Effect of Low-Frequency Renal Nerve Stimulation on Renal Glucose Release during Normoglycemia and a Hypoglycemic Clamp in Pigs.

Previously, we demonstrated that renal denervation in pigs reduces renal glucose release during a hypoglycemic episode. In this study we set out to examine changes in side-dependent renal net glucose release (SGN) through unilateral low-frequency stimulation (LFS) of the renal plexus with a pulse generator (2-5 Hz) during normoglycemia (60 min) and insulin-induced hypoglycemia ≤3.5 mmol/L (75 min) in seven pigs. The jugular vein, carotid artery, renal artery and vein, and both ureters were catheterized for measurement purposes, blood pressure management, and drug and fluid infusions. Para-aminohippurate (PAH) and inulin infusions were used to determine side-dependent renal plasma flow (SRP) and glomerular filtration rate (GFR). In a linear mixed model, LFS caused no change in SRP but decreased sodium excretion (p < 0.0001), as well as decreasing GFR during hypoglycemia (p = 0.0176). In a linear mixed model, only hypoglycemic conditions exerted significant effects on SGN (p = 0.001), whereas LFS did not. In a Wilcoxon signed rank exact test, LFS significantly increased SGN (p = 0.03125) and decreased sodium excretion (p = 0.0017) and urinary flow rate (p = 0.0129) when only considering the first instance LFS followed a preceding period of non-stimulation during normoglycemia. To conclude, this study represents, to our knowledge, the first description of an induction of renal gluconeogenesis by LFS.

Renal Glucose Release after Unilateral Renal Denervation during a Hypoglycemic Clamp in Pigs with an Altered Hypothalamic Pituitary Adrenal Axis after Late-Gestational Dexamethasone Injection.

Previously, we demonstrated in pigs that renal denervation halves glucose release during hypoglycaemia and that a prenatal dexamethasone injection caused increased ACTH and cortisol concentrations as markers of a heightened hypothalamic pituitary adrenal axis (HPAA) during hypoglycaemia. In this study, we investigated the influence of an altered HPAA on renal glucose release during hypoglycaemia. Pigs whose mothers had received two late-gestational dexamethasone injections were subjected to a 75 min hyperinsulinaemic-hypoglycaemic clamp (<3 mmol/L) after unilateral surgical denervation. Para-aminohippurate (PAH) clearance, inulin, sodium excretion and arterio-venous blood glucose difference were measured every fifteen minutes. The statistical analysis was performed with a Wilcoxon signed-rank test. PAH, inulin, the calculated glomerular filtration rate and plasma flow did not change through renal denervation. Urinary sodium excretion increased significantly (p = 0.019). Side-dependent renal net glucose release (SGN) decreased by 25 ± 23% (p = 0.004). At 25 percent, the SGN decrease was only half of that observed in non-HPAA-altered animals in our prior investigation. The current findings may suggest that specimens with an elevated HPAA undergo long-term adaptations to maintain glucose homeostasis. Nonetheless, the decrease in SGN warrants further investigations and potentially caution in performing renal denervation in certain patient groups, such as diabetics at risk of hypoglycaemia.

No impact of weather conditions on the outcome of intensive care unit patients.

Global warming leads to increased exposure of humankind to meteorological variation, including short-term weather changes. Weather conditions involve changes in temperature, heat and cold, in air pressure and in air humidity. Every single condition influences the incidence and mortality of different diseases such as myocardial infarction and stroke. This study investigated the impact of weather conditions on short- and long-term mortality of 4321 critically ill patients (66 ± 14 years, 2638 men) admitted to an intensive care unit (ICU) over a period of 5 years. Meteorological information (air temperature, air pressure and humidity) for the same period was retrieved. The influence of absolute weather parameters, different seasons, sudden weather changes including "warm" and "cold" spells on ICU and long-term mortality was analyzed. After correction for Simplified Acute Physiology Score (SAPS-2), no impact of meteorological conditions on mortality was found. Different seasons, sudden weather changes, "warm spells" or "cold spells" did not affect the outcome of critically ill patients.

Altered Cerebral Blood Flow and Potential Neuroprotective Effect of Human Relaxin-2 (Serelaxin) During Hypoxia or Severe Hypovolemia in a Sheep Model.

