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Biomedical subjects

M S Levine

Publications and source records attributed to M S Levine.

At least 37 records · Page 2Linked to original sources
PubMed2001

Delayed postnatal development of NMDA receptor function in medium-sized neurons of the rat striatum.

During early postnatal development, the N-methyl-D-aspartate (NMDA) subtype of glutamate receptor plays a dominant role in excitatory amino acid-mediated synaptic transmission in essentially every brain region that has been examined. In contrast, we have found that in the rat striatum, NMDA receptor-mediated current develops later in the medium-sized neurons (MSNs) than currents mediated by activation of non-NMDA receptors. MSNs were identified using infrared video microscopy, and voltage-clamped in a slice preparation using the whole-cell patch-clamp technique. Intrastriatal stimulation was used to evoke excitatory synaptic currents from slices in animals ranging in age from postnatal day (PND) 5 to 60. Though most cells from animals younger than PND 10 failed to respond to synaptic stimulation, postsynaptic responses were occasionally evoked in cells as young as PND 5. Synaptic currents from cells between PNDs 5 and 7 had a significant contribution due to activation of non- NMDA receptors, as evidenced by sensitivity to the non-NMDA receptor antagonist 6-cyano-7-nitroquinoxaline-2,3-dione and rapidly rising and falling response components. The relative contribution of NMDA receptors increased approximately twofold from the first to the third postnatal week; no further change was observed through PND 60. At the same ages that the NMDA receptors contributed maximally to the synaptic current, the decay time constant of the NMDA receptor-mediated current decreased significantly. The increasing weight of NMDA receptor-mediated current may reflect a change in the number of functional receptors at the synapse since there was no apparent change in the voltage dependence of the current. To more completely examine receptor function early in postnatal development, NMDA and kainate were applied either iontophoretically or in the bath. Iontophoretic application of NMDA onto cells obtained from rats between PNDs 3 and 5 only occasionally evoked current, provided that the membrane was held at depolarized potentials to remove the Mg(2+) block. In contrast, application of kainate consistently evoked a response from cells of the same age group. Bath application of the same agonists provided similar results. Taken together, the present experiments demonstrate that striatal non-NMDA receptor-mediated currents are more mature than NMDA receptor-mediated currents early in development.

2-Amino-5-phosphonovalerate↗
PubMed2001

Short-segment Barrett's esophagus: findings on double-contrast esophagography in 20 patients.

OBJECTIVE: The purpose of this study was to determine the findings of short-segment Barrett's esophagus on double-contrast esophagography. MATERIALS AND METHODS: A review of pathology and endoscopy data revealed 142 patients with short-segment Barrett's esophagus, which was defined as columnar epithelium in the distal esophagus extending 3 cm or less above the gastroesophageal junction at endoscopy with histopathologic confirmation of intestinal metaplasia. Twenty of these patients underwent double-contrast esophagography. These 20 patients comprised our study group. The original radiology reports and images were reviewed to determine the findings on double-contrast esophagography. Medical records were also reviewed to determine the clinical findings and treatment. RESULTS: Double-contrast esophagrams revealed hiatal hernias in 18 patients (90%), gastroesophageal reflux in 16 (80%), reflux esophagitis in seven (35%), peptic scarring or strictures in 11 (55%), and a reticular mucosal pattern in none. A total of 14 patients (70%) had morphologic findings of reflux disease with esophagitis alone (three patients), peptic scarring or strictures alone (seven patients), or both (four patients), but the remaining six (30%) had hiatal hernias or gastroesophageal reflux as the only radiographic finding. CONCLUSION: Double-contrast esophagography revealed morphologic findings of reflux disease with esophagitis, peptic scarring or strictures, or both in 70% of patients with short-segment Barrett's esophagus. Thus, the absence of esophagitis or peptic scarring or strictures on double-contrast esophagography does not exclude the possibility of short-segment Barrett's esophagus.

Adult↗
PubMed2001

Congenital esophageal stenosis in adults: clinical and radiographic findings in seven patients.

OBJECTIVE: The purpose of this study was to determine the clinical and radiographic findings in seven adults with congenital esophageal stenosis. CONCLUSION: In young or middle-aged individuals, particularly men with long-standing dysphagia, an upper or mid esophageal stricture with multiple ringlike constrictions is a characteristic appearance of congenital esophageal stenosis on double-contrast esophagography.

Adult↗
PubMed2001

Visualization of areae gastricae on double-contrast upper gastrointestinal radiography: relationship to age of patients.

