Light-Controlled Supramolecular Helicity of a Liquid Crystalline Phase Using a Helical Polymer Functionalized with a Single Chiroptical Molecular Switch

Control over the preferred helical sense of a poly(n-hexyl isocyanate) (PHIC) by using a single light-driven molecular motor, covalently attached at the polymer’s terminus, has been accomplished in solution via a combination of photochemical and thermal isomerizations. Here, we report that after redesigning the photochromic unit to a chiroptical molecular switch, of which the two states are thermally stable but photochemically bistable, the chiral induction to the polymer’s backbone is significantly improved and the handedness of the helical polymer is addressable by irradiation with two different wavelengths of light. Moreover, we show that the chiral information is transmitted, via the macromolecular level of the polyisocyanate, to the supramolecular level of a lyotropic cholesteric liquid crystalline phase consisting of these stiff, rodlike polymers. This allows the magnitude and sign of the supramolecular helical pitch of the liquid crystal film to be fully controlled by light.

Transmission of Rickettsia raoultii and Rickettsia massiliae DNA by Dermacentor reticulatus and Rhipicephalus sanguineus (s.l.) ticks during artificial feeding

Background: Tick-borne rickettsial pathogens are emerging worldwide and pose an increased health risk to both humans and animals. A plethora of rickettsial species has been identified in ticks recovered from human and animal patients. However, the detection of rickettsial DNA in ticks does not necessarily mean that these ticks can act as vectors for these pathogens. Here, we used artificial feeding of ticks to confirm transmission of Rickettsia massiliae and Rickettsia raoultii by Rhipicephalus sanguineus (sensu lato) and Dermacentor reticulatus ticks, respectively. The speed of transmission was also determined. Methods: An artificial feeding system based on silicone membranes were used to feed adult R. sanguineus (s.l.) and D. reticulatus ticks. Blood samples from in vitro feeding units were analysed for the presence of rickettsial DNA using PCR and reverse line blot hybridisation. Results: The attachment rate of R. sanguineus (s.l.) ticks were 40.4% at 8 h post-application, increasing to 70.2% at 72 h. Rickettsia massiliae was detected in blood samples collected 8 h after the R. sanguineus (s.l.) ticks were placed into the in vitro feeding units. D. reticulatus ticks were pre-fed on sheep and subsequently transferred to the in vitro feeding system. The attachment rate was 29.1 % at 24 h post-application, increasing to 43.6 % at 96 h. Rickettsia raoultii was detected in blood collected 24 h after D. reticulatus was placed into the feeding units. Conclusions: Rhipicephalus sanguineus (s.l.) and D. reticulatus ticks are vectors of R. massiliae and R. raoultii, respectively. The transmission of R. massiliae as early as 8 h after tick attachment emphasises the importance of removing ticks as soon as possible to minimise transmission. This study highlights the relevance of in vitro feeding systems to provide insight into the vectorial capacity of ticks and the dynamics of tick-borne pathogen transmission

Successful Clindamycin Therapy of an Infected Subcutaneous Permanent Pacing Lead in a Dog after a Failed Course with Potentiated Amoxicillin and Enrofloxacin

Though permanent pacemaker implantation is the only effective therapy for certain bradyarrhythmias in dogs, it is not without risks. Bacterial infection of the device is one of the most common complications. Human guidelines recommend besides systemic antibiotics, surgical explantation of the pacing lead and pulse generator in case of device-infection. This report describes a 13.5-year-old dog that received a transvenous endocardial permanent pacemaker because of syncopal episodes resulting from paroxysmal third-degree atrio-ventricular block. Five days after an uneventful surgery, a painful swelling appeared around the subcutaneous part of the lead where this was inserted into the jugular vein. A 4-week course of amoxicillin and clavulanic acid combined with enrofloxacin failed to clear the infection on long-term. Ultrasound-guided puncture of the abscess was performed to gain a sample for bacterial culture and antibiogram. Oral clindamycin of 4 weeks' duration successfully resolved the infection with Staphylococcus aureus without having to explant the device. Repeated ultrasonographic examinations and fine-needle aspiration biopsies were used to evaluate for persistent local inflammation, guiding the length of the antibiotic therapy. Though the described approach has traditionally been ill-advised because of the risk of introducing bacteria and damaging the pacemaker lead, it was successful in our case

