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Biomedical subjects

D A Riley

Publications and source records attributed to D A Riley.

At least 55 records · Page 3Linked to original sources
PubMed1991

Histochemical staining of nerve endings as an aid to free muscle transplantation.

Histochemical staining techniques that identify intact motor nerve fascicles are available to aid free muscle transplantation. Cholinesterase activity of myelinated axons can be identified by Karnovsky and Roots's technique. Axon viability can be assessed based on the presence of axoplasmic enzyme activity. By reacting serial sections for cholinesterase activity and carbonic anhydrase activity, which labels sensory axons, an accurate cross-sectional map of regenerating or functional sensory and motor nerve fibers can be constructed. Resolving the motor and sensory identities of fascicles in a mixed peripheral nerve should lead to more precise coaptation of recipient motor fibers to the motor nerve of the transferred muscle and enhance reinnervation.

Adult↗
PubMed1991

Carbonic anhydrase in turtle bladder mitochondrial-rich luminal and subluminal cells.

Bladders from March-April turtles were processed for carbonic anhydrase (CA) cytochemically using the method of D.A. Riley, S. Ellis, and J. Bain (Neuroscience 13: 189, 1984). CA-positive cells comprised 11.1 +/- 0.7% of mucosal epithelial cells. Microplicated (MP) cells comprised 47.2 +/- 1.8% of CA-positive cells and displayed at least two distinct staining patterns: the first was characterized by reaction product that filled the luminal one-third, including the terminal web and microplicae. These cells possessed extensive microplicae, a morphological feature of ongoing H+ secretion. The second was characterized by reaction product distributed throughout cells, excluding the terminal web and microplicae, with greatest intensity in the luminal one-third below the terminal web. These cells possessed flattened microplicae, a morphological feature of diminished H+ secretion. Microvillated (MV) cells comprised 6.0 +/- 1.0% of CA-reactive cells. The basal layer was occupied by 46.8 +/- 1.7% of CA-positive cells, which were termed subluminal (SL) cells. SL cells were mitochondrial rich and did not contact the lumen. Extracellular CA staining was common between the lateral margins of contiguous mitochondrial-rich or non-mitochondrial-rich cells.

Animals↗
PubMed1991

Carbonic anhydrase and proton secretion in turtle bladder mitochondrial-rich cells.

Bladders from actively feeding turtles were processed for carbonic anhydrase (CA) cytochemically. CA-positive cells were identified as microplicated (MP) cells, microvillated (MV) cells, and subluminal (SL) cells. After acute enhancement of H+ secretion with 5% CO2, MP cells displayed extensive microplicae and a reduced density of apical subplasmalemmal vesicles, and they were CA reactive throughout a large part of the cytoplasm including the microplicae. After acute inhibition of H+ secretion with a pH 4.5 mucosal bath, CA staining was excluded from the microplicae and apical subplasmalemmal region of most MP cells, whereas microplicae varied from extensive to reduced, and subapical vesicle density remained elevated. MV cells were characterized by basolateral staining with sparing of the MV and apical subplasmalemmal region in all settings except 1) after 5% CO2 and 2) when MV cells were found in areas in which MP cells were stained to the lumen. These results indicate that CA is active at the site of H+ secretion in MP cells and is correlated with the acute acid-base status of the bladder.

Alkalies↗
PubMed1991

Effects of axotomy on the cholinesterase and carbonic anhydrase activities of axons in the proximal and distal stumps of rabbit sciatic nerves: a temporal study.

