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Biomedical subjects

L H Buhler

Publications and source records attributed to L H Buhler.

7 recordsLinked to original sources
PubMed2006

An audit of surgical management of gastrointestinal stromal tumours (GIST).

AIM: To analyze GIST outcome after primary resection and to determine if a new grading system could adequately predict there prognosis. METHODS: A retrospective review (1993-2002) identified 80 patients who underwent primary surgical resection for, c-KIT positive, GIST. Follow-up was complete for all patients (median follow-up 42, range 1-132, months). GIST were classified as low or high grade according to the following parameters: size, mitotic rate, mitotic index (MiB1), presence of necrosis, invasion of adjacent structure and presence of metastasis. RESULTS: GIST originated from the stomach (46), small bowel (30), colon and rectum two and mesentery two. At surgery, 94% of cases presented with localized disease and 6% blood born metastasis with or without lymph node invasion. Resections were complete (R0) in 72 cases. R0 resection correlated with prognosis (p<0.01). Sixty GIST were classified as low grade (median follow-up 60 months) and 20 as high grade (median follow-up 27 months). Five-year actuarial survival of patients with low or high grade GIST were of 95 and 21%, respectively, (p<0.001). CONCLUSION: Prognosis of GIST after surgical treatment is influenced by completeness of primary resection and tumour malignant potential. Low grade GIST have an excellent prognosis after surgery alone, while high grade GIST have a high rate of recurrence after primary resection. Adjuvant treatment should be advocated for patient with either high grade GIST or after incomplete primary resection. The presented grading system can reliably predict GIST outcome after primary surgical treatment. Complete surgical resection offers good chance of cure for low grade GIST, while for high grade GIST surgery alone is not sufficient. The presented grading system could be used to identify patients who may benefit of adjuvant treatment with imatinib mesylate after GIST resection.

Adult↗
PubMed2006

Pig-to-nonhuman primate islet xenotransplantation: a review of current problems.

Islet allotransplantation has been shown to have potential as a treatment for type 1 diabetic patients. Xenotransplantation, using the pig as a donor, offers the possibility of an unlimited number of islets. This comprehensive review focuses on experience obtained in pig-to-nonhuman primate models, particularly with regard to the different types of islets (fetal, neonatal, adult) and isolation procedures used, and the methods to determine islet viability. The advantages and disadvantages of the methods to induce diabetes (pancreatectomy, streptozotocin) are discussed. Experience in pig-to-nonhuman primate islet transplantation studies is reviewed, including discussion of the possible mechanisms of rejection and the immunosuppressive regimens used. The research carried out to date has led to workable animal models to study islet xenotransplantation, but several questions regarding methodology remain unanswered, and details of these practicalities require to be adequately addressed. The encouraging porcine islet survival reported recently provides an indicator for future immunosuppressive regimens.

Aging↗
PubMed2004

Immunosuppression for pancreatic islet transplantation.

Protocols for islet transplantation have to take into account the diabetogenicity/islet toxicity of the immunosuppressive agents, namely corticosteroids and calcineurin inhibitors, most notably tacrolimus. The development by the Edmonton group of a sirolimus-based, steroid-free, low-tacrolimus regimen was a significant breakthrough that allowed the rate of insulin independence after islet transplantation to increase from 13% to 80% at 1 year. Drawbacks include the side effects of sirolimus and the reduction in insulin independence to 50% at 3 years, the latter being attributed to prolonged tacrolimus exposure. Currently explored alternatives to tacrolimus include cyclosporine, mycophenolate mofetil, and the novel agent FTY 720. Perspectives for the near future involve the achievement of "prope tolerance" by strategies using lymphocyte-depleting antibodies (anti-thymocyte globulin, campath-1H, hOKT3gamma1 [ala,ala]), or costimulatory blockade (anti-CD154 mAbs, CTLA4-Ig).

Cyclosporine↗
PubMed2004

Five-year follow-up after pediatric living related small bowel transplantation between two monozygotic twins.

