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PubMed2004

Structural and functional rearrangement of muscle spindles in rats under conditions or zero gravity.

Electron microscopy of muscle spindles in m. extensor halucis longus of rats 14 days after space mission on board SLS-2 space laboratory (USA) showed structural rearrangement in the receptors. The number of intrafusal fibers increased, but some fibers developed degenerative changes. The changes were also seen in the spindle capsule, but its integrity was not impaired. Vascularization of the spindle capsule was impaired as a result of necrobiotic changes in capillary endotheliocytes. Sensory nerve endings were the most sensitive structures of the receptor. Destructive changes in various structures of the muscle spindles were paralleled by regenerative processes.

Animals↗

PubMed1999

The pathogenesis of familial hypertrophic cardiomyopathy: early and evolving effects from an alpha-cardiac myosin heavy chain missense mutation.

Familial hypertrophic cardiomyopathy (FHC) is a genetic disorder resulting from mutations in genes encoding sarcomeric proteins. This typically induces hyperdynamic ejection, impaired relaxation, delayed early filling, myocyte disarray and fibrosis, and increased chamber end-systolic stiffness. To better understand the disease pathogenesis, early (primary) abnormalities must be distinguished from evolving responses to the genetic defect. We did in vivo analysis using a mouse model of FHC with an Arg403Gln alpha-cardiac myosin heavy chain missense mutation, and used newly developed methods for assessing in situ pressure-volume relations. Hearts of young mutant mice (6 weeks old), which show no chamber morphologic or gross histologic abnormalities, had altered contraction kinetics, with considerably delayed pressure relaxation and chamber filling, yet accelerated systolic pressure rise. Older mutant mice (20 weeks old), which develop fiber disarray and fibrosis, had diastolic and systolic kinetic changes similar to if not slightly less than those of younger mice. However, the hearts of older mutant mice also showed hyperdynamic contraction, with increased end-systolic chamber stiffness, outflow tract pressure gradients and a lower cardiac index due to reduced chamber filling; all 'hallmarks' of human disease. These data provide new insights into the temporal evolution of FHC. Such data may help direct new therapeutic strategies to diminish disease progression.

Aging↗

PubMed2000

The most unkindest cut of all: on the multiple roles of mammalian caspases.

The caspases, first discovered almost a decade ago, are intracellular cysteine proteases which have been shown to play an essential role in the initiation and execution phases of apoptotic cell death. Numerous strategies for the activation and inhibition of these 'killer' proteases have evolved, including the regulation of caspase expression and function at the transcriptional and post-translational level, as well as the expression of viral and cellular inhibitors of caspases. Emerging evidence in recent years has also implicated the caspases in various, nonapoptotic aspects of cellular physiology, such as cytokine processing during inflammation, differentiation of progenitor cells during erythropoiesis and lens fiber development, and proliferation of T lymphocytes, thus attesting to the pleiotropic functions of these proteases. The present review aims to discuss the multiple roles of the mammalian caspases with particular emphasis on their activation and regulation in cells of leukemic origin and the attendant possibilities of therapeutic intervention.

Animals↗

PubMed1984

Tunicamycin blocks neuritogenesis and glucosamine labeling of gangliosides in developing cerebral neuron cultures.

Fetal cerebral neurons at the initiation of active neurite outgrowth in culture incorporate 4-fold more [3H]glucosamine into glycoproteins than into the cellular lipid fraction. After 8 days or longer, when a well-developed fiber network is apparent, lipids are labeled more extensively than the glycoproteins. Labeling of the latter is inhibited 95% and 89% by 0.5 microgram of tunicamycin per ml added to 1-day-old and 8-day-old cultures, respectively. Labeling of glycolipids is inhibited 30% in 1-day-old and 86% in 8-day-old cultures. Tunicamycin blocks incorporation of glucosamine label into practically all ganglioside species except for a resorcinol-positive, sialidase-sensitive band tentatively identified as GQ1b tetrasialoganglioside (Svennerholm ganglioside nomenclature). It also substantially reduces binding of 125I-labeled tetanus toxin to intact cells. There is 14% and 27% reduction in the total ganglioside sialic acid content in 1-day-old and 8-day-old cells treated for 24 hr with 0.5 microgram of tunicamycin per ml, but no substantial compositional changes are encountered. Tunicamycin blocks neurite outgrowth when added to cells soon after plating but causes no retraction or losses of fibers once the fiber network is established. Therefore, inhibition of neurite outgrowth by tunicamycin is not due to an effect on cellular gangliosides but can be correlated to an inhibition of protein glycosylation.

