Cross-sectional area of the ulnar nerve after decompression at the cubital tunnel

A total of 48 patients undergoing surgical decompression of the ulnar nerve at the cubital tunnel between February 2010 and May 2013 were retrospectively studied to determine changes in the cross-sectional area of the nerve by the technique of neurosonography. The mean follow-up was 46 months. Post-operative follow-up examination of the cross-sectional area of the ulnar nerve showed a slight reduction in the mean value from 13.8 mm(2) (pre-operative) to 12.9 mm(2) (post-operative). Of the 48 patients, 36 showed a reduction in the cross-sectional area. No correlation was detected between the clinical and sonographic outcomes. Ultrasound seems to be of limited value in the post-operative assessment of patients with entrapment neuropathy of the ulnar nerve.

LEVEL OF EVIDENCE

IV.

The importance of genetic susceptibility in Dupuytren's disease

Dupuytren's disease (DD) is a progressive fibromatosis that causes the formation of nodules and cords in the palmar aponeurosis leading to flexion contracture of affected fingers. The etiopathogenesis is multifactorial with a strong genetic predisposition. It is the most frequent genetic disorder of connective tissues. We have collected clinical data from 736 unrelated individuals with DD who underwent surgical treatment from Germany and Switzerland. We evaluated a standardised questionnaire, assessed the importance of different risk factors and compared subgroups with and without positive family history. We found that family history clearly had the strongest influence on the age at first surgery compared to environmental factors, followed by male sex. Participants with a positive family history were on average 55.9 years of age at the first surgical intervention, 5.2 years younger than probands without known family history (p = 6.7 × 10(-8) ). The percentage of familial cases decreased with age of onset from 55% in the 40-49 years old to 17% at age 80 years or older. Further risk factors analysed were cigarettes, alcohol, diabetes, hypertension, and epilepsy. Our data pinpoint the importance of genetic susceptibility for DD, which has long been underestimated.

Liver fibrosis staging with contrast-enhanced ultrasonography: prospective multicenter study compared with METAVIR scoring

We prospectively assessed contrast-enhanced sonography for evaluating the degree of liver fibrosis as diagnosed via biopsy in 99 patients. The transit time of microbubbles between the portal and hepatic veins was calculated from the difference between the arrival time of the microbubbles in each vein. Liver biopsy was obtained for each patient within 6 months of the contrast-enhanced sonography. Histological fibrosis was categorized into two classes: (1) no or moderate fibrosis (F0, F1, and F2 according to the METAVIR staging) or (2) severe fibrosis (F3 and F4). At a cutoff of 13 s for the transit time, the diagnosis of severe fibrosis was made with a specificity of 78.57%, a sensitivity of 78.95%, a positive predictive value of 78.33%, a negative predictive value of 83.33%, and a performance accuracy of 78.79%. Therefore, contrast-enhanced ultrasound can help with differentiation between moderate and severe fibrosis.

Dimensions multiples de la fatigue d’origine neurologique : différences entre l’accident vasculaire cérébral et la sclérose en plaques

INTRODUCTION

Fatigue is a complex, subjective experience, frequent in multiple sclerosis (MS) and stroke patients. The tiredness these patients experience can take on many features depending not only on the cerebral location of the lesions and mood aspects, but also on the pathophysiology of the disease. Thus, it is reasonable to expect that fatigue may have different implications in MS and stroke. The aim of the present work was to compare fatigue syndrome in these two populations. Patients were matched for handicap.

MATERIALS AND METHODS

Seventy-nine stroke and 39 MS outpatients were included with the following inclusion criteria: i) patients with possible or relapsing-remitting MS with an Expanded Disability Status Scale (EDSS) score<2.5, disease duration<6 years, and stable medical condition for at least 6 weeks; ii) stroke patients with mild neurological impairment, i.e. scoring<3 at the National Institute of Health Stroke Scale (NIHSS) one year after stroke; iii) absence of functional impairment (Barthel index=100) and similar negligible handicap (Rankin scale<2 for both groups); no or mild cognitive deficit; iv) neither DSMIV criteria of depression, nor significant anxious/depressive symptoms (Hospital Anxiety and Depression scale; HAD; score<8) in both groups. The Fatigue Assessing Instrument (FAI) was used to assess fatigue.

RESULTS

Twenty-nine percent of stroke and 46 p. cent of MS patients had a significant score on the FAI (p<0.05). Multiple regression analysis using groups, gender and age as factors showed a group effect in 3 out of 4 subscales: MS patients scored higher than stroke patients mainly for psychic impact (4.86 vs. 3.28), but also for severity (mean 3.86 vs. 2.97) and specificity (4.36 vs. 3.32). Response to rest (5.36 vs. 6.06) only tended to be better in the stroke group. In the subpopulation with significant fatigue scores, psychic impact was more elevated in the MS group. The functional consequence of fatigue in physical, professional and social activities were similar.

DISCUSSION

Fatigue was more severe in MS than stroke patients, independently of disability. The most significant factor in the MS group was the psychic impact, reflecting impaired motivation, concentration and irritability, despite the absence of depression. However, subjective consequences of fatigue on work, family and leisure activities were comparable in both groups.

Intentional motor phantom limb syndrome

OBJECTIVE

To investigate the clinical and anatomic correlates of a previously unreported form of chronic supernumerary phantom limb, which developed only in association with motor intent directed at a hemiplegic-anesthetic upper limb.

METHODS

We explored the phenomenology of the phantom illusion in the light of motor control models. Hemodynamic correlates of supernumerary phantom limb were studied with an fMRI sensorimotor paradigm consisting of finger-thumb opposition movements.

RESULTS

The kinesthetic-proprioceptive illusion of a third arm was triggered by any attempt to move the paretic limb, by bimanual actions, and by motor imagery involving the nonfunctional limb. The responsible lesion destroyed the posterior part of the posterior limb of the internal capsule on the opposite side, damaging corticospinal and thalamocortical tracts. Comparison between fMRI signals performed during virtual movement of the phantom hand vs imaginary movement of the paretic hand showed increased activation in thalamus and caudate nucleus in the first condition.

CONCLUSIONS

A preserved sense of agency provided by intact premotor processes translating intention into action may lead to the vivid feeling of movement in a paralyzed limb, similar to kinesthetic illusions in amputees. The interruption of thalamic afferences may explain the persistence and stability of the phantom by preventing any correction of the mismatch between expected and effective movement. The increased blood oxygen level-dependent (BOLD) signal in the basal ganglia-thalamus-cortex pathway during movement of the supernumerary hand may reflect an abnormal closed-loop functioning of the thalamocortical system underlying the phantom phenomenon.

[The iatrogenic carpal tunnel syndrome--case report]

An inadequate indication for a carpal tunnel revision procedure may be followed by disastrous sequelae for the patient. So it may be justified to talk of iatrogenic CTS. A patient suffering from bilateral CTS is presented who had been operated on six times in all. The following techniques had been used by an orthopedic surgeon, a neurologist, a neurosurgeon and a hand surgeon: microsurgical neurolysis, epineurectomy, neuroma resection, tenosynovectomy and finally a hypothenar fat flap. Initial cause for this fatal series was scar tenderness following lesion of the muscular and palmar branches of the median nerve in the first or second operation. Since sensory nerve conduction was normal after decompression had been performed, there would have been no indication for further surgery of the median nerve. Resection of the neuromas of the two injured branches was not followed by any relief for the patient nor did wrapping the nerve in a fat flap help. Such courses may lead to high costs in health care and occupational disability. They can be avoided by competent neurological and electrophysiological examination, correct interpretation of findings as well as critical consideration of the indication for revision procedures.

