Differences in Fibre Type Composition Between Human Masseter and Biceps Muscles in Young and Adults Reveal Unique Masseter Fibre Type Growth Pattern

The human jaw system is different from those of other primates, carnivores, ruminants, and rodents in temporomandibular joint and muscle anatomy. In adults, jaw muscles also differ markedly from limb and trunk muscles in composition and distribution of fibre types. It can be assumed that age‐related changes between young age to adulthood in terms of craniofacial growth, teeth eruption, and improvement of jaw functions are paralleled by alterations also in composition and distribution of jaw muscle fibre types. To address this question, we have examined the fibre type composition of the human masseter, a jaw closing muscle, at young age. For comparison, the young biceps brachii was examined. The results were compared with previous data for adult masseter and biceps muscles. Young masseter and biceps were similar in that type I fibres outnumbered other fibre types and were of the same diameter. However, they differed in composition of other fibre types. Young masseter contained fibre types I, IM, IIC, IIAB, IIB, and scarce IIA, with regional differences, whereas young biceps showed types I, IIA, IIAB, and few IIB. Young masseter differed from young biceps also by smaller type II fibre diameter and by containing fetal MyHC. In addition, the masseter and biceps differed in age‐related changes of composition and distribution of fibre types between young age and adulthood. We conclude that the human masseter is specialized in fibre types already at young age and shows a unique fibre type growth pattern, in concordance with being a separate allotype of muscle. Anat Rec, 2011. © 2011 Wiley‐Liss, Inc.     

Abnormal Peripapillary Nerve Fibre Layer Thickness Demonstrated by Optical Coherence Tomography in Cases of Optic Atrophy: Is There a Correlation With Aetiology?

Optical coherence tomography of the peripapillary nerve fibre layer has been used in optic atrophy for identification of axonal loss and for differential diagnosis. In the present study, we aim to evaluate whether the pattern of peripapillary nerve fibre layer thinning, based on the optical coherence tomography normative database, correlates with aetiology in cases of optic atrophy. This retrospective study is approved by the Tan Tock Seng Hospital Ethics Review Board. Consecutive patients with optic atrophy seen in the Neuro-Ophthalmology Clinic between May 2005 and August 2006 were included. The normal eyes of the patients served as controls. All patients underwent imaging using Stratus optical coherence tomography of the peripapillary nerve fibre layer, optic disc photographs and Humphrey perimetry. The aetiology of each case of optic atrophy were made by means other than the optical coherence tomography. Significant nerve fibre layer thinning was defined as a reading in the red quadrant on the Stratus optical coherence tomography printout, which indicates the 1% percentile of the Stratus optical coherence tomography normative database. Twenty-nine patients (39 eyes) with optic atrophy were included in the study. The cases included non-arteritic anterior ischaemic optic neuropathy (14 eyes), compressive optic neuropathy (10 eyes), toxic optic neuropathy, traumatic optic neuropathy, previous optic neuritis, inflammatory optic neuropathy, and central retinal artery occlusion. Cases with isolated superior quadrant thinning were three times more likely to be non-arteritic anterior ischaemic optic neuropathy (odds ratio 4.07; 95% confidence interval: 0.8–20.75), although this was not statistically significant (p?=?0.079). Patients with isolated superior peripapillary nerve fibre layer thinning on the Stratus optical coherence tomography are more likely to be non-arteritic anterior ischaemic optic neuropathy patients. The other aetiologies did not show any specific pattern of thinning.     