Two 13-year-old monozygotic twins were used for living related small bowel transplantation (SBTx). The recipient presented with short gut syndrome secondary to complicated abdominal surgery. The indication for SBTx was based on a failure to thrive and a poor tolerance of TPN. The donor was an identical twin, as demonstrated by skin graft acceptance, which allowed performance of SBTx without immunosuppression. Growth charts were used to follow intestinal absorption functions and body composition. The donor was used as a control for the recipient. The recipient, who was transplanted with 160 cm of donor ileum, was discharged on postoperative day 62 on a regular diet. Before SBTx the recipient was 10 kg lighter in body weight than the donor, a gap that was progressively reduced over the follow-up period. A height deficit of 3 cm reversed within 1 year after SBTx. A 10-kg deficit in fat-free body mass was completely extinguished within 18 months. By 18 months posttransplant, recipient serum albumin and prealbumin were normal and comparable to donor values. d-Xylose absorption in the recipient remained lower than that in the donor. Within 6 months fecal fat excretion normalized in the recipient. d-Xylose absorption and fecal fat excretion were always within a normal range in the donor.

Adolescent↗
PubMedDate not supplied

[Diabetes Type I therapy through transplantation].

Diabetes is one of the most common chronic diseases in our society. While insulin treatment for diabetes type I could delay and reduce the incidence of diabetic complications, it is associated with an increased risk of severe hypoglycemia. To restore physiologic insulin metabolism, transplantation of insulin producing cells (pancreatic Beta cells) represent the sole available therapy. It could be done either through pancreas or islet of Langerhans transplantation. In this paper, we review actual knowledge regarding these two types of transplantations.

Diabetes Mellitus, Type 1↗
PubMedDate not supplied

Treatment of fulminant liver failure by transplantation of microencapsulated primary or immortalized xenogeneic hepatocytes.

BACKGROUND: The aim of this study was to evaluate the in vitro and in vivo function of hepatocytes after immortalization, cryopreservation, encapsulation, and xenotransplantation into mice with fulminant liver failure (FLF). METHODS: Rat and human hepatocytes were isolated by collagenase digestion. Human hepatocytes were immortalized using lentiviral vectors. Rat and immortalized human hepatocytes (IHH) were encapsulated in 400 microm of alginate-poly-L-lysine (PLL; Sigma, Buchs, Switzerland)-alginate membranes and cryopreserved using a computerized device. In vitro, encapsulated hepatocytes (cryopreserved or noncryopreserved) were cultured; albumin secretion was measured by enzyme-linked immunosorbent assay. Microencapsulated (cryopreserved or noncryopreserved) hepatocytes were transplanted intraperitoneally to mice with FLF: group 1 (n = 10) transplantation of empty capsules; group 2 (n = 12) transplantation of free primary rat hepatocytes; group 3 (n = 12) transplantation of cryopreserved encapsulated rat hepatocytes; group 4 (n = 10) transplantation of encapsulated rat hepatocytes; group 5 (n = 9) transplantation of cryopreserved encapsulated IHH; group 6 (n = 10) transplantation of encapsulated IHH. RESULTS: Compared with free primary hepatocytes, cryopreserved or noncryopreserved encapsulated rodent hepatocytes showed similar levels of continuous in vitro albumin secretion over 1 week. Cryopreserved or noncryopreserved encapsulated IHH showed minimal albumin secretion compared with free primary human hepatocytes. Fulminant liver failure, produced by a combination of acetaminophen and 30% hepatectomy, resulted in a 20% to 30% host survival. In groups 1 and 2, survival was unmodified, compared with untreated mice. For groups 3 and 4, transplantation of cryopreserved or noncryopreserved encapsulated rat hepatocytes significantly increased survival rates to 66% and 80%, respectively (P < .01). For groups 5 and 6, transplantation of cryopreserved or noncryopreserved encapsulated IHH improved host survival to 50% and 55%, respectively (P < .05). CONCLUSIONS: Primary rodent hepatocytes maintained synthetic functions after encapsulation and cryopreservation. Immortalized human hepatocytes showed minimal albumin secretion in the absence of encapsulation and cryopreservation, suggesting that hepatocytes lose some specific functions after immortalization. After induction of FLF in mice, intraperitoneal transplantation of encapsulated (primary or immortalized, cryopreserved or noncryopreserved) xenogeneic hepatocytes significantly improved survival. These results indicate that naive and genetically modified hepatocytes can be successfully encapsulated, stored by cryopreservation, and transplanted into xenogeneic recipients with FLF to sustain liver metabolic functions.

Animals↗