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At least 163 records · Page 9Linked to original sources
PubMed2001

The experimental herbicide CGA 325'615 inhibits synthesis of crystalline cellulose and causes accumulation of non-crystalline beta-1,4-glucan associated with CesA protein.

Developing cotton (Gossypium hirsutum) fibers, cultured in vitro with their associated ovules, were used to compare the effects of two herbicides that inhibit cellulose synthesis: 2,6-dichlorobenzonitrile (DCB) and an experimental thiatriazine-based herbicide, CGA 325'615. CGA 325'615 in nanomolar concentrations or DCB in micromolar concentrations causes inhibition of synthesis of crystalline cellulose. Unlike DCB, CGA 325'615 also causes concomitant accumulation of non-crystalline beta-1,4-glucan that can be at least partially solubilized from fiber walls with ammonium oxalate. The unusual solubility of this accumulated glucan may be explained by its strong association with protein. Treatment of the glucan fraction with protease changes its size distribution and leads to precipitation of the glucan. Treatment of the glucan fraction with cellulase digests the glucan and also releases protein that has been characterized as GhCesA-1 and GhCesA-2--proteins that are believed to represent the catalytic subunit of cellulose synthase. The fact that cellulase treatment is required to release this protein indicates an extremely tight association of the glucan with the CesA proteins. In addition, CGA 325'615, but not DCB, also causes accumulation of CesA protein and a membrane-associated cellulase in the membrane fraction of fibers. In addition to the effects of CGA 325'615 on levels of both of these proteins, the level of both also shows coordinate regulation during fiber development, further suggesting they are both important for cellulose synthesis. The accumulation of non-crystalline glucan caused by CGA 325'615 mimics the phenotype of the cellulose-deficient rsw1 mutant of Arabidopsis that also accumulates an apparently similar glucan (T. Arioli, L. Peng, A.S. Betzner, J. Burn, W. Wittke, W. Herth, C. Camilleri, H. Hofte, J. Plazinski, R. Birch et al. [1998] Science 279: 717).

Amino Acid Sequence↗
PubMed1977

UDP-glucose: Glucan Synthetase in Developing Cotton Fibers: II. Structure of the Reaction Product.

The solubility properties, composition, and structure of the radioactive product synthesized from UDP-[(14)C]glucose by a highly active cotton fiber glucan synthetase have been determined. Product obtained under the following three different conditions was analyzed: at high and low substrate concentrations by detached fibers, and at high substrate concentrations with an isolated particulate preparation. The results of acetic and nitric acid digestion, enzyme digestion, total acid hydrolyses, periodate oxidation, partial acid hydrolyses, and methylation analyses all support the conclusion that the product of the glucan synthetase produced under all three assay conditions is a linear beta-(1-->3)-glucan.

Journal Article↗
PubMedDate not supplied

[Development of fiber endoscopes and some aspects of gastrointestinal endoscopy].

Clinical evaluation of the up-to-date fibre endoscope models makes it possible to set apart 3 successive stages in the course of creating gastro-intestinal endoscopy, viz. construction of instruments with side optics, making esophagofibroscopes with end optics and transformation of esophagofibroscopes into panendoscopes. Depending upon the nature of the disease and the diagnostic objectives to be fulfilled various types of fibre endoscopes, both new and old, are recommended for clinical use.

Biomedical Engineering↗
PubMed1976

[A functional-morphologic analysis of reactive changes in nerve fibers during development of collateral circulation in nerves].

After stopping the blood circulation along the femoral artery the collateral blood circulation is developing unevenly in different nerves. It depends on the architectonics of blood vessels of the zone. In time the intravenous anastomosis in the distal part of the ischiatic nerve sharply increases. It is pulsing and compressing the nerve bundles and may have a negative influence on nerve fibres. Reactive morphological changes of the axis cylinder, myelin incisions and Ranvier's constrictions are found in such a nerve. The analysis has shown that the changes noted have a character of local non-specific process accompanying physiological manifestations of parabiosis.

Animals↗
PubMed1990

Pulmonary elastic fibers in normal human development and in pathological conditions.

Normal human pulmonary elastic fiber development and development in some pathological conditions were examined using elastic stains by light microscopy, electron microscopy, and immunohistochemistry. In normal development elastic fibers, composed mainly of microfibrils, first appeared around primitive bronchioles at 10 weeks of gestation. As they matured, their appearance became more amorphous, and they extended into the peripheral alveolar walls. Development of elastic fibers was retarded in the hypoplastic lungs of the oligohydramnios syndrome, diaphragmatic hernia, and hydrops fetalis. Elastic development was also retarded in congenital pulmonary lymphangiectasia and in focal areas of lungs with pulmonary dysplasia. Distribution of well-developed elastic fibers was found around the dilated bronchioles and alveoli in cases of congenital cystic adenomatoid malformation and extralobar pulmonary sequestration. Elastic fibers were distributed irregularly and unevenly in the lungs of bronchopulmonary dysplasia and ventilated cases of Wilson Mikity syndrome. In addition, four very immature infants who had progressively deteriorating respiratory function showed an almost total lack of elastic fibers in their alveolar walls.

