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Fiber Density (fiber + density)

Distribution by Scientific Domains

Medical Sciences	64%
Life Sciences	23%

Kinds of Fiber Density

intraepidermal nerve fiber density

nerve fiber density

Selected Abstracts

Morphometric analysis of canine skeletal muscles following experimental callus distraction according to the ilizarov method

JOURNAL OF ORTHOPAEDIC RESEARCH, Issue 4 2000
Bernd Fink
Muscle fiber diameter and fiber-type distribution were analyzed during callus distraction. The right tibia in 24 beagles was lengthened 2.5 cm by callus distraction after osteotomy and application of a ring fixator. Distraction was started at the fifth postoperative day, at a rate of two times for 0.5 mm per day. Twelve dogs that underwent limb-lengthening and three dogs in the control group that did not undergo limb-lengthening were killed at the end of the 25-day distraction phase (group A). The remaining dogs (12 that underwent limb-lengthening and three that did not) were killed after an additional consolidation period of 25 days (group B). The tibialis anterior, extensor digitorum longus, peroneus longus, and gastrocnemius muscles were removed from the right limb (which had undergone distraction) and the left control side of each animal. Crosscut cryostat sections were stained by adenosine triphosphatase at pH 4.3 and 9.4 to determine the size and distribution of types I and II fibers. Morphometric analysis of the muscle fibers was performed by a computer-assisted two-point technique. On the lengthened side, the muscles revealed marked atrophy affecting predominantly type-II fiber in the dogs in group A and affecting both fiber types in dogs in group B. Fiber density increased in both groups. In addition, fiber-type grouping indicative of reinnervation was obvious in group B. Fiber-type distribution in the dogs in group B showed a shift toward type I in the tibialis anterior (p = 0.043) and extensor digitorum longus (p = 0.034) muscles and a shift toward type II in the gastrocnemius (p = 0.038). The data show that tension-stress during tibial lengthening leads to atrophy of type-II fiber, reflecting disuse of muscle fiber in the distraction period as well as neurogenic atrophy followed by the reinnervation processes. Furthermore, the data are consistent with the occurrence of histoneogenesis during limb-lengthening resulting in an increase in fiber density. [source]

Determination of Epidermal Nerve Fiber density.

ACTA NEUROLOGICA SCANDINAVICA, Issue 6 2003
Methodological Issues
First page of article [source]

Near-nerve needle sensory and medial plantar nerve conduction studies in patients with small-fiber sensory neuropathy

EUROPEAN JOURNAL OF NEUROLOGY, Issue 9 2008
K. Uluc
Background and purpose:, The aim of this prospective study was to show and compare the rate of large-fiber involvement with near-nerve needle sensory (NNNS) nerve conduction study (NCS) and with medial plantar NCS recorded with surface electrodes in a group of patients who had clinically pure small-fiber sensory neuropathy (SFSN) with reduced intra-epidermal nerve fiber density in skin biopsy and with normal routine NCS. Methods and results:, The study included 19 patients with clinically pure SFSN with normal routine NCS results and 17 healthy volunteers. Routine NCS, skin biopsy, medial plantar NCS and NNNS NCS were performed. NNNS NCS data were evaluated both by using univariate analysis methods and by using a multivariate analysis method, principal components analysis (PCA). Eight patients (42%) had abnormal results for medial plantar NCS with surface electrodes. Seven patients (37%) had abnormal results for NNNS NCS with PCA, whilst only four patients with univariate analysis. We found a significant correlation between intra-epidermal nerve fiber densities, medial plantar NCS and PCA results of NNNS NCS. Conclusions:, This study showed that large-nerve fibers are also involved in some patients with pure SFSN and medial plantar NCS can accurately diagnose neuropathy without a need for NNNS NCS in patients with normal routine NCS. [source]

