Preservation of canine segmental pancreatic autografts: cold storage versus pulsatile machine perfusion

The reliability of cold storage and pulsatile machine perfusion for preservation of open-duct segmental pancreatic grafts for 24, 48, and 72 hours was determined in a canine autograft model. The tail (left limb) of the pancreas on a pedicle of splenic artery and vein was transplanted to the pelvis with vascular anastomoses to the iliac vessels and the remainder of the pancreas was excised. Twenty nonpreserved grafts functioned immediately (the recipients became normoglycemic, plasma glucose less than 150 mg/dl), 16 long term (80%). Collins solution (CS, osmolality 300 mosm/kg) and a silica gel filtered plasma solution (SGF-I, osmolality 430 mosm/kg) were compared for cold storage at 4 degrees C. The long-term functional survival rate for grafts stored for 24 hours in SGF-I was 9/12 (75%) and in CS was 8/12 (67%). When graft preservation time was extended to 48 hours, 9/12 (75%) stored in SGF-I and 4/10 (40%) in CS functional long term. The preservation failure rates were 0% in grafts stored in SGF for up to 48 hours, but were 20% and 50% for grafts stored in CS for 24 and 48 hours. Storage at 72 hours was not satisfactory; even when SGF-I was used, the preservation failure rate was 57%. SGF was also used as the perfusate for pancreas preservation on the Mox-100 machine at a pressure of 30 mm Hg (achieved by leaving the port opposite the connected pancreas open). Lower pressures gave insufficient perfusion and higher pressures led to severe edema of grafts. Mean (+/- S.E.) flow (ml/min) through the grafts were 4.5 +/- 0.3 initially, 6.5 +/- 0.7 at 24 hours and 6.3 +/- 0.9 at 48 hours. With SGF-I only 6/12 (50%) of grafts perfused for 24 hours and only 1/8 (12%) for 48 hours functioned long term. With a modified perfusate (SGF-II, osmolality 470-500 mosm/kg) the results were slightly improved; 7/12 (58%) grafts perfused for 24 hours and 5/10 (50%) for 48 hours functioned long term. The mean (+/- S.E.) flow rate (ml/min) was 5.0 +/- 0.6 in grafts that functioned long term and was 8.3 +/- 1.0 in those that failed due to preservation complications. Mean (+/- S.E.) peak serum amylase levels (I.U./L.) were similar in recipients of fresh grafts (3953 +/- 365) and those stored hypothermically in SGF (4226 +/- 327), but were significantly lower in recipients of machine perfused grafts (2988 +/- 228). Although the percentage of successful transplants varied according to the preservation techniques, the mean (+/- S.E.) IVGTT K-values in recipients with functioning grafts were similar between the groups (-1.44 +/- .19 to -1.82 +/- .17%). The pure pancreas preservation failure rates with machine perfusion were between 30% and 40% at 24 to 48 hours, compared to 0% in those simply stored in cold SGF for 24 to 48 hours. We conclude that pancreas preservation by cold storage in high osmolar silica gel filtered plasma is more reliable than pulsatile machine perfusion and provides sufficient time to complete the logistical maneuvers necessary for clinical pancreas transplantation from cadaver donors.     

Treatment of rat heart allograft recipients with postoperative total lymphoid irradiation (TLI)

