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Biomedical subjects

Michael Hayes

Publications and source records attributed to Michael Hayes.

At least 19 recordsLinked to original sources

Determination of N-methyl-4-isoleucine-cyclosporin (NIM811) in human whole blood by high performance liquid chromatography-tandem mass spectrometry.

A liquid chromatographic method with tandem mass spectrometric detection (LC-MS/MS) for the determination of N-methyl-4-isoleucine-cyclosporin (NIM811) was developed and validated over the concentration range 1-2500 ng/mL in human whole blood using a 0.05 mL sample volume. NIM811 and the internal standard, d(12)-cyclosporin A (d(12)-CsA), were extracted from blood using MTBE via liquid-liquid extraction. After evaporation of the organic solvent and reconstitution, a 10 microL aliquot of the resulting extract was injected onto the LC-MS/MS system. Chromatographic separation of NIM811 and internal standard was performed using a Waters Symmetry RP-8 (50 x 4.6 mm, 3 microm particle size) column. The mobile phase consists of 10 mm ammonium acetate in water (A) and acetonitrile (B), with 45% B from 0 to 0.2 min, 45 to 85% B from 0.2 to 0.8 min and 85% B from 0.8 to 2.2 min. The total run time was 3.5 min with a flow rate of 0.8 mL/min. The method was validated for sensitivity, linearity, reproducibility, stability, dilution integrity and recovery. The precision and accuracy of quality control samples at low (2.00 ng/mL), medium (20.0 and 400 ng/mL) and high (2000 ng/mL) concentrations were in the range 1.1-4.3% relative standard deviation (RSD) and -2.5-10.0% (bias), respectively, from three validation runs. The method has been used to measure the exposure of NIM811 in human subjects.

Area Under Curve↗

Contributions of age and alcohol consumption to cerebellar integrity, gait and cognition in non-demented very old individuals.

Gait disturbance and cognitive changes are common with ageing. The cerebellum contributes to motor coordination and participates in various aspects of cognition. However, no research has investigated the possible cerebellar contribution to gait and cognition in non-demented very old individuals. The current study aimed to determine the associations between indices of cerebellar size (vermal area and total volume) and measures of motor and cognitive integrity, as well as the role of variables known to impact on cerebellar size (alcohol consumption and chronological age) in a sample of 111 community dwellers (mean age: 85 years; range: 81-97 years). A marginally significant association was present between age and total vermal area. Significant correlations between current daily alcohol intake and some vermal areas were observed. These associations were more pronounced in men, particularly after controlling for cerebrum size. Multiple linear regression models revealed limited unique contributions of cerebellar predictors to neurological and cognitive measures. In summary, the results indicate that the cerebellum may be susceptible to alcohol-related shrinkage in non-demented very old individuals, more so in men, even at low dose. It also appears that the observed changes in cerebellum size in this population contribute little to neurological and cognitive changes.

Age Factors↗

Phase I/II study of imatinib mesylate for recurrent malignant gliomas: North American Brain Tumor Consortium Study 99-08.

PURPOSE: Phase I: To determine the maximum tolerated doses, toxicities, and pharmacokinetics of imatinib mesylate (Gleevec) in patients with malignant gliomas taking enzyme-inducing antiepileptic drugs (EIAED) or not taking EIAED. Phase II: To determine the therapeutic efficacy of imatinib. EXPERIMENTAL DESIGN: Phase I component used an interpatient dose escalation scheme. End points of the phase II component were 6-month progression-free survival and response. RESULTS: Fifty patients enrolled in the phase I component (27 EIAED and 23 non-EIAED). The maximum tolerated dose for non-EIAED patients was 800 mg/d. Dose-limiting toxicities were neutropenia, rash, and elevated alanine aminotransferase. EIAED patients received up to 1,200 mg/d imatinib without developing dose-limiting toxicity. Plasma exposure of imatinib was reduced by approximately 68% in EIAED patients compared with non-EIAED patients. Fifty-five non-EIAED patients (34 glioblastoma multiforme and 21 anaplastic glioma) enrolled in the phase II component. Patients initially received 800 mg/d imatinib; 15 anaplastic glioma patients received 600 mg/d after hemorrhages were observed. There were 2 partial response and 6 stable disease among glioblastoma multiforme patients and 0 partial response and 5 stable disease among anaplastic glioma patients. Six-month progression-free survival was 3% for glioblastoma multiforme and 10% for anaplastic glioma patients. Five phase II patients developed intratumoral hemorrhages. CONCLUSIONS: Single-agent imatinib has minimal activity in malignant gliomas. CYP3A4 inducers, such as EIAEDs, substantially decreased plasma exposure of imatinib and should be avoided in patients receiving imatinib for chronic myelogenous leukemia and gastrointestinal stromal tumors. The evaluation of the activity of combination regimens incorporating imatinib is under way in phase II trials.

