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Biomedical subjects

R E Clark

Publications and source records attributed to R E Clark.

At least 19 recordsLinked to original sources
PubMed2006

A survey of tractors and rollover protective structures in Washington State.

A survey of farms in Washington State was conducted to determine tractor characteristics and the presence of rollover protective structures (ROPS) in a state with more inclusive rules on tractor retrofitting than federal regulations. A total of 544 valid surveys were completed from a proportional random sample across different types of farms. Responders indicated that 58% of tractors overall were equipped with ROPS, and 42% of the tractors without ROPS were exempt from the state rules. Seatbelts on tractors equipped with ROPS were reportedly used "sometimes" or more 30% of the time, and 17% of these tractors had no seatbelt installed. Tractors used for row crop farming were significantly more likely to be equipped with ROPS than those used for tree, vine, or hops farming. Older tractors were used for fewer hours, were less likely to be ROPS-equipped, and were less likely to be operated while wearing a seatbelt. The results were consistent with a positive effect of the Washington State ROPS requirements, demonstrated by the increased percentage of ROPS-equipped pre-1976 tractors, as compared to other states, and by the difference between ROPS-equipped tractors in exempt and non-exempt types of farming. The results point to the need for prevention activities to increase seatbelt use on ROPS-equipped tractors, and for further development of practical protection for tractors operating under overhead obstacles.

Accidents, Occupational↗
PubMed2005

Management of chronic myeloid leukaemia in relapse following donor lymphocyte infusion induced remission: a retrospective study of the Clinical Trials Committee of the British Society of Blood & Marrow Transplantation (BSBMT).

Donor lymphocyte infusion (DLI) can restore remission in a high percentage of patients with chronic myeloid leukaemia (CML) who relapse after allogeneic stem cell transplant (SCT). Subsequent relapses after a DLI-induced remission do occur and the optimal management of these patients is not defined. A retrospective study of the practice of UK transplant centres was conducted. In all, 13 patients from seven centres were identified: all were treated for relapse post allogeneic SCT with DLI and achieved either a complete cytogenetic (n=5) or molecular (n=8) remission. All patients subsequently had a second relapse, at molecular (n=7), cytogenetic (n=4) and haematological (n=2) levels. Further DLI was used in the treatment of 11 patients, imatinib mesylate in three and chemotherapy in two. The two patients with haematological relapse died of blastic disease. The remaining 11 patients achieved either a complete cytogenetic (n=2) or molecular (n=9) remission. Nine patients remain in molecular remission at a median follow-up of 29 months, seven of whom had received DLI alone as treatment for second relapse, one DLI plus imatinib and one imatinib alone. Toxicity following DLI for second relapse was low. Longer follow-up will be required to see if these second DLI-induced remissions will be durable.

Adult↗
PubMed2004

A randomized study (WOS MM1) comparing the oral regime Z-Dex (idarubicin and dexamethasone) with vincristine, adriamycin and dexamethasone as induction therapy for newly diagnosed patients with multiple myeloma.

Whilst infusional vincristine, adriamycin and dexamethasone (VAD) is an effective treatment for patients with multiple myeloma (MM), administration may be complicated by line-associated infections and thromboses. The oral regime, Z-Dex (idarubicin and dexamethasone) has been shown to be efficacious in MM. We conducted a randomized study comparing Z-Dex with VAD as induction therapy in newly diagnosed MM patients. A total of 106 patients (median age, 56 years; range: 37-73; Durie-Salmon stage II/III) were randomized to receive four to six cycles of Z-Dex or VAD. Central line complications were reported in 38 patients on 57 cycles, primarily because of infection. Neutropenia (all grades) was more common in the Z-Dex arm (P = 0.009) although grade III/IV neutropenia was not significantly different between the treatment groups (P = 0.06). Infections (all grades) were more commonly seen in the VAD arm (P = 0.001) although grade III/IV infections were not significantly different between the two groups (P = 0.081). The responses to therapy (complete/partial response) in evaluable patients were: VAD 74% vs. Z-Dex 58%, with an estimated difference in response of 16% (95% CI -2-33, P = 0.075). VAD recipients (15%) suffered early treatment-related mortality compared with 12% of Z-Dex recipients. Overall, 45 patients have died: disease progression (Z-Dex n = 13, VAD n = 10), regimen-related toxicity (Z-Dex n = 2, VAD n = 2), infection (Z-Dex n = 0, VAD n = 3), other causes (Z-Dex n = 7, VAD n = 2), unknown (Z-Dex n = 3, VAD n = 2). This study demonstrated that Z-Dex might be a suitable oral alternative to VAD for treating newly diagnosed MM patients, although definitive evidence for equivalence is not provided.