Pretransplant total lymphoid irradiation (TLI) plus donor bone marrow can result in donor-specific tolerance, but graft-versus-host disease is not consistently avoided. TLI may have greater applicability as an adjuct to generalized immunosuppressive treatment. In a clinical trial, preoperative TLI posed problems for patients with a high percentage of cytotoxic antibodies who sometimes had a long wait for a transplant after completion of TLI. It would be logistically advantageous if TLI could be given in the perioperative period. We investigated the feasibility of this approach in an ACI (RT-1^a) to Lewis (RT-1^l) rat heart allograft model. Untreated recipients rejected the grafts at a mean of 6.1 days. TLI 400 or 600 rads administered as one dose 1 day preoperative did not prolong graft survival (rejected a mean of 5.6 and 6.3 days). A dose fraction schedule previously found to be effective when given preoperatively, 200 rads × 5 consecutive days, did not prolong graft survival when administered beginning the first day postoperatively (mean rejection at 6.3 days). Higher dose fractions were effective: 300 rads × 3, 300 rads × 5, 400 rads × 3, and 400 rads × 4 gave mean rejection times of 11.8, 16.8, 11.5, and 13.6 days, respectively. Combining 600 rads preoperative with 200 rads × 5 days postoperative did not prolong graft survival. Six hundred rads preoperative plus 300 rads × 3 days postoperative prolonged graft survival, but was no more effective than 300 rads × 3 days postoperative alone. The most effective schedule for postoperative TLI was 300 rads × 3, 0 rads × 2, and 200 rads × 5 days; this treatment delayed rejection to 25 days. In conclusion, one dose preoperative TLI has no effect on heart allograft survival, but postoperative TLI in dose fractions of 300 rads is effective in delaying rejection. Postoperative TLI may be an alternative treatment for patients who must wait for suitable crossmatch negative cadaver kidneys.     

Effect of a cyclic hexapeptide analog (L363,586) of somatostatin on the function of pancreas grafts in dogs

Complications related to the exocrine secretions cause some pancreas grafts to fail in the early postoperative period. Somatostatin inhibits exocrine secretion, as well as insulin and glucagon release. L363,586 is a cyclic hexapeptide analog of somatostatin that is 50 to 100 times more potent than the native hormone in inhibiting islet hormone release. In a preliminary experiment in which permanent fistulas were created in two dogs, we demonstrated that L363,586 (0.3 micrograms/kg/60 min) results in a fourfold decrease in pancreatic exocrine secretion when measured for 210 min following a beef meal. In a separate experiment, five totally pancreatectomized dogs who received segmental pancreas autografts with pancreaticoductocystostomy 10 months previously had L363,586 (0.3 micrograms/kg/hr) administered by the Alzet osmotic pump subcutaneously for 7 days. Mean (+/-SE) daily serum amylase activity (IU/dl) during the week before the implant was 78 +/- 3, during the week of infusion was 65 +/- 2 (P less than 0.001), and during the week afterward was 76 +/- 2. In a prospective experiment, 12 totally pancreatectomized dogs received segmental pancreas autografts with anastomosis of the graft vessels to the iliac vessels and of the pancreatic duct to the bladder. L363,586 was administered by osmotic pump for 7 days to seven dogs at a dose of 0.3 micrograms/kg/hr. Mean (+/-SE) daily serum amylase levels at 1, 2, and 3 weeks posttransplant were 223 +/- 17, 81 +/- 3, and 82 +/- 5 in the L363,586-treated dogs and 229 +/- 18, 108 +/- 5, and 90 +/- 5 in the five untreated dogs (P less than 0.001 at 2 weeks).(ABSTRACT TRUNCATED AT 250 WORDS)     

Cell-free supernatant from hepatocyte cultures improves survival of rats with chemically induced acute liver failure

