Age-Dependent Metabolic and Immunosuppressive Effects of Tacrolimus.

Immunosuppression in elderly recipients has been underappreciated in clinical trials. Here, we assessed age-specific effects of the calcineurin inhibitor tacrolimus (TAC) in a murine transplant model and assessed its clinical relevance on human T cells. Old recipient mice exhibited prolonged skin graft survival compared with young animals after TAC administration. More important, half of the TAC dose was sufficient in old mice to achieve comparable systemic trough levels. TAC administration was able to reduce proinflammatory interferon-γ cytokine production and promote interleukin-10 production in old CD4+ T cells. In addition, TAC administration decreased interleukin-2 secretion in old CD4+ T cells more effectively while inhibiting the proliferation of CD4+ T cells in old mice. Both TAC-treated murine and human CD4+ T cells demonstrated an age-specific suppression of intracellular calcineurin levels and Ca2+ influx, two critical pathways in T cell activation. Of note, depletion of CD8+ T cells did not alter allograft survival outcome in old TAC-treated mice, suggesting that TAC age-specific effects were mainly CD4+ T cell mediated. Collectively, our study demonstrates age-specific immunosuppressive capacities of TAC that are CD4+ T cell mediated. The suppression of calcineurin levels and Ca2+ influx in both old murine and human T cells emphasizes the clinical relevance of age-specific effects when using TAC.

Fast Heating of Imploded Core with Counterbeam Configuration.

A tailored-pulse-imploded core with a diameter of 70 µm is flashed by counterirradiating 110 fs, 7 TW laser pulses. Photon emission (>40 eV) from the core exceeds the emission from the imploded core by 6 times, even though the heating pulse energies are only one seventh of the implosion energy. The coupling efficiency from the heating laser to the core using counterirradiation is 14% from the enhancement of photon emission. Neutrons are also produced by counterpropagating fast deuterons accelerated by the photon pressure of the heating pulses. A collisional two-dimensional particle-in-cell simulation reveals that the collisionless two counterpropagating fast-electron currents induce mega-Gauss magnetic filaments in the center of the core due to the Weibel instability. The counterpropagating fast-electron currents are absolutely unstable and independent of the core density and resistivity. Fast electrons with energy below a few MeV are trapped by these filaments in the core region, inducing an additional coupling. This might lead to the observed bright photon emissions.

Direct heating of a laser-imploded core by ultraintense laser-driven ions.

A novel direct core heating fusion process is introduced, in which a preimploded core is predominantly heated by energetic ions driven by LFEX, an extremely energetic ultrashort pulse laser. Consequently, we have observed the D(d,n)^{3}He-reacted neutrons (DD beam-fusion neutrons) with the yield of 5×10^{8} n/4π sr. Examination of the beam-fusion neutrons verified that the ions directly collide with the core plasma. While the hot electrons heat the whole core volume, the energetic ions deposit their energies locally in the core, forming hot spots for fuel ignition. As evidenced in the spectrum, the process simultaneously excited thermal neutrons with the yield of 6×10^{7} n/4π sr, raising the local core temperature from 0.8 to 1.8 keV. A one-dimensional hydrocode STAR 1D explains the shell implosion dynamics including the beam fusion and thermal fusion initiated by fast deuterons and carbon ions. A two-dimensional collisional particle-in-cell code predicts the core heating due to resistive processes driven by hot electrons, and also the generation of fast ions, which could be an additional heating source when they reach the core. Since the core density is limited to 2 g/cm^{3} in the current experiment, neither hot electrons nor fast ions can efficiently deposit their energy and the neutron yield remains low. In future work, we will achieve the higher core density (>10 g/cm^{3}); then hot electrons could contribute more to the core heating via drag heating. Together with hot electrons, the ion contribution to fast ignition is indispensable for realizing high-gain fusion. By virtue of its core heating and ignition, the proposed scheme can potentially achieve high gain fusion.

Comprehensive validation of early diagnostic algorithms for myocardial infarction in the emergency department.

