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Biomedical subjects

M Hennerici

Publications and source records attributed to M Hennerici.

At least 181 records · Page 10Linked to original sources
PubMed1988

Pulsed Doppler assessment of innominate artery obstructive diseases.

In 14 patients with severe stenosis or occlusion of the innominate artery a new high-energy, low-frequency (2 MHz) pulsed Doppler ultrasound method was used to investigate blood flow velocity patterns of both intrathoracic and intracranial cerebral arteries. Direct acquisition and evaluation of the innominate artery at its origin near the aortic arch enabled separation of it from adjacent arteries and reliable differentiation of stenosis from occlusion. Transcranial recordings from the basal cerebral arteries showed abnormal Doppler signals in 12 patients (86%). Among these abnormalities, observation of a latent steal phenomenon was closely related to the prevalence of cerebrovascular events. This latent steal phenomenon was characterized by a transient reduction of orthograde blood flow in the ipsilateral anterior, middle, and posterior cerebral arteries or in the basilar artery during postischemic hyperemia of the upper extremities. The predictive value of the latent steal phenomenon for the management and follow-up of asymptomatic patients with severe innominate artery obstructions is discussed.

Adult↗
PubMed1988

The subclavian steal phenomenon: a common vascular disorder with rare neurologic deficits.

Three hundred twenty-four patients with reversed vertebral artery blood flow were reviewed for cerebrovascular events. Neither the presence nor the type of vertebral artery steal (permanent, n = 204; intermediate, n = 120) determined neurologic symptoms, which rather were related to coincidental carotid obstructions or abnormal flow velocity patterns in the basilar artery. Most patients (n = 209; 64%) had no neurologic symptoms. Hemispheric events (n = 99; 31%) occurred most frequently in patients with additional carotid lesions and nonhemispheric events in a few patients (n = 16; 5%) often with bilateral vertebral steal. Intracranial Doppler studies from the vertebral and basilar arteries excluded spontaneous retrograde basilar artery perfusion in any of a subgroup of 50 patients examined in addition. Thus, blood flow reversal in extracranial arteries is a marker for atherosclerotic vascular disease in general, rather than an indicator of a patient's risk to develop cerebrovascular events from hemodynamic insufficiency in the territory affected. Surgical treatment is discouraged for most patients with this benign flow abnormality.

Aged↗
PubMed1987

Transcranial Doppler ultrasound for the assessment of intracranial arterial flow velocity--Part 2. Evaluation of intracranial arterial disease.

Transcranial (TC) pulsed Doppler ultrasound was used to evaluate flow velocity within the intracranial basal cerebral arteries in 71 patients with cerebrovascular disease as revealed by arteriography. Abnormalities of the fast-Fourier transformed (FFT) Doppler spectra were used to detect and classify obstructive lesions as well as dilative arteriopathy of the carotid siphon, the middle, anterior, and posterior cerebral arteries, and the basilar artery. Functional stenosis due to large shunting volumes in patients with arteriovenous malformations and in the presence of significant collateralization of extracranial obstructive lesions were similarly diagnosed.

Blood Flow Velocity↗
PubMed1987

Transcranial Doppler ultrasound for the assessment of intracranial arterial flow velocity--Part 1. Examination technique and normal values.

We present the examination technique and normal values of flow velocity from intracranial basal cerebral arteries for a recently developed pulsed Doppler system operating at 2 MHz emitting frequency. Peak systolic, peak diastolic, and mean flow velocity values are analyzed from fast-Fourier transformed (FFT) Doppler spectra at selected depths for 50 presumed normal subjects ranging in age from 22 to 79 years. Interindividual variation is high for peak flow but moderate for mean flow velocity values, which hence are more likely to discriminate normal from abnormal. Flow velocity values within the posterior cerebral artery (PCA) and the basilar artery (BA) are significantly lower than in the anterior cerebral artery (ACA) and the middle cerebral artery (MCA), which is also unique in showing significantly decreasing values with increasing age: calculated mean flow velocities are 47.3 +/- 13.6 and 45.3 +/- 13.5 cm/sec in the ACA, and 58.4 +/- 8.4 and 44.7 +/- 11.1 cm/sec in the MCA in patients less than 40 years and greater than 60 years, respectively, but 34.2 +/- 7.8 and 29.9 +/- 9.3 (PCA) (patients less than 40 years and patients greater than 60 years), and 34.9 +/- 7.8 and 30.5 +/- 12.4 (BA) (patients less than 40 years and patients greater than 60 years). A new scanning system is introduced, which we suggest will reduce interindividual variations and improve the accurate separation of nearby vessels, which are major causes for the comparatively large standard deviations at present.

Adult↗
PubMed1987

The role of subclavian-carotid transposition in surgery for supra-aortic occlusive disease.

