Biomedical subjects

John D Hughes

Publications and source records attributed to John D Hughes.

11 recordsLinked to original sources

PubMed2007

Network model of decreased context utilization in autism spectrum disorder.

Individuals with autism spectrum disorders (ASD) demonstrate impaired utilization of context, which allows for superior performance on the "false memory" task. We report the application of a simplified parallel distributed processing model of context utilization to the false memory task. For individuals without ASD, experiments support a model wherein presentation of one word, e.g., ''apple,'' strongly activates the neighboring nodes of closely related words such as ''fruit,'' ''tree,'' whereas in ASD these neighboring nodes are relatively less activated. We demonstrate this model to be consistent with the superior performance on recognition testing on the false memory test, but not on free recall. This may have an anatomic basis in diminished hippocampal neuronal arborization and the abnormal minicolumnar pathology in ASD.

Association Learning↗

PubMed2006

A systems approach to behavioral neurobiology: integrating psychodynamics and neuroscience in a psychiatric curriculum.

In the practice of medicine, an understanding of the biological functioning of organs and organ systems is the basis for theories of pathology and clinical practice. If psychoanalysis is to be accepted by the medical and psychiatric community, it must be based on a sophisticated understanding of the organ from which mental and emotional experiences emanate and use scientifically acceptable language. Each approach to psychotherapy has its own vocabulary for describing neuropsychological processes. Neurobiological vocabulary provides the various factions "neutral ground" upon which to carry on a multidisciplinary integrative dialogue. An understanding of behavioral neuroscience allows the therapist to look beyond the labels that spawn division and identify unifying biological principles that are described in a variety of ways in a multitude of theories. We contend that the neural network/representational approach to neurobiology views human mental experience as the result of multiple complex integrated systems, and is therefore holistic and antireductionistic in its perspective. Such a biologically informed psychotherapy facilitates integration of skill sets and flexibility in technique. With these principles in mind, the therapist can base his or her approach to the patient based on these principles rather than on devotion to one particular "school" or another. Because behavioral neuroscience supports many of the basic tenets of psychoanalytic theory, such an integrative psychotherapy would be psychodynamically informed. In this paper, we outline some of the ideas we present in our neuroscience course and how we relate biological concepts with some core principles of psychodynamics and psychotherapy.

Behavior Therapy↗

PubMed2005

The limitations of magnetic resonance angiography in the diagnosis of renal artery stenosis: comparative analysis with conventional arteriography.

PURPOSE: Gadolinium-enhanced magnetic resonance angiography (MRA) is commonly used as a screening modality for the detection of renal artery stenosis. However, evidence supporting its utility in clinical practice is lacking; few rigorous studies have compared MRA with contrast arteriography (CA). After making anecdotal clinical observations that MRA sometimes overestimated the degree of renal artery stenosis, we decided to determine the interobserver variability, sensitivity, specificity, and diagnostic accuracy of MRA compared with CA. METHODS: From September 1999 to April 2003, we evaluated 68 renal arteries in 34 patients with clinically suspected renal artery stenosis using both MRA and CA. All studies were independently reviewed by four blinded observers. Renal arteries were categorized by MRA as normal, <50%, and >50% stenosis/occlusion. The sensitivity, specificity, and accuracy of MRA detection of renal artery stenosis were compared to CA as the gold standard. Interobserver variability (kappa) was also calculated. RESULTS: MRA demonstrated 87% sensitivity, 69% specificity, 85% accuracy, 95% negative predictive value, and 51% positive predictive value for the diagnosis of renal artery stenosis. Interobserver agreement was moderate for MRA (kappa = 0.53) and good for CA (kappa = 0.76). In 21 arteries (31%), MRA was falsely positive. CONCLUSIONS: In patients with a high clinical suspicion of renal artery stenosis, MRA is 87% sensitive in the detection of >50% stenosis. However, MRA is relatively nonspecific compared with CA and results in significant overestimation of renal artery stenosis in nearly one third of patients. To reduce unnecessary CA, clinicians should consider supplemental studies.

Adult↗

PubMed2004

Hyponatremic hypertensive syndrome (HHS) in an 18-month old-child presenting as malignant hypertension: a case report.

BACKGROUND: The combination of hyponatremia and renovascular hypertension is called hyponatremic hypertensive syndrome (HHS). Malignant hypertension as a presentation has been reported in adults with HHS but is rare in children. CASE PRESENTATION: An eighteen month-old male presented with drowsiness, sudden onset status epilepticus and blood pressure of 210/160. The electrolytes on admission revealed sodium of 120 mEq/L and potassium of 2.1 mEq/L. The peripheral renin activity (PRA) was 172 ng/ml/min (normal 3-11 ng/ml/min) and serum aldosterone level was 91 ng/dl (normal 4 to 16 ng/dl). Patient underwent angioplasty with no success, followed by surgical correction. Two years since the diagnosis, the blood pressure is controlled with labetolol and amlodipine (at less than sixth of the pre-operative dosages). The PRA is 2.4 ng/ml/min and aldosterone 15.5 ng/dl. The child not only had three renal arteries on left but all of them were stenosed which to best of our knowledge has not been described. CONCLUSION: As uncommon as HHS with malignant hypertension may be in adults it is under-reported in children and purpose of the case report is to raise its awareness.

