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1.
Tissue Eng Part A ; 28(3-4): 175-183, 2022 02.
Article in English | MEDLINE | ID: mdl-34309434

ABSTRACT

Postsurgical infections of the shoulder joint involving Cutibacterium acnes are difficult to diagnose and manage. Despite the devastating clinical complications and costly health care burden of joint infections, the scarcity of joint infection models was identified as an unmet need by the 2019 International Consensus on Orthopedic Infections. In this study, we have developed a novel 3D shoulder joint implant mimetic (S-JIM) that includes a surgical metal surface and supports a co-culture of C. acnes and patient-derived shoulder capsule fibroblasts. Our findings indicate the S-JIM can generate a near anaerobic interior environment that allows for C. acnes proliferation and elicits fibroblast cell lysis responses that are consistent with clinical reports of tissue necrosis. Using the S-JIM, we have provided proof-of-concept for the use of mass spectrometry in real-time detection of C. acnes joint infections during surgery. The S-JIM is the first in vitro cell culture-based biomimetic of periprosthetic joint infection (PJI) that provides a preclinical method for the rapid and reliable testing of novel anti-PJI interventions. Impact statement We have developed the first 3D laboratory biomimetic of the postsurgical human shoulder joint to study periprosthetic joint infections.


Subject(s)
Arthroplasty, Replacement, Shoulder , Prosthesis-Related Infections , Shoulder Joint , Biomimetics , Humans , Propionibacterium acnes , Prosthesis-Related Infections/diagnosis , Prosthesis-Related Infections/microbiology , Prosthesis-Related Infections/surgery , Shoulder Joint/surgery
2.
Intensive Care Med Exp ; 6(1): 45, 2018 Nov 01.
Article in English | MEDLINE | ID: mdl-30387029

ABSTRACT

BACKGROUND: Selective brain cooling (SBC) methods could alleviate the complications associated with systemic hypothermia. The authors (MFB, LK, and T-YL) have developed a simple and an effective nasopharyngeal SBC method using a vortex tube. The primary focus of the study is to evaluate the effectiveness of this approach on rabbits and compare it with our previous published finding on piglets, which are mammals without and with a carotid rete, respectively. METHODS: Experiments were conducted on six rabbits. Body temperature was measured continuously using an esophageal temperature probe while brain temperature was measured with an implanted thermometer. Two successive experiments were performed on each animal. In the first experiment, brain cooling was initiated by blowing room temperature air from the hospital medical air outlet, at a flow rate of 14-15 L/min into both nostrils for 60 min. The second series of measurements and brain cooling was performed in the same manner as the first one but blowing cold air (- 7 °C) at the same flow rate. RESULTS: One hour post cooling with room temperature air at a flow rate of 14-15 L/min, the brain temperature was 34.2 ± 1.2 °C which resulted in mean brain cooling rates of 3.7 ± 0.9 °C/h. Brain temperature could be reduced more rapidly at mean rates of 5.2 ± 1.9 °C/h, while the body temperature as measured by the esophageal temperature probe was maintained above 36 °C during cooling and maintaining period. CONCLUSIONS: We have demonstrated that using the vortex tube allows initial rapid and SBC in rabbits. Moreover, comparing results between piglets and rabbits demonstrates clearly that the lack of a carotid rete does not prevent specific cooling of the brain by means of the nasopharyngeal method.