Current support or replacement therapies for fulminant hepatic failure are frequently inadequate. Hepatocyte transplantation has been found to permit or facilitate recovery from chemically induced liver failure in rats. The mechanisms are unclear, but function of the transplanted cells or stimulation of host liver regeneration by factors released from the cells could improve survival; there is evidence from experiments by other investigators using cell fractions to support the latter hypothesis. We compared intact cells and the supernatant from cultured liver cells for their influence on the survival of Fischer male rats with d-galactosamine (d-Gal) induced acute liver failure (ALF). All treatments were given 20 to 24 hr after poisoning. Cell supernates were injected intrasplenically (sp), intraperitoneally (ip), or intravenously (iv). Liver cells (2 × 10⁷) suspended in Hanks' solution were injected intrasplenically. Untreated rats and rats treated with Hanks' solution or culture medium alone had a 94–100% mortality, with all deaths occurring between 38 and 74 hr after poisoning. Improved survival was seen in all experimental groups: 47% of the rats receiving intact liver cells survived; 50, 55, and 62% of the rats receiving cell-free supernate by the sp, ip, or iv routes, respectively, survived. A chronologic electron micrographic study of livers from rats serially sacrificed in parallel experiments showed that recovery from morphological changes induced by d-Gal occurred in treated rats. These studies demonstrate that intact hepatocytes are not required to improve survival in rats with drug-induced ALF. Improved survival may be achieved by factors liberated by cultured hepatocytes that enhance the regeneration of the damaged liver. Supernatant from cultured liver cells may have a therapeutic potential in acute hepatic failure.     

Differences in susceptibility to rejection of mouse pancreatic islet allografts disparate for class I or class II major histocompatibility antigens

Pancreatic islet B cells express class I but not class II antigens, and removal of Ia positive passenger cells from H-2 allogeneic islets by anti-Ia serum and complement leads to permanent allograft survival. A test was made of whether the same result can be achieved by genetically removing the Ia stimulus by performing mouse islet allografts in congenic donor-recipient combinations differing at the H-2 K only, D only, or K + D regions. Mice disparate for class I antigens (H-2 K, D, and K + D) alone reject islet allografts, suggesting that Ia positive passenger cells may be involved in presentation of class I disparities. Established islet allografts appear to be sensitive to rejection induced by injection of donor strain splenocytes when donor and recipient differ for class I (H-2 D alone and D + I) but not class II (H-2 I alone) antigens. These results are consistent with the hypothesis that pancreatic islet allografts do not express class II target antigens, but do express class I antigens that in long-established pancreatic islet allografts are capable of acting as targets but not in initiating an immune response.     

Prevention of ATP catabolism during myocardial ischemia: A preliminary report

The enhancement of ATP regeneration following global myocardial ischemia in dogs by both ATP catabolic enzyme blockade and precursor infusion was investigated. The breakdown of AMP to adenosine is catalyzed by 5′-nucleotidase and this enzyme was inhibited during the ischemic period with either concanavalin A (Con A, 3 mg/kg) or α,β-methyleneadenosine 5′-diphosphate (AMP-CP, 250 μM). To provide additional ATP precursors, adenine (30 mg/kg) and ribose (25 mg/kg) (A/R) were also infused into the coronary vasculature during ischemia and recovery on cardiopulmonary bypass. Left ventricular myocardial ATP levels in control animals decreased to 52% of preischemic values during aortic cross clamping, but ATP levels in dogs treated with AMP-CP + A/R fell to only 67% of preischemic values (P < 0.05). During reperfusion, ATP levels in Con A + A/R (3.43 ± 0.26 μmole/g wet wt) and AMP-CP + A/R (3.77 ± 0.42) treated animals were higher than values found in control dogs (2.73 ± 0.16, P < 0.05). Infusions of A/R alone without enzyme inhibition did not increase ATP regeneration. The adenine nucleotide energy charge ratio was also increased by enzyme blockade with either inhibitor when combined with precursor infusion. On bypass, left ventricular myocardial blood flow (measured by the microsphere technique) was increased by 140% (P < 0.01) over control values in all groups receiving A/R; therefore, enhanced ATP levels were not merely the result of increased flow. Renal blood flow was not adversely affected by this combination of drugs as has been previously found with adenosine infusion and inhibition of adenosine catabolism.     

