PubMed Health⌕ Search

Biomedical subjects

H Robertson

Publications and source records attributed to H Robertson.

At least 37 records · Page 2Linked to original sources
PubMed1999

A simplified arteriovenous malformation model in sheep: feasibility study.

BACKGROUND AND PURPOSE: Recently, a swine model of a cerebral arteriovenous malformation (AVM) has been developed that closely resembles a human AVM of the brain. The creation of such a model requires sophisticated neurointerventional techniques. The purpose of this study was to develop a simple and cost-effective AVM animal model that does not require additional endovascular techniques. METHODS: A surgical anastomosis was created in seven sheep between the common carotid artery and the ipsilateral jugular vein, followed by ligation of the jugular vein above the anastomosis and of the proximal common carotid artery below the anastomosis. The anastomosis was created on the left side in four animals and on the right side in three. Cerebral angiography from the contralateral carotid artery was performed before and immediately after surgery to delineate the relevant cerebral vascular anatomy and to determine the direction of blood flow. RESULTS: An angiographic appearance simulating an AVM was found in all the animals. The ramus anastomoticus and arteria anastomotica functioned as the feeding vessels to the rete mirabile, which represented the nidus in our model, and to the jugular vein, which represented the draining vein from the malformation. Extensive collateral flow through the rete mirabile into the distal segment of the external carotid artery above the ligature was observed angiographically, with retrograde flow through the surgical anastomosis into the jugular vein. CONCLUSION: A simple surgically created experimental model for cerebral AVMs was developed in sheep without the need for additional complex endovascular catheter manipulations of intracranial branches. Such an animal model can substantially reduce the cost of research and training in the neurointerventional or radiosurgical management of AVMs.

Anastomosis, Surgical↗
PubMed1998

Beta-chemokine expression and distribution in paraffin-embedded transplant renal biopsy sections: analysis by scanning laser confocal microscopy.

Previous immunohistochemical and in situ hybridisation studies have shown that, in tubulitis associated with acute cellular rejection of human renal allografts, intratubular T cells proliferate and are fully activated in situ. In the immunohistochemical study reported here we have attempted to establish some understanding of the involvement of the beta-chemokines RANTES, MCP-1, MIP-1alpha and MIP-1beta in recruiting T cells to the intratubular site. Paraffin-embedded routine biopsy sections were treated for conventional indirect immunofluorescence to detect the selected chemokines. Scanning laser confocal microscopy was used to provide a measure of fluorescence intensity resulting from binding of FITC-labelled secondary antibody. Cells expressing chemokines could be identified and, within the limits of the staining method, it was possible to obtain a semi-quantitative assessment of individual chemokine activity at different points in biopsy sections by constructing a profile of fluorescence intensity. High concentrations of chemokines (especially RANTES, MIP-1beta and/or MIP-1alpha) were localised to the basolateral surface of tubular epithelial cells (TEC). MCP-1 was also consistently present but at a lower level than RANTES except in one case identified as BANFF category 3. There was diffuse distribution of chemokines in the interstitial matrix and low intensity fluorescence outlined some endothelial cells of peritubular venules and interstitial fibroblast-like cells. Our results suggest a mechanism for specific chemotactic recruitment of inflammatory cells by TEC-produced chemokines.

Biopsy↗
PubMed1997

A c-Cbl yeast two hybrid screen reveals interactions with 14-3-3 isoforms and cytoskeletal components.

The protein product of c-cbl proto-oncogene is known to interact with several proteins, including Grb2, Crk and PI3 kinase, and is thought to regulate signalling by many cell surface receptors. The precise function of c-Cbl in these pathways is not clear, although a genetic analysis in Caenorhabditis elegans suggests that c-Cbl is a negative regulator of the epidermal growth factor receptor. Here we describe a yeast two hybrid screen performed with c-Cbl in an attempt to further elucidate its role in signal transduction. The screen identified interactions involving c-Cbl and two 14-3-3 isoforms, cytokeratin 18, human unconventional myosin IC, and a recently identified SH3 domain containing protein, SH3 P17. We have used the yeast two hybrid assay to localise regions of c-Cbl required for its interaction with each of the proteins. Interaction with 14-3-3 is demonstrated in mammalian cell extracts.

