Dirofilaria-repens-Befall in einem Schlittenhunde-Rudel im Land Brandenburg

Gegenstand und Ziel: In den letzten Jahren hat Dirofilaria (D.) repens erheblich an Bedeutung gewonnen. Infolge der globalen Erwärmung und des zunehmenden internationalen Haustierverkehrs ist eine weitere Ausbreitung des vektorgebundenen Parasiten aus seinen angestammten Habitaten Richtung Nordeuropa denkbar. Bei einem Tier aus einem Rudel von 29 Schlittenhunden wurden bei einer Routineuntersuchung Mikrofilarien im Blut festgestellt. Dies gab Anlass zur Untersuchung des ganzen Rudels. Ziele waren Art-diagnose der Filarien, Darstellung des Vorkommens der Filariose im Rudel und Prüfung einer neuen filariziden Behandlungsstrategie. Material und Methoden: Neben der Untersuchung auf Filarien erfolgte eine hämatologische Untersuchung. Zur Detektion der Mikrofilarien diente der Knott-Test. Aus den Proben der positiven Tiere wurde eine PCR zur Artdiagnose durchgeführt. Die für Mikrofilarien positiven Hunde wurden mit Doxycyclin und Ivermectin behandelt. Ergebnisse: Fünf von 29 Tieren waren mit D. repens infiziert. Ein Patient zeigte Hautveränderungen, die anderen Hunde präsentierten sich klinisch unauffällig. Bei den hämatologischen Parametern wiesen sie jedoch signifikante Abweichungen auf. Vier und 19 Wochen nach Abschluss der 6-wöchigen Behandlung waren mittels Knott-Test keine Mikrofilarien mehr nachweisbar. Schlussfolgerung und klinische Relevanz: Die kanine kutane Dirofilariose (D. repens) ist in Deutschland nicht mehr als ausschließlich importierte Krankheit anzusehen. Für die Wahl einer adäquaten Therapie hat eine Artdiagnose entscheidende Bedeutung. Die PCR stellt hierfür eine sichere Methode dar. Durch die Kombinationstherapie mit Ivermectin und Doxycyclin kann eine Amikrofilarämie erreicht werden. Da sich ein Befall der Endwirte nur selten klinisch äußert, sind prophylaktische Maßnahmen zur Limitierung einer Ausbreitung des Parasiten in potenziellen Risikogebieten zu diskutieren. Bei Hunden mit pruriginösen, nodulären Dermatitiden sollte D. repens differenzialdiagnostisch in Erwägung gezogen werden.

Co-infection of Trypanosoma pestanai and Anaplasma phagocytophilum in a dog from Germany

Infections with arthropod-borne pathogens are an increasing threat world-wide that requires heightened vigilance from veterinary and medical practitioners, especially when they involve new or unusual organisms. A dog was presented to a local veterinary clinic in Germany with malaise, pale mucous membranes and stiff joints. Clinical assessment revealed pyrexia, leukopenia and thrombocytopenia. On suspicion of a tick-borne infection, blood samples were examined for clinical and biochemical parameters and subjected to a Anaplasma phagocytophilum-, Borrelia spp.- and Ehrlichia canis-specific real-time PCR. Additionally, a sample of the pre-therapeutic buffy coat was co-cultured with the Ixodes scapularis cell-line ISE6 for 20days. Only the PCR specific for A. phagocytophilum DNA yielded a positive result, and furthermore, Anaplasma morulae were visible in granulocytes and tick cells. After co-culturing, extracellular trypomastigote and epimastigote stages of Trypanosoma sp. with an average length of 29.7μm were observed, featuring a pointed posterior end. Sequence analysis of a 2080bp fragment of the 18S rRNA gene showed 99% identity to the 18S rRNA gene of Trypanosoma pestanai, previously described from a European badger (Meles meles) in France. The dog's condition improved rapidly in response to doxycycline treatment for three weeks. The clinical status normalized and clinical blood parameters were found to be within the reference ranges. To our knowledge this is the first description of T. pestanai infection in a dog, the first detection of T. pestanai in Germany and the first documented co-infection with these two pathogens. Co-infections with unusual opportunistic vector-borne pathogens should be considered, if acute canine granulocytic anaplasmosis is evident.

[Dirofilaria repens-infection in a dog in central Germany without any history of travel]

A mixed breed dog was presented with dyspnoea and fever. In the purulent thorax aspirate, a nematode larva was found during the cytological examination. Subsequent diagnostic tests revealed an infection with Dirofilaria repens, which was probably acquired autochthonously in central Germany. Moxidectin was administered every 4 weeks for 6 months and shown to be effective as indicated by subsequent blood examinations. This case report shows that infection with Dirofilaria repens is possible in Germany and can be treated successfully.