3.
Intensive Care Med Exp ; 4(1): 32, 2016 Dec.
Article in English | MEDLINE | ID: mdl-27686339

ABSTRACT

BACKGROUND: Target temperature management is the single most effective intervention and the gold standard in post-resuscitation care today. However, cooling the whole body below 33-34 °C can cause severe complications. Therefore, developing a selective brain cooling (SBC) approach which can be initiated early to induce rapid cooling and maintain the target temperature over 12-24 h before slowly rewarming brain temperature by itself alone would be advantageous. Vortex tubes are simple mechanical devices generating cold air from a stream of compressed air without applied chemical or energy. This study investigated whether blowing cooled air from a vortex tube into the nasal cavities is safe and effective to selectively reduce and maintain before slowly rewarming brain temperature back to normal temperature. METHODS: Experiments were conducted on ten juvenile pigs. Body temperature was measured using an esophageal and a rectal temperature probe while brain temperature with an intraparenchymal thermocouple probe. Cerebral blood flow (CBF) was measured with CT perfusion. RESULTS: Brain temperature dropped below 34 °C within 30-40 min while a brain-esophageal temperature difference greater than 3 °C was maintained over 6 h. There was no evidence of nasal or nasopharynx mucosal swelling, necrosis, or hemorrhage on MRI examination. CBF first decreased and then stabilized together with brain temperature before increasing to the baseline level during rewarming. CONCLUSIONS: SBC was accomplished by blowing cold air from a vortex tube into the nasal cavities. Due to its portability, the method can be used continuously in resuscitated patients in both in- and out-of-hospital situations without interruption.

4.
Am J Emerg Med ; 34(5): 887-94, 2016 May.
Article in English | MEDLINE | ID: mdl-26970864

ABSTRACT

Vortex tubes are simple mechanical devices to produce cold air from a stream of compressed air without any moving parts. The primary focus of the current study is to investigate the feasibility and efficiency of nasopharyngeal brain cooling method using a vortex tube. Experiments were conducted on 5 juvenile pigs. Nasopharygeal brain cooling was achieved by directing cooled air via a catheter in each nostril into the nasal cavities. A vortex tube was used to generate cold air using various sources of compressed air: (I) hospital medical air outlet (n = 1); (II) medical air cylinders (n = 3); and (III) scuba (diving) cylinders (n = 1). By using compressed air from a hospital medical air outlet at fixed inlet pressure of 50 PSI, maximum brain-rectal temperature gradient of -2°C was reached about 45-60 minutes by setting the flow rate of 25 L/min and temperature of -7°C at the cold air outlet. Similarly, by using medical air cylinders at fill-pressure of 2265 PSI and down regulate the inlet pressure to the vortex tube to 50 PSI, brain temperature could be reduced more rapidly by blowing -22°C ± 2°C air at a flow rate of 50 L/min; brain-body temperature gradient of -8°C was obtained about 30 minutes. Furthermore, we examined scuba cylinders as a portable source of compressed gas supply to the vortex tube. Likewise, by setting up the vortex tube to have an inlet pressure of 25 PSI and 50 L/min and -3°C at the cold air outlet, brain temperature decreased 4.5°C within 10-20 min.


Subject(s)
Brain , Compressed Air , Hypothermia, Induced/methods , Nasopharynx , Animals , Feasibility Studies , Hypothermia, Induced/instrumentation , Intubation/instrumentation , Intubation/methods , Swine
5.
Neurocrit Care ; 24(1): 140-9, 2016 Feb.
Article in English | MEDLINE | ID: mdl-26490776

ABSTRACT

BACKGROUND: Mild hypothermia is an effective neuroprotective strategy for a variety of acute brain injuries. Cooling the nasopharynx may offer the capability to cool the brain selectively due to anatomic proximity of the internal carotid artery to the cavernous sinus. This study investigated the feasibility and efficiency of nasopharyngeal brain cooling by continuously blowing room temperature or cold air at different flow rates into the nostrils of normal newborn piglets. METHODS: Experiments were conducted on thirty piglets (n = 30, weight = 2.7 ± 1.5 kg). Piglets were anesthetized with 1­2% isoflurane and were randomized to receive one of four different nasopharyngeal cooling treatments: I. Room temperature at a flow rate of 3­4 L min(−1) (n = 6); II. −1 ± 2 °C at a flow rate of 3­4 L min(−1) (n = 6); III. Room temperature at a flow rate of 14­15 L min(−1) (n = 6); IV. −8 ± 2 °C at a flow rate of 14­15 L min(−1) (n = 6). To control for the normal thermal regulatory response of piglets without nasopharyngeal cooling, a control group of piglets (n = 6) had their brain temperature monitored without nasopharyngeal cooling. The duration of treatment was 60 min, with additional 30 min of observation. RESULTS: In group I, median cooling rate was 1.7 ± 0.9 °C/h by setting the flow rate of room temperature air to 3­4 L min(−1). Results of comparing different temperatures and flow rates in the nasopharyngeal cooling approach reveal that the brain temperature could be reduced rapidly at a rate of 5.5 ± 1.1 °C/h by blowing −8 ± 2 °C air at a flow rate of 14­15 L min(−1). CONCLUSIONS: Nasopharyngeal cooling via cooled insufflated air can lower the brain temperature, with higher flows and lower temperatures of insufflated air being more effective.