OBJECTIVE: To comprehensively evaluate diagnostic algorithms for myocardial infarction using a high-sensitivity cardiac troponin I (hs-cTnI) assay. PATIENTS AND METHODS: We prospectively enrolled patients with suspected myocardial infarction without ST-segment elevation from nine emergency departments in Japan. The diagnostic algorithms evaluated: (i) based on hs-cTnI alone, such as the European Society of Cardiology (ESC) 0/1-h or 0/2-h and High-STEACS pathways; or (ii) used medical history and physical findings, such as the ADAPT, EDACS, HEART, and GRACE pathways. We evaluated the negative predictive value (NPV), sensitivity as safety measures, and proportion of patients classified as low or high-risk as an efficiency measure for a primary outcome of type 1 myocardial infarction or cardiac death within 30 days. RESULTS: We included 437 patients, and the hs-cTnI was collected at 0 and 1 hours in 407 patients and at 0 and 2 hours in 394. The primary outcome occurred in 8.1% (33/407) and 6.9% (27/394) of patients, respectively. All the algorithms classified low-risk patients without missing those with the primary outcome, except for the GRACE pathway. The hs-cTnI-based algorithms classified more patients as low-risk: the ESC 0/1-h 45.7%; the ESC 0/2-h 50.5%; the High-STEACS pathway 68.5%, than those using history and physical findings (15-30%). The High-STEACS pathway ruled out more patients (20.5%) by hs-cTnI measurement at 0 hours than the ESC 0/1-h and 0/2-h algorithms (7.4%). CONCLUSIONS: The hs-cTnI algorithms, especially the High-STEACS pathway, had excellent safety performance for the early diagnosis of myocardial infarction and offered the greatest improvement in efficiency.

Efficacy and safety of dapagliflozin as a monotherapy for type 2 diabetes mellitus in Japanese patients with inadequate glycaemic control: a phase II multicentre, randomized, double-blind, placebo-controlled trial.

AIM: Dapagliflozin is a selective sodium-glucose co-transporter 2 (SGLT2) inhibitor under development as a treatment for type 2 diabetes mellitus (T2DM). This study assessed the efficacy and safety of dapagliflozin monotherapy in Japanese T2DM patients with inadequate glycaemic control. METHODS: Patients (n = 279) were randomized to receive dapagliflozin (1, 2.5, 5 or 10 mg/day) or placebo once daily for 12 weeks. The primary endpoint was change from baseline in haemoglobin A1c (HbA1c) at week 12. Secondary endpoints included change from baseline in fasting plasma glucose (FPG) and proportion of patients achieving HbA1c <7.0% at week 12. RESULTS: Significant reductions in HbA1c were seen with all dapagliflozin doses (-0.11 to -0.44%) versus placebo (+0.37%). Reductions were also observed in FPG with dapagliflozin (-0.87 to -1.77 mmol/l [-15.61 to -31.94 mg/dl]) versus placebo (+0.62 mmol/l [+11.17 mg/dl]). No significant difference in the proportion of patients achieving HbA1c levels <7.0% was noted with dapagliflozin versus placebo. Adverse events (AEs) were more frequent with dapagliflozin (40.7-53.8%) versus placebo (38.9%) and were mostly mild/moderate in intensity. Three hypoglycaemic events were reported (1 each with placebo, dapagliflozin 2.5 mg and 10 mg). The frequency of signs and symptoms suggestive of urinary tract or genital infections was 0-3.8 and 0-1.8% respectively with dapagliflozin and 1.9 and 0% with placebo. No AEs of pyelonephritis were observed. CONCLUSIONS: Compared with placebo, dapagliflozin significantly reduced hyperglycaemia over 12 weeks with a low risk of hypoglycaemia in Japanese T2DM patients with inadequate glycaemic control.

Fusion using fast heating of a compactly imploded CD core.

