Cisternal and intraventricular irrigation in subarachnoid and intraventricular haemorrhage.

BACKGROUND: Subarachnoid haemorrhage (SAH) and intraventricular haemorrhage (IVH) are associated with poor patient outcomes. Intraventricular fibrinolysis is effective in clearing IVH and improving patient survival and neurological outcome. By similar rationale, cisternal irrigation has been proposed as a potential method to accelerate haematoma clearance in SAH. We aimed to provide a comprehensive review and meta-analysis evaluating the effect of intraventricular and cisternal irrigation on clinical outcomes in patients with SAH and IVH. METHODS: The Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines were followed preparing this systematic review and study selection was performed by multiple investigators. We extracted ORs from the individual studies and aggregated these using a random effects model. The quality of evidence was evaluated using Grading of Recommendations, Assessment, Development and Evaluations assessment and ROBINS-I or RoB-2. RESULTS: 24 articles were included. In SAH, we found that cisternal irrigation with fibrinolytic agents was associated with reduced mortality (OR: 0.68, 95% CI 0.46 to 1.00), higher probability of favourable functional outcome (OR: 1.80, 95% CI 1.30 to 2.51), and reduced risks of DCI (OR: 0.28, 95% CI 0.18 to 0.42) and cerebral vasospasm (OR: 0.28, 95% CI 0.18 to 0.42), compared with conventional therapy. Cisternal irrigation with vasodilatory agents was associated with lower mortality (OR: 0.32, 95% CI 0.13 to 0.79) and reduced risk of cerebral vasospasm (OR: 0.37, 95% CI 0.17 to 0.79). The evidence for irrigation therapy of IVH was sparse and insufficient to show any significant effect. CONCLUSION: In this study, we found that cisternal irrigation could improve the prognosis in patients with SAH compared with conventional therapy. There is no evidence to support cisternal irrigation treatment of IVH.

Reliability and performance of the IRRAflow® system for intracranial lavage and evacuation of hematomas-A technical note.

BACKGROUND: Intraventricular hemorrhage (IVH) is a severe condition with poor outcomes and high mortality. IRRAflow® (IRRAS AB) is a new technology introduced to accelerate IVH clearance by minimally invasive wash-out. The IRRAflow® system performs active and controlled intracranial irrigation and aspiration with physiological saline, while simultaneously monitoring and maintaining a stable intracranial pressure (ICP). We addressed important aspects of the device implementation and intracranial lavage. METHOD: To allow versatile investigation of multiple device parameters, we designed an ex vivo lab setup. We evaluated 1) compatibility between the IRRAflow® catheter and the Silverline f10 bolt (Spiegelberg), 2) the physiological and hydrodynamic effects of varying the IRRAflow® settings, 3) the accuracy of the IRRAflow® injection volumes, and 4) the reliability of the internal ICP monitor of the IRRAflow®. RESULTS: The IRRAflow® catheter was not compatible with Silverline bolt fixation, which was associated with leakage and obstruction. Design space exploration of IRRAflow® settings revealed that appropriate settings included irrigation rate 20 ml/h with a drainage bag height at 0 cm, irrigation rate 90 ml/h with a drainage bag height at 19 cm and irrigation rate 180 ml/h with a drainage bag height at 29 cm. We found the injection volume performed by the IRRAflow® to be stable and reliable, while the internal ICP monitor was compromised in several ways. We observed a significant mean drift difference of 3.16 mmHg (variance 0.4, p = 0.05) over a 24-hour test period with a mean 24-hour drift of 3.66 mmHg (variance 0.28) in the pressures measured by the IRRAflow® compared to 0.5 mmHg (variance 1.12) in the Raumedic measured pressures. CONCLUSION: Bolting of the IRRAflow® catheter using the Medtronic Silverline® bolt is not recommendable. Increased irrigation rates are recommendable followed by a decrease in drainage bag level. ICP measurement using the IRRAflow® device was unreliable and should be accompanied by a control ICP monitor device in clinical settings.

A 72-h sedated porcine model of traumatic spinal cord injury.

