Papers by Michael Kristensen
Culicoides vectors are critical to the survival and transmission of bluetongue virus as infection... more Culicoides vectors are critical to the survival and transmission of bluetongue virus as infection only occurs in areas or regions where competent vectors are present. The success of Culicoides biting midges as vectors is mainly related to their vast population sizes and to their means of dispersal. Their choice of host for blood feeding is sparsely described. The aim of the present study was to establish methods for the identification of bloodmeal hosts and determine the identity and diversity of bloodmeals of vertebrate hosts from wild-caught biting midges near livestock farms. The study includes some of the most common and abundant species of biting midges in Denmark: Culicoides obsoletus, Culicoides scoticus, Culicoides pulicaris and Culicoides punctatus. We collected 8,378 biting midges including nine species of Culicoides of which blood-fed specimens were found from six species. We identified 251 blood engorged biting midges, and hosts were identified in 115 of 125 analysed spe...
Posterino, Giuseppe S., and Martin W. Fryer. Effects of high myoplasmic L-lactate concentration o... more Posterino, Giuseppe S., and Martin W. Fryer. Effects of high myoplasmic L-lactate concentration on E-C coupling in mammalian skeletal muscle. J Appl Physiol 89: 517-528, 2000.-The effects of high myoplasmic L-lactate concentrations (20-40 mM) at constant pH (7.1) were investigated on contractile protein function, voltage-dependent Ca 2ϩ release, and passive Ca 2ϩ leak from the sarcoplasmic reticulum (SR) in mechanically skinned fast-twitch (extensor digitorum longus; EDL) and slow-twitch (soleus) fibers of the rat. L-Lactate (20 mM) significantly reduced maximum Ca 2ϩ -activated force by 4 Ϯ 0.5% (n ϭ 5, P Ͻ 0.05) and 5 Ϯ 0.4% (n ϭ 6, P Ͻ 0.05) for EDL and soleus, respectively. The Ca 2ϩ sensitivity was also significantly decreased by 0.06 Ϯ 0.002 (n ϭ 5, P Ͻ 0.05) and 0.13 Ϯ 0.01 (n ϭ 6, P Ͻ 0.001) pCa units, respectively. Exposure to L-lactate (20 mM) for 30 s reduced depolarization-induced force responses by ChCl substitution by 7 Ϯ 3% (n ϭ 17, P Ͻ 0.05). This inhibition was not obviously affected by the presence of the lactate transport blocker quercetin (10 M), or the chloride channel blocker anthracene-9-carboxylic acid (100 M). L-Lactate (20 mM) increased passive Ca 2ϩ leak from the SR in EDL fibers (the integral of the response to caffeine was reduced by 16 Ϯ 5%, n ϭ 9, P Ͻ 0.05) with no apparent effect in soleus fibers (100 Ϯ 2%, n ϭ 3). These results indicate that the L-lactate ion per se has negligible effects on either voltage-dependent Ca 2ϩ release or SR Ca 2ϩ handling and exerts only a modest inhibitory effect on muscle contractility at the level of the contractile proteins. muscle fatigue; excitation-contraction coupling; contractile apparatus; calcium release IN MOST INSTANCES, MUSCLE FATIGUE is associated with prolonged periods of intermittent contractions that typically give rise to alterations in the level of myoplasmic metabolites [see review by Fitts and Allen et al. ]. Lactic acidosis is thought to be a major factor in such metabolic fatigue. Acidosis of the myoplasm per se has been shown to affect such parameters as maximum Ca 2ϩ -activated force, Ca 2ϩ sensitivity of the myofilaments, and Ca 2ϩ release from ryanodine receptors [see review by Allen et al. (1)]. However, in mammalian muscle, the effects of acidosis on these parameters are small , indicating that other metabolic changes are largely responsible for the decline in force in mammalian muscle.
British Journal of Anaesthesia, 2015
Editor-Correct identification of the cricothyroid membrane is crucial in preparation for emergenc... more Editor-Correct identification of the cricothyroid membrane is crucial in preparation for emergency airway management. However, the conventional method, inspection and palpation, has a low success rate, 1 especially in women (24-35%). We have previously described a structured stepwise method for ultrasonographic identification of the cricothyroid membrane, 3 4 in which it is not necessary to see or palpate any landmarks on the neck for successful identification. The method involves ultrasonographic identification of the trachea in the transverse plane, rotating the transducer to the longitudinal plane, and identifying the image of the anterior parts of the tracheal rings and the cricothyroid cartilage. Using its ability to cast a shadow on the ultrasound image, an i.v. needle is slid between the transducer and the skin, without penetrating the skin, until it is immediately cranial to the cricoid cartilage, thus indicating the cricothyroid membrane ( ).
