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Biomedical subjects

G L Scott

Publications and source records attributed to G L Scott.

At least 19 recordsLinked to original sources
PubMed2000

Identification of the secreted macromolecular immunogens of Staphylococcus aureus by analysis of serum.

The ability of sera to recognise secreted macromolecules of Staphylococcus aureus was examined by ELISA and Western immunoblotting. Individual secreted proteins were also studied using both human sera and sera from rabbits immunised with secreted macromolecules. Patients sera showed a wide range of IgG antibody titres to secreted macromolecules and whole bacteria. Controls showed a significantly lower IgG response. Western immunoblotting revealed that a significant number of secreted proteins were recognised by circulating IgG antibodies. Surprisingly, both the sera from controls and from patients recognised similar macromolecules including a number of potential virulence factors. The major difference was in the IgG binding to a 16-kDa component, which was recognised by the majority of the sera from infected individuals, but only by a small number of sera from healthy controls. The higher incidence of antibodies recognising the 16 kDa component may be related to our earlier finding that the major bone resorbing component of S. aureus is a heterodimeric protein containing a 16-kDa subunit, the activity of which could be blocked by sera.

Adult↗
PubMed1995

Acute promyelocytic leukaemia (M3): relapse with acute myeloblastic leukaemia (M2) and dic(5;17) (q11;p11).

Secondary leukaemia following treatment of M3 acute promyelocytic leukaemia (APL) is a rare event. We describe a patient in remission following chemotherapy for APL who relapsed with M2 acute non-lymphoblastic leukaemia (ANLL). The original t(15;17) (q22;q21) chromosome translocation was lost and replaced by a clone containing a dic(5;17) (q11;p11) abnormality. Southern genomic analysis demonstrated re-arrangements of the retinoic acid receptor varies; is directly proportional to (RAR varies; is directly proportional to) and PML genes in the APL blasts at presentation but not in the M2 ANLL marrow at relapse. The significance of unbalanced 5;17 translocations as markers for therapy-related secondary leukaemia is discussed.

Blotting, Southern↗
PubMed1993

Light scattering analysis of fibril growth from the amino-terminal fragment beta(1-28) of beta-amyloid peptide.

beta-Amyloid protein (beta-A/4) is the major protein component of Alzheimer disease-related senile plaques and has been postulated to be a significant contributing factor in the onset and/or progression of the disease. In the senile plaque, beta-A/4 appears as bundles of amyloid fibrils. The biological activity of beta-A/4 may be related to its state of aggregation. In this work, self-assembly, fibril formation, and interfibrillary aggregation of beta(1-28), a synthetic peptide homologous with the amino-terminal fragment of beta-A/4, were investigated. The predominant form of beta(1-28) detected by size-exclusion chromatography and polyacrylamide gel electrophoresis was apparently a tetramer which does not bind Congo red. Aggregates containing cross-beta sheet structures which bind Congo red and thioflavin T were observed at concentrations of approximately 0.3 mg/ml or greater. Concentrations of 0.5-1 mg/ml were necessary for aggregation into fibrils to be detectable by classical or quasielastic light scattering. Both fibril elongation and fibril-fibril aggregation occur over the time scale investigated. The kinetics of aggregation were much faster at physiological salt concentrations than at lower ionic strength. Ionic strength also appeared to influence the morphology of the fibril aggregates. The data indicate that sample preparation method and sample history influence fibril size and number density.

Amino Acid Sequence↗
PubMed1992

Treatment of haemophilic flexion deformities using the Flowtron intermittent compression system.

We have studied prospectively the use of the Flowtron intermittent compression system for the home treatment of fixed flexion deformities of elbows and knees, resulting from chronic haemophilic arthropathy. A total of 16 elbows (six unilateral and five bilateral), and 10 knees (six unilateral and two bilateral) in 11 patients were studied. Treatment caused a decrease in flexion contracture of the elbows from 41 +/- 3 degrees to 28 +/- 3 degrees (P < 0.001), an improvement of 32%. The knees showed a decrease in flexion contracture from 31 +/- 3 degrees to 20 +/- 2 degrees (P < 0.0001), an improvement of 35%. Prophylactic factor replacement was not used during the study and there were no bleeds attributable to the treatment. We conclude that the use of the Flowtron in home treatment of fixed flexion deformities in haemophiliac patients is safe, effective and cheap.

Chronic Disease↗
PubMed1992

Functional and morphological studies of mitochondria exposed to undecagold clusters: biologic surfaces labeling with gold clusters.

This study reports morphological and functional alterations observed in respiring isolated mitochondria when they are exposed to nonpenetrating, positive electrostatically charged synthetic undecagold clusters. Modification of the undecagold clusters positive charges change or prevent the functional effects and the binding to the outside surface of the mitochondria. The mitochondrial functional alterations are dependent on the oxidative phosphorylation capacity of the isolated organelles. The results of these experiments indicate that artificial undecagold may be useful to explore the molecular mechanisms of biological energy transducers which require electric charges separation, ionic fluxes, and electric surface properties.

Animals↗
PubMed1991

An algorithm for associating the features of two images.

In this paper we describe an algorithm that operates on the distances between features in the two related images and delivers a set of correspondences between them. The algorithm maximizes the inner product of two matrices, one of which is the desired 'pairing matrix' and the other a 'proximity matrix' with elements exp (-rij2/2 sigma 2), where rij is the distance between two features, one in each image, and sigma is an adjustable scale parameter. The output of the algorithm may be compared with the movements that people perceive when viewing two images in quick succession, and it is found that an increase in sigma affects the computed correspondences in much the same way as an increase in interstimulus interval alters the perceived displacements. Provided that sigma is not too small the algorithm will recover the feature mappings that result from image translation, expansion or shear deformation--transformations of common occurrence in image sequences--even when the displacements of individual features depart slightly from the general trend.

