Biomedical subjects
P Martin
Publications and source records attributed to P Martin.
Effect of mixed chimerism on graft-versus-host disease, disease recurrence and survival after HLA-identical marrow transplantation for aplastic anemia or chronic myelogenous leukemia.
The association of mixed (donor/host) chimerism with graft-versus-host disease (GVHD), graft rejection, disease recurrence and survival was investigated in 116 patients with aplastic anemia and 197 patients with chronic myelogenous leukemia (CML) transplanted with unmodified marrow from an HLA-identical sibling donor of opposite sex. Patients with aplastic anemia were conditioned with cyclophosphamide (CY), patients with CML were conditioned with a combination of CY and total body irradiation (TBI) or busulfan. Sixty-three of the patients with aplastic anemia (54%) and 100 patients with CML (51%) were categorized as mixed chimeras based on the concurrent presence of donor and host lymphohematopoietic cells 14 days or later after transplantation. The TBI dose used for conditioning was inversely correlated with the development of mixed chimerism (P < 0.0001) among CML patients. No other patient- or transplant-related parameter was identified which contributed significantly to the development of mixed chimerism. The incidence of rejection was higher but not significantly so in patients with aplastic anemia who were mixed chimeras. The incidence of leukemic relapse in patients with CML who were mixed chimeras was increased only if mixed chimerism occurred after day 100 (P = 0.015). The incidence of acute GVHD (grades II-IV) was lower in mixed chimeras than in complete chimeras, but this difference was statistically significant only for patients with aplastic anemia given single-agent GVHD prophylaxis (P = 0.0008). Mixed chimeras in that group also had a better survival than complete chimeras, while no significant difference was observed in patients with aplastic anemia given drug combinations for GVHD prophylaxis. Among patients with CML, both overall survival (P = 0.03) and relapse-free survival (P = 0.04) were significantly superior in mixed than in complete chimeras. Thus, mixed chimerism was frequent among patients with aplastic anemia and with CML and was not uniformly associated with graft failure or leukemic relapse. The interaction between conditioning regimen, GVHD prophylaxis and chimerism are complex. The survival advantage of mixed chimeras is only in part related to a lower incidence of GVHD and other factors are likely to contribute.
Liver transplantation for fulminant hepatic failure in a Jehovah's Witness.
Jehovah's Witness patients who refuse transfusions have generally not been felt to be candidates for liver transplantation owing to the frequent requirement for blood transfusions during liver transplantation. This is the first report to our knowledge of successful emergent liver transplantation without the use of blood or blood products in a Jehovah's Witness. The surgical and anesthetic strategies employed in achieving a successful outcome are discussed.
Influenza vaccinations do work, but only if health care professionals provide them.
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[Portal imaging: the legal point of view].
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A randomized prospective trial of steroid withdrawal after liver transplantation.
The safety of steroid withdrawal in orthotopic liver transplant (OLT) recipients has been studied in a prospective trial with a comparison control group. Sixty-four recipients of ABO-compatible grafts (42 adults, 22 children) were randomized into a steroid withdrawal (SW) group and a control group. Inclusion criteria included survival > one year post-OLT and no rejection > six months after OLT. Exclusion criteria included previous graft loss secondary to rejection, > two episodes of documented rejection, patients transplanted for autoimmune hepatitis, and patients unable to receive azathioprine. Target HPLC cyclosporine levels in both groups were 100-200 ng/ml. Thirty-three patients entered the SW group and 31 the control group at a mean of 3.5 years after OLT; follow-ups were 592 and 527 days, respectively. Two patients in each group developed biopsy-proven rejection. In the SW group one patient rejected at three months, the other at nine months. Both rejection episodes resolved with only reinstitution of oral prednisone. Of the two patients who rejected in the control group (one at 7 months, one at 11 months) one required conversion to tacrolimus and the other intravenous steroids. There were no significant differences between the two groups for prednisone, azathioprine, cyclosporine doses, cyclosporine levels, liver function tests, and white blood cell counts at base line compared with 12 months. Fasting serum cholesterol in the SW group decreased from 194 +/- 44 mg/dl at baseline to 175 +/- 37 mg/dl at one year, whereas in the control group cholesterol rose from 180 +/- 48 mg/dl to 193 +/- 44 mg/dl. In pediatric patients no significant difference in age-adjusted height velocities over one year was seen between the two groups. We concluded that dual therapy with cyclosporine and azathioprine in stable long-term liver allograft recipients is not associated with an increase in rejection incidence. Prednisone withdrawal may be associated with an improvement in lipid profiles.
Electron relaxation in the conduction band of wide-band-gap oxides.
