Biomedical subjects

A Hamberger

Publications and source records attributed to A Hamberger.

At least 37 records · Page 2Linked to original sources

PubMed1997

In situ detection of myocardial infarction in pig by measurements of aspartate aminotransferase (ASAT) activity in the interstitial fluid.

Microdialysis probes permeable to large molecules (m.w. cut-off > 200 kD) were introduced into the myocardium of anaesthetized pigs in order to evaluate their potential for early detection of myocardial ischaemia and enzyme markers for infarction. The left anterior descending coronary artery was occluded for 30 min and the myocardium was reperfused for 3 h. The concentrations of aspartate aminotransferase (ASAT), lactate, glucose and selected free amino acids were measured. The levels in the interstitium of ischaemic and non-ischaemic myocardium were compared with those in plasma from the coronary sinus as well as from a peripheral vein. Twelve probes were inserted in six pigs and withdrawn after 8-72 hours of sampling. No complications occurred. Simultaneous 100% increase of ASAT and lactate was found in myocardial dialysates after 30 min of ischaemia. ASAT activity remained at that level until the end of reperfusion. The plasma peak ASAT level was not attained until after 3 h. Glutamate was the only amino acid which increased significantly in the myocardial interstitium during ischaemia, peaking after 30 min of reperfusion. Dialysates from the unaffected myocardium showed no effects on lactate, ASAT or glutamate. The use of myocardial microdialysis for pre- and postoperative recordings in man is discussed.

Amino Acids↗

PubMed1996

Presence of S-100 beta in cholinergic neurones of the rat hindbrain.

The double staining of S-100 beta and choline acetyltransferase (ChAT) revealed that S-100 beta immunoreactivity was localized in most, but not in all, cholinergic neurones in the somatomotor nuclei of the cranial nerves and in the ambiguus nucleus. S-100 beta was present in almost all cholinergic neurones in the brain stem reticular, red, vestibular (excluding medial), mesencephalic trigeminal and cerebellar nuclei. However, S-100 beta immunoreactivity was lacking in cholinergic neurones in the parabrachial complex, the dorsal motor nucleus of the vagal nerve and most sensory nuclei. No S-100 beta-positive neurones lacked ChAT immunoreactivity. Taken together with the fact that the vulnerability of motoneurones to axotomy is markedly reduced in the first 3 postnatal weeks, during which period neuronal S-100 beta appears and increases, a possible effect of S-100 beta on the survival of cholinergic motoneurones may be suggested.

Animals↗

PubMed1996

Appearance of neuronal S-100 beta during development of the rat brain.

In addition to being an astroglial protein, S-100 beta is localised in distinct populations of neurons in the adult rat hindbrain. We report, here, the expression of S-100 beta in both neurons and glia of the rat brain during development. Prenatally, S-100 beta immunoreactivity was confined to glial cells close to the germinal zone. After birth, S-100 beta positive glial cells were seen mainly in the brainstem and cerebellum, while only a few were detected in cerebral cortex and hippocampus. The number of S-100 beta containing glial cells increased steadily during the first 2 postnatal weeks after which the adult pattern was attained. No S-100 beta containing neurons were present prenatally. The first S-100 beta containing neurons were seen in the mesencephalic trigeminal nucleus at postnatal day 1 (P1), and in the motor trigeminal nucleus at P3. Neuronal S-100 beta immunoreactivity in other nuclei was mostly attained from the 10th to the 21st postnatal day. The neuronal S-100 beta immunoreactivity was first detected in the cell nuclei during development, then increased in the cytoplasm with ages. A nuclear staining in many immunoreactive neurons persisted until the adult. It usually took 1 to 2 weeks for neuronal S-100 beta to attain the adult staining pattern, i.e., heavy staining of the cytoplasm and processes, after its appearance. The forebrain never contained S-100 beta positive neurons. The S-100 beta is first expressed in glial cells, suggesting it is primarily of the glial origin. Coupled with neurotrophic effects of the protein, the time course of neuronal S-100 beta expression during the critical period of neuronal development implies that it may be involved in neuronal differentiation and maturation.

