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PubMed2001

Pivotal role of capsaicin-sensitive primary afferents in development of both heat and mechanical hyperalgesia induced by intraplantar bee venom injection.

To investigate the roles of primary afferent fibers in development of the bee venom (BV)-induced persistent spontaneous nociception (PSN) and hyperalgesia (HA), the sciatic nerve or both the sciatic and saphenous nerves of rats were topically treated with capsaicin respectively under pentobarbital anesthesia to destroy the capsaicin-sensitive primary afferent (CSPA) fibers. Effect of the sciatic nerve capsaicin on the formalin-induced PSN was also evaluated. Destruction of the CSPA fibers of the sciatic nerve or both the sciatic and saphenous nerves only produced 34 or 69% inhibition of the mean total number of 1 h BV-induced paw flinches. However, the total number of 1 h formalin-induced paw flinches was inhibited by 90% (85% for phase 1 and 91% for phase 2). In naïve rats, destruction of the CSPA fibers of the sciatic nerve caused 237 and 60% increase in paw withdrawal thermal latency (PWTL) to radiant heat in the injection site (paw pad) and at the heel of the treated hind paw compared to the baseline values. However, it was without significant influence upon the PWTL in the non-treated side or the paw withdrawal mechanical threshold (PWMT) to von Frey filament stimuli in both hind paws. In the BV-treated rats, the CSPA fiber destruction of the sciatic nerve completely blocked development of the heat and mechanical HA in the BV injection site. However, the reduction in either PWTL (drop to baseline level) or PWMT (drop by 56% from the baseline level) at the heel of the BV-treated side was not affected by this treatment. However, destruction of the CSPA fibers of both the sciatic and saphenous nerves was able to block development of both heat and mechanical HA in the whole BV-treated hind paw and heat hyperalgesia in the non-injected hind paw. Taken together, we conclude that: (1) the CSPA (C- and A delta-) fibers play a pivotal role in mediation of either the heat or the mechanical hyperalgesia induced by s.c. BV; (2) the CSPA fibers may play a crucial role in mediation of the formalin-induced PSN, but play a partial role in the BV-induced nociceptive process; (3) in addition to the sciatic nerve, the saphenous nerve is also involved in mediation of the BV-induced PSN as well as heat and mechanical hyperalgesia, while it is not likely to be involved in the formalin-induced nociception.

Administration, Topical↗

PubMed1995

Synaptophysin and GAP-43 proteins in efferent fibers of the inner ear during postnatal development.

A rearrangement of afferent and efferent fibers occurs in the postnatal development of the inner ear. Growth and synaptogenesis was explored during this critical period by immunohistochemically monitoring the expression of GAP-43 and synaptophysin. Both proteins were colocalized in efferent fibers beyond postnatal day 3 (pn3). Two distinct synaptophysin- and GAP-43-positive fibers innervated different parts of inner hair cells in the first and second postnatal weeks, respectively. GAP-43-positive efferents projecting to outer hair cells upregulated synaptophysin with base to apex gradient between postnatal day 5 and postnatal day 14. In efferents projecting to outer hair cells GAP-43 was downregulated about 6 days beyond synaptogenesis. In efferents projecting to inner hair cells, however, GAP-43 remained upregulated even beyond pn18, indicating continuous synapse replacement of this fiber type. Both proteins thus improved as excellent markers for growth and synaptogenesis of distinct postnatal efferent fibers.

Animals↗

PubMed1996

alpha 2-Adrenergic receptor binding in canine Purkinje fibers.

Autoradiograms were developed from free running strands of Purkinje fibers and from left ventricular myocardium of dog hearts exposed to [7-methoxy-3H]prazosin or [O-methyl-3H]yohimbine in the presence or absence of excessive non-radioactive ligands. Both Purkinje fiber and ventricular myocardium show high density, tissue-specific binding to [3H]prazosin. In contrast, high density, tissue-specific binding to [3H]yohimbine was present in Purkinje fibers but not in ventricular myocardium. Membrane fractions showed high affinity, saturable, and displaceable binding with [3H]yohimbine in preparations from canine cardiac Purkinje fibers but not those from canine cardiac ventricular myocardium. Scatchard analysis of the canine Purkinje membrane alpha 2-adrenergic receptor binding showed a Bmax of 54.9 fmol/mg protein with a Kd of 6.25 nM. These results confirm the electrophysiological findings that post-junctional alpha 2-adrenergic receptors are present in Purkinje fibers.

