Several cell-based biological applications in microfluidic systems require simultaneous high-throughput and individual handling of cells or other bioparticles. Available chip-based tools for contactless manipulation are designed for either high-precision handling of individual particles, or high-throughput handling of ensembles of particles. In order to simultaneously perform both, we have combined two manipulation technologies based on ultrasonic standing waves (USWs) and dielectrophoresis (DEP) in a microfluidic chip. The principle is based on the competition between long-range ultrasonic forces, short-range dielectrophoretic forces and viscous drag forces from the fluid flow. The ultrasound is coupled into the microchannel resonator by an external transducer with a refractive element placed on top of the chip, thereby allowing transmission light microscopy to continuously monitor the biological process. The DEP manipulation is generated by an electric field between co-planar microelectrodes placed on the bottom surface of the fluid channel. We demonstrate flexible and gentle elementary manipulation functions by the use of USWs and linear or curved DEP deflector elements that can be used in high-throughput biotechnology applications of individual cells.
The effect of age on implant fixation in bone is not always considered during the design of preclinical models. The decision on animal's age is often related to practical or historical reasons, which ultimately may affect the reproducibility of results. This study aimed to quantify the effect of age by monitoring the fixation of contrast‐enhanced PEEK screws in rats, hypothesizing that the kinetics of fixation is impaired in older animals but that age effects are less severe than osteoporotic effects. The time course of implant fixation was investigated in healthy rats at 24, 40, and 60 weeks of age; and in ovariectomized rats. Implant fixation was monitored using in‐vivo microCT and dynamic histomorphometry during 1 month. The rats were euthanized 28 days post screw insertion. The data was analyzed both in absolute value and after normalization to baseline bone mass. In absolute terms, greater age had a detrimental effect on bone implant contact, bone fraction, implant stiffness, and bone remodeling but less than ovariectomy. Interestingly, once data was normalized to baseline bone mass this effect disappeared, suggesting that the physiologic response to implant placement was not affected by age. In conclusion, implant fixation kinetics is less affected by age than by baseline bone mass in this rat model. Animals of different ages can therefore be compared but data must be construed relatively to baseline bone mass and not in absolute terms. © 2018 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 9999:1–12, 2018.
Case summary A 10-year-old castrated male domestic shorthair cat was referred for surgical treatment of a left-sided frontal lobe meningioma diagnosed by CT. Clinically, the cat had generalised tonic–clonic seizures, which reduced in frequency after treatment was started with prednisolone. After definition of the anatomical landmarks of the feline skull, a bilateral transfrontal craniotomy allowed en bloc removal of the meningioma. While postoperative recovery was uneventful, right-sided proprioceptive deficits were still present 6 months after surgery. MRI detected a probable meningoencephalocele herniating through the surgical bone defect in the frontal sinus. Because of the mild neurological deficits and good quality of life, the meningoencephalocele was not treated. Thirty-one months after meningioma removal the cat was alive without further neurological progression. Relevance and novel information To our knowledge, this is the first report to describe, in detail, the technique of transfrontal craniotomy in cats. Iatrogenic meningoencephalocele is a complication that has not previously been described after meningioma removal in cats, and should be considered as a potential complication after craniotomy.
Objectives Systemic hypertension (SHT) causes severe target organ damage (TOD) and blood pressure (BP) measurement should be routine in at-risk populations. Fundoscopy is a tool to corroborate acute clinical relevance of high BP results and to decide on immediate therapy. Not every cat with a high BP result can be examined by an ophthalmologist. The study objective was to determine the reliability of fundoscopy in cats with SHT performed by a veterinarian without ophthalmology specialty training. Methods Cats with suspicion of hypertensive TOD or belonging to a risk population for SHT with a first measurement of elevated BP >160 mmHg were enrolled. Indirect ophthalmoscopy was performed by a recent graduate veterinarian followed by a veterinary ophthalmologist. Confirmation of SHT was based on two additional sets of systolic BP measurements >160 mmHg by Doppler sphygmomanometry. Results Thirty-three cats were included. SHT was confirmed in 27 cats. SHT was detected on routine examinations in 12/27 cats; fundoscopic lesions were observed in 9/12 by the non-trained veterinarian and in 11/12 by an ophthalmologist. Nine of 27 cats were neurological patients; fundoscopic lesions were detected in 4/9 by the non-trained veterinarian and in 7/9 by an ophthalmologist. Six of 27 cats were presented for acute blindness; fundus lesions were detected in all six cats by the non-trained veterinarian and ophthalmologist. SHT was not confirmed and fundoscopic lesions were not detected by either examiner in 6/33 cats. Compared with a veterinary ophthalmologist, reliability of detecting fundus abnormalities by the non-trained veterinarian was 72% (13/18) for cats with, and 100% (6/6) for cats without, vision. Conclusions and relevance Fundus examination by a non-specialty trained veterinarian has reasonably high reliability for the detection of ocular TOD. Private practice veterinarians are encouraged to perform an initial fundic examination in suspected hypertensive cats.
Optoacoustic techniques allow imaging of tissue structures with optical contrast and acoustical resolution. This modality is ideal for visualization of blood vessels since haemoglobin is one of the best-absorbing tissue chromophores. It therefore can provide vasculature images with much higher contrast than pure ultrasound. If compared with standard techniques for blood imaging such as Doppler ultrasound, the major advantage of optoacoustic imaging is scalability allowing a resolution down to several m. The availability of biologically conjugated nanoparticles further allows using this technique for molecular imaging where a precise localization of the abundance of biomolecules is desired in 2d and 3d. The strong spectral dependence of blood absorption properties will potentially allow multispectral optoacoustics for investigation of oxygenation level. While the location and size of vessels can be obtained with optoacoustic b-scans, the understanding of the network requ ires 3d data. We propose the use of a stereo-camera in order to track the transducer position for fast and convenient acquisition of 3d optoacoustic data
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