Enhanced cardiac efficiency with dobutamine after global ischemia

Dopamine and dobutamine are used in low output states following cardiopulmonary bypass but the consequences of increased inotropic activity on myocardium recovering from ischemia is unknown. Dogs on cardiopulmonary bypass were subjected to 20 min of normothermic global ischemia followed by 20 min of reperfusion. Dopamine or dobutamine (both at 10 μg/kg/min) or normal saline infusion was begun and 10 min later the dogs weaned from cardiopulmonary bypass while the infusions continued. Serial measurements were made of regional myocardial and systemic blood flow (15 μm radiolabeled spheres), myocardial oxygen consumption, creatine phosphate, and ATP levels. On bypass mean aortic pressure was decreased and heart rate, oxygen consumption, and left ventricular blood flow were increased by both catecholamine infusions (P < 0.01), but neither drug lowered ATP or creatine phosphate levels. Renal blood flow was decreased in dobutamine-treated dogs (P < 0.01). Off bypass, heart rate and mean aortic pressure were similar in all groups. While both drugs increased left ventricular blood flow to a similar extent (P < 0.01), dopamine treatment raised cardiac output by only 30% (P < 0.05) and dobutamine treatment increased cardiac output by 85% (P < 0.01). In addition, myocardial oxygen consumption was increased in dopamine-treated dogs (P < 0.05) while values in dobutamine animals were similar to controls. Therefore, dobutamine seems advantageous to dopamine following bypass because it increases cardiac output (by increasing stroke volume) but does not increase myocardial oxygen consumption. Both drugs are potentially detrimental on bypass because they greatly increase heart rate and oxygen consumption and, in addition, dobutamine causes an unexplained fall in renal blood flow.     

Technical aspects of segmental pancreatic autotransplantation in dogs

Heterotopic segmental pancreatic autotransplantation in dogs is more appropriate than allograft models for the investigation of several problems associated with transplantation. We have defined the anatomic variations of blood supply in the pancreatic tail and designed various modifications of vascular anastomosis to the iliac vessels in order to eliminate technical failures, such as thrombosis, as much as possible. In 187 of 240 dogs (77.9 percent), the pancreatic artery originated from the splenic artery and the pancreatic vein entered the splenic vein (normal anatomy). The main venous variation was direct confluence of the pancreatic and portal veins (12.1 percent), and the main arterial variation was origin of the pancreatic artery from the superior mesenteric artery (10 percent). Ninety-seven animals with normal anatomy qualified for a comparative study of seven methods of segmental pancreatic autotransplantation. Venous anastomoses were always performed in an end-to-side fashion between the splenic and external iliac veins. Arterial anastomosis techniques follow. Group I: interposition of the splenic artery into the external iliac artery; (14 days, failure rate 50 percent), Group II: end-to-end arterial anastomosis of the splenic artery to a long external iliac artery segment with the graft directed caudad, resulting in an acute curve to the vessel loop (8 dogs, failure rate 38 percent); Group III: end-to-end arterial anastomosis to a long external iliac artery with the graft directed cephalad, resulting in a gentle curve to the vessel loop (11 dogs, failure rate 36 percent); Group IV: end-to-end arterial anastomosis to a short external iliac artery stump (20 dogs, failure rate 20 percent); Group V: same as in Group IV with the addition of a distal splenic arteriovenous fistula (12 dogs, failure rate 17 percent); Group VI: end-to-side anastomosis of the splenic artery to the external iliac artery (31 dogs, failure rate 6 percent); Group VII: same as in Group VI but with the addition of an arteriovenous fistula of the distal splenic vessels (1 dog, failure rate 0). The end-to-side technique proved to be straight-forward and reliable. The low failure rate with this method allows metabolic preservation and other aspects of pancreatic transplantation to be studied and the results to be interpreted without the influence of a high complication rate from the operation itself.     

