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Biomedical subjects

N Ramsay

Publications and source records attributed to N Ramsay.

At least 37 records · Page 2Linked to original sources
PubMed1990

Comparison of two total body irradiation regimens in allogeneic bone marrow transplantation for acute non-lymphoblastic leukemia in first remission.

Between November 1976 and December 1987, 84 patients with newly diagnosed acute non-lymphoblastic leukemia who had achieved complete remission underwent non T-cell depleted allogeneic bone marrow transplantation from Human Leukocyte Antigen-Mixed Lymphocyte Culture (HLA-MLC) matched sibling donors. The first 36 patients (November 1976-June 1983) were prepared with cyclophosphamide, 60 mg/kg/day, IV for 2 days and single fraction total body irradiation with 750 cGy at a dose rate of 26 cGy/minute (Group I). The next 48 patients (July 1983-December 1987) were prepared with similar chemotherapy, but received hyperfractionated total body irradiation with total 1320 cGy, 165 cGy twice a day at a dose rate of 10 cGy/minute (Group II). Patient characteristics between these two groups are similar except for the significantly older age distribution in Group II. Median follow-up of Groups I and II are 8 years and 11 months and 2 years and 3 months, respectively. The Kaplan-Meier relapse-free survival, survival, and relapse rates at 3 years are 56, 58, and 19% in Group I and 69 (p = 0.22), 77 (p = 0.07), and 10% (p = 0.37) in Group II. There is no difference in the incidence of interstitial pneumonitis, viral or idiopathic, engraftment rate, or incidence of graft versus host disease (GVHD) between these two groups. The fractionated total body irradiation treated group had significantly less nausea and vomiting. Multivariate analysis shows that total body irradiation regimen is not a significant factor in regard to relapse rate, relapse-free survival, and survival.

Adolescent↗
PubMed1988

A mutant in a major heat shock protein of Escherichia coli continues to show inducible thermotolerance.

Escherichia coli cells carrying the dnaK756 mutation, were inactivated at 52 degrees C faster than control cells. This suggests that the intact dnaK gene product plays a role in protecting the cell from lethal damage at 52 degrees C. The effect of the dnaK mutation on induced thermotolerance was examined. Prior heat shock at 42 degrees C greatly lowered the subsequent inactivation rate in both mutant and control cells. This result suggests that, although produced in large amounts in response to thermal stress, mutation in the DnaK protein has little or no effect on induced thermotolerance.

Escherichia coli↗
PubMed1988

Bone marrow transplantation for poor prognosis neuroblastoma.

These studies suggest that intensive chemoradiotherapy (eg., VAMP-TBI), if given relatively soon after diagnosis and before development of progressive disease, improves long-term survival for patients with advanced neuroblastoma. Although this particular therapy is not useful for those who already have developed progressive disease, other intensive regimens may warrant testing in this latter group of patients. Our current study is testing aggressive induction chemotherapy, ex vivo purging of autologous marrow, and VAMP-TBI followed by BMT. Because of the increasing risk of progressive disease with time after diagnosis, we recommend beginning the BMT phase by 20 weeks after diagnosis. This should result in 85% of newly diagnosed patients entering the BMT phase without progressive disease; and, with fewer toxic deaths, 90% should survive the BMT phase. Thus, approximately 70% of patients could be disease-free survivors 8-9 months after diagnosis. Because a significant number of patients still develop progressive disease during induction or after BMT, efforts are being made to improve induction and pretransplant therapies and to identify prognostic factors. If modifications of the current regimens do not decrease the rate of progressive disease, it may be necessary to develop additional or different therapy for patients identified to be at high risk. Hopefully, new strategies will further increase the percentage of patients with tumor-free survival.

Bone Marrow Transplantation↗
PubMed1987

Therapy of chronic myelogenous leukemia with allogeneic bone marrow transplantation.