Introduction: There is an increasing focus on the prevention of secondary injuries following traumatic spinal cord injury (TSCI), especially through improvement of spinal cord perfusion and immunological modulation. Such therapeutic strategies require translational and controlled animal models of disease progression of the acute phases of human TSCI. Research question: Is it possible to establish a 72-h sedated porcine model of incomplete thoracic TSCI, enabling controlled use of continuous, invasive, and non-invasive modalities during the entire sub-acute phase of TSCI? Material and methods: A sham-controlled trial was conducted to establish the model, and 10 animals were assigned to either sham or TSCI. All animals underwent a laminectomy, and animals in the TSCI group were subjected to a weight-drop injury. Animals were then kept sedated for 72 h. The amount of injury was assessed by ex-vivo measures MRI-based fiber tractography, histology and immunohistochemistry. Results: In all animals, we were successful in maintaining sedation for 72 h without comprising vital physiological parameters. The MRI-based fiber tractography showed that all TSCI animals revealed a break in the integrity of spinal neurons, whereas histology demonstrated no transversal sections of the spine with complete injury. Notably, some animals displayed signs of secondary ischemic tissue in the cranial and caudal sections. Discussion and conclusions: This study succeeded in producing a porcine model of incomplete TSCI, which was physiologically stable up to 72 h. We believe that this TSCI model will constitute a potential translational model to study the pathophysiology secondary to TSCI in humans.

Descriptive registry study on outcome and complications of external ventricular drainage treatment of intraventricular haemorrhage in a Danish cohort: a study protocol.

INTRODUCTION: Intraventricular haemorrhage (IVH) is associated with high morbidity and mortality. External ventricular drainage (EVD) has been shown to decrease mortality. Although EVD is widely used, outcome and complication rates in EVD-treated patients with IVH are not fully elucidated. This study aims to describe EVD complication rates and outcomes in patients with primary and secondary IVH at two university hospitals in Denmark. The study will provide a historical reference of relevant endpoints for use in future clinical trials involving patients with IVH. METHODS AND ANALYSIS: This descriptive, multicentre registry study included adult patients (age 18+) with primary or secondary IVH and treated with at least one EVD between 2017 and 2021 at Aarhus University Hospital or Odense University Hospital. Patients are identified using the Danish National Patient Register. Data are collected and recorded from patient medical records. Relevant descriptive statistics and correlation analyses will be applied. ETHICS AND DISSEMINATION: Ethical approval and authorisation to access, store and analyse data have been obtained (Central Denmark Region Committee on Health Research Ethics). The research lead will present the results of the study. Data will be reported according to the Strengthening the Reporting of Observational Studies in Epidemiology and results submitted for publication in peer-reviewed journals.

Intraventricular Lavage vs External Ventricular Drainage for Intraventricular Hemorrhage: A Randomized Clinical Trial.

Importance: Intraventricular lavage has been proposed as a minimally invasive method to evacuate intraventricular hemorrhage. There is little evidence to support its use. Objective: To evaluate the safety and potential efficacy of intraventricular lavage treatment of intraventricular hemorrhage. Design, Setting, and Participants: This single-blinded, controlled, investigator-initiated 1:1 randomized clinical trial was conducted at Aarhus University Hospital and Odense University Hospital in Denmark from January 13, 2022, to November 24, 2022. Follow-up duration was 90 days. The trial was set to include 58 patients with intraventricular hemorrhage. Prespecified interim analysis was performed for the first 20 participants. Data were analyzed from February to April 2023. Interventions: Participants were randomized to receive either intraventricular lavage or standard drainage. Main Outcomes and Measures: The main outcome was risk of catheter occlusions. Additional safety outcomes were catheter-related infections and procedure time, length of stay at the intensive care unit, duration of treatment, and 30-day mortality. The main outcome of the prespecified interim analysis was risk of severe adverse events. Efficacy outcomes were hematoma clearance, functional outcome, overall survival, and shunt dependency. Results: A total of 21 participants (median [IQR] age, 67 [59-82] years; 14 [66%] male) were enrolled, with 11 participants randomized to intraventricular lavage and 10 participants randomized to standard drainage; 20 participants (95%) had secondary intraventricular hemorrhage. The median (IQR) Graeb score was 9 (5-11), and the median (IQR) Glasgow Coma Scale score was 6.5 (4-8). The study was terminated early due to a significantly increased risk of severe adverse events associated with intraventricular lavage at interim analysis (risk difference for control vs intervention, 0.43; 95% CI, 0.06-0.81; P = .04; incidence rate ratio for control vs intervention, 6.0; 95% CI, 1.38-26.1; P = .01). The rate of catheter occlusion was higher for intraventricular lavage compared with drainage (6 of 16 patients [38%] vs 2 of 13 patients [7%]; hazard ratio, 4.4 [95% CI, 0.6-31.2]; P = .14), which met the prespecified α = .20 level. Median (IQR) procedure time for catheter placement was 53.5 (33-75) minutes for intraventricular lavage vs 12 (4-20) minutes for control (P < .001). Conclusions and Relevance: This randomized clinical trial of intraventricular lavage vs standard drainage found that intraventricular lavage was encumbered with a significantly increased number of severe adverse events. Caution is recommended when using the device to ensure patient safety. Trial Registration: ClinicalTrials.gov Identifier: NCT05204849.