From 1977 through 1985, 1043 patients underwent operation for supra-aortic occlusive disease. One hundred thirty-four of these patients (13%) with 146 lesions of the aortic arch branches (innominate, 25; subclavian, 103; and multiple, 10) had one or more symptoms of subclavian steal (78%), transient ischemic attacks (37%), arm ischemia (37%), and others (7%). However, according to results of a critical prospective neurologic examination, the classic steal syndrome appeared in only 13 patients (10%), vertebrobasilar insufficiency in 32 patients (24%), and hemispheric symptoms in 48 patients (36%). Symptomatic and/or significant internal carotid occlusive disease was present, ipsilateral in 28% and contralateral in 31% of the patients. Other supra-aortic vessels were involved in 49% of the patients. During the same period 192 patients with supra-aortic occlusive disease were treated without surgical intervention for various reasons. Fifty-five patients (27%) were completely asymptomatic except for the presence of reversed flow within the vertebral artery. The surgical approach in 138 operations was extrathoracic (ET) in 71% of patients (innominate artery, 2; subclavian artery, 95; and arch syndrome, 1) and transthoracic (TT) in 29% of patients (innominate artery, 23; subclavian artery, 8; and arch syndrome, 9). Generally, bypass procedures were preferred, but for 72 (71%) of the subclavian lesions subclavian-carotid transposition (SCT) was performed. Three patients had been referred for complications of previous carotid-subclavian bypass. The grafts were removed and vertebral and arm circulation restored by SCT. Carotid end-arterectomy was performed simultaneously (20%) or staged (3%) in 8% of the innominate procedures and 25% of the subclavian reconstructive procedures.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1987

Natural history of asymptomatic extracranial arterial disease. Results of a long-term prospective study.

The natural history of asymptomatic extracranial arterial disease (EAD) was studied prospectively in 339 patients admitted for serial ultrasound Doppler examinations. Annual mortality was high at 7%, but stroke mortality was low at 0.6%: 82 patients (24%) died during the follow-up period, which lasted up to seven years (median: 29 months), only 10 from stroke but 41 from cardiac causes. The risk of suffering a stroke without premonitory transient ischaemic attacks (TIAs) was similarly low at 0.4%. Progression of EAD was the only predictor established to indicate the individual patient's cerebrovascular prognosis among a series of criteria tested (age, sex, degree and extent of carotid and/or vertebral disease, risk factors and indicators of atherosclerosis). Deterioration of EAD was observed in 108 (36%) of 296 patients by repeated Doppler examination, 174 (59%) remained constant and 14 (5%) showed an improvement. The observed low rate of strokes without premonitory TIAs is not in favour for early carotid endarterectomy in the majority of neurologically asymptomatic patients.

Adult↗
PubMed1986

Event-related potentials in patients with Huntington's disease and relatives at risk in relation to detailed psychometry.

Event-related potentials (ERPs) were studied in patients with Huntington's disease (HD) and their offspring at risk in a simple auditory oddball paradigm requiring the counting of the rarer of two stimulus categories. Group statistical analysis revealed prolongation of latencies of components P2, N2 and especially P3 in HD patients and to a lesser extent in at-risks. In a large population of normals the age-latency relationship for component P3 showed a non-linear shape with increasing slope and scatter in the older age groups. A bipartate linear regression analysis splitting the normal population at age 50 was used for detection of abnormalities of P3 latency in individual cases. Abnormal P3 latencies were present in the majority of HD patients and also in 25% of clinically normal at-risks. Correlation analysis of ERP components with detailed psychometry revealed a particularly high association of P3 latencies with measurements requiring speeded information processing in non-verbal tasks. P3 amplitude did not covary with performance scores but unlike P3 latency showed association with depression and psychosis scores. From the results it appears that analysis of ERPs is a useful electrophysiological tool for an objective assessment of cognition both in clinically definite and subclinical stages.

Adolescent↗
PubMed1986

Noninvasive transcranial Doppler ultrasound in intracranial angiomas.

Transcranial Doppler ultrasound is a noninvasive method to evaluate flow velocities in the basal cerebral arteries. It can provide hemodynamic data like velocity distributions, intracranial steal phenomena, and functional stenoses in angiomas as illustrated in four patients. This information may supplement conventional neuroradiologic procedures for therapeutic decisions and follow-up.

Adolescent↗
PubMed1986

Stimulation of the scavenger receptor on monocytes-macrophages evokes release of arachidonic acid metabolites and reduced oxygen species.