Adrenergic alpha-Antagonists↗

PubMed1991

Preparation of radiolabeled bioactive asbestos fibers.

We have developed an efficient procedure to radiolabel asbestos fibers while retaining the bioactivity of the fibers. The fibers are labeled with 68Ge. The 68Ge decays into 68Ga, which then can be detected by its characteristic positron emission. Both chrysotile and crocidolite asbestos, a serpentine and an amphibole, respectively, were radiolabeled successfully. Mild reaction conditions and short reaction times were found under which approximately 90% of the added 68Ge and 68Ga bound to the fibers. The radiolabel was retained even after washing the fibers extensively with physiologic buffers. The effects of the labeling on the bioactivity of the fibers were evaluated in an in vitro assay using guinea pig alveolar macrophages as a target cell. Labeled chrysotile fibers were found to retain greater than 95% of their ability to stimulate these cells. The labelling procedure described in this study should be useful in preparing labeled fibers to investigate both in vitro and in vivo phenomena.

Animals↗

PubMed1991

Postnatal development of the noradrenergic projection from locus coeruleus to the olfactory bulb in the rat.

Norepinephrine (NE) may play a role in the developing brain by modulating synaptic plasticity during critical periods of circuit formation (Kasamatsu and Pettigrew, 1976; 1979; Bear and Singer, 1986). In the olfactory bulb, NE input from the locus coeruleus (LC) appears to be necessary for the newborn rat to form a learned odor preference (Sullivan and Leon, 1986; Wilson and Leon, 1988; Sullivan et al., 1989). However, little is known about the development of NE innervation of the olfactory bulb. Thus, it is not clear how the maturation of the LC projection to the bulb correlates with the formation of olfactory bulb circuits during the period when NE modulates early olfactory learning. In this study, the postnatal development of the NE input from the LC to the main and accessory bulbs was characterized with tract tracing, immunocytochemistry, and quantitative image analysis methods. By birth there is already a substantial input to the olfactory bulb from the LC; as many as 200 LC neurons can be retrogradely labelled with wheatgerm agglutinin-horseradish peroxidase injection in the olfactory bulb. This compares with an estimated 400-600 neurons labelled by similar procedures in adult rats (Shipley et al., 1985). In order to study the development of NE fibers innervating the olfactory bulb, immunocytochemistry with antibodies to dopamine-beta-hydroxylase was employed. Image analysis was used to facilitate visualization and to quantitate the development of fiber densities. At birth, immunocytochemically labelled NE fibers were identified in all layers of the main and accessory olfactory bulb. The innervation was strongly preferential for infraglomerular layers at all stages of postnatal development. The fibers were densest in the internal plexiform and granule cell layers, less dense in the external plexiform layer, and sparse in the glomerular layer. The density of the fibers increased during development. There were no significant shifts in the relative distribution of the fibers in different layers of the bulb during development. This consistent laminar innervation by NE fibers suggests that if these fibers have a developmental role, their influence is probably limited to neuronal elements in inframitral cell layers.

Animals↗

PubMed1977

Normal nerve fibers in the barrel region of developing and adult mouse cortex.

