Improved insulin secretion of cryopreserved human islets by antioxidant treatment

The viability of islets of Langerhans prior to grafting is believed to influence the clinical outcome of islet transplantation. To determine whether oxidative stress occurs during the isolation-purification procedure as well as during tissue culture and cryopreservation, we have measured the glutathione redox state (GSH/GSSG) of islets. Human islets were purified by standard techniques from organ donors, cultured, and cryopreserved. Glucose-induced insulin release was monitored in parallel during static incubations to assess the function of the islets. Cultured human islets responded by a 2.2-fold increase in insulin release to a glucose challenge. After cryopreservation the hormonal response was lower. Immediately after islet isolation the GSH/GSSG ratio was 25.2 +/- 5.2, and it increased slightly to 32.0 +/- 6.1 after 1-3 days in tissue culture. The GSH/GSSG decreased significantly after cryopreservation to 12.2 +/- 3.4, suggesting that the freezing and thawing procedures imposed oxidative stress on the islets. To explore this hypothesis further, cryopreserved islets were treated with the antioxidant butylated hydroxyanisole (BHA). Islets exposed to BHA showed an improved glucose-induced insulin release and had an increased insulin content. BHA also protected the islets when they were exposed to alloxan, a free radical generating agent. However, after cryopreservation, BHA treatment did not modify the glutathione redox state. Although the BHA effect could not be explained merely by a change in the glutathione redox state, it is not precluded that redox changes of other cell components ameliorate the glucose sensitivity of the beta cells. Further studies will be needed to determine possible ways of improving islet cryopreservation with antioxidant treatments and particularly, to validate the present observations by in vivo experiments in the context of clinical islet transplantation.

[Autotransfusion of shed mediastinal blood after open heart operation]

This prospective study was designed to determine whether the autotransfusion of shed mediastinal blood (ATS) after open heart surgery is safe and effective. Forty-two patients undergoing cardiac operation were randomized to receive either nonwashed shed mediastinal blood (group 1; n = 22) or banked blood (group 2: n = 20). No difference in mean age (group 1: 49 +/- 11 years; group 2: 45 +/- 12 years), coronary artery bypass grafting (group 1: n = 5, 23%; group 2: n = 6, 30%), valve replacement (group 1: n = 17, 77%, group 2: n = 14, 70%), and mean preoperative hemoglobin level (group 1: 13.7 +/- 2.3, group 2: 14.4 +/- 1.6) was noted between non-ATS and ATS groups (p = not significant). The mean hemoglobin levels after operation were similar in the two groups (group 1: 11.89 +/- 1.52; group 2: 12.03 +/- 1.34). No difference in the mean blood loss 4, 6 and 24 hours after operation (group 1: 33 +/- 190, 420 +/- 340 and 550 +/- 300; group 2: 340 +/- 230, 420 +/- 280 and 670 +/- 380) was observed between the two groups. The mean volume autotransfused in group I was 380 +/- 230 ml (200 approximately 1300 ml). In group I, the patients required bank blood 1080 +/- 720, compared with 1780 +/- 1045 in group II. The bank blood requirement in group I reducted by 40%. These data demonstrate that ATS after open heart surgery is safe and effective.

[A preliminary study of the preventive and blocking effect of green tea grown in mengding mountain area on the esophageal cancer in rats]

Three groups (positive control or nitrosamine alone group, test group and control group) were included in this experiment. After the begining of the experiment, the rats of test group were given 2% green tea (common grade) solution by free drinking daily for 24 weeks. After 2 weeks of the begining of the experiment, the rats of the nitrosamine alone group and test group were injected with MANA, 5 mg/kg weekly for 20 weeks. The animals were sacrificed at 4 intervals. The incidence rates of esophageal cancer in the rats of the two groups sacrified at every interval were significantly different. The result suggested that green tea should have a preventive and blocking effect on the occurrence of esophageal cancer in rats.

