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Biomedical subjects

P Gibbs

Publications and source records attributed to P Gibbs.

At least 73 records · Page 4Linked to original sources
PubMed1998

Split liver transplantation: King's College Hospital experience.

BACKGROUND: The purpose of split liver transplantation is to increase the source of pediatric grafts without compromising the adult donor pool. Early results have been discouraging because of technical complications and selection of poor risk patients. METHODS: The results of a single center experience of 41 split liver transplantations were analyzed. Patient and graft survival and complications related to the technique were analyzed. RESULTS: Patient and graft survival for the whole group was 90% and 88% respectively at a median follow up of 12 months (range 6-70 months). Patient and graft survival for the right lobe graft was 95% and the left lateral segment 86% and 82% respectively. Four patients died, of which two of the patients were first two splits following technical complications. Two others died, one from cerebral lymphoma and the other of multiorgan failure secondary to sepsis. One patient has been retransplanted for chronic biliary sepsis. CONCLUSION: Split liver transplantation has now become an acceptable treatment option for both adult and pediatric recipients with end stage liver disease. Right lobe recipients are not disadvantaged by the procedure. Good results can be achieved with better patient selection and by the use of good quality organs.

Adolescent↗
PubMed1998

Effects of oncostatin M and tamoxifen on human melanoma cells.

New agents are required in the treatment of malignant melanoma, to be used alone or in combination with established therapies. Oncostatin M (OSM), a member of the gp130 family of cytokines, has previously been shown to inhibit the growth of melanoma cell lines. Tamoxifen (TAM) is widely used in the treatment of melanoma, typically in combination with chemo- and/or immunotherapy. A component of the antitumour activity of TAM is via modulation of transforming growth factor-beta (TGF beta) which has previously been shown to be synergistic with OSM in vitro. To further investigate the clinical potential of OSM, alone and in combination with TAM, set concentrations of each were added to nine fresh and two well-established melanoma cell lines. The proliferation of seven of the 11 cell lines was inhibited by OSM, while two were unresponsive at the dose range tested. Of particular interest was the finding that the growth of two of the cell lines was significantly stimulated at low doses of OSM. The combination of OSM with TAM produced widely divergent results, most frequently resembling the effects of OSM alone. No synergism between the two was evident in any of the cell lines tested. Our results indicate that a combination of OSM and TAM in clinical trials needs further evaluation before it can be recommended. Furthermore, while OSM alone may be useful in the treatment of melanoma, this may be complicated by the possibility of stimulating tumour growth in some instances.

Antineoplastic Agents↗
PubMed1998

Primary breast abnormalities: selective pixel sampling on dynamic gadolinium-enhanced MR images.

PURPOSE: To evaluate a region-of-interest (ROI) analytic method that involves selective sampling of pixels within predetermined ranges of contrast material enhancement values ("thresholding") on magnetic resonance (MR) images of primary breast abnormalities. MATERIALS AND METHODS: Dynamic gadolinium-enhanced MR images were obtained in 105 women. ROIs were drawn to outline the full extent of lesions. Relative signal intensity increase was determined on a pixel-by-pixel basis on 1- and 2-minute postcontrast images, as was the maximum relative signal intensity increase. Thresholding was used to analyze each ROI, with the upper boundary defined by the highest pixel value and lower boundaries of 0%-100%. RESULTS: Seventy-one invasive carcinomas and 37 benign lesions were analyzed. Narrower thresholding (i.e., larger percentage) resulted in an increase in all enhancement ratios (P < .0005). The enhancement ratio on 1-minute postcontrast images differed between benign lesions and carcinomas (P < .0005), but there were no significant differences in 2-minute and maximum ratios. Mean enhancement differences between benign and malignant lesions increased with narrower thresholding, but variability also increased linearly. Results of receiver operating characteristic analysis showed that thresholding did not affect the diagnostic usefulness of enhancement ratios. CONCLUSION: Contrary to current opinion, selective sampling of the most enhancing areas of breast abnormalities may not provide any diagnostic advantage over the use of easily drawn, lesion-encompassing ROIs.

Biopsy↗
PubMed1998

Radiotherapy treatment planning of brain tumours using MRI alone.

