Cardiogenic shock etiology and exit strategy impact survival in patients with Impella 5.5

BACKGROUND

Despite historical differences in cardiogenic shock (CS) outcomes by etiology, outcomes by CS etiology have yet to be described in patients supported by temporary mechanical circulatory support (MCS) with Impella 5.5.

OBJECTIVES

This study aims to identify differences in survival and post-support destination for these patients in acute myocardial infarction (AMI) and acute decompensated heart failure (ADHF) CS at a high-volume, tertiary, transplant center.

METHODS

A retrospective review of patients who received Impella 5.5 at our center from November 2020 to June 2022 was conducted.

RESULTS

Sixty-seven patients underwent Impella 5.5 implantation for CS; 23 (34%) for AMI and 44 (66%) for ADHF. AMI patients presented with higher SCAI stage, pre-implant lactate, and rate of prior MCS devices, and fewer days from admission to implantation. Survival was lower for AMI patients at 30 days, 90 days, and discharge. No difference in time to all-cause mortality was found when excluding patients receiving transplant. There was no significant difference in complication rates between groups.

CONCLUSIONS

ADHF-CS patients with Impella 5.5 support have a significantly higher rate of survival than patients with AMI-CS. ADHF patients were successfully bridged to heart transplant more often than AMI patients, contributing to increased survival.

Nationwide variability in the use of induction immunosuppression for adult heart transplantation

BACKGROUND

Institutional factors have been shown to impact outcomes following orthotopic heart transplantation (OHT). This study evaluated center variability in the utilization of induction therapy for OHT and its implications on clinical outcomes.

METHODS

Adult OHT patients between 2010 and 2018 were identified from the United Network for Organ Sharing registry. Transplant centers were stratified based on their rates of induction therapy utilization. Mixed-effects logistic regression models were created with drug-treated rejection within 1 year as primary endpoint and individual centers as a random parameter. Risk-adjusted Cox regression was used to evaluate patient-level mortality outcomes.

RESULTS

In 17,524 OHTs performed at 100 centers, induction therapy was utilized in 48.6% (n = 8411) with substantial variability between centers (interquartile range, 21.4%-79.1%). There were 36, 30, and 34 centers in the low (<29%), intermediate (29%-66%), and high (>67%) induction utilization terciles groups, respectively. Induction therapy did not account for the observed variability in the treated rejection rate at 1 year among centers after adjusting for donor and recipient factors (p = .20). No differences were observed in postoperative outcomes among induction utilization centers groups (all, p > .05). Furthermore, there was a weak correlation between the percentage of induction therapy utilization at the center-level and recipients found to have moderate (r = .03) or high (r = .04) baseline risks for acute rejection at 1 year.

CONCLUSIONS

This analysis demonstrates that there is substantial variability in the use of induction therapy among OHT centers. In addition, there was a minimal correlation with baseline recipient risk or 1-year rejection rates, suggesting a need for better-standardized practices for induction therapy use in OHT.

Outcomes of Adult Heart Transplantation Using Hepatitis C-Positive Donors

Background

This study evaluated the impact of hepatitis C–positive (HCV+) donors on outcomes of heart transplantation in the United States.

Methods and Results

Adults undergoing isolated heart transplantation in the United States between January 1, 2016, and December 31, 2018, were included. The primary outcome was 1‐year post‐transplant survival. Multivariable Cox regression and 2:1 propensity matching were used to compare outcomes between transplants with HCV+ and hepatitis C–negative (HCV−) donors. A subanalysis was performed to evaluate the impact of nucleic acid amplification test positivity on outcomes. Of 7889 isolated heart transplants performed during the study period, 343 (4.4%) used HCV+ donors. Overall unadjusted 1‐year posttransplant survival was not statistically different between HCV− versus HCV+ donors (91.1% versus 90.2%; P=0.86), a finding that persisted after risk adjustment (hazard ratio, 1.05; 95% CI, 0.70–1.58; P=0.80). Propensity matching resulted in 675 well‐balanced patients (437 HCV− and 238 HCV+). Overall 1‐year posttransplant survival was not statistically different in propensity‐matched analysis (89.8% HCV− versus 89.2% HCV+; P=0.88). Rates of 1‐year drug‐treated rejection (21.1% versus 22.1%; P=0.84), postoperative dialysis (11.4% versus 14.7%; P=0.22), and stroke (4.6% versus 2.1%; P=0.10) were also not statistically different between HCV− and HCV+ groups, respectively. Outcomes were not statistically different between nucleic acid amplification test–negative and nucleic acid amplification test–positive HCV+ donors.

