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Mu L, Chen J, Nyirenda T, Li J, Sobotka S, Benson B, Christopherson M, Sanders I. Morphometric and Immunohistochemical Characteristics of the Adult Human Soft Palate Muscles. J Histochem Cytochem 2022; 70:225-236. [PMID: 34957888 PMCID: PMC8832629 DOI: 10.1369/00221554211066985] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
The soft palate is the only structure that reversibly separates the respiratory and gastrointestinal systems. Most species can eat and breathe at the same time. Humans cannot do this and malfunction of the soft palate may allow food to enter the lungs and cause fatal aspiration pneumonia. Speech is the most defining characteristic of humans and the soft palate, along with the larynx and tongue, plays the key roles. In addition, palatal muscles are involved in snoring and obstructive sleep apnea. Considering the significance of the soft palate, its function is insufficiently understood. The objectives of this study were to document morphometric and immunohistochemical characteristics of adult human soft palate muscles, including fiber size, the fiber type, and myosin heavy chain (MyHC) composition for better understanding muscle functions. In this study, 15 soft palates were obtained from human autopsies. The palatal muscles were separated, cryosectioned, and stained using histological and immunohistochemical techniques. The results showed that there was a fast type II predominance in the musculus uvulae and palatopharyngeus and a slow type I predominance in the levator veli palatine. Approximately equal proportions of type I and type II fibers existed in both the palatoglossus and tensor veli palatine. Soft palate muscles also contained hybrid fibers and some specialized myofibers expressing slow-tonic and embryonic MyHC isoforms. These findings would help better understand muscle functions.
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Affiliation(s)
- Liancai Mu
- Liancai Mu, Upper Airway Research Laboratory, Center for Discovery and Innovation, Hackensack Meridian Health, 111 Ideation Way, Nutley, NJ 07110, USA. E-mail:
| | - Jingming Chen
- Upper Airway Research Laboratory, Center for Discovery and Innovation, Hackensack Meridian Health, Nutley, New Jersey
| | - Themba Nyirenda
- Upper Airway Research Laboratory, Center for Discovery and Innovation, Hackensack Meridian Health, Nutley, New Jersey
| | - Jing Li
- Upper Airway Research Laboratory, Center for Discovery and Innovation, Hackensack Meridian Health, Nutley, New Jersey
| | - Stanislaw Sobotka
- Department of Otolaryngology, Icahn School of Medicine at Mount Sinai, New York City, New York,Upper Airway Research Laboratory, Center for Discovery and Innovation, Hackensack Meridian Health, Nutley, New Jersey
| | - Brian Benson
- Department Otolaryngology, Hackensack University Medical Center, Hackensack, New Jersey
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BaHammam AS, Aleissi S, Olaish AH, Almeneessier AS, Jammah AA. Prevalence of Hypothyroidism in a Large Sample of Patients with Obesity Hypoventilation Syndrome. Nat Sci Sleep 2020; 12:649-659. [PMID: 32982523 PMCID: PMC7505711 DOI: 10.2147/nss.s263959] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/29/2020] [Accepted: 08/24/2020] [Indexed: 01/18/2023] Open
Abstract
PURPOSE Data on hypothyroidism in patients with obesity hypoventilation syndrome (OHS) are scarce. This study assessed the prevalence of hypothyroidism among a large group of patients with OHS. PATIENTS AND METHODS This was a prospective observational study of 308 consecutive patients with OHS seen between January 2002 and December 2018. Serum thyroid-stimulating hormone (TSH) and free-thyroxine (FT4) levels were measured in all patients. The OHS patients were compared with 445 patients with obstructive sleep apnoea (OSA) matched for age, sex, and body mass index (BMI). RESULTS The OHS patients had a mean age of 55.1 ± 13.8 years and a BMI of 43.9 ± 14.8 kg/m2; apnoea hypopnea index was ≥30 events/hr in 222 (72%). Clinical hypothyroidism was diagnosed in 58 (18.8%) of the OHS patients; only two cases (0.6%) were diagnosed in the sleep disorders clinic (newly diagnosed cases). Subclinical hypothyroidism was diagnosed in 19 (6.2%) of the OHS patients based on elevated TSH and normal FT4 levels; all cases were newly diagnosed. A logistic regression model identified female sex as the only predictor of clinical hypothyroidism in OHS patients (odds ratio: 2.801 [1.386-5.662], p = 0.004). There was no significant difference in clinical hypothyroidism prevalence between the OHS and OSA patients; however, subclinical hypothyroidism was more common in OHS than in OSA patients (6.2% vs 2.9%, respectively, p = 0.03). CONCLUSION Clinical hypothyroidism was prevalent among patients with OHS; however, newly diagnosed cases of clinical hypothyroidism were relatively low. Female sex was the only predictor of clinical hypothyroidism.
