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Biomedical subjects

R L Capizzi

Publications and source records attributed to R L Capizzi.

At least 55 records · Page 3Linked to original sources
PubMed1990

Ether-linked phosphoglyceride content of human leukemia cells.

The glycerolipids of most cells are characterized by a specific proportion of ether linkages at the sn-1 position of the glycerol backbone. A number of tumors are known to have altered concentrations of ether-linked lipids compared to normal tissues. However, no through examination of the ether-lipid content of human leukemia cells has been reported despite the importance of these lipids in normal leukocyte function. In the present study samples were obtained from adults with acute myelogenous leukemia (AML), chronic granulocytic leukemia in blast crisis, and acute lymphocytic leukemia and from healthy human donors. The cellular lipids were extracted, the individual phospholipid classes were isolated, lipid phosphorus content was determined, and the lipids were converted to diglyceride benzoate derivatives for separation and quantitation of the subclasses by high performance liquid chromatography. The data indicate that all the leukemic cells analyzed have an altered phospholipid composition compared to their respective normal leukocytes. Furthermore, among the AML patients both the percentage of the choline-containing phosphoglyceride fraction (PC) which is alkyl linked and the nmoles alkyl-PC/10(6) cells differ significantly by FAB subtype. A positive correlation between the levels of alkyl-PC and the degree of cellular differentiation is observed. Although no differences are observed between chronic granulocytic leukemia in blast crisis and AML lipids, the leukemic cells contain dramatically lower levels of alkyl-linked PC than do normal polymorphonuclear leukocytes. In contrast, no differences are observed between the alkyl-PC content of normal and leukemic lymphocytes. In light of the relations among ether-lipids, protein kinase C, and cell differentiation, these data suggest the ether-linked lipids are important in myeloid cell function and differentiation.

Alkylation↗
PubMed1990

Bromodeoxyuridine incorporation into DNA of human leukemia cells is not concentration dependent.

Leukemia blasts isolated from bone marrow aspirates of 44 adults with acute leukemia were incubated for 1 h with 0.008-32 microM bromodeoxyuridine (Brd-Urd). After dual labeling with monoclonal anti-BrdUrd antibodies and propidium iodide, the cells were analyzed by flow cytometry. Percent labeled cells and intensity of labeling were similar over concentrations of BrdUrd ranging from 0.8-32 microM--a 40-fold range. Therefore, despite potential interpatient variability in nucleoside pharmacokinetics, commonly used doses of BrdUrd which are intended to achieve steady-state plasma concentrations in the 8.0 microM range can be expected to provide a reliable estimate of the S-phase fraction.

Antibodies, Monoclonal↗
PubMed1990

A phase II trial of PEG-L-asparaginase in the treatment of non-Hodgkins lymphoma.

A polyethylene glycol conjugate of L-asparaginase (PEGLA) was administered to 21 patients with refractory non-Hodgkin's lymphoma. The dose given was 2,000 mu/m2 intramuscularly every 2 weeks. Eligibility required at least one prior trial of chemotherapy and ambulatory performance status. At entry, all patients had measurable lesions and documented disease progression. The median age of the patients was 61 years; 18 (86%) were ambulatory with minimal symptoms, 12 patients (57%) had 3 or more prior regimens, and 13 (62%) had stage IV disease. Histologic subtype was low grade in 11 patients (52%), intermediate in 7 (33%), high grade in 2 (10%) and unclassifiable in one (5%). There were two partial responses (11%) noted (95% confidence interval of response of 1-30%). Eleven patients (52%) were removed from study due to disease progression. Nine patients (43%), required removal for toxicity (7 for protracted nausea and vomiting and 2 for confusion). One patient died of sepsis while on study but this was not considered drug related. Almost one third of patients complained of fatigue or loss of appetite. Nausea and vomiting occurred in approximately half the patients and was moderate to severe in 9. Diarrhea and abdominal pain were also noted in one-third of those treated. Changes in the partial thromboplastin time and fibrinogen were noted in most patients but resulted in no bleeding complications. In this trial, PEGLA displayed modest activity in a heterogenous group of patients with progressive non-Hodgkin's lymphoma.

Adult↗
PubMed1990

The effect of ara-C-induced inhibition of DNA synthesis on its cellular pharmacology.

