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Biomedical subjects

W Robertson

Publications and source records attributed to W Robertson.

At least 37 records · Page 2Linked to original sources
PubMed1991

Mechanisms of hypophosphatemia in humans with heatstroke.

Hypophosphatemia is common in heatstroke, but little is known about its mechanism. We investigated 10 consecutive patients with heatstroke (mean age 58 +/- 2 yr) whose mean rectal temperature at admission was 42.3 +/- 0.2 degrees C. Eight patients presented with hypophosphatemia [0.48 +/- 0.08 mmol/l, normal range (NR) 0.8-1.4 mmol/l], associated with increased fractional excretion of phosphate (19.8 +/- 6.4%, NR 6-20%) relative to plasma phosphate levels and reduced renal threshold for phosphate (0.55 +/- 0.08 mmol/l glomerular filtrate, NR 0.8-1.4 mmol/l). Plasma parathyroid hormone (75.0 +/- 5 pmol/l) and calcium (2.24 +/- 0.02 mmol/l) levels and fractional excretion of calcium were normal (1.66 +/- 0.27%). There was no evidence of uricosuria or aminoaciduria, and only one patient had glucosuria. Arterial carbon dioxide was decreased in eight patients (28 +/- 1.1 Torr); however, none had elevated blood pH (7.35 +/- 0.02). The results suggest that heatstroke-related hypophosphatemia is associated with abnormal phosphaturia independent of the parathyroid hormone level, and there is no evidence of tubular dysfunction.

Aged↗
PubMed1988

Manic depressive psychosis: an alternative therapeutic model of nursing.

Traditionally, the approach to affective disorders has focused upon the biophysical aetiology of the disorder. Given that a significant proportion of the so called 'recovered' manic depressive population experience a relapse, the adequacy of traditional treatment methods is questionable. The nursing literature represents the view that manic depressive patients have little, if any, control over their condition and the nursing management, therefore, is predominantly custodial, supportive and directive in character. Recent research suggests that life events, in particular the patient's perception and interpretation of such events, are potentially significant in the development of manic depressive symptomatology. This paper reports some aspects of an on-going nursing research project which is evaluating the efficacy of a multi-model nursing management package. The therapeutic model of nursing under study is briefly discussed and results of locus of control measurements are presented, which compare a random sample of recovered manic depressive women with existing norms. A description is also given of an attribution schedule developed by the authors for the research project. This schedule attempts to specifically assess the patient's attitudes towards her control of her illness.

Attitude of Health Personnel↗
PubMed1987

Comparison of magnetic resonance imaging with somatosensory testing in MS suspects.

Two hundred patients suspected of having multiple sclerosis (MS), including 42 with progressive myelopathy and 11 with optic neuritis, were investigated with somatosensory evoked potentials (SEPs) and magnetic resonance imaging (MRI). Most had minimal neurological deficit, the mean Kurtzke scale being 2.65. There were 117 patients had two or more MRI lesions suggestive of MS, with a total of 527 lesions identified; 290 (55%) involved the somatosensory pathways, most commonly lying in the mid-periventricular region (thalamo-cortical radiations). There was good correlation between positive and negative MRIs and SEPs. The MRI was abnormal more frequently than the SEP, except in progressive myelopathy when both were abnormal with equal frequency. It is proposed that some cases of myelopathy in MS may be due to periventricular rather than spinal pathology. The morphology of the MRI lesion would favor conduction block not slowing of the SEP as being the prime abnormality. This appeared to be true of leg SEPs.

Adolescent↗
PubMed1987

Orbital lymphoproliferative and inflammatory lesions.

We reviewed the records and biopsy specimens of 38 patients with clinically similar orbital lymphoproliferative and low-grade inflammatory lesions referred to one ophthalmologist at the University of British Columbia between 1977 and 1984. Twenty-six patients had lymphoproliferative lesions, the main feature being a densely cellular population of small lymphocytes. This group was further divided into reactive lymphoid hyperplasia, malignant lymphoma, Hodgkin's disease and atypical lymphoid hyperplasia. Symptoms and signs were similar within the subgroups. The mean length of follow-up was 3.7 years. Of the 26 patients 14 had extraorbital lymphoproliferative disease, 9 had orbital recurrences and 2 died of widespread disease. Twelve patients had inflammatory lesions with distinctly different histologic features from those of the lymphoproliferative group. Symptoms and signs were similar to those in the latter group. The mean length of follow-up was 2.1 years. Four of the 12 had orbital recurrences; none had extraorbital disease or died of their disease. We feel that orbital lymphoproliferative lesions can easily be separated from clinically similar low-grade inflammatory lesions histologically and that they should be staged and followed like small lymphocytic lymphomas. Guidelines are given for handling these specimens in the laboratory.