MRI of the brain can provide images of very high quality revealing detailed information especially concerning the extent of abnormalities. As such MRI has great potential in the radiotherapy (RT) planning of brain tumours. However MRI has rarely been used alone as the basis for treatment planning primarily due to concern over potential geometric distortions. Treatment planning using MRI has therefore usually been carried out in conjunction with CT images. This work demonstrates that geometric distortions can be minimized by using a relatively small field-of-view, an increased receiver bandwidth, and a fast spin echo acquisition sequence, and that it is thus possible to perform RT planning using MRI.

Brain Neoplasms↗
PubMed1998

Periodontitis: a risk factor for coronary heart disease?

This paper evaluates the current information on the relationship between oral disease (specifically periodontitis) and atherosclerosis/coronary heart disease (CHD) to determine whether the information is sufficient to conclude that periodontitis is a risk factor for atherosclerosis/CHD. As background for this evaluation, the term "risk factor" is defined, and the 3 criteria used to establish exposures as risk factors are reviewed. In addition, epidemiologic criteria for defining an exposure as causal are presented. The available evidence then is evaluated according to the criteria for causality, which are extensions of the criteria for establishing a risk factor. This review is done in the context of the relationship between atherosclerosis/CHD and inflammation. A number of findings are briefly reviewed that link inflammation and atherosclerosis/CHD, such as: 1) prior flu-like symptoms were more common in cases of myocardial infarction than in concurrently sampled controls; 2) high levels of cytomegalovirus antibody titers were associated with elevated carotid intimal-medial wall thickness 18 years later; 3) prior infection with cytomegalovirus was a strong independent risk factor for restenosis after coronary atherectomy; 4) dental infections were more common in cases of cerebral infarction compared to community controls matched on age and sex; and 5) the gingival index was significantly correlated with fibrinogen and white cell counts in periodontal patients and controls, adjusted for age, smoking, and socioeconomic status. Three case-control studies and 5 longitudinal studies investigating the relationship between dental conditions and atherosclerosis/CHD are reviewed in terms of strength of associations, consistency of associations, specificity. of associations, time sequence between exposure and outcome, and degree of exposure and outcome. Related to the last criterion, new findings are presented which indicate that the extent of the periodontal infection, a measure reflecting microbial burden, also is related to onset of new CHD events. Our previously published model describing the potential biological mechanisms underlying the associations found is reviewed. This model places the associations into a context of an intrinsic or acquired hyperinflammatory monocyte trait that results in a more intense inflammatory response to lipopolysaccharide (LPS) challenges, such as periodontal infections. This hyperinflammatory response may promote atheroma formation and thromboembolic events. finally, new findings from ongoing animal studies are presented, indicating that high fat diets in atherosclerotic-susceptible mice induce greater inflammatory responses to Porphyromonas gingivalis challenges. We conclude that the available evidence does allow an interpretation of periodontitis being a risk factor for atherosclerosis/CHD. This conclusion, however. is made with some qualifications. While the associations found across a wide variety of subjects are remarkably consistent, for the most part they are represented by incidence odds ratios around 2.0. While this level of association would result in oral conditions contributing to a large number of CHD cases, it is possible that associations of this magnitude are due to bias in the study designs. In addition, some studies report that periodontitis is associated with all-cause mortality and low birth weight infants. These multiple associations detract from the credibility of periodontitis as a risk factor, as specificity of association is more often related to causality. However, all-cause mortality may largely be driven by mortality from cardiovascular events: and some exposures, such as smoking. are indeed risk factors for multiple conditions. On the other hand, current findings regarding the associations between oral conditions and atherosclerosis/CHD imply that the criteria for causality may be met in the not-too-distant future.

Animals↗
PubMed1997

Cavocaval liver transplantation without venovenous bypass and without temporary portocaval shunting: the ideal technique for adult liver grafting?

