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Biomedical subjects

R M Stone

Publications and source records attributed to R M Stone.

At least 55 records · Page 3Linked to original sources
PubMed1992

Hematopoietic growth factors and leukemia.

Hematopoietic growth factors, particularly granulocyte colony-stimulating factor and granulocyte-macrophage colony-stimulating factor, can be used as supportive agents to enhance bone marrow recovery after the administration of myelosuppressive chemotherapy given for nonmyeloid neoplasms. The use of these agents in the treatment of acute myeloid leukemia and myelodysplastic syndrome poses novel opportunities and challenges due to their direct effects on the neoplastic cells, which represent the transformed counterparts of normal hematopoietic stem cells. The interaction between hematopoietic growth factors and leukemic progenitor cells bearing a specific receptor for a given agent would be expected to result in proliferation, although maturation induction could occur. Hematopoietic growth factors have been employed as primary differentiating agents in myelodysplastic syndrome and as supportive agents after chemotherapy in acute myeloid leukemia. In either case, close monitoring for evidence of leukemic stimulation is required. Alternatively, pretreatment with colony-stimulating factors could induce cell cycling, thereby making the leukemic cells more susceptible to S-phase-specific chemotherapeutic agents, such as cytarabine.

Cell Cycle↗
PubMed1992

Risk factors for high-dose cytarabine neurotoxicity: an analysis of a cancer and leukemia group B trial in patients with acute myeloid leukemia.

PURPOSE: We analyzed pretreatment characteristics of patients with postremission acute myeloid leukemia (AML) treated with high-dose cytarabine (HIDAC) during a recent Cancer and Leukemia Group B (CALGB) trial to determine risk factors associated with HIDAC neurotoxicity. PATIENTS AND METHODS: One hundred seventy-six patients received at least one course of HIDAC as part of a CALGB protocol designed to determine the optimal dose of cytarabine (ara-C) for postremission treatment of AML. HIDAC consisted of 3 g/m2 ara-C infused over 3 hours at 12-hour intervals on days 1, 3, and 5. The pretreatment characteristics of 170 patients were available for risk analyses. RESULTS: Eighteen patients (10%) experienced neurotoxicity. Univariate analyses demonstrated associations between the occurrence of neurotoxicity and elevated serum creatinine, age, and alkaline phosphatase (AP). Multivariate analysis showed that these variables were independent risk factors. These findings were used to construct a risk model with the following parameters: creatinine greater than or equal to 1.2 mg/dL, age greater than or equal to 40 years, and AP greater than or equal to 3 x normal. Seventeen of 46 (37%) patients with two or more of these criteria developed neurotoxicity compared with one of 124 (1%) patients with one or none. The sensitivity and specificity of this model were 94% and 81%, respectively. CONCLUSION: We conclude that patients with two or more of the following parameters may be at increased risk for HIDAC neurotoxicity: (creatinine greater than or equal to 1.2 mg/dL, age greater than or equal to 40, and AP greater than or equal to 3 x normal). However, this model should be confirmed by analysis of additional groups of patients treated with HIDAC.

Acute Disease↗
PubMed1991

Inhibition of protein kinase C is associated with a decrease in c-myc expression in human myeloid leukemia cells.

Treatment of human myeloid leukemic cells with phorbol esters such as 12-O-tetradecanoylphorbol-13-acetate (TPA) is associated with activation and then partial down-regulation of protein kinase C activity. Previous work has suggested that the activation of protein kinase C by TPA contributes to the decrease in c-myc expression during differentiation of these cells. The present studies demonstrate that the decline in c-myc mRNA levels following exposure of HL-60 cells to TPA is preceded by an increase in expression of this gene. In contrast, exposure of HL-60 cells to inhibitors of protein kinase C activity is associated with down-modulation of c-myc expression. Similar findings have been obtained in U-937 myeloid leukemia cells. Taken together, these findings suggest that phorbol esters have a biphasic effect on c-myc expression. Whereas the activation of protein kinase C by phorbol esters may be associated with an increase in c-myc gene expression, the subsequent partial down-regulation of kinase activity may initiate a cascade of events resulting in the down-modulation of c-myc expression.

1-(5-Isoquinolinesulfonyl)-2-Methylpiperazine↗
PubMed1991

Expression of the jun-B gene during induction of monocytic differentiation.

