A continuous flow bioreactor system for high-throughput hyperpolarized metabolic flux analysis

Hyperpolarized carbon-13 labeled compounds are increasingly being used in medical MR imaging (MRI) and MR imaging (MRI) and spectroscopy (MRS) research, due to its ability to monitor tissue and cell metabolism in real-time. Although radiological biomarkers are increasingly being considered as clinical indicators, biopsies are still considered the gold standard for a large variety of indications. Bioreactor systems can play an important role in biopsy examinations because of their ability to provide a physiochemical environment that is conducive for therapeutic response monitoring ex vivo. We demonstrate here a proof-of-concept bioreactor and microcoil receive array setup that allows for ex vivo preservation and metabolic NMR spectroscopy on up to three biopsy samples simultaneously, creating an easy-to-use and robust way to simultaneously run multisample carbon-13 hyperpolarization experiments. Experiments using hyperpolarized [1-13C]pyruvate on ML-1 leukemic cells in the bioreactor setup were performed and the kinetic pyruvate-to-lactate rate constants ( k PL ) extracted. The coefficient of variation of the experimentally found k PL s for five repeated experiments was C V = 35 % . With this statistical power, treatment effects of 30%-40% change in lactate production could be easily differentiable with only a few hyperpolarization dissolutions on this setup. Furthermore, longitudinal experiments showed preservation of ML-1 cells in the bioreactor setup for at least 6 h. Rat brain tissue slices were also seen to be preserved within the bioreactor for at least 1 h. This validation serves as the basis for further optimization and upscaling of the setup, which undoubtedly has huge potential in high-throughput studies with various biomarkers and tissue types.

A roadmap to high-resolution standard microcoil MAS NMR spectroscopy for metabolomics

Current microcoil probe technology has emerged as a significant advancement in NMR applications to biofluids research. It has continued to excel as a hyphenated tool with other prominent microdevices, opening many new possibilities in multiple omics fields. However, this does not hold for biological samples such as intact tissue or organisms, due to the considerable challenges of incorporating the microcoil in a magic-angle spinning (MAS) probe without relinquishing the high-resolution spectral data. Not until 2012 did a microcoil MAS probe show promise in profiling the metabolome in a submilligram tissue biopsy with spectral resolution on par with conventional high-resolution MAS (HR-MAS) NMR. This result subsequently triggered a great interest in the possibility of NMR analysis with microgram tissues and striving toward the probe development of "high-resolution" capable microcoil MAS NMR spectroscopy. This review gives an overview of the issues and challenges in the probe development and summarizes the advancements toward metabolomics.

Canadian Association of Radiologists/Canadian Association of Interventional Radiologists/Canadian Society of Thoracic Radiology Guidelines on Thoracic Interventions

Thoracic interventions are frequently performed by radiologists, but guidelines on appropriateness criteria and technical considerations to ensure patient safety regarding such interventions is lacking. These guidelines, developed by the Canadian Association of Radiologists, Canadian Association of Interventional Radiologists and Canadian Society of Thoracic Radiology focus on the interventions commonly performed by thoracic radiologists. They provide evidence-based recommendations and expert consensus informed best practices for patient preparation; biopsies of the lung, mediastinum, pleura and chest wall; thoracentesis; pre-operative lung nodule localization; and potential complications and their management.

Strength-frequency curve for micromagnetic neurostimulation through excitatory postsynaptic potentials (EPSPs) on rat hippocampal neurons and numerical modeling of magnetic microcoil (μcoil)

OBJECTIVE

The objective of this study was to measure the effect of micromagnetic stimulation (μMS) on hippocampal neurons, by using single microcoil (μcoil) prototype, Magnetic Pen (MagPen). MagPen will be used to stimulate the CA3 magnetically and excitatory post synaptic potential (EPSP) measurements will be made from the CA1. The threshold for μMS as a function of stimulation frequency of the current driving the µcoil will be demonstrated. Finally, the optimal stimulation frequency of the current driving the μcoil to minimize power will be estimated.

APPROACH

A biocompatible prototype, MagPen was built, and customized such that it is easy to adjust the orientation of the μcoil over the hippocampal tissue in an in vitro setting. Finite element modeling (FEM) of the μcoil was performed to estimate the spatial profiles of the magnetic flux density (in T) and the induced electric fields (in V/m). The induced electric field profiles generated at different values of current applied to the µcoil whether can elicit a neuron response was validated by numerical modeling. The modeling settings were replicated in experiments on rat hippocampal neurons.