Specific neuroprotective strategies to minimize cerebral damage caused by severe hypoxia or hypovolemia are lacking. Based on previous studies showing that relaxin-2/serelaxin increases cortical cerebral blood flow, we postulated that serelaxin might provide a neuroprotective effect. Therefore, we tested serelaxin in two emergency models: hypoxia was induced via inhalation of 5% oxygen and 95% nitrogen for 12 min; thereafter, the animals were reoxygenated. Hypovolemia was induced and maintained for 20 min by removal of 50% of the total blood volume; thereafter, the animals were retransfused. In each damage model, the serelaxin group received an intravenous injection of 30 µg/kg of serelaxin in saline, while control animals received saline only. Blood gases, shock index values, heart frequency, blood pressure, and renal blood flow showed almost no significant differences between control and treatment groups in both settings. However, serelaxin significantly blunted the increase of lactate during hypovolemia. Serelaxin treatment resulted in significantly elevated cortical cerebral blood flow (CBF) in both damage models, compared with the respective control groups. Measurements of the neuroproteins S100B and neuron-specific enolase in cerebrospinal fluid revealed a neuroprotective effect of serelaxin treatment in both hypoxic and hypovolemic animals, whereas in control animals, neuroproteins increased during the experiment. Western blotting showed the expression of relaxin receptors and indicated region-specific differences in relaxin receptor-mediated signaling in cortical and subcortical brain arterioles, respectively. Our findings support the hypothesis that serelaxin is a potential neuroprotectant during hypoxia and hypovolemia. Due to its preferential improvement of cortical CBF, serelaxin might reduce cognitive impairments associated with these emergencies.

Effects of iloprost on human mature osteoblasts in vitro.

BACKGROUND AND OBJECTIVES: Bone marrow oedema is a multifactorial conditioned illness. Alongside any strain relief of an affected joint, treatment with Iloprost also belongs to the choice of cures. In past studies, a modulatory effect on bone could be shown. The hypothesis of the present work is that Iloprost has a growth-stimulating effect on osteoblasts in vitro. METHODS: Human osteoblasts were isolated and cultivated. Subsequently, the cells were treated with Iloprost in bioavailable concentrations. Alterations of the cell structure were examined by means of light microscopy. A regulation of the number of vital cells was carried out by using a CASY cell counter. Possible cell impairment after Iloprost treatment was analysed by means of XTT Elisa as well as FDA and PI staining via fluorescence microscopy. RESULTS: Using light microscopy, no changes in cell structure could be observed. With the CASY cell counter, no increase in the numbers of osteoblasts appeared after Iloprost treatment. Also, XTT Elisas and fluorescence microscopy did not reveal any cell impairment due to Iloprost. CONCLUSION: Our results could not confirm a modulatory effect in mature osteoblasts. On the basis of the present work we could not verify any growth-stimulating effect by Iloprost in mature osteoblasts in vitro. Admittedly, effects had been shown previously during osteogenesis, but we do exclude an effect on mature osteoblasts which have already differentiated.

A Systematic Review of Neuroprotective Strategies in the Management of Hypoglycemia.

Severe hypogylcemia has been found to induce cerebral damage. While a number of illnesses can lead to hypoglycemic episodes, antidiabetic medications prescribed for glycemic control are a common cause. Considering the rising prevalence of diabetes mellitus in the population, we investigated neuroprotective strategies during hypoglycemia in the form of a systematic review in adherence to the PRISMA statement. A review protocol was registered in the PROSPERO database. A systematic literature search of PubMed, Web of Science, and CENTRAL was performed in September 2018. Based on a predefined inclusion protocol, results were screened and evaluated by two researchers. Both animal experiments and human studies were included, and their risk of bias was assessed with SYRCLE's and the Cochrane risk of bias tools, respectively. Of a total of 16,230 results, 145 were assessed in full-text form: 27 articles adhered to the inclusion criteria and were qualitatively analyzed. The retrieved neuroprotective strategies could be categorized into three subsets: (1) Energy substitution, (2) hypoglycemia unawareness, and (3) other neuroprotective strategies. While on a study level, the individual results appeared promising, more research is required to investigate not only specific neuroprotective strategies against hypoglycemic cerebral damage, but also its underlying pathophysiological mechanisms.

Biomimetic multilayer coatings deliver gentamicin and reduce implant-related osteomyelitis in rats.

