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J S Edwards

Publications and source records attributed to J S Edwards.

At least 55 records · Page 3Linked to original sources
PubMed1989

Central projections of a homoeotic regenerate, antennapedia, in a stick insect, Carausius morosus (Phasmida).

Homoeotic appendages provide a system for the analysis of neural path-finding in which the appendage is mismatched with its segmented ganglion. Central projections of sensory neurons from homoeotic antennapedia regenerates induced by antennal amputation in the stick insect, Carausius morosus, are described. The majority of afferent axons project to the olfactory lobe as in the normal antennal nerve, but they do not give rise to compact glomeruli. Nor does the form of the projection resemble that of leg sensory nerves in thoracic ganglia. The projection of antennapedia regenerate neurons in Carausius resembles the antennapedia mutant of Drosophila except that some primary afferents bypass the olfactory lobe and take several courses through the brain, sometimes reaching distant contralateral areas. It appears that these wandering fibers, having bypassed the olfactory lobe, tend to follow established tracts and to arborize or to deviate at circumscribed synaptic areas. The behavioral evidence for sensory input from antennapedia regenerates is equivocal.

Animals↗
PubMed1989

Immunocytochemical evidence for the presence of histamine and GABA in photoreceptors of the barnacle (Balanus nubilus).

Biochemical evidence indicates that GABA and histamine may both be synthesized by barnacle photoreceptors (Koike & Tsuda, 1980; Timpe & Stuart, 1984; Callaway & Stuart, 1989b). We used antisera against GABA- and histamine-protein conjugates to determine whether the photoreceptors contain either or both of these antigens. Both antisera labeled all of the photoreceptors in each of the three ocelli. Histamine-like immunoreactivity was found throughout each photoreceptor cell but was most intense at their presynaptic terminals. Histamine-like immunoreactivity was blocked by preincubation of the antibody either with histamine or with a histamine-protein conjugate. GABA-like immunoreactivity was found in all parts of the photoreceptors including the cell body, axon, rhabdomeric dendrites, and presynaptic terminals. GABA-protein conjugates blocked the GABA-like labeling of the photoreceptors, while protein conjugates with histamine, L-glutamate, L-glutamine, beta-alanine, and taurine did not. Histamine-like immunoreactivity in the supraesophageal ganglion was confined to the photoreceptor terminals and a second, loose plexus of endings in the main neuropil. GABA-like immunoreactivity, in contrast, was found in approximately twenty-five pairs of neurons of this ganglion. In the cirral nerves, which are expected to contain inhibitory motoneurons, unidentified axons also labeled with the GABA antiserum.

Animals↗
PubMed1989

Pharmacokinetics of nitrendipine in the elderly.

The acute and short-term pharmacokinetics of the calcium antagonist nitrendipine were investigated in 18 elderly subjects (9 healthy volunteers and 9 hypertensive patients). The subjects received nitrendipine 10 mg twice daily for 7 days and the pharmacokinetics profiles for days 1 and 7 were compared for evidence of drug accumulation. In the healthy volunteers, neither the area under the curve (AUC) nor Cmax were significantly affected by nitrendipine treatment, although T1/2 was significantly increased on day 7. In the hypertensive patients, AUC was higher on day 7 than day 1, although this was only marginally significant (p = 0.050); Cmax and T1/2 were unchanged. Nitrendipine significantly reduced both systolic and diastolic blood pressure in the hypertensive patients but had no effect on the blood pressure of the healthy normotensive volunteers. Nitrendipine does not appear to accumulate significantly when given twice daily to elderly volunteers and hypertensive patients.

Aged↗
PubMed1988

Developmental modulation of a glial cell-associated glycoprotein, 5B12, in an insect, Acheta domesticus.

