[Factors contributing to an increase in DLco (steady state) after exercise in healthy men].

We studied factors contributing to an increase of DLco (steady state) from rest to exercise in 10 healthy men. DLco(ss), Dm, and Vc were measured under three different conditions, rest, constant load exercise (50 watts), and hyperventilation (equal to the tidal volume and respiratory rate of exercise). DLco(ss) increased significantly during exercise and hyperventilation compared with at rest. DLco(ss) also increased significantly during exercise, compared with hyperventilation. During constant load exercise (50 watts) increased Dm and Vc, caused by increased ventilation, together with increased of Vc caused by increased of pulmonary blood flow resulted in an increase in DLco(ss).

Inhibition of platelet integrin GPIIbIIIa prolongs survival of discordant cardiac xenografts.

The integrin GPIIbIIIa is known to be crucial to the formation of platelet aggregates and potentiates adhesion to subendothelial matrices via fibrin(ogen), von Willebrand factor, and vitronectin. Given the demonstration by us and others of widespread platelet aggregation during xenograft rejection, we hypothesized that platelet thrombi might contribute to graft dysfunction during development of hyperacute rejection (HAR), as well as during what we have termed delayed xenograft rejection (DXR), e.g., as seen in complement-depleted rat recipients of guinea pig cardiac xenografts. We therefore tested the effects of a specific GPIIbIIIa antagonist (SDZ GPI 562) during xenograft rejection. Lewis rats received heterotopic guinea pig cardiac xenografts and were treated with GPI 562 alone (HAR model) or in combination with cobra venom factor (CVF) (DXR model). A high (0.5 mg/kg) or a low dose (0.1 mg/kg) of GPI 562 was administered perioperatively and then given twice daily in the same dose until rejection. CVF was given daily until rejection. Plasma drawn after the first dose of GPI 562 and at the time of rejection was tested for the ability to inhibit ADP-stimulated platelet aggregation in vitro. Rejected grafts were analyzed by immunohistology. Plasma from animals in the high-dose group completely inhibited platelet aggregation in vitro, whereas plasma from the low-dose group resulted in only partial inhibition. Similarly, whereas low-dose GPI 562 failed to prolong graft survival, high-dose GPI 562 showed a statistically significant increase in graft survival in both HAR and DXR groups. Immunohistologic studies of HAR showed little effect of GPI 562 on platelet aggregation or activation and no effect on fibrin deposition. However, the combination of high-dose GPI 562 and CVF resulted in a significant decrease in intragraft platelet aggregation, P-selectin expression, and leukocyte infiltration compared with CVF alone. In conclusion, GPIIbIIIa antagonist therapy can inhibit platelet aggregation in vitro and prolong xenograft survival. The diminution of intragraft platelet microthrombi formation and leukocyte infiltration suggests an important role for platelet-dependent mechanisms in leukocyte recruitment during DXR.

PGG-glucan, a leukocyte-specific immunostimulant, does not potentiate GVHD or allograft rejection.

PGG-glucan is an immunomodulator which can enhance the host response to infection. Phase I/II clinical trials have documented the safety and potential efficacy of this compound to reduce postoperative infectious complications in high risk surgical patients. Organ transplant recipients may benefit from this drug due to their high rates of postoperative infectious complications. A rat cardiac rejection model (ACI --> Lew) and a mouse skin graft model (C3H/HeJ --> B6AF1/J) were used with four treatment arms (control, Cyclosporine A (CsA), antilymphocyte serum (ALS), and CsA + ALS with and without PGG-glucan). Small intestinal allografts (Lew --> LBNF1) were performed in rats to evaluate GVHD. In the mouse GVHD model, donor splenocytes were given to irradiated recipients (C57BL/6 --> B6AF1), with and without PGG-glucan treatment. There was no difference in survival between PGG-glucan treatment and placebo for the control, CsA, and CsA + ALS groups in rat cardiac recipients. Recipients receiving ALS and treated with PGG-glucan survived a median of 42.5 days versus 63.5 days for those ALS-treated animals not receiving PGG-glucan (P = 0.045). In the remaining groups there was no difference in survival between PGG-glucan-treated groups and the control groups. PGG-glucan did not shorten survival in three of four treatment groups in the rat cardiac rejection model. High dose ALS with PGG-glucan did result in a marginal decrease in survival in cardiac allograft recipients. If the one outlying animal with indefinite survival is excluded, the difference is not statistically significant (P = 0.098). These results show that even though PGG-glucan has immunostimulatory properties, it does not significantly potentiate rejection or GVHD in these animal models. This preliminary work may be important in determining whether PGG-glucan can be safely given to immunosuppressed organ transplant recipients to reduce postoperative infectious complications.