Variations in the Thickness and Composition of the Skin of the Giraffe

THE ANATOMICAL RECORD : ADVANCES IN INTEGRATIVE ANATOMY AND EVOLUTIONARY BIOLOGY, Issue 9 2010
Farzana Sathar
Abstract This study examined the skin of two 1- to 2-year-old male giraffes and one adult male, determining skin thickness and histological structure with reference to it functioning as a component of the features required for the maintenance of blood pressure, dermal armor, or thermoregulation. It has been argued that a tight skin surrounding the extremities of the giraffe aids in the movement of fluid against gravity, hence preventing pooling of blood and tissue fluid (edema), but the skin has also been implicated in the thermoregulatory capacities and defensive anatomy of many mammalian species. In one of the younger giraffes, one-half of the skin was analyzed from which close to 170 sites were measured. In the other young and adult giraffes, spot tests to confirm the pattern observed in the fully analyzed individual were undertaken. It was discovered that the skin varied in thickness across the entire body and within regions of the body. Histological evaluation revealed that the skin was mostly collagenous, although interesting patterns of elastic fiber densities were also apparent. The skin in the neck and legs exhibited a morphology that may assist in cardiovascular regulation of blood flow to and from the head and legs, and the skin of the trunk and anterior neck has the possibility of functioning in a protective role. The analyses performed could not add any new data regarding the thermoregulatory role already described for giraffe skin. Anat Rec 293:1615,1627, 2010. © 2010 Wiley-Liss, Inc. [source]

Near-nerve needle sensory and medial plantar nerve conduction studies in patients with small-fiber sensory neuropathy

Deviation of Fiber Tracts in the Vicinity of Brain Lesions: Evaluation by Diffusion Tensor Imaging

ISRAEL JOURNAL OF CHEMISTRY, Issue 1-2 2003
Yaniv Assaf
Diffusion Tensor Imaging (DTI) is used to characterize the diffusion properties of deviated white matter caused by brain tumors. DTI was recently shown to be very helpful in delineating white matter both within brain lesions and surrounding them. Displacement of white matter fibers may be one of the consequences of tumor growth adjacent to white matter. The combination of white matter mapping with DTI and gray matter mapping using functional MRI, in some cases, facilitated assessment of the relation between the shifted cortical areas and the corresponding white matter tracts. We found that the fractional anisotropy extracted from DTI is increased by 38% in areas of non-edematous shifted white matter fibers. By contrast, trace apparent diffusion coefficient (ADC) values in those areas were found to be similar to contralateral side and normal control values. Analysis of the three diffusion tensor eigenvalues revealed that the increase in the fractional anisotropy is a result of two processes. The first is the increase in the diffusion parallel to the fibers,,1 (by 18%), and the second is the decrease in the diffusion perpendicular to fibers,,3 (by 34%) as compared with the contralateral side. These opposing changes cause an increase in the diffusion anisotropy but no change in the trace ADC. It is suggested that the pressure caused by the tumor may lead to an increase in white matter fiber tension, thus causing an increase in ,1. On the other hand, the same pressure causes increased fiber density per unit area, leading to a higher degree of restricted diffusion in the extracellular space and, hence, a reduction in ,3. [source]

Dermal sheet preparations in the evaluation of dermal innervation in Parkinson's disease and multiple system atrophy

JOURNAL OF CUTANEOUS PATHOLOGY, Issue 3 2009
Peter Novak
Background:, Evaluation of dermal nerve fibers in conventional vertical sections is difficult because of the small number of fibers available for examination. In this study, we evaluated dermal sheet mounts for fibers in which the majority of fibers can be visualized. Methods:, We compared the dermal small fiber density in six Parkinson's disease (PD) and six multiple system atrophy (MSA) patients using dermal sheet preparations (DSP). DSP are based on epidermal-dermal separations and immunostaining of the entire dermis by the nerve growth factor receptor p75 antibody that stains both autonomic and sensory fibers. Results:, The small fiber density was reduced in PD compared with MSA (p < 0.0001), suggesting the presence of small fiber neuropathy in PD. Conclusions:, DSP offer a unique method of evaluation of dermal nerve fibers. This method can be used to evaluate small nerve fibers in many neurological disorders such as MSA and PD. [source]

Morphometric analysis of canine skeletal muscles following experimental callus distraction according to the ilizarov method

Effects of Oxidation Curing and Sintering Additives on the Formation of Polymer-Derived Near-Stoichiometric Silicon Carbide Fibers