The expression of an insect (Acheta domesticus) adult glial cell-specific antigen, 5B12 undergoes major changes during development. The 5B12 antigen is detected as early as 20-25% of embryonic development, when immunoreactivity is distributed throughout the periphery, present at the luminal surface of epithelial cells which compose developing limb buds, sensory appendages, and the body cavity. The antigen is also localized on the cell surface of neural elements within commissural tracts in the embryonic CNS. 5B12 is secreted extracellularly in the periphery, where it is associated with the embryonic basal lamina in developing cercal sensory appendages. Luminal surface expression is transient, and disappears by 95% of embryonic development. As development proceeds, 5B12 distribution becomes more restricted, so that in the adult the antigen is predominantly associated with specific glial elements within the nervous system where it occurs as a specialized component of the extracellular matrix. The 5B12 antigen is also associated with discrete central and peripheral fiber tracts. Antigen 5B12 is present in whole embryos and in the adult CNS as a Mr 185-kDa glycoprotein. Distinct carbohydrate moieties with chondroitin sulfate-like properties are situated on the 5B12 epitope. Thus the glia-associated 5B12 macromolecule has the characteristics of a small proteoglycan. Based upon features of its distribution, pattern of spatiotemporal expression, and biochemical properties, it is speculated that 5B12 participates in events related sequentially to the development and the function of the insect nervous system.

Age Factors↗
PubMed1987

Inhibition of exercise-induced asthma by nifedipine: a dose-response study.

1. The effect of three single doses of nifedipine on exercise-induced asthma has been examined in 11 asthmatic subjects. 2. On four separate days patients undertook 6 min of exercise on a treadmill 30 min after taking placebo or nifedipine 10, 20 or 30 mg administered double-blind and in random order. 3. Nifedipine had no significant effect on resting FEV1 measurements. 4. Nifedipine, in doses of 10, 20 and 30 mg, inhibited exercise induced bronchoconstriction, reducing the maximum fall in FEV1 from 30.8 +/- 3.5% after placebo to 21.9 +/- 3.4% (NS), 13 +/- 3.4% (P less than 0.01) and 15 +/- 3.9% (P less than 0.01) respectively. 5. This study has shown that the protective effect of nifedipine against exercise-induced asthma is dose related with the maximum inhibitory effect being observed with a single dose of 20 mg.

Adult↗
PubMed1987

Immunological probes reveal spatial and developmental diversity in insect neuroglia.

A set of monoclonal antibodies (MAbs) has been generated that recognizes distinct classes of neuroglia in the adult nervous system of the cricket Acheta domesticus corresponding to glial types distinguished by morphological criteria. These include antibodies that bind to the neuroglia of the ganglionic cortex, perineurium, neuropil, and glia associated with the glial lacunar system (interface) and fiber tracts. Another MAb specifically labels components of the neural lamella, a complex extracellular matrix secreted by underlying perineurial cells. Selected adult glial-specific MAbs recognize particular glial antigens expressed during embryonic development of Acheta. Immunohistochemical staining of frozen sections of late- (90-95%) and intermediate- (50-55%) stage whole embryos reveals that the spatial distribution, degree of tissue restriction, or level of expression of some glial determinants changes as development proceeds. Labeling of certain neuroblasts in the embryonic CNS at 50-55% development by an antibody (MAb 3G6) that binds to neuropil glia in the adult CNS implies that at least 1 class of insect glia may be generated by these cells.

Animals↗
PubMed1986

Mechanosensory appendages and giant interneurons in the firebrat (Thermobia domestica, Thysanura): a prototype system for terrestrial predator evasion.

Aspects of the structure and function of the abdominal cerci and caudal filament sensory systems, and associated giant interneurons of the thysanuran insect Thermobia domestica, the firebrat, extend comparative studies of a widespread predator evasion system. All elements of the cercal system, which is well known from diverse orthopteroid insects, are present in the primitively wingless thysanuran. In addition, a median terminal sensory appendage, the caudal filament, projects to the same general regions of the terminal ganglion but shows limited overlap of synaptic regions with cercal input. A segmental series of giant interneurons appears to be homologous with those of the orthopteroid insects. The cercal system, which may have evolved with the first terrestrial hexapods, reaches its zenith in the orthopteroid insects, but was replaced in holometabolan insects by visual startle mechanisms with descending giant interneurons.

Action Potentials↗
PubMed1986

Metabolic changes in deafferented central neurons of an insect, Acheta domesticus. II. Effects on cholinergic binding sites and acetylcholinesterase.