A compact fast core heating experiment is described. A 4-J 0.4-ns output of a laser-diode-pumped high-repetition laser HAMA is divided into four beams, two of which counterilluminate double-deuterated polystyrene foils separated by 100 µm for implosion. The remaining two beams, compressed to 110 fs for fast heating, illuminate the same paths. Hot electrons produced by the heating pulses heat the imploded core, emitting x-ray radiations >20 eV and yielding some 10(3) thermal neutrons.

Adhesive interaction between peripheral blood mononuclear cells and activated platelets in the presence of anti-human leukocyte antigen Class I alloantibody causes production of IL-1ß and IL-8.

BACKGROUND: Activated platelets form heterogeneous aggregates of platelets and monocytes, which are involved in a variety of inflammatory disorders. Some anti-human leukocyte antigen (HLA) Class I antibodies have been shown to activate platelets. MATERIALS AND METHODS: Human leukocyte antigen-A2-positive or HLA-A2-negative platelets were incubated with HLA-A2-negative peripheral blood mononuclear cells (PBMNCs) in the presence of anti-HLA-A2 serum at 37°C. The binding of platelets to monocytes was analysed by flow cytometry. The levels of IL-1 ß and IL-8 in the culture supernatant were determined by ELISA. RESULTS: Anti-HLA-A2 serum increased the formation of aggregates between monocytes and HLA-A2-positive platelets, but not HLA-A2-negative platelets, in a dose-dependent manner. Antiserum also increased the number of platelets bound to monocytes in a time-dependent manner. The addition of anti-P-selectin glycoprotein ligand (PSGL-1) mAb almost completely inhibited the formation of platelet-monocyte aggregates as well as the number of platelets bound to monocytes. When HLA-A2-positive or HLA-A2-negative platelets were incubated with HLA-A2-negative PBMNCs in the presence of anti-HLA-A2, the level of IL-1ß and IL-8 in the supernatant of coculture was significantly higher in HLA-A2-positive platelets than in HLA-A2-negative platelets. The addition of anti-PSGL-1 mAb partially but significantly inhibited the production of both IL-1ß and IL-8. CONCLUSIONS: The activation of platelets with anti-HLA Class I alloantibody caused the formation of platelet-monocyte aggregates, followed by the production of IL-1ß and IL-8, in a cognate antigen-antibody manner. The adhesive interaction of P-selectin and PSGL-1 at least partially contributed to these phenomena.

Comparison between in vitro qualities of platelets washed with commercially available additive solutions and those washed with M-sol.

BACKGROUND AND OBJECTIVES: We previously developed a novel additive solution (M-sol) with a high ability to preserve the in vitro qualities of platelets (PLTs) in washed PLTs Here, we compared the ability of M-sol with that of commercially available additive solutions (ASs) to preserve the in vitro qualities (pH, mean PLT volume, %disc, P-selectin, %hypotonic shock response and aggregation) of PLTs at a low plasma concentration. MATERIALS AND METHODS: The platelet concentrate was divided into two equal aliquots (control group and test group). After centrifugation of both groups and removal of as much supernatant as possible, the pellet of the control group was resuspended in M-sol and those of the test group were resuspended in other ASs, and subsequently stored in polyolefin bags with agitating at 20-24 degrees C. RESULTS: Compared with those stored in M-sol, the qualities of PLTs stored in PAS-B (alternative name; PAS-II or T-sol), PAS- C (alternative name; PAS-III or Intersol) or Plasma Lyte were degraded as early as 24 h after washing. The qualities of PLTs stored in PAS-D (alternative name; Composol PS) or PAS-E (alternative name; PAS-IIIM or SSP+) were comparable to that of those stored in M-sol 24 h after washing; however, the qualities had deteriorated 72 h after washing. CONCLUSIONS: At a low plasma concentration (5% or less), the M-sol showed a higher ability to preserve PLTs than the five ASs studied here. Although PAS-D and PAS-E are available as an AS for short-term storage of washed PLTs, M-sol is thought to be preferable for longer storage.

Stimulation of human neutrophils with sera containing HLA Class I alloantibody causes preferential degranulation of azurophilic granules and secretory vesicles.

