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Biomedical subjects

K L Weiss

Publications and source records attributed to K L Weiss.

At least 19 recordsLinked to original sources
PubMed2001

An unhydrolyzable analogue of N-(4-hydroxyphenyl)retinamide. synthesis and preliminary biological studies.

The synthesis of a nonhydrolyzable, carbon-linked analogue (4-HBR) of the retinoid N-(4-hydroxyphenyl)retinamide (4-HPR) using Umpolung methods is described. Preliminary studies of biological activity show 4-HBR is similar to 4-HPR in its actions although a potentially relevant and desirable difference is its reduced suppression of plasma vitamin A levels. These results show that 4-HPR does not have to be hydrolyzed to retinoic acid to produce its chemotherapeutic effects.

Animals↗
PubMed2001

Cranial nerve clock. Part 1. A declarative memory paradigm.

RATIONALE AND OBJECTIVES: The authors performed this study to compare a declarative memory paradigm developed to help teach medical students about the cranial nerves with a traditional text-based approach. MATERIALS AND METHODS: The authors designed a clock-based paradigm to help medical students learn about the cranial nerves. To enhance memorization and related brain activation, the paradigm uses visual, spatial, and word associations in the context of an analog clock face. Twenty-one undergraduate students were randomly divided into two groups. Group T viewed traditional text slides, and group C viewed text slides followed by the corresponding cranial clock slides. Subjects were tested before and after these sessions. RESULTS: Group C performed significantly better than group T in learning the names of the cranial nerves and their correct order (P < .011). Recall of name, number, and function was better for 11 of 12 cranial nerves, with statistical significance reached for nerves III (P = .005), V (P = .04), and X (P = .03). CONCLUSION: Alternative teaching strategies may help improve declarative memory.

Cranial Nerves↗
PubMed2001

Cranial nerve clock. Part II: functional MR imaging of brain activation during a declarative memory task.

RATIONALE AND OBJECTIVES: The authors performed this study to assess brain activation during encoding and successful recall with a declarative memory paradigm that has previously been demonstrated to be effective for teaching students about the cranial nerves. MATERIALS AND METHODS: Twenty-four students underwent functional magnetic resonance (MR) imaging during encoding and recall of the name, number, and function of the 12 cranial nerves. The students viewed mnemonic graphic and text slides related to individual nerves, as well as their respective control slides. For the recall paradigm, students were prompted with the numbers 1-12 (test condition) intermixed with the number 14 (control condition). Subjects were tested about their knowledge of cranial nerves outside the MR unit before and after functional MR imaging. RESULTS: Students learned about the cranial nerves while undergoing functional MR imaging (mean post- vs preparadigm score, 8.1 +/- 3.4 [of a possible 12] vs 0.75 +/- 0.94, bilateral prefrontal cortex, left greater than right; P < 2.0 x 10(-12)) and maintained this knowledge at I week. The encoding and recall paradigms elicited distributed networks of brain activation. Encoding revealed statistically significant activation in the bilateral prefrontal cortex, left greater than right [corrected]; bilateral occipital and parietal associative cortices, parahippocampus region, fusiform gyri, and cerebellum. Successful recall activated the left much more than the right prefrontal, parietal associative, and anterior cingulate cortices; bilateral precuneus and cerebellum; and right more than the left posterior cingulate. CONCLUSION: A predictable pattern of brain activation at functional MR imaging accompanies the encoding and successful recall of the cranial nerves with this declarative memory paradigm.

Adult↗
PubMed2001

Serotonin mediated cluster headache, trigeminal neuralgia, glossopharyngeal neuralgia, and superior laryngeal neuralgia with SAD chronicity.

Cluster headache is a rare and severe pain syndrome with elusive pathophysiology. Serotonin pathways within the brainstem may be implicated in cluster headache with seasonal affective disorder and a subset of cranial nerve neuralgias. We describe and chronicle a syndrome consisting of cluster headache, seasonal affective disorder, with associated trigeminal, glossopharyngeal, superior laryngeal neuralgias in an 11-year-old female. Pharmacologic interventions for this patient were examined in conjunction with current classification, location and function of serotonin receptors. Etiology is postulated as mixed cranial nerve excitation via endogenous 5-HT (agonist) activity of 5-HT3 receptors within the nucleus tractus solitarius and trigeminal tract nucleus.

Cluster Headache↗
PubMed2000

Proton magnetic resonance spectroscopic observations of epilepsia partialis continua in children.

We performed magnetic resonance spectroscopy in three pediatric patients (two boys and one girl, ages 11 to 17 years) with epilepsia partialis continua. Single-voxel proton magnetic resonance spectroscopy was performed on each patient. Data were acquired from voxels of 4 or 8 cm3 from the affected hemisphere and from contralateral homologous regions. The spectral peaks of several metabolites (N-acetyl-aspartate, choline, creatine, and lactate) were measured. Neuropathologic findings revealed Rasmussen's syndrome in two children and gliosis in one. We observed increased lactate-to-creatine ratios and reduced N-acetyl-aspartate-to-creatine ratios in the affected hemispheres in all three children with epilepsia partialis continua. These data support previous reports. The largest increase in the lactate-to-creatine ratio was detected in a patient with Rasmussen's syndrome and ongoing epilepsia partialis continua at the time of measurement. The other two patients had an increase in the lactate-to-creatine ratio and a decrease in the N-acetyl-aspartate-to-creatine ratio in the affected area. The increased lactate-to-creatine ratio was associated with recurrent focal seizures from different underlying pathologies.

