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Biomedical subjects

L Walton

Publications and source records attributed to L Walton.

At least 55 records · Page 3Linked to original sources
PubMed1992

Untoward clinical effects after stereotactic radiosurgery for intracranial arteriovenous malformations.

Stereotactic radiosurgery has become one of the most acceptable means of treating deep-seated intracranial arteriovenous malformations, as well as being a useful adjunct in a number of other pathologies. One hundred and sixty patients are discussed, having follow-up of at least 2 years. Radionecrosis occurred in six patients and haemorrhage in the latent period prior to thrombo-obliteration in a further six. Successful thrombo-obliteration was ultimately achieved in 76% of patients. As a bonus, epilepsy was improved in 29 of 48 patients presenting with seizures and worsened transiently in only three of these.

Adolescent↗
PubMed1990

Failure of trimethoprim-sulfamethoxazole therapy in experimental enterococcal endocarditis.

To assess the potential efficacy of trimethoprim-sulfamethoxazole (TMP-SMX) against serious enterococcal infections, we used a rat enterococcal endocarditis model comparing TMP-SMX therapy (500 mg of TMP plus 2,500 mg of SMX per kg of body weight per day given every 8 h by intragastric gavage) with intravenous ampicillin therapy (1,000 mg/kg per day). Despite concentrations of active drug in serum well in excess of the MIC and MBC, the mean residual vegetation bacterial titer in TMP-SMX-treated rats was similar to that in untreated controls (8.4 +/- 1.1 versus 8.6 +/- 1.3 log10 CFU/g) and significantly higher than that in the ampicillin-treated group (3.6 +/- 1.5 log10 CFU/g; P less than or equal to 0.001). This demonstrates discordance between in vitro activity and in vivo efficacy of TMP-SMX in serious enterococcal infection.

Ampicillin↗
PubMed1989

A phase I study of intraarterial iododeoxyuridine in patients with colorectal liver metastases.

Regional delivery of iododeoxyuridine (IdUrd) to patients with colorectal liver metastases was examined in a phase I study. The maximum-tolerated intraarterial (IA) dose (MTD) was 1,333 mg/m2/d administered continuously for 14 days. The dose-limiting toxicity was thrombocytopenia. Thrombocytopenia and leukopenia were correlated with the amount of IdUrd incorporated into DNA of peripheral granulocytes. In contrast to our experience with 5-fluorodeoxyuridine, there was no evidence of hepatobiliary toxicity. In 11 patients who received IA IdUrd alone, seven had a greater than or equal to 50% decrease in carcinoembryonic antigen (CEA) levels, with five having tumor volume reductions of 65%, 48%, 46%, 44%, and 27%. Thus, IA IdUrd alone has antitumor efficacy. Patients subsequently received IdUrd in combination with external beam radiation to a total dose of 2,400 cGy without acute local toxicity. In addition to these favorable clinical findings, we have previously shown that IdUrd is selectively incorporated into tumor DNA compared with normal liver in these patients. Further phase II evaluations of this approach are warranted.

Antineoplastic Agents↗
PubMed1988

Intraperitoneal chromic phosphate therapy after second-look laparotomy for ovarian cancer.

Between 1973 and 1985, 118 patients in clinical remission after initial surgery and postoperative chemotherapy for epithelial ovarian carcinoma underwent second-look laparotomy at the University of North Carolina. No evidence of disease (NED) was found in 57 of these patients; 43 patients received 15 mCi of radioactive chromic phosphate (32P) suspension given intraperitoneally in the immediate postoperative period. In 29 other patients, only microscopic or minimal residual disease (nodules less than 2 cm in size) was found, seven received 32P alone, ten received 32P and further chemotherapy, and 12 received chemotherapy alone. The 4-year postsecond-look survival of the patients with NED at second-look was 89% for those receiving 32P and 67% for those who had not. The respective figures for patients with minimal residual disease at second-look are 59% versus 22%. Irrespective of treatment, a group at high risk for failure after negative second-look laparotomy has been identified; those with an initial International Federation of Gynecology and Obstetrics (FIGO) stage greater than I and histologic grade greater than 1. A comparison of our data with 18 previously published series, indicates that use of postsecond-look intraperitoneal 32P can improve the progression-free interval, and possibly overall survival, of patients with NED or minimal residual disease without adding significant complications.

Carcinoma↗
PubMed1988

Peritoneal fluid cytology in endometrial cancer: its significance and the role of chromic phosphate (32P) therapy.