BACKGROUND AND OBJECTIVES: The activation of neutrophils by human leukocyte antigen (HLA) Class I alloantibody is thought to be involved in transfusion-related acute lung injury. Neutrophils contain various biological substances in four groups of granules, including secretory vesicles, azurophilic granules, specific granules and gelatinase granules. To characterize the activation of neutrophils by HLA Class I alloantibody, we investigated whether HLA Class I alloantibody could cause the degranulation of these groups of granules either coordinately or selectively. MATERIALS AND METHODS: Sera containing HLA-A24 alloantibody were incubated with neutrophils in a washed whole blood system. CD11b expression (secretory vesicles) on neutrophils was analysed by flow cytometry, and the secretion of markers of each granule was determined by ELISA. RESULTS: The treatment of cross-matching-positive neutrophils with sera containing HLA-A24 alloantibody caused the significant expression of CD11b, and the significant secretion of neutrophil elastase and myeloperoxidase, azurophilic granule markers and heparin-binding protein (HBP), which is localized in secretory vesicles and azurophilic granules when compared with cross-matching-negative neutrophils. In contrast, no significant differences were observed in the secretion of lactoferrin, a marker of specific granules, and matrix methalloproteinase-9, a marker of gelatinase granules between cross-matching-positive and cross-matching-negative cells upon stimulation with sera. CD11b expression and secretion of HBP by serum was partially inhibited by p38 mitogen-activated protein (MAP)-kinase inhibitors. CONCLUSION: Neutrophils activated with sera containing HLA Class I alloantibody caused the preferential degranulation of azurophilic granules and secretory vesicles. This process was at least in part mediated by p38 MAP kinase-involved signal transduction.

Superagonistic CD28 antibody induces donor-specific tolerance in rat renal allografts.

The ultimate goal of organ transplantation is to establish graft tolerance where CD4+CD25+FOXP3+ regulatory T (Treg) cells play an important role. We examined whether a superagonistic monoclonal antibody specific for CD28 (CD28 SA), which expands Treg cells in vivo, would prevent acute rejection and induce tolerance using our established rat acute renal allograft model (Wistar to Lewis). In the untreated or mouse IgG-treated recipients, graft function significantly deteriorated with marked destruction of renal tissue, and all rats died by 13 days with severe azotemia. In contrast, 90% of recipients treated with CD28 SA survived over 100 days, and 70% survived with well-preserved graft function until graft recovery at 180 days. Analysis by flow cytometry and immunohistochemistry demonstrated that CD28 SA induced marked infiltration of FOXP3+ Treg cells into the allografts. Furthermore, these long-surviving recipients showed donor-specific tolerance, accepting secondary (donor-matched) Wistar cardiac allografts, but acutely rejecting third-party BN allografts. We further demonstrated that adoptive transfer of CD4+CD25+ Treg cells, purified from CD28 SA-treated Lewis rats, significantly prolonged allograft survival and succeeded in inducing donor-specific tolerance. In conclusion, CD28 SA treatment successfully induces donor-specific tolerance with the involvement of Treg cells, and thus the therapeutic value of this approach warrants further investigation and preclinical studies.

Unrelated cord blood transplantation in CML: Japan Cord Blood Bank Network analysis.

We analysed 86 patients with CML who received unrelated cord blood transplantation (UCBT), identified through a registry of the Japan Cord Blood Bank Network. At transplantation, the median patient age was 39 years (range, 1-67 years); 38 patients were in chronic phase (CP), 13 in the accelerated phase (AP) and 35 in blast crisis (BC). Median duration from diagnosis to UCBT was 1.5 years (range, 0.2-14.6 years). A nucleated cell (NC) dose of more than 3.0 x 10(7) per kg was sufficient to achieve neutrophil (91%) and platelet recovery (86%), whereas the lower dose of NC achieved only 60 and 61%, respectively. The duration and type of pre-transplant treatment did not affect neutrophil or platelet recovery. Results of multivariate analysis indicated that older patients (>50 years) had a higher incidence of transplant-related mortality. Advanced-disease stage and lower doses of NCs were significantly associated with lower leukaemia-free and event-free survival. At 2-year survival for patients in CP, AP and BC was 71, 59 and 32%, respectively (P=0.0004). A pre-transplant European Group for Blood and Marrow Transplantation scoring system was effective in predicting the outcome of UCBT. We conclude that UCBT is a reasonable alternative therapy for patients with CML.

