Movement disorders after hypoxic brain injury following cardiac arrest in adults.

BACKGROUND AND PURPOSE: Post-hypoxic movement disorders and chronic post-hypoxic myoclonus are rare complications after cardiac arrest in adults. Our study investigates the clinical spectrum, neuroimaging results, therapy and prognosis of these debilitating post-hypoxic sequelae. METHODS: This retrospective study included 72 patients from the neurological intensive care unit at a university hospital, who were diagnosed with hypoxic-ischaemic encephalopathy after cardiac arrest between January 2007 and September 2018. Clinical records were screened for occurrence of post-hypoxic movement disorders and chronic post-hypoxic myoclonus. Affected patients were further analysed for applied neuroprognostic tests, administered therapy and treatment response, and the outcome of these movement disorders and neurological function. RESULTS: Nineteen out of 72 screened patients exhibited post-hypoxic motor symptoms. Basal ganglia injury was the most likely neuroanatomical correlate of movement disorders as indicated by T1 hyperintensities and hypometabolism of this region in magnetic resonance imaging and positron emission tomography computed tomography. Levomepromazine and intrathecal baclofen showed first promising and mostly prompt responses to control these post-hypoxic movement disorders and even hyperkinetic storms. In contrast, chronic post-hypoxic myoclonus best responded to co-application of clonazepam, levetiracetam and primidone. Remission rates of post-hypoxic movement disorders and chronic post-hypoxic myoclonus were 58% and 50%, respectively. Affected patients seemed to present a rather good recovery of cognitive functions in contrast to the often more severe physical deficits. CONCLUSIONS: Post-hypoxic movement disorders associated with pronounced basal ganglia dysfunction might be efficiently controlled by levomepromazine or intrathecal baclofen. Their occurrence might be an indicator for a more unfavourable, but often not devastating, neurological outcome.

Nonviral gene delivery of erythropoietin by mesenchymal stromal cells.

Erythropoietin (EPO) acts on erythroblasts in the bone marrow (BM) to stimulate the formation of red blood cells. In this study, we wanted to determine whether BM-derived mesenchymal stromal cells (MSCs) can be used as cellular vehicles to deliver EPO in mice without the use of viral vectors. After isolation and characterization of murine MSCs (mMSCs), different transient transfection procedures were compared for their efficacy of gene transfer of the pEGFP-N2 plasmid. Nucleofection outperformed magnetofection and lipofection. Stably transfected mMSCs were generated by selection with G418-disulfate and single-cell-colony-forming unit (sc-CFU) assays without changes in their proliferation capacity and osteogenic/adipogenic differentiation potential. Next, murine EPO was stably introduced into mMSCs by nucleofection of a plasmid encoding the epo and egfp genes. Intraperitoneal transplantation of EPO-expressing mMSCs increased serum EPO levels, hematocrit and hemoglobin of C57BL/6 mice within 1 week. The hematocrit remained elevated for 5 weeks, but production of antibodies against both transgenes was detected in the hosts and serum EPO levels normalized. Our results suggest that nonviral gene delivery into MSCs can be used to enhance the known beneficial effects MSCs by additional production of therapeutic factors like EPO in vivo.

"Heidelberg standard examination" and "Heidelberg standard procedures" - Development of faculty-wide standards for physical examination techniques and clinical procedures in undergraduate medical education.

The competent physical examination of patients and the safe and professional implementation of clinical procedures constitute essential components of medical practice in nearly all areas of medicine. The central objective of the projects "Heidelberg standard examination" and "Heidelberg standard procedures", which were initiated by students, was to establish uniform interdisciplinary standards for physical examination and clinical procedures, and to distribute them in coordination with all clinical disciplines at the Heidelberg University Hospital. The presented project report illuminates the background of the initiative and its methodological implementation. Moreover, it describes the multimedia documentation in the form of pocketbooks and a multimedia internet-based platform, as well as the integration into the curriculum. The project presentation aims to provide orientation and action guidelines to facilitate similar processes in other faculties.