Adolescent↗
PubMed1998

Functional MR imaging in patients with epilepsy.

Recent advances in MR imaging have significantly enhanced the diagnosis and management of epilepsy. This article focuses on the expanding role of functional MR imaging in our imaging armamentarium. Diffusion, perfusion, and BOLD functional MR imaging techniques are discussed in detail with emphasis on epilepsy applications. Functional MR imaging seizure focus localization, eloquent cortex mapping, and the potential for functional MR imaging to replace Wada testing are explored. With anticipated future developments, functional MR imaging holds great promise for epilepsy patients.

Brain↗
PubMed1997

Ethnographic detection and description of family strategies for child care: applications to the study of cerebral palsy.

Presented a framework for describing and classifying patterns, or strategies, used by families who have children with moderate to severe cerebral palsy, in caring for their child. Forty families were administered a structured interview regarding details of their day-to-day experience in caring for their child. Four reliably distinct patterns were identified. The patterns were compared with respect to other characteristics of the family. Results suggest at least three patterns that appear to be relatively adaptive, and one that appears relatively less so. Results are discussed in terms of the definition of successful family adaptation, the heterogeneity of adaptive family patterns in this population, and some clinical implications.

Adaptation, Psychological↗
PubMed1994

MRI monitoring of vigabatrin-induced intramyelinic edema in dogs.

Chronic administration of vigabatrin (gamma-vinyl GABA) in dogs produces reversible microvacuolation (intramyelinic edema) in discrete brain regions. Histologic changes are most notable in the columns of the fornix and regions of the hypothalamus, thalamus, optic tract, and hippocampus. In an attempt to image these changes in vivo, we performed high-field MRI on seven treated and four control dogs at baseline and after 15 weeks of dosing with vigabatrin (300 mg/kg/d). All dogs underwent parallel electrophysiologic assessment to determine the effects of vigabatrin on afferent conduction. At 15 weeks, all treated dogs showed increased T2- and decreased T1-weighted signals, with changes from baseline most prominent in the columns of the fornix and to a lesser degree in the surrounding hypothalamus and thalamus. MRIs performed on control dogs were unremarkable. We then perfused a random selection of four treated and two control dogs and imaged their brains ex vivo prior to sectioning. Ex vivo imaging confirmed the in vivo findings and strongly correlated with both electrophysiologic and subsequent histopathologic findings. Imaging was repeated in the surviving dogs 5 and 12 weeks after discontinuation of dosing. Signal abnormalities in the treated dogs progressively diminished during recovery, paralleling the electrophysiologic and histopathologic results. These findings demonstrate that MRI can detect signal changes anatomically congruent with vigabatrin-induced intramyelinic edema and suggest that MRI may provide a useful noninvasive tool for monitoring patients during clinical trials.

4-Aminobutyrate Transaminase↗
PubMed1992

Pregnancy-associated subacute hemorrhage into a prolactinoma resulting in diabetes insipidus.

A young woman with a small pituitary tumor associated with hyperprolactinemia developed subacute intrapituitary hemorrhage during the third trimester of pregnancy and presented with central diabetes insipidus. Magnetic resonance imaging established the diagnosis. After transsphenoidal surgery, her visual findings resolved, and the patient had an uneventful spontaneous delivery.

Adult↗
PubMed1992

Comparison of vasoconstrictors for functional endoscopic sinus surgery in children.

Three different vasoconstricting agents were evaluated during functional endoscopic sinus surgery (FESS) in 57 children. Oxymetazoline hydrochloride 0.05%, phenylephrine hydrochloride 0.25%, or cocaine 4% was applied to the nasal mucosa in a prospective, randomized, double-blind fashion. Heart rate and blood pressure changes were recorded 5 and 10 minutes after application of the study vasoconstrictor to each nostril. The surgeon's subjective impressions of bleeding and visualization were recorded for each side of the nose, as were total blood loss and anesthesia time. Although all three vasoconstrictors were tolerated well by the children, there was a suggestion that heart rate decreased more at 5 minutes with phenylephrine than with oxymetazoline or cocaine (P = .08) and that blood pressure increased more at 10 minutes with phenylephrine than with oxymetazoline or cocaine (P = .1). No arrhythmias were noted. Subjective scoring for bleeding showed that children receiving oxymetazoline were less likely to receive scores of "more" bleeding than usual (3/38 vs. 10/34 for phenylephrine and 10/35 for cocaine, P less than .02). Subjective scoring for visualization showed that children receiving oxymetazoline were also less likely to receive scores of "worse" visualization than usual (3/38 vs. 12/38 for phenylephrine and 9/35 for cocaine, P less than .01). There was no difference in surgical bleeding or visualization between children receiving phenylephrine and children receiving cocaine. In our institution, 0.05% oxymetazoline is the preferred vasoconstrictor for FESS in children.