Application of Perfusate With Human-Derived Oxygen Carrier Solution Under Subnormothermic Machine Perfusion for Donation After Cardiac Death Liver Grafts in Pigs.

Oxygenation is necessary for aerobic metabolism, which maintains adenosine triphosphate within the graft organ. In recent years, some studies have demonstrated that subnormothermic machine perfusion (SNMP) with hemoglobin-based oxygen carriers has the potential to improve oxygen metabolism. OBJECTIVE: The aim of this study was to evaluate the effectiveness of perfusate with human-derived hemoglobin vesicles (HbV) under SNMP in a pig model of donation after cardiac death. MATERIALS AND METHODS: In this study, pig livers were procured with a warm ischemic time of 60 minutes and were preserved in 3 groups for 240 minutes. The preservation conditions were as follows: 4°C cold storage (Group 1); SNMP with University of Wisconsin perfusate alone (Group 2); and SNMP (21°C) with University of Wisconsin solution and HbV (hemoglobin, 0.6 mg/dL) perfusate (Group 3). All livers were perfused for 120 minutes using pig autologous blood machine perfusion (reperfusion phase). We investigated the aspartate transaminase level and hemodynamics (portal vein resistance and oxygen consumption) in the preservation and reperfusion phases. A histologic study (hematoxylin-eosin staining) was performed after 240 minutes of preservation. RESULTS: The portal vein resistance of Group 3 was not increased in comparison with Group 2. During preservation, the oxygen consumption of Group 3 was higher than that of Group 2. However, the level of aspartate transaminase did not differ between Groups 2 and 3. CONCLUSION: The present study revealed that perfusate with HbV increased the oxygen consumption of the donor liver during SNMP.

Safety of Elderly Living Kidney Donors: 2 Cases of Donors Older Than 80 Years: A Case Report.

Much controversy exists over the performance of elderly living donor kidney transplantation. We report the safety of 2 cases of elderly living kidney donations in our hospital. CASE 1: An 82-year-old man was a living kidney donor for his 56-year-old son. The donor suffered from hypertension, but has successfully managed his blood pressure with only one medication. His serum creatinine was 0.7 mg/dL and inulin clearance was 122.5 mL/min, which met the usual criteria for living kidney donors. This was his son's secondary kidney transplantation, and no other donors existed. CASE 2: An 80-year-old woman was a living kidney donor for her 45-year-old son. Her serum creatinine was 0.61 mg/dL and inulin clearance was 71.7 mL/min, which met the marginal kidney donor criteria. In both cases, we determined that the donor kidney function was acceptable. Though we explained the risks of the transplantation thoroughly, the patients' strong will to offer a kidney to their family member did not change. We decided to carry out the transplantation. At the time of publication, nearly 2 years have passed since the transplantation, but both donors and recipients are doing well. In the future, it seems more likely that the number of elderly living donor kidney transplantation will rise. On one hand, there is no absolute contraindication for elderly donors, while on the other hand, the criteria for a living kidney donor must be strictly examined. Furthermore, careful observation of both donors and recipients after transplantation is required.

Dual Gas Treatment With Hydrogen and Carbon Monoxide Attenuates Oxidative Stress and Protects From Renal Ischemia-Reperfusion Injury.