Adolescent↗

Anticipation of onset age in familial Parkinson's disease without SCA gene mutations.

Assessment of a series of 279 cases with Lewy body disease revealed 14 families having a family history consistent with autosomal dominant inheritance, eight of these with dominant Parkinsonism and six with dominant dementia. Analysis of the age at onset and genetic features in these families revealed significant anticipation only in a subset of parkinsonian families, with no pathological alleles for spinocerebellar ataxias or the common alpha-synuclein or LRRK2 point mutations.

Age of Onset↗

Sphingosine kinase 1-mediated inhibition of Fas death signaling in rheumatoid arthritis B lymphoblastoid cells.

OBJECTIVE: It is becoming increasingly apparent that B cells play an important role in the pathogenesis of rheumatoid arthritis (RA). Due to the scarcity of B cells in RA, it has been technically difficult to functionally characterize B cell apoptosis in this disease. As a necessary first step to identify candidate aberrations, we investigated Fas-mediated signaling events in immortalized peripheral blood B lymphoblastoid cell lines (LCLs) from patients with RA and controls. METHODS: Cell death was determined by the MTS assay, and apoptosis was detected by the TUNEL assay and DNA laddering. Proteolytic activation of caspase 3 was determined by immunoblotting, and its enzymatic activity was determined by a fluorometric technique. Messenger RNA (mRNA) expression was quantified by real-time polymerase chain reaction (PCR) analysis. The functional role of sphingosine kinase (SPHK) was determined by measuring its enzymatic activity, by quantifying the levels of its product, sphingosine 1-phosphate (S1P), and by investigating the ability of the SPHK inhibitor N,N-dimethylsphingosine and isozyme-specific small interfering RNA (siRNA) oligonucleotides to reverse signaling aberrations. RESULTS: LCLs from patients with RA displayed disease-specific Fas-mediated signal transduction impairment with consequent resistance to cell death. RA LCLs displayed high constitutive SPHK activity and increased levels of S1P. Real-time PCR analysis showed higher SPHK-1 mRNA expression levels in RA patients compared with paired controls. Increased SPHK-1 (but not SPHK-2) mRNA levels were observed in synovial tissue from RA patients. Competitive inhibitors of SPHK reversed the resistance of RA LCLs to Fas-induced apoptosis. Additionally, resistance to Fas-mediated signaling was reversed by siRNA oligonucleotides specific for SPHK-1 but not by oligonucleotides specific for SPHK-2. CONCLUSION: These findings demonstrate disease-specific resistance to Fas-mediated death signaling in patients with RA and implicate increased SPHK-1 activity as the cause of this aberration.

Adaptor Proteins, Signal Transducing↗

Cognitive, extrapyramidal, and magnetic resonance imaging predictors of functional impairment in nondemented older community dwellers: the Sydney Older Person Study.

OBJECTIVES: To identify the clinical correlates of functional incapacity in the community living "old-old." DESIGN: Cross-sectional. SETTING: Community-based. PARTICIPANTS: One hundred six nondemented people aged 80 to 94. MEASUREMENTS: Participants were medically and cognitively assessed, underwent magnetic resonance imaging scanning (MRI), and were interviewed regarding their functional status: activities of daily living (ADLs), instrumental ADLs (IADLs), and the complex IADL functions of reading, hobbies, and socializing. RESULTS: Dependency in IADLs, but not ADLs, was present. After controlling for age, sex, and education, extrapyramidal (EP) signs were significantly associated with two of the three IADLs, with EP signs comprising a composite score of 10 EP signs (e.g., resting tremor) and a 5-meter timed walk. Cognitive test performance on a range of tests was also associated with functional status. A hierarchical model confirmed the association between the EP signs and cognitive test performance and functional scores, but no "pattern" of cognitive association emerged. Hippocampal volume was associated with socializing. CONCLUSION: This study has shown that many nondemented very old people living in the community are losing capacity to perform IADL functions and that areas of incapacity are associated with the presence of EP signs and impaired cognition. These results highlight the need for health workers to include an assessment of EP and cognitive status in their evaluation of older persons living in the community, even in the context of a lack of dementia diagnosis. Furthermore, it signifies the need to directly evaluate IADL function to identify need for intervention and support if required. This group of old-old individuals may now be considered the "survivors" of their cohort, and early detection of the difficulties they are experiencing will enable clinicians to respond appropriately, thus providing them a higher quality of life for their years to come.

