Pharmacokinetics of Ketamine and Xylazine in Young and Old Sprague–Dawley Rats

To compare the pharmacokinetics of coadministered intraperitoneal ketamine and xylazine in young (8 to 10 wk; n = 6) and old rats (2 to 2.4 y; n = 6), blood samples obtained at 15 and 30 min and 1, 2, and 4 h after drug administration were analyzed by HPLC–tandem mass spectrometry. In both groups, the withdrawal reflex was absent during anesthesia and was present at 1.1 (± 0.2) and 2.6 (± 0.7) h after drug administration in young and old rats, respectively, with the first voluntary movement at 1.5 ± 0.2 and 4.9 ± 1.0 h. Drug availability of ketamine and xylazine was 6.0 and 6.7 times greater, respectively, in old than young rats. The rate constant of elimination of both drugs was greatly decreased and the elimination half-life was significantly greater in old compared with young rats. In conclusion, age and associated factors affect the availability of ketamine and xylazine when coadministered to attain clinical anesthesia, changing the pharmacokinetics of these drugs and prolonging anesthesia duration and recovery times with aging. Compared with their young counterparts, aged rats required much higher doses to attain a similar level of anesthesia. Finally, the long half-life of both ketamine and xylazine, when coadministered to old rats, may be a factor in research protocols because residual plasma concentrations could still be present for as long as 3 and 5 d, respectively, after administration.Abbreviations: C_last, last measurable plasma concentration; K_el, terminal elimination rate constantKetamine, an N-methyl d-aspartate antagonist with anesthetic properties, and xylazine, an α2-adrenoreceptor agonist with sedative and antinociceptive effects, are often used in combination to anesthetize rodents. They are administrated intramuscularly, intraperitoneally, or intravenously to provide relief of pain and distress.²⁷ Ketamine combinations are considered to be a first choice in rodents when injectable anesthetics are used.^6,20 Ketamine and xylazine are metabolized mainly by liver cytochromes P450 enzymes and excreted by the kidney.¹¹ Both drugs are rapidly absorbed and well distributed to the CNS.²⁴ However little is known about their pharmacokinetics in aged animals. Commercial ketamine preparations are composed of 2 enantiomers (the S-enantiomer is more active and produces fewer side effects),¹⁹ and cytochrome metabolism is different across different animal species;¹⁸ therefore findings in rats may not extrapolate to other species.The main objective of the current study was to compare the pharmacokinetics of ketamine and xylazine in young and old rats when coadministered at anesthetic doses to determine a safer, more appropriate combination of injectable drugs for anesthesia of aged rats.     

Heart Rates of Male and Female Sprague�CDawley and Spontaneously Hypertensive Rats Housed Singly or in Groups

This study was conducted to confirm our previous reports that group housing lowered basal heart rate and various evoked heart-rate responses in Sprague–Dawley male and female rats and to extend these observations to spontaneously hypertensive rats. Heart rate data were collected by using radiotelemetry. Initially, group- and single-housed rats were evaluated in the same animal room at the same time. Under these conditions, group-housing did not decrease heart rate in undisturbed male and female rats of either strain compared with single-housed rats. Separate studies then were conducted to examine single-housed rats living in the room with only single-housed rats. When group-housed rats were compared with these single-housed rats, undisturbed heart rates were reduced significantly, confirming our previous reports for Sprague–Dawley rats. However, evoked heart rate responses to acute procedures were not reduced universally in group-housed rats compared with either condition of single housing. Responses to some procedures were reduced, but others were not affected or were significantly enhanced by group housing compared with one or both of the single-housing conditions. This difference may have been due, in part, to different sensory stimuli being evoked by the various procedures. In addition, the variables of sex and strain interacted with housing condition. Additional studies are needed to resolve the mechanisms by which evoked cardiovascular responses are affected by housing, sex, and strain.Group housing of rodents is recommended on grounds that it reduces stress that accompanies isolated housing and therefore improves animal wellbeing. Experimental evidence supporting this recommendation depends on methods that can monitor stress levels or wellbeing effectively. Several techniques to detect stress in rodents are currently in use. Radiotelemetry methods have allowed for minute-to-minute determination of cardiovascular and body temperature responses.^{2,4,17,20,22,23,25,27,33,34,38,39,46,47,50} Chronic blood sampling through indwelling catheters makes it possible to monitor the blood levels of stress hormones (for example, glucocorticoids, prolactin) in conscious animals,^{18,28,31,35,36,45} whereas serial collection of feces has allowed for the noninvasive monitoring of fecal corticosterone metabolites in rats.¹⁵To reduce stress and improve wellbeing, several methods that alter the animal''s environment have been studied. These include the addition of enrichment devices to the animal''s home cage,⁴¹ increased cage size,⁴³ and reduced ambient illumination³. Extending the dark phase of the photocycle has been shown to decrease blood pressure and heart rate in rats^3,51 and may prove to be yet another method to reduce stress. Finally and directly related to the current studies, social enrichment by group or colony housing has been reported to reduce cardiovascular parameters in rats,^5,14,42,44 suggesting a reduced level of stress, but this method actually can contribute to stress if the number of rats housed together produces crowding or if aggressive interaction between animals occurs.⁵The initial objectives of the current study were to confirm our previous reports of the effects of group housing on basal heart rate and evoked heart rate responses in Sprague–Dawley rats and to determine whether the effects of housing generally extend to male and female rats of other strains. We chose to evaluate the spontaneously hypertensive rat (SHR) strain because it is very susceptible to stress.^26,29,30,32 Both sexes were included for completeness of the comparisons. As the study progressed, results indicated that group- and single-housed rats living in the same room at the same time may interact with each other. Therefore, a third objective was added to determine whether our previous results could be replicated when group- and single-housed rats are in close proximity to each other.The hypotheses tested in the current studies were: that group-housing reduces heart rate in undisturbed rats; that compared with single housing, group housing reduces heart-rate responses induced by acute procedures; and that housing effects are influenced by sex and strain.     