The influence of the implantation technique on the outcome was studied prospectively in a series of 116 consecutive adult patients undergoing primary liver transplantation during the period January 1991-June 1994. Thirty-eight patients (32.8%; group 1) underwent classical orthotopic liver transplantation (OLT) with replacement of the recipient's inferior vena cava (R-IVC) and with venovenous bypass (VVB). Thirty-nine patients (33.56%) had a piggy-back OLT with preservation of the R-IVC (group 2); bypass was used in 17 of them (43.6%) because of poor hemodynamic tolerance of R-IVC occlusion. Thirty-nine patients (33.6%) had OLT without VVB and with side-to-side cavocaval anastomosis (group 3). The three techniques were performed irrespective of the anatomical situation and of the status of the recipient at the time of transplantation. The following parameters were assessed in all patients: implantation time, blood product use, morbidity (e.g., hemorrhagic, thoracic, gastrointestinal, neurological, and renal complications), and outcome. Thirty-one patients underwent detailed intraoperative hemodynamic assessment. The early (< 3 months) post-transplant mortality of 10.3% (12/116 patients) was unrelated to the implantation technique. Group 3 had a significantly shorter mean implantation time, a reduced need for intraoperative blood products, and a lower rate of reoperation due to intra-abdominal bleeding. After excluding two immediate perioperative deaths and eight patients requiring early retransplantation because of primary nonfunction, the frequency of immediate extubation was significantly higher in group 3. Detailed hemodynamic assessment did not show a difference between 6 group 1 patients and 17 group 3 patients, indicating that partial lateral clamping of the IVC fulfills the function of venous bypass. Similar results were obtained in 6 group 2 patients who did not have IVC occlusion. Cavocaval OLT has become our preferred method of liver implantation. It allows the transplantation to be performed without VVB, regardless of the anatomical situation and of the condition of the patient at the time of transplantation. Moreover, it avoids all of the potential complications and costs of VVB.

Adult↗
PubMed1997

Hepatic transplantation in children under 3 months of age: a single centre's experience.

Liver transplantation in neonates represents a major medical and technical challenge particularly in babies weighing less than 5 kg. The authors report the experience of 10 liver transplants in 9 babies (6 boys and 3 girls), mean age, 6 weeks (range, 2 to 11); median weight, 3.7 kg (range, 2.4 to 5). All had fulminant hepatic failure caused by neonatal haemochromatosis (n = 3), non-A non-B hepatitis (n = 3), total parenteral nutrition induced (n = 1), hepatitis B (n = 1), and hepatic haemangio-endothelioma (n = 1). One child underwent retransplantation for hepatic artery thrombosis. Immunosuppression was by Cyclosporine A-based triple therapy in all cases. All received a reduced size graft consisting of left lobe (n = 1), left lateral segment (n = 6) and monosegment III (n = 3). In nine cases the donor hepatic artery was anastomosed to an iliac artery conduit from the infrarenal aorta, and a Roux loop was used for bile duct reconstruction. Primary abdominal wound closure was possible in six patients, skin closure alone in one, and a silastic patch was used in three. Complications included infection (n = 5), bowel perforation (n = 2), diaphragmatic perforation (n = 2), bile leak (n = 1), hepatic artery thrombosis (n = 1), and portal vein thrombosis (n = 1). None of the babies experienced acute rejection. Currently five of the nine recipients are alive with good graft function at a mean follow-up of 22 months (range, 5 to 58). Of the four deaths, two were related to infection (one in combination with portal vein thrombosis), one to multiorgan failure and fluid overload, and one to early graft dysfunction and sepsis after undergoing retransplantation for hepatic artery thrombosis. From our experience liver transplantation offers a promising option for the treatment of severe liver disease in children less than 3 months old.

Age Factors↗
PubMed1997

Hirschsprung's disease: a 20-year experience.

During the period from 1972 to 1992, 59 children received surgical treatment at the University of Louvain Medical School for biopsy-proven Hirschsprung's disease (HD). The extent of aganglionosis was as follows: short segment restricted to the rectosigmoid or descending colon (n = 44, 75%); long segment (n = 9,15%); ultra-short segment (n = 3, 5%); unknown length because of death without autopsy (n = 3, 5%). The median age at operation was 7 months for short-segment disease compared with 14 months for those with long-segment disease. Surgical procedures used for short-segment disease were Swenson with colostomy (n = 16), Swenson-Pellerin without colostomy (n = 27), Duhamel (n = 1), and for long-segment disease were Martin (n = 3), Swenson-Deloyers (n = 2), Swenson-Boley (n = 2) and ileostomy only in = 2). Lynn's sphincteromyotomy was performed in the three ultra-short cases. There were six deaths (10%) at a median age of 86 days (range, 28 to 1545 days), three had long-segment disease, and the others were not classified because of death before curative surgery. Enterocolitis (EC) was the most common cause of death (five cases) and was also the major source of morbidity after curative surgery (12 of 44, 27%) in short-segment patients, three of seven (43%) in long-segment patients. The functional success of the procedure was evaluated in 70% of the surviving patients (37 of 53; mean follow-up, 8.7 years; range, 1.2 to 21.5), using a novel semiquantitative scoring system, specifically designed for children who have HD. This system assesses normal stool evacuation, abdominal distention, soiling, and severe incontinence. The results were compared with those from a population of 39 healthy children and adolescents and demonstrated progressive improvement in function during childhood and adolescence (P = .04) for patients treated for short-segment disease. However, function was found to be consistently poorer in all age groups when compared with healthy controls (5 to 10 years, P < .01; 10 to 15 years, P < .05; > 15 years, P < .01).