From December 1982 to January 1986, 57 patients received allogeneic bone marrow transplantation as therapy for Philadelphia chromosome (Ph') positive chronic myelogenous leukemia (CML). All patients were prepared for transplantation with cyclophosphamide 60 mg/kg (day -6, -5) and fractionated total body irradiation, 165 cGy twice daily (day -4, -3, -2, -1) and received major histocompatibility (MHC) matched donor marrow (day 0). All patients received graft-v-host disease (GVHD) prophylaxis with methotrexate, prednisone, and either antithymocyte globulin (ATG) (55 patients) or OKT3 infusion (two patients). The projected survival of 29 chronic phase patients is 64% (95% confidence interval [Cl] 42% to 86%); and of 28 accelerated phase patients, 30% (95% Cl, 12% to 48%) at 30 months (P = .005). Multivariate regression analysis of pretransplant patient characteristics demonstrated that the presence of chronic phase and age less than 30 years were the only prognostic features studied that independently predicted survival. No evidence of persistent or recurrent disease has occurred in chronic phase patients; however, reappearance of the Ph' was observed in seven accelerated-phase patients, and hematologic relapse occurred in three of these seven patients. The incidence of grade II to IV acute GVHD is 63% (95% Cl, 50% to 76%) at 100 days, and that of extensive chronic GVHD is 53% (95% Cl, 33% to 74%) at 30 months. The median Karnofsky activity assessment of survivors is 100% (range, 60% to 100%), and all activity assessments less than 100% can be attributed to complications of GVHD. Bone marrow transplantation therapy for CML after preparation with cyclophosphamide and fractionated total body irradiation results in a high proportion of disease-free survival in chronic-phase patients. Survival in accelerated phase is significantly worse and is associated with relapse. GVHD has emerged as a significant cause of morbidity and mortality in this study.

Antigens, Surface↗
PubMed1987

Unrelated donor bone marrow transplantation therapy for chronic myelogenous leukemia.

Eight patients received allogeneic bone marrow transplantation (BMT) as therapy for chronic myelogenous leukemia (CML) using marrow from unrelated donors. In all cases donors and recipients were HLA DR identical and had low MLC reactivity. In three cases recipients received marrow that was identical at the HLA A,B loci. In five cases HLA identity differed for one HLA A locus antigen. The unrelated donor search interval ranged from 2 to 28 months (median, 3 months). All recipients were prepared with a combination of cyclophosphamide, 60 mg/kg/d administered intravenously (IV) (days -6,-5) and with total body irradiation administered in 165 cGy fractions twice daily for four days (days -4, -3, -2, -1). Engraftment occurred in all cases (range, 18 to 48 days; median, 35 days), and return to a complete Philadelphia chromosome (Ph') negative state was documented in six of eight cases. Moderate or severe acute graft v host disease (GVHD) occurred in seven of eight cases, and extensive chronic GVHD in four of six evaluable recipients. A B cell lymphoproliferative disorder developed in one patient. Four recipients have died within 2 to 4 months of transplant. Four of eight patients survive at 11+ to 24+ months following transplantation (median, 15+ months) with normal peripheral blood counts and without evidence of leukemia. Current Karnofsky activity assessments are 90% or 100% in all survivors. Curative therapy of CML has been available only to the minority of patients eligible for sibling donor BMT. Unrelated donor BMT can be effective in the treatment of CML and may be particularly useful in this disorder since the prolonged stable phase of disease offers an opportunity to locate suitable donors.

B-Lymphocytes↗
PubMed1986

Deletion analysis of a DNA sequence that positions itself precisely on the nucleosome core.

Exonuclease III digests DNA sequentially from the 3' end. This enzyme is used to analyse the location of nucleosomes on DNA fragments containing a particular 145 base-pair (bp) sequence. When one of these fragments is assembled into chromatin and digested with exonuclease, a strong and persistent pause in digestion is detected at a single location. That this pause is due to the enzyme encountering a nucleosome is suggested, firstly, by its absence from digests of free DNA and, secondly, by the detection of a corresponding pause on the other strand. The two pauses, 146 bp apart, specify the location of a single precisely positioned nucleosome on the DNA fragment. This position corresponds exactly to one of two possible positions of the 145 bp sequence identified previously. A fragment containing only about 80 bp of the original 145 bp continues to position itself in the nucleosome like the parent sequence. Therefore, some of the sequence can be replaced with different DNA without affecting nucleosome positioning. Further exonuclease III analysis of an extensive set of deletions demonstrates that a central region of about 40 bp is essential for positioning the 145 bp sequence. When deletions advance into this region from either side, only a very small proportion of the DNA remains in the original position on the nucleosome. Therefore, the two short lengths of DNA at the edges of the region must each contain all or part of an essential nucleosome-positioning signal. These two critical sequences are symmetrically located across the nucleosome dyad and interact with the same region of histone H3. The sequence TGC occurs at the same place in both sequences; otherwise they are dissimilar.

