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At least 613 records · Page 34Linked to original sources
PubMed2006

Hollow polycarbonate fiber for Er:YAG laser light delivery.

We developed hollow fibers with polycarbonate (PC) capillaries for use as a supporting tube. The PC capillaries were prepared by using a glass-drawing technique. Hollow PC fibers are safer and more flexible than hollow glass fibers because no fragments are released when the fibers are broken in various applications. Inner coating layers of silver and cyclic olefin polymer (COP) enhanced the reflection rate at the Er:YAG laser light wavelength. Using these fibers, we attained low loss for Er:YAG laser light transmission. By adjusting the drawing temperature in the fabrication of the PC capillaries, we created a smooth inner surface and uniform PC capillaries. We also demonstrated low-loss properties for visible pilot beams.

Equipment Design↗
PubMed1997

Afferent large fiber polyneuropathy predicts the development of postherpetic neuralgia.

Acute zoster infection may be followed by a chronic pain syndrome, i.e., postherpetic neuralgia (PHN). Besides older age, the intensity of pain and neuronal damage within the acutely affected body region are regarded as predictors or risk factors for PHN. As an alternative approach an underlying peripheral polyneuropathy may be considered as potential co-factor. Is a preexisting generalized impairment of certain fiber classes important in initiating chronic pain states after subsequent localized nerve lesion due to zoster infection? Neurophysiological tests of different efferent and afferent small and large fiber systems were performed prospectively at unaffected body regions in patients with acute herpes zoster. Patients that were still in pain 6 months later (PHN, n = 17) and pain free patients (non-PHN, n = 17) were compared regarding the results obtained during the acute phase. Both groups were age matched. Nociceptive C-fiber function was assessed at the forearm by quantitative measurement of the axon reflex vasodilatation and flare induced by histamine iontophoresis. Mechanosensitive A beta-fibers were tested at all extremities by quantitative vibrametry. Parasympathetic small fiber function was studied by heart rate variability tests. No clinically manifest polyneuropathy was present. However, in PHN risk patients considerably higher vibration detection thresholds in hands and feet were detected compared with non-PHN patients. Pathologic test results of vibration sense at the lower extremity predicted PHN with a sensitivity of 70%. Nociceptive C-fiber and parasympathetic fiber function demonstrated no significant differences in both groups. Acute zoster pain was slightly more intense in the PHN group. We concluded that (i) a mild generalized impairment of afferent A beta-fiber function (A beta-polyneuropathy) seems to be an important co-factor in the development of PHN and (ii) impairment of vibration sense, i.e., impairment of afferent A beta-fiber function, may be used as a predictor of PHN.

Acute Disease↗
PubMed2006

Release of bovine serum albumin from a hydrogel-cored biodegradable polymer fiber.

We have developed a novel biodegradable, polymeric fiber construct that is coextruded using a wet-spinning process into a core-sheath format with a polysaccharide pre-hydrogel solution as the core fluid and poly(L-lactic acid) (PLLA) as the sheath. The biodegradable, biocompatible fibers were extruded from polymeric emulsions comprised of solutions of various molecular weights of PLLA dissolved in chloroform and containing dispersed, protein-free aqueous phases comprising up to 10% of the emulsion volume. Biologically sensitive agents can be loaded via a dispersed aqueous phase in the polymer, and/or directly into the polysaccharide. We show that this core-sheath fiber format will load a model protein that can be delivered for extended periods in vitro. Bovine serum albumin (BSA) was loaded into the fiber core as a model protein. We have shown that the greater the volume of the protein-free aqueous phase dispersed into the polymeric continuous-phase emulsion, the greater the total release of BSA encapsulated by a core gel comprised of 1% sodium alginate solution. We conclude this fiber format provides a promising vehicle for in vivo delivery of biological molecules. Its biocompatibility and biodegradability also allow for its use as a possible substrate for tissue engineering applications.

Alginates↗
PubMed1996

DNA hydration studied by neutron fiber diffraction.