The AP-1 protein complex binds to specific DNA sequences that regulate transcription of genes responsive to certain growth factors and phorbol esters. This complex is composed of products of the jun and fos gene families. The present studies have examined the effects of 12-O-tetradecanoylphorbol-13-acetate (TPA) on the regulation of jun-B gene expression during induction of monocytic differentiation. Low levels of jun-B transcripts were present in uninduced HL-60 promyelocytic leukemia cells. In contrast, treatment with TPA was associated with rapid increases in jun-B mRNA levels that were maximal at 3 h and remained elevated at 48 h. The induction of jun-B expression by TPA in these cells preceded that of the c-jun and c-fos genes. Similar increases in jun-B transcripts were detectable in TPA-treated THP-1 and U-937 myeloid leukemia cells, although expression of this gene was transient in the more differentiated THP-1 cells. Run-on assays demonstrated low levels of jun-B gene activation in untreated HL-60 cells, whereas TPA treatment was associated with a 6-fold increase in the transcription rate of this gene. This induction of jun-B expression occurred in the absence of de novo protein synthesis. In contrast, inhibition of protein synthesis was associated with superinduction of TPA-induced jun-B mRNA levels and an increase in stability of this transcript. These findings suggest that jun-B gene expression is regulated at both the transcriptional and posttranscriptional levels during induction of monocytic differentiation.(ABSTRACT TRUNCATED AT 250 WORDS)

Bryostatins↗
PubMed1990

Inhibition of phorbol ester-induced monocytic differentiation and c-fms gene expression by dexamethasone: potential involvement of arachidonic acid metabolites.

The treatment of human U-937 leukemia cells with 12-O-tetradecanoylphorbol-13-acetate (TPA) is associated with induction of monocytic differentiation. However, the signaling pathways responsible for induction of the differentiated monocytic phenotype remain unclear. The present studies demonstrate that dexamethasone blocks TPA-induced U-937 cell growth inhibition, adherence, and alpha-naphthyl acetate esterase staining. The results also demonstrate that dexamethasone inhibits the appearance of c-fms transcripts associated with TPA treatment. Run-on transcription assays demonstrated that the c-fms gene is transcriptionally active in uninduced U-937 cells and that the rate of transcription is unchanged after dexamethasone and/or TPA treatment. These findings indicated that TPA increases c-fms expression by a dexamethasone-sensitive posttranscriptional mechanism. Treatment of U-937 cells with TPA was also associated with stimulation of arachidonic acid metabolism. Furthermore, dexamethasone, an inhibitor of phospholipase A2 activity, blocked TPA-induced increases in arachidonic acid release. These findings suggested that TPA may regulate certain features of monocytic differentiation, such as c-fms gene expression, through the formation of arachidonic acid metabolites. Indomethacin, an inhibitor of cyclooxygenase, had no detectable effect on c-fms gene expression. However, the cyclooxygenase metabolite, prostaglandin E2, inhibited the TPA-induced increases in c-fms mRNA levels. Taken together, the results indicate that TPA regulates c-fms gene expression by a dexamethasone-sensitive mechanism and that c-fms mRNA levels are controlled by metabolites of the arachidonic acid pathway.

Arachidonic Acids↗
PubMed1990

Transcriptional and post-transcriptional regulation of c-jun expression during monocytic differentiation of human myeloid leukemic cells.

AP-1, the polypeptide product of c-jun, recognizes and binds to specific DNA sequences and stimulates transcription of genes responsive to certain growth factors and phorbol esters such as 12-O-tetradecanoylphorbol-13-acetate (TPA). We studied the effects of TPA on the regulation of c-jun gene expression in HL-60 cells during monocytic differentiation. Low levels of c-jun transcripts were detectable in untreated HL-60 leukemic cells, increased significantly by 6 h, and reached near maximal levels by 24 h of exposure to 32 nM TPA. Similar kinetics of c-jun induction by TPA were observed in human U-937 and THP-1 monocytic leukemia cells. Similar findings were obtained with bryostatin 1 (10 nM), another activator of protein kinase C and inducer of monocytic differentiation. Furthermore, 1,25-dihydroxyvitamin D3 (0.5 microM), a structurally distinct agent which also induces HL-60 monocytic differentiation, increased c-jun expression. TPA treatment of HL-60 cells in the presence of cycloheximide was associated with superinduction of c-jun transcripts. Run-on analysis demonstrated detectable levels of c-jun gene transcription in untreated HL-60 cells, and that exposure to TPA increases this rate 3.3-fold. Treatment of HL-60 cells with both TPA and cycloheximide had no effect on the rates of c-jun transcription. The half-life of c-jun RNA as determined by treating HL-60 cells with TPA and actinomycin D was 30 min. In contrast, the half-life of c-jun RNA in TPA-treated HL-60 cells exposed to cycloheximide and actinomycin D was greater than 2 h. These findings suggested that the increase in c-jun RNA observed during TPA-induced monocytic differentiation is mediated by both transcriptional and post-transcriptional mechanisms.