Rezidiv- und Korrektureingriffe beim Karpaltunnelsyndrom

BACKGROUND

With an increasing number of operative procedures for CTS, the number of reoperations is increasing too. These procedures are not in general performed because of recurrence, other reasons may play a role for the failure of the initial operation or recurrent symptoms. METHODS AND CLINICAL MATERIAL: Revision procedures performed in 57 patients in the practice for peripheral neurosurgery from January to September 2004 were analyzed for incision, intraoperative findings, method of operation, electrophysiological findings, and revised diagnosis. Moreover, the data were compared with 185 revision procedures performed in the years from 1986 up to 1994.

RESULTS

2.4 % of all CTS operations were revision procedures (in the former time period 1.5 %). In 59 % of revision operations (former 50 %) an incomplete release of the transverse ligament was found, in 27 % (former 31 %) typical recurrence, in 5 % (former 6 %) nerve lesions, and in 9 % (former 13 %) no abnormalities so that other reasons for complaints of mainly radicular lesions must be assumed. In cases of incomplete release of the transverse ligament, only in 16 % of the patients were normal skin incisions seen, but in 56.3 % there were small incisions (i.e., short or mini-incisions). Typical CTS recurrence occurred mainly in hemodialysis patients, nerve lesions were seen mainly when endoscopic procedures were performed.

CONCLUSION

Diagnostic problems because of incomplete or misinterpreted ENG findings may lead to delayed or useless primary as well as revision operations. Too small incisions but also endoscopic procedures used by less experienced surgeons are accompanied with an increased risk for avoidable revisions and nerve lesions. Not only for forensic reasons but also in view of quality management, procedures for correction (of operative failure) should be distinguished from those for recurrence.

Chronic posttraumatic stress symptoms after nonsevere stroke

OBJECTIVE

To determine whether posttraumatic stress disorder (PTSD)-related symptoms were present 1 year after a nonsevere stroke and, if so, to examine the relationship between PSTD, coexisting cognitive variables, and infarct localization

METHODS

The authors assessed 49 patients using standard measures of memory, trauma experience, neurologic deficit, depression, anxiety, and PTSD.

RESULTS

Fifteen (31%) patients had significant PTSD symptoms on the Impact of Event Scale (IES > 30). PTSD-like syndrome was independent of neurologic impairment, peristroke amnesia, long-term memory impairment, nosognosia, hypochondriac preoccupations, and physical pain during hospitalization, but was more frequent in women, less educated patients, and patients with more negative appraisals of the stroke experience. Intrusions were increased after basal ganglia strokes, suggesting that the re-experiencing phenomena may be modulated by frontosubcortical pathways.

CONCLUSIONS

Posttraumatic stress disorder symptoms seem frequent in patients with nonsevere stroke and were associated with the subjective intensity of the stroke experience and accompanied by a depressive and anxious state.

[Recurrences of carpal tunnel syndrome in long-term haemodialysis patients]

BACKGROUND

Multiple recurrences of carpal tunnel syndrome and increased malfunction of the hand caused by tendopathies and arthropathies occur in long-term (20 - 30 years) haemodialysis and are mainly influenced by beta2-microglobulin amyloidosis.

METHOD AND CLINICAL MATERIAL

18 patients undergoing haemodialysis for an average of 29 years had been operated on 96 times for bilateral CTS and recurrent CTS during a mean observation period of 12.6 years. In nine patients (12 hands), removal of the thickened flexor digitorum superficialis tendons III and IV had been performed. All but two patients suffered from amyloidosis, 17 of them suffered from additional tendo- and 13 from additional arthropathies. All procedures were performed under local anaesthesia, and in half of them a tourniquet was used. The outcome was evaluated both clinically and with nerve conduction studies.

RESULTS

77 procedures for CTS-recurrences were performed. The first recurrence was observed after an average of 6.1 years (SD 2.8), the second after 4.6 (SD 3.1) and the third after 3.8 (SD 1.9) years. Whereas in case of a first (occasionally second or extremely seldom in a third) recurrence, another re-opening of the carpal tunnel with or without synovectomy, was sufficient to improve symptoms in the majority of patients, this was occasionally the case with a second but rarely with the third recurrence. In these latter patients, only resection of thickened superficial flexor tendon bundles, showing marked amyloid-deposits histologically, resulted in improvement of pain, as well as finger mobility in one third of the patients. The distal motor latency of the median nerve recovered after the primary operation in 86 %, and after the second (first recurrence) only in 53 %. After the third operation (second recurrence), the results after tendon removal were better than in cases after synovectomy alone.

CONCLUSION

In long-term (more than 20 - 30 years) haemodialysis patients suffering from arthropathies, tendopathies and recurrent carpal tunnel syndrome, removal of the flexor digitorum superficial tendons should be considered for the second recurrence to improve pain and finger mobility.

[Carpal tunnel syndrome in haemodialysis patients: analysis of clinical and electrophysiological findings in 268 patients (395 hands)]

PURPOSE/BACKGROUND

Along with arthropathies, carpal tunnel syndrome (CTS) may occur in patients on chronic haemodialysis, its incidence is correlating with the duration of the haemodialysis treatment. To evaluate clinical and electrophysiological findings, relation of the disease to the side of the arteriovenous shunt, gender ratio, and a concurrent tendovaginosis stenosans (TVS), 268 haemodialysis-patients with CTS or recurrent CTS were retrospectively analyzed. METHODS AND (CLINICAL) MATERIAL: Over a period of ten years (1994 - 2003), 268 haemodialysis patients presented to our peripheral neurosurgery practice with CTS or recurrent CTS. Diagnosis was confirmed with clinical and electrophysiological findings. The patients were divided into three groups based on their severity of disease as follows: Patients with only intermittent paraesthesias (CTS I degrees ), with persistent numbness in the area supplied by the median nerve (CTS II degrees ), and with paresis of the thenar muscles (CTS III degrees ). The average distal motor latency (DML), loss of sensory nerve action potentials (SNAP), and/or motor action potentials (MAP) were used as electrophysiological parameters.

RESULTS

During the above mentioned period, 395 primary CTS-operations were performed in 268 patients, and 83 operations of recurrent CTS in 53 patients, i.e. approximately 50 % of the patients had bilateral operations. A second recurrency of CTS was treated in 29 hands of 20 patients and a third recurrency in six hands of five patients. The ratio of women to men suffering from CTS was approximately 1 : 1. TVS occurred concurrent in 22 % of the patients in one hand and in 11.6 % in both hands. Decompression of the median nerve was performed more frequently on the shunt-side, or primarily on the shunt-side, if both hands were affected, as compared to the contralateral side. Recurrency of CTS, possibly a second or third recurrency, was found with increasing time of dialysis. The temporal interval from one operation to the other had a declining tendency. Whereas at the time of the primary operation in 27.4 % of the patients a CTS I degrees was found, patients suffered from CTS II degrees or III degrees in case of a second or third recurrency. Deterioration of clinical signs in CTS recurrency was reflected by the electrophysiological findings with an increasing loss of SNAP and MAP.