The cytotoxicity of ara-C is believed to result from incorporation of ara-CTP into DNA and inhibition of DNA synthesis. Since complete inhibition of DNA synthesis would prevent further incorporation of ara-CTP, ara-C may have a self-limiting effect on its own cytotoxicity, particularly at the high concentrations typical of high-dose ara-C clinical protocols. In this study, the incorporation of [3H]-dThd and [3H]-ara-C into DNA were compared. Within 1 h of exposure of L5178Y cells to ara-C, the rate of [3H]-dThd incorporation into the acid-insoluble fraction was reduced by 98%. Despite this nearly complete block in [3H]-dThd incorporation, DNA synthesis was not completely inhibited since [3H]-ara-C continued to be incorporated for up to 6 h, although a plateau in ara-CDNA synthesis was observed between 2 and 3 h exposure when ara-CTP levels were maximal. The effect of ara-C on [3H]-dThd incorporation into DNA was due in part to an indirect effect of ara-C on the metabolism of intracellular [3H]-dThd to [3H]-dTTP. Within 30 min exposure to 10 microM ara-C, the rate of cellular [3H]-dTTP synthesis was slowed to only 15% of the control rate. This was not due to inhibition of [3H]-dThd transport, since the intracellular and extracellular concentrations of the nucleoside were equal. The effect of ara-C on [3H]-dTTP synthesis resulted from significant changes in deoxynucleoside 5'-triphosphate (dNTP) pools. dTTP, dATP, and dGTP levels were increased, whereas the dCTP concentration was decreased. When dThd kinase from L5178Y cells was assayed with increased dTTP levels induced by ara-C vs the dTTP level in control cells, its activity was reduced by 72%. Thus, the [3H]-dThd incorporation experiment overestimated the extent of inhibition of DNA synthesis by ara-C due to increased feedback inhibition of dThd kinase and increased competition for DNA polymerase between the elevated unlabeled dTTP pool and the decreased levels of [3H]-dTTP. In vitro assay of DNA polymerase in the presence of the ara-CTP concentration achieved after 0.5 or 3 h exposure to 10 microM ara-C (60 microM and 200 microM, respectively), plus the mixture of dNTPs found intracellularly at these times, resulted in 57% and 80% inhibition of the polymerase, respectively. This inhibition may account for the plateau in the accumulation of ara-CDNA that was observed at 3 h and suggests that ara-C incorporation may be self-limiting at high cellular concentrations of ara-CTP.(ABSTRACT TRUNCATED AT 400 WORDS)

Animals↗
PubMed1990

Enhanced retention of cytosine arabinoside and its metabolites and synergistic cytotoxicity by sequential treatment with dipyridamole in L5178Y leukemia.

Sequential treatment of murine leukemia L5178Y with cytosine arabinoside (ara-C) followed by dipyridamole (DP) resulted in synergistic cytotoxicity. Viability of cells exposed to 1 microM ara-C for 4 h was 88% of control values, but if DP was included in the cloning medium, cell viability was reduced to only 30%. When cells exposed to 1 microM ara-C were resuspended in ara-C-free medium containing 10 microM DP, intracellular ara-C and its metabolites were retained for a significantly longer period than when cells were resuspended in drug-free medium. At 4 h after resuspension in ara-C-free medium, total intracellular [3H] was 1.9 pmol/10(6) cells in control cells but amounted to 6.2 pmol/10(6) cells in DP-treated cells. Unchanged ara-C was 5.5-fold higher in the DP-treated cells. Presumably because of its effect on the concentration of intracellular ara-C, DP increased the half-life for ara-CTP from 97 to 250 min. Ara-CDP-choline declined with a half-life of 76 min on the transfer of cells to control medium, but levels of this metabolite remained constant or increased slightly in cells transferred to medium containing DP. After 4 h in ara-C-free medium with DP, [3H]-ara-C incorporated into the acid-insoluble fraction was 140% of the level attained when cells were transferred to control medium. The increased levels of ara-C metabolites presumably represent the basis for the enhancement of ara-C cytotoxicity by sequential DP treatment.

Animals↗
PubMed1990

Interaction of granulocytopenia and construction activity as risk factors for nosocomial invasive filamentous fungal disease in patients with hematologic disorders.

A clinicoepidemiologic study was undertaken to investigate an apparent increase in frequency of nosocomial invasive filamentous fungal disease (NIFFD) in adult patients with acute leukemia hospitalized during a period of hospital construction, and to determine if a relationship existed between the construction activity and the acquisition of NIFFD. The first study goal, to determine the incidence of NIFFD before and during construction, was approached by calculation of incidence rates of NIFFD in patients with acute leukemia, comparing 1982 and 1983 (a baseline period free of construction) to 1986 (a year when construction activity was at its peak). The second study goal, to identify risk factors for the development of NIFFD, was accomplished by reviewing the autopsy records of all patients with underlying hematologic disorders accompanied by granulocytopenia who died in our hospital from 1982 through 1986. Patients with and without autopsy evidence of NIFFD were then compared by univariate and multivariate (logistic regression) analysis to identify potential risk factors for the acquisition of NIFFD. The incidence of NIFFD in patients with acute leukemia hospitalized during the period of hospital construction was significantly increased when compared to a baseline period without construction (11 per 139 versus 4 per 333, p less than .001). Review of all granulocytopenic patients autopsied over the five-year interval 1982 through 1986 revealed duration of granulocytopenia and hospitalization during construction to be risk factors for NIFFD by univariate analysis (p less than .005). Logistic regression showed duration of granulocytopenia to be highly significant independent risk factor (p less than .01) and construction activity to be a probable independent risk factor (p = .09).(ABSTRACT TRUNCATED AT 250 WORDS)