OBJECTIVE: The purpose of this study was to determine whether the frequency of visualization of areae gastricae on double-contrast upper gastrointestinal tract examinations is related to a patient's age. MATERIALS AND METHODS: A total of 141 double-contrast upper gastrointestinal tract examinations with normal findings were reviewed for the presence or absence of areae gastricae on double-contrast images of the stomach. All images were evaluated by two radiologists who were blinded to the age of the patients. The data were then analyzed to determine if the frequency of visualization of areae gastricae on double-contrast studies was significantly related to the age of patients. RESULTS: The frequency of visualization of areae gastricae increased significantly with increasing age (p = 0.008). The youngest age group (20--29 years old) exhibited areae gastricae in only four (19%) of 21 cases, whereas the oldest age group (> or = 70 years old) exhibited areae gastricae in 19 (76%) of 25 cases. On average, the rate of visualization of areae gastricae on double-contrast studies increased by 9% per decade. CONCLUSION: Our data show that the frequency of visualization of areae gastricae on double-contrast upper gastrointestinal tract examinations increases significantly with increasing patient age. It is important for radiologists to be aware of the effect of aging on the delineation of areae gastricae on double-contrast studies.

Adult↗
PubMed2001

Lymphoid hyperplasia of the stomach: radiographic findings in five adult patients.

OBJECTIVE: The purpose of our study was to report the radiographic findings of biopsy-proven lymphoid hyperplasia of the stomach in five adult patients. CONCLUSION: Lymphoid hyperplasia of the stomach is characterized by distinctive findings on double-contrast upper gastrointestinal tract barium examinations; all five patients had innumerable tiny (1--3 mm in diameter) round frequently umbilicated nodules that carpeted the mucosa of the gastric antrum or antrum and body. Three of these five patients had associated Helicobacter pylori gastritis. The diagnosis of gastric lymphoid hyperplasia, therefore, can be suggested on the basis of the radiographic findings.

Adult↗
PubMed2001

Killian-Jamieson diverticula: radiographic findings in 16 patients.

OBJECTIVE: The purpose of this study was to reassess the findings of Killian-Jamieson diverticula (i.e., proximal lateral cervical diverticula) on pharyngoesophagograms and to compare the prevalence, clinical findings, and radiographic findings of Killian-Jamieson diverticula with those of Zenker's diverticulum. MATERIALS AND METHODS: A computerized search of radiology files revealed 16 patients with Killian-Jamieson diverticula and 26 patients with a Zenker's diverticulum. The double-contrast pharyngoesophagograms and medical records were reviewed retrospectively. RESULTS: Only three (19%) of 16 patients with Killian-Jamieson diverticula had symptoms attributable to the diverticula (suprasternal dysphagia in two and cough in one), and none had aspiration pneumonia. In contrast, 16 (62%) of 26 patients with a Zenker's diverticulum had suprasternal dysphagia and three patients (12%) had aspiration pneumonia. Twenty Killian-Jamieson diverticula were detected on pharyngoesophagograms in 16 patients, including 12 (75%) with unilateral left-sided diverticula and four (25%) with bilateral diverticula. The Killian-Jamieson diverticula had an average maximal dimension of 1.4 cm. Zenker's diverticulum was nearly four times as common as Killian-Jamieson diverticula and had an average maximal dimension of 2.5 cm. Three patients (11%) with a Zenker's diverticulum had reflux of barium from the diverticula into the hypopharynx with overflow aspiration. Finally, gastroesophageal reflux was detected in nearly twice as many patients with a Zenker's diverticulum as with Killian-Jamieson diverticula. CONCLUSION: Killian-Jamieson diverticula are less common and smaller than Zenker's diverticulum. Killian-Jamieson diverticula are less likely to cause symptoms and are less likely to be associated with overflow aspiration or gastroesophageal reflux than is Zenker's diverticulum.

Adult↗
PubMed2001

Radiographic findings and complications after surgical or endoscopic repair of Zenker's diverticulum in 16 patients.