CONCLUSION

CTS is a typical complication of chronic haemodialysis, and differs from idiopathic CTS by a gender ratio of 1 : 1, a high frequency of concurrent TVS, as well as a tendency to recur. Since compression of the median nerve was found preferentially on the shunt-side, haemodynamic factors may play a role in the pathogenesis of the disease in addition to amyloidosis. Haemodialysis patients complaining of paraesthesia in their hands should undergo electrophysiological examination, even if a successful CTS-operation was performed in the past.

A prospective study of predictors of poststroke depression

OBJECTIVE

To investigate the association between early depressive behavior after stroke onset and occurrence of poststroke depression (PSD) at 3- and 12-month follow-up evaluations.

METHODS

The study prospectively included 273 patients with first-ever single uncomplicated ischemic stroke. In the stroke unit, nurses scored crying, overt sadness, and apathy daily using an observational method to include patients with comprehension deficits. The Barthel Index was used to assess disability. Follow-up evaluation at months 3 and 12 included psychiatric assessment based on the Diagnostic and Statistical Manual of Mental Disorders, 4th edition.

RESULTS

Crying (19.8%), overt sadness (50.5%), and apathy (47.6%) were observed. Of the patients observed crying, 4 showed pathologic crying, 19 emotionalism, and 12 catastrophic reactions. Crying and overt sadness, but not apathy, were associated with a subjective experience of depression (p < 0.05). Thirty of 52 (58%) patients observed crying, 12 of 19 (63%) patients with emotionalism, and 5 of 12 (41%) patients with catastrophic reactions developed PSD within the first year. Multiple logistic regression analysis showed that only severe functional disability (odds ratio [OR], 4.31; 95% CI, 2.41 to 7.69), crying behaviors (OR, 2.66; 95% CI, 1.35 to 5.27), and an age <68 years (OR, 2.32; 95% CI, 1.30 to 4.13) were (p < 0.05) predictors of late PSD development (13% of the variance).

CONCLUSIONS

In the stroke unit, crying and overt sadness are more reliable indicators of depressed mood than apathy. In patients with first-ever stroke, crying behaviors soon after stroke, a younger age, and severe disability are predictors of poststroke depression occurrence within the first year after stroke onset.

Diseases of the nervous system: patients' aetiological beliefs

BACKGROUND

Patients' opinions about the aetiology of their disease and the implications for compliance have not been well documented at this time.

OBJECTIVE

To investigate prospectively aetiological beliefs of a cohort of neurological inpatients.

METHODS

Within two days of admission, patients orally answered a short questionnaire regarding their beliefs about the aetiology of their disease and the possible influence of psychological factors, stress, fatigue, excessive work or other activities, poor lifestyle, conflict with another person, a tragic event, chance, and destiny.

RESULTS

Of the 342 patients who participated in the study, 49% spontaneously said that they had no idea of what could have caused their disease, 15% gave a congruent medical explanation, 11% mentioned stress and fatigue as a precipitating factor, and 6% evoked a non-congruent medical explanation. Thirty six per cent thought that psychological factors had triggered their disease; such factors being blamed by a higher proportion of young patients and patients with chronic central nervous system diseases. The triggering factors most often blamed were stress (48%, especially by patients with headache), fatigue (51%), chance (54%), and destiny (43%).

CONCLUSIONS

Patients' aetiological beliefs only partially concur with medical opinion and this may influence compliance with treatment. This statement should be explored and confirmed by further studies-for example, in cerebrovascular risk factor follow up.

[Postmastectomy lymphedema and carpal tunnel syndrome. Surgical considerations and advice for patients]

PURPOSE

Following surgery for breast cancer, an increased risk is assumed for development or worsening of lymphedema following hand surgery procedures. The aim of this study was to find out whether surgery performed with exsanguination using a pneumatic tourniquet has any disadvantages under these circumstances. There might result consequences for patients' information of possible risks as well as for performance of hand surgical procedures.

METHOD

52 patients who had undergone mastectomy were included in the study. In 47 of these, axillar lymph node biopsy or dissection had been performed. 41 patients had been advised not to allow measurement of blood pressure, drawing of blood or surgery to that arm. Surgical release of the retinaculum flexorum by using local anesthesia and exsanguination for a maximum of ten minutes was performed at an average of 7.5 (range from 1 - 26) years after the breast operation.

RESULTS

Following release of the carpal ligament a temporary swelling of the arm or hand was found in four patients, which persisted for 2 - 3 months in one patient and disappeared within one week in the others. Three patients suffered from moderate lymphedema before surgery. It was unaffected by hand surgery in two patients and only temporarily worsened for several days in another patient. In all patients, neurological symptoms (paresthesia, numbness and pain) improved completely. Other complications, particularly infections, were not observed.

CONCLUSIONS

1. Exaggerated information of patients with breast surgery in their history does not seem to be indicated in minor hand surgical procedures. 2. The hand surgeon should inform the patients preoperatively that there may occur a transient swelling which can be avoided by loose dressings and early functional training. Using a pneumatic tourniquet has no adverse effect on existing lymphedema in short lasting procedures. 3. Since patients after mastectomy and/or axillary dissection often complain about arm pain and paraesthesia, not only brachial plexus pathology but also a carpal tunnel syndrome must be considered.

Identification of malignant brain edema after hemispheric stroke by PET-imaging and microdialysis

Cerebral blood flow (CBF) and extent of irreversible tissue damage as well as the time course of extracellular concentration of amino acids, substrates of energy metabolism, and purine metabolites, intracranial pressure and tissue oxygen tension were assessed in 34 patients with large strokes covering more than 50% of the MCA territory. The results were compared to findings in the experimental model of transient (for 3 hours) MCA occlusion in cats. In the experimental model as well as in the clinical setting development of malignant brain infarcts (due to formation of space occupying brain edema) was predicted by the size of critically hypoperfused tissue and the volume of irreversibly damaged tissue. The course of malignant infarcts was characterized by progressive increase in concentrations of excitatory amino acids, lactate, pyruvate, glycerol, hypoxanthine and in intracranial pressure, while cerebral perfusion pressure and tissue oxygen tension decreased. These results clearly differentiate a malignant from a benign course of large hemispheric infarction. The methods can be used to identify patients at risk for formation of space occupying edema and to select patients who could benefit from invasive therapeutic strategies.