New synthetic sulfated oligosaccharides prolong survival of cardiac xenografts by inhibiting release of heparan sulfate from endothelial cells

Binding of recipient natural antibodies to the endothelium of the graft, complement activation, endothelial cell activation, and microvascular thrombosis are major events in the hyperacute rejection of organ xenografts. The aim of this study was to investigate the effects of two new synthetic sulfated oligosaccharides (A and B) on the survival of discordant cardiac xenografts in the guinea pig-to-rat model. In untreated recipients, hyperacute rejection occurred in 5 min (median; range, 4-6 min) and immunohistological analysis of all the grafts revealed deposition of IgM and C3 along the endothelium. Administration of oligosaccharides A and B prior to revascularization prolonged the survival of xenografts in a dose-dependent manner, up to 113 min (median; range, 42-145 min) and 86 min (median; range, 35-108 min), respectively, when doses of 20 mg/kg were used. There were no bleeding complications. Histological examination of the rejected grafts showed a picture of hyperacute rejection, with no difference in IgM and C3 deposition as compared with the untreated animals. In cell culture experiments, the release of heparan sulfate from guinea pig cardiac endothelial cells induced by rat serum was inhibited by both saccharides in a dose-dependent manner. The results indicate that these new synthetic sulfated oligosaccharides are effective for prolongation of discordant xenograft survival, possibly by interfering with endothelial cell activation. Such substances may be of value in other xenotransplant combinations.

Combined islet-lung transplantation in a cystic fibrosis patient

The prevalence of insulin-dependent diabetes mellitus (IDDM) in cystic fibrosis patients ranges from 2 to 8% and glucose intolerance up to 15%. In recent years, lung transplantation has helped to prolong life expectancy of cystic fibrosis patients and represents 10 to 30% of all indications for lung transplantation. The postoperative need for immunosuppressive therapy using diabetogenic agents has decompensatory effects on glucose regulation and will probably increase the number of insulin-dependent cystic fibrosis patients. We report the case of an insulin-dependent cystic fibrosis patient transplanted with a combined islet-lung allograft. The pre-transplantation C-peptide level was below 0.04 nmol/l and preoperative insulin requirement was some 100 U per day. A sequential bipulmonary lung transplantation was performed and, using the pancreas of the same donor, we isolated and purified the islets of Langerhans by a modified automated method. We obtained 232,200 islets equivalent, which were injected into the liver by portal embolization. The postoperative course was uncomplicated, the insulin requirement decreased to 50% of the preoperative need and the C-peptide value increased to normal values and remained with the normal range during a follow-up period of 15 months. In conclusion, we believe that, besides type I diabetic patients, insulin-dependent cystic fibrosis patients with a negative C-peptide value could also be good candidates for combined islet-lung allotransplantation.

[Isolation and cryopreservation of human islets of Langerhans]

Islet transplantation represents an alternative to whole pancreas transplantation for the treatment of patients suffering from diabetes type I. The transplantation of a sufficient number of islets is an essential condition for successful allograft. Islet cryopreservation allows the storage of islet preparations for subsequent pooling, at the time of transplantation, of cryopreserved islets with a fresh preparation in order to increase the mass of transplanted pancreatic endocrine tissue. From May 1994 to April 1995, islets were isolated from 22 human pancreases using a modified automated method, and 19 preparations were cryopreserved. The function of cryopreserved islets was tested in vitro (static incubation and perifusion). The results of static incubation experiments confirmed that the insulin secretion of cryopreserved human islets in response to glucose stimulation was comparable to the response of islets that have not been frozen. In static incubation experiments, the mean (+/- SEM) insulin secretion of islets, prior to cryopreservation, was 239.3 (+/- 58.9) and 479.5 (+/- 59.5) pg/islet/15 min at 2.8 mM glucose and 16.7 mM glucose respectively. The mean (+/- SEM) insulin secretion of cryopreserved islets was 274 (+/- 103.2) and 468.5 (+/- 191.9) pg/islet/15 min at 2.8 mM and 16.7 mM glucose respectively. The perifusion experiments also demonstrated a significant increase of insulin secretion from cryopreserved islets perifused with a stimulating glucose concentration. Our experiments allow us to envisage the use of cryopreserved islet preparations for allotransplantation in diabetic patients.

