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Biomedical subjects

D Lister

Publications and source records attributed to D Lister.

At least 19 recordsLinked to original sources

An estimate of the cost of conducting phase II trials in lung cancer.

OBJECTIVE: Although it is commonly assumed that clinical trials are more costly than standard therapy, there have been no previous studies of the cost of conducting phase II trials in lung cancer. We retrospectively analyzed two National Cancer Institute of Canada phase II trials in previously untreated small cell lung cancer (SCLC) to determine the costs of conducting the trials in a cancer treatment centre. Both studies were clinical trials undertaken as part of the NCIC's Investigational New Drug program: IND 69 and IND 50 evaluated docetaxel (taxotere) and gemcitabine, respectively. METHODS: data management costs in a Canadian cancer treatment centre were determined from the time estimates provided by data managers to complete various protocol related tasks. Nursing and pharmacy personnel measured the time and supplies necessary to prepare and administer the chemotherapy. Physician fees were determined from the type and number of care visits required by the clinical protocols. Laboratory tests and imaging studies were costed according to the Ontario Health Insurance Plan (OHIP) Schedule of Fees and Benefits. To estimate whether phase II trials are more costly than standard treatment, we determined the cost of four cycles of VP-16-cisplatin, a standard treatment for SCLC. RESULTS: The total cost of performing the docetaxel study was $18443 for an average cost per case of $1317 and an average cost per treatment cycle of $683. The gemcitabine study cost more, due to the fact that the drug proved to be active against SCLC and more cycles of therapy were administered to a larger number of patients. Laboratory and administration costs were also higher, because of the drug administration schedule. The total cost of this study was estimated to be $64670 and the average cost per patient entered was $2230 with an average cost per treatment cycle of $898. In comparison, the estimated cost of four cycles of VP-16-cisplatin chemotherapy was $3948 or $987 per treatment cycle. The major cost drivers in the clinical trials were laboratory and imaging tests which made up 17 and 39%, respectively, of the costs of the taxotere study, and 29 and 27%, respectively, for the gemcitabine study. Data management costs contributed 21 and 13% of the total costs, respectively. CONCLUSION: As the main cost drivers in these phase II clinical trials are laboratory and imaging tests, the cost of clinical trials could potentially be reduced by ensuring that only essential tests are required by protocol. Not surprisingly, the cost of conducting a trial of an active agent is greater than for an inactive agent, because more patients are treated and each patient receives more treatment. The implications for the per-case funding of phase II clinical trials are discussed.

Antineoplastic Combined Chemotherapy Protocols↗

The accuracy of breast ultrasound in the evaluation of clinically benign discrete, symptomatic breast lumps.

INTRODUCTION: Recent reports have suggested that breast ultrasound (US) is of value in distinguishing malignant from benign processes. The aim of this study was to establish the accuracy of US in detecting invasive malignancy in clinically benign, discrete, symptomatic breast lumps. METHODS: The US appearances of 205 clinically benign breast masses were documented prospectively and prior to mammography by one radiologist (AJE). The US appearances were then correlated with the fine needle aspiration (FNA), core biopsy and surgical findings and compared with the mammographic findings. RESULTS: The US findings were normal 72 (35%), simple cyst 63 (31%), solid benign 51 (25%), solid indeterminate 15 (7%) and solid malignant four (2%). Ultrasound characterized 13 (93%) of the 14 patients found to have invasive carcinoma as indeterminate or malignant. No patients with normal or simple cyst US findings had invasive malignancy. Ultrasound had significantly better accuracy (97% vs 87%, P < 0.02) sensitivity (93% vs 57%, P < 0.05) and negative predictive value (99% vs 92%, P < 0.002) than mammography in the detection of invasive carcinoma when indeterminate and malignant imaging findings were taken as positive. CONCLUSION: US is a useful adjunct to FNA/core biopsy in confirming the nature of symptomatic, clinically benign breast masses and is superior to mammography in this clinical setting.

Adult↗

Reduction of the infectivity of scrapie agent as a model for BSE in the manufacturing process of Trasylol.