The Influence of Red Light Exposure at Night on Circadian Metabolism and Physiology in Sprague–Dawley Rats

Early studies on rodents showed that short-term exposure to high-intensity light (> 70 lx) above 600 nm (red-appearing) influences circadian neuroendocrine and metabolic physiology. Here we addressed the hypothesis that long-term, low-intensity red light exposure at night (rLEN) from a ‘safelight’ emitting no light below approximately 620 nm disrupts the nocturnal circadian melatonin signal as well as circadian rhythms in circulating metabolites, related regulatory hormones, and physiologic parameters. Male Sprague–Dawley rats (n = 12 per group) were maintained on control 12:12-h light:dark (300 lx; lights on, 0600) or experimental 12:12 rLEN (8.1 lx) lighting regimens. After 1 wk, rats underwent 6 low-volume blood draws via cardiocentesis (0400, 0800, 1200, 1600, 2000, and 2400) over a 4-wk period to assess arterial plasma melatonin, total fatty acid, glucose, lactic acid, pO₂, pCO₂, insulin, leptin and corticosterone concentrations. Results revealed plasma melatonin levels (mean ± 1 SD) were high in the dark phase (197.5 ± 4.6 pg/mL) and low in the light phase (2.6 ± 1.2 pg/mL) of control conditions and significantly lower than controls under experimental conditions throughout the 24-h period (P < 0.001). Prominent circadian rhythms of plasma levels of total fatty acid, glucose, lactic acid, pO₂, pCO₂, insulin, leptin, and corticosterone were significantly (P < 0.05) disrupted under experimental conditions as compared with the corresponding entrained rhythms under control conditions. Therefore, chronic use of low-intensity rLEN from a common safelight disrupts the circadian organization of neuroendocrine, metabolic, and physiologic parameters indicative of animal health and wellbeing.Abbreviation: rLEN, red light exposure at night; SCN, suprachiasmatic nuclei; TFA, total fatty acidLight is a powerful biologic force that entrains circadian rhythms of behavior, physiology and metabolism for all mammals.^{1-3,4,7-12,26,27,29,56,63} Alterations in intensity, duration, and spectral transmittance (that is, wavelength; perceived as color) of light at an inappropriate time of the day can induce the disruption of many circadian rhythms, including those of locomotor activity,^2,3,21,44,54 the sleep–wake cycle,^2,3,21 dietary and water intake,^2,3,21,38 metabolism,^{5,6,13-18,38,39,44,60} and neurologic functions,⁴³ among others. Circadian disruption is defined here as a significant change in the phasing, periodicity, amplitude, or duration of a circadian rhythm from its usual entrained pattern under 12:12-h light:dark conditions. Our early work provided the first in vivo experimental evidence demonstrating that the increased risk of breast cancer in humans, as occurs in the night-shift worker population, may be mediated by light exposure at night.^19,31,57 Our previous studies^4,5,13-18,64 also showed that adherence to appropriate lighting and lighting protocols, as outlined in The Guide for the Care and Use of Laboratory Animals,³⁷ is not only beneficial for but essential to the health and wellbeing of laboratory animals and experimental outcomes. For example, we found that a small light leak of as little as 0.2 lx (0.08 μW/cm²) intensity during an otherwise normal dark phase (12 h) in our animal rooms elicited a disruption in circadian rhythms of plasma measures of endocrine physiology and metabolism in rats.^13-18,64 In a process termed phototransduction, photic information from the eyes is transmitted via the retinohypothalamic tract, which projects to the suprachiasmatic nuclei (SCN), or master biologic clock; in turn, signals from the SCN to the pineal gland via a polysynaptic pathway regulate the nocturnal production of the hormone melatonin (N-acetyl-5-methoxytryptamine).^36,48,53,54 More recent studies^17,18,64 revealed that the spectral transmittance of light (blue-, amber-, or red-appearing) through laboratory rodent cages dramatically influences the temporal coordination of circadian patterns of plasma melatonin, total fatty acid (TFA), glucose, lactic acid, corticosterone, pO₂ and pCO₂ levels in both pigmented and nonpigmented rats.^17,18,64For many years, it has been common practice to make use of red ‘safe lamps’ (wavelengths above 600 nm) during dark-phase laboratory animal exposure or to cover animal room rodent racks, lights, and observation windows with red-tinted film primarily for nighttime observation.