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Biomedical subjects

L Bowman

Publications and source records attributed to L Bowman.

At least 37 records · Page 2Linked to original sources
PubMed1998

Costs and effects in therapy for acute coronary syndromes: the case of abciximab in high-risk patients undergoing percutaneous transluminal coronary angioplasty in the EPIC study. Evaluation of 7E3 for the Prevention of Ischemic Complications.

Cost-effectiveness analyses are routinely performed to determine whether the additional cost of a novel therapy is balanced by additional effectiveness. The definitions of costs and effects involve a variety of assumptions, both in general economic terms and with regard to the specific medical setting under consideration. Similarly, differing criteria for acceptability of cost-effectiveness estimates can be used to generate different conclusions regarding cost-effectiveness. The issues and problems inherent in economic evaluation are discussed by an analysis of findings with the platelet glycoprotein IIb/IIIa inhibitor abciximab in the EPIC (Evaluation of 7E3 for the Prevention of Ischemic Complications) study in high-risk patients undergoing percutaneous transluminal coronary angioplasty.

Abciximab↗
PubMed1998

Phase I study of DMP 840 in pediatric patients with refractory solid tumors.

The bis-naphthalimide DMP 840 has demonstrated high level antitumor activity in a number of preclinical models and has been evaluated in several Phase I studies in adults. We enrolled 10 patients with refractory pediatric solid tumors to this Phase I study of DMP 840 given intravenously by short infusion daily for 5 days. The most frequent and dose-limiting toxicity was myelosuppression. The maximum tolerated dose on this schedule was 8.6 mg/m2 daily for 5 days. One patient had a complete response; there were no measurable tumor responses among the remaining 9 patients.

Adolescent↗
PubMed1998

Constitutive nitric oxide production by rat alveolar macrophages.

Results from previous studies suggest that alveolar macrophages must be exposed to inflammatory stimuli to produce nitric oxide (.NO). In this study, we report that naive unstimulated rat alveolar macrophages do produce .NO and attempt to characterize this process. Western blot analysis demonstrates that the enzyme responsible is an endothelial nitric oxide synthase (eNOS). No brain or inducible NOS can be detected. The rate of .NO production is approximately 0.07 nmol.10(6) cells-1.h-1, an amount that is less than that produced by the eNOS found in alveolar type II or endothelial cells. Alveolar macrophage .NO formation is increased in the presence of extracellular L-arginine, incubation medium containing magnesium and no calcium, a calcium ionophore (A-23187), or methacholine. .NO production is inhibited by NG-nitro-L-arginine methyl ester (L-NAME) but not by NG-nitro-L-arginine, L-N5-(1-iminomethyl)ornithine hydrochloride, or aminoguanidine. Incubation with ATP, ADP, or histamine also inhibits .NO formation. Some of these properties are similar to and some are different from properties of eNOS in other cell types. Cellular .NO levels do not appear to be related to ATP or lactate content. Alveolar macrophage production of .NO can be increased approximately threefold in the presence of lung surfactant or its major component, dipalmitoyl phosphatidylcholine (DPPC). The DPPC-induced increase in .NO formation is time and concentration dependent, can be completely inhibited by L-NAME, and does not appear to be related to the degradation of DPPC by alveolar macrophages. These results demonstrate that unstimulated alveolar macrophages produce .NO via an eNOS and that lung surfactant increases .NO formation. This latter effect may be important in maintaining an anti-inflammatory state in vivo.

Adenosine Triphosphate↗
PubMed1998

Costs and effects in therapy for acute coronary syndromes: the case of abciximab in high-risk patients undergoing percutaneous transluminal coronary angioplasty in the EPIC study. Evaluation of 7E3 for the Prevention of Ischemic Complications.

Cost-effectiveness analyses are routinely performed to determine whether the additional cost of a novel therapy is balanced by additional effectiveness. The definitions of costs and effects involve a variety of assumptions, both in general economic terms and with regard to the specific medical setting under consideration. Similarly, differing criteria for acceptability of cost-effectiveness estimates can be used to generate different conclusions regarding cost-effectiveness. The issues and problems inherent in economic evaluation are discussed by an analysis of findings with the platelet glycoprotein IIb/IIIa inhibitor abciximab in the EPIC (Evaluation of 7E3 for the Prevention of Ischemic Complications) study in high-risk patients undergoing percutaneous transluminal coronary angioplasty.

Abciximab↗
PubMed1997

Outcome of treatment for pediatric sarcoma of the foot: a retrospective review over a 20-year period.

