Effect of aging on blood flow in rat larynx

A Comparison of the Effects of Acute Whole-Body Vibration for Relieving Vocal Fatigue in Young and Older Adults

PURPOSE

Whole-body vibration (WBV) is a novel treatment to alleviate vocal fatigue, but the evidence in older adults is limited. This study applies WBV in young and older adults to explore how age and vibration duration may influence its relaxation effect.

METHODS

Eighteen older females (mean age 65.56 years) and 18 young females (mean age 22.39 years) with healthy voice participated in karaoke singing to induce vocal fatigue, followed by 15 minutes of WBV. Participants' vocal changes were measured using i) the highest fundamental frequency produced, ii) self-perceived vocal effort, and iii) vocal fatigue level at six timepoints (prevocal loading, postvocal loading, post 5-minute WBV, post 10-minute WBV, post 15-minute WBV, and 15 minutes postWBV completion).

RESULTS

A significant main effect of vibration duration (P < 0.001) and an interaction effect (age x vibration duration) (P < 0.05) were found for self-perceived vocal effort and vocal fatigue level. Both groups showed significant fatigue reduction after receiving 5 minutes of WBV, but recovery slowed down for older adults after receiving WBV for 10 minutes. A significant main effect of age (P < 0.001) was found for the highest fundamental frequency.

CONCLUSION

The results support that WBV may be used in both older and younger adults for vocal fatigue relief.

Techniques, Models, and Variables of Interest in Studies of Intrinsic Laryngeal Muscle Fiber Types: A Bibliometric Analysis

INTRODUCTION

Laryngeal muscle physiology is integral to many speech, voice, swallowing, and respiratory functions. A key determinant of a muscle's contractile properties, including its fatigue profile and capacity for force production, is the myosin heavy chain (MyHC) isoform that predominates in the muscle. This study surveys literature on the MyHC compositions of mammalian intrinsic laryngeal skeletal muscle to illustrate trends and gaps in laryngeal muscle fiber typing techniques, models, and concepts.

METHODS

The Embase, Scopus, Medline, Web of Science, and Cochrane databases were systematically searched for studies of mammalian intrinsic laryngeal muscle MyHC composition. Following Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines for systematic reviews, 1531 non-duplicate papers were identified; 146 were selected for full-text screening. One hundred twenty papers were included in the final bibliometric analysis, which aimed to highlight key concepts in the literature.

RESULTS

Publication of intrinsic laryngeal MyHC studies peaked in the early 2000s and has since declined. Although early research predominantly used histochemical techniques and large mammalian models (cow, sheep, dog, horse, etc), practice has evolved to focus on electrophoretic, immunohistochemical, and transcriptomic fiber typing techniques in rats and humans. Comparatively few studies have examined how experimental manipulations affect laryngeal muscle MyHC composition.

DISCUSSION

Three areas of laryngeal muscle physiology lack a large body of supporting literature: (1) MyHC responses to stimuli such as training and disease, (2) MyHC plasticity across the lifespan, and (3) MyHC heterogeneity within muscle fibers (MyHC polymorphisms) and across muscle fibers (topographical MyHC distribution). We propose new avenues for research, education, and discussion in these three subdomains.

Red Carrot Cells Cultured in vitro Are Effective, Stable, and Safe Ingredients for Skin Care, Nutraceutical, and Food Applications

Plant biomasses growing in bioreactor could be developed as production systems for cosmetic ingredients, nutraceuticals and food additives. We previously reported that the red carrot cell line R4G accumulates high levels of anthocyanins, which are potent antioxidants with multiple health-promoting properties. To investigate the industrial potential of this cell line in detail, we tested extract for antioxidant and anti-inflammatory activity in the mouse monocyte/macrophage cell-line J774A.1 and in reconstructed skin tissue models. We also compared the R4G extract to commercial carrot extracts in terms of stability and metabolomic profiles. We found that the R4G extract have potent antioxidant and anti-inflammatory activities, protecting mammalian cells from the oxidative stress triggered by exposure to bacterial lipopolysaccharides and H₂O₂. The extract also inhibited the nuclear translocation of NF-κB in an epidermal skin model, and induced the expression of VEGF-A to promote the microcirculation in a dermal microtissue model. The anthocyanins extracted from R4G cells were significantly more stable than those found in natural red carrot extracts. Finally, we showed that R4G extract has similar metabolomic profile of natural extracts by using a combination of targeted and untargeted metabolomics analysis, demonstrating the safety of R4G carrot cells for applications in the nutraceutical and food/feed industries.

