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At least 91 records · Page 5Linked to original sources

PubMed1995

Immunocytochemical localization of growth-associated protein GAP-43 in early human development.

Fibers labelled with antibody to the growth associated protein (GAP-43) were observed as early as 4 gestational weeks (g.w.) in the nervous system of human embryos. At 6 g.w. these fibers could be traced throughout the brainstem and the diencephalon. None of the immunolabeled fibers entered the telencephalic wall at that point, but 2 weeks later at 8 g.w., GAP-43 positive fibers were observed below the newly formed cortical plate of the cerebral cortex. GAP-43 positive fiber bundles had the same distribution as those previously labeled with tyrosine hydroxylase antibodies at the same age. These results strongly suggest that this growth associated protein is localized in the early growing dopaminergic fibers.

Brain↗

PubMed2003

Targeted retentive device for oro-dental infections: formulation and development.

Fibers loaded with amoxycillin trihydrate were prepared for oro-dental infections using melt spinning technique. Ethylene vinyl acetate, a biocompatible polymer was used for providing controlled release effect over a period of several days. The fibers were evaluated for in vitro release in alkaline borate buffer pH 8.1 in a biological shaker which was rotated at 50 rpm at 37 degrees C. In situ studies were carried out in continuous flow through apparatus which simulated the conditions of periodontal pocket. Microbiological evaluation was carried out on strains commonly implicated in oro-dental infections namely S. aureus, S. mutans, and Bacteroides cereus. Results of in vitro release studies revealed that the effect was sustained over a period of 6 days and followed Fickian diffusion mechanism. In situ release study samples were well above the minimum inhibitory concentration of the drug. These samples were effective in inhibiting the growth of the above-mentioned strains. The optimized formulation was characterized for general appearance, content uniformity, and SEM. Stability studies carried out on the formulation showed the degradation rate constant value of 2.79 x 10(-4) per day. Retentive fibers were found to be very effective in controlled delivery of amoxycillin, and hence can be feasible alternative to systemic administration.

Amoxicillin↗

PubMed1990

[Properties and biological effect of dust of various artificial mineral fibers].

Developments and use of man-made mineral fibres are important for the progress in some technical fields. In the last years the number of man-made mineral fibres increased extraordinarily. For the medical evaluation it is necessary to determine the physico-chemical characteristics of the man-made mineral fibre dust and its biological effects in animal experiments. The results of the investigations are described.

Animals↗

PubMed1987

Initial junctions between developing parallel fibers and Purkinje cells are different from mature synaptic junctions.

During postnatal development of cerebellar cortex, junctions are formed between parallel fiber axons and the shafts of Purkinje cell dendrites. These shaft junctions resemble synaptic junctions on spines in thin sections, in that the axon contains a cluster of synaptic vesicles, and the pre- and postjunctional membranes are lined by electron-dense material. The shaft junctions do not have the aggregate of particles arrayed on the extracellular half of the postjunctional membrane that is characteristic of mature spine synaptic junctions in freeze-fractured preparations, however, and so presumably have a different protein composition. Shaft junctions are transient specializations, present only in developing tissue, but do not appear simply to be intermediates in the formation of mature spine synaptic junctions. In normal development, spines are formed by the Purkinje cell dendrite at sites not occupied by shaft junctions. Moreover, in certain neurological mutant mice, shaft junctions form in the absence of spine synapses, and in other systems spines develop in the absence of shaft junctions. We suggest that shaft junctions are a class of synapse formed during development which is distinguished by its capacity to dissociate, and that only some fraction of the parallel fibers forming shaft synapses with a developing Purkinje cell will have established spine synapses in the adult.

Aging↗

PubMed1974

Utilization of nucleoside diphosphate glucoses in developing cotton fibers.