Animals↗
PubMed1986

Cytomegalovirus infection after bone marrow transplantation: an association with acute graft-v-host disease.

Among 181 patients undergoing allogeneic bone marrow transplantation over a five-year period (1978 through 1982), cytomegalovirus (CMV) infection was a frequent and often lethal complication. Recipient pretransplant serology was the most important predictor of posttransplant CMV infection. CMV infection occurred in 26/137 seronegative recipients and in 28/44 seropositive recipients (P less than .001). Among patients who developed CMV infection, the time to infection was identical in seronegative and seropositive patients (median, 71 days post transplant). Bone marrow donor CMV serology did not significantly influence CMV infection rate. CMV infection was strongly associated with acute graft-v-host disease (AGVHD), occurring in 34/81 patients with AGVHD and 20/100 without GVHD (P less than .001). AGVHD preceded CMV infection by 33.7 days (mean) in patients developing both complications. Patients who developed CMV infections had also received more cellular blood products post transplant. These data suggest that CMV infection may occur through reactivation of latent virus (in seropositive recipients) or through exogenous exposure, possibly through transfused blood products, but that duration of immunoincompetence may be more critical than route of exposure in timing of clinically evident CMV infection. Prophylaxis tailored to the likely infectious source and more effective GVHD prevention both may be critical in preventing CMV infection after bone marrow transplantation.

Acute Disease↗
PubMed1985

Bone marrow transplantation for acute nonlymphocytic leukemia in first remission: analysis of prognostic factors.

Prognostic factors were reviewed retrospectively for 39 children and adults aged 1 to 40 years (median 14 years) with acute nonlymphocytic leukemia (ANLL) who attained a first remission and underwent bone marrow transplantation from November 1976 to July 1983. The preparation regimen for transplantation was cyclophosphamide (60 mg/kg/d for two days) followed by total body irradiation (either 750 cGy single dose at 26 cGy/min, n = 37, or 1,320 cGy fractionated at 10 cGy/min, n = 2). Twenty-three patients are surviving disease free with a median followup of three years. The three-year estimated disease-free survival is 55% +/- 17% (+/- 2 SE). Five patients have relapsed from 92 to 756 days after transplantation for an estimated relapse rate of 21% +/- 18%. Two factors, the white blood cell (WBC) count and the French-American-British (FAB) classification at leukemia diagnosis were found to be of prognostic importance. Patients with a WBC of less than 20,000/microL at diagnosis had a three-year estimated disease-free survival of 74% +/- 18% v 26% +/- 24% for those with a WBC of greater than or equal to 20,000 (P = .008). The estimated relapse rate was 6% +/- 12% for patients with a WBC at diagnosis less than 20,000 v 53% +/- 38% for patients with a WBC at diagnosis of greater than or equal to 20,000 (P = .01). Patients with myeloid morphology at diagnosis (FAB M1,2,3) had an estimated relapse rate of 9% +/- 12% v patients with monocytoid morphology (FAB M4,5a) whose estimated relapse rate was 58% +/- 44% (P = .05). Our data suggest that a high WBC count at poor prognostic factors for patients with ANLL who undergo bone marrow transplantation in first remission after conditioning with cyclophosphamide plus total body irradiation.

Acute Disease↗
PubMed1985

Autologous bone marrow transplantation for patients with acute lymphoblastic leukemia in second or subsequent remission: results of bone marrow treated with monoclonal antibodies BA-1, BA-2, and BA-3 plus complement.

