Masayoshi Umesue

Fractionated dosing of cyclophosphamide for establishing long-lasting skin allograft survival, stable mixed chimerism, and intrathymic clonal deletion in mice primed with allogeneic spleen cells

BACKGROUND Injection of allo-spleen cells (SC) followed by a single dose of cyclophosphamide (CP) can induce tolerance of tumor and/or skin allografts in mice. To minimize the damage caused by CP, fractionation of CP that can establish long-lasting skin graft survival, stable mixed chimerism, and intrathymic clonal deletion in the host was investigated in the present study. METHODS Allo-SC (10(8)) were given intravenously on day 0. CP at 200 mg/kg was given intraperitoneally on day 2 in a single dose (CP 200x1 group). CP at 100, 66, 50, 40, and 33 mg/kg was given daily from day 1 through days 2, 3, 4, 5 and 6, respectively, in the fractionated doses (CP 100x2, 66x3, 50x4, 40x5, and 33x6 groups; total dose=200 mg/kg). Allografting was performed on day 14. RESULTS In a fully allogeneic combination of C57BL/6 (H2b)-->AKR (H2k, Mls-1a), an EL-4 tumor (H2b) was specifically accepted to kill the AKR mice in all of the SC+CP 200x1, 100x2, 66x3, 50x4, 40x5, and 33x6 groups (n=6), but C57BL/6 skin graft survival was not prolonged in any of the tumor-tolerant groups. In an H2-identical combination of AKR-->C3H (H2k, Mls-1b), AKR skin graft survival was prolonged remarkably (80-90 days) in the SC+CP 200x1, 100x2, and 66x3 groups (n=5-11), but was prolonged moderately (20-60 days) in the SC+CP 50x4 and 40x5 groups. In both of the SC+CP 200x1 and 66x3 groups in the AKR-->C3H combination, mixed chimerism was maintained for as long as 100 days after tolerance induction in both the spleen and thymus, associated with intrathymic clonal deletion of Vbeta6+ T cells. The decreases in leukocyte count, hemoglobin level, spleen weight, SC count, and body weight were significantly smaller in the SC+CP 66x3 group than in the SC+CP 200x1 group. CONCLUSIONS Fractionated CP is effective in ameliorating the compromised state induced by a single dose of CP. To induce a long-lasting skin allograft survival associated with stable mixed chimerism and intrathymic clonal deletion in an H2-identical combination, 200 mg/kg of CP can be divided into three or fewer fractions.

Ventricular energetics in endoventricular circular patch plasty for dyskinetic anterior left ventricular aneurysm

BACKGROUND The endoventricular circular patch plasty (Dor procedure) applies to patients with a left ventricular dysfunction due to an ischemic dilated ventricle. In the present study, we analyzed left ventricular energetics in patients who underwent the Dor procedure. METHODS We measured left ventricular contractility (end-systolic elastance; Ees), afterload (effective arterial elastance; Ea), and efficiency (ventriculoarterial coupling; Ea/Ees, and the ratio of stroke work and pressure-volume area; SW/PVA) based on the cardiac catheterization data before and after the Dor procedure in 8 patients with a postinfarction dyskinetic anterior left ventricular aneurysm. Concomitant procedures included coronary artery bypass grafting in all patients, mitral valve repair in one patient, and cryoablation in one patient. End-systolic elastance (Ees) and Ea were approximated as follows: Ees = mean arterial pressure/minimal left ventricular volume, and Ea = maximal left ventricular pressure/(maximal left ventricular volume-minimal left ventricular volume), and thereafter Ea/Ees and SW/PVA were calculated. The left ventricular volume was normalized with the body surface area. RESULTS End-systolic elastance (Ees) increased after the Dor procedure (from 1.15 +/- 0.60 to 1.86 +/- 0.84 mm Hg x m2 x mL(-1), p < 0.01), thus resulting in an improvement in Ea/Ees and SW/PVA (from 2.94 +/- 1.11 to 1.64 +/- 0.49, p < 0.01, and from 0.426 +/- 0.110 to 0.559 +/- 0.082, p < 0.01, respectively), even though Ea did not substantially change (from 2.96 +/- 0.78 to 2.74 +/- 0.55 mm Hg x m2 x mL(-1), p = 0.4). CONCLUSIONS Left ventricular contractility and efficiency improves after the Dor procedure in patients with a dyskinetic anterior left ventricular aneurysm. However, afterload does not change. The use of appropriate afterload-reducing therapy thus plays an especially important role in the management of patients who undergo the Dor procedure.