Animals↗

PubMed1996

[Arthroscopic replacement of the anterior cruciate ligament with a double semitendinosus tendon].

At the university hospital of emergency surgery in Innsburck and at the emergency services department of the hospital in Schwaz, anterior cruciate ligament reconstruction was performed in 467 patients between January 1992 and September 1993. In 117 cases, a double semitendinous tendon was used as an autograft. A total of 60 of these patients were followed up at an average of 20 months (13-33) after reconstruction. The results were rated according to the OAK and the Tegner scores. Objective measurements of instability were carried out by a KT 1000 arthrometer. In addition, 21 patients underwent computer-interfaced dynamometer testing using a Cybex 6000. Standardized loading of the thigh muscles was performed at angular velocities of 60 degrees/s (3 repetitions) and 240 degrees/s (30 repetitions): peak torques and total work were analyzed. The mean age was 23.5 years (17-55): 48 were male, 21 female. The main reasons for the ACL ruptures were sports injuries (51 cases). The patients were classified into three groups according to the data of the repair (group 1 reconstruction up to 1 week after trauma-28 patients: group 2: reconstruction between the 2nd and 6th week after trauma-15 patients: group 3: reconstruction 6 and more weeks after trauma-26 patients). In group 1. additional ruptures of the menisci. lesions of the MCL. and chondromalacia were seen in 71.4%. in group 2 in 73.3% and in group 3 in 80.8%. The average rating in the OAK score was 90.16 points: 38 patients (55.70%) had excellent results. 18(26.09%) were good. 9(13.04%) were fair and 4(5.80%) were poor. The Tegner activity score showed a reduction of 0.36 points on average. The largest amount of anterior translation was performed with the KT 1000 manual drawer test (2.29 mm on average compared with the contralateral side). Dynamometer testing showed a statistically significant difference in flexor and extensor mechanism (compared with the non-involved side) in both peak torques and total work. A repeat arthroscopy became necessary in five cases: arthrofibrosis in three and incipient joint infection in two cases.

Adolescent↗

PubMed1996

Plasticity of granule cell-mossy fiber system following kainic acid induced seizures: an immunocytochemical study on neurofilament proteins.

Abnormal reestablishment of mossy fibers with the CA3 pyramidal cells and granule cells is an important aspect of postlesional plasticity in epilepsy. However, basis for the structural reorganisation and functional consequences of the event remain uncertain. Therefore we have investigated alterations of neurofilaments, major cytoskeletal components of neurons, in the rat hippocampus after the kainic acid (KA) administration, an experimental model for the temporal lobe epilepsy. The immunoreactivity for phosphorylated heavy weight neurofilament (pNFH) and non-phosphorylated heavy weight neurofilament (npNFH), in particular the pNFH, decreased in the CA1 field and inner molecular layer of the dentate gyrus during 3 and 10 days after the KA administration. After 10 days, npNFH immunoreactivity appeared in the mossy fibers, in which it is normally absent, meanwhile the pNFH staining in the mossy fibers did not decrease. From day 21, the immunoreactivity of pNFH and npNFH was normal or above normal in the CA1 stratum lacunosum-moleculare, mossy fibers, hilus and inner molecular layer of the dentate gyrus. These alterations in the later phase remained at least to day 90. The reappearance and increase of the neurofilament immunoreactivity in the inner molecular layer of the dentate gyrus probably reflects a collateral extension of the granule cell axons known as mossy fiber sprouting. The results suggest that neurofilament changes in the granule cell-mossy fiber system may be a morphological basis for the structural reconstruction of granule cell axons, and neurofilaments are involved in the plasticity after the KA induced seizures.

Animals↗

PubMed1996

High levels of glycine and serine as a cause of the seizure symptoms of cavernous angiomas?