Subject(s)
Body Temperature/physiology , Brain , Hypothermia, Induced/methods , Nasopharynx , Animals , Animals, Newborn , Cold Temperature , Feasibility Studies , Female , Male , Random Allocation , Swine
6.
Physiol Rep ; 3(7)2015 Jul.
Article in English | MEDLINE | ID: mdl-26149280

ABSTRACT

In fetal sheep, the electrocorticogram (ECOG) recorded directly from the cortex during repetitive heart rate (FHR) decelerations induced by umbilical cord occlusions (UCO) predictably correlates with worsening hypoxic-acidemia. In human fetal monitoring during labor, the equivalent electroencephalogram (EEG) can be recorded noninvasively from the scalp. We tested the hypothesis that combined fetal EEG - FHR monitoring allows for early detection of worsening hypoxic-acidemia similar to that shown for ECOG-FHR monitoring. Near-term fetal sheep (n = 9) were chronically instrumented with arterial and venous catheters, ECG, ECOG, and EEG electrodes and umbilical cord occluder, followed by 4 days of recovery. Repetitive UCOs of 1 min duration and increasing strength (with regard to the degree of reduction in umbilical blood flow) were induced each 2.5 min until pH dropped to <7.00. Repetitive UCOs led to marked acidosis (arterial pH 7.35 ± 0.01 to 7.00 ± 0.03). At pH of 7.22 ± 0.03 (range 7.32-7.07), and 45 ± 9 min (range 1 h 33 min-20 min) prior to attaining pH < 7.00, both ECOG and EEG amplitudes began to decrease ~fourfold during each FHR deceleration in a synchronized manner. Confirming our hypothesis, these findings support fetal EEG as a useful adjunct to FHR monitoring during human labor for early detection of incipient fetal acidemia.

7.
J Nucl Med ; 56(2): 299-304, 2015 Feb.
Article in English | MEDLINE | ID: mdl-25572090

ABSTRACT

UNLABELLED: Inflammation that occurs after acute myocardial infarction plays a pivotal role in healing by facilitating the creation of a supportive scar. (18)F-FDG, which is taken up avidly by macrophages, has been proposed as a marker of cell-based inflammation. However, its reliability as an accurate indicator of inflammation has not been established, particularly in the early postinfarction period when regional myocardial perfusion is often severely compromised. METHODS: Nine adult dogs underwent left anterior descending coronary occlusion with or without reperfusion. Animals were imaged between 7 and 21 d after infarction with PET/MR imaging after bolus injection of gadolinium-diethylenetriaminepentaacetic acid (DTPA), bolus injection of (18)F-FDG, bolus injection of (99)Tc-DTPA to simulate the distribution of gadolinium-DTPA (which represents its partition coefficient in well-perfused tissue), and injection of (111)In-labeled white blood cells 24 h earlier. After sacrifice, myocardial tissue concentrations of (18)F, (111)In, and (99)Tc were determined in a well counter. Linear regression analysis evaluated the relationships between the concentrations of (111)In and (18)F and the dependence of the ratio of (111)In/(18)F to the apparent distribution volume of (99m)Tc-DTPA. RESULTS: In 7 of 9 animals, (111)In increased as (18)F increased with the other 2 animals, showing weak negative slopes. With respect to the dependence of (111)In/(18)F with partition coefficient, 4 animals showed no dependence and 4 showed a weak positive slope, with 1 animal showing a negative slope. Further, in regions of extensive microvascular obstruction, (18)F significantly underestimated the extent of the presence of (111)In. CONCLUSION: In the early post-myocardial infarction period, (18)F-FDG PET imaging after a single bolus administration may underestimate the extent and degree of inflammation within regions of microvascular obstruction.


