Search PubMed⌕ Search

Biomedical subjects

J Weinberger

Publications and source records attributed to J Weinberger.

At least 73 records · Page 4Linked to original sources
PubMed1990

Steroid sulfatase activity in the skin of the external ear canal.

Steroid sulfatase is an enzyme which has an important role in the complex process of cell desquamation. The specific activity of this enzyme was found to be higher in the epithelium of the deep external auditory canal than in the epithelium of the superficial external canal. We speculate that this steroid sulfatase activity gradient is involved in the outward migration of the keratinocytes of the canal epithelium.

Analysis of Variance↗
PubMed1988

Monoamine neurotransmitters in the evolution of infarction in ischemic striatum: morphologic correlation.

Evolution of infarction following cerebral ischemia is a delayed process, with spongiform degeneration of the neuropil occurring 6 to 8 hours after onset of ischemia. The brains of gerbils with stroke following unilateral carotid artery ligation were examined for catecholamine-derived fluorescence (CADF) by the Falck-Hillarp technique to study the relationship of catecholamine (CA) metabolism with damage to the neuropil. CADF could still be identified in the striatum for up to 16 hours after stroke and there appeared to be spongiform degeneration of the neuropil in relation to accumulations of CADF at 7 and 16 hours after stroke. Pretreatment of gerbils with a-methyl-p-tyrosine 400 mg/kg 6 hours prior to carotid ligation depleted the striatum of CADF until 16 hours after stroke and appeared to reduce the spongiform degeneration of the neuropil, though it did not affect ischemic degeneration of neuronal cell bodies. The continued presence of CADF in the striatum for up to 16 hours after stroke supports the previously reported findings that CA nerve terminals are still functional for 8 hours after stroke and that CA metabolism continues even though levels of CA are reduced immediately after onset of ischemia due to carotid artery ligation.

Animals↗
PubMed1988

Morphologic and dynamic changes of atherosclerotic plaque at the carotid artery bifurcation: sequential imaging by real time B-mode ultrasonography.

Occurrence of new symptoms of focal cerebrovascular disease, including completed cerebral infarction, transient cerebral ischemic attack and amaurosis fugax, was correlated with changes in size and morphology of atherosclerotic plaques at the carotid artery bifurcation visualized by real time B-mode ultrasonography. Bilateral serial images of 246 plaques in 123 patients were made in a time interval of 9 to 35 months between initial and follow-up studies. There was a significantly higher incidence of symptoms ipsilateral to plaques that grew [30 (25%) of 121] than of symptoms ipsilateral to plaques that diminished or remained unchanged [8 (8%) of 98] (p less than 0.001). Plaques that became hemodynamically obstructive by causing disruption of laminar flow or reduction of distal perfusion pressure at the ophthalmic artery were associated with a higher frequency of symptoms [12 (40%) of 30] than were nonobstructive plaques [26 (13%) of 201] (p less than 0.001). There was also a strong association between symptoms and plaque configuration. Mural plaques growing in a crescentic configuration along the wall of the carotid bifurcation between the first and second examination had a higher incidence of symptoms [22 (40%) of 56] than did plaques that grew but maintained a nodular configuration [8 (12%) of 65] (p less than 0.001), although the same proportion of each became hemodynamically obstructive. Sequential visualization of atherosclerotic plaques by real time B-mode ultrasonography of the carotid bifurcation may provide a method for studying the pathogenesis of arterial thrombosis.

Aged↗
PubMed1988

Increase in extracellular dopamine in the striatum during cerebral ischemia: a study utilizing cerebral microdialysis.

Unilateral ligation of the left common carotid artery in anesthetized Mongolian gerbils resulted in a steep rise in extracellular dopamine in the ipsilateral striatum in 9 out of 19 animals. Extracellular dopamine was measured by cerebral dialysis in vivo and reached a peak of 0.19 mM at 40 min. At the same time, the level of homovanillic acid fell, whereas the levels of ascorbate and 3,4-dihydroxyphenylacetic acid remained relatively constant. In a separate group of animals studied with a combined dialysis/electrochemistry probe, a rise in the in vivo chronoamperometric signal in three out of six animals correlated with a rise in extracellular dopamine. The number of animals responding in these experiments (roughly 50%) corresponds to the frequency of incompetent Circle of Willis, as well as literature reports of the frequency of signs of stroke in unanesthetized gerbils. These results show a remarkable accumulation of dopamine in extracellular fluid in response to cerebral ischemia. Released dopamine appears to be responsible for the elevated in vivo electrochemical signal previously reported.