Chronic Disease↗
PubMed1989

Regional distribution of fiber types in developing baboon diaphragm muscles.

Fiber type distribution and mean fiber area were determined for seven sites in diaphragm muscles of premature (140 days gestation), full-term (180 days gestation), and adult baboons. Within a group, data did not differ significantly amongst the seven sites. The diaphragm of premature animals had a large proportion [56(+/- 2)%] of type IIc fibers, smaller proportions of type I, IIo, and IIh fibers [16(+/- 2), 21(+/- 1), and 7(+/- 2)%, respectively], and no type IIg fibers. Full-term animals had fewer type IIc [2(+/- 1)%] fibers, greater proportions of type I [46(+/- 2)%], IIh [23(+/- 1)%], and IIg [11(+/- 1)%] fibers, and a similar proportion of type IIo fibers [17(+/- 1)%]. Diaphragm from adult baboons had similar proportions of type IIh, IIg, and IIc fibers in females [39(+/- 4), 20(+/- 2), 1(+/- 1), 41(+/- 5), and 1(+/- 1)%] and males [48(+/- 2), 16 (+/- 1), 0(+/- 0), 36(+/- 2), and 3(+/- 2)%]. Fiber area for premature [143(+/- 9), 210(+/- 15), 231(+/- 15), and 156(+/- 16) microns2 for type I, IIo, IIh, and IIc fibers], newborn [317(+/- 32), 374(+/- 36), 468(+/- 42), 498(+/- 43), and 322(+/- 37) microns2 for type I, IIo, IIh, IIg, and IIc fibers], and for type I, IIo, IIg, and IIc fibers from adult female [1,759(+/- 130), 2,365(+/- 284), 5,026(+/- 742), and 1,843(+/- 111) microns2] and adult male [2,513(+/- 221), 3,987(+/- 267), 6,102(+/- 376), and 2,833(+/- 151) microns2] baboons indicated growth which correlated with body weight. Our results also show that metabolic and contractile enzymes develop normally, but growth of respiratory muscle fibers is arrested, during 10 days following premature birth.

Animals↗
PubMed1993

NCAM immunoreactivity on mossy fibers and reactive astrocytes in the hippocampus of epileptic rats.

Sprouting and synaptogenesis of mossy fibers develop in adult hippocampus after epilepsy. In control conditions, mossy fibers constitute the main afferent pathway to the Ammon's horn, where they mainly innervate CA3 pyramidal cells, but after treatment with the convulsant agent, kainate, mossy fibers also innervate granule cell dendrites generating recurrent excitatory circuits which may contribute to the maintenance of the epileptic condition. In the present study we show an enhanced immunoreactivity to neural cell adhesion molecules (NCAMs), a family of membrane glycoproteins involved in axonal growth. NCAM immunoreactivity is enriched on cytoplasmic membranes of axon shafts that are likely to be mossy fiber collaterals. NCAM immunoreactivity was also observed on the cytoplasmic membranes of reactive astrocytes, at the axon-glial contacts. Our results therefore suggest that there is an interaction of newly developed mossy fibers with other fibers and glial cells. This interaction may be mediated by NCAMs. Taking into account the trophic properties of NCAMs we suggest that they regulate the sprouting, growing and synaptogenesis of mossy fibers in epileptic conditions.

Afferent Pathways↗
PubMed1974

Oxytalan connective tissue fibers: a review.

Oxytalan connective tissue fibers are a separate and distinct fiber type. Although current histochemical methods cannot distinguish pre-elastic from oxytalan fibers, the two fiber types are readily distinguished by electron microscopy. Oxytalan fibers are found in periodontal membranes of all teeth of man, monkeys, rats, guinea pigs and mice. Increased numbers and size of oxytalan fibers are observed in periodontal membranes of teeth subjected to increased stress, such as those used for bridge abutments. Edwards (1968) observed increased size and number of oxytalan fibers in periodontal membranes of dog incisors subjected to orthodontic forces. Some oxytalan fibers serve to support the blood and lymphatic vessels leading to the teeth. Oxytalan fibers appear to have a protein component and a stainable component digestible with beta-glucuronidase after peracetic acid digestion. Oxytalan fibers develop in repair tissues of the periodontal membrane. Although oxytalan fibers probably develop in relation to tumors developed from dental tissues, electron microscopy must be employed to distinguish oxytalan from developing elastic tissues inasmuch as histochemical methods are inadequate.

Adolescent↗
PubMed1994

Single-fiber study of contractile and biochemical properties of skeletal muscles in streptozotocin-induced diabetic rats.