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Affiliation(s)
- Ahmed S BaHammam
- University Sleep Disorders Center, College of Medicine, King Saud University, Riyadh, Saudi Arabia.,Strategic Technologies Program of the National Plan for Sciences and Technology and Innovation in the Kingdom of Saudi Arabia, Riyadh, Saudi Arabia
| | - Salih Aleissi
- University Sleep Disorders Center, College of Medicine, King Saud University, Riyadh, Saudi Arabia
| | - Awad H Olaish
- University Sleep Disorders Center, College of Medicine, King Saud University, Riyadh, Saudi Arabia
| | - Aljohara S Almeneessier
- University Sleep Disorders Center, College of Medicine, King Saud University, Riyadh, Saudi Arabia.,Family and Community Medicine, College of Medicine, King Saud University, Riyadh, Saudi Arabia
| | - Anwar A Jammah
- Endocrinology Unit, Thyroid Diseases Section, Department of Medicine, King Saud University, Riyadh, Saudi Arabia
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Thometz NM, Dearolf JL, Dunkin RC, Noren DP, Holt MM, Sims OC, Cathey BC, Williams TM. Comparative physiology of vocal musculature in two odontocetes, the bottlenose dolphin (Tursiops truncatus) and the harbor porpoise (Phocoena phocoena). J Comp Physiol B 2017; 188:177-193. [PMID: 28569355 DOI: 10.1007/s00360-017-1106-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2017] [Accepted: 05/11/2017] [Indexed: 10/19/2022]
Abstract
The mechanism by which odontocetes produce sound is unique among mammals. To gain insight into the physiological properties that support sound production in toothed whales, we examined myoglobin content ([Mb]), non-bicarbonate buffering capacity (β), fiber-type profiles, and myosin heavy chain expression of vocal musculature in two odontocetes: the bottlenose dolphin (Tursiops truncatus; n = 4) and the harbor porpoise (Phocoena phocoena; n = 5). Both species use the same anatomical structures to produce sound, but differ markedly in their vocal repertoires. Tursiops produce both broadband clicks and tonal whistles, while Phocoena only produce higher frequency clicks. Specific muscles examined in this study included: (1) the nasal musculature around the phonic lips on the right (RNM) and left (LNM) sides of the head, (2) the palatopharyngeal sphincter (PPS), which surrounds the larynx and aids in pressurizing cranial air spaces, and (3) the genioglossus complex (GGC), a group of muscles positioned ventrally within the head. Overall, vocal muscles had significantly lower [Mb] and β than locomotor muscles from the same species. The PPS was predominately composed of small diameter slow-twitch fibers. Fiber-type and myosin heavy chain analyses revealed that the GGC was comprised largely of fast-twitch fibers (Tursiops: 88.6%, Phocoena: 79.7%) and had the highest β of all vocal muscles. Notably, there was a significant difference in [Mb] between the RNM and LNM in Tursiops, but not Phocoena. Our results reveal shared physiological characteristics of individual vocal muscles across species that enhance our understanding of key functional roles, as well as species-specific differences which appear to reflect differences in vocal capacities.
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Affiliation(s)
- Nicole M Thometz
- Department of Biology, University of San Francisco, 2130 Fulton St, San Francisco, CA, 94117, USA. .,Department of Ecology and Evolutionary Biology, Long Marine Laboratory, University of California at Santa Cruz, 115 McAllister Way, Santa Cruz, CA, 95060, USA.
| | - Jennifer L Dearolf
- Biology Department, Hendrix College, 1600 Washington Ave., Conway, AR, 72032, USA
| | - Robin C Dunkin
- Department of Ecology and Evolutionary Biology, Long Marine Laboratory, University of California at Santa Cruz, 115 McAllister Way, Santa Cruz, CA, 95060, USA
| | - Dawn P Noren
- Conservation Biology Division, Northwest Fisheries Science Center, National Marine Fisheries Service, National Oceanic and Atmospheric Administration, 2725 Montlake Boulevard East, Seattle, WA, 98112, USA
| | - Marla M Holt
- Conservation Biology Division, Northwest Fisheries Science Center, National Marine Fisheries Service, National Oceanic and Atmospheric Administration, 2725 Montlake Boulevard East, Seattle, WA, 98112, USA
| | - Olivia C Sims
- Biology Department, Hendrix College, 1600 Washington Ave., Conway, AR, 72032, USA
| | - Brandon C Cathey
- Biology Department, Hendrix College, 1600 Washington Ave., Conway, AR, 72032, USA
| | - Terrie M Williams
- Department of Ecology and Evolutionary Biology, Long Marine Laboratory, University of California at Santa Cruz, 115 McAllister Way, Santa Cruz, CA, 95060, USA
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Rhee HS, Hoh JFY. Immunohistochemical analysis of the effects of cross-innervation of murine thyroarytenoid and sternohyoid muscles. J Histochem Cytochem 2010; 58:1057-65. [PMID: 20713983 DOI: 10.1369/jhc.2010.956706] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
This work uses cross-innervation of respiratory muscles of different developmental origins to probe myogenic and neurogenic mechanisms regulating their fiber types. The thyroarytenoid (TA) originates from the sixth branchial arch, whereas the sternohyoid (SH) is derived from somitic mesoderm. Immunohistochemical analysis using highly specific monoclonal antibodies to myosin heavy chain (MyHC) isoforms reveals that normal rat SH comprises slow, 2a, 2x, and 2b fibers, as in limb fast muscles, whereas the external division of the TA has only 2b/eo fibers coexpressing 2B and extraocular (EO) MyHCs. Twelve weeks after cross-innervation with the recurrent laryngeal nerve, the SH retained slow and 2a fibers, greatly increased the proportion of 2x fibers, and their 2b fibers failed to express EO MyHC. In the cross-innervated TA, the SH nerve failed to induce slow and 2A MyHC expression and failed to suppress EO MyHC expression in 2b/eo fibers. However, 2x fibers amounting to 4.2% appeared de novo in the external division of the TA. We conclude that although MyHC gene expression in these muscles can be modulated by neural activity, the patterns of response to altered innervation are largely myogenically determined, thus supporting the idea that SH and TA differ in muscle allotype.