The capacity for biosynthesis of hot alkali-insoluble products using uridine diphosphate (UDP)-glucose and guanosine diphosphate (GDP)-glucose as substrate has been studied in isolated cotton fibers harvested at various stages of development following anthesis. During the period of rapid elongation and primary wall synthesis (7-14 days postanthesis), incorporation of radioactivity from GDP-(14)C-glucose into hot alkali-insoluble product is high. This activity gradually declines and is not demonstrated in older fibers undergoing active deposition of secondary wall. With respect to all characteristics examined, the product from GDP-glucose resembles cellulose. Incorporation of UDP-(14)C-glucose into hot alkali-insoluble product was low in young fibers but increased to high levels in older fibers. This product was shown to be soluble in chloroform-methanol, and when chromatographed in lipid solvents it was separated into three components. Activity for the production of two of these three presumed glucolipids increased with increasing age of fibers.

Journal Article↗

PubMed1985

Slowing of neurofilament transport and the radial growth of developing nerve fibers.

Several lines of evidence indicate that neurofilaments are major intrinsic determinants of axonal caliber in myelinated nerve fibers, and that the delivery of neurofilaments by slow axonal transport is an important mechanism by which neurons regulate axonal caliber. To further clarify the relationship between neurofilament transport and axonal caliber, we examined transport in developing motor fibers of rat sciatic nerve. In 3-, 10-, 12-, and 20-week-old rats, lumbar motor neurons were labeled by the intraspinal injection of radioactive amino acids, and the distributions of labeled cytoskeletal proteins within the sciatic nerve were analyzed at various times afterwards using sodium dodecyl sulfate-polyacrylamide gel electrophoresis, gel fluorography, and liquid scintillation spectroscopy. There was a progressive decline in the velocity of neurofilament transport with increasing distance along axons undergoing radial growth. By examining transport in different regions of the nerve in animals of the same age, we separated age-dependent reductions in velocity from those related to position along the nerve. The cross-sectional areas of these motor axons (in the L5 ventral root) increased linearly between 3 and 18 weeks of age. Quantitative electron microscopic analysis at 3 and 10 weeks of age revealed that neurofilament density was comparable in fibers of all calibers, indicating that the radial growth of these myelinated nerve fibers correlates with a proportional increase in neurofilament content. We propose that progressive reduction in the velocity of neurofilament transport along the nerve provides for radial growth during development.

Amino Acids↗

PubMed1999

Wheat bran fiber and development of adenomatous polyps: evidence from randomized, controlled clinical trials.

Mutations in oncogenes and tumor suppressor genes are thought to initiate and promote the pathway to colorectal cancer, leading to hyperproliferation, the development of adenomas, and progression to gross malignancy. Intervention at any of these steps can potentially prevent the development of cancer. Several randomized, controlled trials have investigated the effect of dietary interventions, including the addition of wheat bran fiber, on the development of adenomatous polyps. In a familial adenomatous polyposis trial, patients were treated with 4 g of ascorbic acid plus 400 mg of alpha-tocopherol per day alone or with a grain fiber supplement (22.5 g/day) over a 4-year period. On an actual-intake basis, the combined intervention inhibited the development of rectal polyps. However, the Toronto Polyp Prevention Trial found no significant differences in polyp recurrence rates between patients who were counseled to follow a low-fat, high-fiber diet and patients consuming a typical Western diet with placebo fiber. A 9-month study of patients with resected colon adenomas found that dietary wheat bran fiber significantly reduced total, primary, and secondary fecal bile acid concentrations and excretion rates. Such bile acid levels are thought to be related to the risk of developing cancer. The Australian Polyp Prevention Project reported that the combination of fat reduction and a supplement of wheat bran reduced the incidence of large colorectal adenomas. These latter results suggest that intervention with a low-fat wheat bran supplemented diet inhibits the transition from smaller to larger adenomas, which may be a critical step in determining which adenomas progress to malignancy.

Adenomatous Polyposis Coli↗

PubMed1983

Changes in the distribution of the extrajunctional acetylcholine sensitivity along muscle fibers during development and following cordotomy in the rat.

Acetylcholine sensitivity along the entire length of muscle fibers was studied during postnatal development and following transection of the spinal cord in the rat. During postnatal development, the acetylcholine sensitivity in the soleus and extensor digitorum longus muscles decreased faster at the juxtajunctional region than near the tendons. Thus, the adult pattern of low acetylcholine sensitivity at the extrajunctional membrane was achieved through the uneven change of acetylcholine sensitivity during normal development. This uneven pattern of the sensitivity was found to appear in both muscles in older rats after cordotomy, and is in striking contrast to the uniform pattern in denervated muscles. The uneven appearance of the sensitivity could not be explained by changes in input resistance or resting membrane potential. In the soleus muscle whose nerve was implanted at an ectopic site, the lowest sensitivity also appeared at the ectopic juxtajunctional region after cordotomy. These results indicate that the motor nerve exerts regionally different effects along a fiber with respect to the appearance of acetylcholine receptors.

