Does silvering or 11-ketotestosterone affect osmoregulatory ability in the New Zealand short-finned eel ( Anguilla australis )?

Abstract

Silvering has been associated with advancing osmoregulatory ability. Given the demonstrated role of 11-ketotestosterone (11KT) in mediating many of the silvering-related changes, we investigated the role of 11KT in driving this advanced osmoregulatory ability in the New Zealand short-finned eel (Anguilla australis). Yellow (non-migratory) eels with or without 11KT implants and blank-implanted silver (migratory) eels, either held in freshwater or subjected to seawater challenge, were sampled to determine serum [Na⁺] and [Cl⁻], pituitary prolactin mRNA levels, gill Na⁺/K⁺-ATPase activity and gill mRNA levels for Na⁺/K⁺-ATPase-α1 subunit and for Na⁺/K⁺/2Cl⁻ co-transporter-1α-subunit. Developmental stage and 11KT treatment advanced the eels' osmoregulatory ability. Thus, serum [Na⁺] and [Cl⁻] were affected by developmental stage and 11KT treatment upon seawater challenge. However, seawater challenge, not 11KT treatment or developmental stage, produced the strongest and the most consistent effects on A. australis osmoregulatory processes, inducing significant effects in all the relevant parameters we measured. In light of our results and in view of the eel's marine ancestry, we contend that A. australis, or freshwater eels in general, are highly tolerant and able to adapt quickly to changing salinities even at the yellow stage, which may preclude a critical need for an advanced osmoregulatory ability at silvering.

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Dexmedetomidine preserves the endothelial glycocalyx and improves survival in a rat heatstroke model

Abstract

Purpose

Heatstroke causes systemic inflammation, followed by vascular endothelial damage. The normal vascular endothelium is coated by endothelial glycocalyx (EGCX). Dexmedetomidine (DEX) has an anti-inflammatory effect, but there has been little investigation on the influence of heatstroke on EGCX and the effect of DEX on this condition. Therefore, we examined whether EGCX was disrupted in heatstroke and if DEX improved survival and preserves EGCX.

Methods

Anesthetized Wistar rats were randomly assigned to three groups: a DEX group treated with DEX (5 µg/kg/h) and 0.9% saline infused continuously at 10 ml/kg/h during heat exposure; a NSS group given 0.9% saline during heat exposure; and a SHAM group given 0.9% saline alone without heat exposure. Heatstroke was induced by exposure to an ambient temperature of 40 °C with relative humidity of 60%. The survival rate was assessed up to 2 h after the start of heat exposure. Plasma levels of syndecan-1 and the thickness of EGCX using electron microscopy were measured when the systolic blood pressure fell to less than 80 mmHg.

Results

The survival rate after 2 h of heat exposure was significantly higher in the DEX group compared to the NSS group (89% vs. 22%, P = 0.004). Plasma levels of syndecan-1 were 0.6 ± 1.3, 9.7 ± 5.9, and 2.1 ± 3.4 ng/ml in the SHAM, NSS and DEX groups, respectively (P = 0.013). The thickness of EGCX was significantly higher in the DEX group compared with the NSS group (P = 0.001).

Conclusions

EGCX was disrupted in heatstroke, and DEX improved survival and preserved EGCX.

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Patterns of Hysteresis Between Induction and Emergence of Neuroanesthesia are Present in Spinal and Intracranial Surgeries

