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Biomedical subjects

Timothy P Murphy

Publications and source records attributed to Timothy P Murphy.

At least 19 recordsLinked to original sources
PubMed2006

Renal artery duplex ultrasonography as a screening and surveillance tool to detect renal artery stenosis: a comparison with current reference standard imaging.

OBJECTIVE: Digital subtraction angiography quantitative vessel analysis (QVA) to assess percent renal arterial stenosis (RAS) is the reference standard. Quantitative vessel analysis is not ideal for screening purposes. Renal artery duplex ultrasonography (RADUS) is a noninvasive method to screen for RAS using well-known parameters. We investigated the direct correlation between several RADUS parameters and QVA to evaluate the acceptability of RADUS as a RAS screening and surveillance tool. METHODS: We performed a multicenter retrospective study. Stenoses were evaluated in all patients with arteriograms and RADUS examinations within 30 days of each other in the span of 1 year. Percent stenosis of each stenotic renal artery segment was calculated digitally with QVA and correlated with the corresponding peak systolic velocity (PSV) and renal-aortic ratio (RAR) obtained with RADUS. Descriptive statistics and receiver operating characteristic curves were calculated. Correlation of percent stenosis, PSV, and RAR was performed. Sensitivity, specificity, and accuracy of diagnostic cut points for each RADUS parameter were calculated. RESULTS: Sixty-seven renal arteries were included. Thirty-three arteries had less than 60% stenosis; 34 had stenosis of 60% or greater. The mean values were PSV, 272.791 cm/s; RAR, 3.716; and angiographic percent stenosis, 51.731%. Receiver operating characteristic curves showed higher accuracy for RAR with stenoses of 60% or greater versus PSV. CONCLUSIONS: Renal artery duplex ultrasonographic parameters for 60% or greater RAS correlate well with QVA. For detecting stenosis of 60% or greater, RAR is the most accurate parameter at a threshold of 2.5. Renal-aortic ratio is more accurate than PSV. Peak systolic velocity may be a useful RADUS alternative parameter for hemodynamically important stenoses in the setting of aortic disease when aortic velocities are less than 40 or greater than 100 cm/s.

Angiography, Digital Subtraction↗
PubMed2005

Hydrolysis of conjugated metabolites of buprenorphine II. The quantitative enzymatic hydrolysis of norbuprenorphine-3-beta-D-glucuronide in human urine.

In gas chromatographic-mass spectroscopic analysis of buprenorphine metabolites, the urine specimen must be first hydrolyzed to release buprenorphine and norbuprenorphine from their glucuronide conjugates. For evaluation of existing hydrolysis methods and to find out the optimal hydrolysis conditions, buprenorphine-3-beta-D-glucuronide (B3G) and norbuprenorphine-3-beta-D-glucuronide (NB3G) were synthesized. In a previous communication we reported on the optimum conditions for hydrolysis of B3G. Because we have previously shown that no hydrolysis was achieved under basic conditions and that acid hydrolysis resulted in extensive degradation, only enzymatic hydrolysis was examined for NB3G. This study therefore reports on the optimum enzymatic conditions for the hydrolysis of NB3G. Urine fortified with synthetic NB3G was hydrolyzed with beta-glucuronidases from different source species, including Helix pomatia, Escherichia coli, and Patella vulgata. Glusulase, a preparation containing both the beta-glucuronidase (H. pomatia) and sulfatase, was also tested. It was found that marked differences exist in the reactivity of these enzymes. Incubation with glucuronidases from H. pomatia or E. coli at 37 degrees C for 16 h resulted in quantitative hydrolysis of NB3G. At 60 degrees C, complete hydrolysis was achieved with 1000 units of H. pomatia in 4 h and after only 1 h with glusulase. On the other hand, incubation at 60 degrees C for 4 h with Patella vulgata resulted in only 14.7% hydrolysis.

Animals↗
PubMed2005

Quality of life and exercise performance after aortoiliac stent placement for claudication.