BACKGROUND: Hydrogen (H2) and carbon monoxide (CO) gas are both reported to reduce reactive oxygen species and alleviate tissue ischemia-reperfusion (I-R) injury. The present study was conducted to evaluate the effects of a mixture of H2 gas and CO gas (dual gas) in comparison with hydrogen gas (H2: 2%) alone on I-R renal injury (composition of dual gas; N2: 77.8%; O2: 20.9%; H2: 1.30%; CO: 250 parts per million). METHODS: Adult male Sprague-Dawley rats (body weight 250-280 g) were divided into 5 groups: (1) sham operation control, (2) dual gas inhalation (dual treatment) without I-R treatment, (3) I-R renal injury, (4) H2 gas alone inhalation (H2 treatment) with I-R renal injury, and (5) dual treatment with I-R renal injury. I-R renal injury was induced by clamping the left renal artery and vein for 45 minutes followed by reperfusion, and then contralateral nephrectomy was performed 2 weeks later. Renal function was markedly decreased at 24 hours after reperfusion, and thereafter the effects of dual gas were assessed by histologic examination and determination of the superoxide radical, together with functional and molecular analyses. RESULTS: Pathologic examination of the kidney of I-R rats revealed severe renal damage. Importantly, cytoprotective effects of the dual treatment in comparison with H2 treatment and I-R renal injury were observed in terms of superoxide radical scavenging activity and histochemical features. Rats given dual treatment and I-R renal injury showed significant decreases in blood urea nitrogen. Increased expression of several inflammatory cytokines (tumor necrosis factor-α, interleukin-6, intracellular adhesion molecule-1, nuclear factor-κB, hypoxia inducible factor-1α, and heme oxygenase-1) was attenuated by the dual treatment. CONCLUSIONS: Dual gas inhalation decreases oxidative stress and markedly improves I-R-induced renal injury.

Effect of Systematic Conversion to Generic Mycophenolate Mofetil (MMF) in Kidney Transplantation: A Single-Center Clinical Experience from Japan.

INTRODUCTION: Recently, more and more generic drugs have been used for immunosuppressive drugs in the field of organ transplantation. Some reports have indicated that blood concentration of most generic drugs is difficult to maintain stability, and it may cause the difference in graft survival of transplanted organs between original drugs and generic drugs. In this article, we report the cases could not maintain blood concentration of generic drugs of mycophenolate mofetil (MMF). RESULTS: In 4 cases out of 5 cases that we had to change original MMF to generic MMF, there were cases that blood concentration level was not stabilized. There were possibility that the lowered blood concentration level of MMF caused a rejection, in two cases. Mean MMF trough level was decreased from 3.6 ± 1.9 µg/mL to 0.6 ± 0.4 µg/mL. Due to the early detection, it did not become severe or failure of graft function, however, we cannot deny the possibilities that side effects were increased and rejection rose. In these cases, we discontinued to use the generic drugs thereafter due to unstable plasma concentration of MMF. DISCUSSION: Some reports have indicated that failure to maintain plasma concentration of MMF leads to rejection. Therefore, maintenance of effective plasma concentration and prevention of rejection are essential to long-term graft survival in kidney transplant. CONCLUSION: Generic drug formulations may exhibit differences in effects and absorption compared to the brand-name drug. If the generic drug should be used, patients should be closely monitored.

Late blockade of T cell costimulation interrupts progression of experimental chronic allograft rejection.

Early blockade of T cell-costimulatory activation pathways prevents development of experimental chronic allograft rejection. Ongoing T cell recognition of alloantigen and activation may also play an important role in progression of chronic rejection, but definitive evidence is lacking. We used the fusion protein CTLA4Ig to block CD28-B7 T cell costimulation late after the onset of initial graft injury. Using the F334 into LEW rat model of chronic renal allograft rejection, transplant recipients were treated with a 10-d course of cyclosporine, and a subgroup received a single injection of CTLA4Ig at 8 wk after transplant. Functionally, CTLA4Ig administration prevented development of progressive proteinuria (14.3+/-4.1 mg/24 h versus 41.0+/-12.0 mg/24 h at 24 wk after transplant, P < 0.05). Histologically, graft mononuclear cell infiltration, glomerular hypertrophy, focal and segmental glomerulosclerosis, and intimal vascular hyperplasia were all attenuated in CTLA4Ig-treated animals. Lastly, reverse transcriptase-PCR and immunohistologic studies showed a significant reduction in the intragraft expression of key products of T cell and macrophage activation, and upregulation of what have recently been termed as "protective" genes, including the bcl family members, Bcl-2 and Bcl-xL, and hemoxygenase. Our data are the first to demonstrate that blocking T cell-costimulatory activation late after transplantation, after initial graft injury, prevents progression of chronic allograft rejection supporting the hypothesis that ongoing T cell recognition of alloantigen and activation are key mediators of ongoing chronic allograft rejection.

