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J Burns

Publications and source records attributed to J Burns.

At least 289 records · Page 16Linked to original sources
PubMed1993

A technique for the tensile testing of demineralised bone.

The purpose of this study was to devise a method for the tensile testing of the organic component of demineralised bone. It was hoped that the method could be applied to determine whether an observed reduction in the strength of bone in copper-deficient rats could be attributed to a reduction in the cross-linking of collagen. Tensile testing of a fully demineralised specimen proved impossible to perform because of the difficulty in gripping the material, which tended to slide out of its holding clamps. The technique devised involved the demineralisation of only the diaphysis of the bone, leaving the bone ends intact. This enabled the bone to be gripped firmly at both ends in an Instron tensile testing machine. Elongation under loading of the demineralised diaphysis was measured by the Instron and a video recording was made of the elongation of the central portion. The strain was found to be uniform. Tensile strength was found to correlate with copper levels in the liver (r = 0.54, p < 0.05), although no significant differences were found between the strength, the stiffness, or the strain to failure for bone from the copper-deficient animals and bone from the normal controls. The test method itself should be useful in other studies in which the tensile properties of the organic phase of bone need to be measured.

Animals↗
PubMed1993

The medicolegal significance of proteoglycans in the tunica media of the vertebral artery.

After an apparently minor blow to the neck, the vertebral artery may rupture, with a fatal outcome. It is medico-legally important to assess whether the structural state of the artery is normal and, if not, whether this abnormality contributed significantly to the individual's death. Histological confirmation of such cases is rare, as are studies of the morphology of this artery. We examined the accumulation of proteoglycans at various sites along this transitional artery in 18 subjects of different ages. There are marked age-related increases in accumulations associated with fragmentation of elastic tissue within the tunica media, with no favoured site for such changes, but with substantially fewer proteoglycans within the intracranial portion of the artery. Focal large accumulations are occasionally seen in isolated segments of arteries, with overall modest counts. We discuss implications of these findings and recommend that multiple sections of artery be examined in cases of vertebral artery rupture in order to avoid misrepresentative assessment of the structural state.

Adolescent↗
PubMed1993

Analytical electron microscopy of chlorhexidine-induced tooth stain in humans: direct evidence for metal-induced stain.

Using analytical electron microscopy, we directly tested the hypothesis that transition metals and sulfur are the cause of chlorhexidine-induced tooth stain. Plaque scraped from the teeth of water-treated individuals or chlorhexidine-treated "non-stainers" was non- or lightly-stained and contained low concentrations of sulfur and transition metals. Tooth scrapings from heavily-staining chlorhexidine-treated individuals consisted of distinct unstained and stained regions. The stained regions were organic but were in close proximity to mineralized areas. Enhanced levels of sulfur and transition metals, particularly iron, were found in stained regions, whereas unstained regions contained low sulfur and metal levels similar to the water-treated or non-staining individuals. Excluding decreased mineralization, the major elemental change in heavily-stained plaque was an increase in sulfur, and to a lesser extent, iron and other transition metals. Sulphur and iron levels were directly correlated. Following chlorhexidine treatment with iron supplementation, staining was enhanced, the Fe/S ratio increased, and sulfur and iron remained correlated. These data support the hypothesis that transition metals and sulfur are the cause of chlorhexidine-induced tooth stain. The data are consistent with chlorhexidine treatment altering the incorporation into plaque of a natural sulfur-containing organic component of saliva or bacteria. This natural component appears to readily interact with transition metals, particularly iron, producing stained material.

Chlorhexidine↗
PubMed1993

Use of histomorphometry in the assessment of fatal vertebral artery dissection.

AIM: To assess morphometrically the structural changes, which occur with ageing, along the length of the vertebral artery. METHODS: A series of 36 vessels were removed at necropsy from subjects aged between 9 months and 86 years. Image analysis was used to measure the medial width, the circumference, the intimal: medial area ratio and the adventitial: medial area ratio along each artery. The artery from a case of fatal vertebral artery dissection, which occurred after a game of cricket and then chiropractic neck manipulation, was also examined in the same manner. The proteoglycan accumulation in the media was quantified using an eyepiece graticule. RESULTS: The vertebral arteries were, on average, larger around the origin of the vessel from the subclavian artery, and the adventitia were relatively thicker at this point, and also after piercing the dura mater. The media were much thinner within the intracranial segment and pronounced intimal thickening occurred with increasing age. The dissected artery showed undoubtable pre-existent structural abnormalities, in the form of massive proteoglycan accumulation, which predisposes an artery to dissection. CONCLUSIONS: These data should help pathologists faced with the task of assessing the underlying structural integrity of the vessel wall in cases of vertebral artery injury.

Adolescent↗
PubMed1993

Impaired mechanical strength of bone in experimental copper deficiency.

Copper, through its role as cofactor for lysyl oxidase, is essential for intra- and inter-molecular cross-links in collagen. Copper deficiency, in man and in animals, is associated with bone fragility ascribed to defective cross-links. To assess bone strength in copper-deficient animals, we designed a sensitive torsion-testing apparatus according to biomechanical considerations. Femora from 7 copper-deficient rats and from their pair-fed controls were tested in torsional loading until fracture. Significant decreases in the maximal sustained torque (t = 2.93, p < 0.05), in the ultimate angular deformation (t = 2.52, p < 0.05) and in the toughness (t = 2.88, p < 0.05) were demonstrated. In a complementary study, it was shown that the ash weight and the calcium content of the femora from the copper-deficient animals did not differ from those of the controls. It was likely, therefore, that the impaired mechanical strength was related to defects in the collagen component of bone.