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Affiliation(s)
- Hannah S Rhee
- Discipline of Physiology, Building F13, Sydney Medical School, The University of Sydney, Sydney, New South Wales 2006, Australia
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Zhong WWH, Withers KW, Hoh JFY. Effects of hypothyroidism on myosin heavy chain composition and fibre types of fast skeletal muscles in a small marsupial, Antechinus flavipes. J Comp Physiol B 2009; 180:531-44. [PMID: 20012435 DOI: 10.1007/s00360-009-0431-8] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2009] [Revised: 11/02/2009] [Accepted: 11/25/2009] [Indexed: 11/29/2022]
Abstract
Effects of drug-induced hypothyroidism on myosin heavy chain (MyHC) content and fibre types of fast skeletal muscles were studied in a small marsupial, Antechinus flavipes. SDS-PAGE of MyHCs from the tibialis anterior and gastrocnemius revealed four isoforms, 2B, 2X, 2A and slow, in that order of decreasing abundance. After 5 weeks treatment with methimazole, the functionally fastest 2B MyHC significantly decreased, while 2X, 2A and slow MyHCs increased. Immunohistochemistry using monospecific antibodies to each of the four MyHCs revealed decreased 2b and 2x fibres, and increased 2a and hybrid fibres co-expressing two or three MyHCs. In the normally homogeneously fast superficial regions of these muscles, evenly distributed slow-staining fibres appeared, resembling the distribution of slow primary myotubes in fast muscles during development. Hybrid fibres containing 2A and slow MyHCs were virtually absent. These results are more detailed but broadly similar to the earlier studies on eutherians. We hypothesize that hypothyroidism essentially reverses the effects of thyroid hormone on MyHC gene expression of muscle fibres during myogenesis, which differ according to the developmental origin of the fibre: it induces slow MyHC expression in 2b fibres derived from fast primary myotubes, and shifts fast MyHC expression in fibres of secondary origin towards 2A, but not slow, MyHC.
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Affiliation(s)
- Wendy W H Zhong
- Discipline of Physiology and the Bosch Institute, Bldg F13, Sydney Medical School, The University of Sydney, Sydney, NSW 2006, Australia
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Sacerdote A, Weiss K, Tran T, Rokeya Noor B, McFarlane SI. Hypertension in patients with cushing’s disease: Pathophysiology, diagnosis, and management. Curr Hypertens Rep 2005; 7:212-8. [PMID: 15913497 DOI: 10.1007/s11906-005-0013-4] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
Abstract
Hypertension is a very common comorbidity in patients with Cushing's disease/syndrome, resulting from the interplay of several pathophysiologic mechanisms, including stimulation of mineralocorticoid and glucocorticoid receptors as well as the associated insulin resistance, sleep apnea, and overexpression of renin-angiotensin system. Although treatment of Cushing's disease results in resolution or amelioration of hypertension in these patients, a significant proportion of patients do not achieve complete cure or require a prolonged period of time for complete response to therapy. Therefore, therapeutic strategies for Cushing's-specific hypertension are necessary to decrease morbidity and mortality associated with this disease. In this review, we discuss the pathophysiology of hypertension in patients with Cushing's disease, highlighting the therapeutic options, including the exciting new developments in the role of peroxisome proliferator-activated receptor (PPAR)-g agonists in the management of this patient population.
