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Biomedical subjects

M Hennerici

Publications and source records attributed to M Hennerici.

At least 19 recordsLinked to original sources
PubMed2000

Temporal profile of release of interleukin-1beta in neurotrauma.

Timing and extent of trauma-induced release of interleukin-1beta (IL-1beta) in extracellular fluid of the CNS were analyzed. In brain tissue perfusates obtained by in vivo microdialysis a marked release of IL-1beta was unexpectedly detected within less than 60 min. At such an early stage of neurotrauma, mRNA expression of IL-1beta was detected whereas immunoreactivity for the IL-1beta protein was negative. Concentrations of extracellularly secreted IL-1beta protein gradually increased, peaked at day 2 and decreased thereafter. Drugs acting on mononuclear phagocytes significantly modulated IL-1beta secretion. This so far unrecognized acuity of IL-1beta release demonstrated here, may represent a precondition for the orchestrating role of this mediator in the cascade of inflammatory host response.

Animals↗
PubMed2000

Pulse-inversion contrast harmonic imaging: ultrasonographic assessment of cerebral perfusion.

Pulse-inversion contrast harmonic imaging is a new ultrasonographic technique that can assess brain perfusion. In an adult with moyamoya disease and multiple recurrent strokes, this method detected subtle hemispheric differences in temporal-lobe perfusion, presumably due to neovascularisation, which were not shown by xenon-computed tomography or magnetic resonance perfusion imaging.

Adult↗
PubMed2000

Reconstruction and visualization of irregularly sampled three- and four-dimensional ultrasound data for cerebrovascular applications.

Although recent studies have demonstrated the potential value of compounded data for improvement in signal-to-noise ratio and speckle contrast for three-dimensional (3-D) ultrasonography, clinical applications are lacking. We investigated the potential of six degrees-of-freedom (6-DOF) scanhead position and orientation measurement (POM) devices for registration of in vivo multiplanar, irregularly sampled ultrasound (US) images to a regular 3-D volume space. The results demonstrate that accurate spatial and temporal registration of four-dimensional (4-D) US data can be achieved using a 6-DOF scanhead tracking system. For reconstruction of arbitrary, irregularly sampled US data, we introduce a technique based upon a weighted, ellipsoid Gaussian convolution kernel. Volume renderings of 3-D and 4-D compounded in vivo US data are presented. The results, although restricted to the field of cerebrovascular disease, will be of value to other applications of 3-D sonography, particularly those in which compounding of data through irregular sampling may provide superior information on tissue or vessel structure.

Blood Flow Velocity↗
PubMed2000

Simultaneous assessment of brain tissue oxygenation and cerebral perfusion during orthostatic stress.

Simultaneous registration of cerebral tissue oxygenation parameters obtained by near infrared spectroscopy (NIRS), intracranial blood flow velocity (CBFV) measured by transcranial Doppler sonography (TCD) and basic cardiovascular parameters was carried out during a passive 80 degrees head-up tilt table test in 15 patients with a history of orthostatic syncope and 20 control subjects. In normals, the cardiovascular parameters showed a specific course after changing to a vertical position: the heart rate increased, the mean arterial blood pressure remained unchanged, and the CBFV decreased. The NIRS measurements showed an increase in deoxyhemoglobin (HHb) and a decline in oxyhemoglobin (O(2)Hb) and the regional oxygen saturation (RSAT). Patients had a significantly more prominent decline in arterial blood pressure (p < 0.001), CBFV (p < 0.001) and RSAT (p = 0.04). Five patients experienced symptoms of (pre)syncope during the experiment, which were associated with a further sudden and marked (>10%) drop of O(2)Hb. The results indicate that the combination of TCD and NIRS increases the understanding of hemodynamic and metabolic changes during orthostatic stress, which may lead to individually suited therapeutic procedures.

Blood Flow Velocity↗
PubMed1999

Inverse association between endogenous glucocorticoid secretion and L-selectin (CD62L) expression in trauma patients.

Exogenously administered glucocorticoids downregulate inflammatory host response, i.e. by inhibition of adhesion molecule expression on leukocyte surfaces. Here, possible associations between the trauma-induced endogenous secretion of cortisol and the expression of neutrophil adhesion molecules (L-selectin/CD62L, CD 11b, CD54) were studied in humans. Standardized elective hip arthroplasty was investigated as an exemplary condition of acute inflammation. In 20 patients, blood for quantification of cortisol and adrenocorticotropic hormone was obtained at minutes 10, 20, 30, 60, hours 1, 2, 4 and 10 and days 1,3 and 7. Expression of L-selectin/CD62L, CD11b and CD54 on neutrophil surfaces was determined preoperatively, and postoperatively at hours 1, 2, 3, 4, and 10 and at days 1 and 3. Secretion of both, adrenocorticotropic hormone and cortisol was significantly increased between 1-10 hours after onset of tissue injury. Compared to baseline values, CD11b expression was increased at hour 1 and normalized after day 1, whereas L-selectin/CD62L expression, mirroring this pattern was decreased until day 1. Patients with high endogenous glucocorticoid secretion exhibited significantly decreased expression selectively of L-selectin/CD62L. However, we also observed that glucocorticoids do not directly induce L-selectin shedding from neutrophil surfaces in vitro, arguing for more indirect glucocorticoid action on adhesion molecule expression. Together, this study showed that increased endogenous cortisol secretion is associated with lower expression of L-selectin on neutrophil surfaces in humans that is consistent with a downmodulating role of this neuroendocrine stress response in inflammatory leukocyte recruitment.