MAIN RESULTS

The preferred orientation of MagPen over the Schaffer Collateral fibers was demonstrated such that they elicit a neuron response. The recorded EPSPs from CA1 due to μMS at CA3 were validated by applying tetrodotoxin (TTX). Finally, it was interpreted through numerical analysis that increasing frequency of the current driving the μcoil, led to a decrease in the current amplitude threshold for μMS.

SIGNIFICANCE

This work reports that μMS can be used to evoke population EPSPs in the CA1 of hippocampus. It demonstrates the strength-frequency curve for µMS and its unique features related to orientation dependence of the µcoils, spatial selectivity and distance dependence. Finally, the challenges related to µMS experiments were studied including ways to overcome them.

Characterization and Miniaturization of Silver-Nanoparticle Microcoil via Aerosol Jet Printing Techniques for Micromagnetic Cochlear Stimulation

According to the National Institute of Deafness and other Communication Disorders 2012 report, the number of cochlear implant (CI) users is steadily increasing from 324,000 CI users worldwide. The cochlea, located in the inner ear, is a snail-like structure that exhibits a tonotopic geometry where acoustic waves are filtered spatially according to frequency. Throughout the cochlea, there exist hair cells that transduce sensed acoustic waves into an electrical signal that is carried by the auditory nerve to ultimately reach the auditory cortex of the brain. A cochlear implant bridges the gap if non-functional hair cells are present. Conventional CIs directly inject an electrical current into surrounding tissue via an implanted electrode array and exploit the frequency-to-place mapping of the cochlea. However, the current is dispersed in perilymph, a conductive bodily fluid within the cochlea, causing a spread of excitation. Magnetic fields are more impervious to the effects of the cochlear environment due to the material properties of perilymph and surrounding tissue, demonstrating potential to improve precision. As an alternative to conventional CI electrodes, the development and miniaturization of microcoils intended for micromagnetic stimulation of intracochlear neural elements is described. As a step toward realizing a microcoil array sized for cochlear implantation, human-sized coils were prototyped via aerosol jet printing. The batch reproducible aerosol jet printed microcoils have a diameter of 1800 μm, trace width and trace spacing of 112.5 μm, 12 μm thickness, and inductance values of approximately 15.5 nH. Modelling results indicate that the coils have a combined depolarization–hyperpolarization region that spans 1.5 mm and produce a more restrictive spread of activation when compared with conventional CI.

Heterogeneous Disease Progression in a Mouse Model of Vascular Cognitive Impairment

Recently, an asymmetric vascular compromise approach that replicates many aspects of human vascular cognitive impairment (VCI) has been reported. The present study aimed to first investigate on the reproducibility in the disease progression of this newly reported VCI model using wild-type C57BL6/J mice. The second aim was to assess how this approach will affect the disease progression of transgenic Alzheimer’s disease (AD) 5XFAD mice subjected to VCI. C57BL6/J and 5XFAD mice were subjected to VCI by placing an ameroid constrictor on the right CCA and a microcoil on the left CCA. Infarcts and hippocampal neuronal loss did not appear predominantly in the right (ameroid side) as expected but randomly in both hemispheres. The mortality rate of C57BL6/J mice was unexpectedly high. Inducing VCI reduced amyloid burden in the hippocampi of 5XFAD mice. Since VCI is known to be complex and complicated, the heterogeneous disease progression observed from this current study shares close resemblance to the clinical manifestation of VCI. This heterogeneity, however, makes it challenging to test novel treatment options using this model. Further study is warranted to tackle the heterogeneous nature of VCI.

Protocol for the VAL-MAP 2.0 trial: a multicentre, single-arm, phase III trial to evaluate the effectiveness of virtual-assisted lung mapping by bronchoscopic dye injection and microcoil implementation in patients with small pulmonary nodules in Japan

INTRODUCTION

Tumour localisation is important for successful resection of lung nodules with optimal resection margins in sublobar resection. Virtual-assisted bronchoscopic localisation technique combined with dye marking and microcoil placement (VAL-MAP 2.0) is a minimally invasive, virtual-assisted, bronchoscopic technique that combines dye marking and microcoil implementation. As indwelling microcoils can provide information on the depth from the lung surface, they can be applied for deeply located small lung tumours that are barely identifiable by surface dye marking. This proposed study will examine the effectiveness of VAL-MAP 2.0 in patients with small pulmonary nodules.