The development of neutron high angle fiber diffraction to investigate the location of water around the deoxyribonucleic acid (DNA) double-helix is described. The power of the technique is illustrated by its application to the D and A conformations of DNA using the single crystal diffractometer, D19, at the Institut Laue-Langevin. Grenoble and the time of flight diffractometer, SXD, at the Rutherford Appleton ISIS Spallation Neutron Source. These studies show the existence of bound water closely associated with the DNA. The patterns of hydration in these two DNA conformations are quite distinct and are compared to those observed in X-ray single crystal studies of two-stranded oligodeoxynucleotides. Information on the location of water around the DNA double-helix from the neutron fiber diffraction studies is combined with that on the location of alkali metal cations from complementary X-ray high angle fiber diffraction studies at the Daresbury Laboratory SRS using synchrotron radiation. These analyses emphasize the importance of viewing DNA, water and ions as a single system with specific interactions between the three components and provide a basis for understanding the effect of changes in the concentration of water and ions in inducing conformational transitions in the DNA double-helix.

Crystallography↗
PubMed1998

Developmental expression and location of IGF-I and IGF-II mRNA and protein in skeletal muscle.

To investigate the role of IGF in muscle development in vivo, developmental expression and location of IGF-I and -II protein and mRNA were examined in fetal, postnatal, and adult skeletal muscle. Muscle tissue was collected from 30-, 44-, 59-, 68-, 75-, 89-, and 109-d porcine fetuses, 21-d neonatal pigs, and 6-mo-old (adult) pigs. Relative amounts of IGF-II mRNA peaked (P < .05) in 59-d fetal muscle and decreased thereafter. Inversely, muscle IGF-I expression increased (P < .05) to maximal levels around birth. For in situ hybridization, frozen muscle tissue sections (10 microm) were hybridized with a hydrolyzed form of the same riboprobes or incubated with polyclonal or monoclonal antibodies to IGF-I or -II, respectively. The majority of IGF-I and IGF-II mRNA was localized to developing muscle fibers, whereas little signal was found in the surrounding connective tissues. Immunofluorescent localization of IGF-I and -II confirmed that muscle IGF are present in developing muscle fibers. Collectively, these data show that IGF-I and -II are expressed and produced primarily in muscle cells within developing muscle tissue and support the hypothesis that IGF-I and -II modulate fetal muscle development.

Animals↗
PubMed1990

Olivocerebellar fiber maturation in normal and lurcher mutant mice: defective development in lurcher.

Olivocerebellar fiber maturation was examined in normal and lurcher mutant mice between postnatal day 5 (P5) and P15, using the anterograde transport of wheat germ agglutinin-horseradish peroxidase (WGA-HRP) from the inferior olive. Immunocytochemistry for the Purkinje cell marker PEP-19 was used to demonstrate Purkinje cell development in the same material. In mutant and normal animals, a regional developmental variation is observed such that, when compared at a given age, cortex lining the vermal fissures appears developmentally advanced over cortex in the cerebellar hemispheres. In the primary fissure of the normal animals, the first recognizable Purkinje cell dendrites appear on P6, and the olivocerebellar fibers first enter the climbing stage of their development on P9. In lurcher animals Purkinje cell development proceeds on this schedule, but olivocerebellar fibers are never observed to enter the molecular layer. These afferents maintain dense perisomatic nests around Purkinje cells, even in P13-15 lurchers. Examination of P14 lurchers by transmission electron microscopy indicates that the olivocerebellar fibers form synapses on Purkinje cell somatic spines and that the basket cell axons fail to form their typical perisomal nests around Purkinje cells. In addition, parallel fibers can be observed to synapse on dendritic spines on the Purkinje cell primary dendrites. We interpret these results as indicating a recognition defect between olivocerebellar fibers and Purkinje cell dendrites. An analysis of this defect in lurcher may reveal how the normal transformation of olivocerebellar fibers, from perisomal to dendritic terminals, is achieved.

Animals↗
PubMed1992

Immunohistochemical study on development of serotonin-, substance P-, and enkephalin-positive fibers in the rat spinal motor nucleus.