Adult↗
PubMed1985

The effect of human bone matrix extracts on the biosynthesis of macromolecules by human mononuclear cells in culture.

In chronic rheumatoid arthritis, mononuclear cells (MC) accumulate in the subchondral bone and form a prominent part of both destructive lesions and repair reactions. A fraction from human bone matrix extracts (BME) stimulated glycosaminoglycan (gag) and glycoprotein synthesis by fibroblastic cells but its effects on MC metabolism had not been studied. A method was established for the study of incorporation of radioactive precursors into total protein, IgG and gag synthesized and secreted by peripheral blood MC cultured in microwells in the presence or absence of Concanavalin A (ConA). Relatively low concentrations of BME suppressed spontaneous synthesis of radioactive IgG (protein A bound) and TCA precipitable protein but had little effect on gag synthesis. In general, stimulation of the cultures with ConA overcame the inhibitory effects on protein synthesis by the BME. A large stimulation of gag synthesis induced by ConA was not affected by BME. The interactions between the BME and the stimulatory effect of ConA on DNA synthesis were studied in detail and were found to be complex, not immunologically specific and appeared to be due to binding of lectin by the carbohydrate moieties of the glycoproteins in the BME. On the basis of a model of the lectin-BME interaction, the hypothesis is postulated that the carbohydrate moieties of subchondral bone glycoproteins may have the capacity to act as a solid state "trap" for certain circulating antigens which may then also interact with surface glycoproteins of the MC accumulating in the subchondral bone. The physiological role of gag synthesis by MC is not known.

Arthritis, Rheumatoid↗
PubMed1984

The effect of solubilized bone matrix fractions from different mammalian species on glycosaminoglycan synthesis by cultured fibroblasts.

Human and bovine bone matrices were extracted with salt solutions of different composition and the extracts tested for stimulation of incorporation of radioactivity from [3H]glucosamine and [35S]SO4 into the hyaluronic acid and chondroitin sulfate of the cell pellet, the cell surface and the medium fractions of human synovial cells in culture. Stimulatory activity was extracted with a solution of 0.3 M EDTA in 2.5 M NaCl from bovine but not human bone. Subsequent extraction of the residues with 4 M guanidinium hydrochloride yielded activity from both matrices. A major stimulation of incorporation of radioactivity was observed in the cell surface fractions. Human synovial cells constitute a more sensitive assay system for the stimulatory activity than rabbit synovial cells.

Animals↗
PubMed1984

Modulation of mitogen-dependent lymphocyte stimulation by hyaluronic acid.

The stimulation of incorporation of [3H]-thymidine into mononuclear cells (MC) from human body by plant lectins was assessed in the presence of varying concentrations of hyaluronic acid (HA). The simultaneous addition of HA and phytohemagglutinin to MC cultures resulted in a decrease in the incorporation of radioactivity. The magnitude of the decrease was directly related to the concentration of HA added. Kinetic studies, however, indicated that the addition of HA after the initiation of DNA synthesis in the MC cultures also resulted in a decline of the rate of incorporation of radioactivity. The kinetic and analytical data suggest that DNA synthesis by MC in inflammatory arthropathies might be modulated by the HA rich microenvironment of the joint and that this modulation could also occur even if the MC were stimulated before they reached the joint tissues.

Arthritis, Rheumatoid↗
PubMed1983

Plasma concentrations of delta-9-tetrahydrocannabinol and impaired motor function.

Fifty-nine volunteer subjects were allowed to smoke marijuana cigarettes until a satisfactory level of 'high' was obtained. They then had blood samples taken 5, 30, 90 and 150 min following smoking after which they were tested with the roadside sobriety test. Attempts to correlate passing or failing on three coordination tests with plasma concentrations of delta-9-tetrahydrocannabinol (THC) showed that if concentrations measured at 5 min were ignored, failures were almost inevitably associated with plasma concentrations of THC above 25-30 ng/ml. Overall, 94% of subjects failed to pass the test 90 min after smoking and 60% after 150 min, despite the fact that by then plasma concentrations were rather low. It would seem that establishing a clear relation between THC plasma concentrations and clinical impairment will be much more difficult than it has been for alcohol.