PURPOSE: To determine the effect of aortoiliac stent placement on walking ability and health-related quality of life (QOL) for elderly individuals with moderate to severe intermittent claudication. MATERIALS AND METHODS: A prospective single-center study was performed in 35 consecutive patients (46 symptomatic limbs) with intermittent claudication and aortoiliac insufficiency (mean age+/-SD, 61.1 years+/-9.5). Baseline and follow-up data to 12 months included clinical status, ankle-brachial index (ABI), exercise performance according to a standardized treadmill exercise protocol, and self-reported health-related QOL according to the Walking Impairment Questionnaire (WIQ) and the Short Form 36 (SF-36). RESULTS: Comparing baseline with 12-month data, mean ABI significantly improved from 0.64+/-0.15 to 0.89+/-0.19 (P<.01). Similarly, mean initial claudication duration improved from 1.7 minutes+/-1.0 to 4.7 minutes+/-3.3 and maximum walking duration on the treadmill test improved from a mean of 3.3 minutes+/-1.8 to 8.7 minutes+/-4.4. All WIQ subscales showed significant improvement, and the SF-36 physical component scale as well as subscales of physical functioning, bodily pain, role physical, and vitality showed significant improvement. There was no 30-day mortality. Complications in the perioperative period that required treatment were observed in three patients (9%), but surgery was not required for any complications. Importantly, urgent or emergent surgery was not required for any complication and no permanent disability related to complications occurred. CONCLUSIONS: A high technical success rate (97%) and low complication rate were observed. Exercise performance and health-related QOL results improved significantly after stent placement. Revascularization with stent placement should be strongly considered in addition to conservative management for moderate to severe claudication with aortoiliac obstruction. A randomized clinical trial would be needed to gauge the relative effectiveness of stent implantation and conservative therapy.

Adult↗
PubMed2005

Clinical services provided by interventional radiologists to Medicare beneficiaries in the United States, 2000-2003.

To identify trends in Evaluation and Management (E&M) and non-E&M services of interventional radiologists (physician specialty type 94) from 2000 to 2003 for Medicare patients, Medicare Part B physician annual allowed services data from the Centers of Medicare and Medicaid Services (CMS) were analyzed for all interventional radiologists from 2000 to 2003. Because the number of interventional radiologists in the United States according to the Society of Interventional Radiology is, on average, 4.2 times the number of interventional radiologists who use physician specialty type 94, we extrapolated the E&M services for each year. During the period examined, the total number of E&M services by interventional radiologists increased 309%, from 9,698 in 2000 to 29,914 in 2003. The most commonly performed services were Office or Other Outpatient Visit (Current Procedural Terminology [CPT] codes 99211-99215) for established patients, followed by Subsequent Hospital Care (CPT 99231-99233) and Office or Other Outpatient Consultations (CPT 99241-99245). The extrapolated number of E&M services by interventional radiologists for Medicare patients in 2003 is approximately 107,853. The number of Office and Outpatient Visits for New Patients (CPT 99201-99205) increased 142%, whereas the number of Consultations for New Patients (CPT 99241-99245) increased 208%. The total number of codes reimbursed by CMS to interventional radiologists (type 94) increased from 2.8 million in 2000 to 3.8 million in 2003.

Current Procedural Terminology↗
PubMed2004

Analysis of the anthraquinones aloe-emodin and aloin by gas chromatography/mass spectrometry.

A procedure was developed for the determination of low levels of the anthraquinones aloe-emodin and aloin A (barbalin) in aloe products based on gas chromatography/mass spectrometry (GC/MS) of the trimethyl silyl (TMS) derivatives of these analytes in the presence of Chrysophanol used as internal standard. The method was used to analyze several aloe based commercial products (liquids, gels and solids). Wide variation in the level of these anthraquinones was observed among the different products. The method had a sensitivity of 0.005 ppm of aloe-emodin and 0.05 ppm of aloin.

Aloe↗
PubMed2004

Aortoiliac insufficiency: long-term experience with stent placement for treatment.

PURPOSE: To establish and report the authors' experience with the long-term outcomes of aortoiliac stent placement for treatment of chronic lower-extremity ischemia. MATERIALS AND METHODS: Stents were placed in 505 arterial segment lesions in 365 patients who presented with symptoms of chronic leg ischemia between February 1992 and March 2001. The 505 treated lesions were 88 occlusions and 417 stenoses. Indications for stent placement were claudication in 312 (62%), rest pain in 107 (21%), ulcer in 67 (13%), and gangrene in 19 (4%) arterial segments. Patients were followed up for up to 105 months (mean, 33 months +/- 27 [SD]). RESULTS: Hemodynamic success was achieved in 484 (98%) of the 496 limbs for which postprocedural translesion pressure gradients were available. Mean ankle-brachial indexes improved from 0.53 +/- 0.25 to 0.79 +/- 0.23 (P <.001). Major complications were seen in 24 (7%) patients. Two patients (0.5%) died within 30 days after stent placement. Twenty (6%) of 355 patients underwent aortic or iliac bypass surgery during the follow-up period. Eight years after stent placement, primary patency was 74%; primary assisted patency, 81%; and secondary patency, 84%. Variables associated with better patency included stenosis (rather than occlusion), shorter lesion length, older age, and limb-threatening ischemia. At the last follow-up examination, 74% of the 466 limbs for which follow-up clinical status data were available were asymptomatic, 22% were associated with claudication, 3% were associated with rest pain, and 1% were associated with ischemic tissue loss. Five patients underwent amputation on the ipsilateral side after stent placement. CONCLUSION: Findings from long-term experience with aortoiliac stent placement for treatment of chronic lower-extremity ischemia confirmed the procedure to be a durable, low-risk revascularization option.