3,4-Dihydroxyphenylacetic Acid↗
PubMed1988

Localization of a repressive sequence contributing to B-cell specificity in the immunoglobulin heavy-chain enhancer.

The immunoglobulin heavy-chain enhancer is a cis-acting element which activates transcription of nearby genes only in cells of the lymphoid lineage. To identify the minimal sequences necessary to impart cell type transcriptional specificity, we tested the activity of several deletions and internal mutations in the mu enhancer. Experiments involving measurement of both chloramphenicol acetyltransferase activity and RNA levels indicated the presence of a dominant repressor element within the mu enhancer. This repressive activity was detected in fibroblasts but not in myeloma cells. Removal or disruption of this repressor element revealed the presence of elements within the mu enhancer that activate transcription in fibroblasts. Thus, enhancer tissue specificity is in part due to the composite of both constitutive activation and cell-type-specific repressive activity. The possible biological roles of this phenomenon are discussed.

Animals↗
PubMed1988

Noninvasive evaluation of the extracranial carotid arteries in patients with cerebrovascular events and atrial fibrillations.

Noninvasive carotid artery testing was performed in 73 patients with nonvalvular atrial fibrillation who were referred because of symptoms or signs of cerebrovascular disease. Thromboembolism related to atrial fibrillation without valvular heart disease was the probable source of cerebral ischemia in 25 (80%) of 31 patients with stroke and coexisting atherosclerotic disease at the carotid artery bifurcation in six (20%). Nonvalvular atrial fibrillation was the probable source of symptoms in nine (70%) of 13 of patients with transient cerebral ischemia, while coexisting carotid artery disease was present in four (30%). Nonvalvular atrial fibrillation accounted for the symptoms in four of five patients with amaurosis fugax, with atherosclerotic carotid artery disease present in one. The remaining 24 patients had nonhemispheric symptoms of cerebrovascular disease, including vertebrobasilar insufficiency, dizziness, and syncope, and only one had a carotid lesion. A significantly higher proportion of patients with focal hemispheric symptoms had coexisting carotid disease than patients with nonfocal symptoms had, suggesting that atherosclerotic cerebrovascular disease contributes to stroke in patients with nonvalvular atrial fibrillation. Noninvasive carotid artery testing may be helpful in identifying atherosclerotic lesions at the carotid artery bifurcation in patients with atrial fibrillation and cerebrovascular disease, because different therapeutic modalities may be appropriate when two potential sources of cerebral ischemia are present.

Atrial Fibrillation↗
PubMed1987

Metabolism of monoamine neurotransmitters in the evolution of infarction in ischemic striatum.

The time course of changes in monoamine metabolism in ischemic striatum was assessed by measurement of levels of dopamine (DA), dihydroxyphenylacetic acid (DOPAC), homovanillic acid (HVA), serotonin (5-HT) and 5-hydroxy-indole-acetic acid (5-HIAA) 2, 4, 7 and 16 hours after irreversible unilateral carotid ligation in Mongolian gerbils with stroke. DA was reduced to 30% of the level in the contralateral non-ischemic striata by 2 hours after stroke, but DOPAC was significantly elevated (p less than 0.01) to 227%, while HVA remained equal to control. At 4 hours after stroke, DOPAC was 86% of the contralateral non-ischemic striata but HVA had risen to 130%. At 7 hours after stroke, DOPAC in the ischemic striata was 148% of control, while HVA remained at 133%. By 16 hours after stroke, DA, DOPAC and HVA were depleted from the ischemic striata, corresponding to the time course for irreversible damage to the neurotransmitter uptake function of nerve terminals. 5-HT levels in the ischemic striata were 30% of control at 2 hours, 46% at 4 hours, 30% at 7 hours and 21% at 16 hours, while 5-HIAA remained equal to control throughout the time course. These studies indicate that monoamine metabolism continues in ischemic striatum for up to 8 hours after the onset of stroke following irreversible unilateral carotid ligation in the Mongolian gerbil, but metabolism of DA is disrupted by 16 hours after stroke while metabolism of 5-HT continues.

3,4-Dihydroxyphenylacetic Acid↗
PubMed1987

Atherosclerotic plaque at the carotid artery bifurcation. Correlation of ultrasonographic imaging with morphology.

Morphologic characteristics of atherosclerotic plaque at the carotid artery bifurcation were compared to the appearance of the plaque on real-time B-mode ultrasonography. Mural plaques propagating along the wall of the carotid sinus had a 72% frequency of recent organizing hemorrhage. Nodular plaques causing local narrowing of the vessel had only a 23% incidence of organizing hemorrhage. This difference was significant (P less than 0.01). The presence of recent organizing hemorrhage in mural plaques may account for the increased frequency of symptoms previously observed to occur ipsilateral to mural plaques compared to nodular plaques.