Novel TPM3 mutation in a family with cap myopathy and review of the literature

Cap myopathy is a rare congenital myopathy characterized by the presence of caps within muscle fibres and caused by mutations in ACTA1, TPM2 or TPM3. Thus far, only three cases with TPM3-related cap myopathy have been described. Here, we report on the first autosomal dominant family with cap myopathy in three-generations, caused by a novel heterozygous mutation in the alpha-tropomyosin-slow-encoding gene (TPM3; exon 4; c.445C>A; p.Leu149Ile). The three patients experienced first symptoms of muscle weakness in childhood and followed a slowly progressive course. They presented generalized hypotrophy and mild muscle weakness, elongated face, high arched palate, micrognathia, scoliosis and respiratory involvement. Intrafamilial variability of skeletal deformities, respiratory involvement and mild cardiac abnormalities was noted. Muscle MRI revealed a recognizable pattern of fatty muscle infiltration and masseter muscle hypertrophy. Subsarcolemmal caps were present in 6–10% of the fibres and immunoreactive with anti-tropomyosin antibodies. We conclude that the MRI-pattern of muscle involvement and the presence of masseter muscle hypertrophy in cap myopathy may guide molecular genetic diagnosis towards a mutation in TPM3. Regular respiratory examinations are important, even if patients have no anamnestic clues. We compare our findings to all cases of cap myopathy with identified mutations (n = 11), thus far reported in the literature.     

RYR1-related congenital myopathy with fatigable weakness,responding to pyridostigimine

The spectrum of RYR1 mutation associated disease encompasses congenital myopathies, exercise induced rhabdomyolysis, malignant hyperthermia susceptibility and King-Denborough syndrome. We report the clinical phenotype of two siblings who presented in infancy with hypotonia and striking fatigable ptosis. Their response to pyridostigimine was striking, but genetic screening for congenital myasthenic syndromes was negative, prompting further evaluation. Muscle MRI was abnormal with a selective pattern of involvement evocative of RYR1-related myopathy. This directed sequencing of the RYR1 gene, which revealed two heterozygous c.6721C>T (p.Arg2241X) nonsense mutations and novel c.8888T>C (p.Leu2963Pro) mutations in both siblings. These cases broaden the RYR1-related disease spectrum to include a myasthenic-like phenotype, including partial response to pyridostigimine. RYR1-related myopathy should be considered in the presence of fatigable weakness especially if muscle imaging demonstrates structural abnormalities. Single fibre electromyography can also be helpful in cases like this.     

Antioxidant and Physicochemical Properties of Hydrogen Peroxide‐Treated Sugar Beet Dietary Fibre

The aim of the present work was to examine if hydrogen peroxide treatment of sugar beet fibre that aimed at improving its physicochemical properties would impair its antioxidant potential. Three different sugar beet fibres were obtained from sugar beet – non‐treated fibre (NTF) from sugar beet cossettes extracted with sulphurous acid, treated fibre (TF) from NTF treated with hydrogen peroxide in alkaline solution and commercially available Fibrex^®. The antioxidant activity of extractable and non‐extractable fibre fractions in ethanol/water mixture (80:20, v/v) of three fibre samples was estimated. Non‐extractable fractions obtained after alkaline treatment of investigated fibres were much higher in phenolic compounds and possessed higher antioxidant potential than extractable fractions. Ferulic acid was proven to be the dominant phenolic acid. Regarding both extractable and non‐extractable fractions, Fibrex^® had the highest antioxidant activity in chemical tests, while NTF was superior in comparison with TF. Based on the results of Caco‐2 cells‐based test, all non‐extractable fractions possessed potential for reactive oxygen species inhibition. Regarding the extractable fractions, only the TF manifested this effect.Copyright © 2016 John Wiley & Sons, Ltd.     