Fatigue after stroke: a major but neglected issue

Subjective fatigue, defined as a feeling of early exhaustion developing during mental activity, with weariness, lack of energy and aversion to effort, remains virtually unstudied in patients with stroke, bur recent surveys suggest that it is a major, commonly overlooked, stroke sequela. While the few existing series did not show significant correlations between fatigue and stroke severity, lesion location, cognitive and neurological impairment and depression, recent neurobehavioral studies have highlighted an association between fatigue and brainstem and thalamic lesions. This suggests that fatigue may be linked to the interruption of neural networks involved in tonic attention, such as the reticular activating system. In fact, several subtypes of fatigue may develop after stroke, in connection with cognitive sequelae, neurological impairment, psychological factors and sleep disorders. A challenge is to identify and delineate these different subtypes and to distinguish them from mood disorders, which frequently coexist. We emphasize the concept of 'primary' poststroke fatigue, which may develop in the absence of depression or a significant cognitive sequela, and which may be linked to attentional deficits resulting from specific damage to the reticular formation and related structures involved in the subcortical attentional network. In the patients with excellent neurological and neuropsychological recovery, poststroke fatigue may be the only persisting sequela, which may severely limit their return to previous activities. The recognition of poststroke fatigue may be critical during recovery and rehabilitation after stroke.

Predictive value of neurochemical monitoring in large middle cerebral artery infarction

BACKGROUND AND PURPOSE

Space-occupying brain edema is a life-threatening complication in patients with large hemispheric stroke. Early identification of patients at risk is necessary to decide on invasive therapies such as decompressive hemicraniectomy or hypothermia. To assess potential predictors of malignant brain edema by measurement of intracranial pressure (ICP) and microdialysis in patients with large hemispheric stroke and different clinical course.

METHODS

In an ongoing prospective clinical study, an ICP and microdialysis probe were placed into the parenchyma of the ipsilateral frontal lobe of 10 patients. Extracellular concentrations of glutamate, lactate, pyruvate, and glycerol were measured continuously. Repeated cranial CT scans were scrutinized for size of infarction and presence of mass effect.

RESULTS

The dynamics of the different substances varied in accordance with the clinical course, size of infarction, and local brain edema: Increase in ICP and in glutamate concentration and lactate-pyruvate ratio was followed by massive edema and large infarcts; generally low and stable ICP and substrate concentrations were found in patients without progressive space-occupying infarcts.

CONCLUSIONS

In patients with large hemispheric infarction, bedside monitoring with microdialysis is feasible and might be helpful together with ICP recording to follow the development of malignant brain edema.

Multiple interstitial substances measured by microdialysis in patients with subarachnoid hemorrhage

OBJECTIVE

Intracerebral microdialysis is a tool to monitor metabolic disturbances in the brains of patients with severe head injuries or subarachnoid hemorrhage (SAH). In the search for putative indicators of primary and secondary brain damage, we measured multiple metabolites in the dialysates of patients with SAH, to elucidate their significance for the outcomes of the patients as well as their temporal profiles of liberation after the insult.

METHODS

Microdialysis probes were placed, with a ventriculostomy catheter for drainage of cerebrospinal fluid, into a frontal lobe of 10 patients with aneurysmal SAH, for 4.6 +/- 0.5 days. Amino acids, metabolites of glycolysis, purines, catecholamines, and nitric oxide oxidation byproducts were measured by high-performance liquid chromatography. Spearman's correlation coefficient and Student's t test were used to compare the levels of the metabolites with the outcomes of the patients, as assessed using the Glasgow Outcome Scale, 3 months after the ictus.

RESULTS

For patients with unfavorable outcomes (Glasgow Outcome Scale scores of 1-3), which were primarily associated with the development of large infarctions, dialysate levels of excitatory amino acids increased up to 30-fold, those of lactate up to 10-fold, and those of nitrite up to 5-fold, compared with normal levels observed for patients with favorable outcomes (Glasgow Outcome Scale scores of 4 or 5). When average peak concentrations in the dialysates of patients with favorable and unfavorable outcomes were compared, significantly higher levels of excitatory amino acids, taurine, lactate, and nitrite, but not of purines and catecholamines, were observed for those with poor outcomes (P < 0.05). With respect to the temporal profiles of the average metabolite concentrations, the significantly increased levels of amino acids observed for patients with poor outcomes followed a biphasic course, with maximal concentrations on the first and second days or the seventh day after the insult (P < 0.01).

CONCLUSION

These data confirm the usefulness of excitatory amino acids and lactate as major parameters for neurochemical monitoring for patients threatened by acute cerebral disorders. Other substances, such as taurine and nitrite, were also demonstrated to be potentially predictive. Release of these substances into the extracellular fluid of the brain might be particularly relevant for the development of secondary brain damage after SAH, e.g., infarction or brain swelling.

Contribution of anion transporters to the acidosis-induced swelling and intracellular acidification of glial cells

This study examines the contribution of anion transporters to the swelling and intracellular acidification of glial cells from an extracellular lactacidosis, a condition well-known to accompany cerebral ischemia and traumatic brain injury. Suspended C6 glioma cells were exposed to lactacidosis in physiological or anion-depleted media, and different anion transport inhibitors were applied. Changes in cell volume and intracellular pH (pH(i)) were simultaneously quantified by flow cytometry. Extracellular lactacidosis (pH 6.2) led to an increase in cell volume to 125.1 +/- 2.5% of baseline within 60 min, whereas the pH(i) dropped from the physiological value of 7.13 +/- 0.05 to 6.32 +/- 0.03. Suspension in Cl(-)-free or HCO(3)(-)/CO(2)-free media or application of anion transport inhibitors [0.1 mM bumetanide or 0.5 mM 4, 4'-diisothio-cyanatostilbene-2,2'-disulfonic acid (DIDS)] did not affect cell volume during baseline conditions but significantly reduced cell swelling from lactacidosis. In addition, the Cl(-)-free or HCO(3)(-)/CO(2)-free media and DIDS attenuated intracellular acidosis on extracellular acidification. From these findings it is concluded that besides the known activation of the Na(+)/H(+) exchanger, activation of the Na(+)-independent Cl(-)/HCO(3)(-) exchanger and the Na(+)-K(+)-Cl(-) cotransporter contributes to acidosis-induced glial swelling and the intracellular acidification. Inhibition of these processes may be of interest for future strategies in the treatment of cytotoxic brain edema from cerebral ischemia or traumatic brain injury.

Interhemispheric transfer of visual motion information after a posterior callosal lesion: a neuropsychological and fMRI study

Interhemispheric transfer of visual information was investigated behaviourally and with functional magnetic resonance imaging (fMRI) 6 months after a lesion of the posterior two-thirds of the corpus callosum. On tachistoscopical left hemifield presentation, the patient was severely impaired in reading letters, words and geographical names and moderately impaired in naming pictures and colours. In contrast, interhemispheric transfer of visual motion information, tested by verbal report of the direction of short sequences of coherent dot motion presented within the left hemifield, was preserved. The pattern of cerebral activation elicited by apparent motion stimuli was studied with fMRI and compared to that of normal subjects. In normal subjects, apparent motion stimuli, as compared to darkness, activated strongly striate and extrastriate cortex. When presented to one hemifield only, the contralateral calcarine region was activated while regions on the occipital convexity, including putative area V5, were activated bilaterally. A similar activation pattern was found in the patient with a posterior callosal lesion; unilateral left or right hemifield stimulation was accompanied by activation in the contralateral and ipsilateral occipital convexity. Ipsilateral hemifield representation in the extrastriate visual cortex is believed to depend on callosal input. Our observation suggests that this is not the case for visual motion representation and that other, probably parallel, pathways may mediate visual motion transfer after posterior callosotomy.