Animals↗

PubMed1996

NG2 proteoglycan and the actin-binding protein fascin define separate populations of actin-containing filopodia and lamellipodia during cell spreading and migration.

The transmembrane proteoglycan NG2 is able to interact both with components of the extracellular matrix and with the actin cytoskeleton. An examination of the distribution of NG2 during cell spreading suggests that NG2 can associate with two distinct types of actin-containing cytoskeletal structures, depending on the nature of the stimulus derived from the substratum. On fibronectin-coated dishes, cell surface NG2 associates exclusively with stress fibers developing within the cell. On poly-L-lysine-coated dishes, cell surface NG2 is associated with radial processes extending from the cell periphery. Spreading on fibronectin/poly-L-lysine mixtures, as well as on matrix components such as laminin, tenascin, and type VI collagen, produces cells with mosaic characteristics, i.e., NG2 is associated with both types of structures. NG2-positive radial processes are distinct from a second population of radial structures that contain fascin. NG2-positive extensions appear to be individual self-contained units (filopodia), whereas fascin is associated with actin ribs within sheets of membrane (lamellipodia). NG2- and fascin-positive structures are often localized to opposite poles of spreading cells, suggesting a possible role for the two classes of cellular extensions in the establishment of cell polarity during morphogenesis or migration. Time lapse imaging confirms the presence of lamellipodia on the leading edges of migrating cells, while numerous filopodia are present on trailing edges.

Actins↗

PubMed1998

Localization of LewisX, sialyl-LewisX and alpha-galactosyl epitopes on glycosphingolipids in lens tissues.

Mammalian lens contains several neutral and acidic glycosphingolipids, the core structures of which are ganglio-, neolacto-, globo-, and isoglobo-series sugar chains. Old World monkey lens shows glycosphingolipid compositions similar to those of human cataractous lens, in particular the presence of Lewisxand sialyl-Lewisxepitopes and the absence of alpha-galactosyl epitope. Dog and pig lenses contain globotriaosylceramide and the sialyl-Lewisxcontaining neolactotetraosylceramide, respectively, which were found in primate lens, together with the alpha-galactosyl epitope containing neolactotetraosylceramide. Thin-layer chromatography immunostaining revealed the enrichment of some neolacto-series glycosphingolipids in the cortical and nuclear fibers, but not in lens epithelia, of dog, pig, and Japanese monkey lenses. Immunohistochemical studies confirmed the expression of Lewisx, sialyl-Lewisx, and alpha-galactosyl epitopes in the inner cortical and nuclear fibers, in association with the differentiation and maturation of lens epithelial cells to lens fibers. Glycobiological approaches thus suggested that some neolacto-series glycosphingolipids are involved in lens fiber development, in which the physiological roles of the alpha-galactosyl epitope are evolutionarily replaced by the Lewisxand sialyl-Lewisxepitopes in Old World monkeys and humans.

Animals↗

PubMed2000

Early posthatch starvation decreases satellite cell proliferation and skeletal muscle growth in chicks.

The effect of posthatch starvation on skeletal muscle growth and satellite cell proliferation was examined in chicks. Chicks were either fed or starved for 48 h posthatch (d 0-d 2, d 2-d 4 or d 4-d 6) and then refed for 41 d. Body and breast muscle weights were significantly lower in starved chicks than in fed controls throughout the experiment. Histochemical staining revealed that skeletal muscle fiber development in the starved group lagged behind that of the fed group. Starvation from d 2 to 4 and d 4 to 6 posthatch had a progressively lesser effect than did immediate posthatch starvation (P < 0.05). In vitro culturing of breast muscle satellite cells revealed that DNA synthesis and number of cells per gram of muscle in the fed chicks peaked on d 2 and d 3, and then declined. In contrast, DNA synthesis in the cells of starved chicks declined on d 2 and increased on d 3 when chicks were refed. A similar pattern was seen for the number of cells per gram muscle; however, in general cell numbers tended to be higher in the starved group than in controls (P < 0.1). The results obtained with cultured cells were parallel with in situ immunostaining with 5-bromo-2'-deoxyuridine and proliferating cell nuclear antigen in breast muscle from experimental chicks, and with growth hormone receptor expression. These results suggest that satellite cell cultures are a reliable tool for evaluating muscle growth in postnatal chickens. We conclude that sufficient feed in the immediate postnatal period is critical for satellite cell proliferation and skeletal muscle development and is thus important for optimal muscle growth.

