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Biomedical subjects

J G Modell

Publications and source records attributed to J G Modell.

32 records · Page 2Linked to original sources
PubMed1990

Prognostication of recovery following stroke using the comparison of CT and technetium-99m HM-PAO SPECT.

This study investigated the possibility that a relationship between the anatomic defects observed on computed tomography (CT) and the functional defects observed on single photon emission computed tomography (SPECT) might be used as an outcome measure to predict clinical recovery from the neurologic deficits induced by stroke. Twenty-seven patients with stroke location limited primarily to cerebral cortex were included in the study: each patient underwent a cranial CT scan, 99mTc hexamethylpropyleneamineoxime SPECT cerebral perfusion scan, and an initial and 1-yr follow-up neurologic examination. A strongly positive correlation between the ratio of the SPECT to CT volume defect sizes (SPECT divided by CT) and recovery following stroke was found, such that the greater the SPECT to CT ratio, the better the subsequent recovery of neurological deficits. Discriminant function analysis revealed that the best predictor of clinical outcome following stroke was the log-transformation of SPECT divided by CT. The results suggest that the relationship between the perfusion defects and tissue loss measured by SPECT and CT imaging may have prognostic utility following stroke limited primarily to cerebral cortex.

Adult↗
PubMed1989

Specific localization of thallium 201 in human high-grade astrocytoma by microautoradiography.

The ability to accurately distinguish remaining or recurrent high-grade astrocytoma from necrosis or edema following treatment is essential to optimal patient management. Thallium 201 planar gamma-camera imaging has been shown to be helpful in detecting recurrent high-grade astrocytoma; however, due to tissue heterogeneity adjacent to and within tumor, the cellular specificity and quantification of 201Tl uptake are largely unknown. In order to determine which tissues are responsible for the radioisotope uptake, microautoradiographic techniques were used to examine multiple tissue sections from five patients with high-grade astrocytoma. Each patient received 5 mCi of 201Tl i.v. 1 h prior to tumor removal. Additionally, all patients received computerized tomographic and 201Tl planar gamma-camera scans prior to surgery. Following surgery, the excised tissue specimens were tentatively classified by gross pathological examination and then immediately processed for dry mount autoradiography; grain density was determined over regions containing tumor, adjacent and uninvolved brain tissue, necrotic tissue, and background. Highly significant differences were found in grain densities (201Tl uptake) between tumor and uninvolved brain tissue, as well as between uninvolved brain tissue and necrotic tissue; there was no significant difference between background grain density and that in necrotic tissue. Mean grain densities (grains/cm2 +/- 1 SD) across patients were: tumor, 102 +/- 23; adjacent, uninvolved brain tissue, 29 +/- 11; necrotic tissue, 6.2 +/- 1.1; and background, 7.0 +/- 4.1. We conclude that the ability of 201Tl to selectively image high-grade astrocytoma is due to its preferential uptake into tumor cells.

Adult↗
PubMed1989

Positron emission tomographic evaluation of cerebral blood flow during state anxiety in simple phobia.

The present study was undertaken to clarify some of the conflicting findings of previous reports on the effect of state anxiety on cerebral blood flow (CBF). Seven subjects with simple phobia of small animals were studied to permit the generation of wide ranges of anxiety. Each subject received five positron emission tomography (PET) scans in a rest-fear-rest-fear-rest, repeated-measures paradigm. A population of eight normal controls was employed. The phobic stimuli produced significant increases in state anxiety during fear and significant differences in physiologic measurements between the fear and rest scans. Absolute global and regional CBF was significantly lower during fear scans than during rest scans; however, when hypocapnia resulting from anxiety-induced hyperventilation was taken into account, the pattern vanished, and all global and regional CBF differences among scans became not significant. Resting global and regional CBF values in the phobic subjects did not significantly differ from those of the normal controls. That a relationship between anxiety and CBF was not found in 35 scans among seven subjects strongly suggests that CBF changes induced by state anxiety are either not presently measurable by PET techniques or that such a relationship may not exist. These findings should also reduce concerns that subject anxiety may confound CBF measurements during routine PET scanning.

Anxiety Disorders↗
PubMed1989

Neurophysiologic dysfunction in basal ganglia/limbic striatal and thalamocortical circuits as a pathogenetic mechanism of obsessive-compulsive disorder.