Conclusions

Adult heart transplants using HCV+ donors, including those that are nucleic acid amplification test positive, can be performed without an adverse impact on 1‐year survival. Wider implementation of protocols for using HCV+ donors and an assessment of longer‐term outcomes including seroconversion rates will be important in maximizing the effect of HCV+ donors on national donor shortages.

Neighborhood deprivation and depression in adult twins: genetics and gene×environment interaction

BACKGROUND

Depression is a significant problem and it is vital to understand its underlying causes and related policy implications. Neighborhood characteristics are implicated in depression but the nature of this association is unclear. Unobserved or unmeasured factors may confound the relationship. This study addresses confounding in a twin study investigating neighborhood-level effects on depression controlling for genetics, common environment, and gene×environment (G × E) interactions.

METHOD

Data on neighborhood deprivation and depression were gathered from 3155 monozygotic twin pairs and 1275 dizygotic pairs (65.7% female) between 2006 and 2013. The variance for both depression and neighborhood deprivation was decomposed into three components: additive genetic variance (A); shared environmental variance (C); and non-shared environmental variance (E). Depression was then regressed on neighborhood deprivation to test the direct association and whether that association was confounded. We also tested for a G × E interaction in which the heritability of depression was modified by the level of neighborhood deprivation.

RESULTS

Depression and neighborhood deprivation showed evidence of significant A (21.8% and 15.9%, respectively) and C (13.9% and 32.7%, respectively) variance. Depression increased with increasing neighborhood deprivation across all twins (p = 0.009), but this regression was not significant after controlling for A and C variance common to both phenotypes (p = 0.615). The G × E model showed genetic influences on depression increasing with increasing neighborhood deprivation (p < 0.001).

CONCLUSIONS

Neighborhood deprivation is an important contributor to depression via increasing the genetic risk. Modifiable pathways that link neighborhoods to depression have been proposed and should serve as targets for intervention and research.

A phase II trial of high-dose chemotherapy (HDCT) supported by hematopoietic stem-cell transplantation (HSCT) in germ-cell tumors (GCTs) patients failing cisplatin-based chemotherapy: the Multicentric TAXIF II study

BACKGROUND

High-dose chemotherapy (HDCT) is an effective salvage treatment of germ-cell tumors (GCTs) patients. In the first salvage setting, 30%-70% of patients may achieve durable remissions. Even when HDCT is administered as subsequent salvage treatment, up to 20% of patients may still be definitively cured. However, patients with refractory/relapsed disease still have a very poor long-term prognosis, requiring earlier intervention of HDCT.

PATIENTS AND METHODS

This phase II trial was addressed to nonrefractory patients failing Cisplatin-based chemotherapy. Inclusion criteria included seminomatous GCT in relapse after two lines of chemotherapy, nonseminomatous GCT in relapse after first or second lines, partial remission after first line, primary mediastinal GCT in first relapse. Patients received two cycles combining Epirubicin and Paclitaxel (Epi-Tax), followed by three consecutive HDCT, one using a Paclitaxel/Thiotepa (Thio-Tax) association and two using the 5-day Ifosfamide-Carboplatin-Etoposide regimen. The main objective was to determine the complete response rate.