Subject(s)
Fluorodeoxyglucose F18 , Inflammation/diagnostic imaging , Myocardial Infarction/pathology , Animals , Coronary Circulation , Coronary Occlusion/pathology , Coronary Vessels/pathology , Dogs , Female , Gadolinium DTPA/chemistry , Image Processing, Computer-Assisted , Macrophages/diagnostic imaging , Magnetic Resonance Imaging , Microcirculation , Multimodal Imaging , Pentetic Acid/chemistry , Positron-Emission Tomography , Reproducibility of Results , Technetium/chemistry , Time Factors
8.
IEEE J Transl Eng Health Med ; 3: 1500108, 2015.
Article in English | MEDLINE | ID: mdl-27170888

ABSTRACT

We investigate thermal effects of pulmonary cooling which was induced by cold air through an endotracheal tube via a ventilator on newborn piglets. A mathematical model was initially employed to compare the thermal impact of two different gas mixtures, O2-medical air (1:2) and O2-Xe (1:2), across the respiratory tract and within the brain. Following mathematical simulations, we examined the theoretical predictions with O2-medical air condition on nine anesthetized piglets which were randomized to two treatment groups: 1) control group ([Formula: see text]) and 2) pulmonary cooling group ([Formula: see text]). Numerical and experimental results using O2-medical air mixture show that brain temperature fell from 38.5 °C and 38.3 °C ± 0.3 °C to 35.7 °C ± 0.9 °C and 36.5 °C ± 0.6 °C during 3 h cooling which corresponded to a mean cooling rate of 0.9 °C/h ± 0.2 °C/h and 0.6 °C/h ± 0.1 °C/h, respectively. According to the numerical results, decreasing the metabolic rate and increasing air velocity are helpful to maximize the cooling effect. We demonstrated that pulmonary cooling by cooling of inhalation gases immediately before they enter the trachea can slowly reduce brain and core body temperature of newborn piglets. Numerical simulations show no significant differences between two different inhaled conditions, i.e., O2-medical air (1:2) and O2-Xe (1:2) with respect to cooling rate.

9.
J R Soc Interface ; 10(81): 20121046, 2013 Apr 06.
Article in English | MEDLINE | ID: mdl-23365198

ABSTRACT

Magnetoreception in the animal kingdom has focused primarily on behavioural responses to the static geomagnetic field and the slow changes in its magnitude and direction as animals navigate/migrate. There has been relatively little attention given to the possibility that weak extremely low-frequency magnetic fields (wELFMF) may affect animal behaviour. Previously, we showed that changes in nociception under an ambient magnetic field-shielded environment may be a good alternative biological endpoint to orientation measurements for investigations into magnetoreception. Here we show that nociception in mice is altered by a 30 Hz field with a peak amplitude more than 1000 times weaker than the static component of the geomagnetic field. When mice are exposed to an ambient magnetic field-shielded environment 1 h a day for five consecutive days, a strong analgesic (i.e. antinociception) response is induced by day 5. Introduction of a static field with an average magnitude of 44 µT (spatial variability of ±3 µT) marginally affects this response, whereas introduction of a 30 Hz time-varying field as weak as 33 nT has a strong effect, reducing the analgesic effect by 60 per cent. Such sensitivity is surprisingly high. Any purported detection mechanisms being considered will need to explain effects at such wELFMF.


Subject(s)
Magnetic Fields , Nociception/physiology , Sensation/physiology , Sensory Thresholds/physiology , Animals , Male , Mice , Pain Measurement
10.
Bioelectromagnetics ; 32(7): 561-9, 2011 Oct.
Article in English | MEDLINE | ID: mdl-21381048

ABSTRACT

Previous experiments with mice have shown that a repeated 1 h daily exposure to an ambient magnetic field shielded environment induces analgesia (anti-nociception). This shielding reduces ambient static and extremely low frequency magnetic fields (ELF-MF) by approximately 100 times for frequencies below 120 Hz. To determine the threshold of ELF-MF amplitude that would attenuate or abolish this effect, 30 and 120 Hz magnetic fields were introduced into the shielded environment at peak amplitudes of 25, 50, 100 and 500 nT. At 30 Hz, peak amplitudes of 50, 100, and 500 nT attenuated this effect in proportion to the amplitude magnitude. At 120 Hz, significant attenuation was observed at all amplitudes. Exposures at 10, 60, 100, and 240 Hz with peak amplitudes of 500, 300, 500, and 300 nT, respectively, also attenuated the induced analgesia. No exposure abolished this effect except perhaps at 120 Hz, 500 nT. If the peak amplitude frequency product was kept constant at 6000 nT-Hz for frequencies of 12.5, 25, 50, and 100 Hz, the extent of attenuation was constant, indicating that the detection mechanism is dependent on the nT-Hz product. A plot of effect versus the induced current metric nT-Hz suggests a threshold of ELF-MF detection in mice at or below 1000 nT-Hz.