METHODS AND ANALYSIS

This is a multicentre, prospective, single-arm, clinical trial. A total of 65 patients will be registered to undergo VAL-MAP 2.0 followed by thoracoscopic surgery. The primary outcome is successful resection, defined as resection of the lesion with optimal resection margins. The goal of the study is the achievement of a successful resection rate of 80%.

ETHICS AND DISSEMINATION

The study was approved by the Clinical Research Review Boards of the University of Tokyo (approval number 218 003SP) for all institutes, and the Technical Review Board for Advanced Medicine Category B of the Ministry of Health, Labour and Welfare. Results of the primary and secondary endpoints will be submitted for publication in a peer-reviewed journal.

TRIAL REGISTRATION NUMBER

jRCTs031180099.

Individualized Strategies for Intraoperative Localization of Non-palpable Pulmonary Nodules in a Hybrid Operating Room

Background: Precise preoperative localization of small pulmonary nodules is a key prerequisite to their successful excision. With the advent of hybrid operating rooms (HORs), a patient-tailored approach encompassing simultaneous localization and removal of small pulmonary nodules has become feasible. In this study, we describe our individualized image-guided video assisted thoracoscopic surgery (iVATS) strategies implemented within a HOR environment. Specifically, localization was performed through different marking approaches (single- vs. double-marker) and access routes [percutaneous technique with Dyna-computed tomography (DynaCT) imaging vs. electromagnetic navigation bronchoscopy (ENB)]. Methods: Between April 2017 and November 2018, a total of 159 consecutive patients (harboring 174 pulmonary nodules) were treated with iVATS. The marking approach and access route were individually tailored according to lesion localization and its distance from the pleural surface. The efficacy and safety of our iVATS technique were determined through a retrospective review of clinical charts. Results: All of the localization procedures were performed in a HOR by a single team of thoracic surgeons. The mean tumor size on preoperative CT was 8.28 mm (95% confidence interval [CI]: 7.6-8.96 mm), whereas their mean distance from the pleural surface was 9.44 mm (95% CI: 8.11-10.77 mm). Of the 174 tumors, 150 were localized through a percutaneous DynaCT-guided approach (single-marker: 139, dual-marker: 11), whereas localization in the remaining 24 was accomplished via the ENB-guided approach (single-marker: 4; dual-marker: 20). The mean localization time was 17.78 min (95% CI:16.17-19.39 min). The overall localization success rate was 95.9%. We failed to localize a total of seven nodules either because of technical complications (pneumothorax, n = 3; microcoil dislodgement; n = 1) or machine failure (n = 3). No operative deaths were observed, and the mean length of postoperative stay was 3.65 days (95% CI: 3.19-4.11 days). Conclusions: The use of tailored marking approaches and access routes allowed us to individualize the iVATS procedure for small pulmonary nodules, ultimately promoting a more patient-centered workflow.

Intraoperative Percutaneous Microcoil Localization of Small Peripheral Pulmonary Nodules Using Cone-Beam CT in a Hybrid Operating Room

OBJECTIVE. Thoracoscopic surgical resection of small peripheral pulmonary nodules can be challenging, and often preoperative localization techniques are needed to avoid conversion to open thoracotomy. In this article, we show the feasibility and benefits of performing intraoperative percutaneous microcoil localization with C-arm cone-beam CT in a hybrid operating room immediately before video-assisted thoracoscopic surgery for wedge resection of a small pulmonary nodule. CONCLUSION. This technique can provide safe and accurate localization while minimizing patient discomfort and thus enhancing the patient's experience.