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Relevance of marrow fibrosis in bone marrow transplantation: a retrospective analysis of engraftment.
A retrospective study compared posttransplant engraftment parameters in 203 patients with myelofibrosis (MF) with those in a population of 203 matched controls without MF. There were no significant differences between these groups in the proportions of patients who died without achieving engraftment and in the disease-free survival distributions. Furthermore, comparisons between the two groups of patients reaching the respective endpoints showed no differences in the time distributions for reaching 0.5 or 1.0 x 10(9)/L granulocytes, but the time to platelet transfusion independence was 3 days longer in patients with MF. In further analysis, results for 33 patients with severe MF were compared with those of their respective controls. The proportions of patients with severe MF who died without reaching these engraftment endpoints and the disease-free survival distributions in the two groups were similar. Among patients who reached the respective engraftment endpoints, there was no statistically significant difference in the pace of granulocyte recovery. In patients with severe MF, there was a 7-day delay in the time to reach platelet transfusion independence and a 2-day delay in the time to reach red blood cell independence, but the differences were not statistically significant. The present results do not substantiate concerns raised by earlier studies. MF may delay the time to reach platelet independence by approximately 3 days and may increase platelet transfusion requirements, but no other perturbation of hematopoietic reconstitution was apparent.
Viscous bursting of suspended films.
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Correlation between donor age and the pattern of liver graft recovery after transplantation.
We have observed an increased rate of delayed nonfunction (DNF) of liver grafts procured from older donors. The aim of this study was to correlate donor age and the patterns of graft failure after transplantation. Pattern of liver injury, synthetic function, and graft survival in recipients receiving liver grafts from donor older than age 50 (group I, n = 95) were compared with matched cohort of recipients transplanted with grafts from donors age 20-30 (group III, n = 50). Primary nonfunction (PNF) of the graft was defined as non-recoverable hepatocellular function necessitating emergency retransplantation within 72 hr. DNF was defined as marginal graft function necessitating retransplantation within one month. Recipient characteristics, including age and preoperative UNOS status, were similar between groups. Ischemic/reperfusion injury, reflected by SGOT and SGPT was more severe in older donors. PNF occurred at similar frequencies for all groups (7%). Normal liver function was regained in 76% of recipients in group I, and in 92% in group II. However, cholestatic pattern was observed in recipient of grafts from group I donors. Rapid rise in bilirubin, despite normalization of prothrombin time and liver transaminases, was the hallmark of DNF. DNF resulted in higher retransplantation rate in group I (24% vs. 8% in group II). Donor age did not affect patient survival. Liberalizing criteria for donor selection, and acceptance of older donors is a calculated risk. Over 75% of the recipients will regain normal liver function. However, a higher number of these grafts will exhibit slow recovery after transplantation, and a significant rate of DNF. Recognition of such pattern and early retransplantation should decrease mortality.
Increased T-cell apoptosis and terminal B-cell differentiation induced by inactivation of the Ets-1 proto-oncogene.
The Ets-1 proto-oncogene is a member of a transcription factor family characterized by homology to the v-ets oncogene. In adult mice, Ets-1 is expressed predominantly in lymphoid cells where it has been implicated in regulating transcription of lymphocyte-specific genes. Following T-cell activation, the specific DNA binding activity of Ets-1 is inactivated by transient phosphorylation, suggesting a function in the transition from the resting to activated state. Ets-1 has also been suggested to cooperate with the AP-1 transcription factor complex to mediate cellular growth factor responses. Here we show, by using RAG-2-deficient blastocyst complementation, that Ets-1 deficiency has dramatic, but different, effects on development and function of T- and B-lineage cells. Ets-1-deficient T cells were present in reduced numbers and were highly susceptible to cell death in vitro. In contrast, Ets-1-deficient B cells were present in normal numbers but a large proportion were IgM plasma cells. Our data demonstrate that Ets-1 is essential for maintenance of the normal pool of resting T- and B-lineage cells.
Lack of correlation between the magnitude of preservation injury and the incidence of acute rejection, need for OKT3, and conversion to FK506 in cyclosporine-treated primary liver allograft recipients.