Soft tissue sarcomas (STS) arising in the foot are rare in children. From 1975 to 1994, 18 children (median age, 13.5 years) were treated at St Jude Children's Research Hospital for STS of the foot. Five children had rhabdomyosarcoma (RMS), with alveolar histology in four cases. All of these patients presented with metastatic disease, which proved fatal within 9 to 24 months despite combined modality treatment with chemotherapy, radiation, and surgery. Thirteen patients had nonrhabdomyosarcoma soft tissue sarcoma (NRSTS). The most common histological variant was synovial sarcoma (7 patients). Of the 10 who presented with localized disease, seven survived 1 to 12 years (median, 7 years). Surgical treatment for these consisted of local excision (n = 2), wide local excision (n = 3), below knee amputation (n = 1 ), ray amputation (n = 1). Three received supplemental radiation, and one was also treated with chemotherapy. Local or distant recurrence proved fatal in the three other children who had localized disease. Three children who presented with metastatic NRSTS died 8 to 14 months after diagnosis. All surviving patients are without significant functional disability. In our experience, pediatric RMS of the foot has a poor outcome, attributable to both alveolar histology and presence of metastatic disease at diagnosis. In contrast, NRSTS of the foot is more often localized, and limited surgery with adjuvant radiation in the absence of clear margins should be the treatment of choice.

Adolescent↗
PubMed1997

Alveolar type II cell cNOS activity and ATP levels are increased by lung surfactant or DPPC vesicles.

In a previous study, we reported that nitric oxide (.NO) affects surfactant synthesis and ATP levels in alveolar type II cells and suggested that there is constitutive nitric oxide synthase (cNOS) activity in the cells. In the present study, we performed experiments to confirm further the presence of cNOS and to determine the effects of lung surfactant on type II cell .NO and ATP levels. The supernatant from freshly isolated cells contains .NO (0.26 +/- 0.08 nmol/10(6) cells). During incubation, the cells produce additional .NO at a rate of approximately 0.3 nmol.10(5) cells-1.h-1. .NO formation is inhibited by 28-46% by three inhibitors of cNOS and inducible NOS (iNOS), NG-monomethyl-L-arginine (L-NMMA), L-N5-(1-iminoethyl)ornithine hydrochloride, and NG-nitro-L-arginine methyl ester, but a specific inhibitor of iNOS, aminoguanidine, has no effect. The production of .NO is reduced in Ca(2+)-free medium, is stimulated by the Ca2+ ionophore A-23187, and is independent of extracellular L-arginine. One known type of cNOS, endothelial NOS (eNOS), can be detected in the cells by using Western blot analysis. Incubation of the cells with lung surfactant leads to a relatively rapid (approximately 15 min), concentration-dependent increase in .NO formation that reaches levels as high as 238 +/- 14% of control. The surfactant effects appear to be caused by its major component, dipalmitoyl phosphatidylcholine (DPPC). Exposure of type II cells to DPPC results in maximal increases in .NO formation, ATP content, and O2 consumption, which are 268 +/- 32, 234 +/- 24, and 131 +/- 6% of control, respectively. The DPPC-induced increases in .NO, ATP, and O2 consumption are inhibited by L-NMMA. These results confirm the presence of type II cell cNOS and suggest that it may have a role in the cellular processing of lung surfactant.

1,2-Dipalmitoylphosphatidylcholine↗
PubMed1996

Exposure to crystalline silica or treatment with chlorphentermine increases vitamin E levels in rat alveolar lavage materials.

Previous studies have shown that vitamin E may be an integral part of lung surfactant and may function to protect this material from oxidant damage. Therefore, we measured the vitamin E levels in alveolar lavage materials from rats exposed to crystalline silica or treated with chlorphentermine (CP), two treatments that are known to increase surfactant phospholipids (PL) by different mechanisms. Silica exposure leads to increased PL synthesis, and CP treatment causes a reduction in PL degradation. Two different silica preparations, HCL-washed and unwashed silica, were used because exposure to each of them leads to different degrees of phospholipidosis. Exposure to HCL-washed silica results in a more than 17-fold increase in lavage PL and protein levels and a 12.2-fold increase in the amount of vitamin E. Exposure to unwashed silica leads to an approximately 7-fold increase in PL and proteins and a 5.8-fold increase in lavage vitamin E. Following treatment of rats with CP, there is a 15- to 19-fold increase in lavage PL and proteins and a 13.6-fold increase in vitamin E. When the results are expressed as micrograms vitamin E per milligram of lavage PL or protein, there is not much difference between controls and each treatment group. Because surfactant synthesis occurs in the endoplasmic reticulum, we also measured vitamin E in lung microsomes. Both silica exposure and CP treatment also lead to 1.8- to 2.5-fold increases, respectively, in the lung microsomal levels of vitamin E. These results demonstrate that alveolar lavage vitamin E levels are elevated along with lavage PL and proteins, and lung microsomal vitamin E levels are increased following exposure of rats to silica or treatment of the animals with CP.

