Biomedical subjects

I D Kaplan

Publications and source records attributed to I D Kaplan.

24 records · Page 2Linked to original sources

PubMed1992

The importance of local control in the treatment of prostatic cancer.

In a retrospective analysis of 946 patients with prostatic carcinoma treated with external beam radiotherapy between 1958 and 1989 at Stanford University Hospital the 15-year actuarial clinical local control rate was 77.8 +/- 3.3% for Stanford stage T1, 61.3 +/- 4.4% for stage T2 and 64.9 +/- 4.8% for stage T3 disease. Overall, there was improvement in disease-specific survival without a significant alteration in survival in patients who achieved clinical local control. For the 50 Stanford stage T1 cases with local control on clinical examination and a positive post-treatment biopsy a decrease in disease-specific survival was observed. There was no difference in disease-specific survival for comparable stage T2 or T3 cases. In an analysis of patients who underwent ultrasound guided prostatic biopsy performed after irradiation the trend of prostate specific antigen was more important than biopsy results in predicting which patients would have relapse.

Follow-Up Studies↗

PubMed1991

A model of prostatic carcinoma tumor kinetics based on prostate specific antigen levels after radiation therapy.

Serial prostatic specific antigen values (PSA) were determined on 42 patients receiving definitive radiation therapy for localized adenocarcinoma of the prostate. The PSA declined exponentially in 25 patients. None of these patients experienced metastases. The PSA initially declined then increased exponentially in 17 patients. The rate of decline was similar to the rate of rise in all 17 patients. Five of these patients had distant metastases (P less than 0.02) within 2 years of treatment. The PSA values after radiation therapy were employed to formulate a model of tumor kinetics. This model predicts the mean duration of G0. This parameter is correlated with the development of distant metastases within 2 years of treatment. For those patients at low risk for relapse, the mean G0 is calculated to be 22.5, and 13.6 weeks for those who have relapsed or are at high risk for relapse.

Adenocarcinoma↗

PubMed1990

Reduction of spinal metastases after preemptive irradiation in prostatic cancer.

For this study, 136 patients treated at Stanford University Hospital for prostatic cancer between 1971 and 1980 were selected for review. The patients had received no prior therapy, and had no evidence of bone metastases at time of radiation treatment based on radiographic studies and bone scan. Of this group, 71 patients received extended-field irradiation (paraaortic and pelvic fields), and 65 patients received pelvic irradiation. The pelvic field was treated to 50 Gy and the paraaortic field received 45 Gy to 60 Gy. All patients subsequently underwent routine follow-up examinations and studies at Stanford University Hospital: 1,513 follow-up X rays, bone scans, and CT-scans were analyzed for site-specific recurrence. The follow-up ranged from 14 months to 16 yrs from the time of initial treatment, with a mean follow-up of 7 yrs. Lower extremities and ribs were found to be the most common sites of bone metastases. Irradiation of the lumbar spine to a dose of 35 to 60 Gy, coincidental to irradiation of the paraaortic lymph nodes prevented or delayed the development of lumbar spine metastases. The potential mechanism and clinical implications are discussed.

Bone Neoplasms↗

PubMed1990

Early and late bone-marrow changes after irradiation: MR evaluation.

Knowledge of the chronologic evolution of bone-marrow changes during and after radiation therapy is essential in differentiating normal postradiation changes from other marrow abnormalities. The appearance of the lumbar vertebral bone marrow was studied on 55 serial spin-echo and short-T1 inversion-recovery (STIR) MR images obtained in 14 patients receiving radiation therapy for Hodgkin disease, seminoma, or prostate carcinoma. Images were obtained before, at weekly intervals during, and at various monthly intervals up to 14 months after a 3- to 6-week course of fractionated paravertebral lymph-node irradiation of 1500-5000 rad (15-50 Gy). During the first 2 weeks of therapy, there was no definite change in the appearance of the marrow on spin-echo images; however, there was an increase in signal intensity on the STIR images, apparently reflecting early marrow edema and necrosis. Between weeks 3 and 6, the marrow showed an increasingly heterogenous signal and prominence of the signal from central marrow fat, shown best on T1-weighted images. Late marrow patterns (6 weeks to 14 months after therapy) varied and consisted of either homogenous fatty replacement or a band pattern of peripheral intermediate signal intensity, possibly representing hematopoietic marrow surrounding the central marrow fat. No focal marrow lesions or soft-tissue edema were identified during the course of radiation therapy; their presence should raise the possibility of the presence of a pathologic process other than radiation change. These data suggest that MR can detect radiation-induced marrow changes as early as 2 weeks after starting therapy, and that there are at least two distinct types of late marrow MR patterns.

Adolescent↗

PubMed1986

Metabolic properties of human acetylcholine receptors can be characterized on cultured human muscle.

Experiments examining acetylcholine receptor (AChR) metabolism in tissue culture have hitherto been limited to animal systems. For many studies, the human AChR on human skeletal muscle provides a more physiologic target. However, previous studies suggested that the levels of AChR produced on cultured human muscle were inadequate for metabolic studies. We demonstrate here that the metabolism of human acetylcholine receptors can be analysed on pure human muscle fibers that develop in tissue culture. Degradation of AChR follows first-order kinetics and is inhibited 85% by leupeptin, demonstrating that proteolysis of human AChR occurs in the lysosome. New AChR continue to appear on the cell surface for 3 h in the presence of cycloheximide, indicating the existence of a pool of intracellular AChR destined for the cell membrane. This pool is equivalent to approximately one-third of the AChR present on the surface of the cell. At any given time, the rate of AChR accumulation on the cell surface can be quantitatively accounted for by the rates of synthesis and degradation. Our results demonstrate that studies on the effects of hormones, neurotoxins or antibodies from patients with autoimmune neuromuscular diseases are now possible with human AChR which develop on intact human muscle myotubes formed in tissue culture.

Cell Differentiation↗

PubMedDate not supplied

Feasibility and patient tolerance of a novel transrectal ultrasound hyperthermia system for treatment of prostate cancer.

This report describes patient tolerance and toxicity of a transrectal ultrasound hyperthermia system used with external beam radiation therapy in treatment of locally advanced prostate cancer. Nine patients with clinical T2B-T3B (4th edition AJCC criteria) disease received external beam radiation therapy, with two hyperthermia treatments scheduled at least 1 week apart during the first 4 weeks of radiation. Five patients also received hormonal therapy. Interstitial and anterior rectal wall thermometry were performed. Median temperature for each treatment (T50) was 40.8 degrees C and mean CEM T90 = 43 degrees C was 3.4 min. Rectal wall temperature was maintained at < or = 40 degrees C. Treatment duration was limited in three of 17 sessions due to positional discomfort which was alleviated with light IV sedation and use of a 'New Life' mattress (Comfortex, Inc. Winoba, MN, USA). Acute toxicity was limited to NCI common toxicity criteria grade 1 and no excess toxicity was noted with full course radiation therapy +/- hormonal therapy. These findings are consistent with those reported in a previous phase I trial assessing this device. Given the favourable toxicity profile demonstrated to date, modification of treatment parameters for this ongoing phase II study have been instituted that should further the efficacy of transrectal ultrasound hyperthermia for treatment of prostate cancer.

Aged↗