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Biomedical subjects

R Clift

Publications and source records attributed to R Clift.

At least 55 records · Page 3Linked to original sources
PubMed1989

Engraftment and transfusion requirements after allogeneic marrow transplantation for patients with acute non-lymphocytic leukemia in first complete remission.

This retrospective study analysed factors affecting engraftment and transfusion requirements of platelets and red blood cells in 303 patients transplanted for acute non-lymphocytic leukemia in first remission from HLA-identical or one-antigen mismatched donors. Multivariant analysis showed that the most important factors affecting the speed of engraftment were drugs used for graft-versus-host disease (GVHD) prophylaxis, the development of acute GVHD and HLA matching. Factors affecting only granulocyte recovery included patient age and sex. The radiation regimen used for preparing patients affected the time to platelet independence. Patients transplanted in laminar airflow rooms took longer to achieve red cell independence and required more units of red cells and platelets than patients transplanted in regular rooms. In addition, ABO incompatibility affected red cell transfusion requirements while GVHD prophylaxis and acute GVHD influenced both red blood cells and platelet support.

Adult↗
PubMed1988

High-dose cytarabine and total body irradiation with or without cyclophosphamide as a preparative regimen for marrow transplantation for acute leukemia.

Twenty-nine patients were conditioned for allogeneic marrow transplant with cytarabine (ara-C) (3 g/m2 every 12 hours for 12 doses) and total body irradiation (TBI) (200 cGy daily for six days) with or without cyclophosphamide (CY) (60 mg/kg) to determine toxicity and efficacy. Four patients had chronic myelogenous leukemia (CML) in accelerated phase or blast crisis, and 25 patients had acute leukemia, 24 at stages later than first remission. Three patients (10%) had fatal regimen-related toxicity and another 10% experienced severe toxicity in at least one organ system. The addition of CY to the ara-C and TBI regimen was not associated with an increase in the frequency of severe toxicity. Twenty-five of 29 patients engrafted eight to 33 days posttransplant: three died early before engraftment, and one patient failed to engraft. Ten of 29 patients are alive without disease, and the actuarial probability of disease-free survival for the entire group at 3 years is 33%. Three of ten patients with acute nonlymphocytic leukemia (ANL), six of 15 with acute lymphocytic leukemia (ALL), and one of four with CML are alive and disease free 25 to 42 months (median, 30 months) after transplant. High-dose ara-C (HDara-C) and TBI with or without CY can be administered with approximately the same toxicity as CY plus TBI. Phase III studies appear warranted to determine if these newer regimens provide improved results compared with currently used regimens.

Acute Disease↗
PubMed1988

Canine platelet von Willebrand factor: quantification and multimeric analysis.

Washed canine platelets were shown to express a significant level of von Willebrand factor (vWf). Canine platelet vWf differed from canine plasma vWf by the absence of satellite bands associated with each multimer when resolved by SDS-agarose gel electrophoresis. Expression and multimeric composition of canine platelet vWf was quite similar to that of human platelet vWf. Quantification in both lysed, washed canine platelets and in releasate of washed canine platelets yielded estimates of platelet vWf at approximately 2% of circulating vWf in this species, with approximately 15% of this being released into the fluid phase on activation. This contrasts with findings in humans, in which approximately 10%-25% of circulating vWf is compartmentalized in platelets. The difference in relative levels of canine and human platelet vWf could not be accounted for by differences in platelet ultrastructure. The decreased relative level may account for reports that canine platelets contain no vWf.

Animals↗
PubMed1988

Cyclosporine v methotrexate for graft-v-host disease prevention in patients given marrow grafts for leukemia: long-term follow-up of three controlled trials.

