We report the identification and expression pattern of a full-length human cDNA and a partial mouse cDNA encoding cyclin B3. Cyclin B3 (CCNB3) is conserved from Caenorhabditis elegans to Homo sapiens and has an undefined meiotic function in female, but not male Drosophila melanogaster. We show that H. sapiens cyclin B3 interacts with cdk2, is localized to the nucleus, and is degraded during anaphase entry after the degradation of cyclin B1. Degradation is dependent on sequences conserved in a destruction box motif. Overexpression of nondegradable cyclin B3 blocks the mitotic cell cycle in late anaphase, and at higher doses it can interfere with progression through G 1 and entry into S phase. H. sapiens cyclin B3 mRNA and protein are detected readily in developing germ cells in the human testis and not in any other tissue. The mouse cDNA has allowed us to further localize cyclin B3 mRNA to leptotene and zygotene spermatocytes. The expression pattern of mammalian cyclin B3 suggests that it may be important for events occurring in early meiotic prophase I.Cyclins are positive regulatory subunits of the cyclin-dependent kinases (cdks).1 Cyclins increase kinase activity by inducing structural changes in the cdk (1). Cyclins also provide substrate binding motifs (2, 3), signals that localize cdks (4, 5), and motifs that allow the incorporation of the cdk into higher order molecular complexes (6, 7). Although first identified as regulators of mitotic cell cycle transitions, cyclin-cdk complexes have other roles: cyclin C-cdk8 and cyclin H-cdk7 regulate transcription as part of the polymerase II holoenzyme (8 -10), pho80-pho85 regulates the localization of the pho4 transcription factor (11), p35-cdk5 regulates neuronal function (12, 13), and cyclin A1, with an unidentified cdk, regulates the pachytene to diplotene transition during male gametogenesis (14).Originally cloned from a chicken cDNA library, cyclin B3 is expressed at very low levels in virally transformed hematopoietic cell lines and early embryonic stages of chicken. When Gallus gallus cyclin B3 is expressed in HeLa cells, it is nuclear, interacts with cdk2 and cdc2, and is associated with a modest histone H1 kinase activity (15). In Drosophila, cyclin B3 is expressed in both mitotic and meiotic cells. In mitotic cells, it is only required when either cyclin A or cyclin B1 is absent. Its abundance is down-regulated during the metaphase to anaphase transition, following degradation of cyclin B1 (16). Overexpression of a nondegradable cyclin B3 is associated with chromatin decondensation defects at the end of mitosis (17). Cyclin B3 is essential for fertility; but unlike cyclin B1 deficiency, infertility of cyclin B3-deficient flies is restricted to the female germ line and does not appear to involve defects in ovary structure or in meiosis I entry (16).We report the cloning of a full-length human cyclin B3 cDNA and a partial mouse cyclin B3 cDNA. Like the previously described chicken and Drosophila homologs, when mammalian cyclin B3 expression is enforced in m...