Following the finding that cercal deafferentation of developing giant interneurons in the terminal abdominal ganglion (TG) of the cricket Acheta domesticus reduces TG protein metabolism within target interneuron dendrites and somata (Meyer and Edwards, 1982), it is now shown that deafferentation alters the turnover of three macromolecules associated with cholinergic transmission in the cercal sensory-giant interneuron pathway. The labeled specific ligands 3H-quinuclidinyl benzilate and 125I-alpha-bungarotoxin were used to assay populations of putative TG muscarinic and nicotinic cholinergic receptors, respectively, in control and deafferented groups of ganglia. The AChE activity of TG was also determined by assay and histochemical methods. Long-term deafferentation sustained throughout postembryonic development markedly reduces the densities of both muscarinic and nicotinic binding sites in the TG; short-term deafferentation of adult TG also leads to characteristic alterations in the properties of all three cholinergic markers within several days. Rapid changes seen in adults thus correlate with ultrastructural data demonstrating loss of afferent terminals within hours of sensory appendage removal. We propose that peripheral innervation-dependent regulatory mechanisms operate in both the developing and adult insect nervous system. Such mechanisms may influence transsynaptically the synthesis and turnover of specific macromolecules, some of which may reside on the cell surface of insect central neurons that are part of the cercal sensory-giant interneuron system.

Acetylcholinesterase↗
PubMed1984

Central projections of first-order ocellar interneurons in two orthopteroid insects Acheta domesticus and Periplaneta americana. A comparative study.

The central projections of ocellar first-order interneurons in the cricket, Acheta domesticus, and the cockroach, Periplaneta americana, were examined in silver-intensified cobalt preparations. Ten morphologically different types of ocellar interneurons among a total of 44 are recognized in the cricket, and five different types among a total of 26 in the cockroach, indicating that these species have simpler ocellar systems than those described previously in locusts. Ocellar interneurons arborize in the following regions of neuropil in both the cricket and cockroach: the ocellar foci of the posterior protocerebrum, the posterior deutocerebrum, the protocerebral bridge, the ocellar synaptic plexus, ocellar nerves and tracts, and the lobula and medulla of the optic lobes. Ocellar first-order interneurons thus project predominantly to sites where they are likely to synapse with other ocellar and optic-lobe interneurons.

Animals↗
PubMed1983

A survey of manpower planning models and their application.

Since the late 1950s, much work has been done on developing models of manpower systems which may be used for the purposes of planning. Many organizations have made successful use of such models, but in spite of these successes, manpower planning models are only gradually coming into widespread use. The aim of this paper is to review the models which have been developed, concentrating on their assumptions and applications rather than on mathematical or statistical details. A common theme of successful applications is that good presentation of results and ease of use are more important to users than theoretical sophistication.

Forecasting↗
PubMed1982

Protein composition of the bovine mitochondrial ribosome.

The protein complement of the bovine mitochondrial ribosome has been analyzed by two-dimensional electrophoresis in polyacrylamide gels to determine the number and molecular weights of the ribosomal proteins. Salt-washed ribosomal subunits are found to contain a total of 85 ribosomal proteins, 84 of which are electrophoretically distinct between the two subunits. These proteins are also electrophoretically distinguished from those of cytoplasmic ribosomes. This large number of proteins does not appear to be due to contamination by cytoplasmic ribosomal proteins or by adherent nonribosomal proteins. The molecular weights of these proteins are considerably larger than those of Escherichia coli ribosomal proteins, and are similar to those of bovine cytoplasmic ribosomal proteins. The sum of the molecular weights of the 85 proteins agrees well with that predicted by physical chemical measurements of the total mass of protein in the two subunits. Bovine mitochondrial ribosomes thus contain about twice as much protein as RNA, a highly unusual composition in comparison to the other kinds of ribosomes which have been characterized to date. In addition, it appears that the ribosomal proteins themselves are less basic than the proteins of most other ribosomes.

Animals↗
PubMed1982

Metabolic changes in deafferented central neurons of an insect, Acheta domesticus. I. Effects upon amino acid uptake and incorporation.

Chronic cercal deafferentation of the terminal ganglion in developing crickets (Acheta domesticus), which is known to suppress normal development of giant interneuron dendritic arborizations is shown here to reduce [3H]leucine uptake and incorporation into ganglion proteins. Short term deafferentation of adult crickets, in contrast, does not depress amino acid uptake and incorporation significantly. Following unilateral long term deafferentation of the terminal ganglion, a comparison was made of the [3H]leucine incorporation into primary dendritic processes and somata of deafferented and normally innervated medial giant interneurons (MGIs) within the same ganglion by means of quantitative autoradiography. Grain densities within dendrites of deafferented MGIs were significantly lower than in paired control MGIs' grain densities within somata of deafferented MGIs also were reduced, although the effects of deafferentation were less pronounced in somata than in target dendrites. These results imply a specific influence of afferent innervation on protein metabolism during growth and development of target postsynaptic elements.