[A preliminary observation of preventive and blocking effect of Gynostemma pentaphyllum (Thunb) Makino on esophageal cancer in rats]

Gynostemma pentaphyllum (Thunb) Makino is a kind of natural plant growing in the southern provinces of China. In this experiment, rats were given drinks of 2% Gynostemma Pentaphyllum (Thunb) makino aqua boiled solution freely for 2 weeks before administration of carcinogen. Subsequently, the rats were injected with carcinogen (MANA) for 18 weeks and were sacrificed at intervals. The result showed that the number of cases of esophageal epithelial papilloma, the average number of tumor and the incidence of esophageal cancer in the experimental group were lower than those in the control group (MANA only), though no statistical significant difference was found. The initiation of cancer was delayed for 6 weeks. These indicated that Gynostemma Pentaphllum Makino might have some preventive and blocking effect on esophageal cancer in rats.

[Changes in serum granulocyte colony-stimulating factor (G-CSF) in burned patients]

Serum G-CSF level was assayed in 20 burned patients (TBSA > or = 30%) 2 weeks postburn. In 11 of them plasma endotoxin was also measured. The results showed serum G-CSF level was increased in 87.5% (7/8) of burned patients with exceeding 50% TBSA and in 58.3% (7/12) of patients with 30%-50% TBSA, and in the former it was earlier increased (1-5 day postburn) than the latter (5-11 day postburn). Serum G-CSF was increased in 90% of the burned patients with wound sepsis. Increased of serum G-CSF in burned patients, especially in those exceeding 50% TBSA, indicates the occurrence of sepsis.

[Islets of Langerhans allografts in the pig: initial results]

Islet of Langerhans transplantation represents a promising treatment of diabetes. Use of porcine islets for xenotransplantation could offer a solution to shortage of organ donors. However, isolation of pig islets remains a real challenge because of their marked fragility. Using a modified automated method for islet isolation, we performed 10 intraportal islet allografts in pigs. Surgically pancreatectomized pigs were transplanted with purified islet preparations pooled from pancreases of 3 donors (slaughter-house pigs, age 5-8 months). Six recipients were not immunosuppressed and four received an immunosuppressive treatment of Cyclosporine and Azathioprine. In the first group (non-immunosuppressed recipients), insulin secretion was observed for a mean of 4.8 days after transplantation. In the second group (with immunosuppressive treatment) the recipients sustained an insulin secretion for 6-9 days. However, in both groups liver biopsies showed signs of acute rejection and destruction of the transplanted islets. Pig islet allotransplantation, using as recipients surgically pancreatectomized pigs, can be considered as a suitable model to assess the functional results of mass islet isolation. We were able to reverse diabetes transitory in a large animal, by transplantation of purified pig islet preparations. However, even when an immunosuppressive treatment was administered to the recipients, rejection seemed to represent an important factor in the functional outcome of the islet grafts.

[Mechanism of rejection of islet of Langerhans xenografts]

For immediately vascularised xenografts, the presence of preformed antibodies associated with the activation of the complement induces a hyperacute humoral rejection in discordant combinations. For neovascularised xenografts, such as the islets of Langerhans, the absence of an initial vascularisation prevents the acute humoral rejection and there is some evidence to suggest that the rejection is cell mediated. To analyse the influence of species response to cellular transplantation, we compared the functional outcome and the immunohistochemical analysis of concordant and discordant xenotransplated islets with allotransplanted islets of Langerhans. In the concordant xenotransplantation experiment, rat (Sprague Dawley) purified islets (N = 600) were transplanted under the kidney capsule of streptozotocin diabetic mice. In the discordant experiment, purified human islets (N = 1000), in the allotransplantation model Balb mouse islets (N = 600) were transplanted under the kidney capsule of C57BL/6 mice. Daily blood glucose levels were monitored until rejection occurred (blood glucose > 11 mMol/L) and kidney biopsies were taken every second day for immunohistological examination. In allotransplanted mice, rejection occurred after a mean of 15 +/- 4 days, in concordant xenotransplanted mice after a mean of 10 +/- 3 days and in the discordant xenotransplanted mice after a mean of 8 +/- 1 days. The immunohistological analysis showed in both xenotransplantation models a deposit of IgM and C3 surrounding the grafted cells, starting at day 1 and persisting until rejection, associated with the presence of Mac-1 positive cells. The intensity of the humoral response was moderate to important in the concordant group, but very strong and unchanged until rejection in the disconcordant group. An invasion with CD4+ and CD8+ cells started between day 4 and 6 in both groups, progressively increasing until rejection. In the allotransplantation model, no humoral response was detectable and the cellular response started between day 10 and 12 after transplantation. We conclude, that a cellular response is involved in the rejection process of both concordant and discordant xenotransplanted islets of Langerhans. Compared to an allotransplantation model, the humoral response does not destroy the function of transplanted islets, but could trigger or accelerate the cell-mediated response.