Glial fibrillary acidic protein is a robust biomarker in cerebrospinal fluid and peripheral blood after traumatic spinal cord injury: a prospective pilot study.

PURPOSE: Biochemical biomarkers to determine the injury severity and the potential for functional recovery of traumatic spinal cord injury (TSCI) are highly warranted; however, it remains to be clarified whether cerebrospinal fluid (CSF) or peripheral blood (PB) is the ideal sample media. This study aims to measure and compare biomarker concentrations in CSF and PB and to explore associations between biomarker concentrations and injury severity, i.e., American Spinal Injury Association (ASIA) Impairment Scale (AIS) grade, and biomarker concentrations and clinical outcome, i.e., AIS grade improvement and Spinal Cord Independent Measure version III (SCIM-III) score. METHODS: From 2018 to 2020, we conducted a single-center prospective pilot study of TSCI patients (n=15) and healthy controls (n=15). Sample collection and clinical outcome assessment were performed at median 13 h [IQR: 19], 9 days [IQR: 2], and 148 days [IQR: 49] after TSCI. Concentrations of neuron-specific enolase (NSE); glial fibrillary acid protein (GFAP); neurofilament light chain (NfL); interferon-γ (IFN-γ); interleukin (IL)-1ß, IL-2, IL-4, IL-6, IL-8, IL-10, IL-12p70, and IL-13; and tumor necrosis factor α (TNF-α) were measured and associated to clinical outcomes. RESULTS: The biomarker concentrations were higher in CSF than PB. CSF concentrations of GFAP, NSE, IFN-y, TNF-a, IL-2, IL-12p70, IL-4, IL-10, and IL-13 and PB concentrations of GFAP and IFN-y were significantly associated with AIS grade, but not with AIS grade improvement or SCIM-III score. CONCLUSIONS: Our results support GFAP as a potential diagnostic biomarker that may be measured in CSF as well as PB.

Treatment of Intraventricular Hemorrhage with External Ventricular Drainage and Fibrinolysis: A Comprehensive Systematic Review and Meta-Analysis of Complications and Outcome.

BACKGROUND: External ventricular drainage (EVD) is a key factor in the treatment of intraventricular hemorrhage (IVH) but associated with risks and complications. Intraventricular fibrinolysis (IVF) has been proposed to improve clinical outcome and reduce complications of EVD treatment. The following review and metaanalysis provides a comprehensive evaluation of IVH treatment with external ventricular drainage (EVD) and intraventricular fibrinolysis (IVF) with regards to complications and clinical outcomes. METHODS: The PRISMA guidelines were followed preparing this review. Studies included in the meta-analysis were compared using forest plots and the related odds ratios. RESULTS: After a literature search, 980 articles were identified and 65 and underwent full-text review. Forty-two articles were included in the review and meta-analysis. We found that bolted and antibiotic-coated catheters were superior to tunnelled/uncoated catheters (P < 0.001) and antibiotic- vs. silver-impregnated catheters (P < 0.001]) in preventing infection. Shunt dependency was related to the volume of blood in the ventricles but unaffected by IVF (P = 0.98). IVF promoted hematoma clearance, decreased mortality (22.4% vs. 40.9% with IVF vs. no IVF, respectively, P < 0.00001), improved good functional outcomes (47.2% [IVF] vs. 38.3% [no IVF], P = 0.03), and reduced the rate of catheter occlusion from 37.3% without IVF to 10.6% with IVF (P = 0.0003). CONCLUSIONS: We present evidence and best practice recommendations for the treatment of IVH with EVD and intraventricular fibrinolysis. Our analysis further provides a comprehensive quantitative reference of the most relevant clinical endpoints for future studies on novel IVH technologies and treatments.