Afferent Pathways↗
PubMed1981

The structure of the cercal sensory system and ventral nerve cord of Grylloblatta. A comparative study.

The structure of cercal sensilla, the cercal nerve and the central projections of the cercal sensory nerve of a notopteran (Grylloblatta sp.) are described and compared with other orthopteroid insects in which the cercal sensory system and central connections are well known. The cercal sensilla are similar to those of gryllids and blattids, but the gross structure of the cerci and distribution of cercal sensilla more closely resemble those of the Thysanura. The elements of the cercal sensory nerves and the central nervous system are similar to those of other orthopteroid insects, but extracellular material is present in greater quantity, and more extensive glial bundling of axons occurs in both the cercal nerve and central connectives. Glial structure, extracellular material and large multicristate mitochondria may be adaptations to life near O degrees C. The form of central projections of the cercal nerve and the configuration of the largest abdominal interneurons are unlike those of gryllids and Dictyoptera; they are similar to those of Dermaptera.

Abdomen↗
PubMed1981

Cercal sensory development following laser microlesions of embryonic apical cells in Acheta domesticus.

The hypothesis that pioneer fibers, which develop relatively early in the differentiation of insect appendages, serve to organize the peripheral sensory nerves was tested by ablating apical regions of the cercal rudiments in embryos of Acheta domesticus. Multiple nerve bundles rather than the normal middorsal and midventral pair of nerves were formed within the cercus following ablation of the cercal tip before pioneer fiber differentiation, but the cercal nerve was normal when lesions were made after formation of the pioneer fiber tracts and associated glia. These results indicate a necessary morphogenetic role for the pioneer fibers.

Animals↗
PubMed1980

Muscarinic cholinergic binding sites in an orthopteran central nervous system.

Homogenates of cricket (Acheta domesticus) central nervous system (CNS) specifically bind to potent muscarinic ligand [3H]-QNB. Binding assay and pharmacologic data indicate that the cricket CNS contains a high density of muscarinic cholinergic binding sites. These sites appear to be a unique class of invertebrate cholinergic receptor with properties distinct from those of previously described nicotinic receptors.

Animals↗
PubMed1979

Ultrastructure of the corpus cardiacum and corpus allatum of the house cricket Acheta domesticus.

The ultrastructure of the corpus cardiacum (CC) and corpus allatum (CA) of the house cricket, Acheta domesticus, is described. Axon profiles within the CC contain neurosecretory granules 160-350 nm in diameter which are indistinguishable from those found in type I neurosecretory cells of the pars intercerebralis and in the nervus corporis cardiaci I. The CC itself contains two cell types: intrinsic neurosecretory cells and glial cells. Intrinsic NSC cytoplasm contains Golgi bodies and electron dense neurosecretory granules 160-350 nm in diameter. Synaptoid configurations with 20-50 nm diameter electron lucent vesicles were observed within axon profiles of the CC. The structure of the CA is relatively uniform with one cell type predominating. Typical CA cells possess large nucleoli, active Golgi complexes, numerous mitochondria, and occassional microtubules. Groups of dark staining cells scattered throughout the CA of some animals were interpreted as evidence of cellular death.

Animals↗
PubMed1978

Fine structure of degenerating abdominal motor neurons after eclosion in the sphingid moth, Manduca sexta.

Ultrastructural aspects of the natural degeneration of a group of six motor neurons in the fourth abdominal ganglion of Manduca sexta are described. These motor neurons innervate intersegmental muscles that degenerate and disappear immediately after adult eclosion. The first detectable changes in the cell bodies appear 12h after eclosion and include disruption of the endoplasmic reticulum and an increase in the size and number of lamellar bodies. At 32h the nuclear membranes rupture, and the membranous and granular cytoorganelles segregate in different parts of the cell. At that stage the surrounding glial cells participate in the digestion of material from the degenerating neurons. From 72h onward the remaining neuronal structures become disrupted, and are finally transformed into a single, large lamellar body (residual body) within the glial profile. The degeneration pattern differs significantly from that of embryonic vertebrate neurons.

Abdomen↗