14-3-3 Proteins↗
PubMed1997

Infestation of sheep dung by nematophagous fungi and implications for the control of free-living stages of gastro-intestinal nematodes.

A field trial was conducted to assess the rate at which dung becomes infested by fungi which parasitise nematodes (nematophagous fungi) after deposition. Sheep dung was placed on field plots of bare ground, ryegrass (Lolium perenne), browntop (Agrostis capillaris) and white clover (Trifolium repens) in summer (February) and autumn (April), and subsamples were examined at intervals for the presence of nematophagous fungi. Nematophagous fungi occurred in 71% of 129 samples recovered in February and 57% of 58 samples recovered in April. Arthrobotrys oligospora, Monacrosporium candidum and Nematoctonus spp. were the most frequently isolated nematode-trapping fungi in both seasons. The endoparasitic nematophagous fungus Harposporium leptospira also occurred frequently in dung deposited in February, but not April. Fungi entered dung quickly, with 83% and 58% of dung samples containing nematophagous fungi at 3 days after deposition in February and April, respectively. The percentage of dung infested by nematophagous fungi on plots of bare ground, ryegrass, white clover and browntop was 76%, 75%, 61% and 55%, respectively. Results suggest that a number of species of nematophagous fungi are able to enter dung soon after deposition on a variety of types of ground cover.

Animals↗
PubMed1996

Renal allograft rejection--in situ demonstration of cytotoxic intratubular cells.

A nonisotopic in situ hybridization method to detect perforin mRNA was developed in cytospin preparations of IL-2-stimulated normal human lymphocytes and applied to formalin-fixed acutely rejected renal transplant material. Individual cells expressing perforin mRNA were localized in severely damaged tubular areas, and a number of these cells appeared to be located inside the tubular basement membrane in close association with tubular epithelial cells. Immunoperoxidase staining in acetone-fixed cryostat sections of acutely rejected kidney confirmed that a considerable proportion of infiltrating cells was CD8+; many of these were in an intratubular location. In addition, perforin protein was identified in individual cells in similar locations to perforin mRNA-positive cells. Again, some intratubular cells were identified. Our findings illustrate that these cells can be fully activated with definite cytotoxic potential. Previously we have demonstrated that T lymphocytes proliferate within the tubular compartment during tubulitis, a characteristic condition in acute renal allograft rejection, and that there is associated tubular epithelial cell proliferation. In this study we think that we have further clarified the consequences of invasion of tubules by lymphoid cells. Our in situ hybridization method in rapid and convenient and may be applied to archival material.

Acute Disease↗
PubMed1995

In situ lymphoproliferation in renal transplant biopsies.

A double immunohistochemical labelling procedure in paraffin-embedded renal tissue is reported in which CD3 was targeted as a T cell marker and Ki67 as a marker of cell proliferation. Proliferating and quiescent T cells were unequivocally identified in situ, and their precise location within the kidney was clarified by the use of periodic acid-Schiff counterstaining to outline the basement membranes. Proliferating tubular epithelial cells were also clearly identified. The results showed that T lymphocytes proliferate within the tubular compartment during acute renal allograft rejection. Preliminary evaluation of the method in routine transplant biopsies indicated significant correlations between histologically defined rejection grade and mean intratubular T lymphocytes per tubular cross section and between proliferation of tubular epithelial cells and of intratubular T lymphocytes. The associated tubular epithelial cell proliferation may be a response to local damage.

Antigens, Differentiation↗
PubMed1995

How midwives identify women as aboriginal or Torres Strait Islanders.