Adult↗
PubMed2003

A prospective, randomized trial for the prevention of mucositis in patients undergoing hematopoietic stem cell transplantation.

Oral mucositis is a complication common to many cancer therapies and produces considerable pain and morbidity. The present study reports a double-blind, prospective, randomized clinical trial testing the efficacy of a calcium phosphate mouth rinse (Caphosol) with fluoride treatments vs a standard regimen of fluoride rinsing and placebo tray treatments in 95 patients undergoing hematopoietic stem cell transplantation (HSCT). The days and severity of mucositis were prospectively evaluated. There were statistically significant decreases in days of mucositis (3.72 vs 7.22 P=0.001), duration of pain (2.86 vs 7.67, P=0.0001), dose of morphine (34.54 mg vs 122.78 mg), days of morphine (1.26 vs 4.02, P=0.0001) and days to the onset of engraftment ANC (absolute neurotrophil count)>200 mm(3) (11.12 vs 12.56) in the Caphosol and fluoride treatment group vs fluoride-rinse group, respectively. Caphosol, a neutral, supersaturated, Ca(2+)/PO(4)(3-) mouth rinse, used in combination with topical fluoride treatments, is superior to fluoride rinse alone in reducing the frequency, intensity and duration of oral mucositis in patients undergoing HSCT.

Analysis of Variance↗
PubMed2003

Autografting as a risk factor for persisting iron overload in long-term survivors of acute myeloid leukaemia.

We studied the iron status of 32 evaluable adult acute myeloid leukaemia (AML) survivors who were entered into the UK Medical Research Council acute myeloid leukaemia (AML) 10 and 12 trials at our institution between 1988 and 1998. Patients were required to have been independent of all blood products for at least 3 years. As a group, the median first serum ferritin level was 1323 mug/l (NR 19-300 mug/l) at a median of 1321 days from the last transfusion confirming the presence of significant iron overload persisting for some years after completion of all therapy and blood products. There was a general trend for the serum ferritin level to fall with time, but the fall was less pronounced in men and carriers of the C282Y mutation. Recipients of autologous stem cell transplantation (SCT) had a higher median first serum ferritin level (3245 mug/l) than patients who received chemotherapy alone (1148 mug/l) or allogeneic SCT (1334 mug/l) because of increased use of transfused blood. Nine of the 10 recipients of autologous SCT underwent venesection. No evidence of end organ damage was seen in any patient. Serial monitoring of serum ferritin and assessment of the C282Y status may be useful in all long-term AML survivors, especially autograft recipients.

Acute Disease↗
PubMed2003

Response to imatinib in patients who relapse after allogeneic stem cell transplantation for chronic myeloid leukemia.

We studied 128 patients with chronic myeloid leukemia (CML) relapsing after allogeneic stem cell transplantation (SCT). Disease at the time of treatment with Imatinib was in chronic phase (CP) in 51 patients, accelerated phase (AP) in 31 and blastic crisis (BC) in 46. Of the 51 patients in CP, 14 were in cytogenetic and two in molecular relapses. The median interval between relapse and Imatinib therapy was 5 months (0-65). A total of 50 patients had failed treatment with donor lymphocyte infusions prior to Imatinib. The overall hemato-logical response rate was 84% (98% for patients relapsing in CP). The complete cytogenetic response (CCR) was 58% for patients in CP, 48% for AP and 22% for patients in BC. Complete molecular responses were obtained in 25 patients (26%), of whom 21 were in CP or AP. With a median follow-up of 9 months, the estimated 2-year survival for CP, AP and BC patients was 100, 86 and 12%, respectively. Out of 79 evaluable patients, 45 (57%) achieved full donor and 11 (14%) mixed chimerism after Imatinib. We conclude that Imatinib has significant activity against CML in relapse after allogeneic SCT. Durable cytogenetic and molecular remissions are obtainable in patients in CP.

Adult↗
PubMed2002

Chronic lymphocytic leukaemia developing in the course of chronic myeloid leukaemia.

Both chronic myeloid leukaemia (CML) and chronic lymphocytic leukaemia (CLL) are rare illnesses. Their co-existence has been previously reported, typically with CML following CLL. We report to our knowledge the first case of CLL developing some years after initial diagnosis of Philadelphia (Ph) chromosome positive CML. We provide molecular evidence that CLL arose in a Ph negative clone. The implications of the findings are discussed.