Biochemical differences between perilymph, cerebrospinal fluid and blood plasma in the guinea pig.

Seven selected biochemical substances were systematically analyzed in perilymph (PL), cerebrospinal fluid (CSF) and blood plasma or serum of anesthetized guinea pigs in order to compare the composition of these fluids with regard to the origin and biochemical nature of PL. Compositional differences between the fluids were expressed by PL/CSF and PL/plasma concentration ratios of the chemical components measured. Contrary to the prevailing notion, the results suggest that the specific biochemical composition of PL corresponds neither to that of CSF nor to that of a simple ultrafiltrate of blood plasma. Furthermore, except for the total protein concentration, no significant differences were found in the composition of PL between the scala tympani and scala vestibuli.

Intensity-dependent changes in oxygenation of cochlear perilymph during acoustic exposure.

This study examined the effects of acoustic exposure at different intensities on local oxygenation of the cochlea. The oxygen partial pressure (pO2) of perilymph in the basal scala tympani was measured polarographically in anesthetized guinea pigs exposed to either wide-band noise at 85 dB SPL or a 10 kHz pure tone at 90, 105, or 125 dB SPL for 1 h. Cochlear temperature, heart rate, arterial blood pressure and acid-base status were monitored. The cochlear microphonics (CM) and compound action potentials (CAP) were recorded before and after exposure. There were clear intensity-dependent differences in the effect of acoustic exposure on perilymphatic oxygenation. Moderate exposure intensities (85-90 dB SPL) were found to increase the pO2 by an average of about 20% of the initial level. In contrast, high intensity acoustic exposure (125 dB SPL) resulted in a mean decrease of about 20%. These changes persisted within a subsequent 30-min post-exposure period. There was no significant change in cochlear temperature and cardiorespiratory variables during and after any of the exposures as compared to the controls. CM and CAP amplitudes showed an extensive loss after acoustic overstimulation (125 dB SPL), but no permanent change with lower exposure intensities. These findings suggest that intracochlear oxygenation plays an important role in inner ear physiology during acoustic stimulation.

Sound-induced artifact in cochlear blood flow measurements using the laser Doppler flowmeter.

The laser Doppler flowmeter has been shown to give a response from the cochlea during high intensity acoustic stimulation which is not related to blood flow through the cochlea. The magnitude of this response depends upon the intensity and frequency of stimulation and the location of the probe on the cochlea. Evidence is presented that the response is derived from the vibration of cochlear tissue and/or the bony cochlear shell during acoustic stimulation.

[Electrophoretic examination of protein distribution in guinea pig perilymph]. / Elektrophoretische Untersuchungen zur Proteinverteilung in der Meerschweinchen-Perilymphe

Perilymph and serum of guinea pigs were investigated using immunoelectrophoresis and polyacrylamide gel electrophoresis. The molecular weights of the perilymph proteins were estimated by electrophoresis in a linear polyacrylamide gel gradient (3-20%). The immunoelectropherograms and the polyacrylamide gel electropherograms of equivalent amounts of perilymph protein and serum protein are nearly the same. The immunological detection of the perilymph proteins indicates that they are serum proteins. The clear identification of the individual proteins fails because of missing monospecific antisera against the individual proteins of guinea pig. High-molecular proteins (range of the molecular weight estimation 67 000-290 000) are also detectable in the perilymph according to the molecular weight estimation.

[Protein concentration in the guinea-pig perilymph]. / Zur Proteinkonzentration der Meerschweinchen-Perilymphe

The protein concentration of the guinea pig perilymph was investigated systematically using a micro-modification of the method of Lowry et al. Perilymph of scala vestibuli and of scala tympani was obtained from living animals and immediately post mortem by various methods. In living animals it is especially difficult to obtain samples without blood contamination. Another problem in the obtaining of perilymph from living animals is the contamination of tympanic perilymph samples with cerebrospinal fluid. This contamination diminishes the protein concentration of perilymph to a high degree. When the subarachnoid space is opened suboccipitally before perilymph extraction, there is no significant difference between protein content in tympanic and vestibular perilymph. The mean protein concentration in both cochlea scales is about 150 mg/100 ml. When samples are extracted post mortem from animals perfused intra-arterially, mean values of protein are in the same range. Without perfusion of animals, the mean value of tympanic samples extracted post mortem is significantly higher. Causes of artefacts in perilymph investigations are discussed.