Discussion on operative skills in the embolization of hydrosalpinx by hysteroscopic placement of a microcoil

This study aims to discuss the operative skills of hysteroscopic tubal embolization and reduce the occurrence of complications.Ninety-four patients were divided into group A and group B. The main surgical technique in group A: when the inner sleeve is sent to the fallopian tube and no longer accessible (but no >3 cm), remove the guide wire and put into the microcoil. But in group B, there are four major surgical techniques. First, the depth at which the guide wire enters the tube was controlled at 2 cm. Second, the inner diameter of the fallopian tube must be explored to determine the type and shape of the coils. Third, saline should be used to separate the catheter. Fourth, it is to control the release speed of the coils. The superiority of the improved operation method was confirmed by comparing the surgical failure rate, incidence of complications, and cost of surgery before and after the procedure.The reoperation rate of group A was 10% (3/30), while that of group B was 2.68% (3/112). The ectopic microcoils rate of group A was 6.67% (2/30), while that of group B was 0.89% (1/112). The microcoil damages rate of group 23.33% (7/30), while that of group B was 8.04% (9/112). All P values were <.01, and the difference was statistically significant.Hysteroscopic tubal embolization is currently a new surgical procedure to block the fallopian tubes and prevent the reverse flow of fluid in the fallopian tubes into the uterine cavity. After we improved surgical techniques, the surgical failure rate, complication rate, and operation cost of fallopian tube embolization were significantly lower than before the improved method was applied. The improved techniques led to a higher success rate.

Effect of interventional embolization treatment for hydrosalpinx on the outcome of in vitro fertilization and embryo transfer

To explore the effect of interventional embolization treatment for hydrosalpinx on the outcome of in vitro fertilization and embryo transfer (IVF-ET).During the period from January 2013 to January 2015, a total of 129 patients with unilateral or bilateral hydrosalpinx were treated with IVF-ET and selected for retrospective analysis. Seventy-three patients (intervention group) with unilateral or bilateral hydrosalpinx were treated with fallopian tube embolization, which was followed by IVF-ET. During the same period, 56 patients (control group) with unilateral or bilateral hydrosalpinx directly received IVF-ET without receiving any treatment for hydrosalpinx.The clinical pregnancy rate of the control group was significantly lower than that of the intervention group (P < .05), while the abortion rate and ectopic pregnancy rate of the control group were strikingly higher than that of the intervention group (P < .05).Hydrosalpinx can decrease the clinical pregnancy rate of IVF-ET, and increase the incidence of abortion and ectopic pregnancy. The interventional embolization treatment for hydrosalpinx before IVF-ET can improve the clinical pregnancy rate and reduce adverse pregnancy outcome and which, with the advantages of a high success rate, convenient use, low cost, less pain, no anesthetic risk and no effect on the ovarian function it may further be developed for use in the clinic.

Value of virtual monochromatic spectral images with metal artifact reduction algorithm in dual-energy computed tomography-guided microcoil localization of pulmonary nodules

To evaluate the clinical value of virtual monochromatic spectral (VMS) images with metal artifact reduction (MAR) algorithm in dual-energy computed tomography (DECT)-guided microcoil localization of pulmonary nodules.Fifty-one patients underwent DECT after placement of microcoils on small pulmonary nodules before video-assisted thoracoscopic surgery (VATS). Optimal energy level (in keV) was defined as the level at which CT values of nodules were equivalent to those of 120 kVp images and with no serious metal artifacts. VMS images at optimal keV and at 50, 90,110, and 140 keV with and without MAR were reconstructed. Image quality was scored using a 3-point scale: 1 = excellent, minimal artifacts; 2 = good, mild artifacts; and 3 = poor, extensive artifacts. Image quality scores between the VMS-only and VMS + MAR groups were compared;74 keV was found to be the optimal level for VMS images. The image quality of the VMS + MAR images at 74 keV were significantly better than VMS-only images (1.35 ± 0.59 vs 2.11 ± 0.87, P = .005). There was no difference in image quality score among VMS + MAR images at 74 keV and higher energy levels.VMS images from DECT at 74 keV with MAR can reduce artifacts from microcoils and improve image quality for microcoil localization of pulmonary nodules.

High-resolution computed tomography features and CT-guided microcoil localization of subcentimeter pulmonary ground-glass opacities: radiological processing prior to video-assisted thoracoscopic surgery

Background

With the rapid development of high-resolution computed tomography (HRCT), low-dose CT scanning and video-assisted thoracoscopic surgery (VATS), smaller pulmonary nodules can be detected. Subcentimeter ground-glass opacities (GGOs) are extremely difficult to diagnose and accurately locate during VATS and in surgically resected specimens.