Cavernous angiomas are vascular malformations that cause neurodegeneration and symptoms including epileptiform seizures, headache, and motor deficits. Following neurosurgical removal of the angiomas, patients mostly recover well and become seizure-free. This study reports on the levels of certain amino acids in angiomas, obtained from 13 patients. Distinct zones of the angiomas were analyzed, from the thrombotic core, via gliotic, hemosiderin-infiltrated intermediate zones, to a periphery without macroscopic abnormalities. The neurotransmitter amino acids glutamate, aspartate, and GABA as well as phosphoethanolamine displayed decreasing levels from the periphery to the core, reflecting the gradual neuronal loss. Compared with normal brain tissue, there was a marked increase in the levels of serine (fivefold), glycine (10-fold), and ethanolamine (20-fold) in the peripheral zone of the cavernous angiomas. The results are discussed in relation to seizures and NMDA receptor activation, neuron-glia interactions, membrane phospholipids, and blood-brain barrier function.

Adult↗

PubMed1995

S-100 beta has a neuronal localisation in the rat hindbrain revealed by an antigen retrieval method.

The localisation of S-100 in mammalian CNS neurons has been under debate for more than two decades. We address the question with two polyclonal and two new monoclonal antibodies. The specificity and the distribution in rat brain is based on an antigen retrieval method. We present evidence that aldehyde fixatives mask S-100 beta in neurons, and that the immunoreactivity is retrieved after trypsinisation. Neuronal S-100 beta is also detected in unfixed and ethanol fixed sections. The neuronal immunoreactivity is partly solubilised from unfixed tissue sections with 2.5 mM EDTA and is completely extracted with 2.5 mM EDTA and 1% Triton X-100. Most of the glial S-100 beta is washed out from unfixed tissue sections with saline. S-100 beta has distinct distribution in neurons of the hindbrain, i.e., the brainstem and cerebellum, but is not observed in the forebrain. One of the monoclonal antibodies immunostained neither neurons nor glia when it had been absorbed with S-100 crosslinked to nitrocellulose membranes. The distribution of neuronal S-100 beta differed from that of other neuronal calcium binding proteins, such as calbindin and parvalbumin. It was confined mainly to cholinergic neurons of the hindbrain. The presence of S-100 beta in distinct neuronal populations may indicate neurotrophic effects of S-100 beta. The notion is supported by the capability of S-100 to cause neurite outgrowth in vitro.

Animals↗

PubMed1995

S-100 beta immunoreactivity in neurones of the rat peripheral sensory ganglia.

S-100 beta, which is capable of exerting neurotrophic effects on cultured neurones and promoting the survival of motor neurones in vivo, has recently been found in distinct neurones of the rat hindbrain. Here we report that S-100 beta, as well as being present in satellite and Schwann cells, is also present in neurones of sensory ganglia (dorsal root ganglion, trigeminal, petrosal, jugular and nodose ganglia) but absent from neurones of the superior cervical ganglion. In the sensory ganglia, many neurones were immunoreactive, while the staining intensity varied among the neurones. Neuronal S-100 beta appeared in developing rats as early as postnatal day 1. No immunoreactive neurones were observed in the superior cervical ganglion during development. The results are suggestive of selective neurotrophic effects of S-100 beta.

Animals↗

PubMed1995

Expression of Ca(2+)-ion permeable alpha-amino-3-hydroxy-5-methyl-4-isoxazolepropionate (AMPA) receptors in Xenopus oocytes injected with total RNA from human epileptic temporal lobe.

By using the Xenopus oocyte as an expression system, we have performed a series of experiments in order to examine the divalent cation-permeability of alpha-amino-3-hydroxy-5-methyl-4-isoxazolepropionate (AMPA) receptors from the human epileptic temporal lobe. Xenopus oocytes, injected with total RNA from the epileptic temporal lobe, were tested for expression of receptors by a conventional two electrode voltage-clamp technique. Administration of glutamate and AMPA gave small or no clear current responses, whereas kainate produced large inward non-desensitizing currents. The current responses evoked by kainate were concentration dependent. Experimental data gave a Hill coefficient of 1.06 and an EC50 value of 87 microM. The current to voltage relationship showed an inward rectification and when the concentration of divalent cations were enhanced, there was a shift in the reversal potential from -11 mV (2 mM Ca2+) to 12 mV (60 mM Ba2+). This yielded a pBa2+/pK+ permeability ratio of 1.6 when the constant field equation was used. The amplitude of the currents evoked by 600 microM kainate in solutions containing higher Ba(2+)-ion concentrations was markedly diminished (46% in 10 mM Ba(2+)- and 75% in 60 mM Ba(2+)-solution), when compared to those obtained in normal Ringer's solution, suggesting interactions between different cation species and/or screening of surface charges.