[Application of gasless laparoscopic device in laparoscopic surgery]

The aim of this study was to evaluate the gasless laparoscopic device (GLD) in laparoscopic surgery. GLD, independently designed and manufactured by ourselves in 1993, incorporates a manipulator and laparoscopic abdominal retractor. From August to October 1993, we conducted an experimental study on gasless laparoscopic cholecysto-duodenostomy in 5 dogs. Four of them were completely successful and one was converted to open surgery due to gallbladder rupture. The result showed that GLD could maintain good exposure in laparoscopic surgery, laparoscopic suturing and knotting could become easier and operative cost could be reduced with conventional instruments. We also developed an intracorporeal "Chinese Knotting" and a self-designed push tube for extracorporeal knot tying. During April and August 1994, we successfully applied our modified GLD in gasless laparoscopic cholecystectomy, inguinal herniorrhaphy laparoscopic-assisted sigmoidectomy, abdomino-perineal resection of rectal carcinoma.

[The effects of mupirocin on burned wound with Staphylococcus aureus infection]

The therapeutic results of 41 cases of S. aureus infected burn wound (average 2.1% TBSA, approximately 200 cm2) treated with Mupirocin are reported in this paper. The effects of Mupirocin was obviously superior to that of SD-Ag used in control group. During the observation period the total effective rate of the studied group was 88.9% (control group: 70%, P < 0.05) and the bacterial clearance rate of S. aureus from the wound was 88.8% (control group: 40% P < 0.05). The sensitivity of 30 strains of S. aureus isolated from burn wounds to 11 varieties of antibiotics indicated that the sensitive rate to Mupirocin was as high as 92.68%, only lower that Vanconmycin. The bacteriological assay (MIC < or = 0.25 mg/L, MIC < or = 4 mg/L) also showed high sensitivity of S. aureus to Mupirocin. We suggest Mupirocin be the first choice of topical antibacterial agents for burn wound with S. aureus infection, especially for infection with MRSA.

[Heterogeneity of the immunoreactivity of A14, A19, B16 and B26- (125I) monoiodoinsulin to different species of anti-insulin immuno sera]

By using lactoperoxidase oxidation with 6 mol. urea in the reaction medium, the four tyrosine residues contained in insulin molecule were iodinated as monoiodoinsulins. These tracers, namely A14, A19, B16 and B26- (125I) monoiodoinsulins were separated with polyacrylamide gel electrophoresis+QAE-Sephadex A25 chromatography. The present study demonstrated that the radiochemical purity of these tracers was high (> 98%) and the specific radioactivity also high. The binding of these tracers to surplus insulin antibody was more than 95%. These our tracers were tested in two RIA systems against 35 species of guinea-pig anti-insulin immuno sera to compare their immunoreactivity (Ka, Scatchard analysis) to each immunoserum. The two RIA systems were antibody dilution and self displacement, and in both of them, only iodinated insulin and insulin antibody were present in the reaction fluid. The results showed that for 16 antiinsulin immuno sera, Ka for A14, A19, B16 or B26-monoiodoinsulin were significantly different, and for the rest 19 immuno sera no significant difference could be detected. The possible mechanism and implication of this phenomenon were discussed.