Adrenocorticotropic Hormone↗
PubMed1999

Interferon-gamma-inducing factor (IL-18) and interferon-gamma in inflammatory CNS diseases.

OBJECTIVE: To examine the intrathecal production of a newly identified cytokine, interferon-gamma-inducing factor (IL-18), together with interferon-gamma itself, in inflammatory diseases of the CNS (i.e., bacterial meningitis, viral meningoencephalitis, and MS). RESULTS: IL-18 concentrations in CSF were significantly increased in bacterial meningitis and tended toward increased levels in viral meningoencephalitis. In contrast, IL-18 was detectable only in a few patients with MS and healthy controls. Interestingly, interferon-gamma was significantly increased selectively in CSF of patients with viral meningoencephalitis. CONCLUSION: The observation of an intrathecal release of IL-18 in patients with meningitis argues for a pathophysiologic role of this novel cytokine in immunity against invading microorganisms the CNS.

Adult↗
PubMed1999

Vasoneuronal coupling in migraineurs after subcutaneous sumatriptan: a TCD study.

According to the trigeminovascular model of pain in migraine, sterile neurogenic inflammation of dural vessels stimulates nociceptive fibres of the trigeminal nerve. Sumatriptan, a 5-HT1 receptor agonist, blocks this reaction and mediates vasoconstriction of meningeal arteries. However, it is uncertain, whether sumatriptan also has a vasoconstrictive effect on cerebral arteries, which may influence vasoneuronal coupling and induce secondary cerebral blood flow changes. We studied changes of cerebral blood flow velocity (CBFV) and the pulsatility index (PI) in the posterior cerebral artery (PCA) after stimulus activation before, 10 min and 30 min after subcutaneous application of 6 mg sumatriptan, in order to assess potential vasoactive effects on cerebral circulation. CBFV was recorded from both PCAs simultaneously in 27 migraineurs (twenty women, seven men, mean age 29 years), and arterial blood pressure (BP), heart rate (HR) and respiration rate (RR) were monitored. Although the mean diastolic blood pressure rose significantly from 75 mm Hg to 81 mm Hg (P<0.05) and systolic blood pressure and respiration rates remained constant, average CBFV values remained constant. Similarly, the relative increase of CBFV by visual stimulation, which is clearly higher compared to controls in other studies (55.0% before, 52.6% after 10 min, and 52.4% after 30 min), and absolute mean values for CBFV and PI did not change after visual stimulation. These results provide evidence against the hypothesis that sumatriptan produces vasoconstriction in the intracranial human arterial circulation as a potential risk of cerebral ischemia.

Adult↗
PubMed1999

Arterial gas embolism after decompression: correlation with right-to-left shunting.

Paradoxical gas embolism is a possible cause of neurologic sequelae after decompression in divers. The authors detected arterial bubbles after decompression from chamber dives in two of six divers using transcranial Doppler sonography (TCD). Arterial bubbles correlated with the size of right-to-left shunting as diagnosed by contrast TCD. The pathway of spontaneous paradoxical embolism was tracked for the first time, supporting the concept of paradoxical gas embolism as a cause of early neurologic sequelae after decompression in at-risk divers.

Adult↗
PubMed1999

Fas (APO-1/CD95) in inflammatory CNS diseases: intrathecal release in bacterial meningitis.

Release of Fas (APO-1, CD95), a type L-membrane protein which plays a crucial role in cytokine-mediated apoptosis was investigated in bacterial meningitis, viral meningoencephalitis and multiple sclerosis in vivo. After correction for bloodbrain-CSF-disruption, significantly increased intrathecal release of Fas was demonstrated exclusively in bacterial meningitis arguing for an apoptotic cell death of granulocytes in the subarachnoidal space aimed to self-limit inflammatory host response.

Adolescent↗
PubMed1999

Modulation of striatal acetylcholine concentrations by NMDA and the competitive NMDA receptor-antagonist AP-5: an in vivo microdialysis study.

The effects of local perfusion with the competitive NMDA receptor antagonist 2-amino-5-phosphonovalerate (AP-5) and the glutamate receptor agonist N-methyl-D-aspartate (NMDA) on release of extracellular acetylcholine (ACh) and choline (Ch) in the dorsolateral striatum were studied using in vivo microdialysis in freely moving rats. AP-5 caused a dose-dependent decrease in ACh release that was counteracted by the addition of NMDA. Perfusion with AP-5 also decreased Ch levels. Local perfusion with NMDA induced an elevation of ACh release in low (10(-5) M), but not high (10(-2) M and 10(-3) M) concentrations, that were associated with massive cellular death. These inhibitory effects of AP-5 and the stimulatory effect of NMDA in non-neurotoxic dosages on ACh release provide further evidence for a tonic stimulation of striatal cholinergic interneurons by glutamatergic neurons via NMDA receptors.