Animals↗

PubMed1995

Accuracy of field alignment in radiotherapy of head and neck cancer utilizing individualized face mask immobilization: a retrospective analysis of clinical practice.

Deviations between simulation and first check films were quantitatively assessed for 95 unselected head and neck cancer patients. All measured deviations--calculated on the basis of a total of 190 simulation and 380 verification films--were normally distributed, with mean values of 0-3 mm and standard deviations of 3-5 mm. Of the absolute deviations, 50% and 95% were within 3 mm and 9 mm, respectively. These results should be considered in clinical practice when prescribing safety margins and adequate cut off doses for sparing critical organs in head and neck cancer.

Head and Neck Neoplasms↗

PubMed1995

Phosphorylated and non-phosphorylated neurofilament proteins: distribution in the rat hippocampus and early changes after kainic acid induced seizures.

The regional distribution of neurofilament proteins in the rat hippocampus and their early changes after kainic acid induced seizures were investigated immunocytochemically with antibodies against light weight neurofilament, phosphorylated and non-phosphorylated heavy weight neurofilament. The light weight and non-phosphorylated heavy weight neurofilaments were distributed more unevenly than the phosphorylated neurofilament. The perikarya and processes of pyramidal cells in the CA3 field contained the highest light weight and non-phosphorylated heavy weight neurofilaments, while the perikarya of granule cells contained only few light weight neurofilament and the perikarya of CA1 pyramidal cells were even devoid of immunoreactivity of both light and heavy weight neurofilaments. The fiber staining of the light weight and non-phosphorylated heavy weight neurofilaments, especially the former, was less in the CA1 field and molecular layer of dentate gyrus. The phosphorylated neurofilament immunoreactivity was identified only in axons. Mossy fibers, the axons of granule cells, contained the light weight and phosphorylated heavy weight neurofilaments, but not the non-phosphorylated neurofilament. Seven days after the kainic acid induced seizures, the phosphorylated neurofilament staining was greatly reduced in the CA1 and inner molecular layer of the dentate gyrus, probably resulting from the axonal degeneration of the Schaffer collaterals and the commissural/associational fibers. Furthermore, the nonphosphorylated neurofilament appeared in the mossy fibers of the CA3 stratum lucidum, which normally do not express such immunoreactivity. The results indicate that the neurofilaments are altered following the neuronal degeneration and postlesional plasticity caused by the kainic acid administration. Therefore, the examination of various phosphorylated neurofilaments may offer a comprehensive understanding of major hippocampal pathways, axonal plasticity and the possible roles of neurofilaments in the hippocampus following excitotoxic insults.

Animals↗

PubMed1995

Effects of vagus nerve stimulation on amino acids and other metabolites in the CSF of patients with partial seizures.

Electrical stimulation of the vagus nerve (VNS) is a new method for the treatment of patients with medically intractable epilepsy. Sixteen patients, ten of whom participated in a larger multicenter double-blind trial on the efficacy of VNS in epilepsy, and six who participated in pilot studies, consented to participate in the present study. Ten patients received HIGH stimulation and six patients LOW stimulation for the 3-month trial. Cerebrospinal fluid (CSF) samples (16 ml) were collected both before and after 3 months of VNS. Amino acid and neurotransmitter metabolites were analyzed. Four patients responded to VS with more than a 25% seizure reduction after 3 months. Mean and median concentrations of phosphoethanolamine (PEA) increased in responders and decreased in nonresponders. Free GABA increased in both groups but more so in the nonresponders. After 9 months of VS (6-9 months on HIGH stimulation) 4 of 15 patients had more than 40% seizure reduction. There were significant correlations between seizure reduction and increases in asparagine, phenylalanine, PEA, alanine and tryptophan concentrations. Comparison between patients with HIGH or LOW stimulation showed a significant increase in ethanolamine (EA) in the HIGH group and a decrease in glutamine in the LOW group. All patients regardless of response or stimulation intensity showed significantly increased total and free GABA levels. A decrease in CSF aspartate was marginally significant. Other trends were decreases in glutamate and increases in 5-hydroxyindoleacetic acid. Chronic VNS appears to have an effect on various amino acids pools in the brain.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗

PubMed1995

Seizure frequency and CSF parameters in a double-blind placebo controlled trial of gabapentin in patients with intractable complex partial seizures.

