Search PubMed⌕ Search

SEARCH · Search PubMed

Results for “fiber”

Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 433 records · Page 24Linked to original sources
PubMed1988

Fiber type, fiber size, and capillary geometric features of the semitendinosus muscle in three types of dogs.

The fiber type, fiber size, and capillary geometric features were determined from the center of the proximal half of the left and right semitendinosus muscles in 5 mixed-breed dogs, 5 hound-type dogs, and 5 Beagles. There were no significant differences between the left and right muscles of each dog. Comparisons among the 3 groups of dogs revealed that the hound-type dogs had the largest fibers (type I and type II); however, the 3 groups were similar in their fiber-type percentages and their capillary geometric features.

Animals↗
PubMed1978

[Polarized ultraviolet fluorescence microscopic study of the structural changes in muscle fiber contractile proteins. V. The possible nature of the conformational rearrangements in heavy meromyosin in fiber relaxation].

The mode and degree of tryptophanyl orientation relative to muscle fiber axes within hydrophobic and hydrophylic sites of myosin macromolecule in the presence of a fluorescence quencher (acrylamide, NO-3) during rigor and relaxation of glycerinated muscle fibers were studied using the polarized ultraviolet fluorescent microscopy. It was shown that myosin tryptophanyls both in LMM and HMM are oriented with their short axes along the longer axis of muscle fiber. Tryptophanyls in LMM have a more pronounced anisotropy of orientation in comparison with the fluorophore orientation anisotropy in hydrophobic sites of HMM. During the muscle fiber relaxation, conformational changes in HMM take place owing to which a section of polypeptide chain with a hydrophilic fluorophore is probably submerged deep into the macromolecule and becomes unapprochable to the quencher.

Animals↗
PubMed1985

Aortic endothelial cell during regeneration. Remodeling of cell junctions, stress fibers, and stress fiber-membrane attachment domains.

We have studied in regenerating endothelium of rat thoracic aortas (a) organization of tight and gap junctions by means of morphometry using freeze-fracture electron microscopy, (b) development of cytoplasmic actin microfilament bundles (stress fibers) by means of morphometry using thin section electron microscopy, and (c) distribution of filipin-sterol complexes in the endothelial plasma membrane using thin section and freeze-fracture electron microscopy. The index of complexity for tight junctions and the index expressing the average width of gap junctions were significantly higher in regenerating endothelium than in normal aortic endothelium. In regenerating endothelium, there was a significant increase of the stress fiber to endothelial volume density ratio as compared to normal. Stress fibers were connected to cytoplasmic microfilament condensations located at the abluminal plasma membrane; the surface density of these condensations was significantly increased in regenerating endothelium as compared to normal. Filipin-cholesterol complexes were few or absent at stress fiber-membrane attachment sites but numerous in the remaining endothelial plasma membrane. This morphologic remodeling of the aortic endothelial cell layer may help to explain changes of endothelial cell function occurring in situations associated with increased cell turnover and motion.

Animals↗
PubMedDate not supplied

Histomorphometric study on the osteocyte lacuno-canalicular network in animals of different species. I. Woven-fibered and parallel-fibered bones.

A comparative histomorphometric study was carried out on the extension of lacunocanalicular network in two types of bone tissue (woven and parallel-fibered) in shaft bones of various animals (Frog, Chicken, Rabbit, Bovine, Horse, Dog, Man), with the aim to understand whether the distribution of osteocyte network is related to the organization of the collagen fibers or to the animal species. By means of a light microscope (LM) connected with an image-Analyser the following parameters were measured: 1) the cross-sectional area and the volume of osteocyte lacunae; 2) the osteocyte density; 3) the number of canaliculi departing both from the whole outline of the sectional area of osteocyte lacunae and, in the parallel-fibered osteons only (both with LM and SEM), from their two opposite walls, i.e., from the wall facing the Haversian canal (vascular wall) and from that facing the cement line (peripheral wall). In all the animals studied the size and density of osteocyte lacunae as well as the extension of the canalicular network proved to be markedly higher in woven than in parallel-fibered bone, whereas no relation with the species was found. These findings suggest that the function of osteocyte is mainly involved in the regulation of skeletal homeostasis, as discussed in the present paper.

Animals↗
PubMed1989

[Selective electric-current inhibition of signals from the C fibers in nerve fiber microbundles: a method for identifying A and C afferents].

Direct electric current of 3 microA applied through platinum electrode during 10 s to a fine strand teased mechanically from saphenous nerve, inhibits selectively C-fibre spikes in the strand and does not inhibit A-fiber spikes. The selective inhibition of C-fibers spikes in a fine strand is proposed as a method to identify a type of a single nerve fiber.