Study protocol for ACTIVE study: safety and feasibility evaluation of external ventricular drainage with ACTIVE fluid exchange in intraventricular hemorrhage-a phase 2, multi-center, randomized controlled trial.

BACKGROUND: Primary intraventricular hemorrhage (IVH) or IVH secondary to intracerebral (ICH) and subarachnoid hemorrhage (SAH) are known to have a very poor prognosis, with an expected mortality between 50 and 80% (Hinson et al. Current Neurology and Neuroscience Reports 10:73-82, 2010). Clearance of IVH might improve patient outcome. METHODS: The study is designed as an investigator-initiated, comparative, prospective, multi-center, 1:1 randomized phase 2 trial evaluating the efficacy and safety of active irrigation in external ventricular drainage (intervention arm-IRRAflow) compared to passive external ventricular drainage (control arm-EVD). The trial will enroll 58 patients with primary or secondary IVH. Major eligibility criteria include age ≥18 years of age, IVH documented on head CT or MRI scan (Graeb score ≥3), need of cerebrospinal fluid drainage, deterioration of consciousness or medical sedation at the time of enrollment, and indication for active treatment evaluated by the treating physicians. Exclusion criteria included patients with fixed and dilated pupils and pregnant or nursing women. The primary endpoint of the study is catheter occlusion evaluated by time to first observed occlusion from VC placement. Secondary endpoints include clearance of ventricular blood as measured by head CT scan, rates of catheter-related infection and shunt dependency, length of intensive care unit stay, functional status-Extended Glascow Outcome Scale (eGOS) and modified Rankin scale (mRS) at discharge to rehabilitation and 90 days-and mortality rates at 30 days and 90 days. DISCUSSION: With no standardized treatment for IVH and a poor prognosis, new treatments are needed. IVH patients often need CSF drainage to treat hydrocephalus and to decrease ICP. Standard treatment with passive external ventricular drainage is related to an increased risk of infections which is found in up to 22% of treated cases. The passive VC is known to have a risk of occlusion and is seen in 19-47% of the cases. We hypothesize that the use of active fluid change using the IRRAflow system will be safe and feasible and will reduce the occlusion and infection rates in patients with IVH. TRIAL REGISTRATION: ClicalTrials.gov NCT05204849. Registered 15 December 2021. Updated 24 January 2022.

Cerebrospinal fluid and peripheral blood proteomics in Traumatic Spinal Cord Injury: A prospective pilot study.

•Proteomics enable profiling of inflammatory responses after spinal cord injury.•Proteins are differentially expressed over time.•Proteins are differentially expressed in cerebrospinal fluid and peripheral blood.•A poor relationship exists between protein expression and neurological outcome.

The inflammatory response and blood-spinal cord barrier integrity in traumatic spinal cord injury: a prospective pilot study.

PURPOSE: Triggering of inflammatory responses and disruption of blood-spinal cord barrier (BSCB) integrity are considered pivotal events in the pathophysiology of traumatic spinal cord injury (TSCI). Yet, these events are poorly understood and described in humans. This study aims to describe inflammatory responses and BSCB integrity in human TSCI. METHODS: Fifteen TSCI patients and fifteen non-TSCI patients were prospectively recruited from Aarhus University Hospital, Denmark. Peripheral blood (PB) and cerebrospinal fluid (CSF) were collected at median day 0 [IQR: 1], median day 9 [IQR: 2], and median day 148 [IQR: 49] after injury. PB and CSF were analyzed for immune cells by flow cytometry, cytokines by multiplex immunoassay, and BSCB integrity by IgG Index. RESULTS: Eleven TSCI patients completed follow-up. Results showed alterations in innate and adaptive immune cell counts over time. TSCI patients had significantly increased cytokine concentrations in CSF at the first and second follow-up, while only concentrations of interleukin (IL)-4, IL-8, and tumor necrosis factor-α remained significantly increased at the third follow-up. In PB, TSCI patients had significantly increased IL-6, IL-8, and IL-10 concentrations and significantly decreased interferon-γ concentrations at the first follow-up. Results further showed increased IgG Index indicative of BSCB disruption in seven TSCI patients at the first follow-up, five TSCI patients at the second follow-up, and two patients at the third follow-up. CONCLUSIONS: Our results suggest that TSCI mainly triggers innate inflammatory responses that resolves over time, although with some degree of non-resolving inflammation, particularly in CSF. Our results cannot confirm BSCB disruption in all TSCI patients.

