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Biomedical subjects

R M Fox

Publications and source records attributed to R M Fox.

At least 55 records · Page 3Linked to original sources
PubMed1995

Human gene for the large subunit of ribonucleotide reductase (RRM1): functional analysis of the promoter.

Ribonucleotide reductase comprises two nonidentical protein subunits R1 and R2, both of which are required for enzyme activity and show cell cycle-dependent regulation. The TATA-less promoter of the human RRM1 gene (encodes R1 protein) was examined with reference to regulatory domains upstream of the transcription start site. A region from nt -195 to +3 was found to give maximal expression of a reporter gene when transfected into the human cell line K562. Overall, this 198-bp region shows 58% identity with the equivalent region of the murine promoter; however, it contains two 22-bp domains that were 81 and 91% identical between species. Electrophoretic mobility shift assays were performed using a fragment of the domain closest to the transcription start site. These experiments revealed that several factors were able to bind this region in a sequence-specific manner. One of these factors was shown to be Sp1 by specific competition and supershift using antibody to Sp1. The data presented suggest that Sp1 is involved in the transcription of RRM1.

Animals↗
PubMed1995

Sequential changes in serum iron and ferritin in patients undergoing high-dose chemotherapy and radiation with autologous bone marrow transplantation: possible implications for treatment related toxicity.

In an effort to define the pattern of iron flux during high-dose chemotherapy or chemo/radiotherapy, we prospectively measured serum iron, iron binding capacity, and ferritin in patients undergoing autologous bone marrow transplantation for various malignancies. Sequential measurement of serum iron from days -7 to +12 was carried out in 88 evaluable patients, and simultaneous measurement of iron, ferritin, and total iron binding capacity was carried out in 32 patients. We found that there was a predictable rise in serum iron on day -2 or -3, and that this was accompanied by an increase in the saturation of transferrin. In addition, there was a similar increase in serum ferritin levels, which peaked by day +2. We suggest that the timing of this change in serum iron and saturation of transferrin may be important in mediating endothelial cell damage and, hence, organ toxicity in the setting of AuBMT. Based on these findings, we suggest that large clinical studies could be a source of patient samples to measure surrogate endpoints such as lipid peroxidation products (malondialdehyde or isoprostanes), or protein oxidation products following high-dose chemo/radiotherapy to determine the role of iron in cellular injury. It is possible that pharmacological manipulations to reduce free radical production or to chelate iron during the days prior to bone marrow reinfusion might help to reduce tissue injury in the setting of bone marrow transplantation.

Adolescent↗
PubMed1995

Acute cholecystitis after autologous bone marrow transplantation for acute myeloid leukemia.

BACKGROUND: We investigated the incidence of acute cholecystitis in patients with acute myeloid leukemia (AML) undergoing autologous bone marrow transplantation in complete remission. PATIENTS AND METHODS: Thirty-five consecutive acute myeloid leukemia patients were given oral busulfan 4 mg/kg/day for 4 days and IV cyclophosphamide 50 mg/kg/day for 4 days followed by reinfusion of autologous bone marrow purged with 4-hydroperoxycyclophosphamide. RESULTS: Five of 35 patients developed clinical evidence of acute cholecystitis, manifested by fever, nausea, vomiting, right-upper-quadrant pain, and abdominal guarding, within 18 days after autologous bone marrow infusion. Ultrasonography and CT scans of the abdomen supported the diagnosis of cholecystitis. Three patients underwent cholecystectomy, while two patients were treated medically; all recovered uneventfully. A review of 338 consecutive bone marrow transplant patients who underwent marrow transplantation for a variety of diseases and were treated with other high-dose cytotoxic regimens during the same time period revealed significantly fewer cases of cholecystitis, i.e. two, (p < 0.0001). CONCLUSIONS: Five of 35 AML patients undergoing autologous bone marrow transplant using busulfan, cyclophosphamide, and purged bone marrow developed evidence of acute cholecystitis. These findings suggest that the busulfan/cyclophosphamide preparative regimen may be associated with acute cholecystitis. The true incidence of this injury and its pathogenesis remain to be elucidated.