Implant-related infections like periprosthetic joint infections (PJI) are still a challenging issue in orthopedic surgery. In this study, we present a prophylactic anti-infective approach based on a local delivery of the antibiotic gentamicin. The local delivery is achieved via a nanoscale polyelectrolyte multilayer (PEM) coating that leaves the bulk material properties of the implant unaffected while tuning the surface properties. The main components of the coating, i.e. polypeptides and sulfated glycosaminoglycans (sGAG) render this coating both biomimetic (matrix mimetic) and biodegradable. We show how adaptions in the conditions of the multilayer assembly process and the antibiotic loading process affect the amount of delivered gentamicin. The highest concentration of gentamicin could be loaded into films composed of polypeptide poly-glutamic acid when the pH of the loading solution was acidic. The concentration of gentamicin on the surface could be tailored with the number of deposited PEM layers. The resulting coatings reveal a bacteriotoxic effect on Staphylococcus cells but show no signs of cytotoxic effects on MC3T3-E1 osteoblasts. Moreover, when multilayer-coated titanium rods were implanted into contaminated medullae of rat tibiae, a reduction in the development of implant-related osteomyelitis was observed. This reduction was more pronounced for the multifunctional, matrix-mimetic heparin-based coatings that only deliver lower amounts of gentamicin.

Weather, Weather Changes and the Risk of Bell's Palsy: A Multicenter Case-Crossover Study.

BACKGROUND: To evaluate if weather or changes in weather are risk factors for Bell's palsy (BP) as exposure to draught of cold air has been popularly associated with the occurrence of BP. METHODS: Using a multicenter hospital-based case-crossover study, we analyzed the association between ambient temperature, atmospheric pressure, relative air humidity or their 24 h changes and the risk for BP in 825 patients or subgroups. RESULTS: One day following a 24 h increase in atmospheric pressure of more than 6 hPa, the risk for BP increased by 35% (OR 1.35; 95% CI 1.03-1.78) in the overall population. The risk for BP more than doubled in patients with diabetes mellitus after rapid variations in ambient temperature, independent of the direction (temperature decrease > 2.25°C; OR 2.15; 95% CI 1.08-4.25; temperature increase between 0.75 and 2.25°C; OR 2.88; 95% CI 1.63-5.10). CONCLUSIONS: Our findings support the hypothesis of an association between certain weather conditions and the risk for BP with acute changes in atmospheric pressure and ambient temperature as the main risk factors. Additionally, contrasting results for risk of BP after temperature changes in the diabetic and non-diabetic subgroups support the paradigm of a diabetic facial palsy as a distinct disease entity.

Effects of human relaxin-2 (serelaxin) on hypoxic pulmonary vasoconstriction during acute hypoxia in a sheep model.

PURPOSE: Hypoxia induces pulmonary vasoconstriction with a subsequent increase of pulmonary artery pressure (PAP), which can result in pulmonary hypertension. Serelaxin has shown an increase of pulmonary hemodynamic parameters after serelaxin injection. We therefore investigated the response of pulmonary hemodynamic parameters after serelaxin administration in a clinically relevant model. METHODS: Six controls and six sheep that received 30 µg/kg serelaxin underwent right heart catheterization during a 12-minute hypoxia period (inhalation of 5% oxygen and 95% nitrogen) and subsequent reoxygenation. Systolic, diastolic, and mean values of both PAP (respectively, PAPs, PAPd, and PAPm) and pulmonary capillary wedge pressure (respectively, PCWPs, PCWPd, and PCWPm), blood gases, heart rate (HR), and both peripheral and pulmonary arterial oxygen saturation were obtained. Cardiac output (CO), stroke volume (SV), pulmonary vascular resistance (PVR), pulmonary arterial compliance (PAcompl), and systemic vascular resistance (SVR) were calculated. RESULTS: The key findings of the current study are that serelaxin prevents the rise of PAPs (p≤0.001), PAPm, PCWPm, PCWPs (p≤0.03), and PAPd (p≤0.05) during hypoxia, while it simultaneously increases CO and SV (p≤0.001). Similar courses of decreases of PAPm, PAPd, PAPs, CO, SVR (p≤0.001), and PCWPd (p≤0.03) as compared to hypoxic values were observed during reoxygenation. In direct comparison, the experimental groups differed during hypoxia in regard to HR, PAPm, PVR, and SVR (p≤0.03), and during reoxygenation in regard to HR (p≤0.001), PAPm, PAPs, PAPd, PVR, SVR (p≤0.03), and PCWPd (p≤0.05). CONCLUSION: The findings of this study suggest that serelaxin treatment improves pulmonary hemodynamic parameters during acute hypoxia.

