Search Results - (Author, Cooperation:J. P. Robinson)

2011-03-19

American Association for the Advancement of Science (AAAS)

0036-8075

1095-9203

Biology

Chemistry and Pharmacology

Computer Science

Medicine

Natural Sciences in General

Physics

2015-11-14

American Association for the Advancement of Science (AAAS)

0036-8075

1095-9203

Biology

Chemistry and Pharmacology

Computer Science

Medicine

Natural Sciences in General

Physics

Biomedical Research/*history ; Flow Cytometry/*history ; History, 20th Century ; History, 21st Century ; Single-Cell Analysis/*history

1471-4159

Blackwell Publishing Journal Backfiles 1879-2005

Medicine

Abstract: A pharmacological study was undertaken to determine whether the noradrenaline-stimulated breakdown of inositol phospholipids and the potentiation of isoprenaline-stimulated cyclic AMP by noradrenaline in rat cerebral cortex slices are mediated by the same α-receptor subtype. The rank order of potency of a range of α1 and α2 antagonists suggests that both responses may involve an α1 receptor, but there were several differences between the pharmacological profiles for the two systems. Although in both cases, all selective α1 antagonists were more potent than α2 antagonists, the rank orders and the absolute potencies differed for the two responses. The inhibition of the inositol phosphate response was characterised by a high α1/α2 antagonist ratio, and in most cases, Hill slopes of inhibition were consistent with the involvement of a single receptor site. Inhibition of the cyclic AMP response had a much lower α1/α2 antagonist ratio and generally exhibited Hill slopes less than one. Evidence has been provided suggesting that adenosine is involved in the potentiation of cyclic AMP and that other, as yet unidentified, factors may also be involved. Even in the absence of an adenosine component, the results presented support the suggestion that the potentiation due to noradrenaline is mediated by a receptor whose identity does not easily fit with the currently accepted classification of α adrenoceptors.

Electronic Resource

1471-4159

Blackwell Publishing Journal Backfiles 1879-2005

Medicine

Electronic Resource

1749-6632

Blackwell Publishing Journal Backfiles 1879-2005

Natural Sciences in General

Electronic Resource

0039-6338

Political Science

1432-0428

Diabetes mellitus ; diabetic neuropathies ; essential fatty acids ; axonal flow ; substance P ; nerve conduction ; myoinositol ; sorbitol ; streptozotocin ; rat

Springer Online Journal Archives 1860-2000

Medicine

Summary This study was designed to examine the effect of dietary supplementation with essential fatty acids (evening primrose oil — 5% weight:weight added to the diet) on acute neurophysiological and neurochemical defects in streptozotocin-diabetic rats. Diabetic rats, which were not given evening primrose oil, showed highly significant elevations of nerve sorbitol and fructose combined with a depletion of nerve myo-inositol. In those animals there was also a 40% reduction (p〈0.02) in the accumulation of axonally transported substance P-like immunoreactivity proximal to a 12 h sciatic nerve ligature together with reduced motor nerve conduction velocity (13% [p〈0.001] and 20% [p〈0.001] in two separate experiments). Treatment of other diabetic rats with evening primrose oil prevented completely the development of the motor nerve conduction velocity deficit without affecting sorbitol, fructose or myo-inositol levels or the deficit in axonal transport of substance P. In a second experiment, treatment of diabetic rats with evening primrose oil was associated with significant attenuation of the conduction velocity deficit, but not complete prevention.

Electronic Resource

1432-1106

Nucleus raphe magnus ; Spinal trigeminal nucleus ; Spinal cord ; Retrograde transport ; Fluorescent dyes

Springer Online Journal Archives 1860-2000

Medicine

Summary Retrograde transport of the fluorescent dyes Evans blue and 4,6-diamidino-2-phenyl indole (DAPI) has been used to study projections from the medullary raphe nuclei to the trigeminal nucleus caudalis and to the dorsolateral quadrant of the thoracolumbar cord in the rat. The majority of projecting neurones were found in n. raphe magnus (NRM) and its ventrolateral extensions over the pyramids and inferior olive. Double labelling experiments showed that 94% of raphe-trigeminal neurones sent a collateral branch to the nucleus in the contralateral brainstem. Similarly, 92% of raphetrigeminal neurones branched to supply the thoracolumbar cord. It is suggested that the widespread nature of the analgesia produced by electrical stimulation in NRM in conscious animals may be due to activation of a population of raphe neurones which inhibit the responses of neurones in the trigeminal nucleus and dorsal horn via an extensive system of collateral projections to these structures.

Electronic Resource

1432-072X

Methanobacterium formicicum ; Chemostat ; Growth parameters ; Hydrogenase ; Formate dehydrogenase

Springer Online Journal Archives 1860-2000

Biology

Abstract Growth of Methanobacterium formicicum strain MF was studied in pH-stat batch cultures and formatelimited chemostat cultures. The maxium rate of methanogenesis from formate occurred at pH 7.6 and 43°C and the maximum specific growth rate constant (μm) was 0.08 h-1. The K s and maximum growth yield (Y s max ) were 3.5 mM formate and 1.4 (g dry wt) mol01 formate respectively, and the maintenance coefficient (m) was calculated as 6.8 mmol formate (g dry wt)-1 h-1. The efficiency of electron transport phosphorylation during formate metabolism assuming Y ATP of 10.5 g mol-1 was about 20%. The specific activities of hydrogenase and formate dehydrogenase increased slightly with dilution rate.