Acute Disease↗
PubMed1994

Filgrastim in patients with chemotherapy-induced febrile neutropenia. A double-blind, placebo-controlled trial.

OBJECTIVE: To determine if filgrastim (recombinant human methionyl granulocyte colony-stimulating factor) used in addition to standard inpatient antibiotic therapy accelerated recovery from infection associated with chemotherapy-induced neutropenia. DESIGN: Randomized, double-blind, placebo-controlled trial. SETTING: Hematology and oncology wards of four teaching hospitals. PATIENTS: 218 patients with cancer who had fever (temperature > 38.2 degrees C) and neutropenia (neutrophil count < 1.0 x 10(9)/L) after chemotherapy. INTERVENTION: Patients were randomly assigned to receive filgrastim (12 micrograms/kg of body weight per day) (n = 109) or placebo (n = 107) beginning within 12 hours of empiric therapy with tobramycin and piperacillin. Patients received treatment and remained in the study until the neutrophil count was greater than 0.5 x 10(9)/L and until 4 days without fever (temperature < 37.5 degrees C) had elapsed. MEASUREMENTS: Days of neutropenia and fever and days in the study (hospitalization); time to resolution of fever and febrile neutropenia; and frequency of the use of alternative antibiotics. RESULTS: Compared with placebo, filgrastim reduced the median number of days of neutropenia (3.0 compared with 4.0 days of a neutrophil count of < 0.5 x 10(9)/L; P = 0.005) and the time to resolution of febrile neutropenia (5.0 compared with 6.0 days; P = 0.01) but not days of fever (3.0 days for both groups). The frequency of the use of alternative antibiotics was similar in the two groups (46% compared with 41%; P = 0.48). The median number of days patients were hospitalized while on study was the same (8.0 days; P = 0.09); however, filgrastim decreased the risk for prolonged hospitalization (> 11 days, 4th quartile) by half (relative risk, 2.1 [95% CI, 1.1 to 4.1]; P = 0.02). In exploratory subset analyses, filgrastim appeared to provide the greatest benefit in patients with documented infection and in patients presenting with neutrophil counts of less than 0.1 x 10(9)/L. CONCLUSIONS: Filgrastim treatment used with antibiotics at the onset of febrile neutropenia in patients with cancer who have received chemotherapy accelerated neutrophil recovery and shortened the duration of febrile neutropenia.

Adolescent↗
PubMed1994

Human R1 subunit of ribonucleotide reductase (RRM1): 5' flanking region of the gene.

Ribonucleotide reductase is essential, in dividing cells, for the production of deoxyribonucleotides prior to DNA synthesis in S phase. Neither of its two subunits (R1 and R2) are detectable in quiescent cells. In cycling cells, RRM1 mRNA and R1 protein are present throughout the cell cycle. A fragment of the human cDNA was used to isolate a genomic clone that encompasses the 5' flanking region of human RRM1. Primer extension and PCR experiments were used to define six potential cap sites. The immediate upstream region does not have a TATA box and is not GC-rich. A 1.9-kb fragment (-1670 to +208) was able to direct transcription of a reporter gene in a transient expression system. Understanding the mechanisms regulating expression of this gene will provide insight into the processes involved in cell cycling and may be of particular importance in understanding the deregulated growth of transformed cells.

Amino Acid Sequence↗
PubMed1994

Marrow cellularity as a predictor of adequate cell yield for transplantation.

Clear correlations have not been established between bone marrow cellularity before or at marrow harvest and marrow cell yield for transplantation. The authors therefore retrospectively reviewed 204 marrow donations to ascertain whether biopsy cellularity was predictive of nucleated cell yield at harvest, as measured by final cell counts (FCC)/kg body weight. Preharvest and intraoperative biopsy cellularity were highly correlated with each other; moderate correlation was found between intraoperative biopsy cellularity and FCC. Mean cellularity was slightly but significantly higher in samples yielding an FCC greater than 2 x 10(8) nucleated cells/kg (P < 0.01). Biopsy cellularity less than 20%, seen in 4% of specimens, did not consistently correlate with low FCC, defined as less than 2 x 10(8) nucleated cells/kg. More than 2 x 10(8) cells/kg were consistently obtained only when biopsy cellularity was 65% or more. Marrow biopsies performed before harvest can be used to predict intraoperative cell counts at the time of marrow donation, although a cell yield of more than 2 x 10(8) nucleated cells/kg can be assured only with high marrow cellularity.

