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D C Bowers

Publications and source records attributed to D C Bowers.

11 recordsLinked to original sources
PubMed2001

Intensive timed sequential remission induction chemotherapy with high-dose cytarabine for childhood acute myeloid leukemia.

BACKGROUND: Timed sequential chemotherapy and high-dose cytarabine (cytosine arabinoside, Ara-C; HDAC) are both effective treatments for acute myeloid leukemia (AML). We review our institutional experience with timed sequential induction chemotherapy consisting of daunorubicin/Ara-C/-thioguanine (DAT) or idarubicin/Ara-C/-thioguanine (IAT) followed on day 14 by HDAC regardless of the degree of marrow aplasia for children with newly diagnosed AML. PROCEDURE: Children presenting with newly diagnosed AML were treated with induction chemotherapy consisting of idarubicin (12 mg/m/day on days 1-3 or daunorubicin at 45 mg/m(2)/day for the first five patients), Ara-C (100 mg/m(2)/day by continuous infusion on days 1-7), and thioguanine (100 mg/m(2)/day on days 1-7). HDAC (1 g/m(2)/dose every 12 hr for 10 doses) was administered beginning on day 14, regardless of the results of bone marrow examination. RESULTS: Thirteen children received timed sequential HDAC. Only one child received HDAC later than Day 18. Eleven of the children achieved a complete remission. All patients experienced grade 4 hematologic toxicity, and all had fever as well. There were 11 children with documented infections. Ten had grade 3 or 4 GI toxicity. One patient died of sepsis. CONCLUSIONS: HDAC administered as a part of timed sequential therapy yields an excellent remission induction rate with manageable toxicity.

Adolescent↗
PubMed2001

Aggressive phenotypic and genotypic features in pediatric and NF2-associated meningiomas: a clinicopathologic study of 53 cases.

Pediatric and NF2-associated meningiomas are uncommon and poorly characterized in comparison to sporadic adult cases. In order to elucidate their molecular features, we analyzed MIB-1, progesterone receptor (PR), NF2, merlin, DAL-1, DAL-1 protein, and chromosomal arms 1p and 14q in 53 meningiomas from 40 pediatric/NF2 patients using immunohistochemistry and dual-color fluorescence in situ hybridization (FISH). Fourteen pediatric (42%) patients, including 5 previously undiagnosed patients, had NF2. The remaining 19 (58%) did not qualify. All 7 of the adult patients had NF2. Meningioma grading revealed 21 benign (40%), 26 atypical (49%), and 6 anaplastic (11%) examples. Other aggressive findings included high mitotic index (32%), high MIB-1 LI (37%), aggressive variant histology (e.g. papillary, clear cell) (25%), brain invasion (17%), recurrence (39%), and patient death (17%). FISH analysis demonstrated deletions of NF2 in 82%, DAL-1 in 82%, 1p in 60%, and 14q in 66%. NF2-associated meningiomas did not differ from sporadic pediatric tumors except for a higher frequency of merlin loss in the former (p = 0.020) and a higher frequency of brain invasion in the latter (p = 0.007). Thus, although pediatric and NF2-associated meningiomas share the common molecular alterations of their adult, sporadic counterparts, a higher fraction are genotypically and phenotypically aggressive. Given the high frequency of undiagnosed NF2 in the pediatric cases, a careful search for other features of this disease is warranted in any child presenting with a meningioma.

Adolescent↗
PubMed2001

Second surgery for recurrent pilocytic astrocytoma in children.

Pilocytic astrocytoma (PA) is the most common childhood brain tumor. In cases where the tumor progresses or recurs following primary surgical resection, the appropriate treatment is unclear. Options include chemotherapy, radiation therapy, surgical resection or a combination thereof. To analyze the utility of further surgery, we performed a retrospective, single-institution review of pediatric patients with recurrent PAs from 1990 to 1999 who were treated with a second surgical resection. Patients were excluded if they received adjuvant chemotherapy or radiation therapy. Twenty cases were identified. Tumor locations included: cerebral hemisphere (3), cerebellum (7), optic pathway/hypothalamus (5), thalamus (1) and brainstem (4). The indication for 4 surgeries included an enlarging tumor-associated cyst. At second surgery, 10 of 20 patients had a gross total resection (GTR), 2 a near total resection (NTR), and the remaining 8 patients had a subtotal resection (STR). No patients have died. Two of 10 tumors after GTR, 0 of 2 tumors after NTR, and 7 of 8 tumors after STR had second recurrence/progression at a mean of 15 months (range 4-33 months) following second surgery. The remaining 11 patients are recurrence/progression-free at a mean of 40.7 months (range 19-119 months). Surgery for tumors or midline structures rarely resulted in a GTR (1 of 10 cases). Surgery for tumors located in the cerebral hemispheres or cerebellum resulted in GTR or NTR in all cases and can result in long periods of progression-free survival without further adjuvant treatment.