Afferent Pathways↗
PubMedDate not supplied

Congenital myopathy with uniform type 1 fiber predominance and type 2 fiber hypoplasia: report of one case.

A 2-month-old female infant, presented with frequent choking and cyanosis during feeding, and poor sucking capability since the age of 45 days. Growth retardation with body weight and length below the third percentile, and head girth below the tenth percentile, were noted on admission. Generalized hypotonia, mild proximal muscle weakness and diminished tendon reflex were also noted. A biopsy from the left quadriceps femoralis showed uniform type 1 fiber (90%) predominance, and a decrease in fiber size and number of type 2 fibers. A biopsy from her father revealed uniform type 1 predominance (99.8%) and 30% central nuclei change. The course of her illness was rather short, and the patient has developed normally since the age of 4 months. Significant improvement in muscle strength and normal intelligence were observed after 3 years of clinical follow-up.

Female↗
PubMed2001

Nerve fibers innervating the cranial and spinal meninges: morphology of nerve fiber terminals and their structural integration.

Pachymeninx and leptomeninx of cranial cavity and spine are considerably different in their collagenous fiber texture, cellular composition, vascularization, and innervation. The majority of meningeal nerve fibers terminate as free nerve endings whereas encapsulated and lamellated nerve terminals additionally occur in higher vertebrates including man. With respect to nerve fiber classification, arborization pattern, topography, and organization of the microenvironment at the termination site afferent and efferent nerve terminals are differentiated. Only the dura mater and the pial subcompartment of the leptomeninx possess the morphological prerequisites for neurogenic inflammation. In the current review, the results of morphological studies regarding the meningeal innervation including the sites of CSF (cerebrospinal fluid) production and absorption are discussed with emphasis on their structure-function relationships.

Arachnoid↗
PubMed2005

A quantitative method for the assessment of intraepidermal nerve fibers in small-fiber neuropathy.

OBJECTIVES: The purpose of this paper is to present an easy-to-use and reproducible morphometrical method of determining the density of intraepidermal nerve fibers (IENF) per epidermal area with the corresponding reference range of the IENF-counts. METHODS: Thirty patients and 22 controls were included in this study. The patients were divided into three groups: small-fiber (SFN), diabetic and demyelinating neuropathy. All subjects underwent punch skin biopsy. Specimens were fixed routinely in formalin and thereafter embedded in paraffin. Nerve fibers were revealed using immunoperoxidase staining with panaxonal antibody PGP 9.5. Using light microscopy, immunopositive nerves were counted morphometrically per epidermal area (NPEA) and, for comparison, per epidermal length (NPEL). RESULTS: Both the NPEA and NPEL estimates of SFN and diabetic neuropathy group differed significantly from those of control specimen (p < 0.001 and p < 0.001, Mann-Whitney test). Our method of counting, NPEA, shows a good correlation to NPEL (r = 0.945). CONCLUSIONS: IENF-counting by a new morphometric modification is reproducible and diagnostically sensitive and can easily be adopted in any laboratory familiar with the basic immunohistochemical methodology. The method is less dependent on costly technical support systems and seems to be less time consuming when compared with conventional methods for IENF-counting.

Biopsy, Needle↗
PubMed1987

Coupling between unmyelinated peripheral nerve fibers does not involve sympathetic efferent fibers.

Bidirectional coupling of action potential activity between unmyelinated fibers in the normal peripheral nerve of monkey has recently been reported. Often typical C-fiber nociceptors are identified with the coupled fibers. In this study, sympathetic stimulation and sympathetic ablation experiments demonstrated that the sympathetic nervous system is not involved in this coupling.

Action Potentials↗
PubMed1979

Nerve fiber conduction-velocity distributions. I. Estimation based on the single-fiber and compound action potentials.

A method is described for estimating the distribution of nerve-fiber conduction velocities in a nerve bundle. This method is based on a detailed general model of the nerve bundle compound action potential, which is characterized as a weighted sum of delayed single-fiber action potentials. The non-iterative estimation method is applied to two examples taken from existing literature, demonstrating the similarity of conduction velocity and fiber diameter distributions, sensitivity of the estimate to variations in important model parameters, and applicability to the differentiation of normal and abnormal nerve function.

Action Potentials↗
PubMed1981

Mossy fiber and Purkinje cell axon collateral arborization patterns in normal and X-irradiated rat cerebellum: a light microscopic study using horseradish peroxidase fiber filling techniques.