Donor-specific prolongation of rat skin graft survival induced by rat-donor cells and cyclophosphamide under coadministration of monoclonal antibodies against T cell receptor alpha beta and natural killer cells in mice.

Because of the recent interest in human xenotransplantation, we investigated the possibility of inducing tolerance in a xenogeneic combination using cyclophosphamide (CP). Donor-specific prolongation of xenogeneic Fisher 344 (F344) rat skin graft survival for up to 60 days was induced in C57BL/6 (B6) mice by giving F344 bone marrow cells and spleen cells on day 0, CP on day 2, and monoclonal antibodies against murine TCR-alpha beta and NK1.1 on days--1 and 3. The inoculation of the xenogeneic cells brought accelerated repopulation of TCR-alpha beta+ T cells, even under the administration of anti-TCR-alpha beta mAb. The quick increase of the host TCR-alpha beta+ T cells caused by the xenogeneic cell injection was deeply suppressed by CP. Mixed lymphocyte reaction, CTL activity, and antibody production against donor F344 were profoundly suppressed for 50 days. Mixed xenogeneic chimerism was observed for 1 month after the inoculation of donor cells in the spleen and peripheral blood of the recipient B6 mice, but was never observed in the thymus. Moreover, when irradiated F344 cells were used in place of viable cells, chimerism was never detected and graft survival was only slightly prolonged. Clonal deletion of V beta 5- or V beta 11-bearing murine T cells was not observed on day 50 in the thymus or spleen of the recipient B6 mice. These results suggest that treatment with viable xenogeneic donor cells, CP, and mAbs against T and NK cells can induce a temporary peripheral mixed chimerism and donor-specific prolongation of xenogeneic skin graft survival. The destruction with CP of T and B cells that are xenoreactive and thus proliferating after antigen stimulation, followed by mechanism other than intrathymic clonal deletion, may be the mechanism of the hyporesponsiveness in the present system.

Right-sided infective endocarditis with a ruptured sinus of Valsalva and multiple septic pulmonary emboli in a patient with atopic dermatitis.

We herein report the case of 34-year-old woman with acute tricuspid valve infective endocarditis (IE) associated with a ruptured sinus of Valsalva and multiple septic pulmonary emboli. She had no history of medical problems, except for atopic dermatitis (AD). Blood cultures identified methicillin-sensitive Staphylococcus aureus. Despite the administration of two months of antibiotic therapy, the patient experienced recurrent pulmonary emboli and developed heart failure due to a left-to-right shunt, whereas the area of vegetation did not change in size. She subsequently underwent surgery for shunt closure and tricuspid valve replacement. The AD was thought to be the cause of the patients bacteremia, which consequently resulted in aggressive right-sided IE.

Mitral valve repair by leaflet sliding and annular downsizing in active infective endocarditis.

We repaired a large defect in the posterior mitral leaflet after an extensive removal of infected tissue, using an extended leaflet sliding and annular downsizing with a small prosthetic ring in 2 patients with active endocarditis.

Sensitization of T-cell receptor-αβ+ T cells recovered from long-term T-cell receptor downmodulation

Although the survival of fully allogeneic skin grafts was prominently prolonged by adult thymectomy in anti‐T‐cell receptor‐αβ monoclonal antibody (TCR‐αβ mAb)‐treated mice compared with that of non‐adult thymectomized (ATX) mice, the skin allografts were eventually rejected. In the anti‐TCR‐αβ mAb‐treated ATX mice, as shown in the present study, most of TCR‐αβ+ cells were promptly activated on day 2 and then rapidly disappeared by day 7, but some TCR‐αβ− Thy‐1+ cells remained at that time. These TCR‐αβ− Thy‐1+ cells which have downmodulated their TCR‐αβ expression may be refractory to depletion events by the mAb treatment. Although these downmodulated T cells re‐expressed their TCR‐αβ on day 50, they could not respond to stimuli via TCR such as TCR cross‐linking or alloantigens. However, they recovered the reactivity to donor antigens on day 85. These results indicate that the downmodulated T cells by anti‐TCR‐αβ mAb treatment are long‐lived and re‐express their TCR‐αβ at a late stage to be sensitized to donor antigen, which suggests that additional regimens may be required to get permanent, or very long‐term, graft acceptance.