Underlying mechanism of subcortical brain protection during hypoxia and reoxygenation in a sheep model - Influence of α1-adrenergic signalling.

While the cerebral autoregulation sufficiently protects subcortical brain regions during hypoxia or asphyxia, the cerebral cortex is not as adequately protected, which suggests that regulation of the cerebral blood flow (CBF) is area-specific. Hypoxia was induced by inhalation of 5% oxygen, for reoxygenation 100% oxygen was used. Cortical and subcortical CBF (by laser Doppler flowmetry), blood gases, mean arterial blood pressure (MABP), heart rate and renal blood flow were constantly monitored. Low dosed urapidil was used for α1A-adrenergic receptor blockade. Western blotting was used to determine adrenergic receptor signalling mediators in brain arterioles. During hypoxia cortical CBF decreased to 72 ± 11% (mean reduction 11 ± 3%, p < 0.001) of baseline, whereas subcortical CBF increased to 168±18% (mean increase 43 ± 5%, p < 0.001). Reoxygenation led to peak CBF of 194 ± 27% in the subcortex, and restored cortical CBF. α1A-Adrenergic blockade led to minor changes in cortical CBF, but massively reduced subcortical CBF during hypoxia and reoxygenation-almost aligning CBF in both brain regions. Correlation analyses revealed that α1A-adrenergic blockade renders all CBF-responses pressure-passive during hypoxia and reoxygenation, and confirmed the necessity of α1A-adrenergic signalling for coupling of CBF-responses to oxygen saturation. Expression levels and activation state of key signalling-mediators of α1-receptors (NOSs, CREB, ERK1/2) did not differ between cortex and subcortex. The dichotomy between subcortical and cortical CBF during hypoxia and reoxygenation critically depends on α1A-adrenergic receptors, but not on differential expression of signalling-mediators: signalling through the α1A-subtype is a prerequisite for cortical/subcortical redistribution of CBF.

Pulmonary hemodynamic effects and pulmonary arterial compliance during hypovolemic shock and reinfusion with human relaxin-2 (serelaxin) treatment in a sheep model.

BACKGROUND: Previous studies on the recombinant form of human relaxin-2 (serelaxin) have shown a decrease of pulmonary hemodynamics after serelaxin injection. Currently, the effect of serelaxin treatment during hypovolemia in a large animal model remains mostly unknown. METHODS: 12 sheep were randomly assigned to a sham or serelaxin (30µg/kg serelaxin) group and underwent right heart catheterization. 50% of the estimated total blood volume were removed to induce hypovolemia, and subsequently retransfused 20 min later (reinfusion). Blood gases, heart rate, peripheral and pulmonary arterial oxygen saturation, systolic, diastolic and mean values of both pulmonary artery pressure (PAP) and pulmonary capillary wedge pressure (PCW) were measured. Cardiac output (CO), pulmonary vascular resistance (PVR), pulmonary arterial compliance (PAcompl) and systemic vascular resistance (SVR) were calculated. RESULTS: Hypovolemia and shock led to a similar decrease of PAP and PCW in both groups (p≤0.001). CO, SV and PAcompl decreased only in the control group (p≤0.05) and remained higher in the serelaxin-treated group. The results of this study suggest that serelaxin treatment did not negatively influence hemodynamic parameters during hypovolemic shock. CONCLUSION: The main conclusion of this study is that cardiopulmonary adaption mechanisms are not critically altered by serelaxin administration during severe hypovolemia and retransfusion.

The relaxin peptide family - potential future hope for neuroprotective therapy? A short review.

Since its discovery in the 1920's the relaxin peptide hormone family has not only grown in number to now seven members (relaxin-1, relaxin-2, relaxin-3, insulin-like peptide (INSL) 3, INSL4, INSL5 and INSL6), but ever more effects, suchs as vasodilatory, angiogenic, anti-apoptopic, anti-fibriotic and anti-inflammatory, have been linked to them. While relaxin-2 has mainly been investigated in the context of cardiac protection, most comprehensively in the RELAX-AHF and RELAX AHF2 studies, a small number of studies have furthermore assessed the potential neuroprotective effects of especially relaxin-2 and other members of the relaxin family. In this short review we summarise and discuss recent efforts to utilize relaxin hormones for neuroprotection and point out potential future fields of research and translational applications. While many questions still need to be answered, the promising results of the available studies definitely warrant future well-designed studies on neuroprotection by relaxin peptides.