RESULTS

Forty-five patients were included between September 2004 and December 2007: 44 received the first HDCT cycle, 39 two HDCT cycles, 29 could receive the whole protocol. Sixteen patients did not receive the entire protocol, including eight (17.7%) for toxic side-effects. Two patients (4.4%) died of toxicities, and 17 (37.7%) of disease progression. With a median follow-up time of 26 months (range, 4-51), the final overall response rate was 48.8% (including a complete response rate of 15.5% and a partial response/negative serum markers rate of 26.6%) in an intent-to-treat analysis. The median progression-free survival (PFS) and overall survival (OS) times were 22 months [95% confidence interval (CI) 2-not reached] and 32 months (95% CI 4-49), respectively. The 2-year PFS was a plateau setup at 50% (95% CI 32-67) and the 2-year OS was 66% (95% CI 44-81).

CONCLUSION

The TAXIF II protocol was effective in nonrefractory GCT patients failing Cisplatin-based chemotherapy. The toxic death rate remained acceptable in the field of HDCT regimens.

TRIAL REGISTRATION NUMBER

NCT00231582.

[Biological experiments in microgravity: equilibrium function]

The review deals with the investigations of structural and functional modifications in the equilibrium organ (EO) in invertebrates (coelenterates, shells, crustaceans and insects) and vertebrates (fishes, amphibians, rats, primates) on different ontogenetic stages in the condition of microgravity and during readaptation to the Earth's gravity. Results of the investigations detail the adaptive strategy of terrestrial organism in the environment lacking the gravitational components that leads to the discrepancy of an inner model of the body-environment schema constructed by the central nervous system at 1 g and the novel reality. It is manifested by ataxic behavior and increased graviceptors' afferentation against efferent system inactivation. The new condition is defined as a sensibilization phase ensued by the eluding phase: behavior obeys the innate motion strategy, whereas graviceptors' afferentation decreases due to activation of the efferent system. Readaptation to 1 G takes several to 50 days and proceeds as a sequence of slow in motion behavior, ataxia and vestibular sensitization. Reactivity of the gravitosensory system to microgravity was found to be age-dependent. Gain in the EO inertial mass in microgravity and reduction with return to 1 g indicates gravity relevance to EO genesis.

Separate and combined effects of low dose ketamine and nicotine on behavioural and neural correlates of sustained attention

Given the cognitive-promoting properties of the nicotinic acetylcholinergic receptor (nAChR) agonist, nicotine, the increased prevalence of smoke-inhaled nicotine in schizophrenia has been interpreted as an attempt to self-correct cognitive deficits, which have been particularly pronounced in the attentional domain. As glutamatergic abnormalities have been implicated in these attentional deficiencies, this study attempted to shed light on the separate and interactive roles of the N-methyl-d-aspartate receptor (NMDAR) and nAChR systems in the modulation of attention by investigating, in healthy volunteers, the separate and combined effects of nicotine and the NMDAR antagonist ketamine on neural and behavioural responses in a sustained attention task. In a randomized, double-blind, placebo controlled study, performance and the P300 event-related brain potential (ERP) in a visual information processing (RVIP) task were examined in 20 smokers and 20 non-smokers (both male and female). Assessment involved intravenous injection of a low subperceptual bolus dose (.04mg/kg) of ketamine or placebo, which was accompanied by acute treatment with nicotine (4mg) or placebo gum. Nicotine-enhanced attentional processing was most evident in nonsmokers, with both performance accuracy and P300 amplitude measures. Ketamine's detrimental effects on these behavioural and electrophysiologic measures were negatively moderated by acute nicotine, the synergistic effects being expressed differently in smokers and nonsmokers. These findings support the view that acute alterations and individual differences in nAChR function can moderate even subtle glutamatergic-driven cognitive deficiencies in schizophrenia and can be important therapeutic targets for treating cognitive impairments in schizophrenia.