Acta Anaesthesiologica Scandinavica, Oct 1, 2001
Background: Problems with managing the airways in relation to anaesthesia causes severe morbidity... more Background: Problems with managing the airways in relation to anaesthesia causes severe morbidity and mortality. A large proportion of these adverse respiratory events is preventable. Still patients continue to die from airway disasters related to anaesthesia, also in Scandinavia. The goal of this study is to identify which efforts are likely to improve this situation.
Intens Care Med, 1991
We prospectively recorded the frequency with which ICU personnel came in contact with body fluids... more We prospectively recorded the frequency with which ICU personnel came in contact with body fluids in order to provide an empirical basis for the recommendation of relevant protective precautions. ICU personnel completed a questionnaire when performing a range of 29 standardized procedures. The rate of contact with body fluid was: manual ventilation (5507o); catheterization of peripheral vein (3607o); insertion of central venous catheter (6907o); arterial puncture (1807o); tracheal intubation (7607o); tracheal extubation (8707o); suction from mouth, pharynx or trachea (8207o); drawing of blood sample (5207o); establishing or discontinuing blood transfusion (5007o); establishing or discontinuing infusion (2007o); changing of wound dressing (5207o). We suggest that the contact rates observed should be used in combination with a universal precautions policy, in order to identify procedures that are likely to involve contact with body fluid. By using gloves 9507o of contacts to body fluid would have been prevented.
Undulant Fever in Denmark
Seuchenbekampfung, 1930
Positron emission tomography/computed tomography for optimized colon cancer staging and follow up
Scandinavian Journal of Gastroenterology, Nov 29, 2013
Exercise increases the concentration of phospholemman (FXYD1) in sarcolemma membrane from rat skeletal muscle
The Faseb Journal, Mar 1, 2006
Tracheal intubation in patients with anticipated difficult airway using Boedeker intubation forceps and McGrath videolaryngoscope
Acta Anaesthesiologica Scandinavica, 2015
ABSTRACT Background Videolaryngoscopes with sharp angulated blades improve the view of the vocal ... more ABSTRACT Background Videolaryngoscopes with sharp angulated blades improve the view of the vocal cords but this does not necessarily result in higher success rates of intubation The aim of this study was to evaluate the efficacy of using Boedeker intubation forceps in conjunction with McGrath Series 5 Videolaryngoscope (MVL) in patients with predictors for difficult intubation.Methods The study was conducted at the Department of Anaesthesia, Copenhagen University Hospital from September to December 2013. Patients with one or more predictors of difficult intubation scheduled for general anaesthesia were assessed for eligibility. Patients were intubated using Boedeker intubation forceps and MVL. The primary endpoint was time to intubation. The secondary endpoints were intubation success rate, number of intubation attempts, intubation conditions and post-operative hoarseness.ResultsThirty-three patients were assessed for eligibility, and 25 patients were included in the study with a median SARI score of 3 (IQR 3–4). Twenty-two (88%, 95% confidence interval [74–100%]) of the patients were successfully intubated by the method with a median time to intubation of 115 s (IQR 78–247). Steering and advancement of the tube were reported as acceptable in 21 (84%) and 22 cases (88%), respectively, and excellent in 10 cases (45%) for both measures. Ten cases (40%) were intubated on the first attempt. There were three cases (12%) of failed intubation; in these cases, successful intubation was obtained by using a styletted tube.Conclusion(s)Most patients with anticipated difficult intubation can be successfully intubated with Boedeker intubation forceps and MVL. However, endotracheal tube placement failed in 3/25 patients despite a good laryngeal view.