JOURNAL OF THE AMERICAN CERAMIC SOCIETY, Issue 2 2008
Lifu Chen
The effects of oxygen pick-up and sintering additives on the formation of silicon carbide (SiC) fibers from polyaluminocarbosilane are studied. It has been found that the strict control of oxygen pick up during the oxidation curing is essential to produce near-stoichiometric SiC fibers. When the molar ratio of oxygen to excess carbon in the pyrolyzed fibers (SiCxOy) is slightly over 1 (O/CExcess=y/(x,1)>1), the excess carbon is eliminated during the subsequent sintering as CO and CO2 as a result of the decomposition of SiCxOy; the remaining oxygen is removed as SiO and CO vapor, leaving near-stoichiometric SiC as the residue. However, with still increasing oxygen pick up, the final ceramic fibers become more porous and rich in silicon. The evolution of CO, CO2, and SiO generates high porosity in the absence of a sintering additive, leading to low fiber density. The inter-connected and open porosity favors the formation of CO. In contrast, for the fibers containing aluminum (Al) or Al/B sintering additives, the pores are much smaller and essentially closed, favoring the formation of CO2. Therefore, after sintering at 1800°C, the fibers without sintering additives contain excess silicon, while those with sintering additives are near stoichiometric. Al is beneficial to the densification but it alone cannot produce fibers of high density. When B is added in addition to Al, the fibers can be sintered to nearly full density. [source]

Myelin thickenings in val 102/fs null mutation of MPZ gene

JOURNAL OF THE PERIPHERAL NERVOUS SYSTEM, Issue 2 2004
MV De Angelis
Myelin thickenings, abnormal myelin foldings and tomacula have been rarely described in CMT1B. In two unrelated patients of different age (patient 1: 29 years old; patient 2: 65 years old) with CMT1B and Val 102/fs null mutation of MPZ gene we performed morphometric analysis, teased fibers and ultrastructural examination of sural nerve. We found: 1) markedly decreased fiber density with prevalent loss of large diameter fibers (patient 1: 4419 fibers/mm2; patient 2: 1326 fibers/mm2); 2) evidence of de-remyelination; and 3) paranodal and internodal myelin thickenings in virtually all fibers. Patient 1 has myelin thickenings measuring more than 50% of the fiber diameter in 14% of fibers and thickenings greater than 30% in 33% of fibers. Patients 2 presents myelin thickenings measuring more than 50% of fiber diameter in 23% of fibers and thickening greater than 30% in 49% of fibers. When considering the absolute measure of myelin thickenings and their number over 100 internodes, patient 1 presents 150 small myelin thickenings (<8 mm of diameter) whereas patient 2 has 57. The number of globules (8,12 mm of diameter) is 56 in patient 1 and 45 in patient 2. The number of myelin thickenings greater than 12 mm is 33 in patient 1 and 45 in patient 2. Ultrathin sections showed myelin infoldings, outfoldings and uncompacted myelin. CMT1B with a heterozygous null mutation of MPZ gene is characterized by abundant focal myelin thickenings. Similar findings have been described in the P0 deficient heterozygous mice. [source]

Abstracts of the 8th Meeting of the Italian Peripheral Nerve Study Group: 79

JOURNAL OF THE PERIPHERAL NERVOUS SYSTEM, Issue 1 2003
U Del Carro
Peripheral neuropathy is one of the most common secondary complications of diabetes mellitus, causing severe and prolonged morbidity. However, clinical and experimental studies have reported that careful glucose control may prevent, stabilize, and/or reverse neuropathy and other chronic diabetic complications. Unfortunately, insulin therapy does not prevent the development or progression of chronic lesions in the vessels, kidneys, eyes, or nerves of the diabetic patient. There is great interest in investigating other forms of endocrine replacement therapy, such as transplantation of the pancreas or of the islets of Langerhans (IT). Diabetic polyneuropathy (DP) evolution is characterized by progressive demyelination and axonal loss and is manifested by signs and symptoms on physical examination and abnormalities in nerve conduction studies (NCS). NCS provide reliable, noninvasive, objective measures of peripheral nerve function and constitute the most important technique for the evaluation of the severity of DP in clinical trials. Several research groups have demonstrated that skin biopsy with measurement of intraepidermal nerve fiber density is another method minimally invasive and repeatable that provides direct pathologic evidence of axonal damage in diabetic neuropathy. Fifty-one consecutive IDDM patients with or without end stage renal disease were enrolled at the moment of islet (Is), kidney (KD), kidney-pancreas (KP) or kidney-islet (KI) transplantation. Patients underwent skin biopsy punch, neurologic examination and neurophysiological investigation. Particularly, 20 pts underwent KP tx, 16 KD tx, 10 islet tx and 5 KI. The patients were comparable for duration of diabetes, dialysis (when present), age, lipid profile. In half of the patients a follow-up of 2 years has been reached. After KP tx, and partially with KI, a complete normalization of glycometabolic control has been achieved, with statistically lower HbA1c in comparison with KD group (KP = 6.2; 0.1% vs. KD = 8.4; 0.5%; p < 0.01). In the KI/Is group, a long-term restoration of islet endocrine function has been achieved, with insulin independence. When this has been lost, a persistent secretion of C-peptide was shown for a long period of time. This was correlated with a global improvement quality of life and vascular structure. Preliminary results will be presented. [source]