Benzamides↗
PubMed2001

Expression of c-myc is not critical for cell proliferation in established human leukemia lines.

BACKGROUND: A study was undertaken to resolve preliminary conflicting results on the proliferation of leukemia cells observed with different c-myc antisense oligonucleotides. RESULTS: RNase H-active, chimeric methylphosphonodiester / phosphodiester antisense oligodeoxynucleotides targeting bases 1147-1166 of c-myc mRNA downregulated c-Myc protein and induced apoptosis and cell cycle arrest respectively in cultures of MOLT-4 and KYO1 human leukemia cells. In contrast, an RNase H-inactive, morpholino antisense oligonucleotide analogue 28-mer, simultaneously targeting the exon 2 splice acceptor site and initiation codon, reduced c-Myc protein to barely detectable levels but did not affect cell proliferation in these or other leukemia lines. The RNase H-active oligodeoxynucleotide 20-mers contained the phosphodiester linked motif CGTTG, which as an apoptosis inducing CpG oligodeoxynucleotide 5-mer of sequence type CGNNN (N = A, G, C, or T) had potent activity against MOLT-4 cells. The 5-mer mimicked the antiproliferative effects of the 20-mer in the absence of any antisense activity against c-myc mRNA, while the latter still reduced expression of c-myc in a subline of MOLT-4 cells that had been selected for resistance to CGTTA, but in this case the oligodeoxynucleotide failed to induce apoptosis or cell cycle arrest. CONCLUSIONS: We conclude that the biological activity of the chimeric c-myc antisense 20-mers resulted from a non-antisense mechanism related to the CGTTG motif contained within the sequence, and not through downregulation of c-myc. Although the oncogene may have been implicated in the etiology of the original leukemias, expression of c-myc is apparently no longer required to sustain continuous cell proliferation in these culture lines.

Journal Article↗
PubMed2001

Direct evidence that leukemic cells present HLA-associated immunogenic peptides derived from the BCR-ABL b3a2 fusion protein.

The BCR-ABL oncogene is central in the pathogenesis of chronic myeloid leukemia (CML). Here, tandem nanospray mass spectrometry was used to demonstrate cell surface HLA-associated expression of the BCR-ABL peptide KQSSKALQR on class I-negative CML cells transfected with HLA-A*0301, and on primary CML cells from HLA-A3-positive patients. These patients mounted a cytotoxic T-lymphocyte response to KQSSKALQR that also killed autologous CML cells, and tetramer staining demonstrated the presence of circulating KQSSKALQR-specific T cells. The findings are the first demonstration that CML cells express HLA-associated leukemia-specific immunogenic peptides and provide a sound basis for immunization studies against BCR-ABL.

Adult↗
PubMed2001

Attempts to improve treatment outcomes in acute myeloid leukemia (AML) in older patients: the results of the United Kingdom Medical Research Council AML11 trial.

In an attempt to improve induction chemotherapy for older patients with acute myeloid leukemia (AML),1314 patients were randomized to 1 of 3 induction treatments for 2 courses of DAT (daunorubicin, cytarabine, and thioguanine) 3 + 10, ADE (daunorubicin, cytarabine, and etoposide) 10 + 3 + 5, or MAC (mitoxantrone-cytarabine). The remission rate in the DAT arm was significantly better than ADE (62% vs 50%; P =.002) or MAC (62% vs 55%; P =.04). This benefit was seen in patients younger and older than 70 years. There were no differences between the induction schedules with respect to overall survival at 5 years (12% vs 8% vs 10%). A total of 226 patients were randomized to receive granulocyte colony-stimulating factor (G-CSF) or placebo as supportive care from day 8 after the end of treatment course 1. The remission rate or survival were not improved by G-CSF, although the median number of days to recover neutrophils to 1.0 x 10(9)/L was reduced by 5 days. Patients who entered remission (n = 371) were randomized to stop after a third course (DAT 2 + 7) or after 6 courses, ie, a subsequent COAP (cyclophosphamide, vincristine, cytarabine, and prednisolone), DAT 2 + 5, and COAP. The relapse risk (81% vs 73%), disease-free survival (16% vs 23%), and overall survival at 5 years (23% vs 22%) did not differ between the 3-course or 6-course arms. In addition to a treatment duration randomization, 362 patients were randomized to receive 12-month maintenance treatment with low-dose interferon, but no benefit was seen with respect to relapse risk, disease-free survival, or overall survival.

Age Factors↗
PubMed2001

Retrograde amnesia.