Enterocolitis↗
PubMed1997

Immunogenicity of biliary epithelium: study of the adhesive interaction with lymphocytes.

BACKGROUND & AIMS: Intrahepatic bile ducts express a range of lymphocyte adhesion molecules during episodes of inflammation. This may contribute to the susceptibility of biliary epithelium to immunologic damage during liver allograft rejection, graft-versus-host disease, and primary biliary cirrhosis. However, no previous study has shown that these adhesion molecules are functional. The aim of this study was to define the molecular basis of lymphoepithelial interactions within the intrahepatic bile ducts. METHODS: Human intrahepatic biliary epithelial cells (HIBECs) were cultured, and their interaction with resting and activated lymphocytes was studied using a flow-cytometric assay that allowed characterization of the adherent cells and functional investigation of individual adhesive interactions. The capacity of adherent cytotoxic lymphoid cells to damage HIBEC was studied using a standard 51Cr release assay. RESULTS: Allogeneic lymphocytes were bound by HIBECs; this adherence was increased by activation of either participating cell type. Cells with cytotoxic capacity were bound preferentially. At least 50% of the overall adhesion was dependent on lymphocyte function-associated antigen 1. Cytotoxicity assays showed that HIBECs were susceptible to lysis by lymphokine-activated natural killer cells. CONCLUSIONS: This study shows that the adhesion molecules expressed by HIBECs are functional and necessary for the activity of cytotoxic effector lymphocytes.

Bile Ducts, Intrahepatic↗
PubMed1997

Immunologic responses to vaccinia vaccines administered by different parenteral routes.

To develop a less reactogenic but equally immunogenic vaccine, this study of 91 human volunteers compared the safety and immunogenic potency of a new, cell culture-derived vaccinia virus vaccine administered intradermally and intramuscularly with the licensed vaccinia vaccine administered by scarification. Cutaneous pox lesions developed in a higher proportion of scarification vaccinees. Scarification and intradermal vaccine recipients who developed cutaneous pox lesions had more local reactions but also achieved significantly higher cell-mediated and neutralizing antibody responses than those who did not develop pox lesions. Although less reactogenic, intradermal or intramuscular administration of vaccinia vaccine without the concomitant development of a cutaneous pox lesion induced lower immune responses.

Antibodies, Viral↗
PubMed1996

Development of a flow cytometric assay to quantify lymphocyte adhesion to cytokine-stimulated human endothelial and biliary epithelial cells.

The adhesive interaction between T lymphocytes and parenchymal cells is of importance for many processes of the cellular immune response. This adhesion is regulated by the activation status of the T cell and by cytokines in the microenvironment which can alter adhesion molecule expression by endothelial and epithelial cells. In this study results from an isotopic adhesion assay were compared with those from a flow cytometric assay in order to determine which was most appropriate for the investigation of lymphocyte adhesion to human umbilical vein endothelial cells (HUVEC) and intrahepatic biliary epithelial cells (HIBEC). Treatment of both these cell types with the proinflammatory cytokines interferon-gamma (IFN-gamma) or tumour necrosis factor-alpha (TNF-alpha) significantly upregulated expression of intercellular adhesion molecule-1 (ICAM-1). Treatment with TNF-alpha also induced endothelial cells to express vascular cell adhesion molecule-1 (VCAM-1). The isotopic assay demonstrated increased adhesion of lymphoblasts to HUVEC which had been stimulated with cytokines for 15 h but failed to detect major changes in adhesion following 72 h of cytokine treatment of HUVEC or HIBEC. However, the flow cytometric assay reproducibly demonstrated increased adhesion following cytokine treatment for both these time periods; these increases corresponded with the changes in adhesion molecule expression by cytokine-stimulated HUVEC and HIBEC targets. The differences in apparent adhesion measured by the two assays after cytokine stimulation for 72 h may be explained by cytokine-induced changes in the morphology and confluency of cultured cells. Results of the isotopic assay are proportional to the total number of lymphoid cells bound by the cultured target cells and will be distorted by changes in effective target cell area. The flow cytometric assay measures the mean number of lymphoid cells bound by each target cell and is independent of the total binding area. It is concluded that the flow cytometric assay is more suitable than the isotopic technique for following time-dependent changes in the adhesion of leukocytes to cytokine-stimulated target cells.