Rapid increases in nitrogen oxides are associated with acute myocardial infarction: A case-crossover study.

Aims High concentrations of air pollutants are associated with increased risk for myocardial infarction. The European Union has defined statutory limits for air pollutants based on upper absolute concentrations. We evaluated the association between rapid changes in air pollutants and the risk of myocardial infarction independently of absolute concentrations. Methods and results Using a hospital-based case-crossover study, effects of 24h changes of nitrogen oxides (NOX/2), particulate matter (PM10), and ozone on the risk of myocardial infarction was assessed in 693 patients. In the overall population, increases of NOX of more than 20 µg/m3 within 24 h were associated with an increase in the risk of myocardial infarction by up to 121% (odds ratio (OR) 2.21, 95% confidence interval (CI) 1.19-4.08). Comparably, rapid increases of NO2 of more than 8 µg/m3 tended to increase myocardial infarction risk by 73% (OR 1.73, 95% CI 0.91-3.28) while myocardial infarction risk decreased by 60% after a decrease of NO2 concentration of more than 8 µg/m3 (OR 0.4, 95% CI 0.21-0.77), suggesting a close-to-linear association. While results for ozone concentrations were ambiguous, rapid change in PM10 was not associated with myocardial infarction risk. Conclusion Dynamics and extent of increase in nitrogen oxide concentrations may be an independent risk factor for myocardial infarction. As there are currently no European Union statutory limits reflecting this dynamic variation of air pollutants on a daily basis, the results urgently call for confirming studies in different geographical regions to verify the observations.

Impact of chronic maternal stress during early gestation on maternal-fetal stress transfer and fetal stress sensitivity in sheep.

Acute stress-induced reduction of uterine blood flow (UBF) is an indirect mechanism of maternal-fetal stress transfer during late gestation. Effects of chronic psychosocial maternal stress (CMS) during early gestation, as may be experienced by many working women, on this stress signaling mechanism are unclear. We hypothesized that CMS in sheep during early gestation augments later acute stress-induced decreases of UBF, and aggravates the fetal hormonal, cardiovascular, and metabolic stress responses during later development. Six pregnant ewes underwent repeated isolation stress (CMS) between 30 and 100 days of gestation (dGA, term: 150 dGA) and seven pregnant ewes served as controls. At 110 dGA, ewes were chronically instrumented and underwent acute isolation stress. The acute stress decreased UBF by 19% in both the CMS and control groups (p < .05), but this was prolonged in CMS versus control ewes (74 vs. 30 min, p < .05). CMS increased fetal circulating baseline and stress-induced cortisol and norepinephrine concentrations indicating a hyperactive hypothalamus-pituitary-adrenal (HPA)-axis and sympathetic-adrenal-medullary system. Increased fetal norepinephrine is endogenous as maternal catecholamines do not cross the placenta. Cortisol in the control but not in the CMS fetuses was correlated with maternal cortisol blood concentrations; these findings indicate: (1) no increased maternal-fetal cortisol transfer with CMS, (2) cortisol production in CMS fetuses when the HPA-axis is normally inactive, due to early maturation of the fetal HPA-axis. CMS fetuses were better oxygenated, without shift towards acidosis compared to the controls, potentially reflecting adaptation to repeated stress. Hence, CMS enhances maternal-fetal stress transfer by prolonged reduction in UBF and increased fetal HPA responsiveness.

Effects of Late Gestational Fetal Exposure to Dexamethasone Administration on the Postnatal Hypothalamus-Pituitary-Adrenal Axis Response to Hypoglycemia in Pigs.