Electronic Resource

1573-0727

Springer Online Journal Archives 1860-2000

Electrical Engineering, Measurement and Control Technology

Electronic Resource

1573-4919

Springer Online Journal Archives 1860-2000

Biology

Chemistry and Pharmacology

Medicine

Summary A discontinuous preparative polyacrylamide gel electrophoresis system has been developed and used to purify both the nicked and unnicked forms of tetanus toxin. The system was also used to prepare purified H and L chain peptides from the nicked toxin. The results show that the endogenous protease(s), which convert unnicked toxin to the nicked form, produce multiple species of nicked toxin, and heterogeneity in the H and L chains. The major amino termini of the toxins and their peptide components are: extract toxin, proline; filtrate toxin, proline, serine and asparagine; L chain, proline; and H chain, serine and asparagine. The L chain is located in the amino terminal position of the toxin molecule and the H chain the carboxy terminal end. A model is proposed to explain these results. Using the analytical ultracentrifuge, we have determined the molecular weights of extract and filtrate toxins to be 140 000 ± 5 000 and 128 000 ± 3 000, respectively. Using S DS-polyacrylamide gel electrophoresis we estimate the molecular weights of the H and L chains to be 87 000 and 48 000 daltons, respectively. Circular dichroic spectra of the toxins and their peptide components indicate that: the major tryptophanyl band in the toxin is contributed almost entirely by the H chain, the microenvironments of all the aromatics and disulfides in the two toxins appear to have small if any differences, the two toxins show little difference in their ordered secondary structure, and the two peptides when separated from one another still retain 80% of the helical structure that is present in the intact toxin but show a considerable loss of β-structure. The crystalline form of the nicked toxin has a hexagonal symmetry with two dimensional reciprocal lattice constants of 1/150 Å−1 and 1/150 Å−1. The crystals appear to belong to the two dimensional plane group P6 suggesting that each unit cell contains 6 or a multiple of 6 toxin molecules.

Electronic Resource

1573-4919

Springer Online Journal Archives 1860-2000

Biology

Chemistry and Pharmacology

Medicine

Summary Purified filtrate tetanus toxin was subjected to limited digestion with papain and the resulting fragments were separated by gel exclusion chromatography and characterized. One atoxic fragment was shown to react with antiserum against tetanus toxoid and was capable of inducing antibodies in rabbits that neutralized native tetanus toxin. The fragment had an estimated molecular weight of 56,000 by SDS polyacrylamide gel electrophoresis and 62,000 by sedimentation equilibrium. In the presence of a reducing agent, the fragment yielded two components with approximatec molecular weights of 23,000 and 32,000. Thus, it appears that the atoxic, immunogenic fragment is composed of two peptides joined by at least one disulfide bond. The fragment was examined by circular dichroism and data analysis indicated the presence of considerable β-structure, but little, if any, α-helicity. This is significantly different from the estimates for filtrate toxin, 29% α-helicity and 23% β-structure. Above 250 nm, the circular dichroic spectrum of the fragment was also distinct from that of intact toxin.

Electronic Resource

1573-4919

Springer Online Journal Archives 1860-2000

Biology

Chemistry and Pharmacology

Medicine

Summary Peripheral white blood cells have been shown to bind serum immunoglobins when prepared in low ionic strength sucrose solutions. The presence and distribution of Ig on neutrophils, monocytes and lymphocytes was described using an immunoferritin probe and the electron microscope. It appears that this approach reveals immunoglobulins associated with peripheral white blood cells that are not observed by the usual methods of examining these cell surfaces after preparation at physiological ionic strength.

Electronic Resource

1573-0603

Flow cytometry ; Muscle cell ; Porcine ; Transfection

Springer Online Journal Archives 1860-2000

Biology

Abstract A detailed methodology is described for fluorescence-activated cell sorting (FACS) of porcine muscle cells that have been transfected to express green fluorescent protein (GFP). Cells are liberated from porcine skeletal muscle and primary cultures are transfected with DNA encoding GFP. Primary cultures are subjected to immunocytochemistry using a primary muscle-specific monoclonal antibody followed by incubation with a phycoerythrin-conjugated second antibody. Transfected myoblasts aresorted from fibroblasts using forward angle light scatter and ninety degree light scatter, phycoerythrin fluorescence, and GFP fluorescence. These procedures allow for isolation of genetically-engineered porcine muscle cells more rapidly than traditional clonal selection procedures. Consequently, FACS provides porcine myoblast populations that retain the majority of their replicative capacity and are not contaminated with non-myogenic cells.

Electronic Resource

1432-0991

Springer Online Journal Archives 1860-2000

Biology

Medicine

Abstract A chemically defined medium (BGDM) has been developed specifically forBacteroides gingivalis. The medium contains 4 amino acids, 5 mineral salts, cysteine hydrochloride as a reducing agent, and the growth factors hemin and menadione. Eight strains ofB. gingivalis have been subcultured repeatedly in this medium with no apparent changes in colonial or cellular morphology. The metabolic end products of strains grown in this medium were reproducible and yielded patterns similar to those produced by cells cultured in complex media. The growth rates were about 50% slower than those of cells grown in a complex medium, and the growth rate constants ranged between 0.013 and 0.067 H−1. When the defined medium was supplemented with protein hydrolysates such as trypticase, proteose peptone, bactocasitone, or yeast extract, at concentrations up to 1.0%, growth increased. No such growth increase was observed in the medium supplemented with casamino acids. Thus a minimal medium can be formulated by adding one of the growth-enhancing protein hydrolysates to the defined medium at varying concentrations depending upon the growth yield required.

Electronic Resource