Diffusional kurtosis imaging as a possible prognostic marker of cervical incomplete spinal cord injury outcome: a prospective pilot study.

BACKGROUND: Spinal cord injury (SCI) is associated with substantial chronic morbidity and mortality. Routine imaging techniques such as T1- and T2-weighted magnetic resonance imaging (MRI) are not effective in predicting neurological deficiency grade or outcome. Diffusional kurtosis imaging (DKI) is an MR imaging technique that provides microstructural information about biological tissue. There are no longitudinal prospective studies assessing DKI metrics in acute traumatic SCI. Therefore, the purpose of this study was to establish a DKI protocol for acute SCI and correlate the DKI metrics to the functional neurological outcome of the patients. METHODS: Eight consecutive SCI patients referred to our institution with cervical SCI were included in the study. An acute diagnostic MRI scan was supplemented with a novel fast, mean kurtosis DKI protocol, which describes the average deviation from Gaussian diffusional along nine different directions. Mean kurtosis values were measured at the injury site and normalized to the mean kurtosis values of a non-injured site. At discharge form specialized rehabilitation, patients were evaluated using the Spinal Cord Independence Measure-III (SCIM-III). The DKI metrics and SCIM-III were analysed using Spearman's rank correlation. RESULTS: This pilot study found a significant correlation between decreasing mean kurtosis values at the injury site of the spinal cord and higher grade of disability measured by the SCIM-III (p = 0.002). CONCLUSION: This pilot study found that DKI may be a valuable tool as a prognostic marker in the acute phase of SCI.

Vagus Nerve Cross-Sectional Area in Patients With Parkinson's Disease-An Ultrasound Case-Control Study.

Background: Vagal parasympathetic neurons are prone to degeneration in Parkinson's disease (PD). High-resolution ultrasound can precisely estimate the cross-sectional (CSA) area of peripheral nerves. Here, we tested the hypothesis that vagus CSA is reduced in PD. Methods: We included 56 healthy controls (HCs) and 63 patients with PD. Using a high-end ultrasound system equipped with a high-frequency transducer, five images were obtained of each nerve. The hypoechoic neuronal tissue was delineated offline with dedicated software and the CSA extracted. Results: In the initial PD vs. HC comparison, no statistically significant differences were observed in mean left vagus CSA (HC: 1.97 mm2, PD: 1.89 mm2, P = 0.36) nor in mean right vagus CSA (HC: 2.37 mm2, PD: 2.23 mm2, P = 0.17). The right vagus CSA was significantly larger than the left vagus CSA in both groups (P < 0.0001). Females were overrepresented in the HC group and presented with generally smaller vagus CSAs. Consequently, sex-adjusted CSA was significantly smaller for the right vagus nerve of the PD group (P = 0.041), but not for the left. Conclusion: A small but significant reduction in sex-adjusted right vagus CSA was observed in patients with PD. The left vagus CSA was not significantly reduced in patients with PD. Ultrasound may not be a suitable method to detecting vagal axonal loss in individual patients.

Fatal 3-Nitropropionic Acid Poisoning after Consuming Coconut Water.

We describe the fatal course of a patient with initial symptoms of vomiting and nausea who developed symptoms of dystonia, encephalopathy, and coma. The cause of death was poisoning with 3-nitropropionic acid from coconut water spoiled with the fungus Arthrinium saccharicola. We present the clinical findings and forensic analysis.

Initial blood pressure is important for long-term outcome after traumatic spinal cord injury.