Anti-CD4 Monoclonal Antibody Reduces the Dose of Cyclophosphamide Required to Induce Tolerance to H-2 Haplotype Identical Skin Allografts in Mice

Abstract Cyclophosphamide (CP)-induced tolerance which consists of a single i.p. injection of 200 mg/kg CP 2 days after priming with 1 × 10 8 donor spleen cells (SC), leads to long-lasting donor-specific skin allograft tolerance in H-2 compatible, multiminor antigen incompatible, murine strain combinations. In this system, the optimal dose of CP has been suggested to be 200 mg/kg, however, such a dose of CP causes strong myelosuppression. In the present study, we therefore attempted to reduce the dose of CP by administering anti-CD4 monoclonal antibody (mAb) before donor cell priming in this toleranceinducing system. When C3H/He (C3H; H-2 k , Mls-1 b ) mice were injected i.p. with 200 ltg anti-CD4 mAb on day -3, 1 × 10 8 AKR/J (AKR; H-2 k , Mls-1 a ) SC plus 3 × 10 7 bone marrow cells (BMC) i.v. on day -2 and then 100 mg/kg CP i.p. on day 0, a long-lasting donor-specific skin allograft tolerance was established; furthermore, the decreases in the number of leukocytes and the concentration of hemoglobin (Hb) in the peripheral blood were all less in the C3H mice treated with this new combined protocol than in the C3H mice injected with 200 mg/kg CP following the previous protocol. In the periphery of these tolerant mice, the number of donor-reactive Vβ6 + CD4 + T cells decreased and mixed chimerism was observed on both days 14 and 80. On the other hand, in the mice injected with AKR SC, BMC plus 100 mg/kg CP without anti-CD4 mAb, the number of Vβ6 + CD4 + T cells decreased on day 14, and then recovered by day 80 when the mixed chimerism disappeared. These results therefore suggest that the combined use of anti-CD4 . mAb with CP can reduce the dose of CP without affecting the efficiency of inducing donor-specific tolerance, probably due to the enhancement of the destruction effect of donor-reactive T cells by CP.

Angiosarcoma Mimicking an Infected Pseudoaneurysm After Graft Replacement

Fig 2. Prare, and only a few cases have been reported [1, 2]. A 78-year-old man had undergone graft replacement with use of a woven Dacron graft for a distal aortic arch aneurysm 16 years earlier. He had experienced a fever of unknown origin that lasted for several months and could not be resolved. Enhanced computed tomography (CT) revealed an abnormal mass containing calcification and contrast medium adjacent to the previously implanted graft (Fig 1, black arrow indicates anastomosis site of left subclavian artery). Clinical findings and CT suggested an infected pseudoaneurysm emerging from the implanted prosthetic graft. The intraoperative findings showed severe adhesion around the abnormal mass, containing small amounts of old thrombi. The distal segment of the old graft was replaced with a rifampicin-soaked Dacron straight graft, around which the omentum was filled up. Eventually, the patient died 2 months after the operation. Autopsy showed a spongelike mass adjacent to the implanted graft (Fig 2, tumor within the dotted line). Pathologic examination revealed that the mass was a primary angiosarcoma.

Infected Thoracic Aortic Aneurysm Caused by Helicobacter cinaedi

The causative organism is not identified in some cases of infected aneurysms, a life-threatening condition. A 68-year-old man presented with chest/back pain and a 1-year history of intermittent fever and fatigue. Computed tomography revealed a thoracic aortic aneurysm. After several negative blood cultures, he was eventually diagnosed with an infected aneurysm caused by Helicobacter cinaedi via gene analysis of an aortic tissue specimen. As H. cinaedi is a low-virulence bacterium, infection with this pathogen should be suspected in cases of aortic aneurysms with unidentified causative organism and a long history of subjective symptoms. Detailed examinations, including polymerase chain reaction, should be conducted in such cases.

Reconstruction of anterior mitral leaflet using autologous pericardial patch combined with posterior leaflet sliding for active infective endocarditis.

We report a case of active infective endocarditis in a young adult, affecting the anterior and posterior leaflets extensively. The patient underwent a mitral valve repair with extended sliding repair on the posterior leaflet and reconstruction using an autologous pericardial patch supported by an artificial chord on the anterior leaflet. Although we finally needed commissure closing for successful repair, we aggressively achieved a repair-oriented strategy using several techniques in a young patient who may have required mitral valve replacement.