Conventional DTI vs. slow and fast diffusion tensors in cat visual cortex

MAGNETIC RESONANCE IN MEDICINE, Issue 5 2003
Itamar Ronen
Abstract Diffusion tensor imaging (DTI) uses water diffusion anisotropy in axonal fibers to provide a tool for analyzing and tracking those fibers in brain white matter. In the present work, multidirectional diffusion MRI data were collected from a cat brain and decomposed into slow and fast diffusion tensors and directly compared with conventional DTI data from the same imaging slice. The fractional anisotropy of the slow diffusing component (Dslow) was significantly higher than the anisotropy measured by conventional DTI while reflecting a similar directionality and appeared to account for most of the anisotropy observed in gray matter, where the fiber density is notoriously low. Preliminary results of fiber tracking based on the slow diffusion component are shown. Fibers generated based on the slow diffusion component appear to follow the vertical fibers in gray matter. DslowTI may provide a way for increasing the sensitivity to anisotropic structures in cortical gray matter. Magn Reson Med 49:785,790, 2003. © 2003 Wiley-Liss, Inc. [source]

Intraepidermal nerve fiber density as a marker of early diabetic neuropathy

MUSCLE AND NERVE, Issue 5 2007
T. Umapathi MB
Abstract The purpose of the study was to reliably identify an early stage of diabetic polyneuropathy (DPN) by measuring injury to epidermal nerve fibers. We compared intraepidermal nerve fiber density (IENFD) at the ankle and thigh of 29 diabetic subjects who had no clinical or electrophysiological evidence of small- or large-fiber neuropathy to that of 84 healthy controls. The mean ankle IENFD of diabetic subjects was 9.1 ± 5.0 mm and that of controls, 13.0 ± 4.8 mm (P < 0.001). The thigh IENFD did not differ significantly. The IENFD ratio (thigh IENFD divided by ankle IENFD) was 2.39 ± 1.30 in diabetic subjects and 1.77 ± 0.58 in controls (P < 0.001), indicating a length-dependent reduction of IENFD in diabetics. Ankle IENFD remained significantly lower and the IENFD ratio higher in diabetic subjects after adjusting for age. Two subjects had parasympathetic dysfunction, two had retinopathy, and two early nephropathy. Age, height, weight, duration of diabetes, and average HbA1c did not influence IENFD among diabetic subjects. We used receiver operating characteristic (ROC) curves to describe and compare the utility of various threshold values of ankle IENFD and IENFD ratio for the diagnosis of early DPN. The sensitivity and specificity of diagnosing DPN using ankle IENFD of less than 10 mm were 72.4% and 76.2%, respectively. Thus, asymptomatic diabetics have a measurable, length-dependent reduction of distal epidermal nerves. Analogous to microalbuminuria in diabetic nephropathy, reliable identification and quantitation of nascent diabetic neuropathy may have potential therapeutic implications. Muscle Nerve, 2007 [source]