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Affiliation(s)
- Alan Sacerdote
- Department of Medicine, S.U.N.Y. Health Science Center at Brooklyn, 450 Clarkson Avenue, Brooklyn, NY 11203, USA
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Mu L, Su H, Wang J, Han Y, Sanders I. Adult human mylohyoid muscle fibers express slow-tonic, alpha-cardiac, and developmental myosin heavy-chain isoforms. ACTA ACUST UNITED AC 2004; 279:749-60. [PMID: 15278946 DOI: 10.1002/ar.a.20065] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
Some adult cranial muscles have been reported to contain unusual myosin heavy-chain (MHC) isoforms (i.e., slow-tonic, alpha-cardiac, embryonic, and neonatal), which exhibit distinct contractile properties. In this study, adult human mylohyoid (MH) muscles obtained from autopsies were investigated to detect the unusual MHC isoforms. For comparison, the biceps brachii and masseter muscles of the same subjects were also examined. Serial cross-sections from the muscles studied were incubated with a panel of isoform-specific anti-MHC monoclonal antibodies that distinguish major and unusual MHC isoforms. On average, the slow type I and fast type II MHC-containing fibers in the MH muscle accounted for 54% and 46% of the fibers, respectively. In contrast to limb and trunk muscles, the adult human MH muscle was characterized by a large proportion of hybrid fibers (85%) and a small percentage of pure fibers (15%; P < 0.01). Of the fast fiber types, the proportion of the type IIa MHC-containing fibers (92%) was much greater than that of the type IIx MHC-containing fibers (8%; P < 0.01). Our data demonstrated that the adult human MH fibers expressed the unusual MHC isoforms that were also identified in the masseter, but not in the biceps brachii. These isoforms were demonstrated by immunocytochemistry and confirmed by electrophoretic immunoblotting. Fiber-to-fiber comparisons showed that the unusual MHC isoforms were coexpressed with the major MHC isoforms (i.e., MHCI, IIa, and IIx), thus forming various major/unusual (or m/u) MHC hybrid fiber types. Interestingly, the unusual MHC isoforms were expressed in a fiber type-specific manner. The slow-tonic and alpha-cardiac MHC isoforms were coexpressed predominantly with slow type I MHC isoform, whereas the developmental MHC isoforms (i.e., embryonic and neonatal) coexisted primarily with fast type IIa MHC isoform. There were no MH fibers that expressed exclusively unusual MHC isoforms. Approximately 81% of the slow type I MHC-containing fibers expressed slow-tonic and alpha-cardiac MHC isoforms, whereas 80% of the fast type IIa MHC-containing fibers expressed neonatal MHC isoform. The m/u hybrid fibers (82% of the total fiber population) were found to constitute the predominant fiber types in the adult human MH muscle. At least seven m/u MHC hybrid fiber types were identified in the adult human MH muscle. The most common m/u hybrid fiber types were found to be the MHCI/slow-tonic/alpha-cardiac and MHCIIa/neonatal, which accounted for 39% and 33% of the total fiber population, respectively. The multiplicity of MHC isoforms in the adult MH fibers is believed to be related to embryonic origin, innervation pattern, and unique functional requirements.
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Affiliation(s)
- Liancai Mu
- Department of Otolaryngology, Mount Sinai Medical Center, New York, NY 10029, USA.
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Kim DK, Zhu J, Kozyak BW, Burkman JM, Rubinstein NA, Lankford EB, Stedman HH, Nguyen T, Levine S, Shrager JB. Myosin heavy chain and physiological adaptation of the rat diaphragm in elastase-induced emphysema. Respir Res 2003; 4:1. [PMID: 12617755 PMCID: PMC150515 DOI: 10.1186/rr196] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2002] [Revised: 10/11/2002] [Accepted: 11/01/2002] [Indexed: 03/01/2023] Open
Abstract
BACKGROUND Several physiological adaptations occur in the respiratory muscles in rodent models of elastase-induced emphysema. Although the contractile properties of the diaphragm are altered in a way that suggests expression of slower isoforms of myosin heavy chain (MHC), it has been difficult to demonstrate a shift in MHCs in an animal model that corresponds to the shift toward slower MHCs seen in human emphysema. METHODS We sought to identify MHC and corresponding physiological changes in the diaphragms of rats with elastase-induced emphysema. Nine rats with emphysema and 11 control rats were studied 10 months after instillation with elastase. MHC isoform composition was determined by both reverse transcriptase polymerase chain reaction (RT-PCR) and immunocytochemistry by using specific probes able to identify all known adult isoforms. Physiological adaptation was studied on diaphragm strips stimulated in vitro. RESULTS In addition to confirming that emphysematous diaphragm has a decreased fatigability, we identified a significantly longer time-to-peak-tension (63.9 +/- 2.7 ms versus 53.9 +/- 2.4 ms). At both the RNA (RT-PCR) and protein (immunocytochemistry) levels, we found a significant decrease in the fastest, MHC isoform (IIb) in emphysema. CONCLUSION This is the first demonstration of MHC shifts and corresponding physiological changes in the diaphragm in an animal model of emphysema. It is established that rodent emphysema, like human emphysema, does result in a physiologically significant shift toward slower diaphragmatic MHC isoforms. In the rat, this occurs at the faster end of the MHC spectrum than in humans.