Altered gravity affects ventral root activity during fictive swimming and the static vestibuloocular reflex in young tadpoles (Xenopus laevis)

During early periods of life, modifications of the gravitational environment affect the development of sensory, neuronal and motor systems. The vestibular system exerts significant effects on motor networks that control eye and body posture as well as swimming. The objective of the present study was to study whether altered gravity (AG) affects vestibuloocular and spinal motor systems in a correlated manner. During the French Soyuz taxi flight Andromède to the International Space Station ISS (launch: October 21, 2001; landing: October 31, 2001) Xenopus laevis embryos were exposed for 10 days to microgravity (microg). In addition, a similar experiment with 3g-hypergravity (3g) was performed in the laboratory. At onset of AG, embryos had reached developmental stages 24 to 27. After exposure to AG, each tadpole was tested for its roll-induced vestibuloocular reflex (rVOR) and 3 hours later it was tested for the neuronal activity recorded from the ventral roots (VR) during fictive swimming. During the post-AG recording periods tadpoles had reached developmental stages 45 to 47. It was observed that microgravity affected VR activity during fictive swimming and rVOR. In particular, VR activity changes included a significant decrease of the rostrocaudal delay and a significant increase of episode duration. The rVOR-amplitude was transiently depressed. Hypergravity was less effective on the locomotor pattern; occurring effects on fictive swimming were the opposite of microg effects. As after microgravity, the rVOR was depressed after 3g-exposure. All modifications of the rVOR and VR-activity recovered to normal levels within 4 to 7 days after termination of AG. Significant correlations between the rVOR amplitude and VR activity of respective tadpoles during the recording period have been observed in both tadpoles with or without AG experience. The data are consistent with the assumptions that during this period of life which is characterized by a progressive development of vestibuloocular and vestibulospinal projections (i) microgravity retards the development of VR activity while hypergravity weakly accelerates it; (ii) that microgravity retards the rVOR development while hypergravity caused a sensitization, and that (iii) AG-induced changes of VR activity during fictive swimming have a vestibular origin.

Transketolase-like 1 expression correlates with subtypes of ovarian cancer and the presence of distant metastases

Tumorbiology of ovarian cancer remains unclear. However, it is known that ovarian tumors, especially carcinomas, show elevated expression of glucose membrane transporters for facilitated glucose uptake. It can be assumed that increased glucose uptake leads to higher glucose metabolism. The energy resources of fully malignant transformed carcinomas are mainly supplied by aerobic glycolysis, for which several pathways are known. A key role in aerobic glycolysis is described for the transketolase enzymes. Recently, a novel transketolase-like enzyme called transketolase-like 1 (TKTL1) has been described that links aerobic glycolysis to the synthesis of fatty acids via production of acetyl-CoA. In order to investigate the role of TKTL1 for the progression of ovarian carcinomas, we examined paraffin sections of normal ovarian tissues, ovarian borderline tumors, and mucinous or serous papillary ovarian adenocarcinomas with respect to their expression of TKTL1. We identified a significantly elevated expression of TKTL1 in serous papillary ovarian adenocarcinomas, which correlates with poor prognostic parameters in the examined study group. Therefore, it can be assumed that TKTL1 plays a crucial role in ovarian cancer metabolism and that its expression predicts poor prognosis. Further investigations should be performed in order to evaluate whether this new enzyme is important for ovarian cancer tumorbiology and to analyze the potential role of TKTL1 as new target for specific antitumoral therapy.