The temporal changes in transected sciatic nerves of rabbits were studied using recently developed histochemical techniques for discriminating between sensory and motor axons. A segment of the nerve was removed to inhibit spontaneous regeneration across the gap. Staining characteristics of the proximal and distal nerve stumps were studied at 1, 2, 3, 4, 9, and 35 days following axotomy and compared with control sciatic nerves. In the control and test nerves, subpopulations of myelinated sensory axons were identified histochemically by carbonic anhydrase (CA) staining, and a subset of alpha motor axons were visualized by cholinesterase (CE) staining. Axon staining patterns were reciprocal; i.e., sensory axons were CA-positive and CE-negative, whereas motor axons were CE-positive and CA-negative. Histochemical activities persisted at day 35 after axotomy in the proximal stump and until day 9 after axotomy in the distal stump. This implies that these techniques may aid in both immediate and delayed primary nerve repair. With time, there is buildup of scar tissue adding to the proximal and distal stumps. Therefore, sections for demonstrating sensory and motor axons must be taken progressively further back from the nerve stump ends. Histochemical axon typing indicated that sensory axons regenerated earlier and to a greater degree than motor axons in the developing neuroma. Use of both the carbonic anhydrase and cholinesterase staining methods is more accurate than either technique alone as an adjunct for examining normal and injured peripheral nerves.

Animals↗
PubMed1990

Skeletal muscle fiber, nerve, and blood vessel breakdown in space-flown rats.

Histochemical and ultrastructural analyses were performed postflight on hind limb skeletal muscles of rats orbited for 12.5 days aboard the unmanned Cosmos 1887 biosatellite and returned to Earth 2 days before sacrifice. The antigravity adductor longus (AL), soleus, and plantaris muscles atrophied more than the non-weight-bearing extensor digitorum longus, and slow muscle fibers were more atrophic than fast fibers. Muscle fiber segmental necrosis occurred selectively in the AL and soleus muscles; primarily, macrophages and neutrophils infiltrated and phagocytosed cellular debris. Granule-rich mast cells were diminished in flight AL muscles compared with controls, indicating the mast cell secretion contributed to interstitial tissue edema. Increased ubiquitination of disrupted myofibrils implicated ubiquitin in myofilament degradation. Mitochondrial content and succinic dehydrogenase activity were normal, except for subsarcolemmal decreases. Myofibrillar ATPase activity of flight AL muscle fibers shifted toward the fast type. Absence of capillaries and extravasation of red blood cells indicated failed microcirculation. Muscle fiber regeneration from activated satellite cells was detected. About 17% of the flight AL end plates exhibited total or partial denervation. Thus, skeletal muscle weakness associated with spaceflight can result from muscle fiber atrophy and segmental necrosis, partial motor denervation, and disruption of the microcirculation.

Animals↗
PubMed1990

Rat hindlimb unloading: soleus histochemistry, ultrastructure, and electromyography.

Soleus muscle atrophy was induced by hindlimb unloading of male Sprague-Dawley rats (305 +/- 15 g) for 4, 7, and 10-14 days. Controls (291 +/- 14 g) were housed in vivarium cages. Soleus electromyogram (EMG) activity was recorded before and during tail suspension. Unloading caused progressive reduction in the muscle-to-body weight ratio. After 14 days, type I and IIa fibers decreased in area 63 and 47%, respectively. Subsarcolemmal mitochondria and myofibrils were degraded more rapidly than intermyofibrillar mitochondria and the cell membrane. After 10 days, 3% of the fibers exhibited segmental necrosis; affected fibers were all high-oxidative type IIa fibers. This suggested ischemic injury. By 13 days, 30% of the fibers possessed central corelike lesions involving primarily type I fibers. Video monitoring revealed abnormal plantar flexion of the hindfeet by 4 days; this posture shortened the soleus working range. Corelike lesions indicated adaptation to the shortened length. No morphological signs of denervation were detected. EMG activity shifted from tonic to phasic, and aggregate activity was 13% of normal after 7 days. These findings indicate that the atrophy and pathological changes result from unloaded contractions, reduced use, compromised blood flow, and shortened working length.

Adenosine Triphosphatases↗
PubMed1989

Morphological study of the innervation pattern of the rabbit sinoatrial node.