Methods

From September 2013 to September 2017, 42 subcentimeter GGO lesions (≤1 cm) in 31 patients who underwent CT-guided microcoil insertion followed by VATS resection were included. All HRCT images were assessed by two experienced radiologists, and CT-guided microcoil localization procedures were performed by two experienced interventional radiologists.

Results

A total of 42 subcentimeter GGOs included 28 malignancies (66.7%) and 14 benign lesions (33.3%). The diameter of malignant GGOs (8.52±1.46 mm) was significantly larger than that of benign lesions (7.04±1.52 mm) (P<0.05). Seven patients had more than one GGO nodule. There were no significant differences in the location, composition, shape, margins, presence of air bronchograms, presence of the pleural indentation sign and presence of the vascular convergence sign between benign and malignant GGOs (P>0.05). All the localization procedures were performed successfully. A small pneumothorax occurred in 9 patients (21.4%), and minor hemorrhage in the lung parenchyma occurred in 8 patients (19.0%). All GGOs were easily identified during VATS and were definitively diagnosed.

Conclusions

Common HRCT features cannot be used as criteria for the differential diagnosis of subcentimeter benign and malignant pulmonary GGOs. CT-guided microcoil marking of these lesions prior to VATS is a feasible, safe, and effective procedure for the localization of subcentimeter pulmonary GGOs.

Online 1 H-MRS measurements of time-varying lactate production in an animal model of glioma during administration of an anti-tumoral drug

The aims of this study were to implement a magnetic resonance spectroscopy (MRS) protocol for the online profiling of subnanomolar quantities of metabolites sampled from the extracellular fluid using implanted microdialysis and to apply this protocol in glioma-bearing rats for the quantification of lactate concentration and the measurement of time-varying lactate concentration during drug administration. MRS acquisitions on the brain microdialysate were performed using a home-built, proton-tuned, microsolenoid with an active volume of 2 μL. The microcoil was placed at the outlet of the microdialysis probe inside a preclinical magnetic resonance imaging (MRI) scanner. C6-bearing rats were implanted with microdialysis probes perfused with artificial cerebrospinal fluid solution and the lactate dehydrogenase (LDH) inhibitor oxamate. Microcoil magnetic resonance spectra were continuously updated using a single-pulse sequence. Localized in vivo spectra and high-resolution spectra on the dialysate were also acquired. The limit of detection and limit of quantification per unit time of the lactate methyl peak were determined as 0.37 nmol/√min and 1.23 nmol/√min, respectively. Signal-to-noise ratios (SNRs) of the lactate methyl peak above 120 were obtained from brain tumor microdialysate in an acquisition time of 4 min. On average, the lactate methyl peak amplitude measured in vivo using the nuclear magnetic resonance (NMR) microcoil was 193 ± 46% higher in tumor dialysate relative to healthy brain dialysate. A similar ratio was obtained from high-resolution NMR spectra performed on the collected dialysate. Following oxamate addition in the perfusate, a monotonic decrease in the lactate peaks was observed in all animals with an average time constant of 4.6 min. In the absence of overlapping NMR peaks, robust profiling of extracellular lactate can be obtained online using a dedicated sensitive NMR microcoil. MRS measurements of the dynamic changes in lactate production induced by anti-tumoral drugs can be assessed accurately with temporal resolutions on the order of minutes. The MRS protocol can be readily transferred to the clinical environment with the use of suitable clinical microdialysis probes.

A Sub-millimeter, Inductively Powered Neural Stimulator

Wireless neural stimulators are being developed to address problems associated with traditional lead-based implants. However, designing wireless stimulators on the sub-millimeter scale (<1 mm³) is challenging. As device size shrinks, it becomes difficult to deliver sufficient wireless power to operate the device. Here, we present a sub-millimeter, inductively powered neural stimulator consisting only of a coil to receive power, a capacitor to tune the resonant frequency of the receiver, and a diode to rectify the radio-frequency signal to produce neural excitation. By replacing any complex receiver circuitry with a simple rectifier, we have reduced the required voltage levels that are needed to operate the device from 0.5 to 1 V (e.g., for CMOS) to ~0.25–0.5 V. This reduced voltage allows the use of smaller receive antennas for power, resulting in a device volume of 0.3–0.5 mm³. The device was encapsulated in epoxy, and successfully passed accelerated lifetime tests in 80°C saline for 2 weeks. We demonstrate a basic proof-of-concept using stimulation with tens of microamps of current delivered to the sciatic nerve in rat to produce a motor response.