At the present time no reliable information is available about how midwives actually decide to record a person as Aboriginal or Torres Strait islander on the Perinatal Morbidity Statistics form. In 1993, Koori Health in the Department of Health and Community Services asked the Perinatal Data Collection Unit to undertake a study to determine how midwives make this decision. The study was conducted in seven country and city hospitals and two universities from August to December 1993. The hospitals ranged in size from 149 to 2359 births per year. During a routine education session the midwives were invited to take part in a focus group discussing 'Aboriginality'. Fifty-four midwives were involved in the study. Most mothers were not asked if they identified as 'Aboriginal or Torres Strait Islanders'. Midwives did ask women who they thought were 'Aboriginal' by appearance. Most midwives did not ask about 'Aboriginality' because they felt uncomfortable asking. They felt uncomfortable because they felt that both Aboriginal and non-Aboriginal women would feel ill at ease when asked if they identified as Aboriginal or Torres Strait Islanders. There were many reasons for this but they included negative perceptions of Aboriginal women. Some midwives made discriminatory comments. The conclusions of the study are that midwives need to know the reasons why they are requested to ask all women if they identify as Aboriginal or Torres Strait Islanders. Major barriers are often based on poor knowledge and understanding of definitions and issues. There was strong evidence of the existence of underlying beliefs and perceptions about Aboriginal people which 'inhibit' midwives from complying with the Data Collection Unit's explicit advice on the collection of this information.

Attitude of Health Personnel↗
PubMed1995

Poor knowledge and misunderstandings: perinatal data validity and work place change in midwifery.

The purpose of this study was to improve the validity of data by empowering midwives to change inefficient work place practices. An easily accessible package was designed to enable midwives to compare how closely the information they recorded on the original perinatal morbidity statistics form corresponds with information recorded in the medical record: 37 hospitals validated 2197 medical records. The results showed that whilst most information was recorded reliably, some items caused problems for those completing the form. The findings encouraged midwives to change inefficient data collection practices. The project has improved the validity of data plus reduced the workloads of hospitals and the Perinatal Data Collection Unit with respect to queried items.

Clinical Competence↗
PubMed1995

Anti-glomerular basement membrane glomerulonephritis in the mouse: the role of macrophages.

An immunohistochemical study was undertaken on fixed, paraffin-embedded mouse kidney in order to elucidate the role and significance of infiltrating macrophages in a mouse model of anti-glomerular basement membrane glomerulonephritis (anti-GBM GN). Tissue was available representing the full gamut of histological features seen in this model. The mouse macrophage-specific antigen F4/80 was detected in tissue sections of glomerulonephritic kidney and the pattern and extent of staining was compared with normal mouse kidney. In glomerulonephritic kidney, an increase in the number of F4/80-positive cells was evident in close proximity to and surrounding Bowman's capsule of those glomeruli which were severely damaged, with extensive fibrin deposition and well developed cellular crescents. F4/80-positive cells did not feature in the glomerular tuft or in the region of the parietal epithelium of Bowman's capsule even when extensive cellular crescents were present. Breaks in Bowman's capsule were not demonstrated. We conclude that F4/80-positive macrophages are not a major constitutive cell type of developing crescents in this mouse model of anti-GBM GN but, by virtue of their peri-glomerular localization, may be involved in the destructive process, perhaps producing signalling molecules which contribute to the inflammatory reaction.

Animals↗
PubMed1994

In vitro bromodeoxyuridine labelling of renal biopsy specimens: correlation between labelling indices and tubular damage.

AIMS: To examine the correlation between bromodeoxyuridine (BrdU) labelling indices (LI) and tubular damage in renal biopsy specimens; to evaluate the diagnostic and prognostic potential of measuring cell proliferation in a variety of renal lesions. METHODS: In vitro BrdU labelling of renal biopsy specimens was undertaken and labelled cells were detected in routinely fixed, paraffin wax embedded sections by immunohistochemistry. The BrdU LI were calculated as percentages for the three types of tubular cells--proximal and distal convoluted tubules and medulla (LI/PCT, LI/DCT, LI/Med)--and a total tubular BrdU LI (LI/Tub) was also calculated for each biopsy specimen. Histological features indicative of tubular damage were also scored and a total tubular damage score obtained for each biopsy specimen. RESULTS: The one hour labelling process did not affect tissue morphology or impede subsequent diagnosis. Four biopsy specimens were obtained from three renal transplant recipients. Diagnosis of 19 non-transplant biopsy specimens revealed a variety of renal lesions. Total tubular damage scores ranged from 0 to 25 and the LI/Tub ranged from 0 to 3.68% in all 23 biopsy specimens. Analyses of variance showed highly significant correlations between the total tubular damage score and both LI/Tub (p = 0.004) and LI/PCT (p = 0.004); a weaker correlation was found between the total tubular damage score and LI/DCT (p = 0.013). CONCLUSIONS: A correlation was found between tubular damage and BrdU LI. This was most clearly seen in the proximal tubules. However, as the study was limited to a few examples of specific forms of glomerular or interstitial disease, firm conclusions about the value of BrdU labelling in routine diagnosis and prognosis could not be drawn.

