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Biomedical subjects

D J Cohen

Publications and source records attributed to D J Cohen.

At least 73 records · Page 4Linked to original sources
PubMed2000

Adequacy of intracoronary versus intravenous adenosine-induced maximal coronary hyperemia for fractional flow reserve measurements.

BACKGROUND: Fractional flow reserve (FFR) is a measure of coronary stenosis severity that is based on pressure measurements obtained at maximal hyperemia. The most widely used pharmacologic stimulus for maximal coronary hyperemia is adenosine, administered either as a continuous intravenous (IV) infusion or intracoronary (IC) bolus. IV adenosine has more side effects and is more costly than IC adenosine but has a more stable and prolonged hyperemic effect. METHODS: We compared the efficacy of IC and IV adenosine administration for the measurement of FFR in a multicenter trial. Fifty-two patients with 60 lesions underwent determination of FFR with both IV and IC adenosine. IV adenosine was administered as a continuous infusion at a rate of 140 microgram/kg per minute until a steady state hyperemia was achieved. IC adenosine boluses were administered at a dose of 15 to 20 microgram in the right and 18 to 24 microgram in the left coronary artery. FFR was calculated as the ratio of the distal coronary pressure (from pressure guide wire) to the aortic pressure (guide catheter) at maximal hyperemia. RESULTS: A total of 26 left anterior descending, 23 right, 9 left circumflex, and 3 left main coronary arteries were evaluated. Mean percent stenosis for both groups was 55.8% +/- 23.6% (range 0% to 95%), and mean FFR was 0.78 +/- 0.15 (range 0.41 to 0.98). There was a strong and linear correlation between FFR measurements with IV and IC adenosine (R = 0.978, y = 0. 032 + 0.964x, P <.001). The agreement between the 2 sets of measurements was also high, with a mean difference in FFR of -0.004 +/- 0.03. However, a small random scatter in both directions of FFR measurements was noted with 5 lesions (8.3%) where FFR with IC adenosine was higher by 0.05 or more compared with IV infusions, suggesting a suboptimal hyperemic response in these patients. Changes in heart rate and blood pressure were significantly higher with IV adenosine. Two patients with IV, but none with IC adenosine, had severe side effects (bronchospasm and severe nausea). CONCLUSION: These results suggest that IC adenosine is equivalent to IV infusion for the determination of FFR in the majority of patients. However, in a small percentage of cases, coronary hyperemia was suboptimal with IC adenosine.

Adenosine↗
PubMed2000

Mammalian sperm-egg fusion: evidence that epididymal protein DE plays a role in mouse gamete fusion.

Rat epididymal protein DE associates with the sperm surface during epididymal maturation and is a candidate molecule for mediating gamete membrane fusion in the rat. Here, we provide evidence supporting a role for DE in mouse sperm-egg fusion. Western blot studies indicated that the antibody against rat protein DE can recognize the mouse homologue in both epididymal tissue and sperm extracts. Indirect immunofluorescence studies using this antibody localized the protein on the dorsal region of the acrosome. Experiments in which zona-free mouse eggs were coincubated with mouse capacitated sperm in the presence of DE showed a significant and concentration-dependent inhibition in the percentage of penetrated eggs, with no effect on either the percentage of oocytes with bound sperm or the number of sperm bound per egg. Immunofluorescence experiments revealed specific DE-binding sites on the fusogenic region of mouse eggs. Because mouse sperm can penetrate zona-free rat eggs, the participation of DE in this interaction was also investigated. The presence of the protein during gamete coincubation produced a significant reduction in the percentage of penetrated eggs, without affecting the binding of sperm to the oolemma. These observations support the involvement of DE in an event subsequent to sperm-egg binding and leading to fusion in both homologous (mouse-mouse) and heterologous (mouse-rat) sperm-egg interaction. The lack of disintegrin domains in DE indicates that the protein interacts with its egg-binding sites through a novel mechanism that does not involve the reported disintegrin-integrin interaction.