Treatment of diabetes by xenogeneic islets without immunosuppression. Use of a vascularized bioartificial pancreas.

Tight glycemic control by intensive insulin therapy effectively delays the onset and slows the progression of diabetic complications but is associated with frequent dose adjustments and a high incidence of hypoglycemia. Successful pancreas transplantation corrects abnormal glucose metabolism but subjects patients to morbidity and mortality associated with chronic immunosuppression. A vascularized artificial pancreas device containing pancreatic islets is designed to provide glycemic control without immunosuppression. We report here that devices seeded with porcine islets implanted into pancreatectomized severely diabetic dogs maintained a marked improvement in glycemic control with reduced exogenous insulin requirements for up to 9 months with improved glucose tolerance and a reduction in glycosylated hemoglobin levels. No immunosuppression was used. Thus, use of a vascularized artificial pancreas containing xenogeneic porcine islets could be an alternative to intensive insulin therapy and pancreatic transplantation in treating diabetic patients before the development of severe diabetic complications.

Marked prolongation of rat skin xenografts induced by intrathymic injection of xenogeneic splenocytes and a short course of rapamycin in antilymphocyte serum-treated mice.

The effect of intrathymic (IT) injection of donor splenocytes and a short course of rapamycin (Rapa) treatment on rat to mouse skin xenograft survival was investigated. ACI rat skin xenografts were transplanted to (C57BL/6 x A)F1 mice treated with rabbit anti-mouse lymphocyte serum (ALS) on days -1, +2, and +4 relative to skin grafting on day 0. Fifty million donor-type splenocytes were injected intrathymically on day 7 after transplantation. Rapa was given intraperitoneally every other day from day 0 to day 12 at a dose of 3.0 mg/kg. Prolonged skin xenograft survival was observed in ALS- and Rapa-treated recipients (no IT injection) with a median survival time of 47 days. However, skin graft survival was markedly more prolonged in the group treated with ALS, Rapa, and IT injection of donor splenocytes did not have a beneficial effect on skin xenograft survival in ALS-treated recipients. An increased presence of donor-type cells was observed in the thymus of the ALS- and Rapa-treated recipients for 7 days after IT injection of donor splenocytes. In conclusion, a short course of Rapa markedly augments rat skin xenograft survival in ALS-treated mice injected intrathymically with donor-type splenocytes.

Long-term effects of intrasplenically transplanted adult hepatocytes and fetal liver in hyperbilirubinemic Gunn rats.

We performed adult hepatocyte transplantation (HCTx) and fetal liver transplantation (FLTx) into the spleens of hyperbilirubinemic Gunn rats in congenic combination and we compared the long-term effects of these procedures for as long as 12 months. Proliferative activity of intrasplenic hepatocytes was evaluated using antiproliferating cell nuclear antigen (PCNA) immunohistochemical staining. The serum total bilirubin levels (T. Bil) significantly decreased from 7.16 +/- 0.25 mg/dl to 4.38 +/- 0.60 mg/dl 2 months after HCTx and gradually decreased thereafter until 12 months after transplantation (3.23 +/- 0.37 mg/dl, P < 0.05 vs preoperative value). The T. Bil change after FLTx was similar to that of HCTx: 7.22 +/- 0.24 mg/dl before FLTx, and 4.92 +/- 0.24 and 3.06 +/- 0.47 mg/dl, 2 and 12 months after FLTx (P < 0.05), respectively. Bilirubin glucuronides, which were not detectable in the bile from untreated Gunn rats, appeared in considerable amounts 4 months after HCTx and FLTx (27.5% and 36.0% of total bile, respectively). PCNA labeling indices of intrasplenic hepatocytes (4.9% +/- 0.9% and 3.7% +/- 0.7%, 6 months after HCTx and FLTx, respectively) were slightly higher than those of normal hepatocytes (1.0% +/- 0.1%) in the host liver. In conclusion, both adult and fetal rat hepatocytes transplanted into the spleen in congenic combination functioned for at least a year in terms of bilirubin glucuronidation. The spleen is considered to be one of the optimal grafting sites for hepatocytes, with nearly lifelong significant function and proliferative activity.

[Thallium-201 and gallium-67 scintigraphies in the diagnosis of pneumoconiosis combined with lung cancer].