Activities of Daily Living↗

Do guidelines matter? Implementation of the ACG and AGA osteoporosis screening guidelines in inflammatory bowel disease (IBD) patients who meet the guidelines' criteria.

OBJECTIVE: The American College of Gastroenterology (ACG) and American Gastroenterology Association (AGA) have both recently issued guidelines (the "Guidelines") regarding the diagnosis and management of osteoporosis in patients with inflammatory bowel disease (IBD). The objective of this study was to determine the yield of implementing the Guidelines' recommendations in a prospective cohort of IBD patients and identify the prevalence of bone loss, risk factors, and potential influence on management. METHODS: One hundred consecutive IBD patients who fulfilled the Guidelines' criteria underwent dual energy X-ray absorptiometry scanning (DEXA) scanning of the lumbar vertebrae and bilateral hips. Demographic data, risk factor information, and changes in therapy based on screening were collected and analyzed. RESULTS: Indications for screening were history of prolonged past or concurrent steroid use (92%), postmenopausal status (7%), and history of low trauma fracture (7%). Forty-four percent of patients had osteopenia of either the lumbar spine or the hips, 12% had osteoporosis of either the spine or hips, and 44% had normal bone density. In a univariate analysis, factors predicting a greater likelihood of osteoporosis (but not osteopenia) were a diagnosis of Crohn's disease (vs. ulcerative colitis), low body mass index in women, and postmenopausal status. Specific therapies based on DEXA findings were initiated in 69% of patients: oral calcium and vitamin D supplementation in 69% and an oral bisphoshphonate in 20%. CONCLUSIONS: Implementation of the Guidelines led to the detection of osteopenia or osteoporosis and initiation of specific therapies in a majority of patients who met the Guidelines' criteria for DEXA screening.

Absorptiometry, Photon↗

Metabolism and disposition of imatinib mesylate in healthy volunteers.

Imatinib mesylate (GLEEVEC, GLIVEC, formerly STI571) has demonstrated unprecedented efficacy as first-line therapy for treatment for all phases of chronic myelogenous leukemia and metastatic and unresectable malignant gastrointestinal stromal tumors. Disposition and biotransformation of imatinib were studied in four male healthy volunteers after a single oral dose of 239 mg of (14)C-labeled imatinib mesylate. Biological fluids were analyzed for total radioactivity, imatinib, and its main metabolite CGP74588. Metabolite patterns were determined by radio-high-performance liquid chromatography with off-line microplate solid scintillation counting and characterized by liquid chromatography-mass spectrometry. Imatinib treatment was well tolerated without serious adverse events. Absorption was rapid (t(max) 1-2 h) and complete with imatinib as the major radioactive compound in plasma. Maximum plasma concentrations were 0.921 +/- 0.095 mug/ml (mean +/- S.D., n = 4) for imatinib and 0.115 +/- 0.026 mug/ml for the pharmacologically active N-desmethyl metabolite (CGP74588). Mean plasma terminal elimination half-lives were 13.5 +/- 0.9 h for imatinib, 20.6 +/- 1.7 h for CGP74588, and 57.3 +/- 12.5 h for (14)C radioactivity. Imatinib was predominantly cleared through oxidative metabolism. Approximately 65 and 9% of total systemic exposure [AUC(0-24 h) (area under the concentration time curve) of radioactivity] corresponded to imatinib and CGP74588, respectively. The remaining proportion corresponded mainly to oxidized derivatives of imatinib and CGP74588. Imatinib and its metabolites were excreted predominantly via the biliary-fecal route. Excretion of radioactivity was slow with a mean radiocarbon recovery of 80% within 7 days (67% in feces, 13% in urine). Approximately 28 and 13% of the dose in the excreta corresponded to imatinib and CGP74588, respectively.