The pattern of normal nerve fibers associated with barrel-shaped structures in the somatosensory cortex of both young and adult mice, has been studied using a reduced silver method. In adult animals, the "barrel" sides and septa can be seen to contain densely packed bundles of nerve fibers running vertically between layers III and V. In parasagittal sections, these fibers appear as very dark bands between adjacent barrels, while in tangenital sections the fibers, cut in cross-section, appear as rings of dark spots concentrated around the barrel edges. In contrast to this, barrels in immature animals have dark, evenly stained centers and pale, cell dense sides. This immature pattern can first be distinguished in 2-day-old animals and persists until 18 to 19 days. Between 18 and 24 days a change from the immature to the adult pattern occurs with the appearance of darkly stained, fine fibers within layer IV, particularly within the barrel sides. It is suggested that the immature pattern is due, primarily, to the staining of thalamic afferents while the adult pattern appears with the development of intracortical and association fibers. Electron microscopy, on tissue previously treated by the silver method, shows that the silver deposits are mainly attached to longitudinal elements of the axoplasm and not associated with myelin. This may explain the success of this method in showing fibers in young, unmyelinated brains.

Age Factors↗

PubMed1993

Epilepsy induced collateral sprouting of hippocampal mossy fibers: does it induce the development of ectopic synapses with granule cell dendrites?

In the present study, using Golgi and electron microscopy techniques, experimentally induced epilepsy (kindling and kainate treatment) elicited collateral sprouting of mossy fibers in rat hippocampus. Collateral branches invade the hilus, cross the granule cell layer, and distribute throughout the inner third of the molecular layer. These newly developed collaterals may acquire the typical features of mossy fibers including giant fiber varicosities (mousses), although the mean surface of these mousses was thinner in these collaterals than in terminal branches. Granule cell dendrites may develop giant thorny excrescences, suggesting that the targets of these collaterals are granule cells. Giant synaptic boutons appear in the inner third of molecular layer of epileptic rats. These boutons acquire the morphological features of mossy fiber boutons and made multiple synaptic contacts with dendritic spines. The analysis of the profile types suggests that some of the newly developed collateral mossy fibers made hypotrophic synaptic contacts.

Animals↗

PubMed1998

Development and cellular applications of fiber optic nitric oxide sensors based on a gold-adsorbed fluorophore.

A new design for optochemical sensors has been applied to the development of a nitric oxide selective fiber optic sensor. This sensor is composed of a fluorescein derivative dye attached to colloidal gold. The fluorescein dye rearranges as nitric oxide adsorbs onto the gold, inducing a decrease in the fluorescence intensity of the dye. This mechanism has allowed preparation of fiber optic dye-based nitric oxide sensors, which have been made ratio-metric by addition of reference dye microspheres. Previously developed fast, selective optical sensors for detection of aqueous nitric oxide involved a protein, such as cytochrome c'. The new fluorescein derivative chemical sensors have characteristics similar to those of the protein-based biosensors, including fast response times, excellent selectivity, and complete reversibility. In addition, the chemical sensors have advantages such as greater stability and commercially available components. These sensors were utilized to measure nitric oxide production by BALB/c mouse macrophages.

Adsorption↗

PubMed2000

Development of catheters with low fiber background signals for Raman spectroscopic diagnosis applications.

Utilization of optical-fiber catheters can turn the Raman spectroscopy system into a powerful remote biomedical diagnostic probe. An in vivo (a qualitative and a quantitative) biochemical diagnosis of biotissues is possible by developing the Raman-fiber probes with a good flexibility and less background signals generated in the probes themselves. Considering the isotropic nature of Raman scattering, the amount of Raman signal guided through the fiber is expected to depend on the numerical aperture (NA) of the fiber. To study the dependence for catheter probes experimentally, various flexible probes (with small diameter fibers) with different combinations of numerical apertures and with different assembling materials (biocompatible) have been developed. The catheter probes have been characterized by collecting the near infrared excited Raman scattered light from cholesterol powder. The results demonstrate that the catheters with a combination of lower NA (0.12) fibers used for laser excitation and relatively higher NA (0.22) fibers for Raman signal collection will have lower background signals generated in the probes. Furthermore, the catheters with a black Teflon tubing cover and black epoxy resin adhesives were found to give better results.

Adhesives↗

PubMed2006

[Developments of liquid-phase microextraction based on hollow fiber].