Aging↗

PubMed1997

High-resolution physical and transcriptional mapping of the autoimmune polyendocrinopathy-candidiasis-ectodermal dystrophy locus on chromosome 21q22.3 by FISH.

Autoimmune-polyendocrinopathy-candidiasis-ectodermal dystrophy (APECED, PGD type I) is an autosomal recessive disease enriched in the Finnish population. Previously, we have assigned APECED to a 2.6-cM interval on chromosome 21q22.3 by linkage analysis in 14 Finnish families. This subtelomeric region of 21q22.3 seems to have sequence features resulting in its under-representation in large insert genomic libraries, and only a few large insert clones have been available for positional cloning to date. Here, we report the refined localization of the APECED gene and a visual physical map of 800 kb covering the critical chromosomal region for the gene. In the construction of the physical map, the recently developed fiber FISH techniques were essential for the orientation of the cosmid PI, PAC, and BAC clones in relation to each other. We also localized two cDNAs within this genomic region by fiber FISH combined with the highly sensitive tyramide-based detection method. These data will facilitate the final cloning of the APECED gene and any other novel gene in this complex genomic region.

Chromosome Mapping↗

PubMed1986

Morphogenesis of septa in hepatic fibrosis induced by choline deficiency in rats. Correlation between ito cells, pericellular fibrosis, and septa.

Examination of hepatic fibrosis induced by choline deficient diet showed the histogenesis of early fibrosis and septa formation. Male rats were fed a choline deficient diet. Groups of three were sacrificed after 1, 2, 3, 6, 8, 12, and 13 weeks. Control groups of three rats were sacrificed after 6, 8, and 12 weeks. All choline deficient rats showed initial steatosis around the portal tracts. The fat droplets were small at first and gave a microvesicular appearance. As they grew, they gathered around the terminal hepatic venule by the 3rd week. Then, reticular fibers developed around the hepatocytes in the centrolobular area and fibroses connected the terminal hepatic venules. The fat droplets became larger and made nodular masses around the portal tract. These compressed the fibroses to the periphery where they formed septa. After 12 weeks, regenerating nodules developed. Electron microscopy showed that fat storing cells helped cause pericellular fibrosis.

Animals↗

PubMed2006

Bone morphogenetic protein down-regulation of neuronal pituitary adenylate cyclase-activating polypeptide and reciprocal effects on vasoactive intestinal peptide expression.

Among bone morphogenetic proteins (BMPs), the decapentaplegic (Dpp; BMP2, BMP4) and glass bottom boat (Gbb/60A; BMP5, BMP6, BMP7) subgroups have well-described functions guiding autonomic and sensory neuronal development, fiber formation and neurophenotypic identities. Evaluation of rat superior cervical ganglia (SCG) post-ganglionic sympathetic neuron developmental regulators identified that selected BMPs of the transforming growth factor beta superfamily have reciprocal effects on neuronal pituitary adenylate cyclase-activating polypeptide (PACAP) and vasoactive intestinal peptide (VIP) expression. Dpp and Gbb/60A BMPs rapidly down-regulated PACAP expression, while up-regulating other sympathetic neuropeptides, including PACAP-related VIP. The suppressive effects of BMP on PACAP mRNA and peptide expression were potent, efficacious and phosphorylated mothers against decapentaplegic homolog (Smad) signaling-dependent. Axotomy of SCG dramatically increases PACAP expression, and the possibility that abrogation of inhibitory retrograde target tissue BMP signaling may contribute to this up-regulation of sympathetic neuron PACAP was investigated. Replacement of BMP6 to SCG explant preparations significantly blunted the injury-induced elevated PACAP expression, with a concomitant decrease in sympathetic PACAP-immunoreactive neuron numbers. These studies suggested that BMPs modulate neuropeptide identity and diversity by stimulating or restricting the expression of specific peptidergic systems. Furthermore, the liberation of SCG neurons from target-derived BMP inhibition following axotomy may be one participating mechanism associated with injury-induced neuropeptidergic plasticity.

