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Biomedical subjects

B L Powell

Publications and source records attributed to B L Powell.

At least 73 records · Page 4Linked to original sources
PubMed1987

Sequential high-dose ara-C and asparaginase versus high-dose ara-C alone in the treatment of patients with relapsed and refractory acute leukemias.

In consideration of the full spectrum of hematologic and nonhematologic toxicity juxtaposed to the response rates (Tables 2-5), it appears that for relapsed patients with AML, six to eight consecutive doses of HDara-C or four doses started on days 1 and 8 have the optimal therapeutic index. These regimens are associated with a 25% CR rate and have comparable tolerable and reversible toxicity spectra. An increase in the total number of doses to 12 does not appear to increase the remission frequency in relapsed patients but does decidedly increase the spectrum, frequency, and severity of toxic manifestations. Studies of important pharmacologic determinants such as membrane transport and cellular accumulation of ara-CTP suggest that a lower unit dose may be just as effective, an approach that could potentially lower the frequency and severity of toxicity. However, these concepts must be tested in suitably designed clinical trials. In contrast to the response rate noted in patients with relapsed AML, patients with refractory AML have a substantially lower CR rate (approximately 10%) when treated with HDara-C alone. These lower CR rates are comparable to those reported for other recently introduced new drugs such as m-AMSA and mitoxantrone. In this setting of primary refractory leukemia, multi-institutional and cooperative group trials of HD-ara-C----ASNase show a consistently higher response rate in the range of 30% to 50%. Why ASNase should especially contribute to this particular group is unknown at present. Studies show that the gene for asparagine synthetase is repressed in AML cells. It is speculated that in the initial leukemia cell population (as encountered in refractory AML), the gene for asparagine synthetase is repressed and hence, the leukemia is sensitive to ASNase. In contrast, in the relapsed patient with recurrent leukemia, the gene for asparagine synthetase may be derepressed and the leukemia would be ASNase-insensitive. The therapeutic index of HDara-C----ASNase is schedule dependent. In leukemic mice, pretreatment or concurrent administration of ASNase and HDara-C leads to antagonism of both the therapeutic and toxic effects of HDara-C. These effects are consistent with similar effects of other protein synthesis inhibitors on ara-C toxicity.(ABSTRACT TRUNCATED AT 400 WORDS)

Acute Disease↗
PubMed1986

Ara-C syndrome during low-dose continuous infusion therapy.

Four patients with acute nonlymphocytic leukemia developed one or more components of the "ara-C syndrome" including fever, peritonitis, pericarditis, and a maculopapular rash during therapy with continuous infusions of low-dose (20 mg/m2/d) cytosine arabinoside (ara-C). These complications, described with standard and high doses of ara-C, have not been previously noted with low-dose regimens.

Aged↗
PubMed1986

Sequential hemibody irradiation integrated into a chemotherapy-local radiotherapy program for limited disease small cell lung cancer.

Twenty-four patients with limited disease small cell lung cancer (SCLC) were treated with sequential hemibody irradiation (SHB) integrated into a conventional chemotherapy-local radiotherapy (LRT) program. Among 23 evaluable patients, 12 (52%) attained a complete response (CR) and 8 (35%) attained a partial response for an overall major response rate of 87%. The median time since study entry is 29 months. Durations of response are 9.9 months for all patients and 16.5 months for patients who achieved a CR. The primary site was the predominant area of recurrence. The median survival is 13.2 months for all patients and 23.2 months for the 12 patients who attained a CR. Myelosuppression, especially thrombocytopenia, was the major toxicity. Acute radiation toxicities and subacute pneumonitis previously associated with hemibody radiotherapy were well controlled or prevented using the current dose, premedication, and shielding techniques. This integrated program of systemic therapies with SHB and combination chemotherapy plus LRT is feasible for limited disease SCLC; it may prolong survival in patients who attain a CR but compared to similar programs without hemibody irradiation, there was no improvement in overall response rate, response duration, or survival.

Adult↗
PubMed1986

Peripheral neuropathy after high-dose cytosine arabinoside, daunorubicin, and asparaginase consolidation for acute nonlymphocytic leukemia.

Two patients with acute nonlymphocytic leukemia (ANLL) developed peripheral motor and sensory neuropathies after consolidation chemotherapy with high-dose cytosine arabinoside (ara-C), daunorubicin, and asparaginase. Evidence for ara-C and daunorubicin-induced peripheral neuropathies is reported. Despite the frequent use of these agents, only two cases of peripheral neuropathy after systemic therapy have been previously described; neurotoxic effects may be potentiated and become clinically important when the three drugs are used in combination.

Acute Disease↗
PubMed1986

Altered oxidative product formation in neutrophils of patients recovering from therapy for acute leukemia.