The horseradish peroxidase neuronal staining technique was applied to reveal through anterograde and retrograde staining the detailed morphology of fiber arborization patterns in the cerebella of normal adult rats as well as those treated with neonatal X-irradiation. Morphological features of anterogradely-filled mossy fibers including the axonal arborization and glomerular-type synaptic specializations were found to be similar in all groups studied. In addition, retrogradely-filled Purkinje cell axon collaterals in the cerebella degranulated by X-irradiation exhibited much more elaborate branching and arborization of recurrent collaterals than those labeled in the normal cerebellar cortex. The presence of glomerular-type specializations in the degranulated cerebellum suggested that mossy fibers develop and maintain their normal features independent of major influences from granule cells. The hypertrophy observed after destruction of the cerebellar interneurons suggests the hypothesis that the growth of the normal Purkinje cell collateral system is normally suppressed by extrinsic factors within the neuronal circuit.

Animals↗
PubMed1990

Transplantation of embryonic olive in the climbing-fiber-deprived adult rat cerebellum: synaptogenesis on host Purkinje dendritic spines by donor climbing fibers.

Synaptic formation by donor climbing fibers on the host Purkinje spines was observed in our experiments. In the adult rat cerebellum where the inferior olive and climbing fibers had been destroyed by intraperitoneal injection of 3-acetylpyridine, the medullary embryonic 14-16-day (E14-E16) tissue containing the olive was grafted. After 3 weeks, climbing-fiber-type preterminals bearing closely-packed round vesicles were found that established synaptic contacts on dendritic spines of the host Purkinje cells. Quantitative analysis indicates the increment of newly-formed climbing presynaptic terminals, the number of which was statistically significant (P less than 0.01).

Afferent Pathways↗
PubMed2004

Bidirectional parallel fiber plasticity in the cerebellum under climbing fiber control.

Cerebellar parallel fiber (PF)-Purkinje cell (PC) synapses can undergo postsynaptically expressed long-term depression (LTD) or long-term potentiation (LTP) depending on whether or not the climbing fiber (CF) input is coactivated during tetanization. Here, we show that modifications of the postsynaptic calcium load using the calcium chelator BAPTA or photolytic calcium uncaging result in a reversal of the expected polarity of synaptic gain change. At higher concentrations, BAPTA blocks PF-LTP. These data indicate that PF-LTD requires a higher calcium threshold amplitude than PF-LTP induction and suggest that CF activity acts as a polarity switch by providing dendritic calcium transients. Moreover, previous CF-LTD induction changes the relative PF-LTD versus -LTP induction probability. These findings suggest that bidirectional cerebellar learning is governed by a calcium threshold rule operating "inverse" to the mechanism previously described at other glutamatergic synapses (BCM rule) and that the LTD/LTP induction probability is under heterosynaptic climbing fiber control.

Animals↗
PubMed2003

Alterations in retinal nerve fiber layer thickness following indirect traumatic optic neuropathy detected by nerve fiber analyzer, GDx-N.

PURPOSE: To evaluate changes in the retinal nerve fiber layer following traumatic optic neuropathy. DESIGN: Observational case report. METHODS: A patient presented with visual loss after an accident. Scanning laser polarimetry was performed. RESULTS: Thickness of the retinal nerve fiber layer increased immediately after the trauma but then progressively decreased. Severe loss was observed at day 90 and then ceased. Enlargement of the optic disk cup was also observed. CONCLUSIONS: This is the first report documenting early transient increase followed by progressive loss of the retinal nerve fiber layer in traumatic optic neuropathy.

Adolescent↗
PubMed1996

Measurement by nerve fiber analyzer of retinal nerve fiber layer thickness in normal subjects and patients with ocular hypertension.

PURPOSE: To measure retinal nerve fiber layer (NFL) thickness in normal subjects and patients with ocular hypertension and examine the relationship between age and normal NFL thickness. METHODS: Nerve fiber layer thickness was determined by scanning laser polarimetry in 210 normal subjects and 100 patients with ocular hypertension. Relative ratios for the superior and inferior NFLs were calculated by dividing the NFL values of the respective regions by the nasal value. RESULTS: Mean superior NFL in normal subjects measured 2.5 (95% confidence interval [CI], 1.3 to 3.7), and mean inferior NFL, 2.4 (95% CI, 1.2 to 3.6). Regression analysis showed a gradual decrease in NFL thickness with increasing age. In the patients with ocular hypertension, mean superior and inferior NFL were significantly lower compared with those of normal subjects: superior, 1.6 (95% CI, 0.4 to 2.8) and inferior, 1.6 (95% CI, 1.0 to 2.2). Of the patients with ocular hypertension, 58 of 100 (58%) had an abnormal NFL parameter. CONCLUSIONS: Normograms we obtained for NFL as determined by scanning laser polarimetry may serve as reference points for future studies. Patients with ocular hypertension had a significantly lower NFL thickness, although there was some overlap in resulting measurements with those of normal subjects. The Nerve Fiber Analyzer may be useful for individual follow-up of people at risk for glaucoma; however, its role as a screening instrument requires further study.

