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D G Bostwick

Publications and source records attributed to D G Bostwick.

319 records · Page 18Linked to original sources
PubMed1983

Gastrin-releasing peptide-related peptides in a human malignant lung carcinoid tumor.

Recent immunohistochemical findings have indicated the presence of gastrin-releasing peptide in normal and pathological human lungs. Gastrin-releasing peptide is a 27-amino acid peptide isolated from porcine gut which bears considerable carboxyterminal homology with bombesin. We have characterized the gastrin-releasing peptide-like peptides present in a human malignant lung carcinoid tumor by gel chromatography and reverse-phase high-performance liquid chromatography. Our results show that this tumor did not contain bombesin; however, this tumor expressed a gastrin-releasing peptide-like compound, several amino-terminal fragments, and a carboxy-terminal fragment of gastrin-releasing peptide.

Amino Acid Sequence↗
PubMed1982

Radiation injury of the normal and neoplastic prostate.

Tissue samples from 40 patients with prostatic adenocarcinoma treated by radiation therapy were evaluated simultaneously by three observers to establish criteria for distinguishing residual tumor from radiation-induced atypia. Sections from 10 patients irradiated for nonprostatic pelvic neoplasms served as controls in addition to pretreatment biopsies from the determinate group. Patients had been treated by external x-irradiation, the majority receiving 6200-7400 rad to the prostate and pelvis over 7 to 8 weeks. Positive (tumor) biopsy incidence in the determinate group was 80% at 18 months, 40% at 36 months, and 43% in later samples. The following features were characteristic of radiation injury in the prostate: decreased ratio of the number of tumor glands to stroma, atrophy and squamous-like metaplasia of non-neoplastic glands with or without atypia, stromal fibrosis, arterial lumenal narrowing due to myointimal proliferation, foam cells within vessel walls, and fibrosis and atrophy of seminal vesicles. Criteria not useful for diagnosing radiation injury included architectural pattern or differentiation of tumor, cytologic features of tumor cells, inflammatory infiltrate, and ratio of normal glands to stroma. Ionizing radiation produced characteristic lesions in neoplastic and non-neoplastic prostatic glands, stroma, and blood vessels, and the sum of these changes was a reliable indicator of prior radiotherapy. An understanding of the morphologic effects of radiation injury of the prostate allowed distinction between residual prostatic adenocarcinoma and radiation-induced atypia of non-neoplastic glands.

Adenocarcinoma↗
PubMed1980

Morphological, growth, and chromosomal changes in bovine pancreatic duct epithelial cells exposed to N-methyl-N'-nitro-N-nitrosoguanidine.

Epithelial cells cultured from bovine pancreatic ducts were given a single treatment of N-methyl-N'-nitro-N-nitrosoguanidine (MNNG). Multinucleated cells and giant cells were observed more frequently in carcinogen-treated cultures than in controls. The MNNG-treated cultures also contained a sizeable population of small, dense cells that were not observed in control cultures. At the concentration of 1.0 microgram/ml, MNNG caused an initial depression in the growth rate of the cells followed by growth stimulation for several weeks. The MNNG produced chromosomal damage in the cells as indicated by the observation that a substantial proportion of carcinogen-treated cells were heteroploid and contained a high frequency of metacentric and submetacentric chromosomes and a dicentric marker chromosome. The MNNG treated and control cultures did not acquire the ability to grow in soft agar or to produce tumors after transplantation into athymic, nude mice.

Agar↗
PubMed1978

Isolation and characterization of epithelial cells from bovine pancreatic duct.

Epithelial cells derived from bovine pancreatic duct have been grown continuously in culture for 30 weeks (approximately 90 doublings of the cell population). The cells were grown in Eagle's minimal essential medium supplemented with 10% heat-inactivated fetal bovine serum, 2 mM glutamine, 0.1 mM nonessential amino acids, and antibiotics. In confluent cultures, the cells are multilayered and form circular structures. When tested at various passages, the cells neither formed colonies in soft agar nor produced tumors after inoculation into athymic, nude mice. Hydrocortisone (1 and 5 microgram per ml) and insulin (1,5 and 10 microgram per ml) had no effect on the growth of the cells. beta-Retinyl acetate inhibited growth rate and cell yield at a concentration of 5 microgram per ml but was not growth-inhibitory at lower concentrations. By electron microscopy the cells have numerous mitochondria, Golgi and microvilli. Mucous droplets were observed in a small proportion of the cells. Desmosome-like structures and occluding junctions were observed more frequently between cells that had been transferred as aggregates than between cells transferred as single cells. Cytochemical studies indicated that some cells produce PAS positive granules that were not removed after treatment of the cultures with diastase. Eleven cell clones were isolated from the mass culture. The growth rates of the clones are different as well as the period of time in which the clones can be propagated in vitro.