Mechanisms of arachidonic acid induced glial swelling

Accumulation of arachidonic acid (AA) in the brain during ischaemia may contribute to development of brain oedema. In this study we investigated the effect of selected drugs on AA-induced cytotoxic brain oedema in C6 glioma cells. Suspended C6 glioma cells were preincubated with drugs and AA (0.1 mM) was added. When no drug was administered cell volume increased immediately after the addition of AA with a maximum cell swelling of 13.1+/-1.9% at 15 min (mean +/- S.E. M.). Preincubation of cells with BW 755C, a dual inhibitor of cyclo- and lipoxygenases, showed no reduction in cell swelling from AA, whereas superoxide dismutase, amiloride and the protein kinase inhibitor H-9370 led to a significant attenuation of volume increase (p<0.05). The role of Na(+) ions during cell swelling from AA was evaluated after pretreatment of C6 glioma cells with ouabain. This resulted in a reversal of cell swelling (p<0.01). We conclude that there is potential involvement of free radicals, signal transduction systems and intracellular accumulation of Na(+) ions in glial cell swelling from AA.

Effect of hypothermia on the volume of rat glial cells

1. The cell volume of suspended C6 glioma cells and primary cultured rat astrocytes was measured at normothermia (37 degrees C), and at mild (32 degrees C) and moderate (27 degrees C) hypothermia by flow cytometry with electrical cell sizing. 2. Under control conditions (37 degrees C), C6 glioma cells had a volume of 809 +/- 29 microm3. Moderate hypothermia (27 degrees C) led to rapid cell swelling, with a maximum volume of 113.1 +/- 1.3 % of control being achieved after 50 min. After rewarming to 37 degrees C, cell volume recovered very slowly and incompletely (to 107.2 +/- 0.4 % of control). Less severe hypothermia (32 degrees C) led to a smaller increase in cell volume (108.7 +/- 0.5 % of control). 3. The maximal cell swelling response and the kinetics of swelling were similar in C6 glioma cells and primary cultured astrocytes. 4. Hypothermia-induced cell swelling was dependent on the presence of extracellular Na+ and was reduced by the Na+-H+ antiporter inhibitor EIPA. 5. The underlying mechanisms of hypothermia-induced cell swelling are an intracellular accumulation of Na+ by (1) differential effects of hypothermia on the membrane permeabilities of Na+ and K+ and (2) activation of the Na+-H+ antiporter by a shift of its activation curve to a more alkaline value.

Effect of lactacidosis on cell volume and intracellular pH of astrocytes

Acute traumatic or ischemic cerebral lesions are associated with tissue acidosis leading to cytotoxic brain edema, predominantly affecting astrocytes. Glial swelling from acidosis is believed to be the attempt of cells to maintain a physiological intracellular pH (pHi). However, this concept, potentially important for the development of new treatment strategies for cytotoxic brain edema, has not been validated experimentally. In the present study, cell volume and pHi of astrocytes were measured simultaneously in vitro. Exposure of suspended astrocytes to levels of acidosis found in vivo during ischemia and trauma (pH 6.8-6.2) led to a maximal increase in cell volume of 121.2% after 60 min (n = 5, p < 0.05) and to immediate intracellular acidification close to extracellular levels (pH 6.2, n = 5, p < 0.05). Inhibition of membrane transporters responsible for pHi regulation (0.1 mM amiloride for the Na+/H+ antiporter or 1 mM SITS for HCO3- -dependent transporters) inhibited cell swelling from acidosis but did not affect the profound intracellular acidification. In addition, acidosis-induced cell swelling and intracellular acidification were partly prevented by the addition of ZnCl2 (0.1 mM), an inhibitor of selective proton channels not yet described in astrocytes (n = 5, p < 0.05). In conclusion, these data demonstrate that glial swelling from acidosis is not a cellular response to defend the normal pHi, as had been thought. If these results obtained in vitro are transferable to in vivo conditions, the development of blood-brain barrier-permeable agents for the inhibition of acidosis-induced cytotoxic edema might be therapeutically useful, since they do not enhance intracellular acidosis and thus cell damage.

Relevance of calcium homeostasis in glial cell swelling from acidosis

Tissue acidosis from trauma or ischemia induces cytotoxic brain edema, mainly affecting astrocytes. In vitro, lactacidosis induces a dose-dependent swelling of glial cells. Activation of membrane transporters and channels, also involved in regulation of intracellular pH (pHi), has been identified as underlying mechanism, although details are poorly understood. We have currently studied whether Ca(2+)-ions play a role in acidosis-induced glial swelling and the associated intracellular acidification. The medium pH of a cell suspension (C6 glioma) was lowered from control (7.4) to 6.2 by lactic acid. Cell volume (CV) and pHi were assessed by flow cytometry. During acidosis in normal medium (2.2 mM Ca2+) CV reached a maximum of 125.1%. In a calcium-free medium swelling from acidosis was inhibited by 74%, while additional buffering of intracellular calcium (Ca2+i) by BAPTA-AM had no further effect. Buffering of Ca2+i alone did not affect the CV increase from acidosis at all. pHi which is decreasing during acidosis was not influenced by the above modifications. The present experiments indicate that lactacidosis-induced glial swelling depends on the presence of extracellular Ca(2+)-ions, while alterations of Ca2+i do not seem to be involved.

Role of calcium ions in acidosis-induced glial swelling

Tissue acidosis occurring in cerebral ischemia and traumatic brain injury is a mediator of cytotoxic brain edema. In vitro, extracellular lactacidosis induces swelling of glial cells in a dose dependent manner. pH-regulatory membrane transporters and channels have been identified which are involved in the increase of the glial cell volume. Underlying mechanisms of their activation are poorly understood, however. We have, therefore, addressed the question, whether and how Ca(2+)-ions play a role in acidosis-induced glial swelling and intracellular acidification. For that purpose C6 glioma cells were suspended and the pH in the medium was lowered from 7.4 (baseline) to 6.2 by isotonic lactic acid. Cell volume and intracellular pH (pHi) were assessed by flow cytometry. In the presence of Ca(2+)-ions the cell volume reached a maximum of 125.1% from acidosis. In experiments using a calcium-free suspension medium, cell swelling from acidosis was inhibited by 74%. Additional buffering of intracellular calcium (Ca2+i) had no further inhibitory effect on acidosis-induced cell swelling, while buffering of Ca2+i by BAPTA-AM alone did not affect the glial volume increase secondary to administration of lactic acid. pHi which was decreasing from acidosis was not affected by the experimental modifications of the Ca(2+)-concentration in the medium or cytosol. The present data indicate that lactacidosis-induced glial swelling depends on the presence of extracellular Ca(2+)-ions, while release of Ca(2+)-ions from intracellular stores does not seem to be involved.

