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Biomedical subjects

P A Lear

Publications and source records attributed to P A Lear.

At least 19 recordsLinked to original sources
PubMed2006

From meeting presentation to peer-review publication--a UK review.

INTRODUCTION: Annual academic surgical meetings provide a forum for the discussion of research. For the wide-spread dissemination of this information, peer-reviewed publication is required. The aim of this study was to compare the amount of presentations which go on to publication from 4 UK-based surgical meetings. MATERIALS AND METHODS: We determined whether a presentation had led to a successful publication using PubMed, a median of 28 months following each meeting. We compared the ASGBI publication rate with the meetings of the Vascular Surgical Society (VSSGBI), the Association of Coloproctology of Great Britain and Ireland (ACPGBI) and the British Transplantation Society (BTS). We also compared the median impact factor of journals used. RESULTS: The ASGBI and BTS had a similar rate of presentations resulting in publication, with 35% and 36% at 2 years, respectively. The VSS had a significantly greater proportion of presentations resulting in publication (54% at 2 years; P = 0.004), whilst the ACPGBI had significant fewer (24% at 2 years; P = 0.006). There was no difference in the median impact factors of the journals used between the meetings (Kruskal Wallis P = 0.883). CONCLUSIONS: There is a significant variation between meetings in terms of turning presentations into publications. However, the majority of abstracts have still not been fully published within 2 years of presentation at the meeting.

Bibliometrics↗
PubMed2005

Porcine dermal collagen graft in pediatric renal transplantation.

Successful closure of the anterior abdominal wall in infants following renal transplantation of adult organs may present a challenging dilemma to the transplant surgeon. Restricted volume of the recipient abdominal cavity and size discrepancy of donor adult kidney may lead to graft compromise. Pressure on the graft may be exacerbated further in the postoperative period by oedema that may lead to abdominal compartment syndrome. Donor/recipient size disparity remains the major obstacle in infant renal transplantation. We describe the use of a porcine collagen graft to facilitate closure of the abdominal wall following intra-peritoneal transplantation of an adult cadaveric kidney.

Abdominal Wall↗
PubMed2005

Intestinal adaptation after massive intestinal resection.

Patients with short bowel syndrome require long term parenteral nutrition support. However, after massive intestinal resection the intestine undergoes adaptation and nutritional autonomy may be obtained. Given that the complications of parenteral nutrition may be life threatening or result in treatment failure and the need for intestinal transplantation, a more attractive option is to wean patients off nutrition support by optimising the adaptive process. The article examines the evidence that after extensive small bowel resection adaptation occurs in humans and focuses on the factors that influence adaptation and the strategies that have been used to optimise this process. The review is based on an English language Medline search with secondary references obtained from key articles. There is evidence that adaptation occurs in humans. Adaptation is a complex process that results in response to nutrient and non-nutrient stimuli. Successful and reproducible strategies to improve adaptation remain elusive despite an abundance of experimental data. Nevertheless given the low patient survival and quality of life associated with other treatments for irreversible intestinal failure it is imperative that clinical research continues into the optimisation of the adaptation.

Adaptation, Physiological↗
PubMed2004

The impact of training on outcomes in primary vascular access surgery.

BACKGROUND: There is evidence that the outcome of arteriovenous fistula surgery is dependent on the surgeon performing the operation. Vascular access surgery provides excellent technical training for surgical trainees. The effect of surgical trainees on the outcome of fistulas was evaluated. METHODS: The grade of the main operator for all first attempted (primary) upper limb arteriovenous fistulas, between February 1998 and August 2001, was identified. Median follow-up was 18.0 months (IQR, 6.5-30.1 months). Successful use of fistula for dialysis, fistula patency and survival were assessed. RESULTS: 441 primary fistulas were formed in the study period. Median age was 67.5 years (IQR, 54.0-75.2 years). 71% of all fistulas were formed at the wrist. Trainees performed 31.1% of all operations. The two groups (trainees and consultants) were well matched for age, sex, diabetes, and fistula type. Only 70.5% of patients proceeded to long-term haemodialysis. There were no significant differences in the successful use of AVF for dialysis or patency rates between the two groups. One and two year fistula survival in this group was 87.7% and 78.3% for trainees and 80.8% and 71.1% for consultants (P = 0.288 log rank). CONCLUSIONS: Surgical trainees can perform primary AVF surgery without significantly reducing fistula outcomes. Vascular access surgery can be utilised as a training operation.