Thallium-201 (201Tl) and Gallium-67 (67Ga) scintigraphies were performed on 62-year-old male with silicosis combined with lung cancer (squamous cell carcinoma). In 67Ga and early 201Tl images, radiotracer uptakes were observed in both sites of cancer and silicosis, and thus, it was impossible to differentiate cancer mass from the large opacity of pneumoconiosis. On the other hand, in the 201Tl delayed images, 201Tl was localized only in cancer mass, while it was washed out from the large opacity. Our findings indicated that 201Tl early and delayed scintigraphy findings were very useful to differentiate lung cancer from silicosis.

Hepatic support by hepatocyte transplantation in congenitally metabolic diseased rats.

Nagase analbuminemic rats (NAR), which lack albumin synthesis in the liver, underwent intrasplenic hepatocyte transplantation (HCTx), and the long-term effects were studied using functional and morphological examinations. Hepatocytes were isolated from congenic F344 rats with collagenase infusion, and 1 x 10(7) cells were injected into the spleen of 3-month-old NAR (n = 10). Serum albumin increased with time, reaching 53.9 mg/dl 14 months after HCTx, which was equivalent to 2.1% (maximum 4%) of serum albumin in normal rats. On the other hand, untreated NAR showed persistently low serum albumin levels (0.99 +/- 0.23 mg/dl at 10 months). According to immunostaining with anti-rat albumin antibody at 16 months after HCTx, hepatocyte grafts occupied 27-41% of the spleen area and weighed 120-420 mg, which was equivalent to 0.8-2.9% of a whole liver. Our study demonstrated that grafted hepatocytes can grow in the spleen with the ability to synthesize albumin. HCTx in NAR is a new experimental system to monitor the function and survival of grafted heptocytes without sacrificing the animals by measuring serum albumin levels. Certain manipulations to facilitate the growth of grafted hepatocytes are necessary to achieve sufficient hepatic support in HCTx.

New immunosuppression with monoclonal antibody to intracellular adhesion molecule 1 (ICAM-1) in rat organ transplantation.

Inbred, male Lewis rats underwent heterotopic heart allografting from F344 donor rats, or streptozocin (STZ)-induced diabetic Lewis rats underwent pancreas allografting with bladder drainage from F344 or ACI donor rats. A monoclonal antibody (MoAb) to intracellular adhesion molecule 1 (ICAM-1) was given i. p. (1.0 mg/kg) for 10 days, and its immunosuppressive potency was evaluated. The mean survival time (MST) of the heart allografts was significantly prolonged in the MoAb-treated group. Both exocrine and endocrine MST of pancreas allografts were also prolonged by MoAb administration across the minor and major histocompatibility barriers. However, complete graft tolerance was not induced. Our study demonstrated that the MoAb to ICAM-1 alone can delay the allograft rejection in rat organ transplantation.

Cell-mediated cytotoxicity in acute rat cardiac allograft rejection: an immunological and ultrastructural study.

To clarify the immune mechanism of cytotoxicity in acute cardiac allograft rejection, we observed interactions between cardiocytes and mononuclear cells using immunohistochemistry and light and electron microscopy. All allografted WKA rat hearts transplanted to F344 recipients stopped beating by the 7th day after the transplantation. The population of helper/inducer T cells (Th) and IL2R+ cells was large for the first 3 days, whereas that of cytotoxic/suppressor T cells (Tc-s) and macrophages increased from the 4th day. The Th/Tc-s ratios were more than 2.0 until the 3rd day, then decreased to less than 1.0. In circulating T lymphocytes; the Th/Tc-s ratios were under 1.0 on the 1st, 6th and 7th days. Electron microscopically IL2R+ cells, Tc-s and macrophages were often seen in close contact with the plasma membrane of the cardiocytes. The majority of IL2R+ cells are NK cells, Tc-s and Th. Of these, the population of Tc-s was small until the 3rd day. Thus, NK cells play a pivotal role in the early stage of the rejection, and Tc-s and macrophages then aggravate cell-mediated cardiocyte injury.

Experience in rat pancreas transplantation at Meikai University.

A review of rat pancreatic transplantation conducted at Meikai University is presented. It was found that pancreas transplantation normalized the endocrine based metabolic disturbances of diabetes. Arginine-induced serum insulin, glucagon, and somatostatin responses in the grafted pancreas were similar to those in normal pancreas. Urine amylase was found to be a more sensitive marker in graft rejection as compared with blood glucose using a urinary drainage model. The value of pancreas transplantation in diabetic nephropathy was dependent upon the timing of the transplantation; performed early in the course of diabetes (less than 4 months, post-diabetes), it was able to reverse the nephropathy.