Animals↗
PubMed1996

Economic assessment of platelet glycoprotein IIb/IIIa inhibition for prevention of ischemic complications of high-risk coronary angioplasty. EPIC Investigators.

BACKGROUND: In the EPIC trial, c7E3 Fab, an antiplatelet IIb/ IIIa receptor antibody, reduced 30-day ischemic end points after high-risk coronary angioplasty by 35% and 6-month ischemic events by 23% but increased in-hospital bleeding episodes. METHODS AND RESULTS: Of the 2099 patients randomized in EPIC, data were collected on 2038 (97%) for prospective hospital cost and major resources. Physician fees were estimated from the Medicare Fee Schedule. Regression analysis was used to examine the economic tradeoff between reduced ischemic events and increased major bleeding during the initial hospitalization. A potential cost savings of $622 per patient during the initial hospitalization from reduced acute ischemic events with c7E3 Fab was offset by an equivalent rise ($521) in costs as the result of an increase in bleeding episodes. Baseline medical costs for the bolus and infusion c7E3 Fab arm averaged $13,577 (exclusive of drug cost) compared with $13,434 for placebo (P = .42). During the 6-month follow-up, c7E3 Fab decreased repeat hospitalization rates by 23% (P = .004) and repeat revascularization by 22% (P = .04), producing a mean $1270 savings per patient (exclusive of drug cost) (P = .018). With a cost of $1407 for the bolus and infusion c7E3 Fab regimen, the cumulative net 6-month cost to switch from standard care to routine c7E3 Fab averaged $293 per patient. CONCLUSIONS: In high-risk coronary angioplasty, aggressive platelet inhibition with c7E3 Fab, by significantly reducing ischemic events and repeat revascularization, recoups most of the cost of therapy and has the potential to pay for itself.

Abciximab↗
PubMed1996

Pulmonary microsomal metabolism of benzo[a]pyrene following exposure of rats to silica.

Because some evidence suggests that there may be an increased incidence of lung cancer in silicosis and because previous studies have shown that exposure of rats to silica alters the pulmonary cytochrome P-450 system, we studied the effects of exposing rats to silica on the lung microsomal metabolism of benzo[a]pyrene (BaP). Rats were exposed to silica by intratracheal administration, lung microsomes were obtained 2 wk later from untreated and silica-treated animals, and the amounts of microsomal tissue and metabolites formed during the in vitro microsomal metabolism of BaP were measured. When the formation of BaP metabolites in equal amounts of lung microsomal tissue from the 2 treatment groups is compared, 3-OH BaP, BaP 4,5-diol, and BaP 9,10-diol are reduced by 45-70%, but the formation of BaP 7,8-diol or the BaP-quinones is not significantly altered following exposure to silica. In fact, the ratio of the BaP diols and BaP quinones, potentially toxic metabolites, to the relatively nontoxic 3-OH BaP produced by equal amounts of lung microsomal tissue is increased more than threefold following exposure of rats to silica. Since exposure of rats to silica leads to increased levels of lung microsomal protein, the amounts of BaP metabolites that could be produced by all microsomal tissue in the lungs were calculated. In silica-treated animals, the calculated total lung production of 3-OH BaP, BaP 4,5-diol, and BaP 9,10-diol tends to be increased by 1.2- to 2.0-fold, but BaP 7,8-diol and the BaP quinones are increased by 3.5-fold. These results demonstrate that exposure of rats to silica may alter the capacity of the lungs to metabolize benzo[a]pyrene, and the greatest effect seems to be enhanced accumulation of BaP 7,8-diol and the BaP quinones.

Animals↗
PubMed1996

Adverse drug reaction (ADR) occurrence and evaluation in elderly inpatients.