Acetylcholine↗

PubMed1995

Genes encoding small GTP-binding proteins analogous to mammalian rac are preferentially expressed in developing cotton fibers.

In animals, the small GTP-binding proteins, Rac and Rho, of the ras superfamily participate in the signal transduction pathway that regulates the organization of the actin cytoskeleton. We report here on the characterization of two distinct cDNA clones isolated from a cotton fiber cDNA library that code for homologs of animal Rac proteins. Using gene-specific probes, we have determined that amphidiploid cotton contains two genes that code for each of the two Rac proteins, designated Rac13 and Rac9, respectively. The gene for Rac13 shows highly enhanced expression in developing cotton fibers, with maximal expression occurring at the time of transition between primary and secondary wall synthesis. This is also the time at which reorganization of the cytoskeleton occurs, and thus the pattern of expression of Rac13 is consistent with its possible role, analogous to animal Rac, in the signal transduction pathway that controls cytoskeletal organization.

Amino Acid Sequence↗

PubMedDate not supplied

Fibrous connection to bone after immediate repair of the canine infraspinatus: the most effective bony surface for tendon attachment.

The purpose of this histologic study was to identify the most effective bony surface for fibrous connection to bone after immediate repair of the canine infraspinatus. Light microscopic views were used to evaluate collagen fiber development. The left infraspinatus tendon of 15 dogs was transected and repaired to 3 different bone surfaces: a tendon end adjacent to the tendon insertion (group 1, n = 5), a calcified fibrocartilage layer (group 2, n = 5), and a cancellous surface (group 3, n = 5). Tendon repair to distal tendon ends restored the 4-layered enthesis in the healing period, whereas tendon repair to the calcified fibrocartilage layer considerably delayed fiber development into bone. Fiber connection to cancellous surface developed according to the remodeling of trabecular bone. Secure fiber connection into the thickened trabecular bone developed by 16 postoperative weeks. On the basis of these results, in clinical settings, ruptured tendon ends should be attached to the remaining distal tendon end or to a cancellous surface; they should not be attached to a calcified fibrocartilage layer.

Animals↗

PubMed1991

Spatial association of renin-containing cells and nerve fibers in developing rat kidney.

The development of renin-containing cells and nerve fibers was studied in Sprague-Dawley rat kidneys during the last third of gestation and the first 15 days of postnatal life. Kidney tissue sections were stained for nerve fibers or double stained employing an anti-rat renin polyclonal antibody and a monoclonal antibody (TUJ1) directed against a neuron-specific class III beta-tubulin isotype. Renin-containing cells and nerve fibers were detected at 17 days of gestation, in close spatial relationship along the main branches of the renal artery. During fetal life, renin-containing cells and nerve fibers were spatially associated along arcuate and interlobular arteries, renin-containing cells being also present throughout the entire length of afferent arterioles supplying juxtamedullary glomeruli. During postnatal life the distribution of renin-containing cells progressively shifted to a restricted juxtaglomerular position in afferent arterioles. Simultaneously, density and organization of nerve fibers increased with age along the arterial vascular tree. Our results suggest that innervation of renin-containing cells is present in fetal life and follows the centrifugal pattern of renin distribution and nephrovascular development.

Animals↗

PubMed1967

Isometric tension differences in fibers of red and white muscles.

Measurements of maximum isometric tension and rate of onset of tension in fibers of glycerinated rat muscle indicate that the red soleus fibers develop significantly higher tensions than do white medial gastrocnemius fibers. Gastrocnemius fibers develop tension at a significantly faster rate than soleus fibers, however. These differences seem to be related to formation of actinmyosin cross-links.

Animals↗

PubMed1999

Uninjured C-fiber nociceptors develop spontaneous activity and alpha-adrenergic sensitivity following L6 spinal nerve ligation in monkey.