Adolescent↗
PubMed1994

Randomized comparison of MACOP-B with CHOP in patients with intermediate-grade non-Hodgkin's lymphoma. The Australian and New Zealand Lymphoma Group.

PURPOSE: To compare complete response rates, time to failure, survival, and toxicity for patients with intermediate-grade non-Hodgkin's lymphoma (NHL) treated with cyclophosphamide, doxorubicin, vincristine, and prednisolone (CHOP) versus those treated with a regimen consisting of methotrexate, doxorubicin, cyclophosphamide, vincristine, prednisolone, and bleomycin (MACOP-B), in a multicenter, randomized controlled trial performed by 22 centers of the Australian and New Zealand Lymphoma Group (ANZLG). PATIENTS AND METHODS: Between October 1986 and June 1991, 304 patients were randomized, of whom 236 were eligible for analysis. Eligibility criteria included diffuse small cleaved-cell, diffuse mixed small- and large-cell, follicular large-cell, diffuse large-cell, and large-cell immunoblastic, stages I bulky or II to IV. RESULTS: There was no significant difference in complete response rates (51% for MACOP-B v 59% for CHOP), failure-free survival, or overall survival in the two treatment arms. The rate of death of MACOP-B patients relative to CHOP patients was estimated to be 0.91 (P = .64) when stratified by prognostic group. There were no significant differences between the two regimens in any of the prognostic subgroups. Toxicity was significantly more severe with MACOP-B, particularly cutaneous toxicity, stomatitis, and gastrointestinal ulceration. The average relative dose-intensity (RDI) of MACOP-B was 0.91 and of CHOP was 0.90, indicating good dose delivery in this multicenter group setting. CONCLUSION: CHOP chemotherapy produced results equivalent to those of MACOP-B in patients with intermediate-grade NHL and with significantly fewer toxic complications. Despite relatively poor results in some patient subgroups, CHOP remains the standard chemotherapy for this disease, against which all new regimens should be compared.

Adolescent↗
PubMed1994

Colony-stimulating factors. Present status and future potential.

Granulocyte colony-stimulating factor (G-CSF) and granulocyte-macrophage colony-stimulating factor (GM-CSF) have been used successfully to enhance neutrophil recovery in patients with various malignancies undergoing standard or high dose chemotherapy, with or without autologous or allogeneic bone marrow transplantation support, and offer potential advantages in these settings in terms of reducing the total costs of healthcare and/or improving therapeutic outcomes. Clinical trials are now aimed at identifying which patients and which nonhaematological malignancies will respond best to colony-stimulating factor (CSF) support, and which of the 2 factors is the most appropriate in each setting. Two areas of considerable interest at present are the potential for chemotherapy dose optimisation and intensification with CSF therapy, and the use of CSFs to permit the harvest and reinfusion of peripheral blood progenitor cells as an alternative to autologous or allogeneic bone marrow transplantation. In the case of dose-intensified chemotherapy, costs of treatment increase but the gain may be an increase in survival rates or disease-free intervals. The potential of G-CSF and GM-CSF therapy in other conditions, notably haematological malignancies such as myelodysplasia and myeloid leukaemias, and AIDS, means that these agents are likely to make a significant impact on the treatment of a wide range of debilitating conditions in the future.

Animals↗
PubMed1994

Hepatic dysfunction in patients with carcinoma who are severely thrombocytopenic and immunosuppressed.