Animals↗
PubMedDate not supplied

Staging of prostate cancer.

The clinical and pathologic staging of prostate cancer involves determination of the anatomic extent and burden of tumor based on the best available data. Two major classification schemes are currently used: the modified American system and the TNM system [primary tumor (T), regional lymph node (N), and metastases (M)]. Both systems stratify patients according to the method of tumor detection, separating nonpalpable "incidental" prostate cancers detected during transurethral resection for clinically benign prostatic hyperplasia (BPH) and palpable cancers detected by digital rectal examination. These staging systems also recognize nonpalpable tumors detected by an elevated serum prostate-specific antigen (PSA) level or an abnormal transrectal ultrasound image. Current staging is limited by a significant level of clinical understaging (up to 59%, in our experience) and overstaging (up to 5%) according to comparison with pathologic examination of resected specimens. Proposed improvements in staging include preoperative systematic sextant biopsies to assess tumor volume, volume-based prognostic index, and a multiple prognostic index. In this report, we evaluate the current aspects of clinical and pathologic staging of prostate cancer with emphasis on the early stages in which there is the greatest chance of cure.

Evaluation Studies as Topic↗
PubMedDate not supplied

Evaluating prostate needle biopsy: therapeutic and prognostic importance.

Needle biopsy of the prostate plays a central role in the diagnosis of prostate cancer and the prediction of outcome. Strategies for sampling the prostate are being refined, which will increase the diagnostic yield. In combination with other clinical factors, the pathologic findings obtained from the biopsy specimen provide enhanced predictive accuracy for stage and individual outcome.

Biopsy, Needle↗
PubMedDate not supplied

The definition and preoperative prediction of clinically insignificant prostate cancer.

OBJECTIVES: To define clinically insignificant prostate cancer according to cancer volume, grade, cancer doubling time, and life expectancy; and to determine how many insignificant cancers are removed by radical prostatectomy. DESIGN AND PATIENTS: Clinically insignificant cancer was defined as a tumor that would give rise to no more than 20 cm3 of cancer within the prostate by the time of expected patient death (1990 life tables) and whose Gleason score was less than 4 in 40- to 49-year-olds, 5 in 50- to 59-year-olds, 6 in 60- to 69-year-olds, and 7 in 70- to 79-year-olds. Four definitions were formulated based on assumed cancer volume doubling times of 2, 3, 4, and 6 years. Using these four definitions, we reviewed 337 totally embedded prostates removed at Mayo Clinic between 1991 and 1993 for clinical stage T1c through T3 cancer to determine how many contained clinically insignificant cancer. MAIN OUTCOME MEASURES: Clinically significant vs clinically insignificant prostate cancer. RESULTS: For cancer volume doubling time of 2, 3, 4, and 6 years, clinically insignificant cancer was identified in one (0.3%), 13 (3.9%), 25 (7.4%), and 49 (14.5%) of 337 prostatectomy specimens, respectively. CONCLUSIONS: Clinically insignificant prostate cancer can be defined by cancer volume, grade, cancer volume doubling time, and life expectancy of the patient. According to our definitions, most men treated with radical prostatectomy have clinically significant cancer.

Adult↗
PubMedDate not supplied

The canine prostate is a spontaneous model of intraepithelial neoplasia and prostate cancer progression.

Increasing evidence suggests that high grade prostatic intraepithelial neoplasia (PIN) represents a precancerous stage in the morphologic continuum of progression from benign epithelium to carcinoma. In this report, we summarize our work characterizing the high grade PIN that occurs spontaneously in the canine prostate. The similarity between canine and human PIN for basal cell layer disruption, proliferative index, microvessel density, and its association with carcinoma suggest that the canine prostate may be a useful model for studying carcinogenesis and cancer progression.

Aging↗