Animals↗
PubMed2000

The mother-child dyad facing trauma: a developmental outlook.

The effects of trauma in children are amply documented. This paper investigated the relationship between children's age and posttraumatic clusters of symptoms 30 months after the end of the Gulf War and the mother's reaction to the trauma 6 and 30 months after the war. Fifty-one children aged 6 to 8 years (3 to 5 years during the war) and their mothers were interviewed. Results showed no age differences in the various posttraumatic symptoms of the children. Correlations between the children's posttraumatic symptoms and both the general and the specific posttraumatic symptoms of their mothers were positive and significant in the 6-year-olds, positive and nonsignificant in the 7-year-olds, and nonsignificant and mostly negative in the 8-year-olds. These findings may reflect the developmental changes that render the older child more autonomous and the younger child rigidly attached to the mother after a traumatic event.

Adult↗
PubMed2000

MAG3-F0 scintigraphy in decision making for emergency intervention in renal colic after helical CT positive for a urolith.

UNLABELLED: Patients with renal colic are evaluated with clinical, laboratory, and imaging methods for stratification for emergency decompression, medical treatment, or discharge and follow up. The current standard practice is heavily based on unenhanced helical CT for detecting uroliths. However, the presence of a urolith does not necessarily mean that the kidney is obstructed and requires emergency decompression. In this study, technetium-mercaptoacetyltriglycine (MAG3) diuretic scintirenography was used to detect obstruction in patients with renal colic. The contribution of this test to patient management after positive findings from helical CT was also studied. METHODS: Diagnostic criteria were established on the basis of previous experience with 60 patients who had renal colic and had undergone radiography of the kidneys, ureters, and urinary bladder (KUB) and diuretic Tc-MAG3 scintirenography and were followed up to correlate scintigraphic findings with clinical outcome. Subsequently, 80 patients with renal colic underwent scintigraphy within 12 h of presentation in the emergency room, after abdominal helical CT showed findings positive for calculus and suggestive of obstruction. After therapeutic oral or intravenous hydration and analgesics, diuretic dynamic renal scintigraphy (flow, function, delayed imaging) was performed after intravenous injections of 10 mCi (370 MBq) 99mTc-MAG3 and 40 mg furosemide (at zero time, or F0). Results were available soon after completion of the study and were considered in patient management. Four characteristic patterns of scintirenography, essential in patient stratification and treatment, had been standardized and were used for interpretation of the studies: the unobstructed kidney; the partially obstructed kidney, proximally or distally obstructed, with mild to severe obstruction and impairment of function; the totally obstructed kidney, with arrested renal function; and the unobstructed but dysfunctioning kidney after decompression, or stunned kidney. RESULTS: Among the 80 patients with positive helical CT findings, 56.5% were found to have obstruction by scintigraphy (32.5% partially, 24% completely); the remaining 43.5% did not have obstruction (21% without an indication of recent obstruction and 22.5% with stunned kidneys after spontaneous decompression). Occasionally, findings of preexistent urine extravasation or infection were present. Patients who, by scintigraphy, never had obstruction or had experienced spontaneous decompression did not require admission or emergency intervention; those with complete or severe obstruction required admission and decompression for relief of pain or restoration of function, whereas those with mild obstruction were treated variably with forced fluids, analgesics, or, less frequently, elective surgery. Outcome information from clinical examination, imaging, and interventional findings indicated that this stratification was successful. The test caused no side effects. CONCLUSION: For renal colic, clinical selection, KUB radiography, and even positive helical CT findings were all found to have a low positive predictive value for obstruction (in this study, 35%, 32%, and 56% respectively). Anatomic studies, including helical CT, should be followed by diuretic MAG3-F0 scintirenography to diagnose and quantify or exclude obstruction, detect spontaneous decompression, and appropriately stratify patients for emergency intervention, observation and medical therapy, or further work-up and discharge with referral to the clinic.