Adult↗
PubMed1983

Control of glycosaminoglycan synthesis and connective tissue differentiation in culture by solubilized bone matrix fractions.

Implantation of decalcified bone matrix in rodents induces the formation of new cartilage and bone by responding cells. Extraction of the bone matrix with high ionic strength solutions, followed by solubilization of part of the extract in isotonic salt solution, yielded material which stimulated glycosaminoglycan (GAG) synthesis by monolayers of fibroblastic cells. Bone is greatly enriched in this stimulatory activity compared to other connective tissues. However, fibroblastic cells from different sources respond to the stimulatory effect of low concentrations of the solubilized material. Kinetic studies of the GAG synthesized and secreted by the cultured cells revealed that a major stimulation of GAG secretion occurred at the cell surface as an early event following stimulation with the bone matrix extract. GAG accumulation in the culture medium occurs at a greater rate in cultures that have been stimulated with the bone matrix extract than in controls.

Animals↗
PubMed1982

Primary orbital schwannomas.

Seven histologically proved cases of primary orbital schwannoma have been seen at the University of British Columbia Orbital Clinic between September 1976 and December 1980. We describe here their varied clinical presentations, preoperative investigations, operative findings, and appearances on light and electron microscopy. Although no single feature is pathognomonic, a multiplicity of clinical, radiographic, and surgical features point to this lesion. Of preoperative investigations the computed tomography scan was the most helpful, especially in localising the lesion. Of the 7, 4 were intraconal and 3 were extraconal. The surgical approach was dictated by tumour site and included anterior, lateral, and panoramic orbitotomies. At surgery the nerve of origin of 4 of the tumours was identified. All tumours were excised totally or subtotally. There has been no recurrence to date.

Adult↗
PubMed1981

Characterization of the effect of aphidicolin on adenovirus DNA replication: evidence in support of a protein primer model of initiation.

Adenovirus DNA replication is inhibited by aphidicolin but the inhibition clearly has different parameters than the inhibition of purified DNA polymerase alpha. In adenovirus infected Hela cells, 10 micrograms/ml of aphidicolin reduced viral DNA synthesis by 80%. Cellular DNA synthesis was inhibited by 97% at 0.1 microgram/ml. 10 micrograms/ml of drug had no effect on virus yield or late protein synthesis though higher concentrations of drug (50 micrograms/ml) caused an abrupt cessation of late protein synthesis and 100 micrograms/ml reduced virus yield by 3 logs. Concentrations of the drug from 0.5 microgram/ml to 10 micrograms/ml were found to dramatically slow the rate of DNA chain elongation in vitro but not stop it completely, so that over a long period of time net incorporation was reduced only slightly compared to the control. 50 micrograms/ml or 100 micrograms/ml of drug completely inhibited incorporation in vitro. Initiation of viral DNA replication - covalent attachment of dCMP to the preterminal protein - occurs in vitro. This reaction was found to be insensitive to inhibition by aphidicolin. We thus conclude that aphidicolin exerts its effect on adenovirus DNA chain elongation, but not on the primary initiation event of protein priming.

Aphidicolin↗
PubMed1979

The 'DNA-membrane complex' of Escherichia coli B/r. Its composition and properties and the fate of nascent and genome DNA during DNA synthesis.

The composition and properties of 'DNA-membrane complex' of Escherichia coli B/r have been investigated. The 'complexes' contain most of the DNA and membrane of the cells, and about 50% and 25% of the RNA and protein respectively. The properties of DNA synthesized by the 'complexes' are described and the process is concluded to be largely mediated through polymerase I. Nascent DNA synthesized by the 'DNA-membrane complexes' was of two main classes, one of molecular weight around 600,000--800,000 and the other of higher molecular weight. Polynucleotide ligase activity was not detectable. The onset of synthesis coincided with the dissociation of at least 70% of the genome DNA and all of the nascent DNA from the 'complexes' and was concomitant with the action of a nuclease on parental DNA. This nuclease activity was not ATP-dependent.

Adenosine Triphosphate↗