Aged↗
PubMed2002

Is day case surgery the key to basic surgical training?

The logbooks of 5 senior house officers (SHOs) were audited to determine progression of surgical skills on a single vascular firm. Total surgical experience and, in particular, experience in varicose vein and arterio-venous fistula surgery, performed in the day-case unit (DCU), were examined. Trainees were divided into those undertaking their first surgical SHO post (group 1, n = 2) and those who had had previous surgical exposure (group 2, n = 3) on the basic surgical training rotation. SHOs were exposed to a mean of 273 (+/- 41 SD) operative cases in 6 months. Emergency work comprised 15% (+/- 7%) of workload. Day cases accounted for 35% (+/- 3%) of elective workload. A mean of 66 (+/- 5) varicose vein and AVF cases were undertaken in the DCU. This represented 82% (+/- 6%) of day-case operative experience for the firm. SHOs undertook 12 (+/- 6) VV/AVF cases unassisted, 35 (+/- 5) cases with senior assistance, and 20 (+/- 11) as first assistance in the DCU. All SHOs progressed to being able to perform arterial bypass and amputation (with senior assistance) during their time on the firm. There was no significant difference in experience or progression to major vascular surgery between group 1 and group 2 in this study except in lower limb amputation procedures. It is concluded that vascular surgical firms can provide a good introduction to surgical skills. Most experience as first operator was gained in the DCU and we suggest that those undergoing basic surgical training might benefit from an attachment to the DCU early in their rotations.

Ambulatory Surgical Procedures↗
PubMed1999

Comparison of microemulsion and conventional formulations of cyclosporine A in preventing acute rejection in de novo kidney transplant patients. The U.K. Neoral Renal Study Group.

BACKGROUND: The microemulsion preconcentrate formulation of cyclosporine A (CsA) (Neoral) exhibits more uniform pharmacokinetics than the conventional formulation (Sandimmun; SIM). This randomized, open-label, U.K. multicenter study compared the efficacy, safety, and tolerability of Neoral and SIM in preventing acute rejection in de novo renal transplant recipients. METHODS: Adult cadaveric kidney recipients (n=293) received Neoral or SIM twice daily for 12 months. Initially identical Neoral and SIM doses were titrated, maintaining trough CsA levels within locally defined therapeutic limits. RESULTS: In the year after transplantation, acute rejection occurred in 34% of the Neoral and 47% of the SIM recipients (P=0.037). In the intent-to-treat population, fewer treatment failures (defined as acute rejection, graft loss, withdrawal, or death) occurred in the Neoral (45%) than the SIM recipients (58%) (P=0.015) and therapeutic CsA levels (> or =250 microg/L) were reached faster with Neoral than SIM (P=0.0017). Antibody treatment of refractory rejection was used slightly less in the Neoral group (Neoral: 10%; SIM: 12%). One-year patient and graft survival rates (excluding deaths with functioning grafts) were 95% and 88%, respectively, for Neoral and 96% and 89% for SIM. Both formulations were well tolerated. No differences were observed between therapies in the nature, frequency, or severity of adverse events. Neoral use was not associated with increased nephrotoxicity or excessive immunosuppression. CONCLUSIONS: Neoral reduced the incidence of acute rejection compared with SIM, without significant increases in adverse events. This was achieved without altering existing SIM protocols and was attributed to improved absorption of CsA from Neoral and less variability in whole blood CsA concentrations.

Acute Disease↗
PubMed1999

The morbidity of secondary vascular access. A lifetime of intervention.

OBJECTIVES: to examine the outcome and incidence of access-related procedures in patients who dialyse via PTFE secondary access grafts. DESIGN: retrospective case note study. RESULTS: recipients of secondary access procedures face a lifetime of haemodialysis access interventions. In total, 639 access-related procedures were performed on the 72 patients studied. At the end of the study five patients were wholly reliant on central venous catheters for dialysis access. Patients with secondary access grafts have little hope of transplantation; only six of 72 patients received a transplant after a secondary access procedure. CONCLUSION: the increasing number of patients coming to synthetic access-graft procedures and the morbidity of such procedures mean that surgeons should adopt strategies to minimise the use of grafts and limit the number of interventions performed. Careful planning will also reduce the number of central line placements and help to reduce the morbidity associated with long-term haemodialysis. Increasing resources will be required to meet the rising demand for secondary access provision.