The Role of Capillaries in the Lesser Ailments of Old Age and in Alzheimer's Disease and Vascular Dementia: The Potential of Pro-Therapeutic Angiogenesis

Apart from chronic diseases (arthritis, diabetes, etc.), old age is generally characterized by three lesser ailments: muscle weakness, minor memory lapses, and cold intolerance. This trio of complaints may have a common, underlying cause, namely, the age-associated reduced microcirculation in muscles, brain, skin, and elsewhere in the body. The Angiogenesis Hypothesis proposes that old age is in part a deficiency disease due to the decline in angiogenic (AG) factors, resulting in a reduced capillary density (CD) throughout the body. Over fifty published papers document waning levels of AG factors and/or decreased CD in various organ systems of aged animals and people, including those with Alzheimer's disease. The deficiency of AG factors is analogous to that of certain hormones (e.g., testosterone) whose blood levels also decline with age. In theory, therapeutic angiogenesis employing recombinant AG factors is a tenable treatment for the lesser ailments of old age and may improve the later years of human life. An optimal administration route may be intranasal.

The effects of treadmill running on aging laryngeal muscle structure

OBJECTIVES/HYPOTHESIS

Age-related changes in laryngeal muscle structure and function may contribute to deficits in voice and swallowing observed in elderly people. We hypothesized that treadmill running, an exercise that increases respiratory drive to upper airway muscles, would induce changes in thyroarytenoid muscle myosin heavy chain (MHC) isoforms that are consistent with a fast-to-slow transformation in muscle fiber type.

STUDY DESIGN

Randomized parallel group controlled trial.

METHODS

Fifteen young adult and 14 old Fischer 344/Brown Norway rats received either treadmill running or no exercise (5 days/week/8 weeks). Myosin heavy chain isoform composition in the thyroarytenoid muscle was examined at the end of 8 weeks.

RESULTS

Significant age and treatment effects were found. The young adult group had the greatest proportion of superfast-contracting MHCIIL isoform. The treadmill running group had the lowest proportion of MHCIIL and the greatest proportion of MHCIIx isoforms.

CONCLUSION

Thyroarytenoid muscle structure was affected both by age and treadmill running in a fast-to-slow transition that is characteristic of exercise manipulations in other skeletal muscles.

LEVEL OF EVIDENCE

NA. Laryngoscope, 126:672-677, 2016.

Changes in Rat 50-kHz Ultrasonic Vocalizations During Dopamine Denervation and Aging: Relevance to Neurodegeneration

Vocal communication is negatively affected by neurodegenerative diseases, such as Parkinson disease, and by aging. The neurological and sensorimotor mechanisms underlying voice deficits in Parkinson disease and aging are not well-understood. Rat ultrasonic vocalizations provide a unique behavioral model for studying communication deficits and the mechanisms underlying these deficits in these conditions. The purpose of this review was to examine the existing literature for methods using rat ultrasonic vocalization with regard to the primary disease pathology of Parkinson disease, dopamine denervation, and aging. Although only a small amount of papers were found for each of these topics, results suggest that both shared and unique acoustic deficits in ultrasonic vocalizations exist across conditions and that these acoustic deficits are due to changes in either dopamine signaling or denervation and in aging models changes to the nucleus ambiguus, at the level of the neuromuscular junction, and the composition of the vocal folds in the larynx. We conclude that ultrasonic vocalizations are a useful tool for studying biologic mechanisms underlying vocal communication deficits in neurodegenerative diseases and aging.