2-Amino-5-phosphonovalerate↗
PubMed1999

Low-frequency, low-intensity ultrasound accelerates thrombolysis through the skull.

Systemic thrombolysis of acute ischemic stroke with recombinant tissue plasminogen activator (rt-PA) has been established recently. Whereas the delay to and the rate of vessel recanalization are unknown, they are likely slower and smaller than for local application of rt-PA. This may contribute to the small benefits of recovery reported and stimulate further investigations to improve clot lysis. Pilot studies indicate that continuous-wave low-frequency ultrasound (US) can accelerate rt-PA-mediated recanalization of peripheral thrombotic vessel occlusion. For the hypothesized therapeutical purpose in stroke treatment, we measured the attenuation of ultrasound through the skull at different frequencies and intensities (33.3 and 71.4 kHz; 0.5 and 3.4 W/cm2), and investigated thrombolysis in vitro (n = 125 clots). Attenuation was lowest by transtemporal insonation of 33.3 kHz, 0.1 dB (0.9). Thrombolysis (artificial fibrin-rich clots) was significantly increased after 1 h (p < 0.025) and after 3 h (p < 0.01) for US treatment in combination with rt-PA vs. rt-PA alone. Results suggest that US increases rt-PA-mediated thrombolysis through the skull and may improve benefits of thrombolytic stroke treatment in vivo.

Brain Ischemia↗
PubMed1999

Comparison of transcranial Doppler flow velocity and cerebral blood flow during focal ischemia in rabbits.

The predictive value of transcranial Doppler (TCD) cerebral blood flow velocity (CBFV) measurements for cerebral blood flow (CBF) calculations in humans is still controversial, and experimental correlative studies are lacking. The aim of the present study was to validate TCD signals of CBFV during focal cerebral ischemia. Therefore, CBFV determined in the middle cerebral artery (MCA) was compared with values of CBF obtained from autoradiograms of ischemic brain areas. To determine CBFV, a transcranial Doppler ultrasound probe (TCD) adapted to small sample volumes was used in 9 rabbits. CBF was quantified after a final infusion of [14C]-iodoantipyrine in the same animals. For focal cerebral ischemia induction, two threads were flushed upward simultaneously into the internal carotid artery, resulting in a flow reduction in the ipsilateral MCA. After thread occlusion, mean systolic CBFV in the MCA decreased from 49 +/- 9 cm/s to 22 +/- 3 cm/s. CBF in the caudate nucleus was reduced (19 +/- 8 mL/100 g/min) compared to the contralateral nonischemic side (52 +/- 18 mL/100 g/min). The decrease in hemispheric CBF correlated well with the decrease in both mean systolic (r = 0.97) and diastolic (r = 0.94) CBFV in the MCA (p < 0.01). The decrease in CBFV determined by transcranial Doppler ultrasound in the MCA appears to reflect the reduction in CBF in the affected brain hemisphere and can be used as a quantitative in vivo parameter for tissue perfusion.

Animals↗
PubMed1999

Clinical range and MRI in Creutzfeldt-Jakob disease with heterozygosity at codon 129 and prion protein type 2.

A 68 year old woman with sporadic Creutzfeldt-Jakob disease is described, who neither showed characteristic EEG abnormalities nor a positive test of the neuronal protein 14-3-3 or neuron specific enolase (NSE) in CSF, despite a clinical presentation with ataxia of cerebellar type, rapidly progressive dementia, myoclonus, and marked hyperintense signal abnormalities in the deep cortical layers and the basal ganglia on T2 and diffusion weighted MRI. Moreover she showed atypical clinical features with a syndrome of inappropriate antidiuretic hormone (ADH) secretion (SIADH) and a peripheral sensorimotor polyneuropathy. Whether these disturbances are independent of Creutzfeldt-Jakob disease or a feature of it is discussed. It has recently been shown that in Creutzfeldt-Jakob disease different clinical and pathological phenotypes correlate with the polymorphism at codon 129 of the prion protein gene (PRNP) and the type of the protease resistant fragment that accumulates in the brain. According to the new classification at least six sporadic variants of Creutzfeldt-Jakob disease exist. The molecular genetic analysis showed heterozygosity of PRNP at codon 129 for methionine and valine and the presence of PrP(CJD) type 2 in the brain of this patient. As a new feature of changes on MRI, striking cortical changes of hyperintense signals are described in diffusion weighted as well as T2 weighted MRI that directly correlate with the histomorphological spongy degeneration of the brain in this region. In cases of rapidly progressive dementia, Creutzfeldt-Jakob disease always needs to be considered even if unusual features are present and current diagnostic criteria are not in favour of this disease.

Aged↗