Gabapentin (GBP) is a non-protein-bound gamma amino acid which is not subjected to metabolic degradation in man. As part of a placebo-controlled double-blind study, patients suffering from intractable complex partial seizures with or without secondary generalization were followed with lumbar punctures at baseline and after three months of GBP treatment (900 mg/day or 1200 mg/day). Cerebrospinal fluid (CSF) was analyzed for concentrations of GBP, amino acids including GABA, homovanillic acid (HVA), and 5 hydroxyindoleacetic acid (5-HIAA). The results indicate that there were no changes in the selected amino acids, HVA, or 5-HIAA after GBP treatment. At steady state the CSF/plasma ratios of GBP ranged from 0.056 to 0.34, indicating that there may be some type of active out-transport of GBP across the blood-brain barrier. No linear relationship was observed between plasma and CSF levels in these patients.

Acetates↗

PubMed1995

Intracerebral dialysis and the blood-brain barrier.

The aim of the study was to evaluate how implantation of a dialysis probe influences the blood-brain barrier. Leakage of endogenous serum albumin was evaluated by Evans blue/albumin staining and by immunohistochemistry. The passage from blood to dialysate of two substances that normally do not pass into the brain, [3H]-inulin and glutamate, was studied 3 and 24 h after insertion of a dialysis probe. Evans blue, given 20 min before rats were killed, was observed around the probe and surrounding brain tissue. Albumin immunoreactivity was seen at considerable distance from the probe with larger spread at 24 h than at 3 h after probe insertion. Glutamate and [3H]inulin were detected in the dialysate with no significant further increase of radioactivity after intracarotid infusion of protamine sulfate that enhances the permeability over the blood-brain barrier. When protamine was followed by infusion of glutamate, the concentrations of taurine increased in the dialysate in four of eight rats. That plasma constituents have access to the brain around the dialysis probe is essential to consider, particularly in studies using substances and drugs that do not pass an intact blood-brain barrier.

Animals↗

PubMed1995

Effects of prostaglandin E2 and capsaicin on behavior and cerebrospinal fluid amino acid concentrations of unanesthetized rats: a microdialysis study.

Prostaglandin E2 (PGE2) delivered to the spinal cord produces an increased sensitivity to noxious (hyperalgesia) and innocuous (allodynia) stimuli. The mechanisms that underlie this effect remain unknown, but a PGE2-evoked enhancement of spinal neurotransmitter release may be involved. To address this hypothesis, we examined the effect of PGE2 on CSF concentrations of amino acids and also the modulatory effect of PGE2 on capsaicin-evoked changes of spinal amino acid concentrations using a microdialysis probe placed in the lumbar subarachnoid space. Amino acids were quantified using HPLC with fluorescence detection. Addition of 1 mM, but not 10 or 100 microM, PGE2 to the perfusate for a 10-min period (flow rate, 5 microliters/min) evoked an immediate increase (80-100%) in glutamate (Glu), aspartate (Asp), taurine (Tau), glycine (Gly), and gamma-aminobutyric acid (GABA) concentrations. Similarly, capsaicin infusion (0.1-10 microM) induced a dose-dependent increase in Glu, Asp, Tau, Gly, GABA, and ethanolamine levels. Significant increases in amino acid levels evoked by PGE2 or capsaicin were associated with a touch-evoked allodynia. The combination of PGE2 (10 microM) and capsaicin (0.1 or 1.0 microM) at concentrations that individually had no effect together evoked a significant increase (60-100%) in Glu, Asp, Tau, Gly, and GABA concentrations and produced tactile allodynia. These data demonstrate that spinally delivered PGE2 or capsaicin substantially elevates CSF concentrations of both excitatory and inhibitory amino acids. The capacity of PGE2 to enhance and prolong capsaicin-evoked amino acid concentrations may be one of the mechanisms by which spinal PGE2 produces hyperalgesia and allodynia.