OBJECTIVE: Patients with traumatic spinal cord injury (TSCI) are at risk of developing neurogenic shock that causes hypotension and thereby secondary injury to the spinal cord due to ischemia. Hemodynamic treatment of patients with acute TSCI remains inadequately elucidated. Guidelines for management are divergent and based on limited evidence. To this end, the authors evaluated whether mean arterial blood pressure (MABP) during the prehospital and initial hospital phases of TSCI treatment is correlated with long-term neurological outcome. METHODS: The authors performed a retrospective cohort study based on a chart review of MABP data collected during the prehospital transport, in the operating room (OR), and in the neurointensive care unit (NICU) during the first 7 days after trauma. Data from the NICU were divided into two periods: days 1-2 and days 3-7. Data were analyzed using Spearman's rank correlation to evaluate for any correlation between MABP and changes in the International Standards for Neurological Classification of Spinal Cord Injury (ISNCSCI) score 1 year postinjury. In the analysis, the MABP target value was 80 mm Hg. Hypotension was treated with metaoxedrin or norepinephrine. Statistically significant differences were evaluated using Spearman's rank correlation coefficient. RESULTS: The chart review yielded 129 patients treated for TSCI. The inclusion period was 2010-2017. For the prehospital transport measurements of MABP, the Spearman's rank correlation coefficient was a rho of 0.5662 (p < 0.001), for OR measurements it was a rho of 0.6818 (p < 0.001), and for the NICU measurements it was a rho of 0.4611 (p < 0.001); for NICU unit days 1-2 and days 3-7, the Spearman's rank correlation coefficient was a rho of 0.2209 (p = 0.0681). CONCLUSIONS: Continuous MABP levels exceeding 80 mm Hg have a significant impact on neurological outcome-from earliest possible stabilization in the prehospital care, through hospital admission, the surgical phase, and into the first 2 days in the NICU.

Best practice guidelines for blunt cerebrovascular injury (BCVI).

Blunt cerebrovascular injury (BCVI) is a non-penetrating injury to the carotid and/or vertebral artery that may cause stroke in trauma patients. Historically BCVI has been considered rare but more recent publications indicate an overall incidence of 1-2% in the in-hospital trauma population and as high as 9% in patients with severe head injury. The indications for screening, treatment and follow-up of these patients have been controversial for years with few clear recommendations. In an attempt to provide a clinically oriented guideline for the handling of BCVI patients a working committee was created. The current guideline is the end result of this committees work. It is based on a systematic literature search and critical review of all available publications in addition to a standardized consensus process. We recommend using the expanded Denver screening criteria and CT angiography (CTA) for the detection of BCVI. Early antithrombotic treatment should be commenced as soon as considered safe and continued for at least 3 months. A CTA at 7 days to confirm or discard the diagnosis as well as a final imaging control at 3 months should be performed.

[Assessment of the prognosis in patients who remain comatose after resuscitation from cardiac arrest]. / Vurdering af prognose hos patienter med manglende opvågning efter hjertestop

In Denmark there are around 3,500 unexpected cardiac arrests (CA) out of hospital each year. There is an unknown number of CA in hospitals. The survival rate after CA outside a hospital in Denmark is 10% after 30 days. There are varying data for the neurological outcome in this group of patients. The purpose of this work is to disseminate new knowledge and to help standardizing the treatment in the group of patients who remain comatose after being resuscitated from CA. Assessment of the prognosis for a patient in this group can be made after 72 hours and a multi-modal approach to the patient is required.

Comparison of insulin responses in experiments using pooled mice islets versus islets from individual animals in the study of diabetes.

Isolated islets of Langerhans have been widely used to clarify the beta-cell function and insulin secretion in normal and diabetic states. Most of these studies have applied a pooled-islet design using isolated islets from a number of animals. However, to our knowledge, no previous studies have explored the consequences of using the pooled-islet design. From a statistical point, it may be preferable to use a design with islets from only one animal at a time under different experimental conditions and subsequently to repeat the experiments with islets from other animals. The present study compares these 2 designs in terms of their insulin response to glucose and arginine. We found higher insulin responses to glucose and arginine in pooled islets than in islets from individual animals, but differences between different stimuli were comparable between the 2 designs. However, the SEs on these differences are much smaller in the design with pooled islets than in the separate-islet design, and, consequently, corresponding P values will be much smaller. The statistical analysis of the design with islet separated per animal can explain this discrepancy because it identifies a non-ignorable random variation between animals compared with the variation within animals. In statistical terms, this implies a positive correlation between islets from the same animal. Ignoring this fact in the design with pooled islets overestimates the degrees of freedom and hence underestimates the SEs on the mean responses. This will in turn produce too small P values when using statistical tests to compare mean responses to different stimuli.