Background: Recovery of consciousness is usually seen as a passive process, with emergence from anesthesia depicted as the inverse process of induction resulting from the elimination of anesthetic drugs from their central nervous system sites of action. However, that need not be the case. Recently it has been argued that we might encounter hysteresis to changes in the state of consciousness, known as neural inertia. This phenomenon has been debated in neuroanesthesia, as manipulation of the brain might further influence recovery of consciousness. The present study is aimed at assessing hysteresis between induction and emergence under propofol-opioid neuroanesthesia in humans using estimated propofol concentrations in both spinal and intracranial surgeries. Methods: We identified the moments of loss (LOR) and recovery of responsiveness (ROR) in 21 craniotomies and 25 spinal surgeries. Propofol was given slowly until loss of responsiveness and stopped at the end of surgery. An opioid was present at induction and recovery. Propofol infused was recorded and plasma and effect-site concentrations were estimated using 2 pharmacokinetic models. Dose-response curves were generated. Estimated propofol plasma and effect-site concentrations were compared to assess hysteresis. Results: Estimated propofol concentrations at LOR and ROR showed hysteresis. Whether for spinal or intracranial surgeries, the EC50 of propofol at which half of the patients entered and exited the state of responsiveness was significantly different. Conclusions: Hysteresis was observed between propofol concentrations at LOR and ROR, in both patients presenting for spinal and intracranial surgeries. Manipulation of the brain does not appear to change patterns of hysteresis, suggesting that neural inertia may occur in humans, in a way similar to that found in animal species. These findings justify performing a clinical study in patients using measured propofol concentrations to assess neural inertia. Supported by the Fundação para a Ciência e Tecnologia with the reference projects SFRH/BD/98915/2013 and UID/SEM/50022/2013. The authors have no conflicts of interest to disclose. Address correspondence to: Ana Leitão Ferreira, MSc, MS, Center of Clinical Investigation in Anesthesiology, Service of Anesthesiology, Hospital Center of Porto, Largo Professor Abel Salazar, 4099-001 Porto, Portugal (e-mail: ana.leitao.ferreira@gmail.com). Received April 12, 2018 Accepted September 14, 2018 Copyright © 2018 Wolters Kluwer Health, Inc. All rights reserved

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Journal Club

No abstract available

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The independency of the Bereitschaftspotential from previous stimulus‐locked P3 in visuomotor response tasks

Psychophysiology, EarlyView.


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Cerebral Evoked Potentials in Patients at an Early Stage of Schizophrenia

Visual and auditory EPs (with special attention to their cognitive components) were examined in 33 patients with newly diagnosed schizophrenia (a group of patients, Pat; all subjects obtained supporting pharmacotherapy) and 30 mentally healthy subjects (a control group, Contr). Reversive chess patterns with the squares of 60 or 120 ang. sec were used as stimuli in the case of visual EPs, while tones of different frequencies, 1.0 and 4.0 kHz, were used for initiation of auditory EPs. The odd-ball paradigm was used; the probabilities of significant stimuli (i.e., signals) at each sensory modality were 20 or 50%. The amplitudes and latencies of generally differentiated EP components, with special attention to the P1, N1, P2, N2, P3 (P300), and N4 waves, were measured; in addition, the latencies (times) of sensorimotor reactions (SMRs) to presentation of the signal stimuli (pushing the button) were recorded. The averaged latencies of visual N1, P2, N2, P300, and N4 (at the 50% probability) and of N2, P300, and N4 (20% probability) in patients with schizophrenia were significantly longer than those in the control. Besides, the amplitudes of visual P2 and N2 (50% probability) and of P2, P300, and N4 (20% probability) were significantly lower than in the control. At auditory stimulation, the latencies of nearly all EP components in the Pat group at both 50 and 20% probabilities of significant stimuli were longer that in the norm, but the differences did not reach the significance level. The amplitudes of components P1–N2 in auditory EPs at the 50% probability were significantly lower than in the control. Significantly longer latencies (times) of the SMRs were observed in the Pat group at both auditory and visual stimulation and at both probabilities of significant stimuli. It is concluded that the cognitive deficit in patients with schizophrenia is probably more clearly reflected in the parameters of visual EPs, while changes in the positive symptoms of this disease are more reflected in the parameters of auditory EPs.

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Automated Diagnosis of Encephalopathy Based on Empirical Mode EEG Decomposition

In this study, an empirical mode decomposition (EMD) technique has been applied for EEG signals to identify a neurological disease state qualified as encephalopathy. The EMD technique is an efficient method for decomposing nonstationary and nonlinear signals, which makes it suitable for biosignal processing. This technique generates various components of the signal called intrinsic mode functions (IMFs) whose features are examined for the diagnosis of the disease. We found significant differences between the healthy and patient groups for both statistical and nonlinear parameters of IMFs of the recorded EEGs, which makes those suitable for the diagnosis of encephalopathy. Statistical values, namely minimum, maximum, mean, and standard deviation, and nonlinear parameters, namely approximate entropy and sample entropy of the IMFs, were calculated. Both these features were fed to a Support Vector Machine (SVM) classifier, and their performance parameters were evaluated. It is concluded that statistical parameters, as well as nonlinear parameters of the EEG IMFs, are prospective potential features for automated diagnosis of encephalopathy.

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