Amino Acids↗

PubMed1995

The neuronal environment after subarachnoid haemorrhage--correlation of amino acid and nucleoside levels with post-operative recovery.

The study explores biochemically the neuronal environment adjacent to a subarachnoid haemorrhage in 11 patients after neurosurgical clipping of an arterial aneurysm. Extracellular fluid (ECF) from the rectus gyrus and subarachnoid fluid (SAF) were sampled with microdialysis probes. The concentrations of amino acids and nucleosides were monitored in 60 min samples collected over 2-4 days. The patients were 33-67 years of age. Surgery was performed 0-5 days after rupture of the aneurysm in 8 patients. One patient was operated on after 15 months. Clipping of aneurysms without prior haemorrhage was performed in two cases. Markedly elevated concentrations of the excitatory amino acid glutamate was observed in the ECF of only one patient who underwent surgery within 8 hours after the haemorrhage. Moderate glutamate elevations were seen in two patients and of aspartate in another patient. Five patients displayed periods of varying length of specifically elevated taurine concentrations in ECF or SAF. Transient periods of high concentrations of glycine and serine were seen in two patients. Even though average concentrations of all amino acids were fairly similar in the ECF and SAF, the pattern of changes vs. time differed markedly in the two compartments. Presently, we conclude that the level of consciousness in the post-operative phase was inversely related to total amino acid concentration in the ECF. Furthermore, while the ECF concentrations of taurine and glycine increased both specifically and transiently in several patients, excitatory amino acid levels were not appreciably elevated subsequent to the neurosurgical intervention.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗

PubMed1994

Amino acids in extracellular fluid in vasogenic brain edema.

We have investigated if changes in brain dialysate, reflecting alterations in brain extracellular composition, can be detected during the development of vasogenic brain edema. The blood-brain barrier was opened by intracarotid infusion of 5 or 10 mg protamine sulphate. The rats were killed two hours after opening of the BBB when the brains were macroscopically edematous, after 10 mg but not 5 mg protamine sulphate. No significant alterations in the amino acid concentration in the dialysate were observed after the lower dose. 40 min after infusion of 10 mg protamine, the level of glutamate was significantly increased in the dialysate followed by that of aspartate, glycine, phosphoethanolamine and taurine 10 min later and a further delayed increase in GABA. We conclude that the development of vasogenic brain edema is associated with significant increases in extracellular concentration of excitatory amino acids, of taurine, and of phosphoethanolamine and GABA.

Amino Acids↗

PubMed1994

Concentrations of amino acids in extracellular fluid after opening of the blood-brain barrier by intracarotid infusion of protamine sulfate.

This article evaluates the influence of an opening of the blood-brain barrier (BBB) on compounds in brain extracellular fluid. The concentrations of amino acids and some other primary amines were determined in dialysates sampled from the right parietal cortex of rats before and after an intracarotid infusion of protamine sulfate. Extravasated plasma proteins were visualized by Evans blue/albumin and immunohistochemistry. CSF albumin--an indicator of blood-CSF barrier opening--was quantified with immunoelectrophoresis. The brains were macroscopically edematous after 10 mg but not after 5 mg of protamine sulfate. The higher dose led to a 50% death rate. The concentrations of amino acids did not change 10 min after the BBB opening. No significant alterations in the amino acid concentrations were observed after the lower dose. The concentrations of glutamate, aspartate, GABA, glycine, taurine, and phosphoethanolamine increased significantly within 50-80 min after the infusion of 10 mg of protamine sulfate. CSF albumin levels were significantly increased 1 h after infusion. We conclude that a dysfunction of the BBB, of a degree known to induce brain edema (10 mg of protamine sulfate), significantly increases the extracellular concentration of excitatory amino acids, GABA, taurine, and phosphoethanolamine in the extracellular space.

Amino Acids↗