Calcitriol↗
PubMed1990

Fatal disseminated mycobacterial infection following intravesical bacillus Calmette-Guerin.

We describe a fatal case of disseminated mycobacteriosis after intravesical bacillus Calmette-Guerin immunotherapy. We summarize the prior safety record of this therapeutic modality, discuss local and systemic pathophysiological mechanisms by which dissemination might have occurred, and review the reported clinical experience with antituberculous chemotherapy for significant bacillus Calmette-Guerin infection. Finally, we offer suggestions for prophylaxis of certain patients with a history of exposure to intravesical bacillus Calmette-Guerin.

Administration, Intravesical↗
PubMed1990

The unique aspects of acute promyelocytic leukemia.

Acute promyelocytic leukemia (APL) accounts for approximately 10% of cases of acute myeloid leukemia (AML). Distinctive features of this disorder at the time of diagnosis include leukopenia coexisting with a marrow replaced with granulated dysplastic promyelocytes, disseminated intravascular coagulopathy, lack of Ia (HLA-DR) antigen expression, and translocation between the long arms of chromosomes 15 and 17 (t[15;17]). Heparin is widely but not universally used to interfere with the coagulopathy during the initial phases of treatment. Serial bone marrow examinations during the induction period demonstrate the achievement of remission despite the persistence of malignant-appearing promyelocytes. Patients with APL are generally younger than those with other subtypes of AML, have a 70% to 80% likelihood of entering remission, and are thought to have a more favorable prognosis than other individuals with AML. Remission may be achieved with a conventional anthracycline-cytarabine combination, anthracycline alone, or, apparently, all-trans retinoic acid. Genes potentially important in myeloid differentiation such as granulocyte colony-stimulating factor (G-CSF) and myeloperoxidase are located close to the breakpoint in the t(15;17) but have not been conclusively shown to be rearranged in the translocation. A better understanding of the unique aspects of APL may well shed light on the pathogenetic processes of AML.

Blood Coagulation↗
PubMed1990

Prolymphocytic leukemia.

PLL is an unusual clinical and morphologic variant of CLL which, in the more common B cell version, represents malignant transformation of a B lymphocyte at an intermediate stage of development. The immunophenotype of PLL cells, characterized by heavy cell surface staining for IgM and/or IgD and loss of mouse red blood cell receptors, suggests derivation from a slightly more mature cell than the one that gives rise to typical CLL. In patients with PLL prolymphocytic invasion accounts for massive splenomegaly and white counts of well over 100,000 per mm3 with minimal lymphadenopathy. Prolymphocytes are large cells with relatively open chromatin and prominent nucleoli. Extra material on the long arm of chromosome 14 is the most common cytogenetic abnormality. The clinical course of patients with PLL is aggressive, with median survivals usually of all stages. Combination chemotherapy regimens typically reserved for those with an unfavorable prognosis for non-Hodgkin's lymphomas probably are more effective in the treatment of patients with PLL than are the less myelosuppressive oral regimens used in CLL.

Antineoplastic Combined Chemotherapy Protocols↗
PubMed1990

A phase I study of intermittent continuous infusion high dose cytosine arabinoside for acute leukemia.

We previously administered ara-C at a dose rate of 250 mg/m2/hr for 36-72 hr to patients with leukemia. Gastrointestinal toxicity was dose-limiting. This regimen was modified to an every other day schedule, administering 24-hr periods of high dose continuous infusion ara-C, each followed by a 24-hr rest period. Sixteen patients with relapsed/refractory acute myeloid leukemia (AML) (N = 4), secondary AML (N = 2), relapsed/refractory acute lymphoblastic leukemia (N = 7), or CML in blast crisis (N = 3) received this regimen of three 24-hr infusions with two intercurrent 24-hr rest periods. Grade 3 gastrointestinal toxicity was encountered in 57% of the courses, and hypoplasia was achieved in all patients. Three of the patients died while hypoplastic, two with septicemia and another with intracranial hemorrhage. There were five responding patients (2 CRs, 3 PRs). Median steady-state plasma ara-C levels were 24 microM, 22 microM, and 20 microM during the first, second, and third 24-hr infusions, respectively. Ara-C levels ranged from 4-118 microM during the infusions and were always below 4.5 microM during the rest periods. A significant level of ara-C incorporation into DNA was detected in each of the five patients studied, thus demonstrating that (ara-C)DNA formation is detectable in blasts from patients receiving high dose continuous infusion ara-C therapy. These findings suggest that alternate day continuous infusion ara-C may be useful in the treatment of acute leukemia and CML in blast crisis.