Aldosterone↗

PubMed2004

A new look at outcomes after infrainguinal bypass surgery: traditional reporting standards systematically underestimate the expenditure of effort required to attain limb salvage.

BACKGROUND: Graft patency, limb salvage, and mortality are the traditional means of assessing the outcome of infrainguinal bypass surgery (IBS). However, these measures underestimate patient morbidity and fail to consider the entire spectrum of treatment required to restore the patients to their premorbid state. The aim of this study was to quantify the efforts required to achieve limb salvage by assessing three nontraditional outcomes: (1). index limb reoperation rate in 3 months, (2). hospital readmission rate in the first 6 months after IBS, and (3). wound-healing time. METHODS: We retrospectively analyzed 318 IBSs performed at a single institution. Repeat operations for limb or graft-related problems and readmissions within 6 months of the initial operation were recorded. When available, wound-healing time was determined. Pertinent demographics and comorbidities were subjected to univariate and multivariate analysis to determine risk factors for adverse outcomes. RESULTS: Seventy-two percent of patients underwent IBS for critical limb ischemia (CLI), and 84% had below-knee popliteal or distal bypasses. Among those who underwent IBS for CLI, 48.9% of patients required at least one reoperation within 3 months. Within 6 months, 49.3% of patients required hospital readmission. Time to heal exceeded 3 months in 54% of patients. After multivariate analysis, tissue loss and minority status were significant risk factors for reoperation within 3 months. Tissue loss and renal failure increased the odds for readmission within 6 months. Diabetes was the sole risk factor for prolonged wound healing. CONCLUSIONS: IBS for limb salvage is often complicated by prolonged recovery and multiple reoperations and readmissions. Traditional reporting standards for limb salvage operations need modification to reflect the true outcome of such procedures.

Aged↗

PubMed2004

Effect of anxiolytics on cognitive flexibility in problem solving.

OBJECTIVE: Our purpose is to examine the effect of different classes of anxiolytics on cognitive flexibility. BACKGROUND: Situational stressors and anxiety impede performance on "creativity" tests requiring cognitive flexibility. Noradrenergic agents have been shown to modulate cognitive flexibility as assessed by performance on anagrams. To determine whether these findings on noradrenergic modulation of cognitive flexibility are specific to the noradrenergic system or are a nonspecific anxiety effect, we compared the effects of propranolol, lorazepam, and placebo on the anagram task. METHODS: Subjects attended 3 test sessions. Prior to each session, subjects were given 1 of the 3 drugs. As in previous research, the natural log of the solution latency of each test item was summed for each test session and compared across drug conditions. RESULTS: For subjects able to solve the anagrams, solution times after propranolol, but not lorazepam, were significantly lower than after placebo. CONCLUSIONS: Therefore, this suggests that the phenomenon of noradrenergic modulation of cognitive flexibility does not result from a nonspecific anxiolytic effect, but rather is specific to the noradrenergic system.

Administration, Oral↗

PubMed2003

What you get out of memory depends on the question you ask.

Following study, participants received 2 tests. The 1st was a recognition test; the 2nd was designed to tap recollection. The objective was to examine performance on Test 1 conditional on Test 2 performance. In Experiment 1, contrary to process dissociation assumptions, exclusion errors better predicted subsequent recollection than did inclusion errors. In Experiments 2 and 3, with alternate questions posed on Test 2, words having high estimates of recollection with one question had high estimates of familiarity with the other question. Results supported the following: (a) the 2-test procedure has considerable potential for elucidating the relationship between recollection and familiarity; (b) there is substantial evidence for dependency between such processes when estimates are obtained using the process dissociation and remember-know procedures; and (c) order of information access appears to depend on the question posed to the memory system.

Attention↗

PubMed2003

Is early postoperative duplex scan surveillance of leg bypass grafts clinically important?

