Late dysphagia after radiotherapy-based treatment of head and neck cancer.

BACKGROUND: Changing trends in head and neck cancer (HNC) merit an understanding of the 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 (January 2001 through May 2011). Functional measures included the penetration-aspiration scale (PAS), performance status scale-head and neck (PSS-HN), National Institutes of Health Swallowing Safety Scale (NIH-SSS), and MBS impairment profile (MBSImp). RESULTS: Twenty-nine patients previously treated with radiotherapy (38%) or chemoradiotherapy (62%) were included (median years posttreatment, 9; range, 5-19). The majority (86%) had oropharyngeal cancer; 52% were never-smokers. Seventy-five percent had T2 or T3 tumors; 52% were N+. The 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.

Disruption of the circadian clock within the cardiomyocyte influences myocardial contractile function, metabolism, and gene expression.

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 microM 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.

Circadian rhythms in myocardial metabolism and contractile function: influence of workload and oleate.

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(2)O afterload), hearts were challenged with increased workload (140 cm H(2)O afterload plus 1 microM 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.