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Biomedical subjects

T Scott

Publications and source records attributed to T Scott.

At least 19 recordsLinked to original sources
PubMed1991

Neuronal inclusions of Parkinson's disease.

Two distinct neuronal inclusions occur in Parkinson's disease. The Lewy body is the diagnostic hallmark and is recognized by its eosinophilic body and unstained halo. It can be found in specific regions of the nervous system, where its frequency, size, shape, and structure differ. Large neurons of the dorsal vagal nucleus and sympathetic ganglia often contain particularly large quantities of Lewy-body-like matter. It consists of filament in the outer part and electron dense material in the core, the outer part staining with silver and with antibodies to neurofilament and tubulin. The pale body is restricted to the substantia nigra and locus ceruleus. It does not react with conventional stains, silver, or neurofilament antibodies, and has a homogeneous structure with a granular and vesicular surface texture. It contains sparse granular matter, vacuoles, and filaments, surrounded by melanin. The Lewy body and pale body may be juxtaposed or contiguous in some cells, but their distinct appearances and structures indicate that they are separate inclusions.

Antibodies, Monoclonal↗
PubMed1991

Transient erosion of the ulnar styloid process.

A patient with polyarthritis had radiographs of the wrists taken at presentation and again at 6 months. At presentation radiographs were normal, but repeat X-rays at 6 months showed complete erosion of both ulnar styloid processes. This did not correlate with the clinical picture of a mild synovitis. A third X-ray showed normal wrists, revealing the cause to be a positional artefact during the X-ray procedure. Clinicians should be aware of this 'catch'.

Arthritis↗
PubMed1989

Effect of age on adherence of Branhamella catarrhalis to buccal epithelial cells.

The role of adherence in the pathogenicity of Branhamella catarrhalis in lower respiratory tract infection in the elderly was investigated. Differential adherence of this organism to buccal epithelial cells of elderly inpatients, outpatients, and young controls was measured. The mean number of bacteria adherent per cell was 36.9 +/- 11.2, 40.2 +/- 6.1 and 16.5 +/- 12.8 for inpatient and outpatient elderly and young controls respectively (significantly different p less than 0.01, Student's t test). This significantly higher level of adherence in the elderly subjects suggests that increased adherence may contribute to the incidence of respiratory tract infection due to B. catarrhalis seen in this group.

Adult↗
PubMed1989

Abnormalities of the septum pellucidum in schizophrenia.

The authors present two cases of schizophrenia in young males who have malformations of the septum pellucidum, a thin sheet of cells and fibers located in the midline of the brain that separates the lateral ventricles. These cases are discussed in the context of newly proposed neurodevelopmental models of schizophrenia.

Adult↗
PubMed1988

Antagonists and agonists interactions with the muscarinic receptor of the rat large airways.

The muscarinic receptor in the rat large airway was characterized by radioligand binding experiments. Using I-quinuclidinyl (phenyl-4-[3H])benzilate ([3H]QNB) as the radioligand, the receptor appears to be homogenous. The receptor density was 23 fmol/mg of protein and the Kd value for [3H]QNB binding was 16 pM. Competition of the [3H]QNB binding for the receptor with selective antagonists and agonists was used to characterize the muscarinic receptor. The K0.5 values for the (M1)-selective antagonists pirenzepine and telenzepine were 210 and 20 nM, respectively. The M2a-selective antagonist AF-DX 116 and the M2b-selective antagonist hexahydrosila-difenidol had K0.5 values of 130 and 120 nM, respectively. By comparing the apparent affinities of these antagonists in the large airways to their affinities in rat heart, the large airway muscarinic receptor appears to be of the M2a type. Agonists competition curves of [3H]QNB binding to the receptor were shallow. The agonist curves were modeled to one- and two-site binding models. All agonists, including M1-selective agonists, gave preferred fits to two-site models. Guanine nucleotide in the assay caused right shifts of the competition curves and decreased the apparent proportion of the receptor population that was in the higher affinity state for the agonists. Thus, it is concluded that: 1) the rat large airway muscarinic receptor interacts with antagonists in a manner which support the hypothesis that the receptors are of the M2a subtype and 2) both the high and low agonist affinity states of the M2a receptor of the rat large airways are capable of interacting with M1 agonists.

Animals↗
PubMed1987

Mortality among Canadian military personnel exposed to low-dose radiation.

We carried out a cohort study of mortality among 954 Canadian military personnel exposed to low-dose ionizing radiation during nuclear reactor clean-up operations at Chalk River Nuclear Laboratories, Chalk River, Ont., and during observation of atomic test blasts in the United States and Australia in the 1950s. Two controls matched for age, service, rank and trade were selected for each exposed subject. Mortality among the exposed and control groups was ascertained by means of record linkage with the Canadian Mortality Data Base. Survival analysis with life-table techniques did not reveal any difference in overall mortality between the exposed and control groups. Analysis of cause-specific mortality showed similar mortality patterns in the two groups; there was no elevation in the exposed group in the frequency of death from leukemia or thyroid cancer, the causes of death most often associated with radiation exposure. Analysis of survival by recorded gamma radiation dose also did not show any effect of radiation dose on mortality. The findings are in agreement with the current scientific literature on the risk of death from exposure to low-dose radiation.

Canada↗
PubMed1987

Identification of a factor IX/IXa binding protein on the endothelial cell surface.

