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Biomedical subjects

D D Lawrence

Publications and source records attributed to D D Lawrence.

26 records · Page 2Linked to original sources
PubMed1986

Pretreatment effects on the uptake/retention kinetics of L-dopa in Harding-Passey melanoma.

Malignant melanoma cells possess a unique biochemical pathway that converts L-3,4-dihydroxyphenylalanine (L-dopa) to the biopigment melanin. Selective cytotoxic incorporation of exogenous L-dopa into melanoma cells in vivo may provide a means of designing specific chemotherapeutic agents useful in the treatment of this disease. Using the Harding-Passey murine melanotic tumor model, a preferential uptake of [3H]L-dopa by the tumor was characterized. Following pretreatment of the tumor-bearing mice with nonradioactive L-dopa, a significant enhancement (p less than 0.01) of [3H]L-dopa incorporation and retention into melanoma for a period of 24 h was observed, when compared with the concomitant tissue distribution and clearance of radioactivity in the control animals. This finding suggests that by initial pretreatment of melanoma with nonradioactive L-dopa, the subsequent selective accumulation of [3H]L-dopa in tumor may provide a useful tool in testing new modalities of therapy in malignant melanoma.

Adrenal Glands↗
PubMed1985

Postoperative respiratory complications in patients with Hodgkin's disease: relationship to the size of the mediastinal tumor.

Postoperative respiratory complications were investigated in patients with Hodgkin's disease, stages I-III, presenting with a mediastinal mass. By measuring the ratio between the widest diameter of the mediastinal mass and the width of the thorax at T5-6 (mediastinal thoracic ratio, MTR) in a PA chest X-ray, patients were divided into three groups: I: MTR less than 0.35 (41 patients); II: MTR 0.35-0.49 (33 patients); and III: MTR greater than 0.50 (23 patients). Five patients of group II and eight of group III received preoperative radiation therapy (RT) to the mediastinum due to severe clinical or radiological findings associated with the mediastinal mass. No patient of group I received preoperative RT. Without preoperative RT, group III had a significantly higher incidence of respiratory complications (7/15) compared to groups I (7/41) and II (2/28). Respiratory complications were not significantly different after preoperative RT in group III (1/8) compared to that observed in groups I plus II without preoperative RT (9/69).

Adolescent↗
PubMed1984

Hepatic artery ligation for liver metastasis in colorectal carcinoma.

From April 1975 to January 1982, 97 patients with greater than or equal to 50% of the liver involved with metastasis from colorectal carcinoma underwent hepatic artery ligation. The purpose was to evaluate median survival times in relation to performance status, synchronous intraabdominal metastasis, pulmonary metastasis, liver function tests (alkaline phosphatase, serum glutamic oxaloacetic transaminase (SGOT), lactate dehydrogenase (LDH), total bilirubin, and Dukes' staging. Results reveal that for performance status 0 to 1 (normal or symptoms, but ambulatory), median survival time was 12.3 months; status 2 to 3 (in bed less than or greater than 50% of time), 8.3 months; status 4 (100% bedridden), 2.6 months, (P less than 0.01). Median survival time in patients with only intrahepatic metastasis was 10 months versus 7 months for synchronous intraabdominal metastasis (P less than 0.01). For 20 patients with pulmonary metastasis undergoing hepatic artery ligation, the median survival time was 8.8 months (P less than 0.05). The median survival time in patients whose alkaline phosphatase was 2 times normal was 12.4 months, whereas, if alkaline phosphatase was 2 times to 4 times or greater than 4 times normal, median survival times were 7.1 and 6.9 months, respectively (P less than 0.01). Factors that adversely affect survival for hepatic artery ligation are extrahepatic metastasis, poor performance status, and elevated liver function tests (alkaline phosphatase 2 times normal). The overall median survival time in this study is 9.5 months with certain subgroups achieving 12.4 months' survival.

Adenocarcinoma↗
PubMedDate not supplied

A large lumen microcatheter for oncologic intervention.

A newly available Tracker-325 catheter (Target Therapeutics, Fremont, CA, USA), modified from the Tracker-18 catheter, has the same outer diameter but a larger lumen. This catheter was used in 15 patients during a 7-month period for superselective arterial catheterization when conventional catheters could not be placed successfully. Arterial embolization (n = 7), chemoembolization (n = 5), and chemoinfusion (n = 3), were performed. The increased luminal diameter of the Tracker-325 allowed an increased flow rate for diagnostic arteriography, accommodated larger embolic particles, and improved the ability to achieve a super-selective position.