Adult↗
PubMed1988

Bryostatin 1 activates protein kinase C and induces monocytic differentiation of HL-60 cells.

Phorbol esters induce the human HL-60 promyelocytic cell line to differentiate along a monocytic pathway. This induction of differentiation may involve phorbol ester-induced activation of the phospholipid- and calcium-dependent protein kinase C. Bryostatin 1, a macrocyclic lactone, has been shown to compete with phorbol esters for binding to protein kinase C. We have confirmed that bryostatin 1 translocates activity of protein kinase C from the cytosolic to membrane fractions of HL-60 cells. The present results also demonstrate that bryostatin 1 (10 nmol/L) induces monocytic differentiation of HL-60 cells as determined by adherence, growth inhibition, appearance of monocyte cell surface antigens, and alpha-naphthyl acetate esterase staining. Furthermore, bryostatin 1 (10 nmol/L) downregulated c-myc expression and induced c-fos, c-fms, and tumor necrosis factor transcripts. These changes in gene expression induced by bryostatin 1 are similar to those associated with phorbol ester-induced monocytic differentiation of HL-60 cells. In contrast, exposure to a higher concentration of bryostatin 1 (100 nmol/L) had less of an effect on growth inhibition of HL-60 cells and changes in gene expression. Moreover, 100 nmol/L bryostatin 1 antagonized the cytostatic effects and adherence induced by phorbol esters. Our results thus suggest that bryostatin 1 activates HL-60 cell protein kinase C and that this effect is associated with induction of monocytic differentiation.

Bryostatins↗
PubMed1988

Magnetic resonance imaging, computed tomography, and radionuclide scintigraphy in detection of liver metastases.

A series of 100 patients with suspected hepatic metastases was studied with magnetic resonance (MR), unenhanced computed tomography (CT), and radionuclide (RN) scintigraphy. Each set of images was read by three clinicians using a five-point scale to allow receiver operating characteristic (ROC) analysis using truth data derived from clinical review. Performance was measured by the areas under the ROC curves (0.940 +/- .018 for MR, 0.951 O +/- .013 for CT and 0.943 +/- .013 for RN) which were statistically not significantly different. We conclude that at their present level of development these three diagnostic examinations have equivalent performance and that MR is not superior in the detection of hepatic metastases.

Evaluation Studies as Topic↗
PubMed1988

MRI of periprostatic venous plexus in staging of early prostatic carcinoma.

The periprostatic venous plexus can be observed as a bright rim in coronal magnetic resonance (MR) images obtained by spin-echo (SE) 2060/60 technique. A carcinoma of the prostate which penetrates through the capsule into the periprostatic tissues interrupts or obliterates this rim, whereas an intact rim indicates that the tumor is confined within the prostatic capsule. One hundred patients with proven prostatic carcinoma were prospectively imaged by MR to detect periprostatic involvement. The results were compared with those obtained by cystoscopy and digital rectal examination under general anesthesia. The imaging and clinical methods agreed with each other in 76% of the patients.

Adult↗
PubMed1988

Phospholipase C activates protein kinase C and induces monocytic differentiation of HL-60 cells.

Phospholipase C (PLC)-mediated hydrolysis of membrane phospholipids results in the production of diacylglycerol, inositol phosphates, and choline metabolites. Inositol triphosphate increases calcium levels, while diacylglycerol activates protein kinase C. The present studies demonstrate that exogenous PLC generates inositol phosphates, releases choline metabolites, and activates protein kinase C in human HL-60 promyelocytic leukemia cells. PLC also induced monocytic differentiation of HL-60 cells as manifested by adherence, growth inhibition, and appearance of monocytic cell surface antigens. Furthermore, PLC treatment decreased c-myc mRNA levels and induced c-fos, c-fms, and tumor necrosis factor transcripts. The changes in gene expression induced by PLC are similar to those previously shown to be associated with phorbol ester-induced monocytic differentiation of HL-60 cells. Our results thus demonstrate that exogenous PLC activates HL-60 cell protein kinase C and that this effect is associated with induction of monocytic differentiation. PLC may therefore play a role in transducing signals from physiological inducers of monocytic differentiation.