Gene silencing in tick cell lines using small interfering or long double-stranded RNA

Gene silencing by RNA interference (RNAi) is an important research tool in many areas of biology. To effectively harness the power of this technique in order to explore tick functional genomics and tick-microorganism interactions, optimised parameters for RNAi-mediated gene silencing in tick cells need to be established. Ten cell lines from four economically important ixodid tick genera (Amblyomma, Hyalomma, Ixodes and Rhipicephalus including the sub-species Boophilus) were used to examine key parameters including small interfering RNA (siRNA), double stranded RNA (dsRNA), transfection reagent and incubation time for silencing virus reporter and endogenous tick genes. Transfection reagents were essential for the uptake of siRNA whereas long dsRNA alone was taken up by most tick cell lines. Significant virus reporter protein knockdown was achieved using either siRNA or dsRNA in all the cell lines tested. Optimum conditions varied according to the cell line. Consistency between replicates and duration of incubation with dsRNA were addressed for two Ixodes scapularis cell lines; IDE8 supported more consistent and effective silencing of the endogenous gene subolesin than ISE6, and highly significant knockdown of the endogenous gene 2I1F6 in IDE8 cells was achieved within 48 h incubation with dsRNA. In summary, this study shows that gene silencing by RNAi in tick cell lines is generally more efficient with dsRNA than with siRNA but results vary between cell lines and optimal parameters need to be determined for each experimental system

Robotic Ultrasound Guidance by B-scan Plane Positioning Control

AbstractUltrasound is indispensable imaging modality for clinical diagnosis such as fetus assessment and heart assessment. Moreover, many ultrasound applications for image guided procedures have been proposed and attempted because US is less invasive, less cost, and high portability. However, to obtain US images, a US imaging probe has to be held manually and contacted with a patient body. To address the issue, we have proposed a robotic system for automatic probe scanning. The system consists of a probe scanning robot, navigation software, an optical tracking device, and an ultrasound imaging device. The robot, that is six degrees of freedom, is composed of a frame mechanism and a probe holding mechanism. The frame mechanism has six pneumatic actuators to reduce its weight, and the probe holding mechanism has one DC motor. The probe holding mechanism is connected with the pneumatic actuators using wires. Moreover, the robot can control the position and orientation of the B-scan plane based on the transformation between an optical tracker attached to the US probe and the B-scan plane. The navigation system, which is connected with the tracking device and an US imaging device via a VGA cable, computes the relative position between the positions of a therapeutic tool and the B-scan plane, and sends it to the robot. Then the position of the B-scan plane can be controlled based on the tool position. Also, the navigation system displays the plane with a texture of an actual echogram and a tool model three-dimensionally to monitor the relative position of the tool and the B-scan plane. To validate the basic system performance, phantom tests were conducted. The phantom was made of gelatin and poly(ethylene glycol). In the tests, the needle was inserted into the phantom, and the B-scan plane was controlled to contain a tracked needle in real-time. From the results, the needle was continuously visualized during needle insertion. Therefore, it is confirmed that the system has a great potential for automatic US image guided procedures