Effect of alpha-trinositol on swelling and damage of glial cells by lactacidosis and glutamate

The therapeutic efficacy of alpha-trinositol (D-myo-inositol-1,2,6-trisphosphate), an isomer of the intracellular messenger IP3, was analyzed for cytotoxic swelling and damage of glial cells in vitro from lactacidosis or glutamate. Lactacidosis and the interstitial accumulation of glutamate are prominent sequelae in ischemic or traumatic brain tissue. C6 glioma cells harvested from culture and suspended in a physiological medium were either exposed to pH 5.0 by administration of lactic acid, or to 1 mM glutamate at normal pH. Cell swelling and viability were quantified by blood flow cytometry. Addition of alpha-trinositol (3 mM) under control conditions at pH 7.4 resulted in transient cell shrinking to 96.5 +/- 1.3% of control within 3 min (p < 0.05). Lactacidosis of pH 5.0 led to an increase in cell volume to 139.7 +/- 1.3% within 20 min, whereas alpha-trinositol reduced the swelling response by approximately 25% (p < 0.01). In addition, cell viability was severely affected at pH 5.0 amounting to only 53.8 +/- 3.1% after 60 min. alpha-Trinositol was found to markedly improve cell viability; at 60 min 70.2 +/- 1.6% of the cells were still viable (p < 0.01). Addition of glutamate (1 mM) led to a steady increase in cell size, reaching 110% of control after 120 min, irrespective of wether alpha-trinositol was present or not. The attenuation of cell swelling may be attributed to an interference with pH-regulatory mechanisms, such as the Na+/H(+)-antiporter, while protection of cell viability might be caused be effects of alpha-trinositol on Ca(2+)-overload. On the other hand, the increase in cell volume by glutamate associated with its intracellular uptake was not influenced by alpha-trinositol.

Effect of mild and moderate hypothermia on the acidosis-induced swelling of glial cells

The effect of mild (32 degrees C) and moderate (27 degrees C) hypothermia was analyzed on the cell volume and intracellular pH (pHi) of C6 glioma cells at normal pH and during lactacidosis at pH 6.2 in vitro. The cells were suspended in an incubation chamber under continuous control of pH, PO2 and temperature. Cell swelling was quantified by an advanced Coulter-system. pHi was measured by flow cytometry using the fluorescent dye bis-carboxyethyl carboxyfluorescein (BCECF). Following a control period at 37 degrees C, the ambient temperature was decreased to 32 degrees C for 30 min, and subsequently to 27 degrees C for another 30 min. Hypothermia alone led to an immediate and significant cell volume increase of 107.3 +/- 0.4% (mean +/- SEM) of control after 30 min at 32 degrees C, and further swelling to 110.5 +/- 0.9% after 30 min at 27 degrees C. Yet, hypothermia (27 degrees C) afforded partial protection against the acidosis-induced cell swelling at pH 6.2, which was reaching to 120.4 +/- 0.9% in the normothermic control group after 60 min, while only to 111.3 +/- 0.9% at 27 degrees C. Hypothermia, however, was associated with a more pronounced decrease of the pHi during acidosis (6.3 +/- 0.04) as compared to that of the normothermic control falling then to 6.5 +/- 0.03. The results demonstrate that mild and moderate hypothermia induce glial cell swelling, but simultaneously inhibit cell swelling from acidosis. The protection against cell swelling, however, has its price as indicated by the enhancement of the intracellular acidification.

Role of protein kinase C in acidosis induced glial swelling--current understanding

A major factor in secondary brain injury following cerebral trauma is accumulation of lactic acid resulting in glial swelling. Further, evidence obtained in this context demonstrates activation of protein kinase C (PKC) under these circumstances. Glial swelling from acidosis is attributable to activation of the Na+/H(+)-exchanger, mediating influx of Na(+)-ions in exchange for the extrusion of H+ ions. The antiporter is activated following phosphorylation by PKC. The current study was made to elucidate the role of PKC activation in acidosis-induced glial swelling. For that purpose, suspended C6 glioma cells were used to examine changes of the cell volume and intracellular pH (pHi). Acidosis was induced by administration of isotonic lactic acid. Stimulation of PKC by the phorbol-ester PMA was significantly enhancing glial swelling from severe acidosis (pH 6.2), whereas the decrease of pHi was somewhat attenuated. On the other side, inhibition of PKC by staurosporine did not affect cell swelling nor the decrease of pHi from acidosis. The results indicate that activation of PKC in cerebral trauma or ischemia may enhance glial swelling from lactacidosis.

Sniffing behaviour, or recognizing a lily by smell, but not recognizing a sock on sight

We report a 65-year-old man with a post-anoxic encephalopathy who showed compulsive sniffing at available objects. This stereotyped environment-driven behaviour has not been previously described. Other compulsive environment-driven responses, such as manipulation and utilization of tools and hyperlexia, were also present. The disorder shared several features with the Klüver-Bucy syndrome where mouthing of objects, rather than smelling them, is common. The patient had a severe dementia, with amnesia, anomia, apraxia, and visual agnosia. Whereas he could not recognize very familiar objects on sight, he could in contrast correctly identify several familiar odours. Although sniffing was a compulsive and purposeless environment-driven behaviour, the question may be asked whether a relatively preserved olfactory recognition, in the presence of a severe disorder of visual recognition and knowledge, could have favoured a stereotyped exploration of objects by smelling.

Swelling and damage of glial cells by lactacidosis and glutamate: effect of alpha-trinositol

The therapeutical efficacy of alpha-trinositol (D-myo-inositol-1,2,6-trisphosphate), an isomer of the intracellular messenger IP3, was analyzed on cytotoxic swelling and damage of glial cells in vitro from lactacidosis or glutamate. C6 glioma cells suspended in a physiological medium were either exposed to pH 5.0 by administration of lactic acid, or to 1 mM glutamate. Cell swelling and viability were quantified by flow cytometry. Lactacidosis of pH 5.0 led to an increase in cell volume to 139.7 +/- 1.3% within 20 min whereas alpha-trinositol was reducing the swelling response by approximately 25% (P < 0.01). In addition, at pH 5.0 the fraction of viable cells was lowered from 94.3 +/- 0.2% (control) to only 53.8 +/- 3.1% after 60 min. Alpha-trinositol was found to protect also cell viability; at 60 min of lactacidosis 70.2 +/- 1.6% of the cells still were viable (P < 0.01). The addition of glutamate (1 mM) to the cell suspension led to a steady increase in cell size, reaching 110% of control at 120 min, irrespectively of whether alpha-trinositol was added or not.