BACKGROUND: The use of intensive cytotoxic drug therapy for malignant disorders often results in hepatic dysfunction. It is important to determine the cause of hepatic injury to institute appropriate therapy; however, neutropenia and thrombocytopenia may prevent performance of hepatic biopsy to establish a cause. STUDY DESIGN: We prospectively evaluated the cause of hepatic dysfunction using laparoscopic biopsy of the liver in 20 consecutive patients who were receiving intensive cytotoxic therapy, with or without bone marrow transplantation, or who were being treated for severe aplastic anemia. One to three direct-vision laparoscopic biopsies were performed in each patient during general anesthesia and bleeding was controlled with spatula electrocautery. Platelet concentrate transfusions were given before, during, and immediately after the biopsy. RESULTS: Platelet and leukocyte counts at the time of hepatic biopsy ranged from 1,000 to 83,000 per microL (median of 23,500 per microL) and zero to 14,300 per microL (median of 2,200 per microL), respectively. Nineteen of 20 patients had platelet counts of less than 68,000 per microL. Bleeding at biopsy site was controlled during the procedure without evidence of bleeding or complications after biopsy. Biopsy specimens revealed graft-versus-host disease (n = 2), hepatic veno-occlusive disease (n = 1), steatosis (n = 5), cholestasis (n = 19), hemosiderosis (n = 19), and granuloma (n = 1). CONCLUSIONS: In several patients, the knowledge derived from hepatic biopsy results altered the therapeutic strategy. The use of laparoscopic hepatic biopsy to assess the cause of hepatic dysfunction should be encouraged because it is a safe procedure, even in patients who are severely thrombocytopenic and immunocompromised.

Adolescent↗
PubMed1993

Calcium antagonists and Bay K8644 promote depolarization of the rat heart mitochondrial membrane potential. Further evidence for a role in alteration of oxidative metabolism.

Studies were carried out using a tetraphenylphosphonium (TPP+)-selective electrode to monitor the effect of selected calcium (Ca2+) antagonists and the dihydropyridine Ca2+ agonist Bay K8644 on membrane potential (psi) associated with isolated rat heart mitochondria. Verapamil and diltiazem (10-500 microM), standard Ca2+ antagonists, produced a depolarization of both liver and heart mitochondria at concentrations > 150 microM. In contrast, nitrendipine (10-200 microM), a dihydropyridine compound, produced a concentration-related inhibition of psi in mitochondria from both sources, effects which were statistically significant at concentrations > 50 microM. Cinnarizine (10-100 microM) and bepridil (10-100 microM) also produced inhibition of heart psi, these effects being particularly noted in the presence of bepridil, where depolarization of the membrane was statistically significant with only 10 microM drug. The results indicate the complexity of action of these drugs at the mitochondrial level. In general, drug actions on psi appear to be correlated with previously reported effects on Ca2+ transportation rather than oxidative phosphorylation associated with rat heart mitochondria. The findings also illustrate that the mitochondrial actions of cardiovascular compounds may be of relevance in situ, particularly during ischaemia/reperfusion when mitochondria become loaded with Ca2+.

3-Pyridinecarboxylic acid, 1,4-dihydro-2,6-dimethy↗
PubMed1993

Primary cerebral lymphoma: an argument for the use of adjunctive systemic chemotherapy.

Eleven patients with primary cerebral lymphoma were treated at a single institution over a 5 year period. Patient characteristics were typical of this rare disease. One patient died prior to receiving treatment and of the remaining 10, all received cranial irradiation and in addition, five received systemic cyclophosphamide, adriamycin, vincristine and prednisolone (CHOP) chemotherapy. Of the six patients who are alive and disease-free, five received the combined modality therapy. The median survival for those patients receiving cranial irradiation alone was 18 months and for the combined modalities was 25+ months. Combination systemic chemotherapy, in addition to cerebral irradiation, may convey a survival benefit in patients with primary cerebral lymphoma but this requires further investigation with multicentre, prospective randomized trials.

Adolescent↗
PubMed1993

Effect of peripheral blood progenitor cells mobilised by filgrastim (G-CSF) on platelet recovery after high-dose chemotherapy.

