Virtually every mammalian cell, including cardiomyocytes, possesses an intrinsic circadian clock. The role of this transcriptionally based molecular mechanism in cardiovascular biology is poorly understood. We hypothesized that the circadian clock within the cardiomyocyte influences diurnal variations in myocardial biology. We, therefore, generated a cardiomyocyte-specific circadian clock mutant (CCM) mouse to test this hypothesis. At 12 wk of age, CCM mice exhibit normal myocardial contractile function in vivo, as assessed by echocardiography. Radiotelemetry studies reveal attenuation of heart rate diurnal variations and bradycardia in CCM mice (in the absence of conduction system abnormalities). Reduced heart rate persisted in CCM hearts perfused ex vivo in the working mode, highlighting the intrinsic nature of this phenotype. Wild-type, but not CCM, hearts exhibited a marked diurnal variation in responsiveness to an elevation in workload (80 mmHg plus 1 M epinephrine) ex vivo, with a greater increase in cardiac power and efficiency during the dark (active) phase vs. the light (inactive) phase. Moreover, myocardial oxygen consumption and fatty acid oxidation rates were increased, whereas cardiac efficiency was decreased, in CCM hearts. These observations were associated with no alterations in mitochondrial content or structure and modest mitochondrial dysfunction in CCM hearts. Gene expression microarray analysis identified 548 and 176 genes in atria and ventricles, respectively, whose normal diurnal expression patterns were altered in CCM mice. These studies suggest that the cardiomyocyte circadian clock influences myocardial contractile function, metabolism, and gene expression.

Background Changing trends in head and neck cancer (HNC) merit an understanding of late effects of therapy, but few studies examine dysphagia beyond 2 years of treatment. Methods A case series was examined to describe the pathophysiology and outcomes in dysphagic HNC survivors referred for modified barium swallow (MBS) studies ≥5 years after definitive radiotherapy or chemoradiotherapy (01/2001–05/2011). Functional measures included the Penetration-Aspiration Scale (PAS), Performance Status Scale-Head and Neck (PSS-HN), Swallowing Safety Scale (NIH-SSS), and MBSImp. Results Twenty-nine patients previously treated with radiotherapy (38%) or chemoradiotherapy (62%) were included (median years post-treatment: 9, range: 5–19). The majority (86%) had oropharyngeal cancer; 52% were never smokers. Seventy-five percent had T2-T3 disease; 52% were N+. Median age at diagnosis was 55 (range: 38–72). Abnormal late examination findings included: dysarthria/dysphonia (76%), cranial neuropathy (48%), trismus (38%), and radionecrosis (10%). MBS studies confirmed pharyngeal residue and aspiration in all dysphagic cases owing to physiologic impairment (median PAS: 8; median NIH-SSS: 10; median MBSImp: 18) whereas stricture was confirmed endoscopically in 7 (24%). Twenty-five (86%) developed pneumonia, half requiring hospitalization. Swallow postures/strategies helped 69% of cases, but no patient achieved durable improvement across functional measures at last follow-up. Ultimately 19 (66%) were gastrostomy dependent. Conclusions Although functional organ preservation is commonly achieved, severe dysphagia represents a challenging late effect that may develop or progress years after radiation-based therapy for HNC. These data suggest that novel approaches are needed to minimize and better address this complication that is commonly refractory to many standard dysphagia therapies.

ME. Circadian rhythms in myocardial metabolism and contractile function: influence of workload and oleate. Am J Physiol Heart Circ Physiol 293: H2385-H2393, 2007. First published July 6, 2007; doi:10.1152/ajpheart.01361.2006.-Multiple extracardiac stimuli, such as workload and circulating nutrients (e.g., fatty acids), known to influence myocardial metabolism and contractile function exhibit marked circadian rhythms. The aim of the present study was to investigate whether the rat heart exhibits circadian rhythms in its responsiveness to changes in workload and/or fatty acid (oleate) availability. Thus, hearts were isolated from male Wistar rats (housed during a 12:12-h light-dark cycle: lights on at 9 AM) at 9 AM, 3 PM, 9 PM, and 3 AM and perfused in the working mode ex vivo with 5 mM glucose plus either 0.4 or 0.8 mM oleate. Following 20-min perfusion at normal workload (i.e., 100 cm H 2O afterload), hearts were challenged with increased workload (140 cm H 2O afterload plus 1 M epinephrine). In the presence of 0.4 mM oleate, myocardial metabolism exhibited a marked circadian rhythm, with decreased rates of glucose oxidation, increased rates of lactate release, decreased glycogenolysis capacity, and increased channeling of oleate into nonoxidative pathways during the light phase. Rat hearts also exhibited a modest circadian rhythm in responsiveness to the workload challenge when perfused in the presence of 0.4 mM oleate, with increased myocardial oxygen consumption at the dark-to-light phase transition. However, rat hearts perfused in the presence of 0.8 mM oleate exhibited a markedly blunted contractile function response to the workload challenge during the light phase. In conclusion, these studies expose marked circadian rhythmicities in myocardial oxidative and nonoxidative metabolism as well as responsiveness of the rat heart to changes in workload and fatty acid availability. fatty acids; glucose; glycogen; triglyceride CIRCADIAN RHYTHMS IN CARDIOVASCULAR PHYSIOLOGY and pathophysiology are well established. Heart rate, blood pressure, cardiac output, platelet aggregability, myocardial infarction, arrhythmias, and sudden cardiac death all exhibit marked circadian rhythmicities in both humans and animal models (3,7,12,18,23,33). To date, these observations have been attributed primarily to diurnal variations in multiple extracellular stimuli (i.e., neurohumoral factors) such as autonomic and sympathetic activity (23,24,32). However, it is becoming increasingly clear that the intrinsic properties of cardiovascular components change over the course of the day, suggesting that oscillations in responsiveness to extracellular stimuli may contribute toward circadian rhythmicities in cardiovascular events (36, 37).Myocardial metabolism and contractile function are inextricably interlinked. For example, increased energy demand during periods of elevated workload is balanced by increased oxidative and nonoxidative metabolism (17). An inability of the heart to maintain adequate ATP supply will in turn adversely affect...

