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Biomedical subjects

D Scott

Publications and source records attributed to D Scott.

At least 235 records · Page 13Linked to original sources
PubMed1993

Binding of hemin and congo red by oral hemolytic spirochetes.

Colony-forming units or cells in suspension of oral anaerobic spirochetes (Treponema denticola, Treponema vincentii and Treponema socranskii) bind hemin and Congo red. Hemin or Congo red binds to a hydrophobic polypeptide receptor that is located in the outer membrane of the bacterial cells and it has a relative molecular mass of 47 kDa. These oral spirochetes also lyse sheep erythrocytes to produce beta-hemolytic zones around colony-forming units. The oral spirochetes may acquire iron for growth when they lyse erythrocytes and bind heme from which they may sequester and transport iron into the cells.

Bacterial Outer Membrane Proteins↗
PubMed1993

Effects of acute acid loading on parathyroid hormone secretion and on urinary calcium and cAMP excretion in the growing lamb.

Growing lambs fed a diet containing NaHCO3 were made acidotic by intravenously infusing HCl at the rate of 1 mmol/min over a 4 h period. Acid infusion led to a fall in blood and urine pH and a prompt increase in urinary Ca excretion. This in turn led to a fall in plasma Ca concentration and a rise in parathyroid hormone (PTH) levels. Urinary cAMP excretion was unaffected by acid infusion. In separate experiments lambs made acidotic by feeding a diet containing NH4Cl were given infusions of PTH at the rate of 1 microgram/h. Infusion of the hormone was accompanied by a rise in plasma Ca and an increase rather than a decrease in urinary Ca excretion and no change in urinary cAMP excretion. These results point to the kidney as the primary site of response to acid loading in the lamb, a failure to reabsorb Ca in these conditions necessitating the release of PTH and an increase in bone resorption in order to maintain normal plasma Ca levels.

Acidosis↗
PubMed1993

Absence of an association between HLA-DRB1*04 and rheumatoid arthritis in newly diagnosed cases from the community.

OBJECTIVES: To determine HLA-DR4 and DR1 allele frequencies in a series of patients with newly diagnosed early inflammatory arthritis. METHODS: HLA-DR1 and DR4 frequencies were determined by oligonucleotide typing of 208 patients classified as having either rheumatoid arthritis (RA) or undifferentiated inflammatory polyarthritis. RESULTS: The frequency of occurrence of DR4 in these patients with RA did not differ significantly from that in controls in the United Kingdom (42 v 37%). HLA-DR1 was increased in the group with inflammatory polyarthritis (25 v 18%). CONCLUSIONS: The frequency of DR4 is not increased in newly diagnosed community based patients with RA. This supports the hypothesis that DR4 is less important as a marker for susceptibility to RA than it is for disease persistence or severity.

Arthritis, Rheumatoid↗
PubMed1993

Levitating lung lesions due to bronchiolitis obliterans organizing pneumonia.

A 68-year-old man developed symmetrical bibasal infiltrates. Transbronchial lung biopsy specimen demonstrated abnormalities consistent with bronchiolitis obliterans organizing pneumonia (BOOP). The infiltrates appeared to migrate cephalad over a period of months, gradually disappearing after reaching the pulmonary apices.

Aged↗
PubMed1993

Cytogenetic studies of workers exposed to styrene: a review.

In 17 of 50 cytogenetic studies (on chromosomal aberrations, micronucleus formation and sister chromatid exchange) in peripheral blood lymphocytes from a total of 667 workers in industries in which there is exposure to styrene, significant increases in the frequency of chromosomal damage have been reported when compared with unexposed controls. The positive or negative outcome of these studies is, however, unrelated to the extent of exposure to styrene. Furthermore, in the 17 investigations in which positive results were found, there is no convincing evidence of a positive dose-response relationship, in spite of the wide ranges of exposure and different methods of measurement. There are also serious discrepancies between findings on the chromosomal damaging effects of styrene in human lymphocytes in vitro and the types of damage reported in exposed workers. The findings are not consistent with the interpretation that styrene is responsible for the observed effects in workers. Several other chemicals identified in the environment of styrene workers have been reported to induce chromosomal damage in vitro and/or in vivo.

Chromosome Aberrations↗
PubMed1992

Spatial and temporal patterns of intracellular calcium in colonic smooth muscle.