Endocrine function and histology of the canine pancreas after exocrine ablation by ductal injection of silicone rubber adhesive

Ablation of pancreatic exocrine tissue by intraductal injection of silicone rubber is a potential method for obviating the need to drain exocrine secretions after pancreas transplantation. Silicone rubber adhesive was injected into the pancreatic duct of eight dogs. After an initial rise in serum amylase, levels returned to normal. All dogs remained normoglycemic, although glucose tolerance tests were slightly abnormal at 1 and 2 months. Biopsies at 6 and 12 weeks showed marked atrophy of the pancreases, with involution of acini and fibrosis; islets and β cells were preserved. Silicone rubber injection induces exocrine atrophy without chronic inflammation or a significant loss of β-cell function.     

Rejection of established mouse pancreatic islet allografts by active immunization requires class I (H-2 K, D) antigen disparities

In certain donor-recipient mouse strain combinations with class I (H-2 K, D, and K + D) or with classes I and II (H-2 D + I) disparities the incidence of islet allograft rejection is low. Furthermore pancreatic islet allografts transplanted between strains with class II (H-2 Ia) differences alone are rarely acutely rejected. In this experiment the ability of donor strain or third-party allogeneic splenocytes (active immunization) to induce rejection of established (greater than 100 days) islet allografts when the donor and recipient differed only for class I or class II antigens was tested. Class I disparate islet allografts are rejected if challenged with donor or third-party allogeneic splenocytes. The frequency of rejection is similar (80-89%) if the third-party splenocytes share the class I allele with the islet donor strain. In contrast, class II disparate islet allografts are not rejected after challenge with donor splenocytes or third-party splenocytes even when the third-party strain shares the class II disparity with the islet donor strain as well as class I antigens common to the donor and recipient. Furthermore, rejection of class II disparate islets did not occur following passive transfer of recipient strain splenocytes sensitized in vitro to donor strain lymphocytes. These results show that rejection of established islet allografts can only be induced if (1) the islet graft expresses H-2 K or H-2 D gene products that are different than the recipient strain, i.e., only class I antigens can serve as targets; and (2) challenging splenocytes also have class I disparities with the recipient.     

The role of heparin in guinea pig gram negative bacterial sepsis

The ability of antibody directed against shared antigenic determinants of gram negative organisms to protect against a challenge of diverse gram negative bacterial species remains controversial in the experimental setting. Attention has focused, however, on the use as immunogens of rough mutants of Escherichia coli and Salmonella minnesota, which express a portion of core lipopolysaccharide (LPS) extensively on their cell surface. Core LPS is a structure present on the outer membrane of most, if not all, gram negative bacteria. In this study rabbits were immunized with E. coli J5, a rough mutant of E. coli, to produce anti-E. coli J5 rabbit antiserum (anti-J5 RS). Anti-J5 RS was found to cross react extensively by enzyme-linked immunosorbent assay with various gram negative bacterial whole cell or LPS antigens, compared to normal rabbit serum (NRS). Anti-J5 RS +/- heparin was also compared to NRS +/- heparin pretreatment in a guinea pig model of sepsis utilizing E. coli O111:B4 as the challenge organism. Anti-J5 RS +/- heparin augmented systemic bacterial clearance compared to NRS +/- heparin, but only the combination of anti-J5 RS and heparin enhanced survival 48 hr after bacterial challenge. It was concluded that pretreatment with anti-J5 RS was a necessary, but not sufficient condition for enhanced survival, and that the addition of heparin to anti-J5 RS pretreatment might diminish the otherwise lethal consequences of complement activation and disseminated intravascular coagulation in this model system.     

Delayed-type cutaneous hypersensitivity to Thomsen-Friedenreich (T) antigen in patients with pancreatic cancer