We investigated whether uninjured cutaneous C-fiber nociceptors in primates develop abnormal responses after partial denervation of the skin. Partial denervation was induced by tightly ligating spinal nerve L6 that innervates the dorsum of the foot. Using an in vitro skin-nerve preparation, we recorded from uninjured single afferent nerve fibers in the superficial peroneal nerve. Recordings were made from 32 C-fiber nociceptors 2-3 wk after ligation and from 29 C-fiber nociceptors in control animals. Phenylephrine, a selective alpha1-adrenergic agonist, and UK14304 (UK), a selective alpha2-adrenergic agonist, were applied to the receptive field for 5 min in increasing concentrations from 0.1 to 100 microM. Nociceptors from in vitro control experiments were not significantly different from nociceptors recorded by us previously in in vivo experiments. In comparison to in vitro control animals, the afferents found in lesioned animals had 1) a significantly higher incidence of spontaneous activity, 2) a significantly higher incidence of response to phenylephrine, and 3) a higher incidence of response to UK. In lesioned animals, the peak response to phenylephrine was significantly greater than to UK, and the mechanical threshold of phenylephrine-sensitive afferents was significantly lower than for phenylephrine-insensitive afferents. Staining with protein gene product 9.5 revealed an approximately 55% reduction in the number of unmyelinated terminals in the epidermis of the lesioned limb compared with the contralateral limb. Thus uninjured cutaneous C-fiber nociceptors that innervate skin partially denervated by ligation of a spinal nerve acquire two abnormal properties: spontaneous activity and alpha-adrenergic sensitivity. These abnormalities in nociceptor function may contribute to neuropathic pain.

Adrenergic alpha-Agonists↗

PubMed2005

Developmental and gene expression analyses of a cotton naked seed mutant.

Cotton fiber development is a fundamental biological phenomenon, yet the molecular basis of fiber cell initiation is poorly understood. We examined molecular and cellular events of fiber cell development in the naked seed mutant (N1N1) and its isogenic line of cotton (Gossypium hirsutum L. cv. Texas Marker-1, TM-1). The dominant mutation not only delayed the process of fiber cell formation and elongation but also reduced the total number of fiber cells, resulting in sparsely distributed short fibers. Gene expression changes in TM-1 and N1N1 mutant lines among four tissues were analyzed using spotted cotton oligo-gene microarrays. Using the Arabidopsis genes, we selected and designed approximately 1,334 70-mer oligos from a subset of cotton fiber ESTs. Statistical analysis of the microarray data indicates that the number of significantly differentially expressed genes was 856 in the leaves compared to the ovules (3 days post-anthesis, DPA), 632 in the petals relative to the ovules (3 DPA), and 91 in the ovules at 0 DPA compared to 3 DPA, all in TM-1. Moreover, 117 and 30 genes were expressed significantly different in the ovules at three and 0 DPA, respectively, between TM-1 and N1N1. Quantitative RT-PCR analysis of 23 fiber-associated genes in seven tissues including ovules, fiber-bearing ovules, fibers, and non-fiber tissues in TM-1 and N1N1 indicates a mode of temporal regulation of the genes involved in transcriptional and translational regulation, signal transduction, and cell differentiation during early stages of fiber development. Suppression of the fiber-associated genes in the mutant may suggest that the N1N1 mutation disrupts temporal regulation of gene expression, leading to a defective process of fiber cell elongation and development.

Arabidopsis↗

PubMed1988

Functional significance of myosin transitions in single fibers of developing soleus muscle.

The maximal velocity of shortening and myosin heavy chain (MHC) composition of single, chemically skinned fibers from neonatal and adult rat soleus muscles were examined to determine the relationship between these parameters during slow muscle development in the rat. In addition, the MHC composition of bundles of fibers from soleus muscles at the same ages was studied. The MHC compositions were examined using sodium dodecyl sulfate (SDS)-polyacrylamide gel electrophoresis. The results from the bundles of fibers indicate that from 3 days to 5 mo postnatal, the rat soleus contains predominantly MHCs that migrate in the vicinity of the MHC from adult slow muscle. From 14 days to 2 mo postnatal, there are also significant amounts of additional MHCs that comigrate on SDS gels with those characteristic of adult rat fast muscle. All the fibers studied at 3 and 7 days postnatal and at 5 mo and the majority of fibers from 14 days to 2 mo postnatal had relatively low shortening velocities. A few fibers from the latter group had significantly higher velocities. The faster fibers at each age had greater amounts of the MHCs that comigrate with the adult fast-type MHC on SDS gels. Thus the velocity of shortening of single fibers from the rat soleus muscle appears to be related to MHC composition during postnatal development.

