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M Rizeq

Publications and source records attributed to M Rizeq.

7 recordsLinked to original sources
PubMed2001

Donor IFN-gamma receptors are critical for acute CD4(+) T cell-mediated cardiac allograft rejection.

Recent studies using mouse models demonstrate that CD4(+) T cells are sufficient to mediate acute cardiac allograft rejection in the absence of CD8(+) T cells and B cells. However, the mechanistic basis of CD4-mediated rejection is unclear. One potential mechanism of CD4-mediated rejection is via elaboration of proinflammatory cytokines such as IFN-gamma. To determine whether IFN-gamma is a critical cytokine in CD4-mediated acute cardiac allograft rejection, we studied whether the expression of IFN-gamma receptors on the donor heart was required for CD4-mediated rejection. To investigate this possibility, purified CD4(+) T cells were transferred into immune-deficient mice bearing heterotopic cardiac allografts from IFN-gamma receptor-deficient (GRKO) donors. While CD4(+) T cells triggered acute rejection of wild-type heart allografts, they failed to trigger rejection of GRKO heart allografts. The impairment in CD4-mediated rejection of GRKO hearts appeared to primarily involve the efferent phase of the immune response. This conclusion was based on the findings that GRKO stimulator cells provoked normal CD4 proliferation in vitro and that intentional in vivo challenge of CD4 cells with wild-type donor APC or the adoptive transfer of in vitro primed CD4 T cells failed to provoke acute rejection of GRKO allografts. In contrast, unseparated lymph node cells acutely rejected both GRKO and wild-type hearts with similar time courses, illustrating the existence of both IFN-gamma-dependent and IFN-gamma-independent mechanisms of acute allograft rejection.

Animals↗
PubMed2001

Drug absorption may be delayed after stroke: results of the paracetamol absorption test.

BACKGROUND: Autonomic changes are frequent after stroke but it is not known whether gastric emptying is altered. We have investigated this using the paracetamol absorption test. METHODS: 12 acute stroke patients and 13 healthy controls of similar age received 1 g oral paracetamol tablets. We studied all patients within 24 h of the stroke and 5 days later. Standard pharmacokinetic measurements were derived from the plasma paracetamol-time curve. RESULTS: In acute stroke patients, mean plasma T(max) was delayed compared with that in controls (96.3 vs 46.2 min, P=0.015). The C(max) of paracetamol was also lower (16.1 vs 23.9 mg l(-1), P=0.028). The area under the curve of paracetamol did not differ significantly in acute stroke patients and controls. CONCLUSIONS: Gastric emptying appears to be delayed in acute stroke patients, and this may result in delayed pharmacological action of orally administered drugs.

Acetaminophen↗
PubMed2000

CD4 T cell-mediated cardiac allograft rejection requires donor but not host MHC class II.

Numerous studies indicate that CD4 T cells are required for acute cardiac allograft rejection. However, the precise role for CD4 T cells in this response has remained ambiguous owing to the multipotential properties of this T-cell subpopulation. In the current study, we demonstrate the capacity of CD4 T cells to serve as direct effector cells of cardiac allograft rejection. We show that CD4 T cells are both necessary and sufficient for acute graft rejection, as indicated by adoptive transfer experiments in immune-deficient SCID and rag1(-/-) recipients. We have analyzed the contribution of direct (donor MHC class II restricted) and indirect (host MHC class II restricted) antigen recognition in CD4-mediated rejection. Acute CD4 T cell-mediated rejection required MHC class II expression by the allograft, indicating the importance of direct graft recognition. In contrast, reciprocal experiments indicate that CD4 T cells can acutely reject allogeneic cardiac allografts established in rag1(-/-) hosts that were also MHC class II deficient. This latter result indicates that indirect presentation of donor antigens by host MHC class II is not required for acute CD4-mediated rejection. Taken together, these results indicate that CD4 T cells can serve as effector cells for primary acute cardiac allograft rejection, predominantly via direct donor antigen recognition and independent of indirect reactivity.

Acute Disease↗
PubMed1994

Follicular large-cell lymphoma: intermediate or low grade?

PURPOSE: To evaluate the benefit of anthracycline-based chemotherapy, identify prognostic factors, and determine the value of the International Prognostic Factors Index for patients with follicular large-cell (FLC) lymphoma. PATIENTS AND METHODS: This retrospective study includes 96 patients with FLC lymphoma treated at Stanford University Medical Center between 1969 and 1991. Fifty-five patients received doxorubicin plus cyclophosphamide-containing chemotherapy regimens, 21 patients received other chemotherapy regimens, 15 patients received radiotherapy only, and five patients received no initial therapy. Thirty-four patients had stage I or II disease and 62 patients had stage III or IV disease. RESULTS: With a median follow-up duration of 5.2 years (range, 1 to 18), the actuarial 5- and 10-year overall survival rates were 75% and 54%, with actuarial 5- and 10-year freedom from progression (FFP) rates of 53% and 42%, respectively. Patients treated with chemotherapy regimens that contained both doxorubicin and cyclophosphamide had a superior actuarial 10-year FFP rate (55% v 25%, P = .06) and overall survival rate (65% v 42%, P = .04) compared with patients treated with other chemotherapy regimens. Only one patient treated with doxorubicin plus cyclophosphamide relapsed after 3 years. In the multivariate analysis, discordant lymphoma and treatment with chemotherapy regimens not containing both cyclophosphamide and doxorubicin predicted for worse FFP and overall survival rates. In addition, poor performance status and increasing areas of diffuse histology predicted for a worse survival, while anemia and male sex predicted for a worse FFP. The age-specific International Index was useful in predicting outcome; however, few patients with FLC lymphoma had high-risk features. CONCLUSION: The plateau in FFP implies that patients with FLC lymphoma enjoy sustained remissions after standard anthracycline-based chemotherapy. FLC lymphoma should continue to be approached as an intermediate-grade lymphoma with curative intent.

Actuarial Analysis↗
PubMedDate not supplied

Giant cell myocarditis.

BACKGROUND: Giant cell myocarditis is a rare and frequently fatal disorder of unknown origin that is defined histopathologically as diffuse myocardial necrosis with multinucleated giant cells in the absence of sarcoidlike granulomata. The clinical and pathologic features of lymphocytic myocarditis have been described in several recent publications, but the features of idiopathic giant cell myocarditis have not been adequately addressed. METHODS AND RESULTS: We describe five patients with idiopathic giant cell myocarditis who were seen at Stanford University over the past 10 years. In each case the onset was subacute congestive heart failure. After diagnosis each patient received immunosuppressive therapy and was evaluated for heart transplantation. Progressive heart failure and ventricular arrhythmias developed in all. Three died rapidly, two of progressive heart failure and one of sudden cause. Two patients underwent orthotopic heart transplantation and are currently alive, one with disease recurrence. Pathologic studies, including endomyocardial biopsy and evaluation of postmortem or explanted material at transplantation were reviewed. The pathologic studies provided additional support that the giant cells derive from a monocytic/histiocytic lineage. Segmental wall motion abnormalities suggest giant cell myocarditis can be a focal, as well as diffuse process at certain stages of its course. This experience is compared with published cases and implications for diagnosis and treatment are discussed. CONCLUSIONS: In view of the uniformly fatal nature of the disease, heart transplantation should be a serious consideration, and the patients evaluated once the diagnosis is established. Triple-drug immunosuppressive therapy should be considered at the time of diagnosis.

Adult↗