OBJECTIVE: The purpose of our study was to reassess the radiographic findings and complications associated with surgical or endoscopic repair of Zenker's diverticulum. MATERIALS AND METHODS: Sixteen patients who underwent various procedures for repair of Zenker's diverticulum (diverticulectomy and cricopharyngeal myotomy in [n = 8], diverticulopexy and cricopharyngeal myotomy [n = 4], endoscopic stapling diverticulotomy [n = 3], and cricopharyngeal myotomy alone [n = 1]) had radiographic studies with water-soluble contrast material, barium, or both during the early postoperative period (n = 7), late postoperative period (n = 4), or both (n = 5). The radiologic reports and images were reviewed to determine the postoperative findings and complications associated with surgical or endoscopic repair of Zenker's diverticulum. RESULTS: Radiographic studies revealed leaks during the early postoperative period in three (27%) of 11 patients after surgical repair of Zenker's diverticulum and in zero of three patients after endoscopic diverticulotomy. Pharyngeal dysfunction (pharyngeal paresis, decreased epiglottic tilt, laryngeal penetration, or tracheobronchial aspiration) was detected in seven (54%) of 13 patients after surgery and in one (33%) of three patients after endoscopic diverticulotomy; five of these eight patients had follow-up barium studies during the late postoperative period, and all five showed marked improvement in pharyngeal function. An extrinsic cricopharyngeal impression was detected in six (38%) of these 16 patients, a remnant diverticulum in four (25%), and mucosal beaking in three (19%). A suspended or inverted diverticulum was detected in one of the four patients who underwent surgical diverticulopexy. CONCLUSION: Radiologists should be aware of the various postoperative findings and complications associated with surgical or endoscopic repair of Zenker's diverticulum so that appropriate interventions can be taken in patients with this condition.

Adult↗
PubMed2000

Inactivation of Hdh in the brain and testis results in progressive neurodegeneration and sterility in mice.

Inactivation of the mouse homologue of the Huntington disease gene (Hdh) results in early embryonic lethality. To investigate the normal function of Hdh in the adult and to evaluate current models for Huntington disease (HD), we have used the Cre/loxP site-specific recombination strategy to inactivate Hdh expression in the forebrain and testis, resulting in a progressive degenerative neuronal phenotype and sterility. On the basis of these results, we propose that huntingtin is required for neuronal function and survival in the brain and that a loss-of-function mechanism may contribute to HD pathogenesis.

Alleles↗
PubMed2000

Neurons recorded from pediatric epilepsy surgery patients with cortical dysplasia.

PURPOSE: Cortical dysplasia (CD) is a common pathological substrate in patients with early-onset childhood epilepsy. In CD tissue, little is known about the mechanisms responsible for cellular hyperexcitability. In this study, we report initial electrophysiological and morphological observations from normal and dysmorphic cells in pediatric CD patients. METHODS: Neocortical "most" and "least" epileptogenic areas were sampled based on neuroimaging and electrocorticography from 15 CD patients (ages 0.3 to 14 years). Whole-cell voltage clamp recordings combined with infrared videomicroscopy sampled abnormal cells (cytomegalic neurons, cells with bifurcated dendrites, disoriented pyramidal cells, etc.) compared with normal-appearing neurons from the same patient. Cells were filled with biocytin, and adjacent tissue blocks were stained for neuronal and glial markers. RESULTS: About 15% of the 161 recorded cells were abnormal in appearance. Abnormal cells showed electrophysiological irregularities ranging from intrinsic cellular hyperexcitability to hyposensitivity after application of ionotropic receptor agonists. Other findings included increased excitatory postsynaptic currents and alterations in gamma-aminobutyric acid reversal potentials. CONCLUSIONS: In pediatric CD tissue, these preliminary results indicate that abnormal-appearing cells showed abnormalities in electrophysiological measures compared with normal-appearing neurons. The abnormalities varied from hyperexcitability to hypoexcitability. More detailed results and conclusions will be forthcoming as additional patient material is analyzed.

Adolescent↗
PubMed2000

Congenital esophageal stenosis in adults.

OBJECTIVE: Congenital esophageal stenosis is thought to be a rare disease confined to infancy and childhood with only a few case reports in adults described. METHODS: We report five patients between the ages of 19 and 46 yr who presented with this disorder over a 2-yr period. RESULTS: Patients had been labeled with reflux strictures, webs, or as idiopathic in the past. All patients had chronic solid food dysphagia, some since early childhood. The location of the stricture varied, occurring in the mid or proximal esophagus in four, but throughout the esophagus in one. Radiographic and endoscopic appearance was a smooth concentric stricture or multiple rings, sometimes tracheal in appearance. Endosonography was performed in two patients, both of whom had focal circumferential hypoechoic wall thickening with disruption of the normal layer pattern corresponding to the areas of luminal narrowing. All patients dilated had good symptomatic response, with resolution of symptoms up to 6 months in follow-up. CONCLUSIONS: We suggest that congenital esophageal stenosis does occur in adults and may be underrecognized. Its endosonographic appearance is described.

Adult↗
PubMed2000

Ileal endometriosis: radiographic findings in five cases.