The effect of dietary alpha-tocopherol on the experimental vasogenic brain edema

It has become increasingly obvious that free radicals and lipid peroxidation contribute to brain damage from trauma by mediating edema formation and ischemia. It should, therefore, be expected that the actual level of endogenous antioxidants, as for example, vitamin C and E in plasma, has an influence on the extent of free radical-induced injury. In this communication we investigate the effect of dietary changes in the free radical scavenger alpha-tocopherol on posttraumatic cerebral swelling in Sprague-Dawley rats. Low, normal, and high plasma levels of alpha-tocopherol were established by respective diets supplied over 2 weeks. Animals of all groups received the same food without alpha-tocopherol. One group was fed a vitamin E-free diet. The pellet-food for the other animals was supplemented either with 5-mg alpha-tocopherol/100 g or 250-mg alpha-tocopherol/100 g dry mass, respectively. The vitamin E-free diet lowered the alpha-tocopherol level in plasma to 30% of control, whereas supplementation with 250 mg/100 g led to a plasma concentration of 200% of control. The animals were then subjected to a focal cold injury of the left cerebral hemisphere. Twenty-four hours after trauma the brain was removed and the water content of each hemisphere was determined by the wet-dry weight method. Swelling of the traumatized hemisphere was calculated as the difference in weight between the traumatized and contralateral control hemisphere. The 2-week alpha-tocopherol supplementation or -deletion diet, respectively, did not either afford significant reduction or lead to an enhancement of traumatic brain swelling. Likewise, the increase in brain water content of the traumatized hemisphere was not affected. It is concluded that supplementation or depletion of alpha-tocopherol for 2 weeks, resulting in a marked increase or decrease of the vitamin E plasma level, does not influence formation of posttraumatic vasogenic brain edema.

Anoxia in vitro does not induce neuronal swelling or death

To improve the understanding of neuronal cell swelling in cerebral ischemia, cell volume regulation, viability, intracellular electrolytes, and lactate production of Neuro-2A neuroblastoma cells were studied using an in vitro model. The volume regulatory capacity of Neuro-2A cells was assessed after incubation in hypo- and hypertonic media. Anoxia was studied alone and together with inhibition of glycolysis by iodoacetate. Reducing the tonicity of the incubation medium to 250, 200, or 150 mosm/l caused immediate swelling followed by a regulatory volume decrease within 20 min, which, however, was not complete. The final cell volume after regulation depended on the tonicity of the medium and remained above control. There was no regulatory volume increase after cell shrinking in hypertonic media. Despite the severe anisotonic incubation, viability decreased only slightly without reaching statistical significance. In contrast to in vivo conditions, anoxia for 90 min with or without iodoacetate for additional inhibition of anaerobic energy metabolism neither caused neuronal cell swelling nor a decrease of viability. Reoxygenation after the anoxic period also did not induce volume and viability changes. Intracellular K+ of Neuro-2A cells was markedly decreased, while Na+ increased in a 1:1 ratio during complete energy failure by anoxia plus iodoacetate. A similar effect, occurring however somewhat delayed, was seen when the Neuro-2A suspension was exposed to iodoacetate alone. Anoxia without inhibition of glycolysis had no effect on intracellular ion concentrations, but lactate production was nearly six times higher than normal. In vitro, with a large extracellular volume and sufficient glucose supply, the energetic demands of Neuro-2A cells to maintain stable transmembraneous ion gradients during anoxia are obviously met by anaerobic glycolysis. The current results confirm that neuronal cells are able to adequately regulate cell volume in response to hyposmotic stress. On the other hand, maintenance of a normal cell size during complete energy deprivation suggests strongly that energy failure per se does not suffice to induce neuronal swelling. Cell swelling in cerebral ischemia in vivo thus appears a secondary phenomenon due to mediator mechanisms such as tissue acidosis or elevated extracellular glutamate levels.

Effect of photodynamic treatment of human endothelial cells on cell volume and cell viability

Photodynamic therapy (PDT) has yielded promising results in the treatment of malignant tumors. However, the mechanisms leading to tumor destruction during PDT are still not completely understood. In addition to effects on the microcirculation, damage to cellular structures has been observed following exposure of cells to PDT. A phenomenon preceding these events might possibly be cell swelling. We therefore studied the influence of treatment with Photofrin(R) (PF) and laser light on volume changes and cell viability of endothelial cells. Endothelial cells were obtained from human umbilical cord veins (HUVEC) by an adaption of the method of Maruyama. After subcultivation the cells were harvested and transferred as a cell suspension into a specially designed incubation chamber. Cells received either PF in concentrations of 1.5 or 3.0 mu g/ml and laser illumination 60 min post incubation (630 nm; 40 mW/cm(2), 4 Joule), PF alone, or laser treatment only. Following start of PF incubation and after phototreatment cell samples were taken for volume measurements using flow cytometry, and for studies of cellular morphology using scanning electron microscopy. Simultaneously, cell viability was monitored by the trypan blue exclusion test and the colorimetric MTT assay. Both control groups, HUVEC receiving PF or laser treatment alone, revealed constant cell volumes and cell viability during the entire course of the experiment. After PDT (60 min post-incubation) with 1.5 and 3.0 mu g PF/ml cell volume of HUVEC was increased at 15 min to 122%+/-6% and 140%+/-10% of baseline (100%), at 60 min to 152%+/-9% and 134%+/-18%, respectively (p<0.01). The number of viable cells was significantly reduced of samples treated with 1.5 and 3.0 mu g PF/ml at 15 min after PDT to 81%+/-3% and 76%+/-10% of baseline (100%), at 60 min after PDT to 32%+/-14% and 20%+/-15%, respectively (p<0.01). Scanning electron microscopy of cells exposed to PDT following 60 min incubation with Photofrin (3.0 mu g/ml) revealed significant cell damage. At the highest PF concentration HUVEC showed loss of microvilli and formation of blebs on the cellular surface. Our study demonstrates that PDT induces a significant increase in endothelial cell volume and a loss of cell viability. We suggest that swelling and damage of endothelial cells following PDT is a primary event finally contributing to cessation of blood flow and subsequent necrosis of tumors.

Swelling, intracellular acidosis, and damage of glial cells

Cerebral ischemia and severe head injury among others are associated with a limited availability of oxygen, leading to cell catabolism as well as anaerobic glycolysis. Resulting metabolites, such as arachidonic- and lactic acid, can be expected to leak into perifocal brain areas, contributing there to cytotoxic swelling and damage of neurons and glia. Since elucidation of mechanisms underlying cell swelling and damage in the brain is difficult in vivo, respective investigations were carried out in vitro using suspended glial cells. Thereby, effects of arachidonic acid (AA) and of lactacidosis on glial cell volume, intracellular pH (pHi), and cell damage were analyzed utilizing flow cytometry. AA led to an immediate, dose dependent swelling and intracellular acidosis of glial cells. A concentration of 0.1 mM increased cell volume to 110% of control and decreased pHi to 7.05. Whereas glial swelling was permanent, pHi recovered to baseline after 90 min. Cell viability of 90% remained unchanged after addition of AA up to 0.1 mM, while at 0.5 mM it was significantly decreasing. Glial swelling from AA was nearly completely inhibited by the aminosteroid U-74389F or by using a Na(+)-free suspension medium for the experiment. Acidification of the medium to pH 6.8 or 6.2 led to a cell volume of 110% or 120% of control without affecting cell viability. The cells were not capable to defend their normal pHi during lactacidosis of the suspension medium but became acidotic as well. Addition of amiloride or utilization of Na(+)-free medium inhibited cell swelling from lactacidosis, while intracellular acidosis was even more pronounced. The results indicate that AA as well as acidosis are potent mediators of glial swelling and damage at levels found under pathophysiological conditions in the brain in vivo. Whereas intracellular acidification caused by AA was reversible, glial cells were unable to regulate their pHi during maintenance of extracellular acidosis. Concerning the mechanisms of glial swelling by AA, the production of oxygen- and lipid radicals might play a major role in the swelling process. The results indicate a role of the Na+/H(+)-antiporter in acidosis-induced glial swelling, whereas the exchanger has a limited significance for maintenance of pHi. As seen, the final pathway of glial swelling from both, AA and lactacidosis, requires a net influx of Na(+)-ions, probably together with Cl-ions, and osmotically obliged water.

