Effects of clomiphene citrate and progesterone on resting and proliferative cell-populations in resting and proliferative cell-populations in mouse uterine epithelium.
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Resting cells (GO cells) of the uterine surface epithelium in castrated mice began to synthesize DNA with high synchrony from 10 hr after the injection of 50 ng of estradiol-17beta with or without 5.5 mug of clomiphene citrate. Highly synchronized DNA synthesis in GO cells elicited with estradiol was delayed approximately 5 hr when the simultaneous administration of 0.5 mg of progesterone was given. In GO cells of castrated mice which received 5.5 mug of clomiphene or 55 mug of clomiphene plus 50 ng of estradiol, DNA synthesis with partial synchrony began 15 hr after the injection. The effects of estradiol were completely suppressed by the administration of 55 mug of clomiphene. It is suggested that the inhibitory action of clomiphene may be due to the competitive blocking of estrogen binding, while progesterone suppresses the estrogen-induced DNA synthesis of the surface epithelium and transfers them to the GO cell-compartment. (+info)
Characterization, cDNA cloning, and functional expression of mouse ileal sodium-dependent bile acid transporter.
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Mouse ileal sodium dependent bile acid transporter (ISBT) was characterized using isolated enterocytes. Only enterocytes from the most distal portion showed Na+-dependent [3H]taurocholate uptake. Northern blot analysis using a probe against mouse ISBT revealed the expression of mouse ISBT mRNA to be restricted to the distal ileum. The Km and Vmax for Na+-dependent [3H]taurocholate transport into isolated ileocytes were calculated as 27 microM and 360 pmol/mg protein/min, respectively. Uptake of [3H]taurocholate was inhibited by N-ethylmaleimide. We have cloned ISBT cDNA from mouse ileum. The cDNA included the entire open reading frame coding 348 amino acid protein with seven hydrophobic segments and two N-glycosylation sites. COS-7 cells transfected with the expression vector containing this cDNA expressed Na+-dependent [3H]taurocholate uptake activity with a Km of 34 microM. (+info)
Expression of folate receptor alpha in the mammalian retinol pigmented epithelium and retina.
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PURPOSE: Folic acid is essential for DNA, RNA, and protein synthesis, and deficiencies in folate can lead to nutritional amblyopia and optic neuropathy. The transport of folate from the choroidal blood supply to the retina is only now beginning to be understood. The reduced-folate transporter was reported recently to be present in cultured human retinal pigment epithelial (RPE) cells and is thought to be localized to the apical region of these cells. The authors hypothesize that the RPE plays a role in the vectorial transport of folate from the choroidal blood to the neural retina and uses not only the reduced-folate transporter but also the folate receptor alpha in mediating this transport. The purpose of the present study was to determine whether the folate receptor alpha was present in the RPE and, if so, whether it was distributed along the basolateral membrane of the RPE, supporting a role for the protein in the initial steps of folate transport into the RPE. METHODS: The expression of the folate receptor alpha in mouse RPE was analyzed by reverse transcription-polymerase chain reaction (RT-PCR), functional assays, in situ hybridization, immunohistochemistry, and laser scanning confocal microscopy. RESULTS: RT-PCR analysis, cloning of the RT-PCR product, and subsequent sequencing established that folate receptor alpha mRNA transcripts are expressed in the mouse RPE/choroid and are expressed also in the neural retina. A heterologous functional expression assay using MTX(R)-ZR-75-1 cells showed that the folate receptor alpha cDNA obtained by RT-PCR from the RPE/choroid complex and the neural retina was functional as assessed by the binding of folic acid and by the uptake of N5-methyltetrahydrofolate. In situ hybridization localized the folate receptor alpha mRNA to the mouse RPE cells and to cells of the neural retina. The folate receptor alpha was detected immunohistochemically in the mouse and rat RPE and in several layers of the neural retina. Laser scanning confocal microscopy revealed the distribution of the folate receptor alpha along the basolateral region of the RPE and not the apical region. CONCLUSIONS: The present work represents the first analysis of the folate receptor alpha expression in intact mammalian retina. The receptor is present and functional in mouse RPE. It is distributed specifically along the basolateral surface of the RPE and is proposed to work in a coordinated manner with the reduced-folate transporter in the vectorial transport of folate from the choroidal blood to the neural retina. (+info)
Retardation of bone growth in triamcinolone-treated mice.
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Immature mice were treated for up to 8 weeks with daily doses of triamcinolone diacetate. The epiphyseal cartilage plate and its surrounding bone from the humeral head were studied histologically at regular intervals. Concomitantly, roentgenographic measurements were performed on the humeri in toto. By the tenth injection significant morphological changes were noted in the cartilaginous plate, followed by complete cessation of bone growth. Severe triglyceride accumulation appeared in the experimental livers and humeral bone marrow. Osteoporosis also occurred and became severe from the fifth week of triamcinolone administration. Possible explanations for the above findings are discussed. (+info)
Age-dependent resistance to Cryptosporidium muris (strain MCR) infection in golden hamsters and mice.