Developmental changes in the coexistence of serotonin and substance P/enkephalin within single fibers of lamina IX of the rat lumbar spinal cord were examined by the use of a double-labelling immunohistochemical technique. On postnatal day (P) 0, 65.0% of immunoreactive varicosities contained only serotonin, and 21.3% of them had both serotonin and substance P. The coexistent ratio of serotonin and substance P in single fibers increased with development: 61.9% of serotonin positive varicosities co-contained substance P on P28, similar to the ratio found in adult animals (67.4%). The ratios of varicosities containing only substance P remained the same from P0 to adult stage (about 15%). Enkephalin positive immunoreactivity was not co-localized with serotonin positive varicosities at any stage of development. Although numerous serotonin positive fibers were found in lamina IX, only a few substance P and enkephalin positive fibers were observed in the same area on P0. The density of serotonin positive varicosities increased slightly by P28, whereas substance P and enkephalin positive fibers increased considerably by this age. Between P28 and the adult stage, the density of serotonin positive fibers decreased by about 50%. The cross sectional area of axonal varicosities containing serotonin- and substance P-like immunoreactivity was similar in both P0 and adult animals, whereas that of enkephalin positive fibers was different. We also examined the coexistence of serotonin and substance P within single neurons of the caudal raphe nuclei in P7 and adult animals, and found that the coexistent ratio significantly increased with development.

Aging↗
PubMed1977

Temperature-dependence of tension development by glycerinated muscle fibers of rabbit psoas in Mg-ITP solution.

The isometric tension of single fibers isolated from glycerinated rabbit psoas muscle was measured at various temperatures using Mg-ITP as a substrate. The tension developed in Mg-ITP decreased linearly as the temperature was reduced from 24 degrees C to 4 degrees C. Myosin formed the myosin--product complex predominantly via ATP hydrolysis at the burst site during Mg-ATP hydrolysis, irrespective of temperature, and the tension developed in Mg-ATP decreased linearly as the temperature decreased (Yoshida and Tawada (1976) J. Biochem. 80, 861). During Mg-ITP hydrolysis, myosin forms the myosin*-product complex predominantly at the burst site above 20 degrees C, while myosin forms the myosin*-substrate complex below 8 degrees C (Hozumi (1976) Eur. J. Biochem. 63, 241). However, the temperature dependence of tension development in Mg-ITP is linear, as with Mg-ATP, as mentioned above. This temperature dependence is not compatible with some muscle models which assume the formation of the myosin*-product complex by cross-bridges prior to combination with actin during contraction.

Animals↗
PubMed1990

Muscle fiber orientation in the development and regression of right ventricular hypertrophy in pigs.

The development and regression of right ventricular hypertrophy was investigated in 12 pigs with special reference to changes in ventricular function and myocardial fiber orientation. Nine ventricles were pressure-loaded by banding the pulmonary artery for 28-81 days, and four of them were then released from the load by removing the band. Right ventricular systolic pressure (RVSP), end-diastolic pressure (RVEDP) and end-systolic volume index (ESVI) increased significantly during banding and decreased after debanding. End-diastolic volume index (EDVI) and stroke volume index (SVI) showed no significant change during banding and after debanding. The weight of the right ventricle relative to both ventricles (RV/TV) and the thickness of muscle fibers were increased significantly in the loaded ventricles, and reduced again to the control level in ventricles released from the load. The intramyocardial distribution of angles (theta) of inclination of muscle fibers from the transverse plane of the outflow tract was estimated histometrically. There was a significantly larger proporation of circularly oriented fibers (magnitue of theta less than or equal to 30 degrees) in the pressure-loaded ventricles than in the control, whereas these fibers decreased again to the control level after removal of the pressure load. The present findings indicates that 1) the right ventricular hypertrophy induced by pressure loading is characterized not only by an increase in ventricular weight and muscle fiber thickness, but also by a change in intramyocardial fiber orientation, and 2) the hypertrophic right ventricle can regress both functionally and morphologically to a normal state after removal of the pressure load.

Animals↗
PubMed1990

Feasibility of using liquid crystals for the development of molecularly selective fiber-optic chemical sensors.