Recently, a transoral robotic-assisted technique to access the thyroid gland has been introduced. Despite the advantages this approach may have over other minimally invasive and robotic-assisted techniques, we found that the placement of the camera through the floor of mouth led to restricted freedom of movement. We describe our modification to this technique to overcome this problem. In a study using two fresh human cadavers, the camera port of the da Vinci robot was placed in the midline oral vestibule instead of the floor of the mouth. A transoral thyroidectomy and central neck dissection was successfully performed. Our modification led to an unfettered view of the central neck and allowed for a total thyroidectomy and central neck dissection. Our modification of transoral robotic-assisted thyroidectomy provides superior access to the central compartment of the neck over other robotic-assisted thyroidectomy techniques.Electronic supplementary materialThe online version of this article (doi:10.1007/s11701-011-0287-2) contains supplementary material, which is available to authorized users.

Meiotic development in Saccharomyces cerevisiae (sporulation) is controlled by the sequential transcription of temporally distinct sets of meiosis-specific genes. The induction of middle genes controls exit from meiotic prophase, the completion of the nuclear divisions, and spore formation. Middle promoters are controlled through DNA elements termed middle sporulation elements (MSEs) that are bound by the Sum1 repressor during vegetative growth and by the Ndt80 activator during meiosis. It has been proposed that the induction of middle promoters is controlled by competition between Ndt80 and Sum1 for MSE occupancy. Here, we show that the Sum1 repressor can be removed from middle promoters in meiotic cells independent of Ndt80 expression. This process requires the phosphorylation of Sum1 by the meiosis-specific cyclin-dependent kinase-like kinase Ime2. The deletion of HST1, which encodes a Sir2 paralog that interacts with Sum1, bypasses the requirement for this phosphorylation. These findings suggest that in the presence of Ndt80, Sum1 may be displaced from MSEs through a competition-based mechanism but that in the absence of Ndt80, Sum1 is removed from chromatin in a separate pathway requiring the phosphorylation of Sum1 by Ime2 and the inhibition of Hst1.Meiotic development is the pathway that produces haploid gametes from diploid precursors. Following the induction of the pathway, cells duplicate the genome and then enter an elongated prophase when homolog pairing, synapsis, and genetic recombination take place. Exit from prophase is followed by two sequential rounds of chromosome segregation. In many organisms, exit from prophase is a key control point where meiotic progression is regulated.Meiotic development in the yeast Saccharomyces cerevisiae (sporulation) is tightly regulated by a transcriptional program. The transcriptional program of sporulation is characterized by the sequential expression of temporally distinct sets of genes that are induced as different steps in the program take place (5, 30). Although there are at least 12 temporally distinct subclasses of sporulation-specific genes, they can be broadly grouped into early, middle, and late classes (reviewed in reference 39).Early promoters are activated by the Ime1 transcription factor, which is expressed and activated in diploids in response to starvation signals (reviewed in references 13 and 39). Early genes are expressed throughout meiotic S phase and prophase (5, 30). Toward the end of prophase, at the pachytene stage, homologs are fully connected by synaptonemal complexes (SCs), joint molecules have been formed but crossover recombinants have not been resolved (1, 24), and the spindle pole body (centrosome) has duplicated in preparation for the first meiotic division (3, 43).Exit from pachytene, entry into the meiotic divisions, and spore formation require the induction of middle genes. Middle promoters are activated by the Ndt80 transcription factor, which specifically binds to DNA elements termed middle sporulation elements (MSEs) (6,8). n...