Adult↗
PubMed2000

Membranous glomerulopathy with Bowman's capsular and tubular basement membrane deposits.

Bowman's capsular and tubular basement membrane (TBM) deposits are an extremely unusual finding in non-lupus membranous glomerulopathy (MGN). We report three atypical cases of MGN with abundant Bowman's capsular and TBM deposits. In two cases, MGN was idiopathic; in the third case, MGN occurred in the renal allograft in the setting of HCV seropositivity. In addition to the usual glomerular capillary wall deposits, immunofluorescence and electron microscopy revealed extensive immune deposits within Bowman's capsule and TBMs, predominantly at the base of parietal and tubular epithelial cells. These cases suggest a potential pathomechanism of autoantibody to secreted epithelial antigens shared by visceral, parietal, and tubular epithelial cells. In all three cases, indirect immunofluorescence was unable to detect autoantibody to normal renal epithelial or matrix constituents. Furthermore, ELISA was unable to demonstrate circulating antibody to major extracellular matrix components. The implications of these findings for the pathogenesis of MGN are explored.

Adult↗
PubMed1999

The Tourette syndrome diagnostic confidence index: development and clinical associations.

BACKGROUND: The clinical characteristics of Tourette syndrome (TS) present challenges for the systematic determination of whether individuals are affected and severity. Vocal and motor tics wax and wane, decrease over time, and may be voluntarily suppressible, and therefore may be absent at interview. Current instruments measure symptoms at interview or rate symptom severity only. METHOD: To minimize error in case ascertainment and produce an instrument measuring lifetime likelihood of having had TS, clinical members of the American Tourette Syndrome Association International Genetic Collaboration developed the Diagnostic Confidence Index (DCI). The expert group worked collaboratively with progressive revision in consensus workshops using existing diagnostic criteria as guidelines. The DCI produces a score from 0 to 100 that is a measure of the likelihood of having or ever having had TS. RESULTS: The DCI was administered to 280 consecutive patients with TS attending a TS clinic; 264 (94%) completed it, indicating high feasibility and acceptability. Its correlation with other instruments and associations with psychopathology provide support for its being a lifetime measure of TS. CONCLUSIONS: The DCI is a useful, practicable instrument in the clinic or research practice allowing an assessment of lifetime likelihood of TS. Further work is needed to test the DCI's psychometric properties, such as its validity and reliability in populations of interest.

Adolescent↗
PubMed1999

In vivo assessment of stent expansion and recoil in normal porcine coronary arteries: differential outcome by stent design.

BACKGROUND: Despite the routine use of high pressure, coronary stents generally fail to achieve a cross-sectional area (CSA) >60% to 80% of the nominal CSA of their dilating balloon. The extent to which incomplete balloon expansion and postdeflation stent recoil contribute to this failure has not been fully evaluated. METHODS AND RESULTS: Thirty-two stents (8 Gianturco-Roubin II, 8 Palmaz-Schatz, 8 MultiLink, and 8 NIR) were deployed in nondiseased coronary arteries of 8 Yorkshire pigs. All stents were then expanded according to 1 of 3 balloon strategies: appropriately sized compliant balloons, oversized compliant balloons, or oversized noncompliant balloons. Continuous ultrasound imaging was performed during stepwise balloon inflation and deflation, with an 0.018-in imaging core positioned within the guidewire lumen of the balloon. In these normal arteries, balloon underexpansion relative to the nominal size was not observed. After balloon deflation, however, all stents showed significant recoil from their maximum inflated CSA. Recoil was significantly greater for the coil Gianturco-Roubin II stent (30% CSA) than for the 3 slotted-tube stent designs (15% to 17% CSA). CONCLUSIONS: In normal, compliant coronary arteries, stent recoil is the predominant mechanism by which stents fail to achieve the nominal CSA of their dilating balloon. The magnitude of this in vivo stent recoil is significantly greater than reported from bench testing and varies with stent design (coil versus slotted tube). Postdilatation strategies that result in controlled stent overexpansion are needed to overcome this recoil phenomenon and result in a final stent CSA that approximates the reference artery CSA.