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Affiliation(s)
- Dong Kwan Kim
- Department of Surgery, University of Pennsylvania School of Medicine, Philadelphia, Pennsylvania, USA
- Present address: Asan Medical Center, University of Ulsan College of Medicine, Seoul, Korea
| | - Jianliang Zhu
- Department of Surgery, University of Pennsylvania School of Medicine, Philadelphia, Pennsylvania, USA
| | - Benjamin W Kozyak
- Department of Surgery, University of Pennsylvania School of Medicine, Philadelphia, Pennsylvania, USA
| | - James M Burkman
- Department of Surgery, University of Pennsylvania School of Medicine, Philadelphia, Pennsylvania, USA
| | - Neal A Rubinstein
- Pennsylvania Muscle Institute, University of Pennsylvania School of Medicine, Philadelphia, Pennsylvania, USA
| | - Edward B Lankford
- Department of Pathology, Anatomy and Cell Biology, Thomas Jefferson University, Philadelphia, Pennsylvania, USA
| | - Hansell H Stedman
- Department of Surgery, University of Pennsylvania School of Medicine, Philadelphia, Pennsylvania, USA
- Pennsylvania Muscle Institute, University of Pennsylvania School of Medicine, Philadelphia, Pennsylvania, USA
- Department of Surgery, Philadelphia Veterans Affairs Medical Center, Philadelphia, Pennsylvania, USA
| | - Taitan Nguyen
- Department of Medicine, Philadelphia Veterans Affairs Medical Center, Philadelphia, Pennsylvania, USA
| | - Sanford Levine
- Pennsylvania Muscle Institute, University of Pennsylvania School of Medicine, Philadelphia, Pennsylvania, USA
- Department of Medicine, Philadelphia Veterans Affairs Medical Center, Philadelphia, Pennsylvania, USA
| | - Joseph B Shrager
- Department of Surgery, University of Pennsylvania School of Medicine, Philadelphia, Pennsylvania, USA
- Pennsylvania Muscle Institute, University of Pennsylvania School of Medicine, Philadelphia, Pennsylvania, USA
- Department of Surgery, Philadelphia Veterans Affairs Medical Center, Philadelphia, Pennsylvania, USA
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10
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Van Lunteren E, Kaminski HJ. Disorders of Sleep and Breathing during Sleep in Neuromuscular Disease. Sleep Breath 2002; 3:23-30. [PMID: 11898100 DOI: 10.1007/s11325-999-0023-6] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
Affiliation(s)
- Erik Van Lunteren
- Departments of Medicine and Neurology, Cleveland VA Medical Center and Case Western Reserve University, Cleveland, Ohio
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11
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Oliven A, Carmi N, Coleman R, Odeh M, Silbermann M. Age-related changes in upper airway muscles morphological and oxidative properties. Exp Gerontol 2001; 36:1673-86. [PMID: 11672988 DOI: 10.1016/s0531-5565(01)00127-9] [Citation(s) in RCA: 36] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
Obstructive sleep apnea (OSA) is a common disorder of the middle aged and elderly. It results from the decrease in upper airway muscle (UAM) tone that occurs during sleep. It is unclear whether age-related changes in UAM could constitute a contributory mechanism to the increased prevalence of OSA with increasing age, and previous papers evaluating the effects of aging on UAM in rats reported conflicting results. In the present study, we compared, in four age groups of Wistar rats (6-24 months), fiber-type distribution, mean cross-sectional fiber area and succinate dehydrogenase optical density of dilating and non-dilating UAM, and the diaphragm. Succinate dehydrogenase optical density, a marker of oxidative capacity, decreased significantly after the age of 6 months in all muscles (except for the sternohyoid), particularly in the genioglossus, the main tongue protrudor. In this muscle, we also found a significant decrease in type IIa and an increase in IIb fibers after the age of 18 months. Age-related changes in fiber-type distribution in other muscles were mostly insignificant. Dilating UAM could not be distinguished from their non-dilating neighboring muscles by their histochemical properties or aging-related changes. The aging-related changes observed in the present study may decrease UAM endurance, particularly that of the main tongue protrudor, the genioglossus.
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Affiliation(s)
- A Oliven
- Department of Internal Medicine B, Bnai Zion Medical Center, Department of Anatomy and Cell Biology, Bruce Rappaport Faculty of Medicine, Technion, Golomb Str. 47, Haifa 34466, Israel.
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12
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Abstract
Five muscle fibre types (I, IIc, IIa, IIx and IIb) were found in the suprahyoid muscles (mylohyoid, geniohyoid, and the anterior and posterior bellies of the digastric) of the rat using immuno and enzyme histochemical techniques. More than 90% of fibres in the muscles examined were fast contracting fibres (types IIa, IIx and IIb). The geniohyoid and the anterior belly of the digastric had the greatest number of IIb fibres, whilst the mylohyoid was almost exclusively formed by aerobic fibres. The posterior belly of the digastric contained a greater percentage of aerobic fibres (83.4%) than the anterior belly (67.8%). With the exception of the geniohyoid, the percentage of type I and IIc fibres, which have slow myosin heavy chain (MHCbeta), was relatively high and greater than has been previously reported in the jaw-closing muscles of the rat, such as the superficial masseter. The geniohyoid and mylohyoid exhibited a mosaic fibre type distribution, without any apparent regionalisation, although in the later MHCbeta-containing fibres (types I and IIc) were primarily located in the rostral 2/3 region. In contrast, the anterior and posterior bellies of the digastric revealed a clear regionalisation. In the anterior belly of the digastric 2 regions were observed: both a central region, which was almost exclusively formed by aerobic fibres and where all of the type I and IIc fibres were located, and a peripheral region, where type IIb fibres predominated. The posterior belly of the digastric showed a deep aerobic region which was greater in size and where type I and IIc fibres were confined, and a superficial region, where primarily type IIx and IIb fibres were observed.