The pattern of nerves, ganglia, and fine nerve processes in the adult rabbit sinoatrial node, identified by microelectrode recording, was defined by staining histochemically for cholinesterase followed by silver impregnation. A generalized repeatable pattern of innervation was recognized, including 1) a large ganglionic complex inferior to the sinoatrial node; 2) two or three moderately large nerves traversing the sinoatrial node parallel to the crista terminalis; 3) nerves entering the region from the atrial septum, the superior vena cava, and the inferior vena cava; and 4) a fine network of nerve processes, particularly extensive in the morphologically dense small-cell part of the sinoatrial node. When the site of initial depolarization in the node was located and marked by a broken-off electrode tip, it was found, after cholinesterase staining, to be characterized by a cluster of cells enclosed in a nest or basket of fine nerves. Similar nested cell clusters were observed elsewhere in the sinoatrial node in this same preparation and in other hearts. A complex interweaving of atrial muscle fibers was observed medial and inferomedial to the sinoatrial node, which may form the anatomical basis for the lack of conduction through this region. The morphological pattern of nerves, ganglia, and myocardial cells described in this study emphasizes the complexity of innervation of the sinoatrial node, including its intrinsic neural elements. Cholinesterase/silver staining can be useful in the definition and comparison of electrophysiologically identified sites within the sinoatrial node.

Animals↗
PubMed1988

Identifying motor and sensory myelinated axons in rabbit peripheral nerves by histochemical staining for carbonic anhydrase and cholinesterase activities.

Carbonic anhydrase (CA) and cholinesterase (CE) histochemical staining of rabbit spinal nerve roots and dorsal root ganglia demonstrated that among the reactive myelinated axons, with minor exceptions, sensory axons were CA positive and CE negative whereas motor axons were CA negative and CE positive. The high specificity was achieved by adjusting reaction conditions to stain subpopulations of myelinated axons selectively while leaving 50% or so unstained. Fixation with glutaraldehyde appeared necessary for achieving selectivity. Following sciatic nerve transection, the reciprocal staining pattern persisted in damaged axons and their regenerating processes which formed neuromas within the proximal nerve stump. Within the neuromas, CA-stained sensory processes were elaborated earlier and in greater numbers than CE-stained regenerating motor processes. The present results indicate that histochemical axon typing can be exploited to reveal heterogeneous responses of motor and sensory axons to injury.

Animals↗
PubMed1988

In vitro differentiation of quail neural crest cells into sensory-like neuroblasts.

This study shows that quail neural crest cells can differentiate in vitro into sensory-like neuroblasts. The putative sensory neuroblasts were large and spherical, possessing large diameter, bipolar or pseudo-unipolar, long processes that lacked multiple varicosities characteristic of autonomic neurons. They bound HNK-1, a monoclonal antibody against a cell surface epitope expressed by early neural crest cells but not by young neural tube-derived cells. Many of the sensory-like neuroblasts had substance P (SP)-like immunoreactivity. Some exhibited histochemical carbonic anhydrase activity; carbonic anhydrase is shown in this study to stain a subpopulation of spinal sensory neurons in adult quail and embryos 9 days and older, whereas ventral root axons and neurons in sympathetic ganglia are non-reactive at all ages. Double staining indicated that unlike the multipolar neuroblasts developing in the same cultures, SP-like immunoreactive neuroblasts do not contain detectable levels of tyrosine hydroxylase or dopamine-beta-hydroxylase. Finally, the neuronal nature of the cultured sensory-like neuroblasts was further documented by double labeling for antibodies against the 68 kDa neurofilament polypeptide and substance P.

Animals↗
PubMed1988

Quantitation and immunocytochemical localization of ubiquitin conjugates within rat red and white skeletal muscles.

We employed solid-phase immunochemical methods to probe the dynamics of ubiquitin pools within selected rat skeletal muscles. The total ubiquitin content of red muscles was greater than that of white muscles, even though the fractional conjugation was similar for both types of muscle. The specificity for conjugated ubiquitin in solid-phase applications, previously demonstrated for an affinity-purified antibody against SDS-denatured ubiquitin, was retained when used as a probe for ubiquitin-protein adducts in tissue sections. Immunohistochemical localization revealed that differences in ubiquitin pools derived from the relative content of red (oxidative) vs white (glycolytic) fibers, with the former exhibiting a higher content of ubiquitin conjugates. Subsequent immunogold labeling demonstrated statistically significant enhanced localization of ubiquitin conjugates to the Z-lines in both red and white muscle fiber types.