The Trasylol manufacturing process was investigated with respect to its capacity for the inactivation/removal of infectivity causing bovine spongiform encephalopathy (BSE). Four process steps were selected for this investigation and scaled down to laboratory scale. Authentic samples of bovine lungs used in the Trasylol manufacturing plant were taken and spiked in laboratory scale experiments with high infectious titres of the rodent adapted scrapie strain ME 7 which served as model for BSE. After performing the respective process steps the output samples collected were tested in C57BL mice carrying the Sinc gene. An overall reduction of the infectious agent in the order of 18 log10 was observed, indicating a very high capacity of the Trasylol process for the inactivation/removal of the BSE/scrapie agent. The discussed safety strategy for the product leads to the conclusion that Trasylol is BSE safe.

Animals↗

Thyroid activity in relation to growth rate and body composition in four breeds of sheep.

Four breeds of sheep, Hampshire, Southdown, Cheviot and Scottish Blackface, which differ in mature body size and body composition were intensively reared under an ad libitum or a restricted feeding regime. Thyroid activity was assessed at 13 weeks of age by the 131I uptake method. Slaughter at 24 weeks (ad lib) or 32 weeks (restricted) was followed by carcass dissection. The anticipated differences in body type represented by the 4 breeds was confirmed in terms of size and fatness. The Hampshires had the highest growth rate (liveweight for age) and the lowest thyroid uptake, and the breed differences in thyroid activity were shown to be independent of liveweight. Thyroid activity was positively related to growth rate in the Hampshires and negatively related to growth rate in the 3 other breeds. No association could be found however between the thyroid activity and the proportionate growth of body fat or lean. None of these conclusions were affected by a mild restriction in fed intake.

Analysis of Variance↗

The comparative pharmacokinetics and tissue penetration of four quinolones including intravenously administered enoxacin.

The pharmacokinetics and tissue penetration of four quinolones were studied. The compounds were norfloxacin (400 mg p.o.), enoxacin (600 mg p.o. and 400 mg i.v.), ciprofloxacin (100 mg i.v. and 500 mg p.o.) and ofloxacin (600 mg p.o.) given to healthy volunteers. Of the oral agents studied ofloxacin and ciprofloxacin were the most rapidly absorbed (Tmax 1.2 h) and enoxacin the least (Tmax 1.9 h). The serum levels attained were highest in the case of ofloxacin (after allowing for the higher dose administered). The serum half-lives were norfloxacin 3.75 h, ciprofloxacin 3.9 h (p.o.), 4.0 h (i.v.), ofloxacin 7.0 h and enoxacin 6.2 h (p.o.) and 5.1 h (i.v.). All agents penetrated the blister fluid readily. The 24 h urine recovery (as measured by a microbiological assay) was 62% for enoxacin (p.o.), 46.4% following i.v. enoxacin (plus 11.6% oxo-enoxacin, measured by HPLC) 27% for norfloxacin, 30.6% for oral ciprofloxacin, 75.7% for i.v. ciprofloxacin and 73% for ofloxacin.

Adult↗

The comparative pharmacokinetics of five quinolones.

The pharmacokinetics and tissue penetration of five quinolones were studied in volunteers. The compounds were norfloxacin (400 mg po), enoxacin (400 mg iv and 600 mg po), ciprofloxacin (100 mg iv and 500 mg po), ofloxacin (600 mg po) and pefloxacin (400 mg iv). Of the oral agents studied ofloxacin and ciprofloxacin were the most rapidly absorbed (Tmax = 1.2 h) and enoxacin the least (Tmax = 1.9 h). The serum levels attained were highest in the case of ofloxacin (after allowing for the higher dose administered). The serum half-lives were norfloxacin 3.75 h, ciprofloxacin 3.9 h (po), 4.0 h (iv), ofloxacin 7.0 h, enoxacin 6.2 h (po), 5.1 h (iv) and pefloxacin 10.5 h. All agents penetrated blister fluid readily. The 24 h urine recovery was 62% for oral enoxacin, 46.4% for iv enoxacin (plus 12.2% for oxo-enoxacin), 27% for norfloxacin, 30.6% for oral ciprofloxacin, 75.7% for iv ciprofloxacin, 73% for ofloxacin and 4.9% for pefloxacin (plus 9.2% for the norfloxacin metabolite and 17.8% for pefloxacin N-oxide).

Administration, Oral↗

Adipose tissue capillary blood flow in relation to fatness in sheep.