Clearance and metabolism of arachidonic acid by C6 glioma cells and astrocytes

Effects of increased levels of arachidonic acid (AA) were analyzed in vitro by employment of C6 glioma cells and astrocytes from primary culture. The cells were suspended in a physiological medium added with arachidonic acid (AA) in a concentration range from 0.01 to 0.5 mM. The concentration profiles of the fatty acid and AA-metabolites were subsequently followed for 90 min. AA was measured by gas chromatography, whereas the AA-metabolites PGF2 alpha and LTB4 by radioimmunoassay (RIA). Following administration of AA at 0.05 or 0.1 mM the medium was completely cleared from the fatty acid within 10 to 15 min. However, when 0.5 mM were added, AA concentrations of 0.36 +/- 0.055 mM were found at 20 min, while 0.275 +/- 0.045 mM at 90 min. Addition of AA (0.1 mM) to cell-free medium was also associated with a steady decline of its concentration, although the decrease was markedly delayed as compared to the clearance in the presence of glial cells. AA was subjected to dose-dependent metabolisation in the cell suspension as demonstrated by the production of PGF2 alpha and LTB4. Following addition of 0.01 or 0.5 mM, concentrations of PGF2 alpha increased to a 1.9- or 4.9-fold level within 10 min, whereas those of LTB4 rose to a 1.3- or 33.7-fold level. This was attenuated or completely blocked, respectively, by the cyclo- and lipoxygenase inhibitor BW 755C. Formation of both metabolites from AA was also observed when studying astrocytes from primary culture. The current findings demonstrate an impressive efficacy of C6 glioma cells and astrocytes to clear arachidonic acid from the suspension medium and to convert the lipid compound into prostaglandins and leukotrienes. Uptake and metabolisation of AA by the glial elements may play an important role in vivo, for example in cerebral ischemia.

Treatment of vasogenic brain edema with the novel Cl- transport inhibitor torasemide

The efficacy of the diuretic agent torasemide, which antagonizes the Na+/K+/Cl- cotransport and Cl- channels, was investigated to determine its inhibition of brain edema from a focal cerebral lesion. For this purpose, cold injury of the brain was induced in 50 Sprague-Dawley rats while monitoring arterial blood pressure. The brain was removed for gravimetric assessment of swelling of the traumatized hemisphere 24 h after trauma. The water content was also determined after drying the cerebral hemispheres for 24 h. Animals were divided into five groups. A control group with trauma received vehicle only; two other groups received 1.0 or 10.0 mg torasemide/kg body weight 30 minutes before and 6 h after trauma (n = 10-12). Administration of the drug after the insult was also investigated in animals with application of vehicle or 10.0 mg/kg of torasemide at 30 minutes and 6 h following the brain lesion (n = 8). Torasemide did not affect important physiologic variables, such as the arterial pO2, pCO2, pH, hemoglobin, hematocrit, or plasma osmolality, while increasing blood pressure (p < 0.01). The blood pressure response notwithstanding, treatment significantly attenuated hemispheric brain swelling from trauma. In control animals without treatment, cold injury led to hemispheric swelling of 8.89%. In animals with 1 mg torasemide/kg BW, brain swelling amounted to 8.51% and to 7.04% in animals receiving 10 mg/kg before and after the insult (p < 0.005). Treatment was also found to attenuate the increase in tissue water content from trauma, but without reaching statistical significance. Postinsult treatment with torasemide (10 mg/kg BW) at 30 minutes and 6 h after trauma was again associated with a significant reduction in hemispheric brain swelling, which in this group amounted to 7.46% compared with 9.76% in the untreated controls (p < 0.005). The increase in the cerebral water content from trauma was also significantly blunted in the latter experiments (p < 0.01). The present data indicate a remarkable therapeutic potential of the novel diuretic agent torasemide to reduce vasogenic brain edema from an acute cerebral lesion. It is surmised that the compound specifically interferes with Cl- transport mechanisms, which apparently are activated in edematous brain involving neuronal and glial cells, for example. This conclusion is supported by in vitro observations that torasemide inhibits the swelling of glial cells from acidosis. On the other hand, it is unlikely that gross dehydration of the brain secondary to the induction of diuresis by the agent played a role, because hematocrit and plasma osmolality were not found to be affected.

Swelling, acidosis, and irreversible damage of glial cells from exposure to arachidonic acid in vitro

Swelling and damage of C6 glioma cells and of primary cultured astrocytes were analyzed in vitro during incubation with arachidonic acid (AA; 20:4). The cells were suspended in a physiological medium supplemented with AA at concentrations of 0.001-1.0 mM. Cell swelling was quantified by flow cytometry with hydrodynamic focusing. Flow cytometry was also utilized for assessment of cell viability by exclusion of the fluorescent dye propidium iodide and for measurement of the intracellular pH (pHi) by 2',7'-bis-(2-carboxyethyl)-5(and -6)carboxy-fluorescein. Administration of AA caused an immediate dose-dependent swelling of C6 glioma cells, even at a concentration of 0.01 mM. At this level cell volume increased within 20 min to 105.0% of control, at 0.1 mM to 111.0%, while at 1.0 mM to 123.7%. Following a phase of rapid cell volume increase, swelling leveled off during the subsequent observation period of 70 min. Viability of the C6 glioma cells was 90% under control conditions. It remained unchanged after raising AA concentrations to 0.1 mM. At 0.5 mM, however, cell viability fell to 72.8%, and at 1.0 mM to 32.7%. pHi of the glioma cells was 7.3 under control conditions. In parallel with the early swelling phase, AA led to a dose-dependent decrease of the intracellular pH and an elevated lactate production of the cells. During incubation with 0.1 mM AA, pHi decreased to 7.06 after 5 min, but recovered to normal subsequently. In addition, swelling-inducing properties of linoleic (18:2) or stearic (18:0) acid were analyzed for evaluation of the specificity of glial swelling induced by AA. Whereas stearic acid (0.1 mM) failed to induce a swelling response, linoleic acid (0.1 mM) was found to be effective. The volume increase of the glial cells, however, was only half of that found during exposure to AA at the same concentration. Further, glial swelling from AA or linoleic acid was completely inhibited by the aminosteroid U-74389F, an antagonist of lipid peroxidation. Finally, omission of Na+ ions in the suspension medium with replacement by choline led also to inhibition of the cell volume increase by AA. Experiments using astrocytes from primary culture confirmed the swelling-inducing properties of AA at a quantitative level, whereas vulnerability of the cells to AA was increased. The present results demonstrate an important role of AA in cytotoxic swelling and irreversible damage of glial cells at concentrations that occur in vivo in cerebral ischemia or trauma.(ABSTRACT TRUNCATED AT 250 WORDS)