Relationships between renal cytoplasmic and nuclear aldosterone-receptors

Relationships between renal cytoplasmic and nuclear aldosteronereceptors.Three 3H-aldosterone receptor complexes have been recovered from rat kidneys: 1) cytosol (high speed supernatants), 2) Tris-soluble nuclear (obtained by an osmotic shock procedure), and 3) chromatin-bound (prepared by extracting post-shock nuclei with 0.4 M KCl).Glycerol density gradient analyses of cytosol labelled in vivo or in vitro with 3H-aldosterone yielded two specific peaks -4.5S and 8.5S.These peaks were sensitive to salt concentration; 0.4 M KCl shifted the 8.5S to 4.5S and the addition of Ca++ (6 mM) resulted in a further shift to 3.5S.The Tris-soluble nuclear species sedimented at 3S and the chromatin-bound species at 4S.The time-course of generation of the 3H-aldosterone-labelled cytosol and nuclear receptor species was studied in vivo and in vitro by tissue slice and reconstitution methods.The results obtained are consistent with a three-step mechanism: cytosol (8.5S or 4.5S)→ Tris-soluble nuclear (3S)→ chromatin-bound (4S).Alternatively, the 3S and 4S complexes may be attached to independent nuclear sites.The formation of the chromatin-bound species was temperature sensitive and failed to form at 0°C.Pre-treatment with DNase but not RNase impaired the generation of both the Tris-soluble nuclear and chromatin-bound species.These results imply a close association between nuclear aldosterone-receptor complexes and intact DNA

Longitudinal monitoring of Ehrlichia ruminantium infection in Gambian lambs and kids by pCS20 PCR and MAP1-B ELISA

<p>Abstract</p> <p>Background</p> <p>The epidemiology of <it>E. ruminantium </it>infection in extensively managed young animals is not adequately understood. Thus in this study, we monitored the onset (age at first infection) and kinetics of <it>E. ruminantium </it>infection and antibody response in extensively managed newborn lambs and kids at three sites in The Gambia.</p> <p>Methods</p> <p>We used a nested pCS20 PCR and MAP1-B ELISA in a longitudinal study to monitor the onset (age at first infection) and kinetics of <it>E. ruminantium </it>infection and antibody response respectively, in 77 newborn lambs and kids under a traditional husbandry system at three sites (Kerr Seringe, Keneba, Bansang) in The Gambia where heartwater is known to occur. The animals were monitored for field tick infestation and the comparative performance of the two assays in detecting <it>E. ruminantium </it>infection was also assessed.</p> <p>Results</p> <p>The infection rate detected by pCS20 PCR varied between 8.6% and 54.8% over the 162-day study period. Nineteen per cent of the animals in week 1 post-partum tested positive by pCS20 PCR with half of these infections (7/14) detected in the first 3 days after birth, suggesting that transmission other than by tick feeding had played a role. The earliest detectable <it>A. variegatum </it>infestation in the animals occurred in week 16 after birth. Antibodies detected by MAP1-B ELISA also varied, between 11.5% and 90%. Although there is considerable evidence that this assay can detect false positives and due to this and other reasons serology is not a reliable predictor of infection at least for heartwater. In contrast to the pCS20 PCR, the serological assay detected the highest proportion of positive animals in week 1 with a gradual decline in seropositivity with increasing age. The pCS20 PCR detected higher <it>E. ruminantium </it>prevalence in the animals with increasing age and both the Spearman's rank test (<it>r</it>_{<it>s </it>}= -0.1512; P = 0.003) and <it>kappa </it>statistic (-0.091 to 0.223) showed a low degree of agreement between the two assays.</p> <p>Conclusion</p> <p>The use of pCS20 PCR supported by transmission studies and clinical data could provide more accurate information on heartwater epidemiology in endemic areas and single-occasion testing of an animal may not reveal its true infection status. The view is supported because both the vector and vertical transmission may play a vital role in the epidemiology of heartwater in young small ruminants; the age range of 4 and 12 weeks corresponds to the period of increased susceptibility to heartwater in traditionally managed small ruminants.</p

Defining the concept of ‘tick repellency’ in veterinary medicine

Although widely used, the term repellency needs to be employed with care when applied to ticks and other periodic or permanent ectoparasites. Repellency has classically been used to describe the effects of a substance that causes a flying arthropod to make oriented movements away from its source. However, for crawling arthropods such as ticks, the term commonly subsumes a range of effects that include arthropod irritation and consequent avoiding or leaving the host, failing to attach, to bite, or to feed. The objective of the present article is to highlight the need for clarity, to propose consensus descriptions and methods for the evaluation of various effects on ticks caused by chemical substances