The liquid-phase microextraction (LPME), based on disposable hollow fiber, has been developed to be a new environmentally benign sample preparation technique which incorporate sampling, extraction and concentration into a single step. The novel technique can be easily manipulated in combination with high performance liquid chromatography, gas chromatography and capillary electrophoresis, and can provide excellent sample clean-up effect and high degree of extraction recovery and enrichment. It is proved to be simple, low-cost and virtually solvent-free. The extraction set-up, extraction mode, basic principles and recent applications of the hollow fiber-based liquid-phase microextraction are reviewed.

Analytic Sample Preparation Methods↗

PubMed1993

CD24, a signal-transducing molecule expressed on human B lymphocytes, is a marker for human regenerating muscle.

The expression of the CD24 molecule, a glycoprotein expressed at the surface of most B lymphocytes and differentiating neuroblasts, was studied in developing nerve and muscle (after 16 weeks of gestation), normal adult and various diseased human muscles using immunohistochemistry and Western blot analysis. Immunohistochemical studies demonstrated that: (1) in developing muscles, fibers did not express CD24, whereas only some mesenchymal areas, also expressing neural cell adhesion molecule (N.CAM) and vimentin, and developing nerves were positive; (2) in normal adult muscles, CD24 immunoreactivity was observed only in some unmyelinated nerve fibers--intra and extra fusal muscle fibers, satellite cells and neuromuscular junctions were negative; and (3) in all diseased muscles studied here, CD24 expression was always associated with a subpopulation of regenerative fibers. These fibers also expressed vimentin, desmin, developmental myosin heavy chain, N.CAM and its polysialylated isoforms (PSA-N.CAM). The number of CD24-positive fibers was always lower than that of PSA-N.CAM-positive fibers. Denervated fibers and vacuolated muscle fibers never expressed CD24. Western blot analysis indicated that the apparent molecular mass of CD24 antigen was different between muscle and developing nervous tissues, suggesting that CD24 glycosylation is tissue specific. Since the molecule was not expressed in developing human muscle fibers, it strongly suggests that regenerative and fetal myotubes are different with respect to the CD24 molecule expression.

Adult↗

PubMed1999

Developmental expression of corticotropin-releasing factor in the postnatal murine cerebellum.

Corticotropin-releasing factor (CRF) is present in climbing and mossy fibers and both have a distinct pattern of distribution in the adult cerebellar cortex. The intent of this developmental study is to determine when the lobular pattern of CRF distribution emerges, and to analyze the morphogenesis of CRF immunoreactive climbing and mossy fibers in individual cerebellar lobules. Between postnatal day (P)0 and P3, CRF-immunoreactive (IR) punctate elements are present throughout the cerebellum. By P3, there is a decrease in the density of staining in the white matter and punctate elements become concentrated within the developing cortex. Between P3 and P7 CRF-IR, varicosities circumscribe Purkinje cell bodies, and are present in the internal and external granule cell layers. Between P10 and P12, there is a major reduction in the density of CRF-IR puncta, especially in the internal and external granule cell layers. Varicosities remain around Purkinje cell bodies and some extend into the molecular layer. During this interval, CRF-IR profiles are first evident in axonal configurations characteristic of developing climbing fibers, although there are lobular differences in the degree of maturation of this afferent system. Axonal enlargements characteristic of immature mossy fibers can first be seen at P10 in lobules IX and X; they cannot be differentiated until P12-14 in more rostral or lateral lobules. CRF-IR fibers in lobules IX and X, the vestibulocerebellum, develop into mature climbing and mossy fibers before any other area of the cerebellum. In other lobules of the cerebellum the gradient of maturation for these axonal phenotypes is from medial to lateral and posterior to anterior. Between P10 and P12, CRF-IR climbing fibers are present in all lobules of the cerebellum. After P12, few climbing fibers are observed in the anterior lobe of the cerebellum at midvermal levels; those present are only faintly immunolabeled. Based on its early expression and uniform distribution between P0 and P10, CRF could have a role in cerebellar development. After this age, as climbing and mossy fiber terminal phenotypes mature, and the differential adult patterns of distribution emerge, CRF likely begins to function as a neuromodulator as has been shown in the adult cerebellum.

Animals↗

PubMed1977

Development of action potential in larval muscle fibers in Drosophila melanogaster.