Effects of curcumin on Cryptosporidium parvum in vitro

Cryptosporidium parvum is a zoonotic protozoan parasite having peculiarities among the apicomplexa that could be responsible for its resistance to some drugs and disinfectants against coccidia. The awareness of Cryptosporidium as a health problem in man and animal is increasing and potent drugs are urgently needed. Curcumin, a natural polyphenolic compound, has been found to be active against a variety of diseases including anticarcinogenic, antimicrobial, and antiprotozoal effects. We investigated the effects of curcumin on infectivity and development of C. parvum in a recently established in vitro system combining infection of human ileocecal adenocarcinoma cell cultures with quantification of intracellular parasites by quantitative polymerase chain reaction. Curcumin was found to be effective (>95% inhibition of parasite growth) at 50 microM for 24 h when infected cultures were exposed for more than 12 h. Withdrawal of curcumin after 24 h of exposure did not result in a significant resumption of C. parvum growth. The invasion of host cells by sporozoites (infectivity) was found to be inhibited at least 65% in the presence of 200 microM curcumin. No significant reduction of viability of C. parvum oocysts after incubation with curcumin was recorded. Altogether, curcumin showed promising anticryptosporidial effects under in vitro conditions and deserves further exploration.

Mechanical deformation of ventricular myocytes modulates both TRPC6 and Kir2.3 channels

Cardiomyocytes respond to mechanical stretch with an increase [Ca2+]i. Here, we analyzed which ion channels could mediate this effect. Murine ventricular myocytes were attached to a glass coverslip and a cell-attached glass stylus sheared the upper cell part versus the attached cell bottom. At negative clamp potentials, stretch induced inward currents that increased with the extent of stretch and reversed within 2 min after relaxation from stretch. Stretch activated a nearly voltage-independent GsMTx-4-sensitive non-selective cation conductance Gns, antibodies against TRPC6 prevented Gns activation. In addition, stretch deactivated a Cs+-sensitive inwardly rectifying potassium conductance GK1, antibodies against Kir2.3 inhibited this effect. Immunolabeling localized TRPC6 and Kir2.3 in T-tubular membranes, and stretch-induced changes in membrane currents were absent in cells whose T-tubules had been removed. In absence of stretch, we could activate Gns and deactivate GK1 by 1-oleoyl-2-acetyl-sn-glycerol (OAG) and other amphipaths. We interpret that the function of TRPC6 and Kir2.3 channels is controlled by both tension and curvature of the surrounding lipid bilayer that are changed by incorporation of amphipaths. Stretch-activation of TRPC6 channels may increase Ca2+ influx directly and indirectly, by membrane depolarization (activation of voltage-gated Ca2+ channels) and by elevated [Na+]i (augmented Na+,Ca2+-exchange).

Bending of z-lines by mechanical stimuli: an input signal for integrin dependent modulation of ion channels?

We studied which components of mechanical cell deformation are involved in "stretch modulated ion currents" (SMIC). Murine ventricular myocytes were attached to glass coverslips and deformed in x, y and z with a 16 microm thin glass stylus (S) of calibrated stiffness. Three-dimensional confocal microscopy characterized cell deformation (T-tubular membranes, mitochondria) and bending of S (indicative of the applied force). Axial (x-) displacement of S sheared the upper cell part versus the attached bottom, close to S, it changed sarcomere length and bent z-lines ("z-line displacement"). Vertical (z-press) or transversal (y-shear) displacement of S bulged cytoplasm and mitochondria transversally without detectable z-line displacement. Axial stiffness increased with the extent of stress ("stress stiffening"). Depolymerization of F-actin or block of integrin receptors reduced stiffness. SMIC served as a proxy readout of deformation-induced signaling. Axial deformation activated a non-selective cation conductance (Gns) and deactivated an inwardly rectifying K+ conductance (GK1), z-press or y-shear did not induce SMIC. Depolymerization of F-actin or block of integrin receptors reduced SMIC. SMIC did not depend on changes in sarcomere length but correlated with the extent of z-line bending. We discuss that both shear stress at the attached cell bottom and z-line bending could activate mechanosensors. Since SMIC was absent during deformations without z-line bending we postulate that z-line bending is a necessary component for SMIC signaling.

Aging aggravates heterogeneities in cell-size and stress-intolerance of cardiac ventricular myocytes

RATIONALE

Heterogeneity of ventricular myocytes from old murine hearts was tested in regard to cell volume and tolerance to stress induced by ROS generated by photoactivation of tetramethylrhodamine methylester.

RESULTS

During repetitive linescans, ROS generated 'scars' of depolarized mitochondria. All young and 60% of old myocytes had type1 scars that were small and remained stable with time. Forty percent cells from old hearts responded with type2 scars that were wide and expanded with time. Depolarization of individual mitochondria was characterized by its half decay time. HDT was 6.9s in young mice (type1 mitochondria). HDT was 5.6s in old mice due to a 30% population of mitochondria with reduced ROS-tolerance (type2, HDT=3.0 s). Type1 and type2 mitochondria did not coexist in the same cell, however, in the same old heart (different myocytes). In a different set of myocytes the volumes were measured to be larger (83+/-29 pl) and more heterogeneous than in young myocytes (49+/-13 pl).

CONCLUSION

Hearts of old mice contain a subpopulation of myocytes with reduced mitochondrial stress-tolerance that is attributed to an age-dependent reduction of cellular ROS defence capacity. We discuss how heterogeneities in stress-tolerance and cell volume could be causally linked.