that the delay induced by early milk deprivation leads to altered secretory function of mammotropes in
adult animals. 相似文献
6.
Low-artifact intravascular devices: MR imaging evaluation 总被引:2,自引:0,他引:2
Teitelbaum GP; Ortega HV; Vinitski S; Stern H; Tsuruda JS; Mitchell DG; Rifkin MD; Bradley WG Jr 《Radiology》1988,168(3):713-719
Flow-phantom magnetic resonance (MR) imaging, with use of both spin-echo (SE) and gradient-echo (GRE) techniques at 1.5 T, was performed on the percutaneous Greenfield (beta-III titanium alloy [TMA wire]), Amplatz (MP32-N alloy), and Simon nitinol filters and TMA wire facsimiles of the bird's nest, Gunther, new retrievable, and Amplatz vena caval filters. SE imaging allowed detection of thrombi as small as 5 X 5 mm trapped within the percutaneous Greenfield, Simon nitinol, and TMA-wire facsimile filters; with the MP32-N Amplatz filter, a larger volume of thrombus (10 X 20-mm clots) was necessary for clot detection. GRE imaging allowed detection of intraluminal tilting of the percutaneous Greenfield and facsimile Amplatz (TMA-wire) filters. GRE imaging was useful for demonstrating postfilter turbulence due to clots, which was greatest for the Amplatz filter. Imaging of facsimile vascular devices made of tantalum or TMA wire did not cause the severe "black-hole" MR artifacts typical of the stainless-steel devices. SE and GRE imaging were very useful for determining caval patency in two patients with previously placed Mobin-Uddin filters. Noninvasive MR evaluation of blood vessels in the presence of a variety of low-artifact intravascular devices appears feasible. 相似文献
7.
8.
Sequence comparison of human and yeast telomeres identifies structurally distinct subtelomeric domains 总被引:6,自引:2,他引:6
Flint J; Bates GP; Clark K; Dorman A; Willingham D; Roe BA; Micklem G; Higgs DR; Louis EJ 《Human molecular genetics》1997,6(8):1305-1313
We have sequenced and compared DNA from the ends of three human
chromosomes: 4p, 16p and 22q. In all cases the pro-terminal regions are
subdivided by degenerate (TTAGGG)n repeats into distal and proximal sub-
domains with entirely different patterns of homology to other chromosome
ends. The distal regions contain numerous, short (<2 kb) segments of
interrupted homology to many other human telomeric regions. The proximal
regions show much longer (approximately 10-40 kb) uninterrupted homology to
a few chromosome ends. A comparison of all yeast subtelomeric regions
indicates that they too are subdivided by degenerate TTAGGG repeats into
distal and proximal sub-domains with similarly different patterns of
identity to other non-homologous chromosome ends. Sequence comparisons
indicate that the distal and proximal sub-domains do not interact with each
other and that they interact quite differently with the corresponding
regions on other, non- homologous, chromosomes. These findings suggest that
the degenerate TTAGGG repeats identify a previously unrecognized,
evolutionarily conserved boundary between remarkably different subtelomeric
domains.
相似文献
9.
Frawley KA Durham K Stafford M Booth P 《Journal of AHIMA / American Health Information Management Association》1993,64(10):suppl 4 p. following p. 16
10.