Intracellular calcium [Ca2+]i measurements in cell suspension of gastrointestinal myocytes have suggested a single [Ca2+]i transient followed by a steady-state increase as the characteristic [Ca2+]i response of these cells. In the present study, we used digital video imaging techniques in freshly dispersed myocytes from the rabbit colon, to characterize the spatiotemporal pattern of the [Ca2+]i signal in single cells. The distribution of [Ca2+]i in resting and stimulated cells was nonhomogeneous, with gradients of high [Ca2+]i present in the subplasmalemmal space and in one cell pole. [Ca2+]i gradients within these regions were not constant but showed temporal changes in the form of [Ca2+]i oscillations and spatial changes in the form of [Ca2+]i waves. [Ca2+]i oscillations in unstimulated cells (n = 60) were independent of extracellular [Ca2+] and had a mean frequency of 12.6 +/- 1.1 oscillations per min. The baseline [Ca2+]i was 171 +/- 13 nM and the mean oscillation amplitude was 194 +/- 12 nM. Generation of [Ca2+]i waves was also independent of influx of extracellular Ca2+. [Ca2+]i waves originated in one cell pole and were visualized as propagation mostly along the subplasmalemmal space or occasionally throughout the cytoplasm. The mean velocity was 23 +/- 3 microns per sec (n = 6). Increases of [Ca2+]i induced by different agonists were encoded into changes of baseline [Ca2+]i and the amplitude of oscillations, but not into their frequency. The observed spatiotemporal pattern of [Ca2+]i regulation may be the underlying mechanism for slow wave generation and propagation in this tissue. These findings are consistent with a [Ca2+]i regulation whereby cell regulators modulate the spatiotemporal pattern of intracellularly generated [Ca2+]i oscillations.

Animals↗
PubMed1992

Local production of fibronectin by ectopic human retinal cells.

The distribution of fibronectin mRNA and fibronectin in adult human retina and epiretinal membranes was investigated by in situ hybridisation and immunohistochemical techniques. The cells in normal adult retina contained little or no fibronectin mRNA and the retina only showed fibronectin immunoreactivity in retinal vessels. The cells in detached neuroretina did not contain fibronectin message but the vitreoretinal interface of the detached retina exhibited variable fibronectin immunoreactivity. Retinal glia, retinal pigment epithelium and fibroblast-like cells in membranes at the vitreoretinal juncture (epiretinal membranes) showed variable labelling with the fibronectin mRNA probe and all the membranes immunostained for fibronectin. No difference could be detected between membrane cell types in the intensity of labelling with the mRNA probe or for fibronectin immunoreactivity. The results indicate that cells in situ in attached and detached adult human retina do not produce fibronectin. Although fibronectin at the vitreoretinal juncture in retinal detachment is probably partly derived from plasma fibronectin resulting from breakdown of the blood-retinal barrier, ectopic retinal cells produce fibronectin and contribute to the glycoprotein epiretinal membranes.

Adolescent↗
PubMed1992

Early identification of maternal depression as a strategy in the prevention of child abuse.

Maternal suicide and infanticide are merely the extreme tip of the iceberg of psychological and social morbidity associated with post-partum depression. Despite research indicating an association between maternal depression and disturbed parent-child interaction, maternal depression has been largely ignored in the literature on child maltreatment and in child protection practice. Practitioners should be alert to the potential risks to the child associated with maternal depression. In cases where child abuse has occurred, they should consider the possibility that the mother is depressed and that this needs to be treated as a problem in its own right. In terms of prevention of child maltreatment, early identification of maternal depression is an important strategy in which primary health workers have an important role. This study investigates the feasibility of broadening the traditional infant health focus of the role of the Australian Maternal and Child Health Nurse or Public Health Nurse to encompass maternal emotional and social well-being. Using quantitative and qualitative methods, the conditions under which mothers would find this acceptable, and the factors that facilitate or constrain such role redefinition are analyzed.

Adult↗
PubMed1992

Reaching vulnerable populations: a framework for primary service role expansion.

An ecological framework is presented for assessing the feasibility of expanding the roles of primary service providers. Role conflict, interprofessional tensions, role anomalies, training and supervision, practitioners' tacit knowledge, and service user acceptance are among the factors assessed. The use of this conceptual framework for reaching a broader client population is discussed, together with its implications for professional practice.

Community Mental Health Services↗
PubMed1992

A CD4-derived peptide carrier blocks acute HIV-1 infection in vitro and binds to gp120 in the presence of Walter-Reed stage 1-6 HIV+ sera.

A peptide containing amino acid residues 41-84 of the CD4 molecule was synthesized and coupled through a thioether bond to human serum albumin. This conjugate bound to gp120 with an affinity that was half that of CD4 and blocked the HIV infection in vitro with an efficacy tenfold lower than that of CD4. More importantly, the CD4 peptide-human serum albumin conjugate could bind to gp120 in the presence of HIV+ sera from 18 Walter Reed stage 1-6 patients.

Acquired Immunodeficiency Syndrome↗