Animals↗
PubMed1988

Catalase-positive microperoxisomes in rat soleus and extensor digitorum longus muscle fiber types.

The size, distribution, and content of catalase-reactive microperoxisomes were studied cytochemically in slow-twitch oxidative (SO), fast-twitch oxidative glycolytic (FOG), and fast-twitch glycolytic (FG) fibers of soleus and extensor digitorum longus (EDL) rat muscles. Fiber types were classified on the basis of mitochondrial content and distribution, Z-band widths, and myofibril size and shape. Microperoxisomes were generally located between myofibrils at the I-bands. The absence of crystalloid inclusions prevented positive identification of microperoxisomes in nonreacted and aminotriazole-inhibited muscles. EDL and soleus SO fibers possessed the largest microperoxisomes, whereas FOG and FG fibers of the EDL contained small- to medium-sized microperoxisomes. Comparing either microperoxisome number per muscle fiber area or microperoxisome area per fiber area revealed significant differences between fiber types with this ranking: soleus SO greater than EDL SO greater than EDL FOG greater than EDL FG. The present observations demonstrate that the content of catalase-positive microperoxisomes is greatest in the oxidative muscle fiber types. These cytochemical findings account for the higher catalase activity in homogenates of soleus muscles as compared to that of EDL muscles, because the soleus contains more oxidative fibers than EDL.

Animals↗
PubMed1988

Contraction-free, fume-fixed longitudinal sections of fresh frozen muscle.

Contraction damage occurring when longitudinal frozen sections of fresh unfixed muscles are thawed on microscope slides has limited histological examination of this tissue mainly to cross sections. Longitudinally oriented sections are advantageous for investigating properties that vary along the length of the muscle fibers. A fume fixation technique has been developed for preventing contraction of thick longitudinal frozen sections. The technique is compatible with histochemical staining of enzymes.

Animals↗
PubMed1987

Peripheral nerve carbonic anhydrase activity and chronic acetazolamide treatment of rats.

Examination of cranial nerves shows that the sensory infraorbital branch of the trigeminal nerve contains many carbonic anhydrase-reactive axons whereas axons of the motor facial nerve are non-reactive. This motor/sensory axon staining difference holds for both cranial and spinal nerves. Chronic treatment with acetazolamide produced no apparent changes in carbonic anhydrase histochemical activity or the structure of peripheral nerve fibers.

Acetazolamide↗
PubMed1987

Effects of methylmercury on the motor and sensory innervation of the rat extensor digitorum longus muscle.

This histochemical study examined the effects of chronic methylmercury (MeHg) intoxication on the motor and sensory innervation of extensor digitorum longus muscles. Light microscopic examination of silver-stained axons in the intramuscular nerve bundles of MeHg-treated rats showed Wallerian-like degeneration and a reduction in the number of nerve fibers. Disrupted axons were predominantly sensory because 22.2% of spindle afferents (Ia) and 90.0% of Golgi tendon organ (Ib) sensory fibers were completely degenerated whereas less than 1% of motor endings were totally destroyed. Partial disruption occurred in the cholinesterase and motor terminals of 13.7% of endplates. Our results demonstrated greater vulnerability of sensory nerves than of motor nerves to MeHg-induced degeneration. Thus, the abnormal reflexes, ataxia, and muscle weakness following MeHg poisoning appear related to reduction of proprioceptive feedback from muscles and tendons in addition to the documented lesions in the central nervous system.

Animals↗
PubMed1986

Colchicine-induced sprouting of the neuromuscular junction in the pigeon extensor digitorum longus muscle.

Colchicine-induced motor endplate sprouting in the extensor digitorum longus muscle of the pigeon was examined. Ten days after the drug application sprouting from the endplate arborizations and nodes of Ranvier were observed. No concomitant changes in endplate surface area or in the degree of terminal branching could be demonstrated. Similarities between the sprouting patterns of the pigeon endplate and the mammalian endplate are discussed.