During chemotherapy for acute leukemias, severe neutropenia allows acquisition of life-threatening infections that are difficult to clear with antibiotics alone. With return of myelopoiesis, even severe infections often improve dramatically. We have sequentially examined oxidative metabolic responses of polymorphonuclear leukocytes (PMNL) from 30 patients with acute leukemias before induction chemotherapy and after recovery of myelopoiesis (circulating PMNL greater than 500/microL). Maximal oxidative metabolic responses were quantitated by flow cytometric analysis of H2O2-dependent oxidation of intracellular 2',7'-dichlorofluorescin (DCFH) in individual PMNL after stimulation with phorbol myristate acetate (PMA). Resting PMNL oxidized a mean of 6.8 attomoles (amol) DCFH/cell/15 min, with no difference between normal or patients' PMNL. PMA-stimulated normal PMNL oxidized 183 +/- 35 amol/cell (mean +/- SD, n = 120). In patients' PMNL obtained before chemotherapy, the mean DCFH oxidation was not significantly different from controls (216 +/- 78 amol/cell). However, 11 of 22 samples revealed populations of granulocytes with increased (primed) oxidative responses; seven of these 11 patients had proven or suspected infection at presentation. At recovery from chemotherapy-induced neutropenia, PMNL from 19 of 21 patients possessed one or more significant subpopulations with primed oxidation in response to PMA. In these 19 patients, 61% +/- 8% of PMNL comprised primed populations that oxidized 503 +/- 46 amol/cell. Oxidative activity was most pronounced in patients with proven or clinically suspected infections (with 41% +/- 9% of PMNL oxidizing 615 +/- 79 amol/cell). However, oxidative responses to PMA were also significantly increased in recovery PMNL from ten patients without clinical or laboratory evidence of active infection (79% +/- 11% of PMNL primed to oxidize 402 +/- 29 amol/cell). The peak responses of the primed subpopulations were short-lived and generally lasted three days or less, although oxidative responses remained elevated above normal for a week or more. All of the patients with increased PMNL responsiveness survived their hospitalization. In contrast, PMNL from four patients had a significant population (18% to 82% of cells) with reduced responsiveness. Two of these four patients (with 71% and 75% subnormal cells) died during this induction attempt; the third died during a second induction attempt; only one survived to discharge. The clinical significance of these phenomena is yet to be determined.(ABSTRACT TRUNCATED AT 400 WORDS)

Acute Disease↗
PubMed1985

Sequential hemibody and local irradiation with combination chemotherapy for small cell lung carcinoma: a preliminary analysis.

Sequential hemibody irradiation (SHB) was integrated with combination chemotherapy and local irradiation (LRT) in the induction and consolidation phases of a therapeutic protocol for small cell lung carcinoma (SCLC). Forty-one previously untreated patients were entered into this program. Among 38 evaluable patients (20 with limited disease [LD] and 18 with extensive disease [ED], the overall response rate was 63% (90% in LD and 33% in ED patients). The estimated overall survival is 8.1 months. The major toxicity has been myelosuppression--especially thrombocytopenia. The frequency of previously described "acute radiation syndromes" and radiation pneumonitis associated with hemibody irradiation have been substantially decreased at the current dosage with premedication and shielding techniques. The integration of SHB as a systemic therapy with combination chemotherapy and LRT is a feasible program for sequential administration of non-cross-resistant agents in SCLC and may be beneficial in patients with limited disease.

Adult↗
PubMed1985

Secondary malignancies of the penis and epididymis: a case report and review of the literature.

A patient with carcinoma of the colon developed metastases to the penis and right epididymis. These two organs are rare locations for metastases and the concurrent involvement of both sites has not been previously described. Our patient and the results of a literature review are presented. Two hundred eighteen cases of penile and 37 separate cases of epididymal metastases were identified. The genitourinary and gastrointestinal tracts were the predominant sites of the primary malignancies. Presenting symptoms, the interval between diagnoses of the primary and metastatic lesions, and the therapy of the penile/epididymal deposits varied greatly. Surgical excision is the major mode of therapy; radiotherapy, chemotherapy, or hormonal therapy may be beneficial in selected cases. Survival among these patients is poor due to the presence in most patients of widespread metastases in addition to their genital lesions. However, instances of prolonged survival are noted in both groups. Patient characteristics and possible mechanisms of metastatic spread to the genitals are discussed.

Adenocarcinoma↗
PubMed1984

Multiple myeloma.

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Acute Kidney Injury↗
PubMed1984

Focal neurologic signs associated with hyperkalemia.

A patient with end-stage renal disease had a flaccid hemiparesis in conjunction with severe hyperkalemia. The hemiparesis resolved with treatment of the hyperkalemia. The patient was later found to have extracranial vascular disease, and we propose that a severe metabolic abnormality associated with an area of relative cerebral ischemia caused the reversible neurologic deficit.

Aged↗
PubMed1984

Identification of a high-affinity binder for estradiol and a low-affinity binder for testosterone in Coccidioides immitis.

Coccidioides immitis cytosol contains a specific estrogen binder with kinetic characteristics (Kd = 2.1 X 10(-8) to 3.7 X 10(-8) M; n = 0.5 to 1.56 pmol/mg of protein) appropriate for interaction with levels of estrogen encountered during pregnancy. The Kd of a separate androgen binder (ca. 10(-7) M) is probably too low to allow interaction with physiological levels of testosterone.

Coccidioides↗