Adult↗
PubMed1999

The spouse as a kidney donor: ethically sound?

A shortage of cadaver donor organs requires transplant units to examine all possible alternatives. Transplantation from living donors accounts for only approximately 10% of kidney transplants in the UK. Recent studies have shown that the results of kidney transplantation between spouses are at least as good as those of well-matched cadaver organs, but very few transplants of this type have been performed in this country so far. As part of the assessment process, the proposed donor and recipient are required to provide written statements about the issues. We reproduce here the personal statements made by one of our patients and his wife: we believe that the statements support our contention that spousal transplantation is ethically justifiable and should be more widely available. We report our early experience in Bristol with seven kidney transplants from spousal donors and we encourage other renal units in this country and elsewhere to consider this method of improving the prospects of kidney transplantation for their patients.

Adult↗
PubMed1998

[Distal femoro-popliteal bypass using Esmarch tourniquet ischemia].

The Esmarch bandage is an effective substitute for vascular clamps in distal femoro-popliteal or tibial bypass surgery. Intimal trauma caused by clamping is avoided, vasa vasorum are preserved due to only semicircumferential dissection of vessels. This method is particularly suitable for heavy calcified rigid vessel walls. We demonstrate this technique, which was employed in 8 patients (10 bypasses). The use of this technique requires neither a longer operation- nor clamping time. The postoperative course of all but one patients develops normally and the technique does not provoke any pathological results in the area of operation. Advantages of the procedure compared to conventional techniques will be discussed.

Aged↗
PubMed1994

Effect of small bowel transplantation, denervation and ischaemia on rat intestinal microflora.

The effects of denervation and warm ischaemia on quantitative and qualitative changes in small intestinal microflora following rat heterotopic small-bowel isotransplantation were assessed. Animals with Thiry-Vella fistula, but without transplants, acted as controls. Thirty and 40-fold increases in bacterial colony counts were seen in the isografts compared to controls at 2 and 7 days, respectively (P < 0.05). Aerobic faecal organisms predominated at 2 and 7 days, but an overgrowth of Flavobacterium meningosepticum occurred at 28 days in the transplanted and host bowels. The effect of warm ischaemia on intestinal microflora was assessed by the application of a microvascular clamp to the superior mesenteric artery for 90 min. The effect of denervation was assessed following microsurgical division of all nervous tissue around the superior mesenteric artery. After 7 days, lengths of jejunum and ileum were removed and intraluminal microflora assessed. The number of bacterial colonies isolated from the ileum in the warm ischaemia group was six times greater than the number in the control group, whereas no significant changes were seen in the upper bowel. In contrast, denervation led to a slight, but consistent, decrease in colony counts. These findings suggest that the increase in bacterial numbers in an isografted small bowel primarily results from warm ischaemia rather than from mesenteric denervation, and that physical aspects of the procedure may affect the development of sepsis following small-bowel transplantation.

Animals↗
PubMed1993

Method for diagnosing rejection in small bowel transplantation.

Diagnosis of rejection in small bowel transplantation by the identification of a host-cell infiltrate is hampered by the physiological trafficking of host lymphocytes to the 'gut-associated lymphoid tissue' of the graft. This study compared physiological host-cell infiltration of small bowel grafts with that occurring in rejection and stable immunosuppression. Physiological host-cell infiltration, where the graft does not present an immune stimulus to the host, was assessed by transplanting bowel from DA to (DA x PVG) F1 hybrid rats. The extent of host-cell infiltration was determined by immunohistochemical analysis. In the lamina propria, considerable infiltration by host cells was seen, although it was significantly less than that in rejection or stable immunosuppression. By contrast, host cells were seen in the intraepithelial compartment only in rejection. Host-cell infiltration in the absence of an allogeneic stimulus suggests that histological identification of host cells in the lamina propria is not necessarily indicative of rejection. However, the presence of host cells in the intraepithelial compartment is specific for rejection in small bowel transplantation.

Animals↗
PubMed1993

The effect of rejection and graft-versus-host disease on small intestinal microflora and bacterial translocation after rat small bowel transplantation.