PURPOSE: The typical leg bypass surveillance program begins with a duplex scan evaluation of the vein graft 3 months after surgery; studies are repeated every 3 months during the first year of follow-up and are fully reimbursed by our Medicare carrier. Some authors have recommended early (before discharge or first postoperative visit) duplex scanning to identify high-risk grafts. However, the natural history of velocity disturbances detected with early scans is unclear, and furthermore, such studies are not reimbursed by Medicare. METHODS: We reviewed all infrainguinal vein bypass grafts prospectively entered into a surveillance protocol that included an early (<6 weeks) duplex scan study. Routine completion angiography was performed at the initial operation in all patients. Early duplex scan results, the need for graft revision, and detailed follow-up of these bypass grafts were analyzed. RESULTS: Early duplex scans were performed in 224 bypass grafts placed in 204 patients. Early scans were abnormal (peak systolic velocity [PSV], >200 cm/s) in 58 grafts (26%). Six grafts of the 58 (10.3%; 2.7%) with an early abnormal duplex scan and unrepaired defects occluded during the follow-up period. Thirty grafts were revised on the basis of the initial early scan; 23 of these revisions were performed for critical or rapidly progressive lesions in the first 3 postoperative months. Seven lesions progressed more slowly and were repaired at a mean of 8 months after surgery. Interestingly, 22 flow abnormalities (37%) resolved or stabilized despite a PSV of more than 300 cm/s in six cases (27%). Clear duplex scan evidence of regression or progression of these early flow abnormalities occurred within 3 months in 51/58 cases (88%). A total of 68 grafts (30%) were revised during the entire study period; 30 of these (44%) were on the basis of the early abnormal scan. CONCLUSION: Despite normal completion arteriography, early graft velocity abnormalities are strikingly common and were detected in 26% of the 224 infrainguinal vein grafts in this series. These lesions were clinically important because 52% necessitated revision. Surprisingly, however, 38% of these early flow disturbances resolved, despite a PSV of more than 300 cm/s in 27% of cases. Early duplex scan surveillance singularly detects a clinically significant subgroup of grafts that need revision. The possible origin of these early lesions deserves further inquiry, but on the basis of its clinical yield, we recommend that early duplex scan surveillance of infrainguinal bypass grafts should be routine and should be considered for Medicare reimbursement.

Adult↗

PubMed2002

Central beta-adrenergic modulation of cognitive flexibility.

Situational stressors and anxiety impede performance on creativity tests requiring cognitive flexibility. Preliminary research revealed better performance on a task requiring cognitive flexibility, the anagram task, after propranolol (beta-adrenergic antagonist) than after ephedrine (beta-adrenergic agonist). However, propranolol and ephedrine have both peripheral and central beta-adrenergic effects. In order to determine whether noradrenergic modulation of cognitive flexibility is a centrally or peripherally mediated phenomenon, we compared the effects of propranolol (peripheral and central beta-blocker), nadolol (peripheral beta-blocker), and placebo on anagram task performance. Solution latency scores for each subject were compared across the drug conditions. Anagram solution latency scores after propranolol were significantly lower than after nadolol. This suggests a centrally mediated modulatory influence of the noradrenergic system on cognitive flexibility.

Adrenergic beta-Agonists↗

PubMed2002

Distal revascularization-interval ligation: a durable and effective treatment for ischemic steal syndrome after hemodialysis access.

PURPOSE: The treatment of hemodialysis access-induced ischemic steal syndrome is challenging. Despite promising early results with the distal revascularization-interval ligation (DRIL) procedure, the operation has not been widely adopted because of concerns about its complexity and long-term efficacy. The purpose of this report was to determine the efficacy and durability of the DRIL procedure in relieving hand ischemia and in maintaining access patency in the setting of hemodialysis access-induced ischemia. METHODS: A retrospective review was performed of all patients who underwent the DRIL procedure for access-induced ischemia. Demographic information was compiled, as were data regarding access and bypass patency, limb salvage, and patient survival. Arteriovenous access and brachial artery bypass patency rates were determined with life-table methods. RESULTS: Between 1995 and 2001, we performed 55 DRIL procedures in 52 patients (35 women and 17 men; mean age, 60.8 years; range, 30 to 86 years). The indications for surgery were ischemic pain in 27 patients, tissue loss in 20 patients, loss of neurologic function in four patients, and pain on hemodialysis in one patient. Most patients (92%) had diabetes. The mean interval from access placement to DRIL was 7.4 months (range, 1 to 84 months). The mean follow-up interval was 16 months (range, 1 to 67 months). The brachial artery bypass primary patency rate was 80% at 4 years, and the arteriovenous access primary patency rate was 83% at 1 year. Forty-seven of 52 patients (90%) had substantial or complete relief of ischemic hand symptoms, and 15 of 20 patients with digital ischemic lesions have healed completely. CONCLUSION: DRIL is a durable and effective procedure that reliably accomplishes the twin goals in the treatment of angioaccess-induced ischemia: persistent relief of hand ischemia and continued access patency.

Adult↗

PubMedDate not supplied

A neural systems-based neurobiology and neuropsychiatry course: integrating biology, psychodynamics, and psychology in the psychiatric curriculum.

OBJECTIVE: Psychotherapy and biological psychiatry remain divided in psychiatry residency curricula. Behavioral neurobiology and neuropsychiatry provide a systems-level framework that allows teachers to integrate biology, psychodynamics, and psychology. METHOD: The authors detail the underlying assumptions and outline of a neural systems-based neuroscience course they teach at the National Capital Consortium Psychiatry Residency Program. They review course assessment reports and classroom observations. RESULTS: Self-report measures and teacher observations are encouraging. By the end of the course, residents are able to discuss both neurobiological and psychodynamic/psychological concepts of distributed biological neural networks. They verbalize an understanding that psychology is biology, that any distinction is artificial, and that both are valuable. CONCLUSIONS: A neuroscience curriculum founded on the underlying principles of behavioral neurobiology and neuropsychiatry is inherently anti-reductionistic and facilitates the acquisition of detailed information as well as critical thinking and cross-disciplinary correlations with psychological theories and psychotherapy.

Brain↗