Between 1978 and 1986, 243 patients (all stages) had peritoneal fluid cytology performed while undergoing total abdominal hysterectomy for endometrial carcinoma; 39 (16%) were found to be positive. At 3 years (median follow-up of 30 months) the disease-free survival (DFS) for the 165 negative cytology clinical Stage I patients was 91% compared to only 56% for the 25 positive cytology patients (p less than .001). Of the 25 Stage I positive cytology patients, 14 with greater than one-third myometrial invasion had a DFS of 30% at 3 years as compared to 87% for negative cytology patients with comparable depth of invasion (p less than .001). There was no difference in DFS between the negative and positive cytology Stage I patients who had one-third or less myometrial invasion. Stage I patients with histologic Grade 2 and 3 had a lower 3 year DFS when cytology positive, 49% and 22%, versus 92% and 79% when cytology negative (p less than .001 and p = .03 respectively). In clinical Stage II patients the 3-year DFS was 21% for those with a positive cytology and 59% with a negative cytology. Fourteen of the 25 clinical Stage I positive cytology patients received 15 mCi of intraperitoneal 32P. At 3 years they had a 68% DFS as compared to 27% for those not receiving 32P (p = 0.01). All 11 patients with superficial myometrial invasion (9 received 32P) remained disease-free. The 4 Stage I patients with deep invasion who received 32P therapy had an improvement in abdominal/pelvic control and DFS when compared to 9 similar patients who did not receive 32P (p = .02). For histologic Grade 2 and 3 patients, there was a 64% 3-year DFS in the 32P treated group and 16% for those not receiving 32P (p = 0.02). Although 32P therapy improved DFS in Stage I positive cytology patients its use along with pelvic radiation therapy can lead to complications. Of 9 Stage I patients receiving 32P as well as pelvic irradiation, 4 experienced serious bowel complications requiring surgery. None of the 5 patients receiving 32P only had a complication.

Ascitic Fluid↗
PubMed1988

In vitro cleavable-complex assay to monitor antimicrobial potency of quinolones.

Seven quinolones were evaluated to determine whether their ability to generate the DNA gyrase-mediated cleavable complex correlated with their ability to inhibit the catalytic activity of purified DNA gyrase and inhibit the growth of Escherichia coli. The rank order of potency of these drugs in the cleavable-complex assay was essentially the same as in the DNA supercoiling-inhibition assay. It required 2- to 10-fold-lower drug concentrations to generate the cleavable complex than to inhibit E. coli DNA gyrase. With the newer fluoroquinolones, a 25- to 100-fold-greater concentration was required for DNA gyrase inhibition than for cell growth inhibition, suggesting a more subtle interaction between these inhibitors and DNA gyrase than mere enzyme inhibition.

DNA Damage↗
PubMed1987

Comparison of intravenous milrinone and dobutamine for congestive heart failure secondary to either ischemic or dilated cardiomyopathy.

Milrinone and dobutamine are positive inotropic agents with beneficial hemodynamic effects in patients with congestive heart failure. This study was undertaken to compare the effects of intravenous milrinone and dobutamine in patients with stable New York Heart Association class III or IV congestive heart failure and to test the hypothesis that intravenous milrinone is at least as beneficial as dobutamine in this setting. Seventy-nine patients were randomized to either dobutamine therapy at incremental doses of 2.5, 5, 7.5, 10, 12.5 and 15 micrograms/kg/min, or milrinone as a bolus of 50 or 75 micrograms/kg followed by an infusion of 0.5 to 1.0 micrograms/kg/min. Both agents significantly increased heart rate, cardiac index and stroke volume index and decreased pulmonary artery wedge pressure and systemic vascular resistance compared with baseline levels (p less than 0.01). During sustained infusion for 48 hours, no difference in hemodynamic effects was observed between the 2 drugs. Ventricular tachycardia occurred in 5 patients (3 taking milrinone, 2 taking dobutamine); 1 patient taking milrinone had ventricular fibrillation. Milrinone and dobutamine elicited similar beneficial hemodynamic results with relatively few adverse effects.

Cardiomyopathy, Dilated↗
PubMed1987

Flow cytometric analysis of human uterine sarcomas and cell lines.

Flow cytometric techniques were used to characterize multiple human uterine sarcomas and cell lines derived from some of these tumors. Analysis of DNA content showed that 9 of the 11 uterine sarcomas investigated were composed of at least one aneuploid population as well as a distinct diploid population. These data indicate that aneuploidy, as measured by flow cytometry, is a characteristic more common to uterine sarcomas than that previously reported for uterine adenocarcinomas. Unlike the original tumors, the cell lines established from three of the sarcomas contained predominantly diploid populations with only minor aneuploid populations. Treatment of one of the sarcoma cultures with tumor promoters did not result in an increase in the aneuploid populations. Tumors which arose in nude mice upon transplantation of two of the sarcomas did not contain the same distribution of tumor subpopulations as found in the original sarcomas. Apparently, the in vitro culture and and in vivo nude mouse conditions were not appropriate for maintaining the original equilibrium between the aneuploid and diploid subpopulations but instead provided a selective environment that resulted in the preferential growth of only certain tumor populations. Dual-parameter analysis of DNA content and alkaline phosphatase levels of one of the sarcomas were useful for distinguishing the aneuploid from the diploid population coexisting in this tumor. Our data suggest that flow cytometry is a valuable tool to analyze the characteristics of the tumor populations residing in primary uterine sarcomas as well as to determine which of these tumor subpopulations survive in culture and transplantation to nude mice.