Animals↗

PubMed1972

Length-force relation of calcium activated muscle fibers.

Calcium activated skinned frog muscle fibers develop a large relative force at a sarcomere length of 1.0 micrometer. Since the normal myofilament lattice is perturbed at this length, regularity of the lattice does not appear to be an important factor in the contraction mechanism.

Animals↗

PubMed1986

Vasoactive agents affect mesangial cell adhesion.

The formation and maintenance of stress fibers in cultured mesangial cells is associated with myosin light chain phosphorylation [Kreisberg et al. Am. J. Physiol. 249 (Renal Fluid Electrolyte Physiol. 18): F227-F235, 1985], a biochemical indicator for activation of actin-myosin interactions. Agents that elevate intracellular levels of adenosine 3',5'-cyclic monophosphate (cAMP) (e.g., isoproterenol) fragment stress fibers and cause myosin light chain dephosphorylation, whereas the addition of contractile agents such as arginine vasopressin (AVP) and prostaglandin E2 (PGE2) reverses these changes. Because stress fiber development in cultured cells is correlated with tight cell to substrate adhesion, we wanted to examine whether vasoactive agents have an effect on mesangial cell adhesion. Both isoproterenol and dibutyryl cAMP (DBcAMP) reduced mesangial cell adherence as measured by a trypsin assay (% detached cells: control 11 +/- 2.4%; isoproterenol plus isobutylmethylxanthine (IBMX) = 48.3 +/- 7.4%; DBcAMP = 29.3 +/- 3.7%; DBcAMP-IBMX = 73 +/- 4.4%). The areas of focal (adhesive) contacts between the cell and substratum as observed by interference-reflexion microscopy were also reduced, being replaced by areas of greater separation (% of the surface in contact with the substratum: control = 7.4 +/- 0.8%; isoproterenol-IBMX = 2.9 +/- 1.1%). Addition of PGE2 or AVP to the incubation medium containing the cAMP-elevating agents prevented the above changes. PGE2 or AVP alone increased mesangial cell adhesion (% detached cells: control 11 +/- 2.4%; PGE2 = 6.8 +/- 0.5%; AVP = 5.1 +/- 1.2%).(ABSTRACT TRUNCATED AT 250 WORDS)

1-Methyl-3-isobutylxanthine↗

PubMed1990

Evidence for increased myofilament Ca2+ sensitivity in norepinephrine-activated vascular smooth muscle.

The agonist-induced change in Ca2+ sensitivity of smooth muscle myofilaments was investigated in intact and permeabilized vascular preparations isolated from the rat and the rabbit. In intact rat mesenteric artery, membrane depolarization by 80 mM K+ solution or alpha-adrenergic stimulation by norepinephrine (NE) increased tension monotonically with increasing extracellular Ca2+ concentration ([Ca2+]e). The [Ca2+]e-tension curve generated during activation by NE was located to the left of that during activation by high K+. The protein kinase C (PKC) activator 12-O-tetradecanoylphorbol-13-acetate (TPA) shifted the high K+ [Ca2+]e-tension curve to the left but did not affect the NE curve. In rat mesenteric artery permeabilized by alpha-toxin, tension was measured while the intracellular free Ca2+ concentration ([Ca2+]i) was controlled using 2 mM ethylene glycol-bis(beta-aminoethyl ether)-N,N,N'N'-tetraacetic acid and Ca2+ buffer solutions. The alpha-toxin-permeabilized fibers developed tension as a function of Ca2+ concentration. TPA and guanosine 5'-[gamma-thio]triphosphate (GTP gamma S, a nonhydrolyzable GTP analogue) significantly shifted the pCa-tension curve to the left. In intact rabbit inferior vena cava, tension was recorded simultaneously with [Ca2+]i as measured by fura-2. TPA caused a gradual increase in tension without change in [Ca2+]i. In rabbit mesenteric artery permeabilized by alpha-toxin, the tissue still responded to NE, indicating that alpha-adrenergic receptors remained intact. The response to NE was augmented by GTP and inhibited by guanosine 5'-[beta-thio]diphosphate (GDP beta S, a nonhydrolyzable GDP analogue) suggesting that a G protein is coupled with the alpha-adrenergic receptor.(ABSTRACT TRUNCATED AT 250 WORDS)

Actin Cytoskeleton↗

PubMed1991

Changes in cytochrome oxidation in outer and inner stripes of outer medulla.