Autologous bone marrow transplantation (BMT) was utilized as therapy for 23 patients with acute lymphoblastic leukemia (ALL) in second or greater remission. Bone marrow was treated in vitro with a combination of monoclonal antibodies, consisting of BA-1, BA-2, BA-3, and baby rabbit complement (BRC'). All patients were prepared for transplantation with cyclophosphamide and fractionated total body irradiation. Engraftment occurred in all 23 patients. Seven of 23 patients remain relapse-free from six to 32 months (median, 21.4 months) posttransplant. Failures were due to relapse with the exception of one patient who died of infection. This study demonstrates that autologous BMT using in vitro marrow treatment with BA-1, BA-2, BA-3, and BRC' is safe, allows engraftment, and results in prolonged survival for some patients with ALL in second or greater remission.

Adolescent↗
PubMed1984

Phage head assembly in bacteriophage T1.

Phage-related structures found in wild-type and mutant T1 infections were examined by sedimentation analysis, electron microscopy, and polyacrylamide gel electrophoresis. Phage-particle polypeptides P7 (molecular weight 33,000) and P11 (molecular weight 16,000) were identified as major head proteins and P10 (molecular weight 26,000) was shown to be the major tail protein. A DNA-free head-like structure containing P7 but not P11 was present in wild-type and a number of mutant infections. In view of its possible role as a precursor to mature heads, this structure was termed the prohead. Mutants in two genes, am10 (gene 13) and am45 (gene 14), synthesised only tails in nonpermissive infections. Mutants in eight of the head genes, am23 (gene 4), am283 (gene 13.3), am216 (gene 13.7), ts257 (gene 14.5), am11 (gene 15), am4 (gene 16), am7 (gene 17), and am30 (gene 18), synthesised proheads and tails but not other structures. am37 (gene 12) synthesised proheads, tails, and empty heads. Studies with a tail-defective mutant suggested that empty heads were produced from the breakdown of DNA-filled heads. P11, the T1 gene 13.3 product, is analogous to the phage lambda gene D protein: both are major capsid proteins which appear to stabilise the later stages of head filling. These data are reviewed according to the general principles established for phage-head assembly and a tentative pathway for T1-head assembly is proposed.

Electrophoresis, Polyacrylamide Gel↗
PubMed1984

A 145-base pair DNA sequence that positions itself precisely and asymmetrically on the nucleosome core.

A 145-bp DNA sequence, cloned from Escherichia coli, was reconstituted into nucleosome core particles by a number of methods. The behaviour of the resulting complex upon sucrose gradient sedimentation and nucleoprotein gel electrophoresis closely resembled that of control bulk nucleosome core particles. DNase I digestion of the 32P-end-labelled complex revealed the 10-bp periodicity of cleavages expected for DNA bound on a histone surface. The narrow cleavage sites observed (1 bp wide) imply that the sequence occupies a single preferred position on the nucleosome core, accurate to the level of single base pairs. By relating the digestion pattern observed to the pattern of site protection found for random sequence nucleosomes, the DNA position was found to be offset by 17 bp from that in the normal core particle. A number of experiments argue against the involvement of length or end effects and suggest that it is some feature of the DNA sequence itself that determines this precise positioning of DNA on the nucleosome.

Animals↗
PubMed1984

Total parenteral nutrition in bone marrow transplantation: a clinical evaluation.

Bone marrow transplantation (BMT) is associated with severe metabolic stress secondary to anorexia, mucositis, enteritis, and infection. We compared nutritional parameters and clinical outcomes of 22 patients who received prophylactic total parenteral nutrition (TPN) to those of 22 controls, matched for age and diagnosis, who received nutritional support ad libitum. Over the 5-week study period, the TPN group averaged caloric intakes greater than 1.5 X basal energy expediture (BEE) per day and gained 2.5% of body weight; the control group averaged less than 0.9 X BEE and lost 3.7% of body weight. Visceral protein status as reflected by serum albumin was not different. Engraftment of donor marrow cells was 3 days earlier (p less than 0.01) in the TPN group than in the controls, despite there being no significant difference in the number of marrow cells each group received. There was no difference in the two groups' clinical outcomes; mortality, duration of hospital stay, and incidences of sepsis, graft-versus-host disease, and return of malignancy were equivalent. Thus, patients who received prophylactic TPN engrafted sooner than patients who did not; however, overall clinical outcome was unaffected by TPN. Controlled studies of prophylactic TPN are indicated for the BMT patient population.

Adolescent↗