Angioplasty, Balloon, Coronary↗
PubMed1999

Economics, health-related quality of life, and cost-effectiveness methods for the TACTICS (Treat Angina With Aggrastat [tirofiban]] and Determine Cost of Therapy with Invasive or Conservative Strategy)-TIMI 18 trial.

Concern over escalating health care costs has led to increasing focus on economics and assessment of outcome measures for expensive forms of therapy. This is being investigated in the Treat Angina With Aggrastat [tirofiban] and Determine Cost of Therapy with Invasive or Conservative Strategy (TACTICS)-TIMI 18 trial, a randomized trial comparing outcome of patients with unstable angina or non-Q-wave myocardial infarction treated with tirofiban and then randomized to an invasive versus a conservative strategy. Hospital and professional costs initially and over 6 months, including outpatient costs, will be assessed. Hospital costs will be determined for patients in the United States from the UB92 formulation of the hospital bill, with costs derived from charges using departmental cost to charge ratios. Professional costs will be determined by accounting for professional services and then converted to resource units using the Resource Based Relative Value Scale and then to costs using the Medicare conversion factor. Follow-up resource consumption, including medications, testing and office visits, will be carefully measured with a Patient Economic Form, and converted to costs from the Medicare fee schedule. Health-related quality of life will be assessed with a specific instrument, the Seattle Angina Questionnaire, and a general instrument, the Health Utilities Index at baseline, 1, and 6 months. The Health Utilities Index will also be used to construct a utility. By knowing utility and survival, quality-adjusted life years will be determined. These measures will permit the performance of a cost-effectiveness analysis, with the cost-effectiveness of the invasive strategy defined and the difference in cost between the invasive and conservative strategies divided by the difference in quality-adjusted life years. The economic and health-related quality of life aspects of TACTICS-TIMI 18 are an integral part of the study design and will provide a comprehensive understanding of the impact of invasive versus conservative management strategies on a broad range of outcomes after hospitalization for unstable angina or non-Q-wave myocardial infarction.

Angina Pectoris↗
PubMed1999

Effect of transradial access on quality of life and cost of cardiac catheterization: A randomized comparison.

BACKGROUND: Transradial access is a recently developed alternative for diagnostic cardiac catheterization. Its effects on quality of life after the procedure, patient preference, and cost are unknown. METHODS AND RESULTS: We performed a randomized single-center trial in which 99 patients underwent transfemoral and 101 underwent transradial diagnostic cardiac catheterization. Quality of life was measured with the SF-36 and visual analog scales at baseline, 1 day, and 1 week. Patients were examined at 1 day and at 1 week after for complications. Costs were measured prospectively. One patient in the femoral group and 2 in the radial group crossed over to the alternative access site. There were no major access site complications. One patient in the transfemoral group had a minor stroke. Transradial catheterization significantly reduced median length of stay (3.6 vs 10.4 hours, P <.0001). Over the first day after the procedure, measures of bodily pain, back pain, and walking ability favored the transradial group (P <.05 for all comparisons). Over the week after the procedure, changes in role limitations caused by physical health, bodily pain, and back pain favored the transradial group (P <.05 for all comparisons). There was a strong patient preference for transradial catheterization as well (P <. 0001). Transradial catheterization led to significant reductions in bed, pharmacy, and total hospital costs ($2010 vs $2299, P <.0001). CONCLUSIONS: Among patients undergoing diagnostic cardiac catheterization, transradial access leads to improved quality of life after the procedure, is strongly preferred by patients, and reduces hospital costs.