Biopsy, Needle↗
PubMed1993

c-fos antisense generates apomorphine and amphetamine-induced rotation.

Sodium pentobarbital anaesthetized rats were injected ipsilaterally with an antisense oligonucleotide to c-fos and contralaterally with a sense of oligonucleotide to c-fos in the striatum. Ten hours later they were injected with amphetamine or apomorphine and their behaviour was observed for a further 2 h at which time they were overdosed with anaesthetic and their brains were removed, frozen and processed for Fos and Jun B immunohistochemistry. Rats showed amphetamine- and apomorphine-induced rotation towards the antisense injected striatum. The antisense oligonucleotide also strongly inhibited the amphetamine-induced expression of c-Fos and Jun B in striatal neurones. These results suggest that antisense to c-fos produces a biochemical change in the injected striatum that then, 10 h later, blocks amphetamine- and apomorphine-induced behavioural and biochemical effects.

Amphetamine↗
PubMed1993

Tissue distribution of amyloid P component as defined by a monoclonal antibody produced by immunization with human glomerular basement membranes.

A monoclonal antibody reactive against amyloid P component (NCL-AMP) has been developed following immunization of mice with partially-purified human glomerular basement membranes (GBM) and standard hybridization and cloning techniques. The antibody reactivity was evaluated by enzyme-linked immunosorbent assay (ELISA) and by the indirect immunoperoxidase technique on sections of frozen and fixed human kidney and other tissues. The distribution of amyloid P component in various normal tissues is described and the possible co-localization with the Goodpasture antigen is discussed. In addition, the suitability of the antibody for detection of amyloid deposits in renal amyloidosis is demonstrated and its potential for use in other pathological conditions is considered.

Animals↗
PubMed1993

Anti-glomerular basement membrane glomerulonephritis (anti-GBM GN) in the mouse: BrdU-labelling indices and histological damage.

In-vivo BrdU incorporation and visualization by immunohistochemistry, previously reported in normal mouse kidney, were applied to a mouse model of anti-GBM GN, induced by immunization with rabbit anti-mouse GBM antiserum, to assess the contribution of capsular cell proliferation in the development of crescents. A significant increase (P = 0.003) in the BrdU-labelling index (LI) for capsular cells was observed, as compared to normal mice (5.76 +/- 1.1 vs 0.70% +/- 0.12%). Elevated LI were also observed for tuft and tubular cells but these increases were not statistically significant. It was concluded that, in this model, capsular cell proliferation is a major contributory factor to the formation of cellular crescents. In addition, other pathological features, indicative of glomerular damage, were assessed semi-quantitatively alongside numbers of labelled capsular cells per glomerulus. It was found that podocyte vacuolation is strongly associated with, and may precede, proliferation, suggesting some common causative factor. Fibrin, when present, was confined within the tuft capillary loops and was only weakly associated with either podocyte vacuolation or capsular cell proliferation. It was concluded that this protein does not play a major role in the initiation of pathological damage. Finally, glomerular lesions were found to be randomly distributed. Thus, the idea of intraglomerular signalling, resulting in 'clustering' of damaged glomeruli, is not supported.

Animals↗
PubMed1990

In vivo bromodeoxyuridine incorporation in normal mouse kidney: immunohistochemical detection and measurement of labelling indices.

A method is reported for in vivo bromodeoxyuridine incorporation in mice and its subsequent visualization in kidney by immunohistochemistry. Following formal-sublimate fixation of the kidney, bromodeoxyuridine labelled nuclei were detected in paraffin sections with a monoclonal antibody and visualized by an immunoperoxidase technique. This rapid and unequivocal method was used to measure labelling indices in tubules, glomerular tuft and Bowman's capsule in normal male T70 (Beige) mice, at intervals up to 72h after labelling. Significant differences were found between the labelling indices of these three populations of cells, which appeared to show different cell kinetic behaviour.

Animals↗