Repeated prolonged whole-body low-intensity exercise: effects on insulin sensitivity and limb muscle adaptations.

This study investigates the effect of prolonged whole-body low-intensity exercise on insulin sensitivity and the limb muscle adaptive response. Seven male subjects (weight, 90.2 +/- 3.2 kg; age, 35 +/- 3 years) completed a 32-day unsupported crossing of the Greenland icecap on cross-country skies pulling sleighs. The subjects were studied before and 3 to 4 days after the crossing of the icecap. Subjects came in overnight fasted, and an intravenous glucose tolerance test (IVGTT) was done. A biopsy was obtained from the vastus lateralis and deltoid muscle. On a separate day, a progressive test was performed to establish maximal oxygen uptake. During the crossing, subjects skied for 342 +/- 41 min/d. Peak oxygen uptake (4.6 +/- 0.2 L/min) was decreased (P < .05) by 7% after the crossing and body mass decreased (P < .05) by 7.1 +/- 0.2 kg, of which 4.4 +/- 0.5 kg was fat mass and 2.7 +/- 0.2 kg lean body mass. Glycosylated hemoglobin (5.6% +/- 0.01%) was not affected by the crossing. The IVGTT data revealed that insulin sensitivity (7.3 +/- 0.6 mU x L-1 x min-1) and glucose effectiveness (0.024 +/- 0.002 min-1) were not changed after the crossing. Similarly, the IVGTT data, when expressed per kilogram of lean body mass or body mass, were not affected by the crossing. Citrate synthase activity was higher (P < .05) in the leg (29 +/- 1 micromol x g-1 x min-1) than in the arm muscle (16 +/- 2 micromol x g-1 x min-1) and was unchanged after the crossing. Muscle GLUT4 protein concentration was higher (P < .05) in the leg (104 +/- 10 arbitrary units) than in the arm (54 +/- 9 arbitrary units) and was not changed in the leg, but was increased (P < .05) by 70% to 91 +/- 9 arbitrary units in the arm after the crossing. In conclusion, the increased glucose transporter expression in arm muscle may compensate for the loss of lean body mass and the decrease in aerobic fitness and thereby contribute to the maintenance of whole-body insulin sensitivity after prolonged low-intensity exercise training.

Stevioside does not cause increased basal insulin secretion or beta-cell desensitization as does the sulphonylurea, glibenclamide: studies in vitro.

We have shown that stevioside (SVS) enhances insulin secretion and thus may have a potential role as antihyperglycemic agent in the treatment of type 2 diabetes mellitus. However, whether SVS stimulates basal insulin secretion (BIS) and/or cause desensitization of beta cells like sulphonylureas (SU), e.g. glibenclamide (GB), is not known. To explore and compare the effects of SVS pretreatment with those of GB and glucagon-like peptide-1 (GLP-1), we exposed isolated mouse islets to low or high glucose for 1 h after short-term (2 h) or long-term (24 h) pretreatment with SVS, GB or GLP-1, respectively. BIS at 3.3 or 5.5 mM glucose were not changed after short-term pretreatment with SVS (10(-7) M), while it increased about three folds after pretreatment with GB (10(-7) M). Glucose stimulated insulin secretion (GSIS) (16.7 mM) increased dose-dependently after long-term pretreatment with SVS at concentrations from 10(-7) to 10(-5) M. Pretreatment for 24 h with GB (10(-7) M) increased the subsequent BIS (3.3 mM glucose) (p < 0.001), but decreased GSIS (16.7 mM glucose) (p < 0.001). In contrast SVS (10(-7) M) and GLP-1 (10(-7) M) did not stimulate BIS but both enhanced the subsequent GSIS (16.7 mM glucose) (p < 0.05 and p < 0.05, respectively). While SVS pretreatment increased the intracellular insulin content, GB pretreatment decreased the insulin content. Our study suggests that SVS pretreatment does not cause a stimulation of BIS and does not desensitize beta-cells, i.e. SVS seems to have advantageous characteristics to GB as a potential treatment of type 2 diabetes.