PURPOSE: To determine the radiographic findings in five patients with ileal endometriosis. MATERIALS AND METHODS: A search of radiology files revealed five patients with surgically proved endometriotic implants in the ileum at enteroclysis (three patients), at small-bowel follow-through (one patient), and at double-contrast barium enema study (one patient). The radiographic findings were reviewed retrospectively. Clinical, surgical, and histopathologic findings were also reviewed. RESULTS: All five patients were nulliparous women (mean age, 34.4 years; age range, 28-41 years). Four patients presented with abdominal and/or pelvic pain, but only one of these four had cyclic pain that coincided with menstruation. Barium studies revealed endometriotic implants in the terminal ileum within 10 cm of the ileocecal valve in four patients and in the mid-ileum in one. The radiographic findings consisted of extrinsic mass effect with variable spiculation and tethering of folds in two patients, annular lesions with spiculated folds and abrupt or tapered borders in two, and a plaque-like lesion in one. In four patients who underwent double-contrast barium enema studies, associated endometriotic implants were found in the rectosigmoid colon. CONCLUSION: Ileal endometriosis usually involves the terminal ileum within 10 cm of the ileocecal valve and manifests as a spectrum of findings on barium studies. Ileal endometriosis should therefore be considered when these findings are present in young, nulliparous women with abdominal or pelvic pain.

Abdominal Pain↗
PubMed2000

Double-contrast barium enema examination technique.

This review article presents the principles for performing a safe, comfortable, and accurate double-contrast barium enema examination. The procedure is a flexible examination in which the fluoroscopist interacts with the patient, the controls of the fluoroscope, and the image on the television monitor. During a double-contrast examination, images of the colon are created by manipulating the patient, the barium pool, and the amount of air insufflated into the rectum. Fluoroscopy is essential for guiding the radiologist to obtain spot images with adequate technical factors. The fluoroscopist analyzes the luminal contour, the barium-coated mucosal surface en face, and the barium pool to detect abnormalities in the colon. With careful technique, a high-quality examination can be performed in most patients.

Barium Sulfate↗
PubMed2000

Diagnosis of colorectal neoplasms at double-contrast barium enema examination.

The double-contrast barium enema examination has been recognized as an option for colorectal cancer screening in Americans with average risk who are greater than 50 years of age. The purpose of this article is to review the principles for diagnosing colorectal neoplasms on double-contrast images and the spectrum of findings associated with these lesions. Colonic polyps can be sessile or pedunculated; their appearance depends on whether they are located on the dependent or nondependent wall of the bowel. Villous tumors may be flat, lobulated lesions, also known as "carpet" lesions, that are characterized by a finely nodular or reticular surface pattern, without a discrete mass. Colonic carcinomas may manifest as plaquelike, polypoid, semiannular ("saddle") or annular lesions. Colonic neoplasms sometimes are more difficult to detect in the region of the ileocecal valve or the distal rectum or in patients with severe diverticulosis. Careful double-contrast technique and meticulous scrutiny of the images therefore are required to optimize detection of these lesions.

Barium Sulfate↗
PubMed2000

Striatal ionotropic glutamate receptor ontogeny in the rat.

Rat striatal N-methyl-D-aspartate (NMDA), alpha-amino-3-hydroxy-5-methyl-4-isoxazole propionic acid (AMPA) and kainate (KA) receptor staining were evaluated postnatally in the rat. Immunohistochemistry was used to detect subunit proteins of the three glutamate receptor subtypes. The glutamate receptors displayed distinct developmental expression patterns in the striatum. Morphological distributions for the NMDA R1 subunit (representative of NMDA receptors), Glu R1 and Glu R2/3 subunits (indicative of AMPA receptors), and Glu R5/6/7 subunits (demonstrating KA receptors) attained adult expression patterns and levels at different postnatal time points. The ontogenic maturation sequence of striatal glutamate receptor expression was KA, then AMPA and lastly NMDA. Staining patterns for NMDA and AMPA subunit proteins were detected initially as dense patches in the neuropil, which changed to a homogeneous stain of the striatum by the second week of life. Cellular staining for the three subtypes was intense within the highly reactive neuropil patches, but less intensely stained in neurons located outside these zones. The KA receptor subunit did not exhibit neuropil heterogeneity, but was distributed evenly at birth. All three glutamate receptor subtypes were visible within the striatal neuron populations. Populations of striatal neurons that expressed the three differential glutamate receptor subtypes overlap, exhibit different growth patterns and dendritic staining. These results support a functional emergence of different glutamate receptor activation within the striatum and provide a potential therapeutic means to isolate developmental disorders specifically associated with excitatory circuits of the basal ganglia.

Age Factors↗