In the presence of tetraethylammonium or barium ions, the larval muscle fibers of Drosophila melanogaster were found to produce an all-or-none action potential operated by the calcium channels. The development of this distinctive membrane property during the maturation of muscle cells was studied by measuring the maximum rate of rise of the action potential in the larval muscle fibers at different stages of development from the sixteenth to ninety-sixth hours after hatching. The value increased significantly with age until a peak was reached at the sixty-fourth hour, although it became lower again as puparium formation neared at about the ninety-sixth hour. This suggests that during larval development the muscle fibers develop the ability to generate an action potential due to an inward current through the calcium channels, although the ability became lower at the later stage of larval development.

Action Potentials↗

PubMed2001

Development of a new hollow fiber silicone membrane oxygenator: in vitro study.

An experimental silicone hollow fiber membrane oxygenator for long-term extracorporeal membrane oxygenation (ECMO) was developed in our laboratory using an ultrathin silicone hollow fiber. However, the marginal gas transfer performances and a high-pressure drop in some cases were demonstrated in the initial models. In order to improve performance the following features were incorporated in the most recent oxygenator model: increasing the fiber length and total surface area, decreasing the packing density, and modifying the flow distributor. The aim of this study was to evaluate the gas transfer performances and biocompatibility of this newly improved model with in vitro experiments. According to the established method in our laboratory, in vitro studies were performed using fresh bovine blood. Gas transfer performance tests were performed at a blood flow rate of 0.5 to 6 L/min and a V/Q ratio (V = gas flow rate, Q = blood flow rate) of 2 and 3. Hemolysis tests were performed at a blood flow rate of 1 and 5 L/min. Blood pressure drop was also measured. At a blood flow rate of 1 L/min and V/Q = 3, the O2 and CO2 gas transfer rates were 72.45 +/- 1.24 and 39.87 +/- 2.92 ml/min, respectively. At a blood flow rate of 2 L/min and V/Q = 3, the O2 and CO2 gas transfer rates were 128.83 +/- 1.09 and 47.49 +/- 5.11 ml/min. Clearly, these data were superior to those obtained with previous models. As for the pressure drop and hemolytic performance, remarkable improvements were also demonstrated. These data indicate that this newly improved oxygenator is superior to the previous model and may be clinically acceptable for long-term ECMO application.

Animals↗

PubMedDate not supplied

Intestinal obstruction from cecal bezoar; a complication of fiber-containing tube feedings.

Dietary fiber increases stool bulk, regulates bowel transit time, and decreases intraluminal pressure. Because these actions constitute a natural way to stop diarrhea, a frequent problem with tube feedings, enteral tube feeding manufacturers have marketed several fiber-containing formulae. While bulk-forming agents such as fiber may not be appropriate for every tube-fed patient, we were unable to find any published contraindications to the use of fiber-containing enteral products. We present the case of a seriously ill man who received a fiber-containing tube feeding while also getting intestinal motility-suppressing medications. A large fiber bezoar developed, with resultant mesenteric hemorrhage. We conclude that fiber-containing tube feedings are contraindicated in certain types of patients.

Bezoars↗

PubMed1997

Development of a urinary riboflavin adherence marker for a wheat bran fiber community intervention trial.