This article is intended to elucidate some of the neuropathogenetic mechanisms possibly operative in obsessive-compulsive disorder (OCD). Relevant literature is reviewed, with attention to psychologic, and pathologic considerations. Anatomy, neurochemistry, and known functional associations with neuropathological and behavioral abnormalities of implicated brain regions are discussed. The authors propose that dysfunction of neuronal circuits interconnecting the orbitofrontal cortex, basal ganglia/limbic striatum, and thalamus serves a critical role in the pathogenesis of OCD and that obsessive-compulsive symptoms occur when an aberrant positive feedback loop develops in the reciprocally excitatory frontothalamic neuronal interchange, which is inadequately integrated or inhibited by the ventromedial (limbic) portions of the striatum; the ventromedial striatum may serve to modulate activity in the frontothalamic circuit through a negative feedback loop.

Antidepressive Agents, Tricyclic↗
PubMed1989

Dopaminergic activity of the antimuscarinic antiparkinsonian agents.

The antimuscarinic antiparkinsonian agents are widely used in psychiatric practice to reduce the extrapyramidal motor symptoms caused by the neuroleptic antipsychotic medications. Although the antimuscarinic antiparkinsonian agents are effective in reducing extrapyramidal symptoms, their use in conjunction with neuroleptic treatment of psychosis has been reported to antagonize the therapeutic effects of the neuroleptic; there are also several reports of the antimuscarinic antiparkinsonian agents variously causing psychotic syndromes, mood elevating and stimulant effects, stereotypy, dyskinesia, behavioral agitation, and drug dependence in both psychiatric and normal populations. These drug-related phenomena are generally attributed to the antimuscarinic properties of these agents. A large body of data, however, has shown that the antimuscarinic antiparkinsonian agents also function as potent, indirect dopamine-agonists. Benztropine, the most widely prescribed of these medications, is one of the most potent known inhibitors of presynaptic dopamine reuptake. These antiparkinsonian agents also have potent agonist activity at the noradrenergic synapse, as well as minor activity at the serotonergic synapse. This paper reviews neuropharmacologic evidence suggesting that significant neurophysiologic effects can result from the dopaminergic--and possibly noradrenergic--activity of the antimuscarinic antiparkinsonian agents, similar in some cases to those observed with amphetamine. Greater attention to these properties may aid in interpretation of clinical and research observations involving these so-called "antimuscarinic" agents.

Antiparkinson Agents↗
PubMed1985

Inpatient clinical trial of lorazepam for the management of manic agitation.

Antipsychotic medications have traditionally been used for their sedative effects in the management of the behavioral and emotional agitation of mania while awaiting the therapeutic effect of lithium. On the premise that a nonantipsychotic sedative might satisfactorily and more specifically control this agitation without neuroleptic or hypotensive side effects and without prolongation of the acute illness, the authors conducted an open trial with four acutely manic patients in which only the benzodiazepine lorazepam was administered along with lithium; no antipsychotic medications were used. Lorazepam, administered in oral and parenteral form on an as-needed basis to maintain patient cooperation with the treatment plan and milieu, was found to be rapid and effective in controlling the manic agitation of these patients, with few troublesome side effects, and with no obvious prolongation of the acute illness.

Adult↗
PubMedDate not supplied

Breath alcohol values following mouthwash use.

OBJECTIVE: To determine whether breath alcohol values (BrAV) attained following mouthwash use pose a realistic threat to the accuracy of blood alcohol determinations by breath analysis. DESIGN: Nonrandomized, open-label trial. SETTING: Outpatient research office. PARTICIPANTS: Ten normal subjects; convenience sample. INTERVENTIONS: Breath alcohol measurements were made 2, 4, 6, 10, and 15 minutes following rinsing of the mouth with Listerine (26.9% alcohol) [corrected], Scope (18.9% alcohol), and Lavoris (6.0% alcohol) using the Alco-Sensor III intoximeter. MAIN OUTCOME MEASURES: Breath alcohol values over time. RESULTS: Breath alcohol values following mouthwash use decayed exponentially (r2 > or = .98, P < .001) from mean values 2 minutes following mouthwash use of 52.8 mmol/L (240 mg/dL) for Listerine, 37.4 mmol/L (170 mg/dL) for Scope, and 7.9 mmol/L (36 mg/dL) for Lavoris to mean and maximum values after 10 minutes that were well below the usual driving-while-intoxicated range (> or = 17.6 mmol/L [80 mg/dL]) for all three brands. The nonalcoholic mouthwash ingredients did not significantly affect the BrAVs attained. CONCLUSION: The decay of BrAVs following mouthwash use is sufficiently rapid that mouthwash use would not pose a realistic threat to the accuracy of blood alcohol determinations by breath analysis under normal circumstances. Use of mouthwash immediately prior to breath testing, as might occur in the car or workplace in a mistaken attempt to hide the smell of alcohol or other substances, may, however, significantly increase the measured BrAV.

Adult↗