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Ian Thornley

Publications and source records attributed to Ian Thornley.

6 recordsLinked to original sources
PubMed2004

A multiagent strategy to decrease regimen-related toxicity in children undergoing allogeneic hematopoietic stem cell transplantation.

Regimen-related toxicity (RRT) is a frequent cause of morbidity and mortality after allogeneic hematopoietic stem cell transplantation (HSCT). In this pilot study, we examined the feasibility and potential efficacy of administering a fixed combination of agents as a novel approach to reducing RRT in children undergoing HSCT. Thirty-seven patients were treated with ursodeoxycholic acid, folinic acid, vitamin E, and parenteral nutrition titrated to measured energy expenditure in the peritransplantation period. Outcomes were compared with those in historical controls (n = 131). Compliance with oral ursodeoxycholic acid and vitamin E of at least 90% was achieved in a mean of 86% (95% confidence interval, 75%-97%) of patients. In the study group, we observed (1) reduced prevalence and severity of mucositis (P = .008 and.004, respectively); (2) less severe hepatic toxicity (P = .007); and (3) shorter time to engraftment (P = .02) compared with the control group. These benefits appeared most pronounced among high-risk patients. The administration of this regimen, including oral medications, is feasible during the peritransplantation period, and it is well tolerated. The decreased RRT observed in comparison to historical controls suggests that combination approaches deserve exploration as a means of reducing the morbidity of HSCT.

Adolescent↗
PubMed2002

Early hematopoietic reconstitution after clinical stem cell transplantation: evidence for stochastic stem cell behavior and limited acceleration in telomere loss.

Our inability to purify hematopoietic stem cells (HSCs) precludes direct study of many aspects of their behavior in the clinical hematopoietic stem cell transplantation (HSCT) setting. We indirectly assessed stem/progenitor cell behavior in the first year after HSCT by examining changes in neutrophil telomere length, X-inactivation ratios, and cycling of marrow progenitors in 25 fully engrafted allogeneic HSCT recipients. Donors were sampled once and recipients at engraftment and 2 to 6 months and 12 months after HSCT. Telomere length was measured by an in-gel hybridization technique, X-inactivation ratios were measured by the human androgen receptor assay, and cell cycle status was determined by flow cytometric analysis of pyronin Y- and Hoechst 33342-stained CD34(+)CD90(+) and CD34(+)CD90(-) marrow cells. Compared with their donors, recipients' telomeres were shortened at engraftment (-424 base pairs [bp]; P <.0001), 6 months (-495 bp; P =.0001) after HSCT, and 12 months after HSCT (-565 bp; P <.0001). There was no consistent pattern of change in telomere length from 1 to 12 months after HSCT; marked, seemingly random, fluctuations were common. In 11 of 11 informative recipients, donor X-inactivation ratios were faithfully reproduced and maintained. The proportion of CD34(+)CD90(+) progenitors in S/G(2)/M was 4.3% in donors, 15.7% at 2 to 6 months (P <.0001) after HSCT, and 11.5% at 12 months after HSCT (P <.0001, versus donors; P =.04, versus 2-6 months). Cycling of CD34(+) CD90(-) progenitors was largely unchanged. We infer that (1) HSCT-induced accelerated telomere loss is temporary and unlikely to promote graft failure or clonal hematopoietic disorders and (2) the striking fluctuations in telomere length and variation in pattern of telomere loss reflect stochastic determination of HSC fate after HSCT.

Adult↗
PubMed2002

Abnormal telomere shortening in leucocytes of children with Shwachman-Diamond syndrome.

Haemopoietic dysfunction, ranging from single-lineage cytopenia to severe aplasia and/or myelodysplasia (MDS), is prominent in Shwachman-Diamond syndrome (SDS). To assess haemopoietic stem cell proliferation in SDS, we compared leucocyte telomere length in 12 patients with SDS to that of 41 controls, using an in-gel hybridization technique. SDS patients had an age-adjusted mean telomere length 1.4 kilobase pairs (kbp) shorter than controls (P < 0.0001). Patients with'non-severe' SDS (one- or two-lineage cytopenias; no MDS) had shortened telomeres (-1.4 kbp; P = 0.0004), as did those with 'severe' SDS. We conclude that stem cell hyperproliferation is a feature of SDS from its outset.

Adolescent↗
PubMed2002

Telomeres, X-inactivation ratios, and hematopoietic stem cell transplantation in humans: a review.

The marrow repopulating hematopoietic stem cells (HSCs) in an auto- or allograft represent a small fraction of the normal complement of HSCs, yet are required to reconstitute hematopoiesis and sustain it for the lifetime of the recipient. Such a burden imposes a "replicative stress" upon hematopoietic stem/progenitor cells. The finding of accelerated telomere shortening in hematopoietic stem cell transplant (HSCT) recipients raised the specter of accelerated hematopoietic aging. Here, we review the HSCT telomere literature and other studies of surrogate markers of HSC behavior conducted in human HSCT recipients. We present a paradigm for posttransplant hematopoietic reconstitution and speculate on the fate of HSCs in the human transplant setting.

Animals↗
PubMedDate not supplied

Allogeneic bone marrow transplantation in children with chronic myelogenous leukemia.

PURPOSE: To determine the outcome of children undergoing allogeneic bone marrow transplantation for chronic myelogenous leukemia (CML) at the authors' institution. PATIENTS AND METHODS: Between 1985 and 1999, 18 allogeneic bone marrow transplantations were performed in 17 patients with CML at the Hospital for Sick Children in Toronto. Median age at diagnosis was 9.5 years (range 3-17). Fourteen patients had disease in the first chronic phase, one had disease in the second chronic phase, and two had disease in the accelerated phase. Preparative regimens varied, with radiation-based protocols used in eight patients. Thirteen donors were related (11 matched, 2 mismatched); four were unrelated (2 matched, 2 mismatched). Patients received T-cell-replete bone marrow a median of 7.5 months (range 2.2-22) from diagnosis. A median of 3.0 x 10(8)/kg nucleated cells was infused (range 1.6-6.7). Graft-versus-host disease (GVHD) prophylaxis consisted of cyclosporine and methotrexate in 13 children. cyclosporine in three, and methotrexate in one. RESULTS: Primary graft failure occurred in one patient. Grade 2 acute GVHD or more developed in 11 of the 17 children (64%; grade 2 in 4, grade 3 in 7). Chronic GVHD occurred in 6 of the 16 patients at risk (37.5%; 5 extensive, 1 localized). No patient experienced overt or cytogenetic relapse. There were two deaths (12%): one from acute GVHD and cytomegalovirus pneumonia and the other from chronic GVHD. Probability of 5-year event-free survival was 87 +/- 9%. CONCLUSIONS: These results strongly support the practice of allotransplantation in children with CML, even in the setting of advanced disease and histoincompatibility. Efforts should be aimed at reducing the transplantation-related death rate.

Adolescent↗