Cross Infection↗
PubMed1990

High- versus standard-dose megestrol acetate in women with advanced breast cancer: a phase III trial of the Piedmont Oncology Association.

One hundred seventy-two patients with advanced breast cancer were randomized to receive oral standard-dose megestrol acetate (MA), 160 mg/d or high-dose MA, 800 mg/d. All but two patients had one prior trial of tamoxifen therapy for either metastatic disease (74%) or as adjuvant treatment (26%). Pretreatment characteristics were similar for both arms. High-dose MA resulted in a superior complete plus partial response rate (27% v 10%, P = .005), time to treatment failure (median, 8.0 v 3.2 months, P = .019), and survival (median, 22.4 v 16.5 months, P = .04) when compared with standard-dose therapy. These differences remained significant after adjustment for other covariates. Thirty-four patients were given high-dose MA after failure of standard-dose MA treatment, and none responded. Weight gain was the most distressing side effect, with 13% of standard-dose and 43% of high-dose patients gaining more than 20 lbs. Four major cardiovascular events occurred in patients receiving high-dose treatment and one in patients given standard doses. Other toxicity was modest. High-dose MA may represent a significant improvement in secondary endocrine therapy for advanced breast cancer patients refractory to initial endocrine treatment, but its use on a regular basis should be reserved until these results are confirmed by other clinical trials.

Adult↗
PubMed1990

Correlation of the proliferative index of residual leukemia with outcome in patients treated with sequential high dose ara-C and asparaginase.

Therapy of acute myelogenous leukemia (AML) with sequential high-dose ara-C and asparaginase (HiDAC----ASNase) on a day 1 and 8 schedule was designed to exploit potential recruitment of residual leukemia cells following initial cytoreduction from day 1 treatment. DNA flow cytometry was used to evaluate the proliferative index (%S + G2M) of bone marrow leukemia cells from pretreatment and day 8 marrow samples. The proliferative index on day 1, day 8, and incremental change (day 8 minus day 1) were analyzed for their correlation with bone marrow aplasia on day 15 and with the attainment of subsequent complete remission. Pretreatment (day 1) and the change in proliferative index did not correlate (p greater than 0.10) with day 15 marrow aplasia or with clinical outcome. However, the magnitude of the day 8 proliferative index did relate to the attainment of bone marrow aplasia on day 15 (p = 0.05) and the attainment of complete remission (p = 0.002). Recruitment of residual leukemia cells into the proliferative phases of the cell cycle may contribute to the unique efficacy of the day 1 and 8 schedule of HIDAC----ASNase. Additionally, the cytokinetics of residual leukemia after initial chemotherapy may be predictive of outcome and could be useful as a marker for the design of optimal therapeutic regimens.

Adolescent↗
PubMed1989

Determination of 3H-labelled cytosine arabinoside and eight metabolites in cell extracts by high-performance liquid chromatography and scintillation spectrometry.

We have developed a method for the separation and quantitation of radiolabeled cytosine arabinoside and its eight metabolites in cell extracts by anion-exchange gradient high-performance liquid chromatography. Baseline separation of cytosine arabinoside and uracil arabinoside and their respective 5'-mono-, di- and triphosphates, as well as cytosine arabinoside diphosphocholine was obtained with the shortest interval between peaks being 3 min. This degree of separation was found to be essential for quantitation of 3H-labeled metabolites by scintillation counting of 1-min fractions. Application of this procedure to the quantitation of [3H] cytosine arabinoside and its metabolites from HL60 human leukemia cells is demonstrated.

Arabinofuranosyluracil↗
PubMed1989

Modulation of the metabolism and pharmacokinetics of 1-beta-D-arabinofuranosylcytosine by 1-beta-D-arabinofuranosyluracil in leukemic mice.