Plasma volume, fluid shifts, and renal responses in humans during 12 h head-out water immersion
Journal of Applied Physiology
Changes in plasma volume (PV) throughout 12 h of thermoneutral (34.5 degrees C) water immersion (... more Changes in plasma volume (PV) throughout 12 h of thermoneutral (34.5 degrees C) water immersion (WI) were evaluated in eight subjects by an improved Evans blue (EB) technique and by measurements of hematocrit (Hct), hemoglobin (Hb), and plasma protein concentrations (Pprot). Appropriate time control studies (n = 6) showed no measurable change in PV. At 30 min of immersion, EB measurements demonstrated an increase in PV of 16 +/- 2% (457 +/- 70 ml). Calculations, however, based on concomitant changes in Hct, Hb, and Pprot showed an increase in PV of only 6.9 +/- 0.9 to 10.0 +/- 0.8% at 30 min of WI. PV values based on EB measurements subsequently declined throughout WI to (but not below) the preimmersion level. Concomitantly, changes in PV calculated from Pprot values remained increased, whereas estimations of changes in PV based on Hct and Hb values returned to prestudy levels after 4 h of immersion. It is concluded that PV initially increases by 16 +/- 2% during WI and does not decline below preimmersion and control levels during 12 h of immersion despite a loss of 0.9 +/- 0.2 liter of body fluid. Furthermore, changes in Hct, Hb, and Pprot do not provide accurate measures of the changes in PV during WI in humans.
Overview: House flies are carriers of dozens of devastating diseases that have severe consequence... more Overview: House flies are carriers of dozens of devastating diseases that have severe consequences for human and animal health. Despite the fact that it is a passive vector, a key bottleneck to progress in controlling the devastating human diseases transmitted by house flies is lack of knowledge of the basic molecular biology of this species. Sequencing of the house fly genome will provide important inroads to the discovery of novel target sites for house fly control, understanding of the immune response in this dung-living fly, rapid elucidation of insecticide resistance genes and understanding of numerous aspects of the basic biology of this insect pest. The ability of the house fly to prosper in a remarkably septic environment motivates analysis of its innate immune system. Its polymorphic sex determination system, with male- determining factors on either the autosomes or the Y chromosome, is ripe for a genomic analysis. In addition, the house fly is well placed phylogenetically ...
Based on historical data on the number of inquiries to the advisory service at the Danish Pest In... more Based on historical data on the number of inquiries to the advisory service at the Danish Pest Infestation Laboratory we have tried to analyse the variation in bed bug infestations in Denmark since the 1950s. The bed bug problems in Denmark have gone from low levels in the 1950s, gradually increasing to a peak in the mid-1980s. From there on the problems diminished, but were still present. In the last 10 years the problems are increasing again. The available information from other European countries seems to indicate that this is the same situation in many countries. One possible reason for the recent increase in the bed bug problems is resistance against the available insecticides. To investigate this possibility we collected bed bugs from 20 different locations in Denmark and tested their sensitivity against chlorpyrifos, permethrin and deltamethrin; the most important insecticides registered in Denmark for bed bug control. Compared with a sensitive US strain there was widespread ...
Sequencing of the house fly (Musca domestica) genome and transcriptome
Abstract Based on historical data on the number of inquiries to the advisory service at the Danis... more Abstract Based on historical data on the number of inquiries to the advisory service at the Danish Pest Infestation Laboratory we have tried to analyse the variation in bed bug infestations in Denmark since the 1950s. The bed bug problems in Denmark have gone from low levels in the 1950s, gradually increasing to a peak in the mid-1980s. From there on the problems diminished, but were still present. In the last 10 years the problems are increasing again. The available information from other European countries seems to indicate that this ...
Morphological and molecular identification of species of the Obsoletus group (Diptera: Ceratopogonidae) in Scandinavia
Parasitology Research
After the introduction of bluetongue in northern Europe in 2006, populations of Culicoides have b... more After the introduction of bluetongue in northern Europe in 2006, populations of Culicoides have been monitored in many European countries. Large quantities of Culicoides specimens shall be determined to species, and it is thus important to find reliable morphological characters that are visualized in a stereomicroscope. Culicoides obsoletus, Culicoides scoticus, Culicoides chiopterus, and Culicoides dewulfi all belonging to subgenus Avaritia are common in collections in northern Europe. C. obsoletus and C. scoticus often make up more than 50% of the total catch of biting midges. Separation of the females of the four species by morphological characters has frequently been questioned, and in many cases, female specimens are grouped as an entity in veterinary and ecological studies. We show how it is possible using a stereomicroscope to separate the females of the four species by combining the shape of the third segment of the maxillary palp and the number and location of hairs on the ...
