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Biomedical subjects

J A O'Brien

Publications and source records attributed to J A O'Brien.

107 records · Page 6Linked to original sources

Diabetes in Canada: direct medical costs of major macrovascular complications.

OBJECTIVES: To estimate direct medical costs of managing major macrovascular complications in diabetic patients. METHODS: Costs were estimated for acute myocardial infarction (AMI) and ischemic stroke by applying unit costs to typical resource use profiles. Data were obtained from many Canadian sources, including the Ontario Case Cost Project, provincial physician and laboratory fee schedules, provincial formularies, government reports, and peer-reviewed literature. For each complication, the event costs per patient are those associated with resource use specific to the acute episode and any subsequent care occurring in the first year. State costs are the annual costs per patient of continued management. All costs are expressed in 1996 Canadian dollars. RESULTS: Acute hospital care accounts for approximately half of the first year management costs ($15,125) of AMI. Given the greater need for postacute care, acute hospital care has less impact (28%) on event costs for stroke ($31,076). The state costs for AMI and stroke are $1544 and $8141 per patient, respectively. CONCLUSIONS: Macrovascular complications of diabetes potentially represent a substantial burden to Canada's health care system. As new therapies emerge that may reduce the incidence of some diabetic complications, decision makers will need information to make critical decisions regarding how to spend limited health care dollars. Published literature lacks Canadian-specific cost estimates that may be readily translated into patient-level cost inputs for an economic model. This paper provides two key pieces of the many needed to understand the scope of the economic burden of diabetes and its complications for Canada.

Adult↗

Bileaflet valve replacement: complications and costs.

A meta-analysis of the available literature on the CarboMedics and St. Jude Medical valves was conducted to compare their clinical performance. Frequency of valve-related complications for aortic, mitral, and double-valve replacements served as a measure of performance. An economic model was created to estimate the economic impact of valve-related complications. Overall, fewer events occurred with the St. Jude Medical valve than with the CarboMedics valve. As a result, use of the St. Jude Medical valve is expected to save up to $13,201 over 10 years.

Adolescent↗

Metabolism of a new HIV-1 reverse transcriptase inhibitor, 3-[2-(benzoxazol-2-yl)ethyl]-5-ethyl-6-methylpyridin-2(1H)-one (L-696,229), in rat and liver slices.

L-696,229 is a potent and specific inhibitor of human immunodeficiency virus type 1 (HIV-1) reverse transcriptase and is currently undergoing clinical evaluation. In vivo metabolism in rats was investigated using an intravenous bolus dose of 5 mg/kg [3H]L-696,229. The amount of radioactivity eliminated in bile and urine over a period of 6 hr was 60 and 22%, respectively. Radiochromatographic analysis of the bile and urine showed that L-696,229 was metabolized rapidly and completely to several common metabolites. Sequential oxidation at the alpha-position of the 5-ethyl group to an acetyl moiety, aromatic hydroxylation of the benzoxazole group (position C4', C6', or C7'), and subsequent sulfate conjugation were the major metabolic pathways as determined by the application of enzymatic hydrolysis, FAB-MS, and 1H- and 13C-NMR spectroscopies. The in vitro metabolism of this 2-pyridinone derivative with rat liver slices resulted primarily in hydroxylation at the 6-methyl and 5-ethyl groups. The 6-hydroxymethyl- and 5-alpha-hydroxyethyl analogs were also inhibitors of HIV-1 reverse transcriptase.

Animals↗

Metabolism of 3-[2-(benzoxazol-2-yl)ethyl]-5-ethyl-6-methylpyridin-2 (1H)-one (L-696,229), an HIV-1 reverse transcriptase inhibitor, by rat liver slices and in humans.