The delayed-type hypersensitivity skin reaction to human erythrocyte-derived Thomsen-Friedenreich (T) antigen was studied in 40 patients with pancreatic disease and in 158 control subjects and its sensitivity and specificity were compared with the carcinoembryonic antigen (CEA) blood levels. The skin reaction to T was positive in 22 of 25 patients with biopsy-proven adenocarcinoma of the pancreas (sensitivity, 88%). In these patients, the CEA levels were elevated above 3.5 ng/ml in 12 of 23 (52%). The skin test to T antigen was negative in 11 of 12 patients with chronic pancreatitis (specificity, 92%), but CEA levels were normal in only five of nine with pancreatitis (56%). Two of the patients with pancreatic carcinoma and one of those with pancreatitis were anergic to mumps and dermatophytin antigens and had thus an invalid skin test. The positive response rate to T antigen was significantly greater (P less than 0.005) in the cancer group than the group with pancreatitis; the CEA response was not significantly different. There were no positive responses to T in 82 healthy volunteers. Among 76 patients with chronic disease including six with malignant tumors of the mesoderm and central nervous system, there were four positive responses: two in heavy smokers and two in patients with chronic lung infection. The specificity of the test overall in 158 controls was thus 97.5%.     

Cold storage of segmental canine pancreatic grafts for 24 hours

The feasibility of cold storage of pancreatic segments for 24 hr was studied in a dog autograft model. Two groups of dogs were studied. In Group 1 n = 9) the tail of the pancreas was removed with its vascular pedicle, flushed with lactated Ringer's solution, and immediately transplanted intraperitoneally to the left iliac vessels. The pancreatic duct was left open. The grafts in Group 2 (n = 9) were flushed and stored at 4°C in Collins solution for 23 to 25 hr prior to transplantation. Total pancreatectomy was performed in all animals at the time of transplantation. Seven animals in Group 1 and five animals in Group 2 underwent intravenous glucose tolerance tests (0.25 g/kg) on the seventh postoperative day. Mean glucose values at all time points were not significantly different. Mean (±SEM) K values were 1.36 ± 0.12% for Group 1 and 1.24 ± 0.17% for Group 2. Serum insulin concentrations (basal and peak) increased from 7 ± 1 to 30 ± 4 μU/ml in Group 1 and from 11 ± 2 to 35 ± 6 μU/ml in Group 2 during glucose tolerance testing, a similar response. In all dogs of both groups surviving for over 1 week, plasma glucose was in the normal range (71–146 mg/dl) immediately after transplantation and stayed within physiologic limits (65–155 mg/dl) throughout the follow-up period (1–10 months). Two dogs in each group died of vascular complications that were clearly secondary to technical difficulties at the time of transplantation. Two dogs in Group 2 died of complications (one peritonitis, one respiratory failure) in which the transplant may have been a contributing factor. Histologic and electron microscopic studies of stored grafts from biopsies taken before, during, and after 24 hr of cold storage and transplantation showed normal pancreatic architecture, no changes in islets, and minimal changes in the exocrine pancreas. In acinar cells a dilation of the cisternae of the rough endoplasmic reticulum and an increase in mature and immature zymogen granules could be demonstrated. Six hours after transplantation the acinar cells looked normal, showing that the morphologic manifestations of injury were reversible. We conclude that 24 hr cold storage in Collins solution at 4°C is a reliable method for preservation of pancreatic grafts. If this technique can be applied to human pancreases, it will simplify the logistical aspects of clinical pancreas transplantation.     

Hepatocellular transplantation for experimental ischemic acute liver failure in dogs