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Affiliation(s)
- A R Cobos
- Department of Morphological Sciences, Faculty of Medicine and Odontology, University of Santiago de Compostela, Spain
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Eason JM, Schwartz GA, Pavlath GK, English AW. Sexually dimorphic expression of myosin heavy chains in the adult mouse masseter. J Appl Physiol (1985) 2000; 89:251-8. [PMID: 10904059 DOI: 10.1152/jappl.2000.89.1.251] [Citation(s) in RCA: 76] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Little is known regarding the role of androgenic hormones in the maintenance of myosin heavy chain (MHC) composition of rodent masticatory muscles. Because the masseter is the principal jaw closer in rodents, we felt it was important to characterize the influence of androgenic hormones on the MHC composition of the masseter. To determine the extent of sexual dimorphism in the phenotype of masseter muscle fibers of adult (10-mo-old) C57 mice, we stained tissue sections with antibodies specific to type IIa and IIb MHC isoforms. Females contain twice as many fibers containing the IIa MHC as males, and males contain twice as many fibers containing the IIb MHC as females. There is a modest amount of regionalization of MHC phenotypes in the mouse masseter. The rostral portions of the masseter are composed mostly of type IIa fibers, whereas the midsuperficial and caudal regions contain mostly type IIb fibers. Using immunoblots, we showed that castration results in an increase in the expression of type IIa MHC fibers in males. Ovariectomy has no effect on the fiber type composition in females. We conclude that testosterone plays a role in the maintenance of MHC expression in the adult male mouse masseter.
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Affiliation(s)
- J M Eason
- Department of Cell Biology, Emory University School of Medicine, Atlanta, Georgia 30322, USA.
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Sutlive TG, Shall MS, McClung JR, Goldberg SJ. Contractile properties of the tongue's genioglossus muscle and motor units in the rat. Muscle Nerve 2000; 23:416-25. [PMID: 10679719 DOI: 10.1002/(sici)1097-4598(200003)23:3<416::aid-mus14>3.0.co;2-#] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
The contractile characteristics of individual mammalian tongue muscles have rarely been investigated, in contrast to spinal cord-innervated and extraocular muscles. Therefore, whole muscle and motor unit contractile forces, plus muscle fiber types, were studied in the genioglossus, the major protrusor muscle, of the rat tongue. The muscle, exclusively composed of fast-contracting units, could be activated from rostroventral hypoglossal nucleus sites only. The following figures represent the means of the contractile measures. Whole muscle twitch tension was 7.02 g, contraction time was 14.22 ms, fusion frequency was 104 Hz, maximum tetanic tension was 37.22 g, and fatigue index was 0.72. Single motor unit twitch tension was 45. 9 mg, contraction time was 11.7 ms, fusion frequency was 94.8 Hz, maximum tetanic tension was 241.95 mg, and fatigue index was 0.68. The genioglossus muscle appeared qualitatively similar to the rat styloglossus muscle, one of the two major retractor muscles of the tongue. The delineation of motor unit contractile characteristics in tongue muscle is important in our understanding of the control of tongue movement.
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Affiliation(s)
- T G Sutlive
- Department of Anatomy Virginia Commonwealth University, MCV Campus, POB 980709, Richmond, Virginia 23298-0709, USA
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Yang L, Bourdon J, Gottfried SB, Zin WA, Petrof BJ. Regulation of myosin heavy chain gene expression after short-term diaphragm inactivation. THE AMERICAN JOURNAL OF PHYSIOLOGY 1998; 274:L980-9. [PMID: 9609737 DOI: 10.1152/ajplung.1998.274.6.l980] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
Although prolonged diaphragm denervation (DNV) produces myofiber atrophy and a loss of type I myosin heavy chain (MHC) expression, short-term DNV leads to significant diaphragm hypertrophy. The purpose of this study was to explore the regulation of MHC isoform expression and muscle remodeling during DNV hypertrophy of the diaphragm. Both unilateral and bilateral DNV led to similar changes, with a significant increase in total RNA content and muscle mass but no change in dry-to-wet weight ratio. Sarcomere number was also increased in diaphragm myofibers after DNV ( approximately 20%), suggesting an adaptive response to muscle stretch. There was hypertrophy of type I myofibers and increased coexpression of type I and type II MHCs within single myofibers by immunocytochemistry as well as increased type I MHC (25-46%) and decreased type IIb MHC (14-39%) by SDS-PAGE. Contractility parameters were also consistent with a type II-to-type I MHC phenotype transformation. Importantly, DNV-induced modulation of MHC isoform mRNA transcript levels did not correspond to changes in their cognate proteins, suggesting a major degree of posttranscriptional control. We conclude that DNV hypertrophy of the diaphragm is associated with reciprocal changes in type I and type II MHC isoforms that are directly opposed to the type I-to-type II MHC phenotype transformation reported in the diaphragm DNV atrophy model. Furthermore, in contradistinction to most hypertrophy models, control of MHC gene expression and myofibrillar remodeling after short-term DNV appears to entail major involvement of posttranscriptional regulatory mechanisms.