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An age-dependent aspect of resistance to Cryptosporidium muris (strain MCR) infection was monitored in Syrian golden hamsters, Mesocricetus auratus, at 1-, 5- and 10-week of age and in ICR mice. Mus musculus, at 3-, 12-, and 15-week of age orally inoculated with a single dose of 2 x 10(6) oocysts, respectively. The prepatent periods for both animals were similar, independent of age, but the patency was significantly longer in younger hamsters (P < 0.001) and a long tendency in younger mice. Hamsters infected at 1-week of age excreted about 10 times higher oocysts than those at 5- and 10-week of age. However, the total oocyst output was similar among mice of different ages. There was a good correlation between the length of the patency and the total oocyst output in hamsters (R = 0.9646), but not in mice (R = 0.4561). The immunogenicity of the parasite to homologous challenge infections was very strong in hamsters and relatively strong in mice. These results indicate that acquired resistance to C. muris infection is age-related and the innate resistance is independent of age of hamsters, and that both innate and acquired resistance, on the contrary, are irrespective of age of mice. (+info)
Thalamocortical axons are influenced by chemorepellent and chemoattractant activities localized to decision points along their path.
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Thalamocortical axons (TCAs), which originate in dorsal thalamus, project ventrally in diencephalon and then dorsolaterally in ventral telencephalon to their target, the neocortex. To elucidate potentially key decision points in TCA pathfinding and hence the possible localization of guidance cues, we used DiI-tracing to describe the initial trajectory of TCAs in mice. DiI-labeled TCAs extend ventrally on the lateral surface of ventral thalamus. Rather than continuing this trajectory onto the lateral surface of the hypothalamus, TCAs make a sharp lateral turn into ventral telencephalon. This behavior suggests that the hypothalamus is repulsive and the ventral telencephalon attractive for TCAs. In support of this hypothesis, we find that axon outgrowth from explants of dorsal thalamus is biased away from hypothalamus and toward ventral telencephalon when cocultured at a distance in collagen gels. The in vivo DiI analysis also reveals a broad cluster of retrogradely labeled neurons in the medial part of ventral telencephalon positioned within or adjacent to the thalamocortical pathway prior to or at the time TCAs are extending through it. The axons of these neurons extend into or through dorsal thalamus and appear to be coincident with the oppositely extending TCAs. These findings suggest that multiple cues guide TCAs along their pathway from dorsal thalamus to neocortex: TCAs may fasciculate on the axons of ventral telencephalic neurons as they extend through ventral thalamus and the medial part of ventral telencephalon, and chemorepellent and chemoattractant activities expressed by hypothalamus and ventral telencephalon, respectively, may cooperate to promote the turning of TCAs away from hypothalamus and into ventral telencephalon. (+info)
Synchronized paroxysmal activity in the developing thalamocortical network mediated by corticothalamic projections and "silent" synapses.
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In mouse thalamocortical slices in vitro, the potassium channel blocker 4-AP and GABAA receptor antagonist bicuculline together induced spontaneous prolonged depolarizations in layer VI neurons from postnatal day 2 (P2), in ventroposterior nucleus neurons (VP) from P7, and in reticular nucleus neurons (RTN) from P8. Dual whole-cell recordings revealed that prolonged bursts were synchronized in layer VI, VP, and RTN. Bursts were present in cortex isolated from thalamus, but not in thalamus isolated from cortex, indicating that bursts originated in cortex and propagated to thalamus. Prolonged bursts were synchronized in layer VI when vertical cuts extended from pia mater through layers IV or V, but were no longer synchronized when cuts extended through layer VI and white matter. In voltage-clamp recordings before P10, burst conductance of all three neuronal populations was dominated by the NMDA receptor-mediated conductance, and therefore synapses were "silent". In cortex and RTN, after P10, bursts were associated with strong AMPA/kainate receptor-mediated conductances, and synapses had become "functional"; silent synapses persisted in a large proportion of VP cells after P10. Before P9, the NMDA receptor antagonist APV or the non-NMDA receptor antagonist CNQX blocked the prolonged bursts. After P9, CNQX continued to block the prolonged bursts, but APV merely shortened their duration. Thus, NMDA receptor-based silent synapses are essential for paroxysmal corticothalamic activity during early postnatal development, and connections between layer VI neurons are sufficient for horizontal cortical synchronization. (+info)
Gas supersaturation in the cecal wall of mice due to bacterial CO2 production.
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PCO2 in the lumen and serosa of cecum and jejunum was measured in mice. The anesthetic used was a fentanyl-fluanisone-midazolam mixture. PCO2 was recorded in vivo and postmortem. PCO2 was 409 +/- 32 Torr (55 +/- 4 kPa) in the cecal lumen and 199 +/- 22 Torr (27 +/- 3 kPa) on the serosa in normal mice. Irrigation of the cecum resulted in serosal and luminal PCO2 levels of 65-75 Torr. Cecal PCO2 was significantly lower in germ-free mice (65 +/- 5 Torr). Cecal PCO2 increased significantly after introduction of normal bacterial flora into germ-free mice. Introduction of bacterial monocultures into germ-free mice had no effect. After the deaths of the mice, cecal PCO2 increased rapidly in normal mice. The intestinal bacteria produced the majority of the cecal PCO2, and the use of tonometry in intestinal segments with a high bacterial activity should be interpreted with caution. We propose that serosal PCO2 levels >150-190 Torr (20-25 kPa) in the cecum of mice with a normal circulation may represent a state of gas supersaturation in the cecal wall. (+info)