OBJECTIVE: Determine elderly inpatient's risk ADRs and characterize the events. DESIGN: This is a post-hoc analysis of a comprehensive inpatient ADR survey. Charts were reviewed every four days on all internal medicine service inpatients (1024 patients over four months). Chart review were enhanced by potential indicators such as nurses' and pharmacists' reports; targeted drug orders; 'now', 'stat', and 'hold' orders; off-service physician consults; incident reports; transfers-to-ICU; and abnormal serum drug concentrations. Potential ADRs were classified according to organ system affected, pharmacological type, severity, and Naranjo causality scale. SETTING: Internal medicine wards of a 350-bed county general hospital. RESULTS: Of 1024 inpatients, 301 were elderly. Overall, 237 patients had an ADR (23%). Elderly patients accounted for 89 (37.5%) of the 237 patients experiencing an ADR. The ADRs experienced by the elderly tended to be more severe (p <0.05) and less idiosyncratic (p <0.05). However, no preferences for organ system (p >0.1) or differences in causality rating (p = 0.25) were detected. When statistically controlled for female gender, renal function and number of drugs, age was no longer a risk factor for ADR occurrence. CONCLUSIONS: The elderly experience more ADRs. However, female gender, decline in renal function and polymedicine are the independent factors that account for the elderly's risk. Furthermore, the elderly's ADRs tend to be more severe and an extension of the drug's pharmacology. Therefore, ADR prevention is both important and possible.

Journal Article↗
PubMed1996

Epithelioid sarcoma in children.

Literature regarding the natural history and prognosis of epithelioid sarcoma in the pediatric population is sparse. During the past 11 years, eight patients with epithelioid sarcoma were treated at St Jude Children's Research Hospital. Of the eight children, six of whom were male, seven presented with localized disease and one with metastatic disease. The primary tumor was located in the upper extremity in four patients; the other sites were the scalp, external ear, back, and mediastinum. The mean duration of symptoms before diagnosis was 8.3 months (range, 1 to 12 months). Surgical treatment comprising amputation or wide local excision was performed in six patients, three of whom had additional lymph node dissection. Three patients received multiagent chemotherapy, and four patients were treated with supplementary radiation. Two patients died of progressive local and distant disease within 9 months of diagnosis. The other six patients are alive and have no evidence of disease 12 months to 10 years 6 months after the completion of treatment.

Adolescent↗
PubMed1996

Complications and effectiveness of gastrostomy feedings in pediatric cancer patients.

PURPOSE: The objective of this study was to assess the complications and efficacy of gastrostomy (GT) feedings in pediatric cancer patients. PATIENTS AND METHODS: We reviewed the medical records of 33 pediatric cancer patients who received enteral nutrition via a GT. RESULTS: Median age was 9.4 years (range, 1-19.8 years), and 28 of the 33 patients had solid tumors. Seventeen patients had a significant weight loss (median, 8.5%) and therapy-related weight loss was anticipated in 16 patients. The GT device was placed an average of 5.5 months after diagnosis. Twenty-five patients were fed via a tube and eight via a button device. The tube was placed surgically in 21 cases (including all eight button types) and endoscopically in 12. Nutritional support lasted a median of 9.5 months. One or more complications occurred in 30 patients and were categorized as (a) insertion site reactions (inflammation, 23; infection/colonization, 14; exuberant granulation tissue, 6); (b) mechanical problems (leaking, 3; obstruction, 2; breakage, 1; accidental dislodgement, 2); (c) insertion site bleeding, 8; and (d) feeding intolerance, 12. Only one insertion site cellulitis progressed to a systemic infection. All eight patients with a button GT experienced insertion site complications, with local infection occurring significantly more often in patients with the button than in those with the tube GT. There were no significant associations between insertion technique and type of complication. Twenty-seven patients (82%) achieved or maintained ideal body weight with this intervention. CONCLUSIONS: GT feeding was associated with minor complications, but permitted effective nutritional support for pediatric cancer patients.

Adolescent↗
PubMed1996

Nitric oxide alters metabolism in isolated alveolar type II cells.

Alveolar type II cells may be exposed to nitric oxide (.NO) from external sources, and these cells can also generate .NO. Therefore we studied the effects of altering .NO levels on various type II cell metabolic processes. Incubation of cells with the .NO generator, S-nitroso-N-acetylpenicillamine (SNAP; 1 mM), leads to reductions of 60-70% in the synthesis of disaturated phosphatidylcholines (DSPC) and cell ATP levels. Cellular oxygen consumption, an indirect measure of cell ATP synthesis, is also reduced by SNAP. There is no direct effect of SNAP on lung mitochondrial ATP synthesis, suggesting that .NO does not directly inhibit this process. On the other hand, incubation of cells with NG-nitro-L-arginine methyl ester (L-NAME), an inhibitor of nitric oxide synthase (NOS), the enzyme responsible for .NO synthesis, results in increases in DSPC synthesis, cell ATP content, and cellular oxygen consumption. The L-NAME effects are reversed by addition of L-arginine, the substrate for NOS. Production of .NO by type II cells is inhibited by L-NAME, a better inhibitor of constitutive NOS (cNOS) than inducible NOS (iNOS), and is reduced in the absence of external calcium. Aminoguanidine, a specific inhibitor of iNOS, has no effect on cell ATP content or on .NO production. These results indicate that alveolar type II cell lipid and energy metabolism can be affected by .NO and suggest that there may be cNOS activity in these cells.