A new type of fiber-optic chemical sensor has been developed for the determination and differentiation of geometric isomers. The operation of the sensor is based upon the molecular-geometric-selective absorption of polynuclear aromatic hydrocarbons (PAH) on a liquid crystal. The selective interaction of a PAH with a liquid-crystal substrate causes quenching of the liquid-crystal fluorescence. Detection limits of such a device for PAH compounds approach 10(-10) mol/cm3; the sensor response time is about 2 min. Because the sensor is based upon physical absorption, it is reusable and reversible.

Fiber Optic Technology↗
PubMed1983

Structural alterations of peripheral nerve monogalactosylceramides during development and Wallerian degeneration.

The structural alterations of monogalactosylceramides in peripheral nerve were investigated during development, nerve fiber degeneration and regeneration. During early development, hydroxy cerebrosides and sulfatides were the main constituents of the monogalactosylceramides of immature rat sciatic endoneurium. The ratio of hydroxy to nonhydroxy cerebrosides decreased rapidly as myelination proceeded but remained fairly constant throughout adulthood. More than 50% of the adult content of endoneurial monogalactosylceramides was achieved before 21 days of age. The long-chain nonhydroxy fatty acids (above C21) had increased from under 20% to over 80% by day 20, while 24h:0 (h, hydroxy) had already reached approximately 50% of hydroxy cerebrosides by day 12. These results suggest that the biosynthesis of endoneurial monogalactosylceramides and fatty acid elongation take place preferentially at the time when peripheral nerve is undergoing active myelination. During Wallerian degeneration, the maximum decrease of monogalactosylceramides was associated temporally with axonal degeneration and demyelination and particularly with myelin conversion to sudanophilic lipids. By the time that nerve fiber regeneration was well established, both the cerebroside and sulfatide contents had returned to near control values. Cerebrosides and long-chain fatty acids (above C21) appear to be the most sensitive to fiber degeneration while fatty acid elongation is selectively increased during nerve regeneration.

Animals↗
PubMed1992

Development of a medical fiber-optic oxygen sensor based on optical absorption change.

A new fiber-optic oxygen sensor has been developed for use in medical applications. The sensor's viologen indicator becomes strongly absorbent after brief UV stimulation, and then returns to the transparent state. The rate of indicator return to transparency is proportional to the local oxygen concentration. Indicator absorbance is monitored with a red LED and receiving photodiode, and absorbance data are processed by a dedicated cpu. The solid-state sensor system has performance comparable to existing oxygen measurement techniques, and may be applicable for both in vitro and in vivo oxygen measurements.

Absorption↗
PubMed1990

Neuron migration within the radial glial fiber system of the developing murine cerebrum: an electron microscopic autoradiographic analysis.

The present analysis provides direct evidence in the mouse that in the course of course of neocortical histogenesis, contact between migrating neurons and the surfaces of radial glial fibers is both invariant and relatively selective. The analysis characterizes in detail the migratory behavior of the individual migrating cell with respect to the overall radial glial fiber system as this system varies systematically in its structure with ascent through the strata of the cerebral wall. A quantitative study of the relationships between the radial glial fibers confidently identified by their glycogen content and the migrating neurons marked autoradiographically by injection of [3H]thymidine was also performed at the ultrastructural level on tangential sections at different pallial levels in E16 and E17 embryos. The overall set of observations lend support to the hypothesis that radial glial fibers act specifically as guides to neuronal migration and illustrate the nature of the cell-to-cell interaction which serves this cellular process critical to neocortical histogenesis.

Animals↗
PubMed1999

Effect of long-term spontaneous recurrent seizures or reinduction of status epilepticus on the development of supragranular mossy fiber sprouting.

In a recent report we have shown that a protein synthesis inhibitor, cycloheximide (CHX), is able to block the mossy fiber sprouting (MFS) that would otherwise be triggered by pilocarpine (Pilo)-induced status epilepticus (SE), and also gives relative protection against hippocampal neuronal death. Under this condition animals still showed spontaneous recurrent seizures (SRS) which led us to question the role played by sprouted mossy fibers in generating those seizures. In both patients and animal models of epilepsy the relative contribution of SE (when present) and/or SRS for the development of MFS is not known. In the present study we investigated the relationship between MFS, SE and SRS, and evaluated whether the CHX-induced blockade of MFS was transient or permanent in nature. We performed a chronic study which included animals subject to Pilo-induced SE in the presence of CHX and sacrificed between 8 and 10 months later, and animals that were subject to Pilo-induced SE in the presence of CHX and underwent a reinduction of SE with Pilo, 45 days after the first induction, but this time in the absence of CHX. Re-induction of SE or a long period of chronic seizures, were able to trigger supragranular MFS even in animals where the first (or only) SE event was triggered in the presence of CHX. MFS did not show any association with the frequency of SRS, and thus seemed to depend more critically on time. Our current findings allow us to suggest that MFS are neither the cause nor the consequence of SRS in the pilocarpine model.