Adult↗

State-to-state dynamics of high-n Rydberg H-atom scattering with D2.

Full quantum-state resolved scattering of a highly excited Rydberg H atom with D2 has been carried out using the Rydberg H-atom time-of-flight method. A detailed analysis of the experimental results shows that both inelastic and reactive scatterings are significant in the Hn-D2 collisions, and nuclear spin is conserved in the inelastic scattering process. The differential cross sections for the Hn-D2 reaction measured in this work are then compared with the results for the H+ reaction with D2 in an ion beam scattering experiment. The remarkable agreement between the two experiments suggests that the Fermi independent-collider model is valid even at the full quantum state-to-state scattering level, providing a promising tool for investigating the state-to-state dynamics of certain elementary ion-molecule reactions.

Journal Article↗

Pharmacokinetic interaction between ketoconazole and imatinib mesylate (Glivec) in healthy subjects.

The study under discussion was a drug-drug interaction study in which the effect of ketoconazole, a potent CYP450 3A4 inhibitor, on the pharmacokinetics of Glivec (imatinib) was investigated. A total of 14 healthy subjects (13 male, 1 female) were enrolled in this study. Each subject received a single oral dose of imatinib 200 mg alone, and a single oral dose of imatinib 200 mg coadministered with a single oral dose of ketoconazole 400 mg according to a two-period crossover design. The treatment sequence was randomly allocated. Subtherapeutic imatinib doses and a short exposure were tested in order not to overexpose the healthy volunteers. There was a minimum 7-day washout period between the two sequences. Blood samples for determination of plasma concentrations were taken up to 96 h after dosing. Imatinib and CGP74588 (main metabolite of imatinib) concentrations were measured using LC/MS/MS method and pharmacokinetic parameters were estimated by a non-compartmental analysis. Following ketoconazole coadministration, the mean imatinib C(max), AUC((0-24)) and AUC((0- infinity )) increased significantly by 26% ( P<0.005), 40% ( P<0.0005) and 40% ( P <0.0005), respectively. There was a statistically significant decrease in apparent clearance (CL/f) of imatinib with a mean reduction of 28.6% ( P<0.0005). The mean C(max) and AUC((0-24)) of the metabolite CGP74588 decreased significantly by 22.6% ( P<0.005) and 13% ( P<0.05) after ketoconazole treatment, although the AUC((0- infinity )) of CGP74588 only decreased by 5% ( P=0.28). Coadministration of ketoconazole and imatinib caused a 40% increase in exposure to imatinib in healthy volunteers. Given its previously demonstrated safety profile, this increased exposure to imatinib is likely to be clinically significant only at high doses. This interaction should be considered when administering inhibitors of the CYP3A family in combination with imatinib.

Adult↗

Pharmacokinetics and pharmacodynamics of imatinib in a phase I trial with chronic myeloid leukemia patients.

PURPOSE: To evaluate the basic pharmacokinetic (PK) characteristics of imatinib mesylate and assess the relationship between the PK and pharmacodynamic (PD) properties of the drug. PATIENTS AND METHODS: The PK and PD properties of imatinib were investigated during a phase I trial that included 64 adult patients with Philadelphia chromosome-positive leukemias. Patients received imatinib orally once or twice daily. PK parameters of imatinib, derived from the plasma concentration-time curves, were determined. PD response, defined as the WBC after 1 month of treatment with imatinib, was used to develop an efficacy model. A maximum inhibition-effect model was used to describe the relationship between reduction in WBC and drug exposure parameters. RESULTS: Imatinib exposure was dose proportional after oral administration for the dose range of 25 to 1,000 mg. There was a 1.5- to three-fold drug accumulation after repeated once-daily dosing. Mean plasma trough concentration was 0.57 microg/mL (approximately 1 micromol/L) 24 hours after administration of 350 mg of imatinib at steady-state, which exceeds the 50% inhibitory concentration required to inhibit proliferation of Bcr-Abl-positive leukemic cells. Analysis of PK/PD relationships indicates that the initial hematologic response depends on the administered dose for patients with chronic myeloid leukemia. CONCLUSION: Drug exposure (area under the concentration-time curve) is dose proportional for the dose range of 25 to 1,000 mg, and there is a 1.5- to three-fold drug accumulation at steady-state after once-daily dosing. Analysis of the relationship between PD (WBC reduction) and PK parameters at steady-state indicates that a dose of 400 mg or greater is required for maximal PD effect.