Alkaline Phosphatase↗
PubMed1987

Primary radiation therapy for medically inoperable patients with endometrial carcinoma--stages I-II.

Surgery with or without adjuvant radiation is the established method of treating patients with Stage I and II adenocarcinoma of the endometrium. However, patients who are poor operative risks must be treated with radiation therapy only. We report on 73 such patients treated at the University of North Carolina between 1969 and 1980. All patients had an adenocarcinoma of the endometrium; 41 were FIGO Stage I, 32 Stage II. The minimum follow-up period was 4 years. Life table analysis shows a disease-free survival of 72% at 3 years and 57% at 5 years for Stage I patients. There was a strong correlation between histologic tumor grade and survival in these patients; the 5-year survival for grade 1 was 72%, for grade 2 59%, and for grade 3 31%. The difference between G1 and G3 is significant at the p = .045 level. Coexisting medical conditions were responsible for 12 deaths; almost as many as the 16 cancer-related deaths. Stage II patients have an actuarial disease-free survival of 36% at 3 years and 26% at 5 years, significantly worse than Stage I patients (p = .029 at 3 years). Failures were seen in 16/41 (39%) Stage I and 19/32 (59%) Stage II patients; 29/35 (83%) of these recurrences had component of local/pelvic failure and 15/35 (43%) of the recurrences were local/pelvic only. Specific suggestions on how to improve local therapy for these patients are presented.

Actuarial Analysis↗
PubMed1987

The Sheffield stereotactic radiosurgery unit: physical characteristics and principles of operation.

A stereotactic radiosurgery unit was commissioned in Weston Park Hospital in the summer of 1985. This paper describes the design, principles of operation and the safety features of the multiple-beam cobalt-60 therapy unit. The measurement of the dose around the extremely sharp focus produced by the 201 beams is discussed and the results compared with computed distributions. The results of the radiation protection survey are presented and the design of the purpose-built treatment suite is discussed. The procedure for treatment of a patient is outlined.

Brain↗
PubMed1987

Results of second-look laparotomy in patients with early-stage ovarian carcinoma.

One hundred twelve patients with early (FIGO stage I and II) ovarian carcinoma had a second-look laparotomy performed after comprehensive surgical staging and randomization into clinical protocols. Of the 95 patients who were asymptomatic before second-look laparotomy, only 5% had positive findings. In contrast, 53% of the 17 patients with findings that suggested recurrence or bowel obstruction had disease at second-look laparotomy. Overall, only 13% of the entire group of 112 patients had recurrent disease at second-look laparotomy. Asymptomatic patients with early ovarian carcinoma who have undergone careful initial surgical staging followed by appropriate adjuvant therapy can be spared a routine second-look operation.

Female↗
PubMed1985

Isolation of a dihydrofolate reductase-deficient mutant of Escherichia coli.

A strain of Escherichia coli was isolated in which dihydrofolate reductase was not detected by an enzyme assay or by competition for antibody. This strain requires methionine, glycine, a purine, and thymidine for growth in addition to the auxotrophic requirements of the parent strain. It was found to be useful as a recipient of plasmids harboring dihydrofolate reductase genes.

Escherichia coli↗
PubMed1985

Randomized trial of three cisplatin dose schedules in squamous-cell carcinoma of the cervix: a Gynecologic Oncology Group study.

The Gynecologic Oncology Group has conducted a randomized prospective trial comparing cisplatin 50 mg/m2 every 21 days (regimen 1), 100 mg/m2 every 21 days (regimen 2), and cisplatin 20 mg/m2 for five consecutive days repeated every 21 days (regimen 3). Four hundred ninety-seven evaluable patients have been accrued on this study. The response rates were 20.7%, 31.4%, and 25.0%, for regimens 1, 2, and 3, respectively; the complete remission rates were 10.0%, 12.7%, and 8.6% for regimens 1, 2, and 3, respectively. The median duration of response ranged from 3.9 to 4.8 months, the median progression-free interval from 3.7 to 4.6 months, and the median survival time from 6.1 to 7.1 months. The difference in response rates for regimens 1 and 2 is statistically significant (P = .015) but less than the magnitude originally considered clinically significant. The differences in complete remission rates, response duration, progression-free interval, and survival times are not statistically significant. The following types of toxicity were observed: serum creatinine level greater than 2 mg/dL and/or BUN level greater than 40 mg/dL was 7%, 14%, and 17% on regimens 1, 2, and 3, respectively; leukocyte count less than 4,000/microL was 27%, 44%, and 41% on regimens 1, 2, and 3, respectively. Nausea and vomiting occurred in 74 patients (83%). The regimen consisting of a 100-mg/m2 single dose has produced a statistically significant higher response rate than the 50 mg/m2 regimen while producing no appreciable differences in complete remission rate, response duration, progression-free interval, or survival. In addition, the higher dose regimen was associated with greater myelosuppression and nephrotoxicity.

Adult↗