One hundred seventy-nine patients with acute nonlymphoblastic leukemia in first remission (n = 75), chronic myelocytic leukemia in chronic or accelerated phase (n = 48) or leukemia in advanced stage (n = 56) were given HLA-identical marrow grafts and randomized to receive methotrexate or cyclosporine for prevention of graft-v-host disease (GVHD). The current report updates the three prospective trials with follow-ups ranging from 3.2 to 6.2 years after marrow grafting. Results were analyzed separately for each individual study and for all three studies combined. Overall, 40% of patients given cyclosporine and 55% of those given methotrexate developed acute GVHD (P = .13); the incidence of chronic GVHD was 42% and 48%, respectively (P = .67). Twenty-two percent of cyclosporine-treated patients and 30% of methotrexate-treated patients developed interstitial pneumonia of any etiology (P = .25), and the figures for cytomegalovirus pneumonia were 18% and 20%, respectively (P = .41). The overall incidence of leukemic relapse was 31% in cyclosporine-treated patients and 36% in methotrexate-treated patients (P = .75). The probabilities of survival for cyclosporine-v methotrexate-treated patients were comparable for all three study groups: 52% v 48% in patients with acute nonlymphoblastic leukemia (P = .42), 55% v 60% for those with chronic myelocytic leukemia (P = .61), 12% and 12% for those with advanced leukemia (P = .93), and 39% v 38% overall (P = .72). We conclude that cyclosporine and methotrexate are comparable regarding the likelihood of acute/chronic GVHD, interstitial pneumonia, leukemic relapse, and long-term survival.

Acute Disease↗
PubMed1987

Recovery of thrombopoietin during purification.

A thrombocytopoiesis-stimulating factor (TSF or thrombopoietin) was previously purified by a six-step purification procedure. However, the exact quantity of TSF that was recovered, through the various purification procedures, was unknown because of the absence of a method for establishing a unit of measure of TSF. In the present work dose-response relationships on both the crude TSF preparations and on the more highly purified TSF were determined. TSF units were calculated from the dose-response curves. A unit of TSF is defined as the amount of material (mg) that is required to increase the percentages 35S incorporation into platelets of immunothrombocythemic mice by 50% above the baseline. The results of determining the TSF units on the crude TSF preparation indicated that 0.11 unit (U) of TSF/mg protein was present. Results showed that the specific activity of TSF can be increased to about 3.6 U/mg by a single purification procedure using Sephadex G-75 column chromatography. Increased specific activities were obtained by additional purification steps, i.e., DEAE-cellulose column chromatography, SE-HPLC, DEAE-HPLC, and SDS-PAGE. The purified product appears to have a specific activity of about 11,000 U/mg of protein with 0.00003% of the protein and 1.1% of the TSF recovered from the starting material. Establishing a unit of measure for TSF will allow calculations of its degree of purity, provide a method for quantitation of recoveries of activities after various purification procedures, and allow comparisons of results from different experiments and different laboratories.

Animals↗
PubMed1987

Comparison of horseradish peroxidase and alkaline phosphatase-labelled antibodies in enzyme immunoassays.

The periodate method was found to be most effective for preparing horseradish peroxidase-sheep anti-human and horseradish peroxidase-donkey anti-mouse immunoglobulin (IgG) conjugates. The conjugates were improved by carrying out the oxidation of the enzyme at low pH. Anti-human and anti-mouse IgG-peroxidase conjugates (0.5 mg/mL IgG and 0.7 mg/mL IgG, respectively) were used at 1:15,000 and 1:8000 dilutions, respectively, in a sandwich ELISA to detect human and mouse IgG in buffer or in a growth medium containing 20% foetal calf serum. Using the peroxidase conjugates, it was possible to detect human and mouse IgG at concentrations as low as 1 ng/mL. The glutaraldehyde method was found to be much more effective than the periodate method for conjugating alkaline phosphatase to the antibodies. The optimum dilutions for anti/human and anti-mouse IgG-alkaline phosphatase conjugates (0.18 mg/mL IgG and 0.3 mg/mL IgG, respectively) in ELISA were 1:500 and 1:1000, respectively. The detection limit with alkaline phosphatase conjugates was 7 ng/ml for human IgG and 4 ng/ml for mouse IgG.

Alkaline Phosphatase↗
PubMed1987

Marrow transplantation for patients with acute lymphoblastic leukemia in first marrow remission.