Animals↗

PubMed2003

Effects of nicotine administration in developing muscle fibers of rats offspring.

The authors studied the effects of nicotine in developing skeletal muscles of rats. Pregnant Wistar rats received an enteral dose of nicotine (2.5, 5.0 or 10mg/kg, respectively, in groups G2, G5, and G10) from the 10th to the 18th or 20th days of pregnancy. Myotube atrophy was observed mainly in 20-day-old fetuses of G10. Twenty-day-old control fetus and of G2 and G5 had a high sarcoplasmic expression of desmin (weaker in G10). Vimentin expression was similar in 18-day-old fetuses of the control, G2, and G5 groups, but it was weaker in 20-day-old fetuses of the G2 and G5 groups. This would indicate an acceleration of the maturation pattern of vimentin expression in these intoxicated fetus. In conclusion, high doses of nicotine induce myotube atrophy and decrease of the expression of intermediate filaments, whereas relatively low doses of nicotine (G2 and G5) induce an early decrease of vimentin expression with no myofiber atrophy.

Animals↗

PubMed1997

Gonadotropin-releasing hormone containing neurons and olfactory fibers during development: from lamprey to mammals.

Gonadotropin releasing-hormone (GnRH) regulates the hypothalamo-pituitary-gonadal axis in all vertebrates. The vast majority of GnRH neurons are thought to be derived from progenitor cells in medial olfactory placodes. Several antibodies and lectins that recognize cell surface carbohydrates have been useful for delineating the migratory pathway from the olfactory placodes and vomeronasal organ, through the nasal compartment, and across the cribriform plate into the brain. In rats, alpha-galactosyl-linked glycoconjugates (immunoreactive with the CC2 monoclonal antibody) are expressed on fibers along the GnRH migration pathway and approximately 10% of the GnRH neuronal population. In lamprey, the alpha-galactosyl binding lectin, Grifonia simplicifolia-I (GS-1), identifies cells and fibers of the developing olfactory system. In contrast to the CC2 immunoreactive GnRH neurons in rats, the GS-1 does not label a subpopulation of presumptive GnRH neurons in lamprey. Results from these and other experiments suggest that GnRH neurons in developing lamprey do not originate within the olfactory placode, but rather within proliferative zones of the diencephalon. However, the overlap of olfactory- and GnRH-containing fibers from prolarval stages to metamorphosis, suggest that olfactory stimuli may play a major role in the regulation of GnRH secretion in lamprey throughout life. By contrast, olfactory fibers are directly relevant to the migration of GnRH neurons from the olfactory placodes in mammalian species. Primary interactions between olfactory fibers and GnRH neurons are likely transient in mammals, and so in later life olfactory modulation of GnRH secretion is likely to be indirect.

Aging↗

PubMed2000

Development of fiber optic and electrochemical pH sensors to monitor brain tissue.

This article describes fiber optic and electrochemical pH sensors that could become part of a therapeutic arsenal to quickly and aggressively treat stroke victims as well as people who have suffered brain trauma. The fiber optic sensor design was based on the immobilization of a pH-sensitive dye, seminaphthorhodamine-1 carboxylate (SNARF-1C), onto the end of a 125-microm-diameter silica optical fiber using the sol-gel method. A miniature bench-top fluorimeter system was developed for use with the optical fiber to obtain pH measurements. The electrochemical sensor was based on sputter-coated iridium oxide thin films. Linear and reproducible responses for both sensors were obtained in human blood with pH varying between 6.8 ato 8.0, which encompasses the clinically relevant range. In vivo studies were also performed and results indicated that both types of sensors tracked pH with very little drift.

Animals↗