Adolescent↗
PubMed2000

Scatter factor/hepatocyte growth factor protects against cytotoxic death in human glioblastoma via phosphatidylinositol 3-kinase- and AKT-dependent pathways.

We have shown recently that the multifunctional growth factor, scatter factor/hepatocyte growth factor (SF/HGF), and its receptor c-met enhance the malignancy of human glioblastoma through an autocrine stimulatory loop (R. Abounader et al., J. Natl. Cancer Inst., 91: 1548-1556, 1999). This report examines the effects of SF/HGF:c-met signaling on human glioma cell responses to DNA-damaging agents. Pretreating U373 human glioblastoma cells with recombinant SF/HGF partially abrogated their cytotoxic responses to gamma irradiation, cisplatin, camptothecin, Adriamycin, and Taxol in vitro. This cytoprotective effect of SF/HGF occurred at least in part through an inhibition of apoptosis, as evidenced by diminished terminal deoxynucleotidyl transferase-mediated dUTP nick-end labeling index and reduced DNA laddering. Anti-c-met U1/ribozyme gene transfer inhibited the ability of SF/HGF to protect against single-strand DNA breakage, DNA fragmentation, and glioblastoma cell death caused by DNA-damaging agents, demonstrating a requirement for c-met receptor function. Phosphorylation of the cell survival-promoting kinase Akt (protein kinase B) resulted from SF/HGF treatment of U373 cells, and both Akt phosphorylation and cell survival induced by SF/HGF were inhibited by phosphatidylinositol 3-kinase inhibitors but not by inhibitors of mitogen-activated protein kinase kinase or protein kinase C. Cytoprotection by SF/HGF in vitro was also inhibited by transient expression of dominant-negative Akt. Transgenic SF/HGF expression by intracranial 9L gliosarcomas reduced tumor cell sensitivity to gamma irradiation, confirming the cytoprotective effect of SF/HGF in vivo. These findings demonstrate that c-met receptor activation by SF/HGF protects certain glioblastoma cells from DNA-damaging agents by activating phosphoinositol 3-kinase-dependent and Akt-dependent antiapoptotic pathways.

Animals↗
PubMed2000

Tectal gliomas: natural history of an indolent lesion in pediatric patients.

The mesencephalic tectal glioma is a distinctive form of brain stem glioma with an unusually benign clinical course. Periaqueductal location, lack of contrast enhancement, and long periods of stability are classic features. The clinical management of these lesions, especially at the time of radiographic enlargement varies widely in the published literature. It is unclear whether these progressive lesions need to be treated. Accordingly, clinical and radiologic features of 7 patients were reviewed, with attention to the clinical course of the disease after radiologic enlargement. The age at diagnosis ranged from 3.3 to 16.6 years. Six of 7 had MRI tumor enlargement beginning 0.3-5.7 years after initial diagnosis. One of these 6 patients had radiographic progression coupled with a new clinical symptom which was treated with stereotactic radiation therapy. The remaining 5 patients with MRI progression and normal neurological exams were not treated and remain free of new neurologic deficits 1.8-6.9 years after the first radiographic tumor enlargement. The results suggest that pediatric tectal gliomas are a very low-grade lesion. Conservative management in the absence of new clinical symptoms could be argued, reserving radiotherapy or chemotherapy for clinical progression.

Adolescent↗
PubMed1984

Susceptibility and immunity to hepatitis B and rubella in a dental school population.

The incidence of hepatitis B infections and the rubella susceptibility of females was assessed in a dental school population, utilizing a commercially available enzyme immunosorbent assay. Surface antibody to hepatitis B virus was found in 8 percent of those individuals who provide direct patient care. The number of subjects nonimmune to rubella virus was 9 percent. Ninety percent of the individuals tested for past hepatitis B infection gave no knowledge of previous illness. More than half of the nonimmune rubella subjects gave a positive history of previous vaccinations or actual measles infection. This study supports the concern that patient histories present some shortcomings when used as monitors of disease history with regard to the rubella and hepatitis B viruses, and demonstrates the value of low-cost, expedient screening in institutions involved in educating health professionals.

Adolescent↗
PubMed1983

Chronic autoimmune thrombocytopenic purpura. A 3-year study.

Idiopathic (autoimmune) thrombocytopenic purpura (ATP) is accepted to be a disorder resulting from accelerated platelet destruction attributed to an autoimmune process. The patient whose case is presented in this article was first seen by a dentist. The oral findings have been documented as the case was followed for 3 years through acute exacerbations, pregnancy, and delivery of an infant with thrombocytopenia. The patient was managed with intermittent steroid therapy and splenectomy.

Adult↗