Forty-six patients with acute lymphoblastic leukemia (ALL) in first marrow remission underwent allogeneic marrow transplantation between August 1976 and June 1985. Thirty-four patients had no extramedullary disease after remission induction and 12 had extramedullary relapses prior to or at the time of marrow grafting. The conditioning regimen included cyclophosphamide followed by total body irradiation, 9.2-15.75 Gy, administered as a single dose or in six or seven daily fractions. Marrow donors were genotypically HLA-identical siblings. Methotrexate was given as prophylaxis for graft-versus-host disease (GVHD). Forty-four patients had marrow engraftment. The incidence of grades II-IV acute GVHD was 52%. Clinical chronic GVHD occurred in 21 patients. Eighteen patients are alive 1-9 years (median = 4.2 years) after marrow grafting, 15 of whom are in continuous complete remission. The estimated probability of relapse within 2 years (+/- standard error) is 41 +/- 9% and the probability of relapse-free survival at 5 years is 28 +/- 7%. Major causes of death were recurrent leukemia, acute GVHD and interstitial pneumonia. Actuarial probabilities of survival, relapse and disease-free survival were not significantly different between those patients who did and those who did not have extramedullary disease after attaining first marrow remission.

Bone Marrow Transplantation↗
PubMed1987

Preparation of red-blood-cell-depleted marrow for ABO-incompatible marrow transplantation by density-gradient separation using the IBM 2991 blood cell processor.

Thirty patients who had major ABO blood group incompatibility with their HLA-matched donors underwent allogeneic marrow transplantation after removal of red blood cells (RBC) from donor marrow by Ficoll-Diatrazoate (F-D) separation using the IBM 2991 blood cell processor. We selected the IBM 2991 because we were interested in obtaining information about RBC-depleted mononuclear cells for monoclonal antibody and complement incubation of marrow. The median residual marrow RBC volume was 2.6 ml (1.2% of the original volume) and marrow infusion was well tolerated in every instance. The median doses of nucleated and mononuclear cells were 8.7 X 10(7)/kg and 2.2 X 10(7)/kg recipient weight, respectively, representing median marrow total nucleated and mononuclear cell losses of 63.4% and 52.9%, respectively. The median CFU-GM loss was 52.4%. Four patients died 13-21 days after marrow infusion and were unevaluable for engraftment. One patient failed to achieve engraftment and received a second transplant on day 36 from a second donor. One patient with myelofibrosis had poor engraftment and died on day 177 with low peripheral blood counts. For evaluable patients, no significant differences were observed in the rate of recovery of peripheral blood granulocyte or platelet counts between those receiving RBC-depleted marrow or ABO-matched unprocessed marrow. However, posttransplant red cell transfusion requirements were increased and transfusion independence delayed in patients receiving RBC-depleted marrow as compared to patients receiving unprocessed marrow. We concluded that red cell depletion using the IBM 2991 was effective in removing red cell, but resulted in significant and variable hematopoietic cell losses which may have contributed to graft failure in at least one patient. Such cell losses appear to be inherent in both manual and semiautomated methods for F-D cell separation.

ABO Blood-Group System↗
PubMed1986

Methotrexate and cyclosporine compared with cyclosporine alone for prophylaxis of acute graft versus host disease after marrow transplantation for leukemia.

We treated 93 patients who had acute nonlymphoblastic leukemia in the first remission or chronic myelocytic leukemia in the chronic phase (median age, 30 years) with high-dose cyclophosphamide and fractionated total-body irradiation, followed by infusion of marrow from an HLA-identical sibling. To evaluate postgrafting prophylaxis for graft versus host disease, we studied these patients in a sequential, prospective, randomized trial that compared the effect of a combination of methotrexate and cyclosporine (n = 43) with that of cyclosporine alone (n = 50). All patients had evidence of sustained engraftment. A significant reduction in the cumulative incidence of grades II to IV acute graft versus host disease was observed in the patients who received both methotrexate and cyclosporine (33 percent), as compared with those who were given cyclosporine alone (54 percent) (P = 0.014). Seven patients who received cyclosporine alone acquired grade IV acute graft versus host disease, as compared with none who received both methotrexate and cyclosporine. Thirty-five of the 43 patients given both methotrexate and cyclosporine and 31 of the 50 patients given cyclosporine are alive as of this writing, at 4 months to 2 years (median, 15 months); the actuarial survival rates in the two groups at 1.5 years were 80 percent and 55 percent, respectively (P = 0.042). We conclude that the combination of methotrexate and cyclosporine is superior to cyclosporine alone in the prevention of acute graft versus host disease after marrow transplantation for leukemia, and that this therapy may have a beneficial effect on long-term survival.