Abstract-Central command is a feedforward neural mechanism that evokes parallel modifications of motor and cardiovascular function during arousal and exercise. The neural circuitry involved has not been elucidated. We have identified a cholinergic neural circuit that, when activated, mimics effects on tonic and reflex control of circulation similar to those evoked at the onset of and during exercise. Central muscarinic cholinergic receptor (mAChR) activation increased splanchnic sympathetic nerve activity (SNA) as well as the range and gain of the sympathetic baroreflex via activation of mAChR in the rostral ventrolateral medulla (RVLM) in anesthetized artificially ventilated SpragueDawley rats. RVLM mAChR activation also attenuated and inhibited the peripheral chemoreflex and somatosympathetic reflex, respectively. Cholinergic terminals made close appositions with a subpopulation of sympathoexcitatory RVLM neurons containing either preproenkephalin mRNA or tyrosine hydroxylase immunoreactivity. M2 and M3 receptor mRNA was present postsynaptically in only non-tyrosine hydroxylase neurons. Cholinergic inputs to the RVLM arise only from the pedunculopontine tegmental nucleus. Chemical activation of this region produced increases in muscle activity, SNA, and blood pressure and enhanced the SNA baroreflex; the latter effect was attenuated by mAChR blockade. These findings indicate a novel role for cholinergic input from the pedunculopontine tegmental nucleus to the RVLM in central cardiovascular command. This pathway is likely to be important during exercise where a centrally evoked facilitation of baroreflex control of the circulation is required to maintain blood flow to active muscle. (Circ Res. 2007;100:284-291.)Key Words: baroreflex Ⅲ exercise Ⅲ chemoreflex Ⅲ somatosympathetic A distinct pattern of tonic and reflex cardiovascular adjustments is mediated by central command to ensure appropriate muscle and organ perfusion during different arousal or behavioral states, such as sleep and exercise. [1][2][3] Limited evidence implicates some regions within the pons and hypothalamus that could provide descending input to cardiovascular control sites 4 -6 ; however, the neural circuitry and neurotransmitters involved are yet to be elucidated.Activation of the central cholinergic system has a profound effect on cardiovascular and other autonomic functions. [7][8][9][10][11][12][13][14][15][16][17][18] Systemic or central administration of acetylcholinesterase inhibitors or muscarinic agonists increases blood pressure, 7-11 lowers body temperature, 12 and alters respiration. 13,14 Pressor responses can be evoked via activation of muscarinic receptors (mAChR) within several cardiovascular nuclei, including the posterior hypothalamus, 7 nucleus of the solitary tract, 15 and rostral ventrolateral medulla (RVLM). 10,11 Effects of central mAChR activation on cardiovascular reflexes are less well understood. 8,16,17 Sympathoexcitatory and hypertensive effects of intravenously administered physostigmine are largely mediated by ...

Despite the use of the sirolimus (rapamycin) drug-eluting coronary stent, diabetics are at increased risk of developing in-stent restenosis for unclear reasons. Hyperleptinemia, which often coexists with diabetes and metabolic syndrome, is an independent risk factor for progression of coronary artery disease. It has not been determined whether elevated circulating leptin decreases the efficacy of the sirolimus drug-eluting stent in inhibiting neointimal hyperplasia, the process underlying restenosis after stenting. Here we show that leptin activates the mammalian target of rapamycin (mTOR) signaling pathway in primary murine vascular smooth muscle cells (VSMC) and stimulates VSMC proliferation in a PI3K-dependent fashion. Exogenous leptin, administered at levels comparable to those found in obese humans, promotes neointimal VSMC hyperplasia in a murine femoral artery wire injury model. Leptin significantly increases the dose of the mTOR inhibitor sirolimus that is required for effective inhibition of neointimal formation. Combination therapy with LY294002, a PI3K inhibitor, and sirolimus effectively inhibits leptin-enhanced neointimal hyperplasia. These data show that, in the setting of hyperleptinemia, higher doses of an mTOR inhibitor, or combination therapy with mTOR and PI3K inhibitors, inhibits neointimal hyperplasia after arterial injury. These studies may explain the higher rates of restenosis observed in diabetics treated with a sirolimus-eluting coronary stent and suggest a potential novel therapeutic approach for inhibiting in-stent restenosis in such patients. metabolic syndrome ͉ vascular disease ͉ neointimal formation ͉ vascular smooth muscle cells

Tonsillectomy is a common otolaryngological procedure and is associated with a small risk of postoperative pharyngeal haemorrhage. This study compares secondary post tonsillectomy haemorrhage rates between two operative techniques: diathermy tonsillectomy and diathermy tonsillectomy with tonsillar bed oversew. A total of 424 patients underwent tonsillectomies with or without other procedures such as adenoidectomy and grommet insertion by two ears, nose and throat surgeons at three hospitals from May 2012 to July 2013. A diathermy tonsillectomy was performed in 266 patients, while a diathermy tonsillectomy with tonsillar bed oversew was performed in 158 patients. All patients were followed up within 2-4 weeks of surgery. Primary haemorrhage did not occur in either surgical technique groups. Secondary haemorrhage occurred in 20 patients (7.52 %) in the diathermy tonsillectomy group and in 9 patients (5.70 %) in the diathermy with tonsillar bed oversew group. This result was not significantly different (OR = 0.74, 95 % CI 0.33-1.67, p = 0.47). Sex, age, indication for surgery and whether or not a tonsillectomy was performed alone or with other procedures were not significant factors for secondary haemorrhage. In summary, routine tonsillar bed oversew after diathermy tonsillectomy does not reduce the risk of secondary tonsillar haemorrhage.