Algorithms↗
PubMed1990

Biochemical and morphological differentiation of acetylcholinesterase-positive efferent fibers in the mouse cochlea.

We have compared the biochemical expression of cholinergic enzymes with the morphological differentiation of efferent nerve fibers and endings in the cochlea of the postnatally developing mouse. Choline acetyltransferase (ChAT) and acetylcholinesterase (AChE) are present in the newborn cochlea at specific activities 63% and 25%, respectively, of their mature levels. The relative increases in ChAT, in AChE, and in its molecular forms over the newborn values start about day 4 and reach maturity by about day 10. The biochemical results correlate well with the massive presence of nerve fibers stained immunocytochemically for ChAT and AChE or enzymatically for AChE in the inner and outer hair cell regions. Ultrastructral studies, however, indicate the presence of only few vesiculated fibers and endings in the inner and outer hair cell regions. The appearance of large, cytologically mature endings occurs only toward the end of the third postnatal week. The discrepancy may be resolved in the electron microscopy using the enzymatic staining for AChE. Labeling is seen on many nonvesiculated fibers and endings in the hair cell regions, suggesting that the majority of the efferent fibers in the perinatal organ may be biochemically differentiated but morphologically immature. The results may imply that the efferents to inner and outer hair cells develop earlier than indicated by previous ultrastructral studies. Moreover, the pattern of development suggests that in the cochlea, as in other tissues, the biochemical differentiation of the efferent innervation may precede the morphological maturation.

Acetylcholinesterase↗
PubMed1990

Ultrastructure of the intercalated body, a novel organelle associated with fluid forming cells in the organ of Corti.

The intercalated body is a newly discovered organelle in the inner and outer spiral sulcus cells of the mouse organ of Corti. The organelle was found in the cochleas of 14-day and older intact mice and in organs in culture of corresponding ages. The organelle consists of a stack of interconnected cisternae of endoplasmic reticulum and of membrane bound rodlets that are intercalated between, and run parallel to, the cisternae. The cisternal membranes are predominantly smooth, but some may display ribosomes. Most rodlets are from 1 to 2 microns long, about 0.1 micron wide, and contain electron dense material. Mitochondria are commonly associated with or incorporated into the organelle. Some electron micrographs suggest that the rodlets may originate from modified mitochondria. It is our impression that the formation of the organelle begins with the apposition of cisternae and mitochondria. Cisternal-associated mitochondria appear to constrict, elongate, and lose their inner membranes. In both the intact animal and in culture, the cells of the inner and outer spiral sulci display microvilli, apical junctional complexes, lateral intercellular spaces containing interdigitating cell processes, and appear to be involved in fluid formation. Moreover, in culture, the cells of inner and outer spiral sulci as well as some cells proliferating in the outgrowth zone participate in fluid formation, producing large fluid pockets. All these cells commonly contain intercalated bodies. It is possible that in the intact animal, as in culture, intercalated bodies may play a role in fluid regulation in the immediate vicinity of the hair cells.

Animals↗
PubMed1986

Distribution of synaptic ribbons in the developing organ of Corti.

Studies of synaptogenesis in the developing organ of Corti in the intact mouse and in culture indicate that the inner and outer hair cells contain three populations of synaptic ribbons, i.e. ribbons adjacent to nerve fibres, free intracellular ribbons and misplaced ribbons apposed to non-neuronal elements. Ribbons adjacent to nerve fibres can be further classified into: ribbons synaptically engaged, ribbons participating in formation of presynaptic complexes only and ribbons that are not engaged to the hair cell membrane. In the developing innervated cultures the ribbon distributions are similar to those in the normal animal. Inner and outer hair cells differ in distribution of the ribbons. In the inner hair cells the ribbons adjacent to the nerve fibres are dominant (over 90%) and most of them (88%) are synaptically engaged. In the outer hair cells the presynaptic ribbons dominate the population (up to 60%) during the first postnatal week when the cells acquire afferent synaptic connections. This stage is followed by a marked reduction in the number of all ribbons. In the intact animal the rapid decrease results in a relative increase of misplaced and free ribbons. These changes are presumably due to the loss of some of the afferents. In the denervated hair cells the distribution of ribbons indicated the presence of conspicuous scatter. In the areas of incomplete denervation, however, the ribbons are apposed to the preserved fibres. Despite denervation, most of the ribbons develop the entire presynaptic complex in apposition to non-neuronal structures. The different populations of synaptic ribbons appear to reflect different stages in synapse formation. Possibly, the synaptic body originates in the interior of the hair cell and subsequently migrates to the cell membrane. In any case, a nerve fibre appears critical in influencing the location of the synaptic ribbon. At the apposition of the ribbon to the hair cell membrane, presynaptic densities are formed and the ribbon appears to become anchored. Typically, the nerve fibre membrane apposed to the presynaptic complex responds with the formation of postsynaptic densities.

Aging↗
PubMed1985

AIDS surveillance in haemophilia.

We suspected a patient attending our Haemophilia Centre had developed Acquired Immunodeficiency Syndrome (AIDS) and therefore immunological evaluation was performed on 43 patients with haemophilia and von Willebrand's disease attending the Centre. The index patient died of Pneumocytis carinii pneumonia. Thirty-one patients had either abnormal T cell subsets or helper/suppressor ratios. Thirty-two patients had hypergammaglobulinaemia. There was no direct correlation between these immunological abnormalities and the total amount or type of treatment received. T cell abnormalities were not confined to the 13 patients who had received the same batches of concentrate as the index case. The index case simultaneously contracted hepatitis B. He was the only patient to receive a large amount of the suspect batches of concentrate, not previously immune to hepatitis B.

Acquired Immunodeficiency Syndrome↗