Cell Differentiation↗
PubMed1988

Complete remission in acute promyelocytic leukemia despite persistence of abnormal bone marrow promyelocytes during induction therapy: experience in 34 patients.

Thirty-four patients with acute promyelocytic leukemia (APL) (median age 37 years, range 20 to 69 years) received induction treatment between 1974 and 1985 with cytosine arabinoside (ara-C) and an anthracycline. Bone marrow hypercellularity was present at the time of diagnosis in all patients, although the median peripheral leukocyte count was 2,600/microL. A second course of induction therapy consisting of further ara-C and anthracycline was initiated 15 days after the start of treatment if bone marrow hypocellularity could not be documented. Karyotypic analysis of bone marrow blasts was performed on 15 of 34 patients; 11 of 15 had abnormalities in chromosomes 15 and/or 17. Twenty-nine of 34 (85%) patients had laboratory evidence of disseminated intravascular coagulopathy. Of the 29 patients surviving 14 days, 24 (83%) received a second course of induction therapy. Complete remission was achieved in 25 of 34 (74%) patients, with four of 25 (16%) requiring one course of induction chemotherapy and 21 of 25 (84%) receiving two courses. Bone marrow specimens obtained 15 days after the start of therapy from the 25 patients who eventually attained complete remission showed the continued presence of dysplastic promyelocytes in 21 cases; three specimens were technically inadequate and only one was truly devoid of promyelocytes. Seventeen of 25 (68%) patients still had persistence of abnormal bone marrow promyelocytes seven or more days after the second course of therapy. Patients in complete remission received various forms of postremission therapy. Ten of the 25 (40%) completely responding patients remain alive in continuous complete remission. Neither the absence of bone marrow hypocellularity nor the persistence of dysplastic promyelocytes during induction exerted any influence on the probability for survival. These findings confirm and extend prior reports that complete remission in APL, in contrast to other subtypes of acute nonlymphocytic leukemia (ANLL), can frequently be achieved without bone marrow aplasia. Whether this observation signifies that complete remission in APL is due to leukemic cell differentiation or selective cytotoxicity is unknown. The absence of therapy-induced bone marrow hypoplasia in APL is not an absolute indication of induction failure or a poor ultimate prognosis.

Acute Disease↗
PubMed1987

Is heparin administration necessary during induction chemotherapy for patients with acute promyelocytic leukemia?

The role of heparin in the treatment of the disseminated intravascular coagulation (DIC) associated with acute promyelocytic leukemia (APL) remains unclear. Between 1974 and 1985, we treated 27 patients with APL using four different chemotherapeutic regimens; 23/27 (85%) had evidence of DIC either at presentation or following the initiation of induction chemotherapy. The coagulopathy was treated primarily with fresh frozen plasma and platelet transfusions; only 2/27 (7%) patients received heparin. Twenty of 27 patients (74%) entered complete remission. Major bleeding or thrombotic complications occurred in 5/27 patients (19%), but 2 of these 5 patients presented after hemorrhage had already occurred. None of the 5 patients with bleeding or thrombosis entered complete remission. All of the hemorrhagic complications due to DIC in our study occurred before 1979, which may reflect changes in the management of leukemic patients. This observation emphasizes the risks inherent in the use of historical controls in this population. In conclusion the DIC associated with APL can be successfully treated with intensive blood product support without the use of heparin.

Adult↗
PubMed1986

The treatment of myelodysplastic syndromes.

The available data fail to support a standard therapy for MDS. Any therapy should therefore, include participation in a well designed clinical trial. The MDS include patients with a variety of prognoses. Since most studies show that death from infection and bleeding are more likely than progression to frank leukaemia, attention to supportive care is crucial for all patients with MDS. Some patients with MDS may be successfully supported with transfusions and observation for prolonged periods. Patients with significant comorbid disease or patients without increased marrow myeloblasts are good candidates for this conservative approach. Conversely, young patients have a better likelihood of benefit from aggressive therapy, and intensive chemotherapy or allogenic bone marrow transplantation should be considered. Patients with preleukaemia related to prior cytotoxic therapy are another poor prognosis group for whom aggressive therapy may be the best alternative. Therapy with low-dose ara-C or other differentiating agents should be considered investigational and unproven until comparative trials can demonstrate a definitive survival advantage. In addition to comparative trials, innovative clinical studies are needed to address differentiation as an in vivo mechanism of action and its importance in MDS therapy.

Adult↗