Aged↗
PubMed2004

Increase in utilization of percutaneous renal artery interventions by medicare beneficiaries, 1996-2000.

OBJECTIVE: Our purpose was to review data from Medicare physician claims to ascertain differences in annual volumes of renal artery interventions versus surgery and differences in utilization of renal artery interventions among geographic regions according to physician provider type between 1996 and 2000. MATERIALS AND METHODS: We analyzed claims submitted to Medicare in 1996, 1998, and 2000 and extracted claims for renal artery angioplasty, stent placement, or bypass surgery. Analyses were performed for percutaneous renal artery interventions categorized by Centers for Medicare & Medicaid Services (CMS) geographic region and physician provider type. RESULTS: Between 1996 and 2000, the total volume of renal revascularization (surgical and percutaneous) increased 62%, from 13,380 to 21,660 procedures. The annual volume of renal artery surgery decreased 45% in 2000, compared with the volume in 1996. Annual volumes of renal artery angioplasty and stent placement increased 2.4-fold in 2000 compared with those in 1996. Most growth in percutaneous renal artery interventions is attributed to added provision by cardiologists, who increased their annual volume 3.9-fold. More than a threefold difference in rates of use of renal artery interventional procedures across CMS regions was found. In the Southeast region, the volume of renal artery interventions by cardiologists increased more than 15-fold. CONCLUSION: Among Medicare beneficiaries, the volume of percutaneous renal artery interventions is increasing rapidly, whereas the volume of renal artery surgery is declining. Most growth in percutaneous renal artery revascularization is attributed to increased performance by cardiologists; explosive growth in annual procedure volume by cardiologists occurred in some regions. Marked disparity in use among CMS regions was found.

Angioplasty, Balloon↗
PubMed2002

Chronic renal ischemia: pathophysiologic mechanisms of cardiovascular and renal disease.

Chronic renal ischemia caused by renal artery stenosis (RAS) elicits a complex biologic response. Although the traditional pathophysiologic pathways underlying renal ischemia have been well studied, there is emerging evidence that additional mechanisms may be responsible for producing many of the hemodynamic alterations and end-organ injury seen in patients with RAS, including persistent hypertension, renal insufficiency, and cardiac disturbance syndromes. A better understanding of these mechanisms may allow earlier identification of RAS, provide markers to predict the response to revascularization, or allow unique therapeutic targets for drug development. This and a subsequent article will explore the pathophysiologic and clinical implications of chronic renal ischemia.

Cardiovascular Diseases↗
PubMed2002

Chronic renal ischemia: implications for cardiovascular disease risk.

Chronic renal ischemia caused by atherosclerotic renal artery stenosis (RAS) is gaining recognition as a potentially important risk factor for cardiovascular (CV) morbidity and mortality. The etiology of increased risk of CV events is multifaceted and includes direct physiologic changes that increase risk as well as intermediate clinical effects that are associated with worse outcome. Physiologic changes associated with increased CV risk in patients with RAS include increased production of fibrogenic and vasoactive peptides such as renin, angiotensin, endothelin, and catecholamines, as well as endothelial cell dysfunction. Clinical intermediate conditions associated with higher incidences of CV events seen in patients with renal ischemia include hypertension, systemic atherosclerosis, chronic renal failure, and left ventricular hypertrophy and dysfunction. More thorough understanding of the myriad physiologic changes seen in patients with RAS will likely improve patient selection for renal artery revascularization. Clinical trials should examine a full range of CV and renal outcomes, not just blood pressure, to adequately assess the merits of revascularization.

Chronic Disease↗