Administration, Oral↗

Attenuation of neointimal vascular smooth muscle cellularity in atheroma by plasminogen activator inhibitor type 1 (PAI-1).

Rupture of vulnerable atheroma often underlies acute coronary syndromes. Vulnerable plaques exhibit a paucity of vascular smooth muscle cells (VSMCs) in the cap. Therefore, decreased VSMC migration into the neointima may predispose to vulnerability. The balance between cell surface plasminogen activator activity and its inhibition [mediated primarily by plasminogen activator inhibitor type 1 (PAI-1)] modulates migration of diverse types of cells. We sought to determine whether increased expression of PAI-1 would decrease migration of VSMCs in vitro and neointimal cellularity in vivo in apolipoprotein E knockout (ApoE(-/-)) mice fed a high-fat diet. Increased vessel wall expression of PAI-1 in transgenic mice was induced with the SM22alpha promoter. VSMC migration through Matrigel in vitro was quantified with laser scanning cytometry. Expression of PAI-1 was increased threefold in the aortic wall of SM22-PAI transgene-positive mice. Neointimal cellularity of vascular lesions was decreased by 26% (p=0.01; n=5 each) in ApoE(-/-) mice with the SM22-PAI transgene compared with ApoE(-/-) mice. VSMCs explanted from transgene-positive mice exhibited twofold greater expression of PAI-1 and their migration was attenuated by 27% (p=0.03). Accordingly, increased expression of PAI-1 protein by VSMCs reduces their migration in vitro and their contribution to neointimal cellularity in vivo.

Animals↗

Identifying the pattern of olfactory deficits in Parkinson disease using the brief smell identification test.

BACKGROUND: Selective olfactory deficits occur in 70% to 90% of patients with Parkinson disease, independent of disease severity and duration. Olfactory testing may be a useful diagnostic aid for Parkinson disease, but the types of odors most commonly affected need to be identified. OBJECTIVE: To determine the pattern and types of odors affected in Parkinson disease by means of the University of Pennsylvania 12-item Brief Smell Identification Test (B-SIT; Sensonics, Inc, Haddon Heights, NJ). DESIGN: Testing patients with Parkinson disease and control subjects in 5 movement disorder clinics. PARTICIPANTS: Forty-nine nondemented patients with Parkinson disease and 52 age- and sex-matched controls. MAIN OUTCOME MEASURES: Normal or abnormal olfactory function was determined in each subject according to predetermined age and sex norms. Predictive statistics and discriminant function analyses were performed to determine the pattern and types of odors best discriminating patients from controls. RESULTS: Abnormal olfactory function was present in 40 (82%) of patients compared with 12 (23%) of controls. The B-SIT score was unaffected by smoking behavior, disease duration, or severity. The sensitivity of the B-SIT for Parkinson disease was 0.82, with a specificity and predictive value of 0.82 and 0.77, respectively. Only 5 of the 12 B-SIT odors (gasoline, banana, pineapple, smoke, and cinnamon) were required to adequately discriminate patients with Parkinson disease from controls. CONCLUSIONS: With the use of the B-SIT, 5 specific odors appear primarily affected in patients with Parkinson disease. Significantly, the ability of patients to detect some odors was unimpaired compared with that of controls. Better diagnostic aids could be developed on the basis of the selective pattern of hyposmia observed in Parkinson disease.

Adult↗

Short-term outcomes after brief ambulatory opioid detoxification with buprenorphine in young heroin users.