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Affiliation(s)
- L Yang
- Respiratory Division, McGill University Health Centre, Montreal, Quebec H3A 1A1
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16
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van Lunteren E, Brass EP. Metabolic profiles of cat and rat pharyngeal and diaphragm muscles. RESPIRATION PHYSIOLOGY 1996; 105:171-7. [PMID: 8931176 DOI: 10.1016/0034-5687(96)00043-6] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
Pharyngeal muscles play important roles in the maintenance of upper airway patency during sleep. The present study determined the extent of heterogeneity among pharyngeal muscles and the diaphragm in their metabolic profiles, and examined whether differences among muscles may account for previously described differences in their fatigue resistance. Cat and rat sternohyoid, geniohyoid, genioglossus (cat only) and diaphragm muscle were assayed for activities of the mitochondrial enzyme citrate synthase (CS), the glycolytic enzyme phosphofructokinase (PFK) and the cytosolic enzyme lactate dehydrogenase (LDH). CS activity varied among muscles in both species, being highest for genioglossus in cat and highest for diaphragm in rat. PFK activity was highest for genioglossus in cat, but did not differ among muscles in rat. LDH activity was lower for the genioglossus than the sternohyoid and diaphragm in cat. CS and PFK activities correlated positively, and LDH activity correlated negatively, with in vitro fatigue resistance assessed after 5 min of repetitive stimulation in cat. These data indicate close relationships between metabolic profiles, particularly oxidative capacity, and fatigue resistance of pharyngeal muscles in relationship to each other and to the diaphragm.
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Affiliation(s)
- E van Lunteren
- Department of Medicine, Cleveland VA Medical Center, OH 44106, USA
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van Lunteren E, Vafaie H, Moyer M. Changes in pharyngeal respiratory muscle force produced by K+ channel blockade. RESPIRATION PHYSIOLOGY 1995; 99:331-40. [PMID: 7770668 DOI: 10.1016/0034-5687(94)00112-d] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Abstract
The purpose of the present study was to determine whether the contractility of pharyngeal respiratory muscles can be augmented by altering membranous K+ channel conductance. The effects on twitch force of two K+ channel blockers, tetraethylammonium (TEA, 10 mM) and 4-aminopyridine (4-AP, 0.3 mM), were examined in vitro for sternohyoid and diaphragm muscle strips. Both agents augmented isometric twitch force of both muscles. In response to TEA twitch force of the sternohyoid muscle increased significantly more than that of the diaphragm (by 33 +/- 7 vs. 9 +/- 1%, P = 0.004), whereas with 4-AP the increase in twitch force of the sternohyoid muscle was comparable to that of the diaphragm (55 +/- 15 vs. 64 +/- 6%, P = 0.50). 4-AP shifted the force-frequency relationship of both muscles leftward but did not alter peak tetanic force, so that force with 4-AP exceeded that without drug at stimulation frequencies below 60 Hz. In contrast TEA reduced force at stimulation frequencies > 20 Hz. The isometric contraction times of both muscles was variably prolonged, more so with 4-AP (by 30 +/- 15% for the sternohyoid and 32 +/- 3% for the diaphragm) than with TEA (by 9 +/- 2% for the sternohyoid and 5 +/- 2% for the diaphragm). For the group of muscles and K+ channel blockers, the degree of augmentation of twitch force correlated with the degree of prolongation of contraction time (r = 0.82, P < 0.001), consistent with blocking delayed rectifier K+ channels as the mechanism of increasing muscle force.