Animals↗
PubMed1993

Effect of iron-folate supplementation on serum copper concentration in late pregnancy.

The effect of iron-folate supplementation on maternal serum copper concentration in late pregnancy (33 to 35 weeks gestation) was examined. In the 30 women who had taken daily iron-folate supplements since the start of the second trimester (11 to 15 weeks gestation), the median serum copper concentration was lower than that in the 27 women who had taken no supplements (p < 0.005). However, in the supplemented women the median values for serum iron concentration and blood hemoglobin concentration were higher, and the median value for serum transferrin concentration was lower, than the corresponding median values in the unsupplemented women (p < 0.001, p < 0.02 and p < 0.001, respectively). Further work is needed to determine whether the difference between the median values for serum copper concentration is due to a reduction in values in the women who took iron-folate, perhaps as a result of an interaction between iron and copper, or is due to an increase in values in the unsupplemented women secondary to their apparently reduced iron status.

Adolescent↗
PubMed1993

Product specification: the fifth discipline of health care.

In any given year, less than 50 percent of the total eligible population takes advantage of illness benefits. This certainly raises the issue of undercare. By specifying the periodic examination schedule for screening and preventive care, the product specification approach to quality medicine can preclude underservice of the beneficiaries. In addition, protocols and practice guidelines for care should lead to increased quality of care and better treatment outcomes. Elimination of the need for inspection will have a significant effect on the excessive administrative costs in the system, and the electronic medical record will eliminate duplication, provide for electronic fund transfer, and minimize administrative costs. Improved quality and lower costs will probably result from integrating the fifth discipline of product specification into health management.

Delivery of Health Care↗
PubMed1993

Placental and decidual histology in spontaneous abortion: detailed description and correlations with chromosome number.

OBJECTIVES: To determine the histopathology of failed pregnancy in clinically symptomatic women with no more than one prior pregnancy loss in order to provide baseline data, and to determine whether the histology of the conceptus in spontaneous abortions could predict a normal or abnormal chromosome number. METHODS: A review of all spontaneous abortions from which karyotypes were obtained between 1984-1991 yielded 224 cases in which maternal history indicated no more than one prior spontaneous abortion, a reliable date of last menstrual period (LMP), and available villous (221) and/or decidual/implantation site (175) pathology. Molar pregnancies were excluded. RESULTS: Multivariate logistic regression analysis showed a significant relationship between chromosome number and gestational age at loss as calculated from the LMP. Considering this confounder, a villous circulation indicating fetal life to 11 or more weeks, chronic intervillositis and villous infarcts (each P < .01), and decidual vasculitis (P < .05) were more frequent in chromosomally normal conceptions. Substituting possible variables into the logistic regression equation yielded predictions ranging from 88% likelihood of chromosomal abnormality to 97% likelihood of normal chromosome number. CONCLUSIONS: Histology can assist in assessing whether a spontaneous abortion is chromosomally normal or abnormal. There are many pathologic findings seen in spontaneous abortions regardless of karyotype; however, certain findings are more common in chromosomally normal abortions. These data provide a baseline for study of the histopathology of habitual abortion.

Abortion, Spontaneous↗
PubMed1993

In vitro transformation of epithelial cells by ras oncogenes.

Genes of the ras family of dominant transforming genes are frequently activated by specific point mutations in common human epithelial malignancies and also in many experimental tumour models. Testing of the hypothesis that ras activation is a critical event in tumorigenesis involves reconstruction of genetic events in vitro using appropriate epithelial models. This article reviews experimental transformation of human and rodent epithelial cells by ras oncogenes in vitro, alone and in combination with cooperating oncogenic events.

Animals↗
PubMed1993

A busy urban geriatric day hospital: analysis of one year's activity.

Lightburn Geriatric Day Hospital is a 30-place unit sited adjacent to Geriatric Assessment and Rehabilitation wards and three miles from the local district general hospital in east Glasgow. The service serves an urban population of 25,000 persons aged 65 or more. During 1991 a data capture form was used to prospectively record Day Hospital referral patterns and activity. There were 731 new patient referrals, accounting for a total of 5,780 patient attendances. Thirty-eight per cent of new patients attended without prior screening (unscreened General Practitioner (GP) referrals). Booked occupancy was 85.5%, actual occupancy 76%. The average period of attendance was three weeks (median number of attendances: 7) and 18% of attenders required in-patient care. Specific after-care arrangements were made for 85% of patients on discharge from day hospital. Low rates for re-attendance (within three months of day hospital discharge) and chronic attendance (more than three months) as well as favourable responses from surveys of both GPs and patients suggest effective use of the Day Hospital resource, but more direct measures of Day Hospital effectiveness are required.

Aged↗
PubMed1992

As reporters close in, execs learn to exhibit grace under pressure.

As healthcare continues at the forefront of the political agenda, hospital executives are finding both themselves and their institutions in the media's cross hairs. Yet not everyone feels comfortable talking to the press. Execs who feel unsettled in the glare of the media are gaining practical experience in media relations, crisis management and "damage control" strategies through various programs and seminars.

Communication↗
PubMed1992

Special units aim at dementia.

Nursing home providers, especially the large chains, are responding to calls for improved services for people with Alzheimer's disease and other dementia-related disorders by developing special-care units. While Alzheimer's programs have been in existence since the mid-1980s, the rising number of seniors who have the disease and their families' demands for quality long-term-care programs have resulted in rapid growth.

Aged↗
PubMed1992

1992 up & comers.

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Awards and Prizes↗