In humans, the phenomenon of temporally graded retrograde amnesia has been described in the clinic and the laboratory for more than 100 years. In the 1990s, retrograde amnesia began to be studied prospectively in experimental animals. We identified 13 published studies in which animals were given equivalent training at two or more separate times before damage to the fornix or hippocampal formation. Eleven of these studies found temporally graded retrograde amnesia, with the extent of amnesia ranging from several days to a month or two. We consider these studies and also suggest why temporally graded retrograde amnesia has sometimes not been observed. Although the evidence in favor of temporally graded retrograde amnesia is substantial, the inference from this work, that memory is reorganized as time passes, is rather vague and depends on mechanisms yet to be identified. It is therefore encouraging that many opportunities exist for moving beyond purely descriptive studies to studies that involve treatments or manipulations directed toward yielding information about mechanisms.

Amnesia, Retrograde↗
PubMed2001

Rats with lesions of the hippocampus are impaired on the delayed nonmatching-to-sample task.

Rats with ibotenic acid lesions of the hippocampus (H-IBO) were trained on the trial-unique delayed nonmatching-to-sample task (DNMS) using a short delay of 4 s. The H-IBO group learned the nonmatching rule as quickly as control animals. However, performance was impaired on the DNMS task when the delay between the sample and choice phase was increased to 1 or 2 min. The use of 4-s delay (probe) trials indicated that the H-IBO animals retained the nonmatching-to-sample rule throughout testing. In a second experiment, using the same groups of rats, extended training at the 1-min delay did not ameliorate the deficit produced by H-IBO lesions. The finding of impaired recognition memory in rats after hippocampal lesions is consistent with findings from humans and monkeys. Several methodological issues are considered that have complicated the interpretation of earlier studies of recognition memory in rats following hippocampal lesions. The capacity for recognition memory in humans, monkeys, and rodents is discussed as a straightforward example of hippocampus-dependent (declarative) memory.

Animals↗
PubMed2001

High frequency of positive surveillance for cytomegalovirus (CMV) by PCR in allograft recipients at low risk of CMV.

Cytomegalovirus (CMV) causes significant morbidity and mortality following allogeneic haemopoietic stem cell transplantation. A pre-emptive strategy for ganciclovir therapy is widely used, where treatment is commenced on finding positive evidence of CMV replication. Surveillance by PCR has increased the sensitivity for CMV detection, but it is not known whether this may detect cases with evidence of CMV DNAemia who have a low probability of CMV disease. We reviewed our experience of CMV infection and disease since introducing CMV surveillance by PCR. All 30 allografts received bedside leucodepleted CMV-negative blood products. Seven of 10 CMV-positive recipients of a CMV-positive graft developed CMV DNAemia, with three developing clinical disease requiring ganciclovir treatment. In contrast, of 11 low risk patients (CMV-negative recipients of CMV-negative grafts), six developed evidence of CMV DNAemia although only one had clinical evidence of CMV disease requiring ganciclovir. Transfusion records confirmed that four of these had received exclusively CMV-negative blood products. The aetiology of the CMV DNAemia in these cases is unclear. It is suggested that before commencing ganciclovir therapy, confirmatory CMV antigenaemia testing is carried out on samples which test positive for CMV DNA, unless there is high clinical suspicion of CMV disease.

Adolescent↗
PubMed2001

HLA-A3 increases and HLA-DR1 decreases the risk of acute graft-versus-host disease after HLA-matched sibling bone marrow transplantation for chronic myelogenous leukaemia.

Frequencies of human leucocyte antigens (HLA)-A, -B and -DR were determined in 751 patients with chronic myelogenous leukaemia (CML) reported to the European Group for Blood and Marrow Transplantation after bone marrow transplantation from HLA-identical family donors and related to the occurrence of graft-versus-host disease (GVHD). HLA-A3 and DR1 were significantly associated with acute GVHD, the first with a higher risk (44% in HLA-A3(+) versus 34% in HLA-A3(-) patients) and the latter with a lower risk (28% in HLA-DR1(+) versus 38% in HLA-DR1(-) patients) for developing acute GVHD grade II--IV. Both factors were independent of known variables for GVHD as shown in a multivariate analysis. The results show that MHC alleles independently influence the incidence of GVHD in bone marrow transplantation from an HLA-identical donor for first chronic-phase CML. Possible mechanisms might include an HLA antigen-specific allele-associated effect, and/or non-specific allele-associated immune hypo- or hyper-responsiveness.

Adolescent↗