Comparison of DNA methylation patterns of parentally imprinted genes in placenta derived from IVF conceptions in two different culture media

Study question: Is there a difference in DNA methylation status of imprinted genes in placentas derived from IVF conceptions where embryo culture was performed in human tubal fluid (HTF) versus G5 culture medium? Summary answer: We found no statistically significant differences in the mean DNA methylation status of differentially methylated regions (DMRs) associated with parentally imprinted genes in placentas derived from IVF conceptions cultured in HTF versus G5 culture medium. What is known already: Animal studies indicate that the embryo culture environment affects the DNA methylation status of the embryo. In humans, birthweight is known to be affected by the type of embryo culture medium used. The effect of embryo culture media on pregnancy, birth and child development may thus be mediated by differential methylation of parentally imprinted genes in the placenta. Study design, size, duration: To identify differential DNA methylation of imprinted genes in human placenta derived from IVF conceptions exposed to HTF or G5 embryo culture medium, placenta samples (n = 43 for HTF, n = 54 for G5) were collected between 2010 and 2012 s as part of a multi-center randomized controlled trial in the Netherlands comparing these embryo culture media. Placenta samples from 69 naturally conceived (NC) live births were collected during 2008-2013 in the Netherlands as reference material. Participants/materials, setting, methods: To identify differential DNA methylation of imprinted genes, we opted for an amplicon-based sequencing strategy on an Illumina MiSeq sequencing platform. DNA was isolated and 34 DMRs associated with well-defined parentally imprinted genes were amplified in a two-step PCR before sequencing using MiSeq technology. Sequencing data were analyzed in a multivariate fashion to eliminate possible confounding effects. Main results and the role of chance: We found no statistically significant differences in the mean DNA methylation status of any of the imprinted DMRs in placentas derived from IVF conceptions cultured in HTF or G5 culture medium. We also did not observe any differences in the mean methylation status per amplicon nor in the variance in methylation per amplicon between the two culture medium groups. A separate surrogate variable analysis also demonstrated that the IVF culture medium was not associated with the DNA methylation status of these DMRs. The mean methylation level and variance per CpG was equal between HTF and G5 placenta. Additional comparison of DNA methylation status of NC placenta samples revealed no statistically significant differences in mean amplicon and CpG methylation between G5, HTF and NC placenta; however, the number of placenta samples exhibiting outlier methylation levels was higher in IVF placenta compared to NC (P < 0.00001). Also, we were able to identify 37 CpG sites that uniquely displayed outlier methylation in G5 placentas and 32 CpG sites that uniquely displayed outlier methylation in HTF. In 8/37 (G5) and 4/32 (HTF) unique outliers CpGs, a medium-specific unique outlier could be directly correlated to outlier methylation of the entire amplicon. Limitations, reasons for caution: Due to practical reasons, not all placentas were collected during the trial, and we collected the placentas from natural conceptions from a different cohort, potentially creating bias. We limited ourselves to the DNA methylation status of 34 imprinted DMRs, and we studied only the placenta and no other embryo-derived tissues. Wider implications of the findings: It has often been postulated, but has yet to be rigorously tested, that imprinting mediates the effects of embryo culture conditions on pregnancy, birth and child development in humans. Since we did not detect any statistically significant effects of embryo culture conditions on methylation status of imprinted genes in the placenta, this suggests that other unexplored mechanisms may underlie these effects. The biological and clinical relevance of detected outliers with respect to methylation levels of CpGs and DMR require additional analysis in a larger sample size as well. Given the importance and the growing number of children born through IVF, research into these molecular mechanisms is urgently needed. Study funding/competing interest(s): This study was funded by the March of Dimes grant number #6-FY13-153. The authors have no conflicts of interest. Trial registration number: Placental biopsies were obtained under Netherlands Trial Registry number 1979 and 1298