Arteriosclerosis↗
PubMed1985

Clinical applications of noninvasive carotid artery testing.

The management of patients with cerebral transient ischemic attacks and carotid artery stenosis remains controversial. Noninvasive techniques help to determine which patients require surgical intervention without exposing the majority of patients to the risk and discomfort of invasive procedures. Measurement of ophthalmic artery pressure by ophthalmodynamometry or oculoplethysmography gives a representation of perfusion pressure in the internal carotid artery circulation. Doppler ultrasound studies can define the extent of obstruction to flow at the carotid artery bifurcation and assess collateral flow from the external carotid artery. Real time B-mode ultrasonography can detect nonobstructive ulcerated plaque in the carotid artery bifurcation. Employing these examinations in a test battery can identify hemodynamically significant lesions, which are more likely to precipitate a stroke. The information obtained from these studies can be utilized in patients with episodes of cerebral transient ischemic attacks, asymptomatic carotid artery bruits and vertebrobasilar insufficiency. Noninvasive carotid artery testing is also useful in screening patients with nonspecific symptoms, such as dizziness or light-headedness, which may be related to decreased flow in the carotid circulation. Noninvasive carotid artery testing can provide valuable anatomic and physiologic information required in the appropriate management of patients with cerebrovascular disease. It is of particular value in managing patients with heart disease who are at high risk for complications from invasive procedures.

Arteriosclerosis↗
PubMed1985

Hamartoma of the larynx.

A patient with a small mass occupying the laryngeal ventricle is reported. The rare histological diagnosis of an epithelial hamartoma is discussed, with reference to the other sites of occurrence in the head and neck.

Biopsy↗
PubMed1984

Cerebral hemodynamics in the diagnosis of normal pressure hydrocephalus.

We studied the effect of CSF drainage on cerebral blood flow (CBF) in normal pressure hydrocephalus (NPH) and non-NPH dementia using the 133Xenon inhalation technique. Dementia patients had lower CBF than matched elderly normals. Flow values for NPH and non-NPH patients did not differ before or after CSF drainage. CBF did not increase after lumbar puncture, and these measurements were not useful in predicting the outcome of ventricular shunt surgery. Postoperative CBF did not increase after successful shunting.

Cerebrospinal Fluid Shunts↗
PubMed1983

Neurologic symptoms associated with nonobstructive plaque at carotid bifurcation. Analysis by real-time B-mode ultrasonography.

Real-time B-mode ultrasonography was employed to image nonobstructive atherosclerotic plaque formation in the carotid artery bifurcation. Hemodynamic factors were assessed by pneumo-oculoplethsymography and Doppler flow study. Hemodynamically obstructive lesions were associated with a significantly higher incidence of cerebral ischemic symptoms than were nonobstructive plaques. Two types of nonobstructive plaques were delineated: isolated nodular plaques and mural plaques along the wall of the carotid sinus. Nodular plaques were associated with significantly fewer ischemic symptoms and strokes than were obstructive lesions. Mural plaques also had a lower incidence of symptoms than obstructive lesions, but the difference was not significant. Noninvasive determination of the morphologic and physiologic characteristics of atherosclerotic lesions at the carotid bifurcation can be of considerable value in the management of patients with transient ischemic attacks.

Adult↗
PubMed1983

Premonitory symptoms of stroke in evolution to the locked-in state.

Three patients, who subsequently developed the locked-in state characterised by quadriplegia and mutism with an alert sensorium, initially had mild dysarthria and uncrossed hemisensory or hemimotor deficits involving the face and ipsilateral extremities. Case one initially mimicked a left cerebral lesion with right hemisensory deficits, a mild right facial paresis and a right homonymous field deficit. Case two initially developed both left hemimotor and hemisensory deficits and later developed a paresis of right conjugate gaze. Case three presented with left hemimotor deficit, and mild paresis of conjugate gaze to the right. All three patients died. Rostral brainstem infarctions were found at necropsy in cases one and two. Case three had a radiolucent area of the brainstem demonstrated by CT Scan. Hemisensory and hemimotor deficits also have been noted to precede reported cases of pontine infarction with the locked-in state. Acute onset of uncrossed hemisensory and hemimotor deficits with dysarthria may be caused by infarction of the pons which may predispose to the locked-in state.

Aged↗