High wholegrain barley β-glucan lowers food intake but does not alter small intestinal macronutrient digestibility in ileorectostomised rats

Using barley cultivars differing widely in β-glucan content, we aimed to determine their effects on small intestinal macronutrient digestion in 24 ileorectostomised rats. The rats were fed 1 of 4 experimental diets, each containing a different barley variety, for 11 d. The diets had a content of 0, 2.1, 2.6 and 4.3?g of β-glucan/100?g. Feed intake and faecal excretion of fat, protein, starch, and non-starch polysaccharides were determined in the final 5 d of the study and apparent macronutrient digestibility calculated. Higher dietary levels of β-glucan (2.6% and 4.3%) lowered feed intake (by 15 and 19%, respectively) but final body weight was only lowered by the 4.3% β-glucan diet relative to rats fed the 0% β-glucan diet (all ps?相似文献   

Potential fat-lowering and prebiotic effects of enzymatically treated okara in high-cholesterol-fed Wistar rats

This study evaluates the effect of the lipid profile on serum, liver and faeces, and the potential prebiotic effect of diets supplemented with enzymatically treated okara (okara^ET) in high-cholesterol fed Wistar rats. Triglyceride levels were significantly reduced in the serum (p?p?ET treated rats. Total lipids, triglycerides and bile acids were significantly higher (p?ET diet. The pH of faecal contents from treated okara^ET rats was lower (p?p?ET, therefore, reduced triglycerides in serum and liver, and increased the excretion of total lipids, triglycerides and bile acids, improving the lipid profile in rats fed with high-cholesterol diets. Okara^ET fibre can improve intestinal transit by increasing faecal bulk. The decreased pH and increased SCFA production indicated that okara^ET fibre fermentation occurred, suggesting a potential prebiotic effect.     

Development and inhibition of the target phenomenon in tenotomized rat muscle

Summary The sequence of development of the target phenomenon in tenotomized gastrocnemius muscle was studied: the presence of target fibres was preceded by the occurrence of contraction bands and of moth eaten appearance of the fibres. This phenomenon was far more pronounced and occurred earlier in type II than in type I fibres.This target phenomenon and the contraction artefacts could be inhibited in the tenotomized muscles by simultaneous neurotomy or immobilization of the muscle with a plaster cast. Delayed denervation inhibited also the target phenomenon, if performed less than 5 days after the tenotomy. These series of experiments seem to indicate that the target phenomenon occurs in more irritable muscle fibres and that muscular activity is needed for its development.     

Intra- and intermuscular variation in human quadriceps femoris architecture assessed in vivo

Despite the functional importance of the human quadriceps femoris in movements such as running, jumping, lifting and climbing, and the known effects of muscle architecture on muscle function, no research has fully described the complex architecture of this muscle group. We used ultrasound imaging techniques to measure muscle thickness, fascicle angle and fascicle length at multiple regions of the four quadriceps muscles in vivo in 31 recreationally active, but non-strength-trained adult men and women. Our analyses revealed a reasonable similarity in the superficial quadriceps muscles, which is suggestive of functional similarity (at least during the uni-joint knee extension task) given that they act via a common tendon. The deep vastus intermedius (VI) is architecturally dissimilar and therefore probably serves a different function(s). Architecture varies significantly along the length of the superficial muscles, which has implications for the accuracy of models that assume a constant intramuscular architecture. It might also have consequences for the efficiency of intra- and intermuscular force transmission. Our results provide some evidence that subjects with a given architecture of one superficial muscle, relative to the rest of the subject sample, also have a similar architecture in other superficial muscles. However, this is not necessarily true for vastus lateralis (VL), and was not the case for VI. Therefore, the relative architecture of one muscle cannot confidently be used to estimate the relative architecture of another. To confirm this, we calculated a value of whole quadriceps architecture by four different methods. Regardless of the method used, we found that the absolute or relative architecture of one muscle could not be used as an indicator of whole quadriceps architecture, although vastus medialis, possibly in concert with VL and the anterior portion of VI, could be used to provide a useful snapshot. Importantly, our estimates of whole quadriceps architecture show a gender difference in whole quadriceps muscle thickness, and that muscle thickness is positively correlated with fascicle angle whereas fascicle length is negatively, although weakly, correlated with fascicle angle. These results are supportive of the validity of estimates of whole quadriceps architecture. These data are interpreted with respect to their implications for neural control strategies, region-specific adaptations in muscle size in response to training, and gender-dependent differences in the response to exercise training.