BACKGROUND: Prenatal glucocorticoid administration alters the activity of the fetal hypothalamic-pituitary-adrenocortical axis (HPAA), and correspondingly the adenocorticotropic hormone (ACTH) and cortisol levels after birth. The dosages required for these effects are critically discussed. Activation of the HPAA is related to metabolic syndrome and diabetes mellitus. Hypoglycemia is the classic side effect of antidiabetic treatment. We hypothesized that a low dosage of dexamethasone in late pregnancy alters the HPAA response to hypoglycemia in pigs. METHODS: 12 pregnant sows were randomly assigned to two groups which received either a low-dose intramuscular injection (99th and 100th day of gestation) of dexamethasone (0.06 µg/kg body weight) or vehicle. Three months after birth, 18 dexamethasone-treated anaesthetized offspring and 12 control offspring underwent a 75 min hypoglycemic clamp (blood glucose below 4 mmol/L) procedure. Heart rate (HR), blood pressure, ACTH and cortisol levels and body weight (at birth and after three months) were recorded. RESULTS: Dexamethasone-treated animals exhibited significantly elevated ACTH (139.9 ± 12.7 pg/mL) and cortisol (483.1 ± 30.3 nmol/L) levels during hypoglycemia as compared to the control group (41.7 ± 6.5 pg/mL and 257.9 ± 26.7 nmol/L, respectively), as well as an elevated HR (205.5 ± 5.7 bpm) and blood pressure (systolic: 128.6 ± 1.5, diastolic: 85.7 ± 0.7 mmHg) response as compared to the control group (153.2 ± 4.5 bpm; systolic: 118.6 ± 1.6, diastolic: 79.5 ± 1.4 mmHg, respectively; p < 0.001). CONCLUSIONS: Low-dose prenatal administration of dexamethasone not only exerts effects on the HPAA (ACTH and cortisol concentration) and vital parameters (HR and diastolic blood pressure) under baseline conditions, but also on ACTH, HR and systolic blood pressure during hypoglycemia.

A Systematic Review of Neuroprotective Strategies during Hypovolemia and Hemorrhagic Shock.

Severe trauma constitutes a major cause of death and disability, especially in younger patients. The cerebral autoregulatory capacity only protects the brain to a certain extent in states of hypovolemia; thereafter, neurological deficits and apoptosis occurs. We therefore set out to investigate neuroprotective strategies during haemorrhagic shock. This review was performed in accordance to the PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-Analyses) guidelines. Before the start of the search, a review protocol was entered into the PROSPERO database. A systematic literature search of Pubmed, Web of Science and CENTRAL was performed in August 2017. Results were screened and evaluated by two researchers based on a previously prepared inclusion protocol. Risk of bias was determined by use of SYRCLE's risk of bias tool. The retrieved results were qualitatively analysed. Of 9093 results, 119 were assessed in full-text form, 16 of them ultimately adhered to the inclusion criteria and were qualitatively analyzed. We identified three subsets of results: (1) hypothermia; (2) fluid therapy and/or vasopressors; and (3) other neuroprotective strategies (piracetam, NHE1-inhibition, aprotinin, human mesenchymal stem cells, remote ischemic preconditioning and sevoflurane). Overall, risk of bias according to SYRCLE's tool was medium; generally, animal experimental models require more rigorous adherence to the reporting of bias-free study design (randomization, etc.). While the individual study results are promising, the retrieved neuroprotective strategies have to be evaluated within the current scientific context-by doing so, it becomes clear that specific promising neuroprotective strategies during states of haemorrhagic shock remain sparse. This important topic therefore requires more in-depth research.

A Simple Procedure for the Evaluation of Bone Vitality by Staining with a Tetrazolium Salt.

Presently, no intra-operative method for a direct assessment of bone vitality exists. Therefore, we set out to test the applicability of tetrazolium-based staining on bone samples. The explanted femoral heads of 37 patients were used to obtain either cancellous bone fragments or bone slices. Samples were stained with 2,3,5-triphenyl-2H-tetrazolium chloride (TTC) or 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (thiazolyl blue, MTT) at different times (one to twelve hours) after explantation. Staining was quantified either spectrophotometrically after extraction of the dyes or by densitometric image analysis. TTC-staining of cancellous bone fragments and bone slices, respectively, indicated the detectability of vital cells in both types of samples in a window of up to six hours after explantation. Staining intensity at later time-points was indistinguishable from the staining of untreated samples or sodium azide treated samples, which represent dead cells. In contrast, MTT-staining of bone slices revealed intense unspecific staining, which obscured the evaluation of the vitality of the samples. The lack of a detectable increase of colour intensity in TTC-stained bone samples, which were treated more than six hours after explantation, corresponds to reduced fracture healing. The described simple procedure could provide a basis for an intraoperative decision by the orthopaedic surgeon.

Redistribution of Cerebral Blood Flow during Severe Hypovolemia and Reperfusion in a Sheep Model: Critical Role of α1-Adrenergic Signaling.