Endothelium provides a specific binding site for Factor IX/IXa which can propagate activation of coagulation by promoting Factor IXa-VIII-mediated activation of Factor X. In this report the endothelial cell Factor IX/IXa binding site has been identified and the coagulant function of the receptor blocked. Studies using [3H]Factor IX derivatized with the photoaffinity labeling agent N-succinimidyl-6-(4'-azido-2'-nitrophenylamino)hexanoate (SANPAH) and cultured bovine endothelial cells demonstrated cross-linking to a trypsin-sensitive cell surface protein of Mr approximately equal to 140,000. Immunoprecipitation of metabolically labeled endothelium with Factor IX derivatized with the cleavable cross-linking agent N-succinimidyl(4-azidophenyl)-1,3'-dithiopropionate and antibody to Factor IX demonstrated the endothelial cell origin of the Mr 140,000 cell surface protein. Blockade of the Factor IX/IXa binding protein by covalently linking SANPAH-5-dimethylaminonaphthalene-1-sulfonyl-Glu-Gly-Arg-Factor IXa or SANPAH-Factor IX prevented both specific Factor IXa binding and effective Factor IXa-VIII-mediated activation of Factor X on endothelium. Following extraction of endothelium with detergents, Factor IX/IXa binding activity was solubilized and could be assayed using a polyvinyl chloride plate binding assay. Western blots of cell extracts demonstrated binding of 125I-Factor IX at Mr approximately equal to 140,000 which was blocked by excess Factor IX, but not antisera to Factor VIII, von Willebrand factor, alpha 2-macroglobulin, or epidermal growth factor receptor. These data indicate that endothelium provides a distinct binding site for Factor IX/IXa consisting, at least in part, of a membrane protein which can modulate the coagulant activity of Factor IXa on the cell surface.

Animals↗
PubMed1987

The ultrastructure of the nervous tissue in a benign teratoma.

The ultrastructure of the nervous tissue in a benign ovarian teratoma is described. This tissue was organized into areas having both "meningeal" and "ependymal" surfaces, between which were found astrocytes, ependymal cells, neurones with synapses and microglia. These cells all had ultrastructural similarities to their normal counterparts in the nervous system. In addition, some signs of degenerative change--due possibly to the abnormal location of the nervous tissue--were observed. Oligodendrocytes and myelin were absent, possibly because of vascular insufficiency.

Adult↗
PubMed1987

Organ weights, T-cell proliferation, and graft vs host capabilities of hypothyroidic chickens.

Thiouracil-induced hypothyroidism reduced the thymus weights of young chickens. Thyroid weights were greater in thiouracil-fed (TF) chicks, and the circulating levels of triiodothyronine and thyroxine were lower. Thiouracil treatment resulted in higher relative adrenal weights and serum corticosterone concentrations. Absolute weights of adrenals were equivalent between control and TF groups. The TF chicks showed depressions of total white blood cell counts and numbers of lymphocytes. Monocyte and granulocyte numbers were unchanged from those of controls. Thiouracil treatment lowered the phytohemagglutinin M responsiveness of peripheral blood leukocytes (PBL). On the other hand, the PBL from TF chicks produced the higher graft vs host (GvH) response. Therefore, while the hypothyroidic state impaired cycling activity in T cells, this condition did not significantly influence a functional parameter of T cells, the GvH response.

Animals↗
PubMed1987

Internal pudendal pseudoaneurysm complicating an ischial pressure sore.

A 23-year-old paraplegic patient experienced two episodes of substantial hemorrhage from an ischial pressure sore. Computed tomography showed that the wound extended into the pelvis and retroperitoneum, and arteriography demonstrated a pseudoaneurysm of the internal pudendal artery. The artery was selectively embolized, permitting debridement and flap coverage uncomplicated by bleeding. Bleeding from a pelvic extension of a pressure sore can be a catastrophic combination of distorted anatomy and relatively inaccessible vessels. As in hemorrhagic complications of pelvic trauma, tumors, and radiation, arteriography and transcatheter embolization can localize and control the source of bleeding.

Adult↗
PubMed1987

Phonological similarity effects, memory span and developmental reading disorders: the nature of the relationship.

Eight-and 11-year-old poor readers of average and below average intelligence carried out a visually presented immediate memory task, recalling strings of similar- and dissimilar-sounding letters. Task difficulty was adjusted for each child by determining memory span for the dissimilar items prior to the memory task. All poor reader groups recalled significantly more dissimilar- than similar-sounding items, and the magnitude of these effects was comparable to those shown by their chronological and reading age controls. A close association was found between memory span and reading age, such that average intelligence poor readers had memory spans indistinguishable from those of their reading age controls. Furthermore, a highly significant correlation was found between memory span and reading age. However, it was concluded that this relationship could not be primarily due to a substantial immediate memory component in word recognition as the below average intelligence poor readers had poorer memory spans than the brighter poor readers, yet they had very similar reading ages. Additionally, a weaker association was found between memory span and non-word reading than between memory span and word reading. It was hypothesized that recognition difficulties may be the primary problem underlying both poor word recognition and immediate memory impairments in children with reading disorders.

Child↗
PubMed1978

An ultrastructure study of cerebellar lesions induced in mice by three inoculations of avirulent Semliki forest virus.

An ultrastructural study of cerebellar lesions involving axonal and myelin degeneration induced in adult Swiss A2G mice by 3 intraperitoneal inoculations of avirulent Semliki Forest virus is described. Cerebellar white matter samples examined by light and electron miscroscopy 21 days after the first virus infection revealed microcystic areas, degenerating axons, macrophages containing myelin debris as well as normal elements. By light microscopy foci of myelin loss were apparent. At 28 days groups of degenerating axons were apparent in the white matter. No virus was seen in any of the sections.

Animals↗