Treatment-induced diabetic neuropathy: A reversible painful autonomic neuropathy

ANNALS OF NEUROLOGY, Issue 4 2010
Christopher H. Gibbons MD
Objective To describe the natural history, clinical, neurophysiological, and histological features, and outcomes of diabetic patients presenting with acute painful neuropathy associated with glycemic control, also referred to as insulin neuritis. Methods Sixteen subjects presenting with acute painful neuropathy had neurological and retinal examinations, laboratory studies, autonomic testing, and pain assessments over 18 months. Eight subjects had skin biopsies for evaluation of intraepidermal nerve fiber density. Results All subjects developed severe pain within 8 weeks of intensive glucose control. There was a high prevalence of autonomic cardiovascular, gastrointestinal, genitourinary, and sudomotor symptoms in all subjects. Orthostatic hypotension and parasympathetic dysfunction were seen in 69% of subjects. Retinopathy worsened in all subjects. Reduced intraepidermal nerve fiber density (IENFD) was seen in all tested subjects. After 18 months of glycemic control, there were substantial improvements in pain, autonomic symptoms, autonomic test results, and IENFD. Greater improvements were seen after 18 months in type 1 versus type 2 diabetic subjects in autonomic symptoms (cardiovascular p < 0.01; gastrointestinal p < 0.01; genitourinary p < 0.01) and autonomic function tests (p < 0.01, sympathetic and parasympathetic function tests). Interpretation Treatment-induced neuropathy is characterized by acute, severe pain, peripheral nerve degeneration, and autonomic dysfunction after intensive glycemic control. The neuropathy occurred in parallel with worsening diabetic retinopathy, suggesting a common underlying pathophysiological mechanism. Clinical features and objective measures of small myelinated and unmyelinated nerve fibers can improve in these diabetic patients despite a prolonged history of poor glucose control, with greater improvement seen in patients with type 1 diabetes. ANN NEUROL 2010;67:534,541 [source]

Controlled release of neurotrophin-3 from fibrin-based tissue engineering scaffolds enhances neural fiber sprouting following subacute spinal cord injury,

BIOTECHNOLOGY & BIOENGINEERING, Issue 6 2009
Philip J. Johnson
Abstract This study investigated whether delayed treatment of spinal cord injury with controlled release of neurotrophin-3 (NT-3) from fibrin scaffolds can stimulate enhanced neural fiber sprouting. Long Evans rats received a T9 dorsal hemisection spinal cord injury. Two weeks later, the injury site was re-exposed, and either a fibrin scaffold alone, a fibrin scaffold containing a heparin-based delivery system with different concentrations of NT-3 (500 and 1,000,ng/mL), or a fibrin scaffold containing 1,000,ng/mL of NT-3 (no delivery system) was implanted into the injury site. The injured spinal cords were evaluated for morphological differences using markers for neurons, astrocytes, and chondroitin sulfate proteoglycans 2 weeks after treatment. The addition of 500,ng/mL of NT-3 with the delivery system resulted in an increase in neural fiber density compared to fibrin alone. These results demonstrate that the controlled release of NT-3 from fibrin scaffolds can enhance neural fiber sprouting even when treatment is delayed 2 weeks following injury. Biotechnol. Bioeng. 2009; 104: 1207,1214. © 2009 Wiley Periodicals, Inc. [source]

Sural nerve biopsy may predict future nerve dysfunction

ACTA NEUROLOGICA SCANDINAVICA, Issue 1 2009
S. Thrainsdottir
Objective,,, Sural nerve pathology in peripheral neuropathy shows correlation with clinical findings and neurophysiological tests. The aim was to investigate progression of nerve dysfunction over time in relation to a baseline nerve biopsy. Methods,,, Baseline myelinated nerve fiber density (MNFD) was assessed in sural nerve biopsies from 10 men with type 2 diabetes, 10 with impaired and 10 with normal glucose tolerance. Nerve conduction and quantitative perception thresholds were estimated at baseline and follow-up (7,10 years later). Results,,, Subjects with low MNFD (,,4700 fibers/mm2) showed decline of peroneal amplitude (P < 0.02) and conduction velocity (P < 0.04), as well as median nerve sensory amplitude (P < 0.05) and motor conduction velocity (P < 0.04) from baseline to follow-up. In linear regression analyses, diabetes influenced decline of nerve conduction. MNFD correlated negatively with body mass index (r = ,0.469; P < 0.02). Conclusion,,, Low MNFD may predict progression of neurophysiological dysfunction and links obesity to myelinated nerve fiber loss. [source]