Bacterial translocation and the development of sepsis after small bowel transplantation may be promoted by immunological damage to the intestinal mucosa or by quantitative and qualitative changes in intestinal microflora. This study assessed the effects of rejection, graft-versus-host disease (GVHD) and immunosuppression on intestinal microflora and bacterial translocation after heterotopic rat small bowel transplantation. Isografts, allografts with and without CsA immunosuppression, and the semi-allogeneic parent to the F1 hybrid GVHD model were studied. Intestinal microflora in graft and host loops and bacterial translocation to host organs and the graft mesenteric lymph node were determined. Bacterial colonies were counted and individual colonies identified using API 20E nutrient and fermentation indicator techniques. Colony counts in isografts and allografts were significantly higher than in the native intestine, whereas there was a massive overgrowth in the native intestine in the GVHD group. The species profile for the host and graft loops was similar in animals that had received isografts, allografted animals receiving CsA, and animals undergoing GVHD. However, there was a large increase in Staphylococcus epidermidis in animals with rejection. Bacterial translocation was not detected in isografted animals, but was observed in all other animal groups, with S. epidermidis being the most prevalent organism. These findings demonstrate that rejection and GVHD are associated with shifts in intestinal microflora toward potentially pathogenic organisms and that bacterial translocation into recipient tissues poses a major threat for the development of sepsis.

Animals↗
PubMed1992

Persistence of allogeneic cells in graft and host tissues after small bowel transplantation.

Small bowel transplantation is associated with a significant risk of graft versus host disease owing to the large amount of organized lymphoid tissue within the graft. This study assessed whether graft lymphoid cells could persist in the long term following fully allogeneic small bowel transplantation when graft rejection was prevented by cyclosporin immunosuppression. Transplantation was carried out between PVG and DA strains of rat. Cyclosporin (15 mg/kg) was given daily from transplantation, and groups of animals were studied at 28 and 56 days after grafting. The proportions of donor- and recipient-derived cells in the graft and in the host gut and lymphoid tissues were assessed using immunohistochemical tissue staining and monoclonal antibodies specific for cells expressing class I antigens from the two strains of rat. Results demonstrated a persisting population of graft-derived T cells which were capable of migration to the host. Therefore, there may be a long-term risk of graft versus host disease after small bowel transplantation under cyclosporin immunosuppression.

Animals↗
PubMed1992

Potential candidates for small bowel transplantation.

The number of potential candidates for small bowel transplantation in the UK is unknown. Potential recipients are those with irreversible small intestinal failure, including those treated with permanent parenteral nutrition. This study of one of the largest groups of patients receiving such nutrition identified ten of 25 adult patients as possible recipients. The remaining 15 were considered unsuitable, mainly because of multiple previous abdominal operations or abscesses. Extrapolation of these data to national figures on the incidence of irreversible small intestinal failure suggests that each year up to 20 new adult patients in the UK might benefit from small bowel transplantation.

Adolescent↗
PubMed1992

Reduction of graft-versus-host reactivity after small bowel transplantation: ex vivo treatment of intestinal allografts with an anti-T cell immunotoxin.

A specific T lymphocyte immunotoxin was used to pre-treat small bowel grafts in an attempt to prevent graft-versus-host (GVH) reactivity and GVH disease in a rat transplant model. The immunotoxin used was a conjugate of the anti-CD5 MoAb MRC OX-19 with ricin A chain. The grafts were perfused ex vivo with a standard solution of immunotoxin followed by incubation at 4 degrees C for 1 h before transplantation. In a semi-allogeneic strain combination (parent to F1 hybrid offspring) graft treatment with immunotoxin led to a prolongation of recipient survival compared with groups receiving similar transplants without immunotoxin treatment. An additive effect on survival was observed when the host was treated with cyclosporin. The effect of immunotoxin was greater than that of mesenteric lymphadenectomy in increasing host survival. The effect of graft treatment with the immunotoxin on cellular migration from graft to host lymphoid tissues was assessed in fully allogeneic transplantation (PVG to DA). Host lymphoid tissues were subjected to immunohistochemical analysis using a MoAb specific for donor class I MHC antigens. Graft treatment with the immunotoxin led to a significant decrease in the number of graft cells found in host lymphoid tissues 7 days after transplantation. However, this effect was less marked than that achieved by graft mesenteric lymphadenectomy. With our current protocol graft treatment with a specific T cell immunotoxin can significantly reduce but not abolish GVH reactivity in rat small bowel transplantation.

Animals↗