Mechanically skinned, single muscle fibers, isometrically activated in pH and Ca2+ (Sr2+) buffered solutions were used to examine the function of the contractile apparatus in slow- and fast-twitch fibers from soleus (SOL, predominantly slow-twitch) and extensor digitorum longus (EDL, predominantly fast-twitch) muscles of streptozotocin (STZ)-induced diabetic rats and age-matched controls. Three and 14 days after STZ administration, the contractile properties of muscle fibers from diabetic rats did not differ significantly from those of controls with respect to several mechanical parameters, such as maximum Ca-activated tension, activation threshold, and sensitivity to Ca2+ and Sr2+. In contrast, 28 days after STZ administration, 37.5% of the fast-twitch EDL fibers developed maximum activated tensions (77.1 +/- 10.4 kN/m2), which were significantly lower than those developed by controls (244.0 +/- 14.3 kN/m2), and the slow-twitch SOL fibers displayed a significantly higher sensitivity to Ca2+ (and Sr2+) than the controls. All fibers from diabetic rats, including the low-tension EDL fibers and higher Ca sensitivity SOL fibers displayed control-like electrophoretic profiles of the major myofibrillar proteins. Taken together with data from earlier studies on the effects of long-term diabetes on whole skeletal muscle contractility, these results strongly suggest that 1) the decrease in tetanic tension output of EDL muscles induced by diabetes is caused mainly by direct effects of the diabetic condition on the contractile/regulatory system of a subpopulation of fast-twitch fibers, which develop little force, and 2) the diabetes-induced slowing of twitch times of SOL muscles is caused in part by the increased sensitivity to Ca2+ of the contractile apparatus in the slow-twitch fibers.

Analysis of Variance↗
PubMed1991

Origin of the ring muscle fibers in neuromuscular diseases.

Morphological histochemical and ultrastructural examination of the ring fibers in one case of myotonic dystrophy and one case of mitochondrial myopathy provides evidence that the ring fibers develop in the course of fiber splitting and reinnervation of muscle fiber fragments. The reinnervation may have been due to a neurogenic lesion coexisting in both cases with the myopathic picture. The histologically different type of annular myofibrils observed in one case of cap disease is probably due to delayed embryonic development and abnormal relations between the myofibrils and elements of the cytoskeleton.

Adenosine Triphosphatases↗
PubMed1976

Postnatal cytochemical development of muscle fibers in segmental tail muscles of the rat.

Postnatal development of extrafusal and intrafusal muscle fibers was examined histochemically in segmental tail muscles of the rat. At birth all fibers show a strong reaction for myosin ATPase, uniformity in diameter, and homogeneity in staining intensity. During the first postnatal week, the muscle fibers undergo gradual hypertrophy and hyperplasia but they all maintain the same intense homogeneous staining pattern for the enzyme. By day 9, further differentiation of the muscle fibers results in the formation of a second intrafusal fiber type while the extrafusal fibers are still relatively homogeneous. Finally, two kinds of extrafusal fiber and a third type of intrafusal fiber can be distinguished by day 21. This histochemical fiber pattern is essentially maintained in the adult. These findings show that fiber type development in rat tail muscles lags behind the usual time course of myogenesis known to occur in more rostral regions of the animal. It also indicates that histochemical differentiation of intrafusal fibers in these muscles does not parallel that which occurs in extrafusal fibers. It is likely that arrival and initial contact of sensory nerve terminals on developing intrafusal fibers at day 7 directly influences their relatively early histochemical heterogeneity.

Adenosine Triphosphatases↗
PubMed1992

[Guiding effect of embryonic fimbria graft on cholinergic fiber growth in hippocampus of adult rats].

In view of the fact that in embryonic and neonatal central nervous system (CNS), the pathway of developing fiber tracts is capable of guiding the axonal growth, it would be interesting to know whether a similar effect exists on the axonal growth in adult CNS. Embryonic fimbria was grafted into the hippocampus of the adult rat. Two weeks later, the grafts were examined for cholinergic fibers with AChE histochemical method. It was found that a lot of cholinergic fibers appeared in the embryonic graft, but none of them in the adult fimbria graft as control. If the fimbria-fornix was transected at the time of grafting, no cholinergic fibers could subsequently be detected in both the embryonic graft and the host hippocampus. If a suspension of embryonic fimbria was used as a graft, only a few of long cholinergic fibers could be found in the grafted area. However, if tissue fragments of embryonic fimbria adhered to a strip of nitrocellulose filter were grafted as previously, numerous cholinergic fibers from the host hippocampus were found to be attracted around the strip and grow along the surface of the filter. The results seem to indicate that grafted embryonic fimbria or its tissue fragments are able to guide cholinergic fiber growth in adult hippocampus. It is possible that embryonic fimbria and other pathways of developing CNS fiber tracts provide a natural substrate for guiding axonal growth in adult CNS.

Acetylcholine↗