Healthy subjects were administered single oral doses of 800 mg or 400 mg 3-[2-(benzoxazol-2-yl)ethyl]-5-ethyl-6-methylpyridin-2(1H)-o ne (L-696,229), a nonnucleoside inhibitor of the human immunodeficiency virus-type 1 (HIV-1) reverse transcriptase (RT). Plasma or urine samples were collected over a period of 48 hr. Pooled plasma (0.5-6 hr) and urine (0-24 hr) samples were analyzed by HPLC-UV and HIV-1 RT inhibition assay using poly rC.dG as a template primer. The parent compound and several common metabolites were detected in both samples. The metabolic profiles were also similar to those obtained from a rat liver slice incubation with [3H]L-696,229. The in vitro metabolites were identified by NMR and MS as 5 alpha-hydroxyethyl- (major), 5,6-dihydrodiol-, 6'-hydroxy-, 6-hydroxymethyl-, and 5-vinyl analogs, and a benzoxazole ring hydrolysis product. Most of the significant metabolites in human plasma and urine were found to be identical to the in vitro metabolites, as established by HPLC-UV and MS. Hydrolysis of the plasma and urine with beta-glucuronidase/sulfatase indicated the presence of significant amounts of conjugates of the parent compound and 5 alpha-hydroxyethyl metabolite. Most of the other primary metabolites were also present in conjugated forms, albeit in small quantities. In addition, two secondary metabolites were isolated and identified from the hydrolyzed urine as 5-acetyl-6'-hydroxy- and 5 alpha-hydroxyethyl-6-hydroxymethyl- analogs.(ABSTRACT TRUNCATED AT 250 WORDS)

Administration, Oral↗

Altered renovascular resistance after spontaneous recovery from hemolytic uremic syndrome.

Twenty-three patients were evaluated from 1-15 (mean 6) years after recovering from an episode of diarrhea-associated associated childhood hemolytic uremic syndrome (DA-HUS). All patients had received only conservative treatment; none had been given experimental, anti-coagulant, or immunological therapies. Follow-up studies included morphologic and duplex Doppler sonograms. Doppler sonography was used to determine the resistive index, a measure of renovascular resistance. Histories and physical examinations revealed no abnormalities. Results of laboratory studies, which included calculated glomerular filtration rates, were all within normal limits, except for one patient with minor urinary abnormalities. Renal sonograms showed no significant abnormalities of kidney length or parenchymal appearance. However, Doppler sonographic examinations revealed that the DA-HUS patients demonstrated less of a decrease in renovascular resistance with age than did the control group (p < 0.0002). After recovery, patients treated exclusively with conservative management during an acute episode of DA-HUS appeared to have an excellent long-term prognosis. Comparison of our results with those from other studies in which investigational therapies have been used during the acute phase of DA-HUS suggests that latent toxicities which cause long term sequelae may not have been appreciated previously. The clinical significance of the altered renal vascular resistance remains to be delineated.

Acute Disease↗

Biotransformation of 5-chloro-3-phenylthioindole-2-carboxamide (L-734,005) in rhesus monkeys and rat liver microsomes to a potent HIV-1 reverse transcriptase inhibitor.

Rhesus monkeys were dosed orally with 10 mg/kg 5-chloro-3-phenylthioindole-2-carboxamide (L-734,005), a nonnucleoside human immunodeficiency virus type 1 (HIV-1) reverse transcriptase inhibitor, in polyethylene glycol 300. Plasma samples from these monkeys demonstrated greater bioactivity in an HIV-1 reverse transcriptase inhibition assay than anticipated from the parent compound concentrations as determined by an HPLC-UV assay. One major and three minor metabolites, as well as the parent compound, were detected in the plasma. One of the minor metabolites was determined to be several-fold more active, and the major metabolite one-half as active as the parent compound in the inhibition assay. Identical metabolites were formed during an incubation of L-734,005 with rat liver microsomes. The most active minor metabolite was identified as a sulfone analog (L-737,126) of the parent compound by NMR and MS analyses. The less active major metabolite and two relatively inactive minor metabolites were similarly identified as the sulfoxide, 4-hydroxythiophenyl and 6-hydroxyindole analogs of L-734,005. The synthetic sulfone analog was highly potent against HIV-1, with a 95% inhibitory concentration of 3.0 nM for the spread of virus infection in a cell culture.

Animals↗