Blood Pressure↗
PubMed1991

Sagittal MR images of the knee: a low-signal band parallel to the posterior cruciate ligament caused by a displaced bucket-handle tear.

A low-signal band parallel and anterior to the posterior cruciate ligament has been noted on sagittal MR images of the knee in some patients with other evidence for medial meniscal tears. It was hypothesized that this low-signal band represented the mesially displaced fragment of a bucket-handle tear. To verify this, we retrospectively reviewed MR and arthroscopic findings in 54 consecutive patients. Arthroscopy showed a bucket-handle tear of the medial meniscus in seven patients and was considered diagnostic. Sagittal MR images were reviewed without knowledge of the arthroscopic results. The presence of a curvilinear low-signal band above the tibial cortex anterior, inferior, and parallel to the posterior cruciate ligament was identified on MR images in all seven of the patients in whom the presence of a bucket-handle medial meniscal tear was confirmed by arthroscopy. Our findings suggest that a low-signal band anterior and parallel to the posterior cruciate ligament on sagittal MR images of the knee is caused by a mesially displaced bucket-handle tear of the medial meniscus.

Adult↗
PubMed1990

Severe anaphylactoid reaction after i.v. Gd-DTPA.

Serious adverse reactions following the IV administration of Gd-DTPA (Magnevist, gadopenetate dimeglumine, Berlex Laboratories, Wayne, NJ), although extremely rare, can occur. As yet, there has been no published case of a severe anaphylactoid-type reaction to Gd-DTPA.

Anaphylaxis↗
PubMed1987

Evidence for central nervous system demyelination in chronic inflammatory demyelinating polyradiculoneuropathy.

It is unclear whether sporadic reports of concurrent multiple sclerosis (MS) and chronic inflammatory demyelinating polyradiculoneuropathy (CIDP) represent coincidence or whether these two demyelinating disorders are pathogenically related. We utilized the sensitivity of magnetic resonance imaging (MRI) in detecting central nervous system (CNS) lesions to investigate 16 patients with CIDP. Six of the 16 had periventricular, subcortical, and brainstem white matter lesions indistinguishable from those seen in MS. Three of these patients had definite clinical and laboratory evidence of MS; three others with abnormal MRIs had no findings indicative of CNS disease. Previous reports have indicated that a significant number of MS patients have peripheral nerve demyelination. Our study suggests that many CIDP patients have concurrent CNS demyelination. Taken together, these observations support the existence of a central-peripheral inflammatory demyelinating syndrome. Whether this combined demyelinating syndrome lies on a spectrum between MS and CIDP or is a separate pathogenic entity will require further investigation.

Adult↗
PubMed1987

Hybrid color MR imaging display.

A novel computer-image processing method is described that combines and displays the data from two different MR sequences of the same anatomic slice in a single color image. The pixel intensities from one image are assigned varying spectral hues while the luminance of these hues is derived from the intensities of corresponding pixels of a second spatially aligned image. This technique provides a two-dimensional resolvable contrast scale that may produce images of improved information content. The versatility of the method, termed hybrid color display, is demonstrated by using T1-weighted, T2-weighted, chemical-shift, and gradient-recalled-acquisition-into-steady-state (GRASS) images. This technique may facilitate MR interpretation by enhancing anatomic and pathologic conspicuity and by expediting review.

Color↗
PubMed1986

The knee: surface-coil MR imaging at 1.5 T1.

Seven normal knees (in five volunteers) and seven injured knees (in seven patients) were examined by high-resolution magnetic resonance (MR) imaging at 1.5 T with a surface coil. Seven medial meniscal tears, three anterior cruciate ligament tears, one posterior cruciate ligament avulsion, an old osteochondral fracture, femoral condylar chondromalacia, and one case of semimembranous tendon reinsertion were identified. MR images correlated well with recent double-contrast arthrograms or results of surgery. All tears were identified in both the sagittal and coronal planes. Because of its ability to demonstrate small meniscal lesions and ligamentous injuries readily, MR imaging with a surface coil may eventually replace the more invasive arthrography.

Humans↗
PubMed1986

High-field MR surface-coil imaging of the hand and wrist. Part I. Normal anatomy.

High-resolution magnetic resonance (MR) images of the hands and wrists of six healthy volunteers were obtained at 1.5 T with a surface coil. Additionally, the hands and wrists of two fresh cadavers were imaged and were subsequently sectioned for anatomic correlation. High contrast when depicting soft-tissue, coupled with impressive spatial resolution and multiplanar capabilities, enabled delineation of fine structures including nerves, tendons, and blood vessels. Osseous and cartilaginous structures were also well depicted. MR imaging gives anatomic definition of the hand and wrist unmatched by other diagnostic imaging methods.

Adult↗