Capillary blood flow rate was measured in eight fat depots in eight Blackface and eight Clun lambs using the radiolabelled microsphere technique. Adipose tissue flow ranged from 3 to 47 ml 100 g-1 min-1 depending upon depot and degree of fatness. Blood flow declined with increasing fatness suggesting that perfusion was not an important constraint on the growth of fat. Blood flow rates were also measured in the fed and 26 hour fasted states but no effect from fasting was observed.

Adipose Tissue↗

The effect of passive immunization against somatostatin on marker retention time in lambs.

The effects of passive immunization against somatostatin on retention time of marker have been investigated in sheep using Cr2O3 as a marker. The mean transit time for clearance of 50% of the marker was significantly retarded in all the anti-somatostatin-treated animals by approximately 19.0 h, as compared with control lambs given a nonspecific antiserum. The findings suggest an important role for circulating somatostatin in the regulation of the rate of flow of digesta through the gastrointestinal tract in lambs. Moreover, it enhances the claim of the immunological approach as a new technique to investigate factors controlling food utilization in farm livestock.

Animals↗

The effect of alpha-adrenergic blockade on the release of ACTH and cortisol in vivo.

The effect of alpha-adrenergic blockade, by phentolamine, upon plasma levels of adrenocorticotrophic hormone (ACTH) and cortisol during insulin-induced hypoglycaemia was studied in pigs. Insulin administration produced a rise in ACTH which reached a maximum at about 30 minutes (p less than 0.01) and had returned to basal levels by 90 minutes. Cortisol levels had also risen by 30 minutes and remained elevated for 90 minutes. Pre-treatment with phentolamine almost completely suppressed the growth hormone response to insulin-induced hypoglycaemia, but had no effect upon the amplitude or duration of the elevation of plasma ACTH or cortisol levels following insulin administration. The hypoglycaemia-induced rise in ACTH and cortisol seem, therefore, to be independent of the alpha-adrenergic system. In addition, the inhibitory action of the alpha-adrenergic system on ACTH release reported in rats and dogs does not appear to be present in pigs.

Adrenergic alpha-Antagonists↗

Effect of dantrolene on leg metabolism in porcine malignant hyperthermia.

The effect of the intravenous administration of dantrolene 3.5 mg/kg body weight on leg metabolism during porcine malignant hyperthermia (MH) was investigated in six Pietrain pigs. Arterial pH improved only slowly after dantrolene and was associated with the continuing efflux of lactate from the leg. Oxygen uptake by the leg had returned to control values 30 minutes after dantrolene. Glucose production by the leg was observed during malignant hyperthermia but this was rapidly abolished by dantrolene. It is concluded that the most useful indices for assessing the adequacy of the treatment of MH are those which reflect changes in oxidative muscle metabolism.

Animals↗

The effect of chronic neonatal guanethidine treatment on body composition in pigs.

The effect of neonatal guanethidine administration (30 mg/kg/day) during the first 32 days of life on body composition at 20 weeks of age, was assessed in two breeds of pig which were known to differ in their sympathetic responsiveness. Guanethidine administration increased the proportion of fat and decreased the proportion and absolute weight of lean in the Pietrain breed; and it had no effect in Gloucester Old Spots. Thus it can be inferred that endogenous noradrenaline is responsible for promoting leanness in a pig breed with known sympathetic overactivity.

Animals↗

Autonomic responsiveness in stress-sensitive and stress-resistant pigs.

The responsiveness of the autonomic nervous system was studied in twenty-six 140 day old thiopentone anaesthetized lean stress-sensitive Pietrain (P) and fatter stress-resistant Gloucester (G) pigs, using the Valsalva like manoeuvre (VLM), and the i.v. tyramine, noradrenaline (NA) and phenylephrine tests. The heart rate responses to the VLM and tyramine tests were greater in P. The pressor response to NA was lower in P, and the change in heart rate per unit change in blood pressure-during phenylephrine infusion was the same in the two breeds. The sympathetic nervous system in P was, therefore, more responsive than that in G, and this was attributable to a higher pre-adrenoreceptor responsiveness in P. The potentially greater sympathetic responsiveness in stress-sensitive pigs could account for their greater leanness, their stress-induced metabolic acidosis, and for their susceptibility to myocardial failure.

Animals↗