A novel hybrid technique for localization of subcentimeter lung nodules

BACKGROUND

It is technically challenging to locate non-visible, non-palpable subcentimeter ground-glass nodules (GGNs) of lung during video-assisted thoracic surgery (VATS). Computed tomography (CT)-guided marking of small pulmonary nodules using microcoils has been reported to be a practical method of preoperative localization, whereas dislodgement of microcoils remains to be a bothersome complication. The objective of this study was to assess the viability and effectiveness of a newly developed hybrid technique, which combines induced controllable pneumothorax and CT-guided microcoil marking procedure to reduce the risk of microcoil dislodgement.

METHODS

After induced minor pneumothorax, 35 patients with subcentimeter GGNs underwent CT-guided marking with microcoils prior to VATS sublobar resection or lobectomy. Histopathological analysis was performed after surgeries.

RESULTS

All of 37 nodules were successfully marked before VATS. Segmentectomy was performed in 8 cases, wedge resection in 19 cases and lobectomy in 8 cases. All nodules were completely removed with marking microcoils. Dislodgement of microcoils was not observed in all cases and mild pulmonary hemorrhage occurred in one case. No other complications occurred.

CONCLUSIONS

The newly developed hybrid technique which combines induced controllable pneumothorax and CT-guided marking using microcoils was feasible and reliable for VATS resection of subcentimeter GGNs, meanwhile significantly lowered the risk of microcoil dislocation.

NMR reaction monitoring in flow synthesis

Recent advances in the use of flow chemistry with in-line and on-line analysis by NMR are presented. The use of macro- and microreactors, coupled with standard and custom made NMR probes involving microcoils, incorporated into high resolution and benchtop NMR instruments is reviewed. Some recent selected applications have been collected, including synthetic applications, the determination of the kinetic and thermodynamic parameters and reaction optimization, even in single experiments and on the μL scale. Finally, software that allows automatic reaction monitoring and optimization is discussed.

Remarkable Conductive Anisotropy of Metallic Microcoil/PDMS Composites Made by Electric Field Induced Alignment

We successfully fabricated a highly anisotropic electrical conductive microcoil/polydimethylsiloxane (PDMS) composite based on helical Spirulina-templated metallic particles using an electric field-induced alignment method. The optimized AC electric field (2 kV/cm, 1 kHz) could efficiently assemble the lightweight conductive microcoils into continuous long chains and form unique end-to-end physical contacts between adjacent particles in the alignment direction, leading to highly conductive channels. Furthermore, the electrical conductivity in the alignment direction reached up to ∼10 S/m for 1 wt % loading and exhibited almost 7-8 orders of magnitude higher than that in perpendicular directions, which is by far the most remarkable conductive anisotropy for anisotropic conductive composites (ACCs). In addition, the anisotropic composites exhibit excellent current-carrying capability in a functional light emitting diode (LED) circuit. Therefore, due to the superior conductive anisotropy and high conductivity, the composites have promising potential in high reliability electrical interconnections and subminiature integrated circuits.

Polymer Magnetic Composite Core Based Microcoils and Microtransformers for Very High Frequency Power Applications

We present a rapid prototyping and a cost effective fabrication process on batch fabricated wafer-level micro inductive components with polymer magnetic composite (PMC) cores. The new PMC cores provide a possibility to bridge the gap between the non-magnetic and magnetic core inductive devices in terms of both the operating frequency and electrical performance. An optimized fabrication process of molding, casting, and demolding which uses teflon for the molding tool is presented. High permeability NiFeZn powder was mixed with Araldite epoxy to form high resistive PMC cores. Cylindrical PMC cores having a footprint of 0.79 mm2 were fabricated with varying percentage of the magnetic powder on FR4 substrates. The core influence on the electrical performance of the inductive elements is discussed. Inductor chips having a solenoidal coil as well as transformer chips with primary and secondary coils wound around each other have been fabricated and evaluated. A core with 65% powder equipped with a solenoid made out of 25 µm thick insulated Au wire having 30 turns, yielded a constant inductance value of 2 µH up to the frequency of 50 MHz and a peak quality factor of 13. A 1:1 transformer with similar PMC core and solenoidal coils having 10 turns yielded a maximum efficiency of 84% and a coupling factor of 96%. In order to protect the solenoids and to increase the mechanical robustness and handling of the chips, a novel process was developed to encapsulate the components with an epoxy based magnetic composite. The effect on the electrical performance through the magnetic composite encapsulation is reported as well.