Subject(s)
Environmental Exposure/analysis , Magnetic Fields , Nociception/radiation effects , Analgesia , Analysis of Variance , Animals , Male , Mice , Pain Measurement
11.
Bioelectromagnetics ; 31(6): 445-53, 2010 Sep.
Article in English | MEDLINE | ID: mdl-20564168

ABSTRACT

For 8 weeks, adult CD-1 male mice were continuously exposed to complex time-varying pulsed magnetic fields (PMF) generated in the horizontal direction by a set of square Helmholtz coils. The PMF were <1000 Hz and delivered at a peak flux density of 1 mT. Sham-exposed mice were kept in a similar exposure system without a PMF. Positive control animals exposed to 1 Gy gamma radiation were also included in the study. Blood samples were collected before (time 0) and at 2, 4, 6, and 8 weeks. All mice were euthanized at the end of 8 weeks and their bone marrow was collected. From each blood and bone marrow sample, smears were prepared on microscope slides, fixed in absolute methanol, air-dried, and stained with acridine orange. All slides were coded and examined using a fluorescence microscope. The extent of genotoxicity and cytotoxicity was assessed from the incidence of micronuclei (MN) and percent polychromatic erythrocytes (PCE) in the blood and bone marrow, respectively. The data indicated that both indices in PMF-exposed mice were not significantly different from those observed in sham-exposed animals. In contrast, positive control mice exhibited significantly increased MN, and decreased percentages of PCE in both tissues. Thus, the overall data suggested that 8 weeks of continuous exposure to PMF did not induce significantly increased genotoxicity and cytotoxicity in experimental mice. Further investigations are underway using other genotoxicity assays (comet assay, gamma-H2AX foci, and chromosomal aberrations) to assess genotoxicity following PMF exposure.


Subject(s)
Blood Cells/metabolism , Blood Cells/radiation effects , Bone Marrow Cells/metabolism , Bone Marrow Cells/radiation effects , Electromagnetic Fields/adverse effects , Micronuclei, Chromosome-Defective , Animals , Blood Cells/cytology , Bone Marrow Cells/cytology , Erythrocytes/cytology , Erythrocytes/radiation effects , Male , Mice , Micronucleus Tests , Time Factors
12.
J R Soc Interface ; 6(30): 17-28, 2009 Jan 06.
Article in English | MEDLINE | ID: mdl-18583276

ABSTRACT

Previous experiments with mice have shown that repeated 1 hour daily exposure to an ambient magnetic field-shielded environment induces analgesia (antinociception). The exposures were carried out in the dark (less than 2.0x1016 photonss-1m-2) during the mid-light phase of the diurnal cycle. However, if the mice were exposed in the presence of visible light (2.0x1018 photonss-1m-2, 400-750 nm), then the analgesic effects of shielding were eliminated. Here, we show that this effect of light is intensity and wavelength dependent. Introduction of red light (peak at 635 nm) had little or no effect, presumably because mice do not have photoreceptors sensitive to red light above 600 nm in their eyes. By contrast, introduction of ultraviolet light (peak at 405 nm) abolished the effect, presumably because mice do have ultraviolet A receptors. Blue light exposures (peak at 465 nm) of different intensities demonstrate that the effect has an intensity threshold of approximately 12% of the blue light in the housing facility, corresponding to 5x1016 photonss-1m-2 (integral). This intensity is similar to that associated with photoreceptor-based magnetoreception in birds and in mice stimulates photopic/cone vision. Could the detection mechanism that senses ambient magnetic fields in mice be similar to that in bird navigation?