Perioperative Voice Recovery: An Exercise Physiology Perspective

Voice professionals have differing views on the amount of voice rest prescribed before and after laryngeal surgery. Current recommendations are largely based on a long-standing belief that voice rest is good for the vocal mechanism, particularly when pathology is present or following surgical interruption of the vocal fold tissue. There is little evidence to support the benefit of extensive voice rest prior to laryngeal surgery, as is often recommended in the performing arts. In fact, preoperative voice therapy has shown benefit for postoperative voice outcome. From a wound-healing perspective, voice conservation immediately following vocal fold surgery contributes to the best vocal function outcome. There is no supportive evidence for postoperative voice rest that extends for weeks into months, as some performing artists have reported following surgery. From the perspective of skeletal muscle cell physiology and what is currently known about skeletal muscle adaptations that occur with training and detraining, a guideline for optimal voice recovery and return to performance may be clearer. The well-intentioned, long-held belief that extensive voice conservation is good for the voice may actually trigger a skeletal muscle detraining cascade that could lengthen return to optimal voice function, particularly in the vocal performing arts.

Effects of aging on thyroarytenoid muscle regeneration

OBJECTIVES/HYPOTHESIS

Regenerative properties of age-associated changes in the intrinsic laryngeal muscles following injury are unclear. The purpose of this study was to investigate the regenerative properties of the thyroarytenoid (TA) muscle in an aging rat model. The hypothesis was that following myotoxic injury, old animals would exhibit a decrease in mitotic activities of muscle satellite cells when compared with younger rats, suggesting reduced regenerative potential in the aging rat TA muscle.

STUDY DESIGN

Animal group comparison.

METHODS

Regeneration responses following injury to the TA muscle were examined in 18 young adult, middle-aged, and old Fischer 344/Brown Norway rats. TA muscle fiber cross-sectional area (CSA), satellite cell mitosis (number/fiber), and regeneration index (CSA injured side/CSA noninjured side) were measured and compared across age groups.

RESULTS

Young adult animals had a significantly higher regeneration index than the middle-aged and old groups. Within the lateral region of the TA muscle (LTA), the regeneration index was significantly higher in the young adult animals than in the middle-aged and old animals. The regeneration index of the medial TA was significantly higher than the LTA across all age groups.

CONCLUSIONS

The regenerative capacity of the TA muscle is impaired with increasing age.

Translating Exercise Science Into Voice Care

The basic principles of exercise training for skeletal muscle adaptations have been applied to voice training for some time. To date, the use of the basic principles of muscle training for designing a voice rehabilitation program or advising voice clients about the role of voice rest and modified voice use following surgical intervention has not been well developed. Voice training is a complex process of skill acquisition through application of motor learning principles and the concurrent coordinated use of many physiologic systems. However, the translation of exercise science literature to voice training and recovery needs to be undertaken with caution, because the function and performance of laryngeal skeletal muscle can be different from those of skeletal muscles used for other types of movement. This discussion will be confined to the basic adaptations of the muscle tissue itself. A brief review of basic principles of muscle training as understood for skeletal muscle will be followed by a more extensive discussion of the neurologic, metabolic, and physiologic adaptations of muscle training and detraining. Translation of this body of literature will be considered in the contexts of post-surgical voice recovery, voice rehabilitation, and maintenance of professional voice requirements.

Age-related blood flow changes in the rat intrinsic laryngeal muscles

CONCLUSIONS

These results indicate that a deceased laryngeal blood flow (BF) could be one contributing factor to age-related phonatory and airway dysfunction.

OBJECTIVE

Studies of non-laryngeal muscles suggest that decreased BF may contribute to an age-related decline in muscle performance. We hypothesized that there is an age-related BF decrease to the intrinsic laryngeal muscles.

MATERIALS AND METHODS

Intrinsic laryngeal muscle BF was measured in young (3-6 months old; n=11) and old (28-30 months old; n=21) male Fischer 344 rats during quiet respiration using the radiolabeled microsphere technique.

RESULTS

BF to the posterior cricoarytenoid (PCA) was very high even during this submaximal recruitment, consistent with its specialization for oxidative metabolism and fatigue resistance. The results demonstrated significant (p<0.05) age-related BF decreases in the thyroarytenoid (young, 163; old, 64 ml/min/100 g), cricothyroid (young, 104; old, 52 ml/min/100 g), and PCA (young, 404; old, 235 ml/min/100 g).