[Protein concentration of perilymph in guinea pigs after noise exposure]. / Proteinkonzentration der meerschweinchen-perilymphe nach schallbelastung

The protein concentration in the perilymph of noise-exposed guinea pigs was investigated using a micromethod described previously. The animals were exposed to wide band noise at 140 dB for one hour unilaterally in a closed acoustic system. Perilymph was obtained after exposure at different intervals: immediately, 6 or 24 hours later. From animals exposed to noise, it is particularly more difficult to obtain perilymph without blood contamination than from normal ones. Even post mortem, it is difficult to obtain samples without blood contamination and without hemolysis, particularly from the scala tympani. Therefore, some animals were perfused intra-arterially with Ringer solution or with Infukoll M 40 before decapitation. After exposure to noise only a small increase in protein concentration of the perilymph can be detected in the noise-exposed ears of animals perfused intra-arterially. The difference in concentration is most distinct in samples extracted 6 hours after noise exposure had ceased. No reliable clue to the source of this protein could be obtained from these investigations.

[Microflame-photometric estimation of sodium and potassium for testing the purity of inner ear fluids (author's transl)]. / Mikroflammenphotometrische Natrium-, Kaliumbestimmung zur Reinheitskontrolle von Innenohrflüssigkeiten.

A simple micromodification of simultaneous flame-photometric estimation of sodium and potassium concentration in sample volumes of 0.1 microliter is described for testing the purity of inner ear fluids, especially of perilymph. The precision of the method is about 10% (calibration standards, Table 2) and depends mainly on the precision of measuring the small sample volumes. The method has been used for examining cerebrospinal fluid, perilymph, and endolymph samples of guinea pigs. The increased perilymphatic potassium (Fig. 1a) and endolymphatic sodium values suggest a more or less substantial contamination of the tested samples and underline the necessity of checking the purity of inner ear fluid samples which are used in biochemical analysis.

Changes in cochlear oxygenation, microcirculation and auditory function during prolonged general hypoxia.

Changes in cochlear microcirculation and oxygenation and auditory function were examined in anesthetized guinea pigs during prolonged hypoxic ventilation (8% oxygen in nitrogen) for 1 h. Cochlear blood flow and perilymphatic oxygen partial pressure were measured using laser Doppler flowmetry and oxygen-sensitive microelectrodes. Auditory function was examined by recording cochlear microphonics, compound action potentials and auditory evoked brainstem response. Blood pressure and heart rate were monitored. During systemic hypoxia, the perilymphatic PO2 dropped on average to about 70% of the initial value. Cochlear and brainstem potentials showed a mean reduction to 75-82%. Different effects of hypoxia on cochlear blood flow were observed and included decreases as well as increases. Mean arterial blood pressure declined significantly during hypoxia, while the heart rate remained constant. The changed variables returned to normal during reventilation with room air. The findings are discussed with regard to their significance as an animal model for the study of hypoxia-induced cochlear pathophysiology.

Intensity-related changes in cochlear blood flow in the guinea pig during and following acoustic exposure.