Cardiac Catheterization↗
PubMed1999

Economic impact of GPIIB/IIIA blockade after high-risk angioplasty: results from the RESTORE trial. Randomized Efficacy Study of Tirofiban for Outcomes and Restenosis.

OBJECTIVE: This study was conducted to assess the impact of GPIIb/IIIa blockade with tirofiban on costs during the initial hospitalization and at 30 days among patients undergoing high-risk coronary angioplasty. BACKGROUND: GPIIb/IIIa blockers are a new class of compounds that have been shown in clinical studies to prevent complications after high-risk angioplasty. METHODS: The RESTORE trial was a multinational, blinded placebo-controlled study of 2,197 patients randomized to tirofiban or placebo following coronary angioplasty. This economic assessment was a prospective substudy of the RESTORE trial, and included 1,920 patients enrolled in the U.S. Costs were estimated for the U.S. cohort based on their utilization of healthcare resources and on costs measured directly in 820 U.S. patients at 30 sites. RESULTS: There was a 36% difference in the rate of the composite event of death, myocardial infarction (MI) and revascularization at two days between tirofiban and placebo (8% vs. 12%, p = 0.002). This difference was attributed to a reduction in nonfatal MI, repeat angioplasty, coronary surgery and stent placement. These clinical benefits followed a similar trend at 30 days, with a 16% reduction in the composite event (p = 0.10). In-hospital cost, including professional and study drug costs, was $12,145 +/- 5,882 with placebo versus $12,230 +/- 5,527 with tirofiban (p = 0.75). The 30-day cost was $12,402 +/- 6,147 with placebo versus $12,446 +/- 5,814 with tirofiban (p = 0.87). CONCLUSIONS: Tirofiban has been shown to decrease in-hospital and possibly 30-day events after high-risk angioplasty. The beneficial clinical effects of tirofiban in high-risk patients can be achieved at no increased cost.

Adult↗
PubMed1999

A normed study of face recognition in autism and related disorders.

Although the interpretation of studies of face recognition in older children, adolescents, and adults with autism is complicated by the fact that participating samples and adopted methodologies vary significantly, there is nevertheless strong evidence indicating processing peculiarities even when task performance is not deficient. Much less is known about face recognition abilities in younger children with autism. This study employed a well-normed task of face recognition to measure this ability in 102 young children with autism, pervasive developmental disorder not otherwise specified (PDDNOS), and non-PDD disorders (mental retardation and language disorders) matched on chronological age and nonverbal mental age, and in a subsample of 51 children divided equally in the same three groups matched on chronological age and verbal mental age. There were pronounced deficits of face recognition in the autistic group relative to the other nonverbally matched and verbally matched groups. Performance on two comparison tasks did not reveal significant differences when verbal ability was adequately controlled. We concluded that young children with autism have face recognition deficits that cannot be attributed to overall cognitive abilities or task demands. In contrast to controls, there was a lower correlation between performance on face recognition and nonverbal intelligence, suggesting that in autism face recognition is less correlated with general cognitive capacity. Contrary to our expectation, children with PDDNOS did not show face recognition deficits.

Adult↗
PubMed1999

Elements or objects? Testing the movement filter hypothesis.

P. McLeod, J. Driver, and J. Crisp (1988) proposed the existence of a movement filter in the human early visual system. This filter preattentively segregates all moving stimuli in the visual field from all stationery stimuli (McLeod et al., 1988) and all stimuli moving in one direction from those moving in another (P. McLeod, J. Driver, Z. Dienes, & J. Crisp, 1991). The primary experimental paradigm that provides evidence for the movement filter is the visual search task. McLeod et al. (1988) demonstrated that a target defined by motion and shape perceptually pops out of a conjunctive display. Four experiments are presented that demonstrate that the output of the movement filter may depend on global characteristics of the display. When a moving element perceptually groups with a static object, preattentive segregation does not occur. However, when the same element does not perceptually group with a static object, preattentive segregation occurs.

Analysis of Variance↗