The interaction between high concentrations of 1-beta-D-arabinofuranosyluracil (HiCAU) and 1-beta-D-arabinofuranosylcytosine (ara-C) was investigated in vivo with emphasis on cell kinetics, pharmacokinetics, and drug metabolism. Mice bearing L5178Y leukemia were given a 48-h s.c. infusion of high-dose ara-U (HiDAU) to achieve a plasma level of 0.5 to 1 mM. A total dose of 7.35 g/kg/day for 2 days was nontoxic; the mean survival of control (saline treated) leukemic mice was 12.2 +/- 1.8 days and 11.7 +/- 2.0 days for the HiDAU-treated leukemic mice. Using flow cytometry, cell cycle progression of L5178Y ascites cells was monitored during HiDAU infusion. At 48 h, the proliferative index (PI) percentage of the leukemic cells is significantly different (P less than 0.001) in HiDAU-treated leukemic mice (mean = 50.8) versus control (mean = 45.6). A higher PI percentage is associated with accumulation of cells in S phase. This effect was highly variable in the ara-U-treated mice, and the ara-U "perturbed" group was defined as those mice whose cells had an increase in the PI to greater than or equal to 50%. The higher PI percentage in HiDAU-treated mice correlated with HiCAU in ascites fluid, leukemic cells, and kidney of perturbed mice. HiCAU in the "ara-U-perturbed" group altered the plasma pharmacokinetics of high-dose ara-C (HiDAC, 1 g/kg), increased the cellular metabolism of ara-C to 1-beta-D-arabinofuranosylcytidine triphosphate (ara-CTP) (3-fold), and increased ara-C-DNA synthesis (3-fold). In mice bearing the L5178Y leukemia, a 48-h infusion of ara-U followed by a 24-h s.c. infusion of 40 mg/kg resulted in a 260% increase in life span and seven 90-day survivors among 16 treated mice. In contrast, ara-U or ara-C alone had a negligible therapeutic effect. ara-U-induced alterations in the systemic pharmacokinetics of ara-C are the result of inhibition of cytidine deaminase activity by HiCAU in liver and kidneys. This results in a decrease in ara-C catabolism and prolongs the plasma half-life of ara-C. The dual alteration of the pharmacokinetics of ara-C and cytokinetics of the leukemia cells by HiCAU results in enhanced survival of leukemic mice. These results may help explain the clinical utility of HiDAC treatment programs for patients with acute leukemia.

Animals↗
PubMed1989

Mitoxantrone and high-dose ara-C in refractory malignancies: a phase I trial.

On the basis of in vitro studies demonstrating marked synergy between mitoxantrone and high-dose cytosine arabinoside (ara-C) (HiDAC) against L5178Y murine leukemia and clinical studies showing usefulness of the combination in patients with refractory acute myeloid leukemia, a phase I study was initiated to find tolerable doses for use in patients with refractory solid tumors. Initial dose levels were mitoxantrone 2 mg/m2 infused over 30 minutes, followed by high-dose ara-C 750 mg/m2 infused over 3 hours repeated once at 24 hours (total dose 4 mg/m2 mitoxantrone and 1,500 mg/m2 HiDAC per 2-day course), with planned subsequent escalation of mitoxantrone. Moderate-to-severe myelosuppression, however, required sequential dose reduction of both agents. Nonhematologic toxicity was restricted to manageable nausea and vomiting in one-half the patients and a single episode of transient delirium of uncertain etiology. No responses were observed in 23 heavily pretreated patients with a wide variety of malignancies. On the basis of this study, doses of 187-375 mg/m2 ara-C given every 24 hours for two doses following mitoxantrone 1 mg/m2 every 24 hours for two doses would be tolerated by most patients with subsequent dose escalation in some as allowed by myelosuppression.

Adult↗
PubMed1989

The safety of dental extractions in patients with hematologic malignancies.

Dental disorders have been recognized as major sources of infection in patients with hematologic malignancies (HM). Management of severe dental infections usually includes dental extractions (DE), but the safety of extractions in patients with HM who are at risk for bleeding, sepsis, and poor wound healing has not been well established. In conjunction with an aggressive program of dental care, 142 DE were performed in 26 patients with acute leukemia, myelodysplastic syndromes, and myeloproliferative disorders. Granulocytopenia (less than 1,000 granulocytes/microL) was present during or within ten days following surgery in 14 patients. In these 14 patients (101 DE), the mean granulocyte count was less than 450/microL, with a median duration of granulocytopenia following surgery of 32 days (range, four to 169 days). Thrombocytopenia (less than 100,000 platelets/microL) occurred during or within two days following surgery in 13 patients (80 DE), with a mean platelet count of 63,500/microL. Transfusions were given for platelet counts less than 50,000/microL. All DE were performed without significant complications. Bleeding was minor to moderate and easily controlled with local measures; no patient required transfusion due to hemorrhage. Average maximum temperature 24 hours after DE was 37.7 degrees C. No episodes of bacteremia were documented within ten days of DE. Minor delay in wound healing was observed in two patients. We conclude that DE can be safely performed in patients with HM in combination with aggressive supportive care.