AIMS: This study examines the outcomes at 1, 3 and 6 months after a very brief outpatient detoxification with buprenorphine in 18-25-year-old heroin users. DESIGN: Prospective follow-up study. SETTING: Outpatient drug treatment clinic, providing brief detoxification in downtown Baltimore, Maryland, USA. PARTICIPANTS: One hundred and twenty-three subjects between 18 and 25 years old; 56% male; 95% Caucasian; seeking detoxification; living in Baltimore City and five surrounding counties. INTERVENTION: Detoxification with buprenorphine over 3 days. Follow-up at 1, 3 and 6 months. MEASUREMENTS: Drug use history, the Addiction Severity Index at baseline and follow-up, urine drug screens, evaluation of the detoxification experience. FINDINGS: By self-report, 37% of the total sample were not currently using heroin at 1 month, 32% at 3 months and 29% at 6 months, and 6.7%, 10.1% and 11.8% had an opioid negative urine test at 1, 3 and 6 months, respectively. There was a significant reduction from the baseline in mean Addiction Severity Index drug use composite score, as well as the mean number of days of heroin and cocaine use during past 30 days, that was sustained over the three follow-up points. Engagement in aftercare was generally poor. CONCLUSIONS: The findings show a reduced frequency and intensity of drug use, suggesting a possible role for brief outpatient detoxification in reducing the severity of dependence for some younger heroin users who may not yet be ready to engage in long-term abstinence-oriented or opioid substitution treatments.

Adolescent↗

Distribution of STI-571 to the brain is limited by P-glycoprotein-mediated efflux.

The adequate distribution of STI-571 (Gleevec) to the central nervous system (CNS) is critical for its effective use in CNS tumors. P-glycoprotein-mediated efflux in the blood-brain barrier may play a role in the CNS delivery of this drug. Whether STI-571 is a substrate of P-glycoprotein was determined by examining the directional flux of [(14)C]STI-571 in parental and MDR1-transfected Madin-Darby canine kidney (MDCK) II epithelial cell monolayers. The basolateral-to-apical flux of STI-571 was 39-fold greater than the apical-to-basolateral flux in the MDR1-transfected cells and 8-fold greater in the parental cell monolayers. This difference in directional flux was significantly reduced by a specific P-glycoprotein inhibitor (2R)-anti-5-[3-[4-(10,11-difluoromethanodibenzo-suber-5-yl)piperazin-1-yl]-2-hydroxypropoxy]quinoline trihydrochloride (LY335979). The role of P-glycoprotein in the CNS distribution of STI-571 was examined in vivo, using wild-type and mdr1a/b (-/-) knockout mice that were orally administered 25 mg/kg [(14)C]STI-571. In the wild-type mice, the brain-to-plasma STI-571 concentration ratio at all time points was low (1-3%); however, there was an 11-fold greater brain partitioning of STI-571 at 1 h postdose in the mdr1a/b (-/-) mice compared with the wild-type mice. When 12.5 mg/kg STI-571 was given intravenously, the brain-to-plasma ratio of STI-571 in the mdr1a/b (-/-) mice was approximately 7-fold greater than that of wild-type mice up to 120 min postdose. These data indicate that STI-571 is a substrate of P-glycoprotein, and that the inhibition of P-glycoprotein affects the transport of STI-571 across MDCKII monolayers. Moreover, P-glycoprotein plays an important role in limiting the distribution of STI-571 to the CNS.

ATP Binding Cassette Transporter, Subfamily B, Mem↗

A multicenter randomized evaluation of methadone medical maintenance.

Methadone medical maintenance (MMM) is a rational, cost-effective method to match treatment intensity to level of needed services. In the present study, 73 highly stable methadone maintenance patients were randomly assigned to either a routine methadone treatment, MMM--a once monthly reporting schedule--at the methadone maintenance program or MMM at a physician office. A 'stepped care' intensified treatment approach was used for patients who had drug-positive urine specimens or failed the medication recall procedure. Patients left two urine specimens for analysis each month (at least one on a random basis) and responded to one medication recall each month. Results are presented for the first 6 months of the 1-year trial. Only 1% of urine specimens were positive for illicit drugs, there was no evidence of methadone diversion and there were very low rates of medication misuse, with no between group differences. MMM patients initiated more new employment or family/social activities than the routine care patients. MMM patients were more satisfied with their treatment than the routine treatment patients, but all patients rated themselves satisfied or very satisfied with their treatment. Stepped care was well-tolerated and helped match patients to an appropriate intensity of service. The good outcomes observed with the present sample suggest that MMM can be implemented effectively as part of a continuum of care in clinic and office-based sites.

Adult↗