Subject(s)
Electromagnetic Fields , Light , Magnetics , Pain Measurement/radiation effects , Animals , Male , Mice , Ontario , Spectrophotometry , Ultraviolet Rays
13.
J Biomed Opt ; 13(5): 054052, 2008.
Article in English | MEDLINE | ID: mdl-19021432

ABSTRACT

Photoacoustic imaging (PAI) has the potential to acquire 3-D optical images at high speed. Attempts at 3-D photoacoustic imaging have used a dense 2-D array of ultrasound detectors or have densely scanned a single detector on a 2-D surface. The former approach is costly and complicated to realize, while the latter is inherently slow. We present a different approach based on a sparse 2-D array of detector elements and an iterative reconstruction algorithm. This approach has the potential for fast image acquisition, since no mechanical scanning is required, and for simple and compact construction due to the smaller number of detector elements. We obtained spatial sensitivity maps of the sparse array and used them to optimize the image reconstruction algorithm. We then validated the method on phantoms containing 3-D distributions of optically absorbing point sources. Reconstruction of the point sources from the time-domain signals resulted in images with good contrast and accurate localization (< or =1 mm error). Image acquisition time was 1 s. The results suggest that 3-D PAI with a sparse array of detector elements is a viable approach. Furthermore, the rapid acquisition speed indicates the possibility of high frame rate 3-D PAI.


Subject(s)
Algorithms , Image Interpretation, Computer-Assisted/instrumentation , Image Interpretation, Computer-Assisted/methods , Imaging, Three-Dimensional/instrumentation , Microscopy, Acoustic/instrumentation , Microscopy, Acoustic/methods , Equipment Design , Equipment Failure Analysis , Image Enhancement/instrumentation , Image Enhancement/methods , Phantoms, Imaging , Reproducibility of Results , Sensitivity and Specificity
14.
Bioelectromagnetics ; 27(1): 10-5, 2006 Jan.
Article in English | MEDLINE | ID: mdl-16283641

ABSTRACT

Orientation and nociception (pain sensitivity) are affected by exposure to geomagnetic or low frequency (<1,000 Hz) magnetic fields of approximately the earth's field strength, i.e., 50 microT. However, these effects are often dependent on the simultaneous presence of visible light. Recently, it was shown that nociception was affected in mice acutely exposed to an electromagnetic-shielded environment in the dark (<0.05 W/m(2)) during the mid-light phase of the diurnal cycle. Here, we report for the first time that if mice are exposed to magnetic shielding in the presence of visible light (0.6 W/m(2), 400-750 nm) that most of the effects of shielding are eliminated. This simple experimental protocol may be useful in investigating the role that light plays in the detection of ambient electromagnetic fields.


Subject(s)
Light , Magnetics , Pain Measurement , Animals , Darkness , Electromagnetic Fields , Male , Mice
15.
Bioelectromagnetics ; 26(5): 367-76, 2005 Jul.
Article in English | MEDLINE | ID: mdl-15887255

ABSTRACT

Continuing evidence suggests that extremely low frequency magnetic fields (ELF MFs) can affect animal and human behavior. We have previously demonstrated that after a 15 min exposure to a pulsed ELF MF, with most power at frequencies between 0 and 500 Hz, human brain electrical activity is affected as measured by electroencephalography (EEG), specifically within the alpha frequency (8-13 Hz). Here, we report that a pulsed ELF MF affects the human EEG during the exposure period. Twenty subjects (10 males; 10 females) received both a magnetic field and a sham session of 15 min in a counterbalanced design. Analysis of variance (ANOVA) revealed that alpha activity was significantly lower over the occipital electrodes (O1, Oz, O2) [F(1,16) = 5.376, P < .01, eta2 = 0.418] after the first 5 min of magnetic field exposure and was found to be related to the order of exposure (MF-sham vs. sham-MF). This decrease in alpha activity was no longer significant in the 1st min post-exposure, compared to sham (P > .05). This study is among the first to assess EEG frequency changes during a weak (+/-200 microTpk), pulsed ELF MF exposure.


Subject(s)
Brain/physiology , Brain/radiation effects , Electroencephalography/radiation effects , Electromagnetic Fields , Environmental Exposure , Rest/physiology , Adaptation, Physiological/physiology , Adaptation, Physiological/radiation effects , Adult , Dose-Response Relationship, Radiation , Electroencephalography/methods , Female , Humans , Male , Radiation Dosage
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