Klinisk ultralydskanning ved luftvejshåndtering
To create a state-of-the-art overview of the new and expanding role of ultrasonography in clinica... more To create a state-of-the-art overview of the new and expanding role of ultrasonography in clinical decision-making, intervention and management of the upper and lower airways, that is clinically relevant, up-to-date and practically useful for clinicians. This is a narrative review combined with a structured Medline literature search. Ultrasonography can be utilised to predict airway difficulty during induction of anaesthesia, evaluate if the stomach is empty or possesses gastric content that poses an aspiration risk, localise the essential cricothyroid membrane prior to difficult airway management, perform nerve blocks for awake intubation, confirm tracheal or oesophageal intubation and facilitate localisation of tracheal rings for tracheostomy. Ultrasonography is an excellent diagnostic tool in intraoperative and emergency diagnosis of pneumothorax. It also enables diagnosis and treatment of interstitial syndrome, lung consolidation, atelectasis, pleural effusion and differentiates...
Importance of pH regulation and lactate/H+ transport capacity for work production during supramaximal exercise in humans
Journal of Applied Physiology
We examine the influence of the cytosolic and membrane-bound contents of carbonic anhydrase (CA; ... more We examine the influence of the cytosolic and membrane-bound contents of carbonic anhydrase (CA; CAII, CAIII, CAIV, and CAXIV) and the muscle content of proteins involved in lactate and proton transport [monocarboxylate transporter (MCT) 1, MCT4, and Na(+)/H(+) exchanger 1 (NHE1)] on work capacity during supramaximal exercise. Eight healthy, sedentary subjects performed exercises at 120% of the work rate corresponding to maximal oxygen uptake (W(max)) until exhaustion in placebo (Con) and metabolic alkalosis (Alk) conditions. The total (W(tot)) and supramaximal work performed (W(sup)) was measured. Muscle biopsies were obtained before and immediately after standardized exercises (se) at 120% W(max) in both conditions to determine the content of the targeted proteins, the decrease in muscle pH (DeltapH(m)), and the muscle lactate accumulation ([Lac](m)) per joule of W(sup) (DeltapH(m)/W(sup-se) and Delta[Lac](m)/W(sup-se), respectively) and the dynamic buffer capacity. In Con, W(sup)...
Journal of Membrane Biology
Na,K-ATPase activity, which is crucial for skeletal muscle function, undergoes acute and long-ter... more Na,K-ATPase activity, which is crucial for skeletal muscle function, undergoes acute and long-term regulation in response to muscle activity. The aim of the present study was to test the hypothesis that AMP kinase (AMPK) and the transcriptional coactivator PGC-1α are underlying factors in long-term regulation of Na,K-ATPase isoform (α,β and PLM) abundance and Na(+) affinity. Repeated treatment of mice with the AMPK activator AICAR decreased total PLM protein content but increased PLM phosphorylation, whereas the number of α- and β-subunits remained unchanged. The K(m) for Na(+) stimulation of Na,K-ATPase was reduced (higher affinity) after AICAR treatment. PLM abundance was increased in AMPK kinase-dead mice compared with control mice, but PLM phosphorylation and Na,K-ATPase Na(+) affinity remained unchanged. Na,K-ATPase activity and subunit distribution were also measured in mice with different degrees of PGC-1α expression. Protein abundances of α1 and α2 were reduced in PGC-1α +/-...
AJP Advances in Physiology Education
Experimental designs involving repeated measurements on experimental units are widely used in phy... more Experimental designs involving repeated measurements on experimental units are widely used in physiological research. Often, relatively many consecutive observations on each experimental unit are involved and the data may be quite nonlinear. Yet evidently, one of the most commonly used statistical methods for dealing with such data sets in physiological research is the repeated-measurements ANOVA model. The problem herewith is that it is not well suited for data sets with many consecutive measurements; it does not deal with nonlinear features of the data, and the interpretability of the model may be low. The use of inappropriate statistical models increases the likelihood of drawing wrong conclusions. The aim of this article is to illustrate, for a reasonably typical repeated-measurements data set, how fundamental assumptions of the repeated-measurements ANOVA model are inappropriate and how researchers may benefit from adopting different modeling approaches using a variety of diffe...
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Papers by Michael Kristensen