Agranulocytosis↗
PubMed1989

Chemoinfusion of the hepatic artery for metastases to the liver.

During a five year period, 69 patients were treated for carcinoma of the liver (seven primary tumors and 62 metastatic tumors) with 5-fluorodeoxyuridine (5-FUDR) administered through a hepatic artery (n = 62) or portal vein (n = 3) implantable infusion pump. Ten patients proved to have previously unsuspected extrahepatic nodal metastases at laparotomy for pump insertion. 5-FUDR was given in 14 day cycles for three months. At the end of that period and at three month intervals thereafter (mean follow-up time of 18 months, a range of one to 60 months), patients were evaluated with roentgenograms of the chest, liver function tests, carcinoembryonic antigen levels, radionuclide scans and computed tomography. Thirty-five patients had a partial response, nine had stabilization of the disease and 25 had progression of the disease (five during therapy, who were given mitomycin C). Median regression was 6.8 months (a range of three to 18 months). Six of the 35 partial responders, three of the nine patients with stabilization and ten of the 25 patients with progression had extrahepatic visceral disease. Survival time averaged 18.4 months (a range of five to 60 months) for the partial responders, 12.6 months (a range of two to 40 months) for patients with stabilization and seven months (a range of one to 17 months) for those with progression of the disease.

Adult↗
PubMed1989

Low-dose ara-C therapy for acute myelogenous leukemia in elderly patients.

Forty-four evaluable patients with untreated acute myelogenous leukemia received twice-daily subcutaneous injections of low-dose ara-C (10 mg/m2) for less than or equal to 42 days. The median age was 72 years (range 53-87); 42 of 44 patients were greater than or equal to age 60. Ten patients (23%) had complete responses with a median duration of 9.9 months. Median survival was 3 months (range 0.6-31.2+) for all patients, and 19.5 (range 7.9-31.2+) for patients who attained complete responses. Cytoreduction occurred slowly with low-dose ara-C and five of ten patients who achieved complete remission did not develop marrow aplasia. Toxicity was predominantly related to infections associated with granulocytopenia. Nonhematologic toxicity was limited. Low-dose ara-C as used in this trial results in a complete response rate and a duration of response similar to those achieved with other treatments in elderly patients, but with reduced toxicity.

Aged↗
PubMed1988

Proliferation-dependent cytotoxicity of methotrexate in murine L5178Y leukemia.

The basis for the proliferation-dependent cytotoxicity of methotrexate has been investigated in mice bearing the L5178Y ascites leukemia. Methotrexate at 60 mg/kg i.p. reduced the viability of logarithmically growing ascites cells (55% active S phase cells) to 28% of control, whereas the viability of the slowly growing cells (18% active S phase) was decreased to only 59% of control. Log phase tumor cells accumulated 8-fold higher levels of methotrexate polyglutamates compared to cells that had approached the stationary phase. However, no differences between log phase and slowly growing tumor cells were observed in the cellular levels of unmetabolized methotrexate. Intestinal mucosa and bone marrow from non-tumor-bearing mice resembled slowly growing tumor cells and had markedly lower levels of methotrexate polyglutamates than logarithmically growing cells. The greater accumulation of methotrexate polyglutamates in the logarithmically growing tumor cells was consistent with an increased synthesis of methotrexate polyglutamates in these cells. The enhanced methotrexate polyglutamylation in log phase versus slowly growing cells was not related to changes in the rates of either cellular methotrexate transport, transmembrane efflux of methotrexate, or hydrolysis of methotrexate polyglutamates. Thymidylate synthase activity measured in situ and in extracts from log phase cells was 4- and 2-fold higher, respectively, than in the more slowly growing cells. Methotrexate produced a 2.4-fold greater depletion of poly-gamma-glutamyl derivatives of 5,10-methylenetetrahydropteroylglutamate in log phase cells compared to slowly growing cells, and this was a function of both the increased methotrexate polyglutamate accumulation and thymidylate synthase activity in the rapidly proliferating cells. These results provide further evidence that the selectivity of methotrexate for tumors with a high growth fraction is a consequence of the rapid rates of both cellular methotrexate polyglutamate synthesis and oxidation of 5,10-methylenetetrahydropteroyl polyglutamates by thymidylate synthase.

Animals↗