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Affiliation(s)
- E van Lunteren
- Department of Medicine, Case Western Reserve University, Cleveland, OH 44106, USA
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18
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Cuppini R, Sartini S, Ambrogini P, Gallo G. Response of fast muscle innervation to hypothyroidism. J Neurol Sci 1994; 127:107-13. [PMID: 7699384 DOI: 10.1016/0022-510x(94)90143-0] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Abstract
The early period of motor innervation development is characterized by multiple innervation of muscle cells. This transitory state in rat extensor digitorum longus (edl) muscle is normally concluded at weaning when a 1:1 ratio between nerve endings and muscle cells is reached. Motor innervation of edl muscle in rats made hypothyroid after weaning was studied in three ways: electrophysiology (intracellular recordings of muscle postsynaptic potentials) was carried out to study neuromuscular transmission; silver impregnation of terminal axons to observe sprouting; force production in twitch and tetanus following direct muscle stimulation and nerve stimulation. A number of multiply innervated muscle cells was found in hypothyroid rats following two months of treatment. This finding seems to be related to the appearance of nodal sprouting in motor axons. No sign of denervated end-plates was found. Twitch and tetanus tension were smaller than in controls, but they were bigger when referred to unitary muscle mass. Time course of twitch, particularly half relaxation, was slowed in muscles of hypothyroid rats. These findings suggest that plastic processes occur in muscle innervation of rats made hypothyroid after weaning. Therefore, thyroid hormones play a role in stabilizing motor innervation not only during development, but also in adults.
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Affiliation(s)
- R Cuppini
- Istituto di Anatomia e Fisiologia, Università di Urbino, Italy
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19
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Grunstein RR, Wilcox I. Sleep-disordered breathing and obesity. BAILLIERE'S CLINICAL ENDOCRINOLOGY AND METABOLISM 1994; 8:601-28. [PMID: 7980349 DOI: 10.1016/s0950-351x(05)80288-5] [Citation(s) in RCA: 23] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Abstract
Recent epidemiological data indicate that obstructive sleep apnoea (OSA) and related conditions are extremely common in the middle-aged population. Obesity is an important aetiological factor in sleep-disordered breathing with a multifactorial role in the pathogenesis of upper airway occlusion. One extreme of the spectrum of sleep-disordered breathing is obesity-hypoventilation syndrome (one type of OSA with awake respiratory failure). Sleep-disordered breathing has a number of clinical consequences, including excess cardiovascular morbidity. Obesity is an important confounder of this association. Treatment of these disorders has been revolutionized by the use of nasal continuous positive airway pressure (CPAP). Weight reduction reduces apnoea severity but is not curative in most obese patients with sleep apnoea.
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Affiliation(s)
- R R Grunstein
- Sleep Disorders Centre, Royal Prince Alfred Hospital, Camperdown, NSW, Australia
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21
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Hendricks JC, Petrof BJ, Panckeri K, Pack AI. Upper airway dilating muscle hyperactivity during non-rapid eye movement sleep in English bulldogs. THE AMERICAN REVIEW OF RESPIRATORY DISEASE 1993; 148:185-94. [PMID: 8317796 DOI: 10.1164/ajrccm/148.1.185] [Citation(s) in RCA: 51] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Abstract
Sleep-disordered breathing (SDB) is seen during rapid eye movement (REM) sleep in English bulldogs, but it is absent during non-REM sleep. The SDB during REM sleep is associated with changes in neural drive to the diaphragm (DIA) and to an upper airway dilator, the sternohyoid (SH). In the present study, the EMG activity of the DIA was recorded in unrestrained, naturally sleeping, English bulldogs (n = 6) and in control dogs (n = 5). The EMG of the SH was recorded in five of these bulldogs and in four of the control dogs. The activity of the DIA was similar in the two groups of dogs throughout sleep, with the normal increased variability and altered recruitment patterns during REM sleep in all dogs. However, in the presence of the narrowed upper airway of bulldogs, the pattern of the upper airway dilator was dramatically different. In bulldogs, SH activity was virtually always related to inspiration (96 to 100% of breaths during both waking and non-REM sleep). In contrast, SH activity showed inspiratory-related increases in only a minority of breaths during non-REM sleep (32%) in control dogs (p < 0.05). Furthermore, SH drive, as measured by the plateau amplitude, fell during REM sleep in bulldogs, whereas it increased in control dogs (p < 0.05). In control dogs without SDB, we found that central respiratory drive to the SH was highest but variable during waking and minimal during non-REM sleep and that it fluctuated with phasic events during REM sleep. In bulldogs, however, high levels of SH activity occurred during waking and throughout non-REM sleep, apparently preventing SDB in these states. Episodic decreases in SH drive were observed during REM, and they were associated with SDB. These data support the proposition that compensatory pharyngeal dilator hyperactivity is necessary to maintain airway patency and normal breathing in bulldogs, a canine breed with an anatomically compromised upper airway.
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Affiliation(s)
- J C Hendricks
- Department of Clinical Studies, School of Veterinary Medicine, Hospital of the University of Pennsylvania, Philadelphia 19104-6010
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22
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Affiliation(s)
- S G McNamara
- David Read Laboratory, Department of Medicine, University of Sydney, Australia
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23
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van Lunteren E. Muscles of the Pharynx: Structural and Contractile Properties. EAR, NOSE & THROAT JOURNAL 1993. [DOI: 10.1177/014556139307200107] [Citation(s) in RCA: 27] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022] Open
Affiliation(s)
- Erik van Lunteren
- Department of Medicine, Division of Pulmonary and Critical Care, Case Western Reserve University, Cleveland, OH 44106
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