In order to study further whether a relationship exists between the extent of ischemia-preservation-reperfusion injury (IPRI) and acute rejection (AR) events in liver allografts, we retrospectively reviewed 213 consecutive cyclosporine-treated patients who received their first liver allograft between 1/1/93 and 12/31/93. Of these, 178 fulfilled the study inclusion criteria. The extent of IPRI was assessed by the peak value of aspartate aminotransferase (ASTmax) observed within the first 72 hr posttransplant. For the purpose of univariate analysis, categorical classification of recipients was done based upon ASTmax as follows: group 1, ASTmax < 600 IU/L (n = 43); group 2, ASTmax 600-2000 IU/L (n = 86); and group 3, ASTmax > 2000 IU/L (n = 49). For multivariate analysis, stepwise Cox regression was performed with age, ASTmax, and UNOS status as covariates. At a median follow-up of 271 days there were no statistically significant differences between groups with respect to the incidence of a first episode of AR (47%, 55%, 51%, respectively, P = NS), the timing of AR (respective medians, 9, 10, and 10 days, P = NS), or the proportion of patients treated with OKT3 (9%, 20%, 12%, respectively, P = NS) or converted to FK506 (16%, 12%, 10%, P = NS). Cox regression confirmed the lack of an independent association between the extent of IPRI and any of these outcomes. We conclude that in UW-preserved, cyclosporine-treated primary liver allografts, no correlation exists between the extent of IPRI and the incidence, timing, severity, or refractoriness of clinically defined AR events.
A role for FGF-8 in the initiation and maintenance of vertebrate limb bud outgrowth.
BACKGROUND: The outgrowth of the vertebrate limb bud is the result of a reciprocal interaction between the mesenchyme and a specialized region of the ectoderm, the apical ectodermal ridge (AER), which overlies it. Signals emanating from the AER act to maintain the underlying mesenchyme, called the progress zone, in a highly proliferative and undifferentiated state. Removal of the AER results in the cessation of limb bud growth, thus causing limb truncation. The best candidates for this AER-derived signal are members of the fibroblast growth factor (FGF) family, in particular FGF-4, which can maintain limb bud outgrowth following removal of the AER. However, FGF-4 is only expressed after considerable outgrowth has occurred and a well-developed limb bud has formed, and then only in the posterior part of the AER. Likewise, the other FGFs studied to date are not candidates for this activity. RESULTS: We report evidence that a recently identified member of this family, FGF-8, is expressed in the ectoderm of the prospective limb territory prior to morphological outgrowth of the limb bud in both mouse and chick. Thereafter, expression is maintained throughout the AER during limb development. We have produced and purified the FGF-8 protein, and shown that it will substitute for the AER in maintaining limb bud outgrowth in mouse embryos from which the AER has been surgically removed. FGF-8 does not, however, maintain expression of the sonic hedgehog gene. CONCLUSIONS: These results indicate that FGF-8 is an AER-derived mitogen that stimulates limb bud outgrowth. Moreover, our data suggest that FGF-8 may also be an ectodermally derived mitogen that stimulates the onset of limb bud outgrowth (budding) in the absence of a morphological AER, and indicate the possible involvement of FGF-8 in the establishment of the limb field.
Tacrolimus (FK506) alone or in combination with methotrexate or methylprednisolone for the prevention of acute graft-versus-host disease after marrow transplantation from HLA-matched siblings: a single-center study.
The pharmacokinetics, safety, and efficacy in marrow transplantation of FK506-based immunosuppression for graft-versus-host disease (GVHD) prophylaxis was evaluated in an open label pilot study of 18 patients. Patients more than 12 years of age (median, 35 years; range, 15 to 50 years) with advanced hematologic malignancies receiving HLA-matched sibling marrow grafts were randomized to receive FK506 alone, FK506 and methotrexate (MTX), or FK506 and methyl-prednisolone. Of 17 evaluable patients, all had evidence of sustained marrow engraftment. The median time to an absolute neutrophil count of greater than 500/microL was 15 days for patients receiving FK506 alone or FK506 plus methylprednisolone and 23 days for FK506 plus short MTX. Pharmacokinetic studies did not show any significant difference in clearance of FK506 when administered alone or in combination with methylprednisolone or MTX. The mean bioavailability after oral administration in these same three groups was 0.49 +/- 0.1, 0.27 +/- 0.12, and 0.16 +/- 0.08, respectively (P = .003). The decrease in bioavailability may have resulted from an exacerbation of radiation-induced gastroenteritis by MTX. The most significant adverse effect associated with the administration of FK506 was nephrotoxicity, which occurred in 14 of 18 patients (78%). The mean glomerular filtration rate, determined by clearance of (99MTc)DTPA, decreased to 56% (+/- 18%) of the pretransplant baseline level by week 8 (P = .002). Eight of 18 patients (44%) developed grades II-IV acute GVHD, predominantly of the skin and gastrointestinal tract. The actuarial probability of transplant-related mortality during the first 100 days was 24%. The actuarial probability of 1-year disease-free survival was 39%. In conclusion, although bioavailability of FK506 may be affected in patients receiving MTX, this study suggests that FK506 may have a role in the management of patients after allogeneic marrow transplantation.