To examine regional cytochrome oxidation in the outer medulla, we developed fiber optic probes that allowed us to obtain localized reflectance measurements from the outer and inner stripes of the outer medulla. We measured directional changes in cytochrome oxidation in these two regions. In the outer stripe furosemide surprisingly caused a significant decrease in cytochrome oxidation. The decrease occurred concomitantly with a fall in outer medullary blood flow as measured by laser-Doppler flowmetry. Saralasin, an antagonist of angiotensin II caused a significant increase in cytochrome oxidation in the outer stripe. In the inner stripe furosemide tended to increase cytochrome oxidation, and saralasin had no effect. These results indicate that the two regions of the outer medulla may be affected differently by the same agent. They suggest that cytochrome oxidation in the outer stripe is predominantly influenced by outer medullary blood flow, whereas the inner stripe is predominantly influenced by the rate of oxygen consumption. The advantages and limitations of this methodology are discussed.

Animals↗

PubMed1986

Fatal metabolic acidosis, hyperglycemia, and coma after steroid therapy for Kearns-Sayre syndrome.

Two adolescent boys with Kearns-Sayre syndrome (progressive external ophthalmoplegia, heart block, elevated CSF protein, and ragged-red muscle fibers) developed lethargy, increasing somnolence, polydipsia, polyphagia, and polyuria after a brief course of steroid therapy. Both had hyperglycemia and acidosis. Nonketotic, lactic acidosis was present in one and ketosis in the other. Severe respiratory failure developed, and both patients died. Postmortem revealed fatty infiltration of the pancreas in addition to a diffuse spongiform encephalopathy.

Acidosis↗

PubMed2006

Low-cost wavelength measurement based on a macrobending single-mode fiber.

A low-cost all-fiber wavelength measurement technique is proposed and demonstrated. A macrobending standard single-mode fiber is developed as an edge filter with an optimal design and simple surface processing. A ratiometric wavelength measurement system employing the developed macrobending fiber filter demonstrates a resolution of approximately 10 pm in a wavelength range from 1,500 to 1,560 nm with ease of assembly and calibration.

Journal Article↗

PubMedDate not supplied

Changes in phenylalanine ammonia-lyase activity and gene expression during storage of asparagus spears.

A cDNA clone coding phenylalanine ammonia-lyase (PAL) was isolated from a cDNA library prepared from asparagus spears (Asparagus officinalis L. cv. Welcome) using the reverse transcription-polymerase chain reaction (RT-PCR). The partial cDNA clone encoded an mRNA of 527 bp and the derived amino acid sequence was found highly homologous to PAL from rice, maize and barley. Northern blot analysis showed an increase of pAS-PAL mRNA until 24 h at 20 degrees C, which coincided well with PAL activity and fiber development, suggesting that the increase is a response to the wounding associated with harvest.

Amino Acid Sequence↗

PubMed1975

Biochemical study of fibrosis in the rat liver in biliary obstruction.

In an attempt to study the collagen formation in the liver occurring in association with obstructive jaundice, the authors carried out an experiment with liver slices from common bile duct-ligated rats. Hepatic collagen was fractionated into the neutral soluble, acid soluble and insoluble fractions, and the hydroxyproline synthesis rate of each fraction was measured using 14C-proline. Determination was also made for hexosamine content in the same liver tissue. The hydroxyproline content of hepatic collagen increased as biliary obstruction was prolonged, particularly from the 4th week, which is the transitional period of liver histology into biliary cirrhosis. The hexosamine content of hepatic collagen showed a similar tendency. The neutral soluble, acid soluble and insoluble collagen fractions all increased as biliary obstruction was prolonged. The collagenosynthetic activity of the neutral soluble fraction, attained a peak in 1 to 2 weeks of biliary obstruction, which indicates that collagen fibers are formed actively in the early stage of jaundice, although there is only a slight increase in the absolute amount of fibers developed then. Serum monoamine oxidase level tended to be parallel to collagenosynthetic activity but not to collagen content.

Animals↗