Morphometric investigations of sensory vestibular structures in tadpoles (Xenopus laevis) after a spaceflight: implications for microgravity-induced alterations of the vestibuloocular reflex

In lower vertebrates, gravity deprivation by orbital flights modifies the vestibuloocular reflex. Using the amphibian Xenopus laevis, the experiments should clarify to which extent macular structures of the labyrinth are responsible for these modifications. In particular, the shape of otoconia and number and size of sensory macular cells expressing CalBindin were considered. CalBindin is common in mature sensory cells including vestibular hair cells and is probably involved in otoconia formation. Two developmental stages were used for this study: stage 26/27 embryos, which were unable to perform the roll-induced vestibuloocular reflex (rVOR) at onset of microgravity, and stage 45 tadpoles, which had already developed the reflex. The main observations were that the developmental progress of the animals was not affected by microgravity; that in the young tadpole group with normal body shape the rVOR was not modified by microgravity, while in the older group with microgravity experience, the rVOR was augmented; and that significant effects on the shape of otoconia and on the number and size of CalBindin-expressing cells of the labyrinthine maculae cells were absent. In addition, behavioural data were never significantly correlated with morphological features of macular structures such as size and number of CalBindin-expressing cells. It is postulated that mechanisms of vestibular adaptation to microgravity during early development are probably based on mechanisms located in central structures of the vestibular system.

Nicotine and smoker status moderate brain electric and mood activation induced by ketamine, an N-methyl-d-aspartate (NMDA) receptor antagonist

As the increased smoking prevalence in schizophrenics may be interpreted as an adaptive response to an underlying biological defect, investigations into nicotine's actions within N-methyl-d-aspartate (NMDA) antagonist drug models of schizophrenia may improve our understanding of the role of glutamatergic neurotransmission in initiating and maintaining nicotine dependence in this disorder. In this double-blind, placebo-controlled, randomized study, the electroencephalographic (EEG) and subjective response to a sub-psychotomimetic intravenous dose of the NMDA antagonist ketamine was examined in 20 regular smokers and 20 non-smokers pretreated with placebo or nicotine gum. Although nicotine increased EEG arousal, ketamine produced electrocerebral signs of brain activation (decreased slow wave power) and sedation (decreased fast wave power and frequency), which were not affected by nicotine pretreatment and were evident only in non-smokers. Ketamine increased a number of self-report indices of subjective arousal, some of which were attenuated and potentiated by nicotine in smokers and non-smokers, respectively. These findings suggest that long-term (evidenced by smoker vs. non-smoker comparisons) and short-term (acute) nicotine exposure may alter NMDA receptor-mediated arousal and mood systems in a way that promotes nicotine dependence in smokers, and addresses neurobiological deficiencies in smokers with schizophrenia.

Crystal structure of μ3-chloro-μ3-hydroxo-tris(μ-chloro)tris(tetramethylethylenediamine) trinickel(II) iodide, [Ni3(C6H16N2)3Cl4(OH)]I

C18H49Cl4IN6Ni3O, monoclinic, C12/c1 (no. 15), a = 33.562(7) Å, b = 12.220(2) Å, c = 18.849(4) Å, β = 117.70(3)°, V = 6844.7 Å3, Z = 8, Rgt(F) = 0.059, wRref(F) = 0.066, T = 273 K.

The critical care clinical pharmacist: evolution of an essential team member

OBJECTIVE

To review the history, training requirements, contributions to patient care outcomes, and workforce issues of critical care pharmacists.

DATA SOURCE AND SELECTION

Literature obtained through Medline search with manual cross-referencing.

DATA EXTRACTION AND SYNTHESIS

Original and selected review articles and guideline documents were reviewed for references to critical care pharmacists and their role on the multiprofessional critical care team.

CONCLUSIONS

Critical care pharmacists are recognized as essential members of the critical care team as a result of contributions to medication safety, improved patient outcomes, and reduced drug costs and as a source of drug information and provider of education. A growing number of pharmacists practice in critical care. Additional opportunities exist and can be met if an adequate supply of trained specialists can be developed.

The 6-min walk test (6MW) as an efficacy endpoint in pulmonary arterial hypertension clinical trials: Demonstration of a ceiling effect

BACKGROUND

PAH trials traditionally use 6MW as the primary endpoint. Concerns regarding a "ceiling effect" masking efficacy have led to exclusion of patients with milder disease from most trials (BL 6MW>450 m). STRIDE I evaluated the selective endothelin A receptor antagonist, sitaxsentan (SITAX), in a 12-week randomized, double-blind, trial (178 patients) employing placebo (PBO), 100 mg or 300 mg SITAX orally once daily in PAH and included patients with NYHA class II, congenital heart disease and a BL 6MW>450 m, groups often excluded from previous trials.