Nephron supply is a major determinant of long-term renal allograft outcome in rats.

The effects of augmenting the nephron supply on indices of allograft injury were assessed in a rat model of "chronic rejection." Orthotopic renal allotransplantation into unine-phrectomized rats was followed by excision (allograft-alone group) or preservation of the remaining native kidney (allograft+native kidney group) such that the total kidney complement was either the allograft alone, or the allograft plus one retained native kidney. After 18 wk, values for GFR (1.85 +/- 0.3 ml/min) and kidney weights (2.3 +/- 0.2 g) in allograft-alone rats were far in excess of corresponding values in the allograft of allograft+native kidney rats (0.88 +/- 0.1 ml/min and 1.1 +/- 0.5 g, respectively). Proteinuria (35 +/- 2 mg/d) and allograft glomerulosclerosis (24 +/- 8%) also characterized allograft-alone but not allograft+native kidney rats, in whom glomerular structure (allograft glomerulosclerosis, 4 +/- 1%; native kidney glomerulosclerosis, 0%) and glomerular functional integrity (proteinuria 7 +/- 0.7 mg/d) were well preserved. Thus, the observed allograft protection derived from the presence of a retained recipient native kidney supports the hypothesis that a single renal allograft contains insufficient nephrons to prevent progressive renal injury, implicating nephron supply as a major determinant of long-term allograft outcome.

Chronic graft rejection.

Although chronic rejection remains the most crucial cause of organ graft loss over the long term, its etiology is not well defined. Early injury to graft endothelial cells caused by alloantigen-independent factors, such as ischemia or reperfusion, as well as alloantigen-dependent events, such as acute rejection, have been implicated. Macrophages and their products, peptide growth factors and adhesion molecules are all thought to play an important role in this process via the cytokine-adhesion molecule cascade. Although new immunosuppressive agents, including RS61443 or rapamycin, may be effective in preventing antigen-driven components of this condition, risk factors for initial non-immune injury must also be considered and, if possible, countered.

Identification of arginase in human placental villi.

l-Arginine is the common substrate for arginase and nitric oxide synthase (NOS). Arginase converts l-arginine to urea and ornithine, which is the principal precursor for production of polyamines required for cell proliferation. Human placenta expresses endothelial NOS (eNOS) in syncytiotrophoblasts, but the expression of arginase has not been fully elucidated. Our aim was to investigate the expression and distribution patterns of arginase-I (A-I) and arginase-II (A-II) in human placental villi in the first trimester and at term using immunohistochemistry, RT-PCR and Western blot analysis. The arginase enzyme activity in placental villi was also measured. Immunohistochemistry showed different distribution patterns of the arginase isoforms during gestation: A-I was observed only in cytotrophoblasts, while A-II was observed in both cytotrophoblasts and syncytiotrophoblasts. RT-PCR and Western blot analysis showed expression of A-I and A-II in the first trimester and at term in human placental villi. Expression of A-II and arginase activity was greater in the first trimester than at term. Differentiation of cytotrophoblasts into syncytiotrophoblasts may be associated with l-arginine metabolism through modulation of l-arginine availability for eNOS and A-I. And elevated arginase activity in the early gestational period may be responsible for proliferation of trophoblasts by increasing polyamines production. These results suggest that the l-arginine-ornithine-polyamine and l-arginine-nitric oxide pathways play a role in placental growth and development.