This study examined the effects of acoustic exposure at different intensities on cochlear blood flow (CBF) using laser Doppler flowmetry. CBF was measured in anesthetized guinea pigs exposed to either a 10 kHz pure tone at 125, 105, or 90 dB SPL, or wide-band noise at 85 dB SPL for 1 h. Mean arterial blood pressure and heart rate were recorded continuously. Arterial acid-base status, cochlear temperature, cochlear microphonics (CM), and compound action potentials (CAP) were measured before and after exposure. There was a small, but significant, steady decline in basal CBF after 40 min loud sound exposure (125 dB SPL), but no change in basal CBF occurred with the lower intensities (85-105 dB SPL). In contrast, there was a significant increase in apical CBF after 1 h exposure to either moderate wideband noise (85 dB SPL) or a 10 kHz tone at 105 dB SPL. These changes persisted during a 20-min post-exposure period. In most cases, the cochlear temperature and cardiorespiratory variables monitored remained unchanged during and after the exposures as compared to the controls. CM and CAP amplitudes showed extensive losses after acoustic overstimulation (125 dB SPL), but no permanent changes were found at the lower intensities used. The present findings confirm the occurrence of intensity-related effects of acoustic exposure on the cochlear microcirculation.

[Total lactate dehydrogenase activity of perilymph, plasma and cerebrospinal fluid in unstressed and noise stressed guinea pigs]. / Zur Gesamtaktivität der Laktatdehydrogenase von Perilymphe, Plasma und Liquor cerebrospinalis unbelasteter und schallbelasteter Meerschweinchen.

The total activity of lactate dehydrogenase (LDH) of perilymph (PL), plasma, and cerebrospinal fluid (CSF) of unexposed and sound-exposed guinea pigs was examined with due consideration of the principal sources of error. To test the purity of PL samples, protein, potassium, and sodium were determined simultaneously (Table 1). The LDH was analysed fluorometrically. It was found that there are considerable differences in the LDH activities of PL, CSF, and plasma (Table 2). The mean activity of PL was three to four times higher than that of CSF and only about half that of plasma. No significant difference was found between the PL in scala tympani and scala vestibuli. The most frequent LDH values of the individual fluids (Fig. 2) were somewhat lower than the mean values calculated. Immediately (less than or equal to 60 min) after exposing the animals to wide-band noise at an intensity of 140 dB SPL for 10 min, the mean PL values of the scala tympani and scala vestibuli were found to be somewhat higher than in unexposed animals (Table 3). Eighteen hours after the exposure, slightly higher activity was only detectable in PL of the scala vestibuli. The differences were not found to be significant. The LDH values of CSF and plasma remained unchanged both less than or equal to 60 min and 18 h after noise exposure.

Preventive effect of magnesium supplement on noise-induced hearing loss in the guinea pig.

The effect of magnesium (Mg) on noise-induced hearing loss was investigated in two groups of adult pigmented guinea pigs maintained either on optimal or suboptimal (physiologically high or low) Mg produced by different diets. The total Mg concentrations of the perilymph (PL), cerebrospinal fluid, blood plasma and red blood cells were measured by atomic absorption spectrometry and were found to differ significantly between the two groups (P < 0.01). One ear of each animal was exposed to either a single shooting impulse at a peak pressure level of 187 dB or two impulse noise series at a rate of 1/s and peak pressure levels of 150 dB (1,000 impulses) and 167 dB (2,280 impulses), respectively. Temporary (TTS) and permanent (PTS) hearing threshold shifts in anesthetized animals were measured 2 h and 1 week after the noise exposure, using auditory brain stem response (ABR) audiometry at a frequency range from 3.75 to 30 kHz. Exposure to the single noise impulse resulted in a mean TTS that was significantly lower in the high Mg group than that in the low Mg group (P < 0.05), although no substantial PTS was observed in either group. In the animals exposed to 150 dB noise, the TTS showed a tendency towards an Mg-related reduction at the higher frequencies. A small difference in PTS was found between the low Mg and high Mg groups, but was not significant. Exposure to the 167-dB noise series caused a considerable TTS, which was significantly lower in the high Mg group at 7.5 and 15 kHz than in the low Mg group (P < 0.05). The mean PTS showed a significant difference between the two Mg groups over the whole frequency range (P < 0.05) and was found to correlate negatively with the total Mg concentrations of both PL and plasma (P < 0.05). Moreover, the high Mg group showed a faster recovery from the hearing threshold shift than the low Mg group. The present findings show that preventive oral Mg supplements can significantly reduce the rate of acoustic trauma caused by high-level impulse noise exposure in the guinea pig.