Animals↗
PubMed1988

Oxidative potential in developing rat diaphragm, EDL, and soleus muscle fibers.

To examine the effect of postnatal development on changes in oxidative potential of fibers of specific types (I, IIa, IIb, and IIc) in the rat diaphragm, determinations of succinate dehydrogenase (SDH) activity were made using microphotometric measures of optical density. Samples of the costal region of the diaphragm were extracted from 56 male Wistar rats ranging in age from 8 to 85 days and subgrouped into seven developmental periods (1, 2, 3, 4, 6, 9, and 12 wk). For type I fibers, increases of 17% (P less than 0.05) in SDH activity occurred during 2nd wk, remained elevated through 4th wk, and increased further (P less than 0.05) to 137% of 1-wk values by the end of 6th wk. No further increases were noted between 6 and 12 wk. A similar maturational trend was evident for type IIa fibers, although SDH activities remained higher throughout development when compared with type I fibers. In contrast, SDH in type IIb fibers, although increasing by 14% during the first two measurement weeks (P less than 0.05), declined from 6 to 9 wk before ultimately reaching a value similar to 3 wk. SDH activity was also assessed in a typical slow- (soleus) and fast-twitch (extensor digitorum longus, EDL) muscle of the hindlimb to contrast their development with that of the diaphragm. Generally, SDH in type I and IIa fibers was approximately 40 and 20% higher, respectively, in the diaphragm than in matched fiber types in the other muscles throughout development (diaphragm greater than EDL greater than soleus).(ABSTRACT TRUNCATED AT 250 WORDS)

Adenosine Triphosphatases↗
PubMedDate not supplied

Soleus muscle alterations in spontaneously hypertensive rats are not dependent on activation of beta 2-adrenergic receptors.

The effects of selective beta 2-adrenergic blockade with ICI 118,551 on the histochemical, biochemical, and contractile properties of slow-twitch soleus muscle from spontaneously hypertensive (SHR) and normotensive (WKY) rats were examined from birth to 8-10 weeks of age. Chronic treatment of normotensive rats with ICI 118,551 caused an impairment in the differentiation of slow type fibers during development but failed to alter the fiber type distribution of hypertensive rats. beta 2-Adrenoreceptor blockade was ineffective in reducing the enhanced glycolytic and oxidative capacities of soleus in hypertensive rats. The suggestion can be made that beta 2-adrenoreceptor activation is not responsible, at least directly, for the histochemical and biochemical alterations of slow muscle from hypertensive rats.

Adrenergic beta-Antagonists↗
PubMed2002

Complexities in ETS-domain transcription factor function and regulation: lessons from the TCF (ternary complex factor) subfamily. The Colworth Medal Lecture.

The ETS-domain transcription factor family can be divided into a series of subfamilies. Elk-1 represents the founding member of the ternary complex factor (TCF) subfamily. By focusing on the TCF subfamily, we can demonstrate the complexities that exist in the function and regulation of ETS-domain transcription factors. This article focuses on Elk-1 in detail and summarizes the functions of other TCFs. The key themes covered include the domain structure of the TCFs, the mechanisms of complex formation with serum response factor, regulation of TCFs by mitogen-activated protein kinase cascades, and transcriptional regulatory properties of the TCFs. Finally, the emerging role of the TCFs in vivo is discussed. A picture is developing indicating that, while these proteins exhibit significant sequence and functional conservation, key differences in their structure and regulation are being identified which may relate to unique functions of these proteins in vivo.

Amino Acid Sequence↗