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G Steele

Publications and source records attributed to G Steele.

186 records · Page 11Linked to original sources
PubMedDate not supplied

Spiral CT in the evaluation of flank pain: overall accuracy and feature analysis.

PURPOSE: Our goal was to assess test reliability and identify those features that have the strongest positive and negative predictive values in the diagnosis of renal colic using spiral CT. METHOD: Fifty non-contrast-enhanced CT scans (5 mm slice thickness) obtained in patients presenting with flank pain were reviewed by three radiologists blinded to the final diagnoses. The sensitivity, specificity, and positive and negative predictive values for nine pertinent findings were determined as compared to clinical follow-up. RESULTS: Twenty-nine cases had findings of ureteral obstruction. Findings with the strongest positive predictive values (> 0.90) were ureteral stone, hydronephrosis, hydroureter, periureteral stranding, and ureterovesical junction edema. Findings with the strongest negative predictive values (> 0.89) were absence of hydronephrosis and hydroureter. The areas under the receiver operating curves for Readers 1, 2, and 3 were 0.970 +/- 0.030, 0.942 +/- 0.036, and 0.982 +/- 0.020. CONCLUSION: Absence of hydroureter and hydronephrosis on spiral CT images should prompt a search for a diagnosis other than an obstructing ureteral stone.

Adult↗
PubMedDate not supplied

Liver cancer.

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Antineoplastic Agents↗
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Thymidine 5'-O-pivaloate: evidence for prodrug action in the rat and rhesus monkey.

Thymidine (TdR) 5'-O-pivaloate was administered to rats and a rhesus monkey to assess its prodrug characteristics. Within 15 minutes after a 2000-mg/kg oral or sc bolus in rats, free TdR was detected in the serum of liquid chromatography. At 1 hour the TdR level reached a plateau of approximately 0.6 mM with oral administration and 0.1 mM with sc treatment. In the monkey experiment, radioactivity was detected in the serum 15 minutes after oral administration of 200 mg/kg of [3H]TdR 5'-O-pivaloate. Thin-layer chromatographic analysis showed that this consisted of unchanged ester as well as free TdR and thymine. The concentration of intact ester reached a peak value of 5.4 microM after 40 minutes, before declining to a steady level of 0.9--1.0 microM over the next 6 hours. Serum [3H]TdR and [3H]thymine followed a similar course, except that both remained in the range of 1.0--1.2 microM for as long as 24 hours. Total recovery of radioactivity in the urine over the first 6 hours was 2.5% of the administered dose, will all compounds present in equal proportions. The results of these studies are consistent with absorption of intact pivaloate ester from the stomach, followed by gradual cleavage to TdR and catabolism of TdR to thymine and subsequent products. With a single oral dose of ester, it was possible to achieve, and maintain for up to 24 hours, a level (1 microM) of free TdR in the serum which has previously been found to protect normal tissues during high-dose methotrexate therapy.

Administration, Oral↗
PubMedDate not supplied

Adjuvant treatment of colorectal adenocarcinoma.

Colorectal adenocarcinoma is diagnosed in 150,000 Americans yearly, and more than 50,000 die of this disease each year. Recently, as a result of well-controlled, randomized, cooperative group trials, it has been demonstrated that adjuvant therapy of node-positive colon cancer (stage III) and node-positive or negative rectal cancer (stage II or stage III) can reduce recurrence and mortality and significantly improve overall survival. It is now the standard of care to provide adjuvant chemotherapy with 5-fluorouracil and levamisole for patients with node-positive colon cancer and provide adjuvant chemoradiotherapy with both 5-fluorouracil and high-dose radiotherapy for patients with stage II or stage III rectal cancer. It is estimated that these interventions, which are readily tolerated, will reduce the incidence of recurrence by more than 30% in both patient groups at a reasonable economic and health cost. Although the ideal method of therapy for this type of disease is not yet firmly established, it appears that adjuvant therapy for node-negative stage III colon cancer may be effective as well. Recently completed and ongoing cooperative group trials are investigating different combinations of chemotherapy and radiotherapy, including 5-fluorouracil with the biomodulator leucovorin or continuous-infusion 5-fluorouracil with radiotherapy, and comparing different durations of therapy. Other trials are investigating combined modality therapy for the neoadjuvant treatment of locally advanced rectal cancer. New findings in the genetics of colon cancer are being studied as prognostic information or markers to determine whether there are subsets of patients who might benefit from more or less therapy. Randomized placebo-controlled trials have been initiated to study the use of aspirin as a means of colon cancer prevention in high-risk populations. Taken together, the recent advances in our treatment and understanding of colorectal adenocarcinoma have resulted in a major--albeit silent--revolution in therapy and give firm promise for further progress.

Adenocarcinoma↗