BACKGROUND: Maintenance of brain circulation during shock is sufficient to prevent subcortical injury but the cerebral cortex is not spared. This suggests area-specific regulation of cerebral blood flow (CBF) during hemorrhage. METHODS: Cortical and subcortical CBF were continuously measured during blood loss (≤50%) and subsequent reperfusion using laser Doppler flowmetry. Blood gases, mean arterial blood pressure (MABP), heart rate and renal blood flow were also monitored. Urapidil was used for α1A-adrenergic receptor blockade in dosages, which did not modify the MABP-response to blood loss. Western blot and quantitative reverse transcription polymerase chain reactions were used to determine adrenergic receptor expression in brain arterioles. RESULTS: During hypovolemia subcortical CBF was maintained at 81 ± 6% of baseline, whereas cortical CBF decreased to 40 ± 4% (p < 0.001). Reperfusion led to peak CBFs of about 70% above baseline in both brain regions. α1A-Adrenergic blockade massively reduced subcortical CBF during hemorrhage and reperfusion, and prevented hyperperfusion during reperfusion in the cortex. α1A-mRNA expression was significantly higher in the cortex, whereas α1D-mRNA expression was higher in the subcortex (p < 0.001). CONCLUSIONS: α1-Adrenergic receptors are critical for perfusion redistribution: activity of the α1A-receptor subtype is a prerequisite for redistribution of CBF, whereas the α1D-receptor subtype may determine the magnitude of redistribution responses.

Pulmonary arterial compliance and pulmonary hemodynamic effects of Serelaxin in a sheep model.

BACKGROUND: The influence of the recombinant form of human relaxin-2 (serelaxin) on pulmonary hemodynamics under physiologic conditions have not been the subject of studies in an animal model up until now. METHODS: We therefore utilised the large animal model sheep, convenient in its similar cardiovascular physiology, to investigate said influence. All animals underwent right heart catheterization, a safe and reliable invasive procedure for the assessment of pulmonary hemodynamics, and then received either 30µg/kg serelaxin (n = 11) or saline (n = 13). Systolic, diastolic and mean values of both pulmonary artery pressure (respectively, PAPs, PAPd, PAPm) and pulmonary capillary wedge pressure (respectively, PCWs, PCWd, PCWm) blood gases, heart rate (HR) and both peripheral and pulmonary arterial oxygen saturation were obtained. Cardiac output (CO), pulmonary vascular resistance (PVR), pulmonary arterial compliance (PAcompl) and systemic vascular resistance (SVR) were calculated. RESULTS: The key findings of the current study are that 20 min after serelaxin injection a rapid decrease of the PAPm, PCWPm, SVR and an decrease of the PAcompl was observed (P < 0.01). CONCLUSION: These findings suggest that serelaxin might be suitable to improve pulmonary hemodynamics in clinically relevant scenarios, like acute heart failure or pulmonary hypertension.

Weather as a risk factor for epileptic seizures: A case-crossover study.

OBJECTIVE: Most epileptic seizures occur unexpectedly and independently of known risk factors. We aimed to evaluate the clinical significance of patients' perception that weather is a risk factor for epileptic seizures. METHODS: Using a hospital-based, bidirectional case-crossover study, 604 adult patients admitted to a large university hospital in Central Germany for an unprovoked epileptic seizure between 2003 and 2010 were recruited. The effect of atmospheric pressure, relative air humidity, and ambient temperature on the onset of epileptic seizures under temperate climate conditions was estimated. RESULTS: We found a close-to-linear negative correlation between atmospheric pressure and seizure risk. For every 10.7 hPa lower atmospheric pressure, seizure risk increased in the entire study population by 14% (odds ratio [OR] 1.14, 95% confidence interval [CI] 1.01-1.28). In patients with less severe epilepsy treated with one antiepileptic medication, seizure risk increased by 36% (1.36, 1.09-1.67). A high relative air humidity of >80% increased seizure risk in the entire study population by up to 48% (OR 1.48, 95% CI 1.11-1.96) 3 days after exposure in a J-shaped association. High ambient temperatures of >20°C decreased seizure risk by 46% in the overall study population (OR 0.54, 95% CI 0.32-0.90) and in subgroups, with the greatest effects observed in male patients (OR 0.33, 95% CI 0.14-0.74). SIGNIFICANCE: Low atmospheric pressure and high relative air humidity are associated with an increased risk for epileptic seizures, whereas high ambient temperatures seem to decrease seizure risk. Weather-dependent seizure risk may be accentuated in patients with less severe epilepsy. Our results require further replication across different climate regions and cohorts before reliable clinical recommendations can be made.