Recovery from acute liver failure is possible if metabolic support can be provided during the period of exogenous liver regeneration. The ability of transplanted dispersed autologous hepatocytes to alter the course of experimental ischemic acute liver failure in dogs was tested. Liver failure was induced by occlusion of blood flow in the proximal portal vein and hepatic artery(s) 48 hr after creation of a side to side portacaval shunt and immediately after a left lateral hepatic lobectomy. Dogs in Group 1 had ischemic injury with no treatment. Dogs in Group II received intrasplenic autotransplants of hepatocytes (26 ± 4x × 10⁸ intact cells) after the ischemic period. Cells for transplantation were prepared from the excised lobe during the period of liver ischemia. Dogs in Group III received intrasplenic transplants of autologous hepatocytes (26 = 3 × 10⁸ intact cells) after liver ischemia and after ligation of the main splenic artery. Serum bilirubin, serum glutamic oxalocetic transaminase, lactate dehydrogenase, and alkaline phosphatase were measured before and serially after ischemia, and showed that the degree of liver injury in all three groups was similar, although survival in Group III was better. Only 20% of nontransplanted animals (Group I) survived 10 days. Liver histology in animals that died showed hemorrhagic necrosis situation around the terminal hepatic central veins. Transplantation did not improve survival in dogs with arterialized spleens and histological examination of dogs that died showed pulmonary infarcts and additional liver injury from embolization of hepatocytes. In contrast, 70% of the animals undergoing splenic artery ligation before intrasplenic transplantation of hepatocytes were alive at 10 days. Ligation of the splenic artery reduced the tendency for hepatocytes to escape into the splenic vein and the spleen remained viable due to collateral circulation. On histological examination, hepatocytes were readily identified in the splenic parenchyma at 24 hr. 2 and 4 weeks after transplantation. In conclusion, intrasplenic hepatocytes provide sufficient metabolic support for dogs to recover from otherwise lethal ischemically induced, acute liver failure.     

The relationship of lumenal pH and distention to antral G-cell numbers

This study was designed to study the importance of lumenal pH and antral distention on G-cell numbers. Antrocolic transpositions (ACT) were performed in female Sprague-Dawley rats, orienting the peristalsis of the transposed antra to result in either filling or emptying. In some animals a segment of parietal cell bearing corpus mucosa was left with the antrum to provide a relatively acid lumen. Sham operations were performed in controls. The rats were sacrificed after 15 days. The self-filling antra were grossly distended compared with the self emptying antra. G cells were quantitated by means of a double-antibody immunofluorescence technique. All ACT rats had significantly increased G-cell numbers and serum gastrin levels compared with controls. The magnitude of the increase depended on the presence or absence of distention and an acid environment. The most marked hyperplasia occurred in the group with distended antra and no acid. The group with self-filling antra but an acid lumen showed a significant but lesser increase. The least degree of hyperplasia was observed in the group with self-emptying antra and an acid lumen. These data indicate that both distention and a nonacid lumenal pH encourage G-cell hyperplasia. The nonacid lumen is a more potent stimulus than distention but the two are synergistic.     

Rejection of islets versus immediately vascularized pancreatic allografts: a quantitative comparison

It has been suggested that free grafts of islets are rejected more vigorously than immediately vascularized intact organs grafts. However, the physiological manifestations of rejection depend, in part, upon the functional reserve of the transplanted tissue. If the number of islets transplanted is just adequate to maintain normoglycemia, the immune destruction of only a few islets will be manifested by hyperglycemia. Thus, differences in rejection time could be an artifact of the islet mass transplanted. We compared the onset of rejection of immediately vascularized segmental pancreatic grafts and of free grafts of islets under conditions in which the β cell mass transplanted, as determined by tissue insulin content, was equivalent. Lewis rats, made diabetic (plasma glucose > 400 mg/dl) by streptozotocin, received either free islet allografts by portal embolization or vascularized segmental pancreatic allografts derived from Fischer donors. Identical pancreatic segments that were not transplanted had a mean (± SE) total tissue insulin content of 33 ± 3 μg. The mean total insulin content of Fischer islets prepared by collagenase digestion in a quantity identical to that used for transplantation to single recipients was 35 ± 7 μg. Similar measurements were made in Fischer to Fischer and Lewis to Lewis isograft control groups. Recipients of both segmental pancreas and free islet grafts became normoglycemic after transplantation and this state was sustained indefinitely in recipients of syngeneic grafts. In rats receiving allografts, the day of rejection, defined as an elevation of plasma glucose to >200 mg/dl, occurred at a mean of 12.1 ± 0.3 days for recipients of pancreatic grafts (n = 17) and 5.2 ± 0.3 days in recipients of islet grafts (n = 17) (P < 0.001). The functional survival of free grafts of allogeneic islets is less than that of islets contained within immediately vascularized pancreatic grafts, even when the transplanted β cell mass is equivalent. However, this difference could still be due to nonimmunologic, quantitative factors that influenced the rate with which hyperglycemia occurred after initiation of the rejection process. The insulin content in the livers of islet isograft recipients showed that only 53 to 71% of the transplanted islets survived. Further experiments that compensate for this factor are needed to determine whether or not there are differences in susceptibility to rejection of the two types of grafts. Nevertheless, on the basis of the number of donors used per recipient, islet allotransplantation is less efficient than pancreas allotransplantation.     