The haematopoietic growth factor (HGF), granulocyte colony stimulating factor (G-CSF; filgrastim) substantially shortens the period of severe neutropenia that follows high-dose chemotherapy and autologous bone marrow infusion by stimulating granulopoiesis. Filgrastim also increases numbers of circulating progenitor cells. We have studied the ability of filgrastim to mobilise peripheral blood progenitor cells (PBPC) and assessed their efficacy when infused after chemotherapy on recovery of neutrophil and platelet counts. Seventeen patients with non-myeloid malignant disorders received filgrastim (12 micrograms/kg daily for six days) by continuous subcutaneous infusion. Numbers of granulocyte-macrophage progenitors in peripheral blood increased a median of 58-fold over pretreatment values, and numbers of erythroid progenitors increased a median of 24-fold. Three leukapheresis procedures collected a mean total of 33 (SEM 5.7) x 10(4) granulocyte-macrophage progenitors per kg body weight. After high-dose chemotherapy in 14 of the patients (busulphan and cyclophosphamide), these cells were used to augment autologous bone marrow rescue and post-transplant filgrastim treatment. Platelet recovery was significantly faster in these patients than in controls who received the same treatment apart from the infusion of peripheral blood progenitors; the platelet count reached 50 x 10(9)/L a median of 15 days after infusion of haematopoietic cells in the study patients compared with 39 days in controls (p = 0.0006). The accelerated neutrophil recovery associated with filgrastim treatment after chemotherapy was maintained. Subsequently, 10 patients received filgrastim-mobilised PBPC without marrow after high-dose chemotherapy. The rate of platelet and neutrophil recovery in these patients was at least equal to that observed in the patients receiving PBPC and bone marrow.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗
PubMed1993

Comparison of preparative transplantation regimens using carmustine/etoposide/cisplatin or busulfan/etoposide/cyclophosphamide in lymphoid malignancies.

Most bone marrow transplantation preparative regimens use total body irradiation as one component. Recently, however, two non-total body irradiation containing autologous bone marrow transplantation preparative regimens have been evaluated in patients with lymphoid malignancies. The first regimen consisted of carmustine, etoposide, and cisplatin; some patients also received involved-field radiotherapy to sites of prior disease. Of the 79 patients with relapsed or refractory lymphoma who participated in this study, 57 (72%) achieved a complete remission and 40 (51%) remain in complete remission. Treatment-related deaths occurred in five patients (6%). The second preparative regimen evaluated consisted of busulfan, etoposide, and cyclophosphamide and included 21 patients with Hodgkin's lymphoma, non-Hodgkin's lymphoma, or acute lymphocytic leukemia. Sixteen patients (76%) achieved complete remission and 12 (57%) remain disease free. The regimen-related mortality rate in this study was 14%. The three treatment-related deaths were all due to pulmonary toxicity. The results of these clinical trials indicate that both the carmustine/etoposide/cisplatin regimen and the busulfan/etoposide/cyclophosphamide regimen are effective in treating lymphoid malignancies. Treatment-related toxicities and deaths are significant, but not prohibitive. Accordingly, these new preparative regimens deserve further evaluation in the treatment of patients with lymphoma or leukemia.

Adolescent↗
PubMed1992

Delay by internists in obtaining diagnostic biopsies in patients with suspected cancer.

OBJECTIVE: To investigate the degree and type of delays in performing diagnostic biopsies in medical patients with suspected malignancy. DESIGN: Retrospective survey of clinical histories of patients referred between January 1985 and March 1989. SETTING: Inner city teaching hospital internal medicine (non-oncologic) services. PATIENTS: Patients with gastrointestinal and lung cancers, adenocarcinoma of unknown primary site, and lymphomas were referred as inpatients by internists. Two hundred fifty-five patients were eligible, and 177 were evaluable. MAIN OUTCOME MEASURES: The number, type, and results of tests done before and after biopsy were analyzed. RESULTS: In 67% of patients the biopsied lesion was detected by the second day of evaluation; however, there was an 8- to 10-day delay before a biopsy was done. This delay was consistent across the four malignancy groups studied. Although logistic and other unavoidable delays occurred in 40% of the cases, in 60% delays could only be attributed to continued, frequently low yield, noninvasive tests. An average of 3.3 tests were made per patient, with only 24% leading to a definitive biopsy. CONCLUSION: Because of the performance of many other tests, a substantial delay exists in proceeding to biopsy during the diagnosis of cancer by internists.

Adenocarcinoma↗