A Differential Monolithically Integrated Inductive Linear Displacement Measurement Microsystem

An inductive linear displacement measurement microsystem realized as a monolithic Application-Specific Integrated Circuit (ASIC) is presented. The system comprises integrated microtransformers as sensing elements, and analog front-end electronics for signal processing and demodulation, both jointly fabricated in a conventional commercially available four-metal 350-nm CMOS process. The key novelty of the presented system is its full integration, straightforward fabrication, and ease of application, requiring no external light or magnetic field source. Such systems therefore have the possibility of substituting certain conventional position encoder types. The microtransformers are excited by an AC signal in MHz range. The displacement information is modulated into the AC signal by a metal grating scale placed over the microsystem, employing a differential measurement principle. Homodyne mixing is used for the demodulation of the scale displacement information, returned by the ASIC as a DC signal in two quadrature channels allowing the determination of linear position of the target scale. The microsystem design, simulations, and characterization are presented. Various system operating conditions such as frequency, phase, target scale material and distance have been experimentally evaluated. The best results have been achieved at 4 MHz, demonstrating a linear resolution of 20 µm with steel and copper scale, having respective sensitivities of 0.71 V/mm and 0.99 V/mm.

[Masywne krwawienie z jelita małego: nowa opcja terapeutyczna z lokalizacją microcoil i laparoskopową resekcją]

Masywne krwawienie z przewodu pokarmowego prezentuje kompleksowy problem diagnostyczny i terapeutyczny. Dokładna identyfikacja miejsca krwawienia jest skomplikowana i chirurgiczna resekcja miejsca krwawienia jest trudne. Angiografii używanej do lokalizacji i embolizacji miejscu krwawienia w krążeniu krezkowym brakuje skuteczności ze względu na skomplikowaną sieć zespolenia naczyń krwionośnych zaopatrujących jelito cienkie. Przedoperacyjnie umieszczenie microcoil dla fluoroskopowo kierowanej laparoskopowej resekcji jelita cienkiego zostało wykorzystane w przypadku 58-letniej kobiety leczonej chemioterapią z użyciem idarubicyny i cytarabiny. Pacjentka miała krwawienie z przewodu pokarmowego, ktore nie reagowało na leczenie zachowawcze i wymagało masywnych transfuzji produktow krwi.

A more consistent intraluminal rhesus monkey model of ischemic stroke

Endovascular surgery is advantageous in experimentally induced ischemic stroke because it causes fewer cranial traumatic lesions than invasive surgery and can closely mimic the pathophysiology in stroke patients. However, the outcomes are highly variable, which limits the accuracy of evaluations of ischemic stroke studies. In this study, eight healthy adult rhesus monkeys were randomized into two groups with four monkeys in each group: middle cerebral artery occlusion at origin segment (M1) and middle cerebral artery occlusion at M2 segment. The blood flow in the middle cerebral artery was blocked completely for 2 hours using the endovascular microcoil placement technique (1 mm × 10 cm) (undetachable), to establish a model of cerebral ischemia. The microcoil was withdrawn and the middle cerebral artery blood flow was restored. A reversible middle cerebral artery occlusion model was identified by hematoxylin-eosin staining, digital subtraction angiography, magnetic resonance angiography, magnetic resonance imaging, and neurological evaluation. The results showed that the middle cerebral artery occlusion model was successfully established in eight adult healthy rhesus monkeys, and ischemic lesions were apparent in the brain tissue of rhesus monkeys at 24 hours after occlusion. The rhesus monkeys had symptoms of neurological deficits. Compared with the M1 occlusion group, the M2 occlusion group had lower infarction volume and higher neurological scores. These experimental findings indicate that reversible middle cerebral artery occlusion can be produced with the endovascular microcoil technique in rhesus monkeys. The M2 occluded model had less infarction and less neurological impairment, which offers the potential for application in the field of brain injury research.