Bile Ducts, Intrahepatic↗
PubMed1996

Detailed modified technique for safer harvesting and preparation of liver graft in the rat.

Liver procurement and preparation for orthotopic liver transplantation (OLT) in the rat is the first stage for beginners aiming to acquire mastery of this model. It requires extensive and precise dissection in which each detail must provide security for the procurement and perfection for the future graft. Many technical details, "tricks and secrets," remain known only by expert teams, so that the learning phase can be long or unsuccessful if a period in such a team is not possible. We describe this procedure in great detail, including many improvements to the original technique. Complete illustration is provided to enable an easier appreciation of what remains the critical first part of the most difficult transplant model to perform in the rat.

Animals↗
PubMed1996

Hepatic allograft rejection: regulation of the immunogenicity of human intrahepatic biliary epithelial cells.

Intrahepatic biliary epithelial cells were immunomagnetically purified from specimens of disaggregated human liver and were propagated in vitro. After three passes in culture, the cells were shown to be over 85% pure with contaminating leukocytes and endothelial cells constituting less than 2% of the population. Sensitive flow microfluorimetric analysis was performed after immunofluorescence labeling to quantify expression of both class 1 and class II major histocompatibility (MHC) antigens and the adhesion molecules intercellular adhesion molecule-1 (ICAM-1), vascular cell adhesion molecule-1 (VCAM-1), and lymphocyte function-associated antigen-3 (LFA-3). It was shown that resting human intrahepatic biliary epithelial cells (HIBEC) expressed class 1 MHC antigens, ICAM-1, and relatively low levels of LFA-3. Stimulation with tumour necrosis factor-alpha (TNF-alpha) upregulated expression of ICAM-1, whereas Interferon-gamma (IFN-gamma) and a combination of IFN-gamma and TNF-alpha upregulated class I MHC antigens and ICAM-1 and induced class II MHC molecules. The level of expression of MHC antigens and of ICAM-1 and LFA-3 after stimulation of HIBEC with combined IFN-gamma and TNF-alpha was comparable with the expression of these antigens by an Epstein-Barr virus-transformed B-cell line. The phenotypic similarity between cytokine-stimulated HIBEC and a known antigen presenting cell is consistent with a potential role for biliary epithelial cells in antigen presentation.

Bile Ducts↗
PubMed1996

Tumour volume determination from MR images by morphological segmentation.

Accurate tumour volume measurement from MR images requires some form of objective image segmentation, and therefore a certain degree of automation. Manual methods of separating data according to the various tissue types which they are thought to represent are inherently prone to operator subjectivity and can be very time consuming. A segmentation procedure based on morphological edge detection and region growing has been implemented and tested on a phantom of known adjustable volume. Comparisons have been made with a traditional data thresholding procedure for the determination of tumour volumes on a set of patients with intracerebral glioma. The two methods are shown to give similar results, with the morphological segmentation procedure having the advantages of being automated and faster.

Brain Neoplasms↗
PubMed1996

Improved peripheral MR angiography with temperature regulation in healthy patients.

Peripheral magnetic resonance (MR) angiography was performed in eight volunteers, with a temperature-controlled water blanket. After warming of the right foot, unobserved vessels became conspicuous in all patients: Average increase in signal intensity was nearly twofold in the major artery and vein depicted. A similar improvement was observed in an examination in one patient with diabetes. Peripheral MR angiography performed after warming provided additional diagnostic information.

Adult↗