Hepatitis C genotypes: the key to pathogenicity?
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Transjugular intrahepatic portosystemic shunts: impact on liver transplantation.
This study was designed to evaluate the impact of transjugular intrahepatic portosystemic shunts (TIPS) on liver transplantation. Historically, the complications of portal hypertension have been temporized with sclerotherapy or surgical portosystemic shunts. In patients whose liver disease progressed, liver transplantation has been used as definitive treatment. More recently, TIPS is being used increasingly for the management of the complications of portal hypertension. The impact of this new modality on liver transplantation is evaluated. The records of 135 adult patients undergoing liver transplantation at University of California at Los Angeles between October 1992 and June 1993 were reviewed. Twenty-three patients had received at least one shunt before transplantation. The TIPS procedure complicated the operative course of 5 patients (22%). In 2 patients the TIPS had been placed cephalad, making placement of the suprahepatic vena caval clamp difficult. In 2 other patients, the shunt had been placed caudad, extending in the extrahepatic portal vein. In all 4 of these patients, the intima had been damaged at the area of the subsequent anastomosis. In the fifth patient, the bile duct had been perforated during the placement of the shunt, causing diffuse bile peritonitis, which was sterile, and the transplantation was performed. The average intraoperative blood loss for these 5 patients was 13 U. There was no significant decrease in intraoperative blood loss for all patients with a TIPS when compared with 112 adults who underwent liver transplantation during the same period (11 U v 10.5 U). The TIPS stent did not improve objective intraoperative parameters as compared with liver transplant recipients without TIPS. The indications for TIPS must be carefully weighed against the potential risks of increasing the technical difficulty of the transplantation and jeopardizing the candidacy of some liver transplantation candidates. Liver transplantation is not facilitated by TIPS insertion and therefore should not be used to justify TIPS placement.
Analysis of the tissue movements of embryonic wound healing--DiI studies in the limb bud stage mouse embryo.
The tissue movements of epithelial spreading and mesenchymal contraction play key roles in many aspects of embryonic morphogenesis. One way of studying these movements in a controlled manner is to make an excisional skin wound to an embryo and watch the wound heal. In this paper we report our studies of healing of a simple excisional lesion made to the limb bud stage mouse embryo. The wounded, living embryo is cultured in a roller bottle; under such conditions the wound heals with a highly reproducible time course and is completely closed by 24 hr. During the healing period the environment bathing the wound can be simply manipulated by adding drugs or factors to the culture medium. We have used DiI to label mesenchymal cells exposed at the margin of the initial wound and, by following their fate and measuring the area of mesenchyme remaining exposed at various time points during the healing process, we have quantified both the extent of mesenchymal contraction and the extent of reepithelialisation by movement of epidermis over mesenchyme. We show that the two types of tissue movement contribute almost equally (50:50) to the total wound closure rate. We have gone on to investigate the cell machinery underlying these processes. In adult wounds the epidermis migrates by means of lamellipodial crawling, but we show that reepithelialisation in the embryo is achieved instead by purse-string contraction of a cable of filamentous actin which assembles in the basal layer of cells at the free edge of the epidermis. Addition of cytochalasin D to the culture medium blocks formation of this actin cable and leads to failure of reepithelialisation. Contraction of adult wound connective tissue appears to be driven by conversion of dermal fibroblasts into a specialist smooth muscle-like fibroblast, the myofibroblast. However, using an antibody recognising the alpha-isoform of smooth muscle actin and specific for smooth muscle cells and myofibroblasts, we show that a similar conversion into myofibroblasts does not occur at any stage during the embryonic wound healing process. These observations indicate that both of the tissue movements of embryonic wound healing utilise cell machinery fundamentally different from that driving the analogous tissue movements of adult healing.
A HinfI polymorphism in the 5' flanking region of the human VNTR locus D1S80.
A restriction fragment length polymorphism (RFLP) characterized by the presence (HinfI+) or absence (HinfI-) of a HinfI site has been found in the 5' flanking region of the VNTR locus D1S80. RFLP-allele frequencies were determined from 82 unrelated individuals: HinfI+ = 0.49, HinfI- = 0.51. The RFLP/VNTR haplotype frequencies show an absolute association between the HinfI+ allele and the VNTR allele of 18 repeat units and an extreme association between the HinfI- allele and the VNTR allele of 24 repeat units. The remaining VNTR alleles associate more randomly with the 2 flanking HinfI alleles.