Acute Disease↗
PubMed1986

Monoclonal antibodies to human urinary thrombopoietin.

Monoclonal antibodies (MA) to a thrombocytopoiesis-stimulating factor (TSF or thrombopoietin) were obtained from hybridomas derived from the fusion of P3 X 63/Ag 8 cells and spleen cells from TSF-immunized BALB/c mice. The immunizing protein was a partially purified TSF-rich preparation from the urine of a thrombocytopenic patient, and was shown to stimulate platelet production in rebound-thrombocytotic mice; i.e., platelet counts of recipient mice were increased to 133% of control and the values for percentage 35S incorporation into platelets were elevated to 225% of control. Media from several hybrid cultures were tested in a microantibody detection technique that measured the binding of MA to a 125I-purified TSF preparation from human embryonic kidney (HEK) cells. The immune complex was precipitated by the addition of goat anti-mouse IgG serum and centrifugation. One clone gave 25% binding of 125I-TSF after a sevenfold dilution of the medium. This cell line was recloned and four of the subclones produced MA that gave even greater binding capacities. Hybridized cells were injected into "pristane-primed" mice and the antibodies produced in the ascites fluid were also shown to bind the 125I-TSF. Compared to the results of normal mouse serum, ascites fluid containing MA was shown to bind the unlabeled TSF from HEK cells. The TSF activity was significantly reduced in the supernatant fluid after precipitating the TSF-anti-TSF immune complex by a second antibody when tested in an immunothrombocythemic mouse assay. After SDS-PAGE, the precipitate from this TSF-MA conjugate showed that the antiserum bound a single 32,000 mol wt component, indicating the monospecificity of the MA. MA directed toward human TSF will allow studies that were not previously possible.

Animals↗
PubMed1986

Effects of hypoxia on the small acetylcholinesterase-positive megakaryocyte precursor in bone marrow of mice.

The number of small acetylcholinesterase-positive (SAChE+) cells in the marrow of hypoxic mice was measured. Mice were exposed to 6-7% O2 levels by enclosure in cages covered with dimethyl-silicone rubber membranes for 1-14 days. The mice showed a linear increase in packed cell volumes with time in the hypoxic atmosphere, but platelet counts showed a characteristic biphasic response, i.e., increased platelet counts were observed after 1-3 days of hypoxia, and significantly (P less than 0.05-P less than 0.0005) decreased platelet counts were observed thereafter (6-14 days). The total number of megakaryocytes in the marrow of hypoxic mice decreased significantly (P less than 0.005) with time. In agreement with the data on platelet counts, hypoxia caused the total number of SAChE+ cells in the marrow of mice to be biphasic. At Day 2 there was a significant increase (P less than 0.05) in the total number of SAChE+ cells/mm3 of bone marrow; however, by days 10-14 the numbers had decreased markedly (P less than 0.005). These data indicate that hypoxia decreases platelet production by action on a precursor cell to the SAChE+ cell. The hypoxia-induced thrombocytopenia is probably caused by stem-cell competition between the erythrocytic and megakaryocytic cell lines.

Acetylcholinesterase↗
PubMed1986

Marrow transplantation for severe aplastic anemia: methotrexate alone compared with a combination of methotrexate and cyclosporine for prevention of acute graft-versus-host disease.