Angiography↗
PubMedDate not supplied

Secretion of plasminogen activators by human colorectal and gastric tumor explants.

Conditioned media from explants of human colorectal and gastric tumors in short-term organ culture were analysed for plasminogen activator activity, activity toward the synthetic urokinase substrate, Spectrozyme-UK, and for the presence of urokinase antigen using monospecific goat antibody, by enzyme-linked immunosorbent assay. Comparisons were made between primary tumors, adjacent normal mucosa and metastatic lesions. These analyses were carried out on unfractionated culture fluids and on fractions obtained by fast protein liquid chromatography separation using Superose 6 gels. Plasminogen activator activity, tested by azocaseinolysis in the presence of added plasminogen, was restricted to peaks of 55 kD and 155 kD. These were of the urokinase type as shown by specific immunoinhibition and by absorption by an antiurokinase antibody-Affigel 10 column. Spectrozyme-UK, in addition to these peaks, detected a series of higher molecular weight activities, the largest of which appeared in the void volume, and were therefore of greater than 10(6) molecular weight. These activities were greatly increased by inclusion of trace plasmin indicating that these components were mostly in their proenzyme forms. The characteristics of these very large enzymes were similar to those isolated earlier from a human lung cancer cell line. Comparison of the primary and metastatic tumors confirmed earlier observations showing that urokinase secretion by the metastatic tumors was greatly reduced in comparison with the primary tumors: in the colon carcinomas it was 10 per cent of the value for the primary, in the gastric tumors 3 per cent, whether means or medians were compared (P less than 0.0001). This large difference was characteristic only of plasminogen activator secretion assayable by azocaseinolysis; activities toward Spectrozyme-UK, and antigen reacting with anti-urokinase antibody, were considerably less different in the two groups. In individual tissues, no correlation was found between the amount of extractable plasminogen activator and amounts secreted, or between the latter and the amount of lactic acid released. It is postulated that the greatly reduced plasminogen activator secretion by explants of metastatic tumors may be a phenotypic characteristic of distinct advantage for cancer cells destined to initiate metastatic foci, and may contribute to the ability of circulating cancer cells to lodge in the blood vessels of the target organ.

Chromatography, Liquid↗
PubMedDate not supplied

Percutaneous lymph node biopsy.

Advances in imaging modalities for detecting lymphadenopathy, the ease, safety, and accuracy of the tools and techniques, and the addition of refined ancillary studies for cytologic analysis will continue to increase the acceptance and use of percutaneous lymph node biopsy (PLNB) by fine-needle aspiration (FNA), especially in lymphomas.

Biopsy, Needle↗
PubMedDate not supplied

Intraperitoneal catheters: percutaneous placement with fluoroscopic guidance.

PURPOSE: The authors reviewed their experience with percutaneous placement of catheters into the peritoneal cavity for the administration of intraperitoneal chemotherapy to determine if their approach resulted in a lower complication rate than the reported 12%-16% rate and to demonstrate the technical advantages over surgically placed catheters. PATIENTS AND METHODS: Seventy-six patients with gastrointestinal or gynecologic malignancies underwent 152 procedures during a 20-month period. The catheters were used to deliver antineoplastic agents and, in some patients, to drain ascites. Catheter insertion was performed with local anesthesia and a modified Seldinger technique. A 5-F catheter was used in 89% of procedures; in the remainder, the catheter was of a larger caliber. RESULTS: The procedure was successful in 145 (95%) instances and failed in seven (5%) attempts because of peritoneal adhesions. The catheters remained in place for less than 2 days in 56%, 2-10 days in 25%, and more than 10 days in 19% of patients. One catheter remained in place for 15 weeks. Complications occurred in seven procedures (5%). Four cases of mild peritonitis responded to a brief course of intravenously administered antibiotics, and severe pain in two patients required premature catheter removal. A single case of inadvertent transcolonic catheter placement occurred without adverse sequelae to the patient. CONCLUSIONS: Intraperitoneal catheterization can be performed with local anesthesia by using a simple technique with a very low complication rate. The catheters can remain in place for prolonged periods without significant risks.

Adult↗