METHODS

We analyzed 6MW effects For All Pts (intention-to treat) and those meeting Traditional enrollment criteria, defined as patients with NYHA class III or IV and 6MW< or =450 m at BL with idiopathic PAH or PAH related to connective tissue disease. The 100 mg and 300 mg SITAX arms are pooled based on similar treatment effects on 6MW.

CONCLUSION

Existence of a "ceiling effect" is supported by these data. The magnitude of the treatment effect and statistical power when using 6MW as the endpoint. Comparisons between PAH trials that do not adjust for the effects of differing enrollment criteria require caution.

Number needed to treat and cost of recombinant human erythropoietin to avoid one transfusion-related adverse event in critically ill patients

OBJECTIVE

To calculate the absolute risk reduction of transfusion-related adverse events, the number of patients needed to treat, and cost to avoid one transfusion-related adverse event by using erythropoietin in critically ill patients

DESIGN

Number needed to treat with sensitivity analysis.

SETTING

Teaching hospital.

PATIENTS

Hypothetical cohort of critically ill patients who were candidates to receive erythropoietin.

INTERVENTIONS

Using vs. not using erythropoietin to reduce the need for packed red blood cell transfusions.

MEASUREMENTS AND MAIN RESULTS

We used published estimates of known transfusion risks: transfusion-related acute lung injury, transfusion-related errors, hepatitis B and C, human immunodeficiency virus, human T-cell lymphotropic virus, and bacterial contamination, stratified by severity. Based on the estimated risk and frequency of transfusions with and without erythropoietin, we calculated the absolute risk reduction of transfusion-related adverse events, the number needed to treat, and cost to avoid one transfusion-related adverse event by using erythropoietin. The estimated incidence of transfusion-related adverse event was 318 permillion units transfused for all transfusion-related adverse events, 58 per million for serious transfusion-related adverse events, and 21 per million for likely fatal transfusion-related adverse events. The routine use of erythropoietin resulted in an absolute risk reduction of 191 per million for all transfusion-related adverse events, 35 per million for serious transfusion-related adverse events, and 12 per million for likely fatal transfusion-related adverse events. The number needed to treat was 5,246 to avoid one transfusion-related adverse event, 28,785 to avoid a serious transfusion-related adverse event, and 81,000 for a likely fatal transfusion-related adverse event. The total cost was $4,700,000 to avoid one transfusion-related adverse event, $25,600,000 to avoid one serious transfusion-related adverse event, and $71,800,000 to avoid a likely fatal transfusion-related adverse event. The magnitude of these results withstood extensive sensitivity analysis.

CONCLUSIONS

From the perspective of avoidance of adverse events, erythropoietin does not appear to be an efficient use of limited resources for routine use in critically ill patients.

Pharmacology and pharmacokinetics of sedatives and analgesics

The agents used for sedation and analgesia during endoscopy have complex pharmacokinetic and pharmacodynamic properties. Knowledge of these characteristics is necessary for determining the proper agent and dose for specific patient needs. Short-acting agents, such as fentanyl, midazolam, and propofol, provide rapid sedation with a short duration of action that allows patients to return to normal functioning rapidly. When designing a dosing regimen with these agents, age and organ (liver, kidney) function of patients and concomitant medications that may interfere with metabolic and elimination pathways must be considered.