Adenosine Triphosphate↗
PubMed1996

P-glycoprotein expression at diagnosis may not be a primary mechanism of therapeutic failure in childhood rhabdomyosarcoma.

PURPOSE: To evaluate the prognostic significance of tumor cell P-glycoprotein (Pgp) expression at diagnosis in children with rhabdomyosarcoma. PATIENTS AND METHODS: A panel of three anti-Pgp monoclonal antibodies (mAb) (C219, C494, and JSB-1) that recognize different Pgp epitopes was used to measure Pgp expression in rhabdomyosarcoma specimens obtained at diagnosis from 76 patients treated at St Jude Children's Research Hospital from 1969 to 1991. Two separate experiments using different immunohistochemical methods (immune alkaline phosphatase and immunoperoxidase) were performed to evaluate Pgp expression. The immunostaining was graded using a semiquantitative scale corresponding to the percentage of tumor cells with detectable staining. The influence of Pgp expression on outcome was assessed by the Kaplan-Meier method and Cox regression analysis with stepwise selection. The relationship between Pgp expression and clinical features was assessed using the Mantel-Haenszel method. RESULTS: Pgp expression at diagnosis did not predict worse overall survival or progression-free survival when tested in either experiment with C219, C494, or JSB-1 separately. No association was shown between Pgp expression and clinical features (clinical group, primary site, or histology) or response. However, in the immune alkaline phosphatase experiment, patients whose tumors had more than 10% tumor cell staining with all three mAbs had a significantly higher rate of estimated 5-year survival (78% +/- 10%) than did all other patients (38% +/- 8%; P = .025). In this instance, Pgp expression had independent prognostic value after adjusting for clinical group. CONCLUSION: We found no strong association between Pgp expression at diagnosis and clinical features or extent of disease in pediatric rhabdomyosarcoma. Depending on the criteria used to define it, high Pgp expression at diagnosis does not predict poor outcome. Although a large prospective study is needed to provide definitive conclusions, our findings suggest that Pgp-mediated multidrug resistance may not be a primary mechanism of therapeutic failure in rhabdomyosarcoma.

ATP Binding Cassette Transporter, Subfamily B, Mem↗
PubMed1995

A phase II trial evaluating selective use of altered radiation dose and fractionation in patients with unresectable rhabdomyosarcoma.

PURPOSE: Between 1987 and 1991, 25 children with advanced rhabdomyosarcoma (20 with IRS Group 3 disease and 5 with Group 4 disease) were entered on a prospective study evaluating selective use of hyperfractionated irradiation (HFI) and reduced-dose conventionally fractionated irradiation (CFI), based on disease status following induction chemotherapy (ifosfamide or melphalan, followed by vincristine, adriamycin, and cyclophosphamide combination) with or without delayed surgery. METHODS AND MATERIALS: Patients with gross disease following induction chemotherapy with or without delayed surgery, and whose primary tumor sites did not involve the central nervous system, received HFI (n = 12) at 1.1 Gy twice-a-day to 59.4-63.8 Gy total. Patients with parameningeal primaries and intracranial disease extension received HFI with initiation of therapy (n = 2). Those with microscopic disease following induction chemotherapy with or without delayed surgery (n = 11) received reduced-dose CFI to 40 Gy. Active follow-up ranges from 28-75 months (median = 43 months) with no patient lost to follow-up. RESULTS: Eighteen patients (72%) are alive and without evidence of disease, including 8 of the children with gross residual disease postinduction therapy. The absolute 2-year continuous local tumor control rate is 86% for all patients. Among the 14 who received HFI, the absolute 2-year continuous local tumor control rate is 75% at 33 to 67 months (median = 38 months) postirradiation. Hyperfractionated irradiation was associated with expected enhancement of acute reactions, which all resolved with conservative medical management. Grade 4 or 5 acute toxicities were not seen. Significant late radiation morbidity has, thus far, been minimal and limited to Grade 1 and 2 events. Among the 11 who received reduced-dose CFI, the absolute 2-year continuous local tumor control rate is 100% at 25 to 70 months (median = 40 months) postirradiation. CONCLUSION: This limited experience suggests that HFI to a dose level of 60 Gy can be used selectively in children with advanced rhabdomyosarcoma left with gross disease following induction chemotherapy, with or without delayed surgery, with an apparent improvement in local control, and minimization of potential late radiation toxicity. Concurrently, those left with microscopic disease following induction therapy can be selectively treated with reduced-dose CFI with excellent local control.

Adolescent↗