Forty-six patients with severe aplastic anemia (median age, 23 years) were treated with high-dose cyclophosphamide followed by infusion of marrow from an HLA-identical family member. To evaluate postgrafting prophylaxis for graft-v-host disease (GVHD), they were entered into a prospective randomized trial comparing the effect of a combination of methotrexate and cyclosporine (n = 22) to that of methotrexate alone (n = 24). Forty-four of the forty-six patients had evidence of sustained marrow engraftment. Only one patient in each of the two study groups showed graft rejection. A significant reduction in the cumulative incidence of grades II to IV acute GVHD was seen in patients given methotrexate/cyclosporine (18%) compared with those given methotrexate alone (53%) (P = .012). In three patients given methotrexate alone, grade III developed, and in six, grade IV acute GVHD developed, compared with none given methotrexate/cyclosporine. Eighteen of the 22 patients given methotrexate/cyclosporine and 15 of the 24 given methotrexate alone are alive between 5.5 and 44.5 months (median, 18 months), with actuarial survival rates at 2 years of 82% and 60%, respectively (P = .062). The incidence of fatal infections was higher in patients given methotrexate alone, whereas there are as yet no significant differences in the incidence of chronic GVHD. We conclude that methotrexate/cyclosporine treatment resulted in a significant decrease in the incidence and severity of acute GVHD in patients who received transplants for severe aplastic anemia and thus an improvement in survival.

Acute Disease↗
PubMed1985

Marrow transplantation for leukemia following fractionated total body irradiation. A comparative trial of methotrexate and cyclosporine.

Fifty-six patients, 30-47 yr of age, with leukemia in relapse received allogeneic marrow transplants from HLA-identical siblings. All patients were treated with cyclophosphamide (120 mg/kg) and 7 daily fractions of 2.25 Gy of total body irradiation (TBI) for seven consecutive days. Nine patients (16%) are currently alive and free of disease 324-845 days from transplantation. The actuarial relapse and survival rates at 2 yr were 56% and 9.5% respectively. These data were not remarkably different from those in previous studies using 10 Gy of TBI administered as a single dose. Thirty patients were randomized to receive methotrexate (MTX) and 26 to receive cyclosporine (CSP) as postgrafting prophylaxis for acute graft-versus-host disease (GVHD). The probability of developing significant acute GVHD by day 100 post-transplant was 71% for patients in the MTX group and 45% for patients in the CSP group (p less than 0.05). The probability of relapse was 37% for patients in the MTX group and 70% for patients in the CSP group (p less than 0.05). Transplant-related deaths were more frequent in the MTX group and leukemic deaths were more frequent in the CSP group although this may have been related to an uneven distribution of high-risk patients. Long-term disease-free survival was comparable. Patients in the MTX group had more severe mucositis, more alveolar pneumonias and possibly more deaths due to complications of acute and chronic GVHD. Patients in the CSP group had a higher incidence of hypertension, neurological complications and renal dysfunction.

Adult↗
PubMed1985

Design and use of double lumen right atrial catheters in bone marrow transplant recipients.

Bone marrow transplant recipients require central venous catheterization for a variety of fluids. They are also particularly susceptible to infection. Here we discuss the use of double lumen catheters to reduce the number of invasions necessary. We make particular reference to infection, neutropenia, prophylactic antibiotics, additional catheters, and presence of graft vs host disease.

Adolescent↗
PubMed1985

Autologous marrow transplantation in patients with acute nonlymphocytic leukemia in first remission.

Thirteen patients with acute nonlymphocytic leukemia underwent autologous bone marrow transplantation (ABMT) following high doses of cyclophosphamide and total body irradiation while in first complete remission. After marrow infusion four patients received human leukocyte interferon and nine received intravenous methotrexate. One patient died on day 16 of septicemia associated with severe gastrointestinal toxicity. In the remaining 12 patients the median day of achieving a circulating granulocyte level of 500/mm3 was 29 (range 15-94 days). Eight of 12 evaluable patients achieved a sustained platelet count of 20,000/mm3 or greater in a median of 44 days (range 12-116 days) and four patients did not achieve this level before death on days 116-396. One patient died on day 116 of interstitial pneumonitis secondary to cytomegalovirus. Eight patients relapsed 58-365 days after AMBT (median 335 days), and all have died. Three patients are alive and well without relapse 26-50 months after ABMT. This study demonstrated that poor engraftment was a frequent complication of ABMT when early posttransplant cytotoxic therapy was attempted. Relapse of leukemia and the number of long-term survivors in this small group of patients was not different from that expected following conventional therapy.

Acute Disease↗