Crickets in space: morphological, physiological and behavioral alterations induced by space flight and hypergravity

"Crickets in Space" was a Neurolab experiment by which the balance between genetic programs and the gravitational environment for the development of a gravity sensitive neuronal system was studied. The model character of crickets was justified by their external gravity receptors, identified position-sensitive interneurons (PSI) and gravity-related compensatory head response, and by the specific relation of this behavior to neuronal arousal systems activated by locomotion. These advantages allowed to study the impact of modified gravity on cellular processes in a complex organism. Eggs, 1st, 4th and 6th stage larvae of Acheta domesticus were used. Post-flight experiments revealed a low susceptibility of the behavior to micro- and hypergravity while the physiology of the PSI was significantly affected. Immunocytological investigations revealed a stage-dependent sensitivity of thoracic GABAergic motoneurons to 3 g-conditions concerning their soma sizes but not their topographical arrangement. The morphology of neuromuscular junctions was not affected by 3 g-hypergravity. Peptidergic neurons from cerebral sensorimotor centers revealed no significant modifications by microgravity (micro g). The contrary physiological and behavioral results indicate a facilitation of 1 g-readaptation originating from accessory gravity, proprioceptive and visual sense organs. Absence of anatomical modifications point to an effective time window of micro g or 3 g-expo-sure related to the period of neuronal proliferation. The analysis of basic mechanisms of how animals and man adapt to altered gravitational conditions will profit from a continuation of the project "Crickets in Space".

Time courses of aspartate and glutamate concentrations in the focus area during penicillin induced epileptiform activity in awake rats

1. In 16 awake rats, the time courses of cortical aspartate (ASP) and glutamate (GLU) concentrations were investigated before, during and after penicillin-induced epileptiform activity (PCN-EA). The amino acids were collected by means of the microdialysis technique from a site within the motor cortex located close to the PCN focus. PCN-EA was recorded by means of 12 cortical electrodes. 2. The median time courses of ASP and GLU concentrations demonstrated no relation to the time course of PCN-EA. In contrast, the analysis of individual time courses revealed three response types for both ASP and GLU which could not be related to specific sites within the motor cortex. 3. The ASP concentration was i) not affected by epileptiform activity (8 of 16 rats), ii) changed synchronously with the PCN-EA (3 of 16), or iii) increased transiently or in a long-lasting manner during or after disappearance of PCN-EA (5 of 16). 4. The GLU concentration was i) not effected or only slightly affected by epileptiform activity (5 of 16), ii) decreased strongly during the activity (7 of 16), or iii) increased during the epileptiform activity (4 of 16). 5. If all rats were taken into account, the overall observation was absence of a uniform correlation type between the time courses of ASP and GLU concentrations; i.e. epileptiform activity affects the time courses of ASP and GLU concentrations in an independent manner. 6. These results demonstrate that consideration of median values alone can mask significant effects of epileptiform activity on the biochemistry of the brain in individual animals. The study also shows that a consideration of individual time courses of physiological and biochemical parameters is mandatory for the understanding of basic mechanisms of epilepsy. The results support the hypothesis about the activation of neuroprotective mechanisms by epileptiform activity.

Adaptation of the macular vestibuloocular reflex to altered gravitational conditions in a fish (Oreochromis mossambicus)

Young fish (Oreochromis mossambicus) were exposed to microgravity (micro g) for 9 to 10 days, or to hypergravity (hg) for 9 days. For several weeks after termination of micro g and hg, the roll-induced static vestibuloocular reflex (rVOR) was recorded. In stage 11/12-fish, the rVOR amplitude (angle between the maximal up and down movement of an eye during a complete 360 degree lateral roll) of micro g-animals increased significantly by 25% compared to 1 g-controls during the first post-flight week but decreased to the control level during the second post-flight week. Microgravity had no effect in stage 14/16 fish on the rVOR amplitude. After 3 g-exposure, the rVOR amplitude was significantly reduced for both groups compared to their 1 g-controls. Readaptation to 1 g-condition was completed during the second post-3 g week. We postulate a critical period during which the development of the macular vestibuloocular reflex depends on gravitational input, and which is limited by the first appearance of the rVOR. At this period of early development, exposure to microgravity sensitizes the vestibular system while hypergravity desensitizes it.