Mouse peritoneal macrophages are endowed with a scavenger receptor recognizing modified low density lipoproteins (LDL). Metabolic sequelae of receptor occupancy distinct from lipoprotein processing were examined. Adherent peritoneal macrophages were kept in short term culture. Release into culture supernatants of the arachidonic acid derived eicosanoids prostaglandin E, 6-keto-prostaglandin F1a, thromboxane B2, and leukotriene C4 was assessed, and production of reduced oxygen species superoxide anion and hydrogen peroxide, generated in the oxidative burst, was monitored after challenge of macrophages with acetylated or malondialdehyde modified LDL. Modified LDL at concentrations ranging from 50 to 250 micrograms of protein/ml was noted to augment macrophage arachidonic acid metabolism within 6 hours of addition. Cyclo-oxygenase derivatives were synthesized predominantly, but leukotriene C4 generation was also observed. Further, scavenger receptor occupation triggered the release of superoxide anion and hydrogen peroxide which was more rapid in onset and plateaued after 60 minutes of incubation. Human monocyte-derived macrophages, after 4 days in culture, also generated reduced oxygen species and eicosanoids in response to modified LDL. Along with our previous finding of scavenger receptor mediated lysosomal enzyme liberation, the present study indicates novel functions of these binding sites. Our observations may shed new light on the possible role of monocyte-macrophages in atherogenesis.

Animals↗
PubMed1985

Chemically modified low density lipoproteins as inducers of enzyme release from macrophages.

Macrophages carry receptors on their surface for acetylated low density lipoprotein (ac-LDL). Receptor-mediated endocytosis of ac-LDL is followed by intracellular cholesterol accumulation. We investigated whether occupation of these binding sites evokes the release of hydrolytic enzymes from mouse peritoneal macrophages cultured for up to 48 h. ac-LDL at concentrations ranging from 25-250 micrograms protein/ml was noted to promote in a dose-dependent fashion secretion of the neutral proteinase elastase (EC 3.4.21.37) and the lysosomal acid hydrolases N-acetyl-beta-glucosaminidase (EC 3.2.1.30), beta-glucuronidase (EC 3.2.1.31), beta-galactosidase (EC 3.2.1.23), alpha-mannosidase (EC 3.2.1.24) and cathepsin D (EC 3.4.23.5). This stimulatory effect was non-cytotoxic. LDL modified by treatment with malondialdehyde was also capable of augmenting enzyme liberation into culture supernates. These findings may have implications for some aspects of the atherosclerotic process.

Acetylation↗
PubMed1985

Spontaneous progression and regression of small carotid atheroma.

A specially designed high-resolution (10 MHz) ultrasound duplex-system was used to study prospectively the appearance of 43 extracranial non-stenotic carotid plaques (less than 30% lumen narrowing) in 31 patients over 18 months. 13 presented with ipsilateral and 9 with contralateral cerebrovascular events; 9 were asymptomatic. Most carotid atheromas remained unchanged (51%) or progressed (30%), but spontaneous regression was seen in 19% at regular 3 monthly re-examination. Regression was restricted to volume reduction of soft plaques and healing of ulcerative lesions; fibrous and hard plaques remained unchanged or progressed. Intraplaque haemorrhage was only observed in 3 instances and was always associated with later progressive encroachment. Comparison of bilateral plaques in the same individual suggested a uniform advance with duration of the atherosclerotic process. None of the patients had cerebrovascular events during follow-up.

Adult↗
PubMed1985

Dissociated foveal and parafoveal visual evoked responses in subacute combined degeneration.

In four patients with subacute combined degeneration, clinically silent involvement of the visual pathways was demonstrated by visual evoked responses following selective foveal and parafoveal stimulation. The characteristic distribution of the lesion is different from that generally found in patients with multiple sclerosis, and affects slow- and fast-conducting fibers in an opposite manner.

Aged↗
PubMed1985

Evoked potentials in patients with Huntington's disease and their offspring. II. Visual evoked potentials.

Visual evoked potentials (VEPs) to full-field and half-field stimulation were recorded in a large sample of patients with Huntington's disease (n = 36) and subjects at risk (first-order offspring, n = 55) using a checkerboard pattern reversal stimulus. Whereas a clear diminution of the amplitudes found confirmed earlier findings in patients with Huntington's disease, further alterations of VEP wave forms consisted in the absence of asymmetric hemisphere lateralization to half-field stimulation (i) and severe distortion with amplification of the early NPN/PNP complexes (ii). Considering at least two different abnormal parameters necessary to represent a reliable indicator of the disease, 24 patients (67%) and 14 (25%) of the persons at risk exhibited pathological results. In contrast, only 2 among 36 patients (5%) but 30 (55%) among the offspring exhibited normal results. The diagnostic and predictive value of the investigation of VEPs in Huntington's disease is discussed.

Adolescent↗
PubMed1985

[Development of nonstenotic extracranial carotid plaques--a prospective study of its course with the Duplex system].

The natural history of a prospectively investigated group of patients with small non-stenotic extracranial carotid lesions (less than 30% lumen narrowing) was studied during 18 months. Using a specially designed high resolution (10 MHz) ultrasound Duplex system, 43 lesions were followed in 31 patients. Whereas the majority of the carotid atheromas remained unchanged (51%) or deteriorated (30%), spontaneous regression could be observed in 19%. Regression was limited to volume reduction of "soft plaques" and healing of "ulcerative" lesions, while "fibrous" and "hard plaques" remained unchanged or deteriorated. None of the patients developed cerebrovascular events during follow-up.

Adult↗