Adult↗
PubMed1999

Retinal nerve fiber layer measurement by nerve fiber analyzer in normal subjects and patients with glaucoma.

OBJECTIVE: To identify the pattern of retinal nerve fiber layer (RNFL) loss in glaucoma using the Nerve Fiber Analyzer (NFA). DESIGN: Case-control study. PARTICIPANTS: A total of 80 normal and 75 age- and race-matched chronic open-angle glaucoma subjects were recruited. INTERVENTION: The RNFL thickness was assessed with a scanning laser polarimeter (Nerve Fiber Analyzer GDX, Laser Diagnostic Technologies Inc., San Diego, CA). Analysis of variance was used to compare the corresponding RNFL measurement indices of the different groups. MAIN OUTCOME MEASURES: Superior/nasal (S/N) and inferior/nasal (I/N) ratios of NFA are sensitive parameters to differentiate between glaucoma and nonglaucoma subjects. RESULTS: Peripapillary RNFL measurements at the superior and inferior regions were significantly lower in the glaucoma group (P<0.001) but were similar in temporal and nasal regions (P>0.05). Using nasal value as reference, S/N and I/N ratios were significantly lower in the glaucoma groups (P<0.001) and also decreased with increasing severity of glaucoma. CONCLUSIONS: In glaucoma, RNFL was more susceptible to loss in the superior and inferior regions than in the nasal and temporal regions. The S/N and I/N ratio parameters provided by the NFA appeared to give further discriminating ability in early glaucoma.

Adult↗
PubMed2001

Polarimetric nerve fiber analysis in patients with peripapillary myelinated retinal nerve fibers.

PURPOSE: The aim of this study was to compare the RNFL thickness in eyes with myelinated retinal nerve fibers (MRNF) and age, sex-matched controls using scanning laser polarimetry. METHODS: Seventeen patients with MRNF underwent a comprehensive ophthalmological examination including automated visual field testing, and scanning laser polarimetry with Nerve Fiber Analyser (NFA II). Twenty eyes with MRNF from 17 patients were available for the study. Sixteen healthy, age and sex-matched subjects were taken as controls. Retinal nerve fiber thickness measurements of the four sectors (superior, inferior, nasal, temporal) and along the whole circumference of the optic disc were obtained for affected and control eyes, and compared. RESULTS: Inferior average and inferior integral parameters of the NFA revealed significantly thinner RNFL thickness measurements in eyes with inferiorly located MRNF compared to controls. CONCLUSION: Retinal myelination alters the birefringent property of the RNFL, and results in diminished thickness measurements. Hence, NFA measurements in patients with MRNF may not be reliable.

Adult↗
PubMed2003

FHL3 is an actin-binding protein that regulates alpha-actinin-mediated actin bundling: FHL3 localizes to actin stress fibers and enhances cell spreading and stress fiber disassembly.

Four and a half LIM domain (FHL) proteins are members of the LIM protein superfamily. Several FHL proteins function as co-activators of CREM/CREB transcription factors and the androgen receptor. FHL3 is highly expressed in skeletal muscle, but its function is unknown. FHL3 localized to the nucleus in C2C12 myoblasts and, following integrin engagement, exited the nucleus and localized to actin stress fibers and focal adhesions. In mature skeletal muscle FHL3 was found at the Z-line. Actin was identified as a potential FHL3 binding partner in yeast two-hybrid screening of a skeletal muscle library. FHL3 complexed with actin both in vitro and in vivo as shown by glutathione S-transferase pull-down assays and co-immunoprecipitation of recombinant and endogenous proteins. FHL3 promoted cell spreading and when overexpressed in spread C2C12 cells disrupted actin stress fibers. Increased FHL3 expression was detected in highly motile cells migrating into an artificial wound, compared with non-motile cells. The molecular mechanism by which FHL3 induced actin stress fiber disassembly was demonstrated by low speed actin co-sedimentation assays and electron microscopy. FHL3 inhibited alpha-actinin-mediated actin bundling. These studies reveal FHL3 as a significant regulator of actin cytoskeletal dynamics in skeletal myoblasts.

Actinin↗