Animals↗
PubMed1986

Models of disuse: a comparison of hindlimb suspension and immobilization.

The effects of 1 and 2 wk of hindlimb suspension (HS) on rat skeletal muscle function were determined and the results compared with those obtained previously with hindlimb immobilization (HI). Both models of disuse (HS and HI) primarily affected slow-twitch muscle. Each decreased the isometric twitch duration in the slow-twitch soleus; however, the HS-mediated effect was entirely a result of a shortened contraction time (CT), whereas HI reduced one-half relaxation time (1/2 RT) as well as CT. Soleus muscle mass and peak tetanic tension (Po) declined with disuse. The HS effect on muscle mass and Po was variable, however, for all experiments HS produced atrophy equal to or greater than HI. A major difference existed in the effects of HS and HI on the maximal speed of soleus muscle shortening (Vmax). One and 2 wk of HS produced increases in Vmax to 4.45 +/- 0.34 and 6.83 +/- 0.74 fiber lengths/s, respectively, compared with control velocities of 3.05 +/- 0.08. By contrast over a similar time period, HI had no significant effect on soleus Vmax. The increase in Vmax at 14 days of HS was associated with, and perhaps caused by, the increased expression of a second faster migrating isozyme of myosin. The new native isozyme comigrated with fast myosin, but its light chain subunits contained only LC1s and LC2s. The mechanism responsible for the increase is unknown. One plausible explanation is that the apparent HS-mediated modification in muscle fiber type is dependent on the elimination of loadbearing or isometric contractions, a condition that does not exist during HI.

Animals↗
PubMed1985

Colchicine-induced differential sprouting of the endplates on fast and slow muscle fibers in rat extensor digitorum longus, soleus and tibialis anterior muscles.

The patterns of sprouting of motor endplates were examined in fast extensor digitorum longus and slow soleus muscles and in tibialis anterior muscles containing fast and slow muscle fiber types. A histochemical technique combining nerve silver impregnation and endplate cholinesterase staining was developed for this task. Temporal examination of the innervation was conducted 3, 7 and 10 days after either a 45 or 90 min application of the ipsilateral sciatic nerve with 5 mM colchicine. This dosage of drug did not cause detectable axon or muscle fiber degeneration, unlike 60 mM which was highly neurotoxic. At 3 days following treatment with the lower concentration, there were no significant differences in the percentages of intranodal, preterminal and ultraterminal sprouts between the normal (non-treated), sham-treated, contralateral systemic-control and drug-treated groups of muscles. By 7 and 10 days, the muscles on the drug-treated side exhibited significant increases in the 3 types of sprouts. Collateral sprouting was uncommon: most outgrowths remained on the muscle fibers innervated by the parent axons. Endplates in the tibialis anterior muscles of the control and drug-treated groups were classified Complex, Intermediate or Simple according to the relative degrees of branching of the terminal arbors. The occurrence of endplate classes and muscle fiber types was correlated in the superficial and deep regions of this muscle. Complex endplates innervated fast glycolytic fibers, Intermediate endplates supplied fast oxidative glycolytic fibers, and Simple endplates served slow oxidative fibers. In response to colchicine, the endplates of the slow muscles sprouted more than those of fast muscles while the innervation of slow fiber types sprouted less than that of fast fiber types. Furthermore, intranodal sprouts were more prevalent in slow muscles and ultraterminal sprouts more numerous in fast muscles whereas intranodal sprouts predominated on fast fiber types and ultraterminal sprouts were characteristic of slow fiber types. These apparently contradictory results were reconciled when it was noted that soleus endplates were mostly Complex and Intermediate, and the extensor digitorum longus contained more Simple endplates. Thus, consistency of sprouting patterns among endplate types of the 3 muscles was recognized when the pre-existing branching patterns were considered. This indicated that the patterns of sprouting were determined by the motor neurons rather than the muscle fibers. The observed sprouting responses supported the hypothesis that colchicine treatment of motor axons caused muscle fibers to elaborate a diffusible sprout-inducing factor.

Aging↗