Placement of pericardial drainage tube for the treatment of pneumopericardium in the neonate

A method for resolving the life-threatening complication of neonatal pneumopericardium is described. In patients suspected of having this complication, needle aspiration of the pericardial sac should be performed to confirm the diagnosis. Then a tube should be inserted directly into the sac, attached to continuous-suction drainage, and allowed to remain in place until positive end-expiratory pressure is discontinued. The technique has not been associated with morbidity, mortality, or recurrence of pneumopericardium.     

Pulmonary Valve Replacement with a Porcine Aortic Heterograft

Pulmonary valve replacement is an uncommon surgical procedure, yet lifesaving when performed under the appropriate circumstances. The patient reported on here had the classic indications for valve replacement: increased pulmonary vascular resistance and associated pulmonary valve incompetence following repair of a congenital heart defect resulting in right heart failure and secondary tricuspid insufficiency. A review of the literature provides the basis for the decision to replace the pulmonary valve with a glutaraldehyde-preserved porcine heterograft.     

The technique of the Fontan procedure with posterior right atrium-pulmonary artery connection

A detailed technique is described for use of a modified Fontan procedure applicable to transposed as well as nontransposed anatomy. In the modified procedure, the use of circumferential grafting is eliminated, as are the complications arising from an anterior conduit in front of the aorta. Clinical results are reported for 9 young adults undergoing this operation.     

Total lymphoid irradiation: Critical timing and combination with cyclosporin A for immunosuppression in a rat heart allograft model

Total lymphoid irradiation (TLI), a standard radiotherapeutic technique for the treatment of Hodgkin's disease, is immunosuppressive. TLI has been used for clinical renal transplantation in conjunction with pharmacological immunosuppression. The optimal recipient treatment protocol is not known. Using ACI (RT-1^a) rat heart allograft survival in Lewis (RT-1¹) rat recipients as a measure of treatment efficacy, we have determined the importance of radiation fractionation, the optimum dose per radiation fraction, the effect of delaying transplantation after completion of TLI, the effect of pretransplant versus post-transplant TLI, and the effect of combining TLI with a pharmacological immunosuppressant, cyclosporin A (CsA). Median heart allograft survival in untreated rats, in rats given 1000 rad (single dose), and in rats given 1000 rad in five fractions pretransplant were 6, 9, and 26 days, respectively. Median allograft survival in rats given 1000 rad in <5 or >5 fractions was 10–14 days. A dose fraction of between 125 and 250 rad was optimal. Heart allografts transplanted immediately after 2600 rad TLI (13 × 200 rad) survived 57 days; survival was shortened to 20 days if transplantation was delayed 1 month. Postoperative TLI alone did not prolong allograft survival. CsA (1.25 mg/kg/day) alone, in combination with preoperative TLI (5 × 200 rad), and in combination with postoperative TLI (9 × 200 rad) resulted in median survival times of 15, 96, and 60 days. Both the sequential and concurrent combination of TLI and CsA have synergistic effects on heart allograft survival. For optimal results, TLI should be fractionated preoperatively and transplantation should be performed soon after completion of radiotherapy. Post-transplant TLI is effective only if used in combination with pharmacological immunosuppression.