Development of a reliable marker of adherence to high-fiber diets is essential for accurately assessing dietary fiber intake in community interventions and clinical trials. The objective of this study was to evaluate the feasibility of using a riboflavin tracer incorporated into wheat bran cereal to determine fiber intake and compare results to the more traditional methodology of measuring stool weight. The inpatient phase of the study established that the excretion of urinary riboflavin was highly correlated with the dose of the riboflavin-spiked wheat bran cereal (r = 0.95, P < 0.005) and could be used as a biomarker to validate fiber supplement intake. The outpatient clinical intervention included a group of seven African-American men and women, who were asked to incorporate 1/2 cup of wheat bran cereal (11.6 g of dietary fiber) into their daily diet for a 6-week period. The cereal was spiked with a 28-mg dose of riboflavin. Baseline measurements of urinary riboflavin and stool weight were compared to postintervention levels. Comparison of pre- and postintervention measures of riboflavin excretion showed a significant increase (0.8 +/- 0.1 versus 6.0 +/- 0.6 mg/day, P < 0.02), which confirmed a high level of adherence to the dietary intervention. Although wet stool weights at baseline were significantly lower than postintervention (106 +/- 20 versus 146 +/- 23 g/day; P < 0.03), differences in dry stool weights did not reach significant levels (28 +/- 4 versus 33 +/- 5 g/day, P < 0.30). Furthermore, pre- and poststool measurements overlapped and could not provide definitive data on participant adherence. These results indicate that the riboflavin tracer was a more sensitive biomarker of wheat bran fiber supplementation than stool weight and provided an accurate method for validating adherence to the dietary intervention. A riboflavin marker provides a valid technique for adherence assessment in large-scale community trials, in which collection of 3-day fecal samples is not a manageable option.

Aged↗

PubMed1987

The effect of [Mg2+] on the Ca2+ dependence of ATPase and tension development of fast skeletal muscle. The role of the Ca2+-specific sites of troponin C.

Conflicting reports have appeared concerning the effect of [Mg2+] on muscle activity. Several groups have found that increasing [Mg2+] produces a right-ward shift of the pCa-tension curve, while others have found no effect of [Mg2+] on myofibrillar ATPase activity. The present study is a careful evaluation of the effect of [Mg2+] on myofibrillar ATPase, skinned fiber tension development, TnCDANZ (troponin C (TnC)-labeled with 5-dimethylaminonaphthalene-1-sulfonyl aziridine) fluorescence, and simultaneous TnCDANZ fluorescence and tension development in the same fiber. A small effect of [Mg2+] on both ATPase and tension development was found with an apparent association constant of about 2 X 10(2) M-1. The Ca2+ dependence of TnCDANZ fluorescence was similarly effected by [Mg2+], either alone or when incorporated into TnC-depleted skinned fibers (K'Mg approximately equal to 2-3 X 10(2) M-1), suggesting that the effect of [Mg2+] on activity is due to an effect of [Mg2+] on Ca2+ binding to the Ca2+-specific sites of TnC. It is not yet clear whether this effect of [Mg2+] is through direct competition at the binding sites or through indirect effects. In either case, the calculated effect of physiological [Mg2+] is so small that the regulatory sites of TnC can still be considered "Ca2+-specific." In addition, a slightly greater effect of [Mg2+] on tension development (K'Mg = 4.62 X 10(2) M-1) was observed only for very low levels of [Mg2+], which might suggest an additional effect of Mg2+ on tension development which is saturated by millimolar Mg2+.

Animals↗

PubMed1991

Glial cell differentiation in neuron-free and neuron-rich regions. I. Selective appearance of S-100 protein in radial glial cells of the hippocampal fimbria in human fetuses.

The proliferative cells of the developing hippocampal fiber tract fimbria have only the potential for gliogenesis; thus the developing fimbria provides an ideal model for the study of the development and differentiation of its constituent glial cells. In the first stage of development, the fimbrial primordium can be distinguished morphologically, and during the second stage, the fimbria becomes a well-defined fiber tract. In the third stage, a divergent immunocytochemical staining pattern clearly demarcates the neuron-free fimbria from the hippocampus, where a mixed neuro- and gliogenesis occurs. The distinct expression of S-100 protein in radial glial cells is restricted to the fimbria. During the final stage of development, the ventricular lining of the fimbria will mature into an ependyma. It is suggested that the S-100-positive radial glial cells of the fimbria, which probably retain their proliferative capacity, represent a homogeneous population of precursor cells that will give rise to the glial cells of the adult fimbria. The appearance of S-100 in the fimbrial radial glial cells seems to occur coincidentally with the establishment of hippocampal commissural connections. The S-100-positive radial glial cells of the fimbria may guide and segregate populations of growing axons by providing physical and chemical cues. Thus, S-100 protein per se seems to be intimately involved in modulation and regulation of axonal growth and patterning.

Axons↗