Nuclear magnetic resonance at the picomole level of a DNA adduct

We investigate the limit of detection for obtaining NMR data of a DNA adduct using modern microscale NMR instrumentation, once the adduct has been isolated at the picomole level. Eighty nanograms (130 pmol) of a DNA adduct standard, N-(2'-deoxyguanosin-8-yl)-2-acetylaminofluorene 5'-monophosphate (AAF-dGMP), in 1.5 μL of D₂O with 10% methanol-d₄, in a vial, was completely picked up as a droplet suspended in a fluorocarbon liquid and loaded efficiently into a microcoil probe. This work demonstrates a practical manual method of droplet microfluidic sample loading, previously demonstrated using automated equipment, which provides a severalfold advantage over conventional flow injection. Eliminating dilution during injection and confining the sample to the observed volume produce the full theoretical mass sensitivity of a microcoil, comparable to that of a microcryo probe. With 80 ng, an NMR spectrum acquired over 40 h showed all of the resonances seen in a standard spectrum of AAF-dGMP, with a signal-to-noise ratio of at least 10, despite broadening due to previously noted effects of conformational exchange. Even with this broadening to 5 Hz, a two-dimensional total correlation spectroscopy spectrum was acquired on 1.6 μg in 18 h. This work helps to define the utility of NMR in combination with other analytical methods for the structural characterization of a small amount of a DNA adduct.

Susceptibility-matched plugs for microcoil NMR probes

For mass-limited samples, the residual sample volume outside the detection coil is an important concern, as is good base line resolution. Here, we present the construction and evaluation of magnetic susceptibility-matched plugs for microcoil NMR sample cells which address these issues. Mixed-epoxy glue and ultem tube plugs that have susceptibility values close to those of perfluorocarbon FC-43 (fluorinert) and copper were used in small volume (0.5-2 microL) and larger volume (15-20 microL) thin glass capillary sample cells. Using these plugs, the sample volume efficiency (i.e. ratio of active volume to total sample volume in the microcoil NMR cell) was improved by 6-12-fold without sensitivity and resolution trade-offs. Comparison with laser etched or heat etched microcoil sample cells is provided. The approaches described are potentially useful in metabolomics for biomarkers detection in mass limited biological samples.

New Solenoidal Microcoil NMR Probe Using Zero-Susceptibility Wire

We present the construction and performance of a 20-μL active volume probe that utilizes zero-susceptibility wire for the detection transceiver coil and a 3.5 mm outer diameter thin-wall bubble flow cell to contain the sample. The probe shows good rf homogeneity, resolution, line shape and sensitivity. The sensitivity and resolution of the 20-μL probe was compared to those for several other coil configurations, including smaller detection volumes, a thin wire copper coil immersed in susceptibility matching perfluorocarbon FC-43 (fluorinert) fluid, and a standard 5 mm probe. In particular, the (1)H mass sensitivity, S(m) (SNR per micromole), was 3-4 fold higher than that for the standard 5 mm probe. Finally, the use of the zero-susceptibility wire in smaller volume probes is discussed along with potential future improvements and applications.

Design and construction of a versatile dual volume heteronuclear double resonance microcoil NMR probe

Improved NMR detection of mass limited samples can be obtained by taking advantage of the mass sensitivity of microcoil NMR, while throughput issues can be addressed using multiple, parallel sample detection coils. We present the design and construction of a double resonance 300-MHz dual volume microcoil NMR probe with thermally etched 440-nL detection volumes and fused silica transfer lines for high-throughput stopped-flow or flow-through sample analysis. Two orthogonal solenoidal detection coils and the novel use of shielded inductors allowed the construction of a probe with negligible radio-frequency cross talk. The probe was resonated at (1)H-(2)D (upper coil) and (1)H-(13)C (lower coil) frequencies such that it could perform 1D and 2D experiments with active locking frequency. The coils exhibited line widths of 0.8-1.1 Hz with good mass sensitivity for both (1)H and (13)C NMR detection. (13)C-directly detected (2)D HETCOR spectra of 5% v/v (13)C labeled acetic acid were obtained in less than 5 min. Demonstration of the probe characteristics as well as applications of the versatile two-coil double resonance probe are discussed.