Total magnesium concentrations of perilymph, cerebrospinal fluid and blood in guinea pigs fed different magnesium-containing diets.

The total magnesium (Mg) concentrations of the perilymph (PL), cerebrospinal fluid (CSF), plasma and red blood cells (RBCs) of anesthetized guinea pigs separated into three groups and fed different Mg-containing diets were determined by atomic absorption spectrometry. Due consideration was given to the significant sources of error connected with the sampling procedure, particularly contamination of PL with CSF. The Mg levels of the individuals fluids differed significantly (P < 0.05/0.01) within each group. In the normal Mg group, the mean values of the PL, CSF and plasma were 0.66, 0.81 and 0.97 mmol/l, respectively, and 7.83 mmol/kg dry weight for RBCs. The analytical data were found to depend on the Mg content of the animals' diet, but to a different degree in the individual specimens (plasma > PL > CSF). A correlation was found to exist between all specimens tested (P < 0.05/0.01), except for CSF and RBCs, with the closest relation being that between plasma and PL. These findings suggest that the perilymphatic Mg equilibrates with the Mg level of plasma rather than with that of CSF. This is the first report showing Mg data of PL, CSF, plasma and RBCs obtained from the same subject, and the dependency on the Mg content of the animals' diet.

[Comparative studies of lactate concentration in the perilymph, blood and cerebrospinal fluid of normal and sound exposed guinea pigs (author's transl)]. / Vergleichende Untersuchungen der Laktatkonzentration von Perilymphe, Blut und Liquor cerebrospinalis normaler und schallbelasteter Meerschweinchen

The paper deals with comparative studies of lactate concentration in the perilymph (PL) of scala tympani and of scala vestibuli, arterial and venous blood, serum and cerebrospinal fluid (CSF) of normal and sound exposed guinea pigs, special consideration having been given to possible sources of error in the methods employed. Lactate was determined enzymatically using a micromodification of the Boehringer UV-test combination adapted to 1 mul PL. The lactate concentrations in the PL of scala tympani and scala vestibuli did not differ significantly. The mean values amounted to 4.5-5.2 mM/l in the case of the opened and of the unopened subarachnoid space (Table 1). The lactate concentrations in the PL of both cochlea scales were significantly higher already ten minutes post-mortem. In the exposure experiments the animals were unilaterally exposed to sound for 1 h in an acoustically isolated system using a wide-band noise at an intensity of 120 dB SPL for one series and 2-kHz pure-tone at intensities of 112 and 122 dB SPL for two other series. We did not detect any changes in the lactate concentrations neither in the PL nor in the blood and in the CSF, following sound exposure (Table 2 and 3). The lactate concentrations of arterial and venous blood and CSF did not differ significantly. The mean values amounted to 1.4-1.8 mM/l (Table 2). However, if blood was not deproteinized or centrifuged immediately after being taken, the lactate concentration increased markedly. A comparison of the present results has shown that the lactate concentration in the PL is about three times as high as in blood and in CSF. This difference in concentration suggests that the PL lactate is of intracochlear origin and that glycolytic processes take place in the inner ear also under normal conditions. Systematic studies of additional metabolic parameters must be conducted before a definitive physiological interpretation of the present analytical results can be given.

On sources of error in the biochemical study of perilymph (guinea-pig).

Contamination of perilymph with other fluids (cerebrospinal fluid, tissue fluid, blood, endolymph) together with sampling, anaesthesia, surgical intervention or food intake of the animals may considerably affect the analytical result. The numerous possible artefacts seem to be the main reason why varying values are given in the literature for the same chemical component of perilymph. This is also partly true of cerebrospinal fluid and blood. The effect of some sources of error on selected chemical components of perilymph, cerebrospinal fluid and blood is briefly summarized.