^{24,44,45,62,65} It was assumed light with wavelengths above 600 nm (red) had little or no effect on neurodendocrine or circadian systems, given that several nonpigmented species (felines, canines, ungulates, and most species of marine mammals) cannot visually perceive red light via the primary optic tract,^43,47 despite a few early studies on nonpigmented rodents showing otherwise.^43-45,60 Both polychromatic and analytic action spectra studies in humans subsequently showed that these responses to red-appearing light were weak.^8,28,29 At similar irradiances, the acute melatonin-suppressive effects of full-spectrum light were not observed with red light in most mammalian species.^7,38,53 This finding led to the use of red-tinted observation windows and red safety lights for nighttime laboratory animal observation.Recent studies in both rats and humans have shown, however, that high-intensity red light^8,30,51,59 over a short duration (that is, minutes) elicits marked suppression of the nocturnal melatonin signal. Long-wavelength light in the spectral region above 550 nm (perceived as yellow to red) of sufficiently high intensity and duration can acutely suppress melatonin and cause phase shifts or entrain circadian rhythms primarily by means of the nonvisual neural pathway of the retinohypothalamic tract.^{30,34,45-47,50} Input to the retinohypothalamic tract differs from the classic visual rod-and-cone system of the primary optic tract, relying rather on a small subset of retinal ganglion cells called the intrinsically photosensitive retinal ganglion cells.^{3,26,32,33,43,52,60} The neurophysiology of this newly detailed sensory pathway has important implications for consideration in the measurement, production, and application of light in all settings, including those of both human and laboratory animal environments.⁴³ Many investigators and animal care personnel, however, still assume that the use of light above 610 nm (orange- to red-appearing) for observation purposes, particularly at nighttime, results in little or no circadian disruptive effect on normal circadian physiology and behavior.^45,65 Arguably, sufficient scientific justification for the chronic use of red-tinted observation windows or red safelights, for examining potential neuroendocrine, neurobehavioral, metabolic, and physiologic parameters in laboratory animals is unavailable.In this study we examined the hypothesis that chronic, low-intensity red light exposure throughout an otherwise normal dark phase (that is, red light exposure at night, rLEN) disrupts circadian melatonin production and the temporal coordination of normal metabolic and physiologic activities in the nonpigmented rat species commonly used for the preclinical study of human physiology or pathophysiology. Our approach was to expose experimental rats, for several weeks and under highly controlled conditions, to a low-intensity safelight (1A Red Safelight, Eastman Kodak, Rochester, NY) during the daily 12-h dark phase and compare their responses with those of control animals maintained under total dark-phase conditions. Use of the safelight eliminated potentially confounding factors in spectral transmittance variability of the many types of red-tinted observation windows and coverings in common use today by ensuring that experimental animals were exposed only to red light in the visible spectrum of wavelengths above 620 nm. Light intensity, duration, and wavelength during light phase were the same for all animals.     

The Effects of Minocycline or Riluzole Treatment on Spinal Root Avulsion–Induced Pain in Adult Rats

Spinal root avulsion produces tactile and thermal hypersensitivity, neurodegeneration, and microglial and astrocyte activation in both the deafferented and the adjacent intact spinal cord segments. Following avulsion of the fifth lumbar spinal root, immediate and prolonged treatment with riluzole or minocycline for 2 weeks altered the development of behavioral hypersensitivity. Riluzole delayed the onset of thermal and tactile hypersensitivity and partially reversed established pain behavior. Minocycline effectively prevented and reversed both types of behavioral change. Histologic analysis revealed that both drugs reduced microglial staining in the spinal cord, with minocycline being more effective than riluzole. Astrocyte activation was ameliorated to a lesser extent. Surprisingly, neither drug provided a neuroprotective effect on avulsed motoneurons.PerspectiveImmediate treatment of spinal root avulsion injuries with minocycline or riluzole prevents the onset of evoked pain hypersensitivity by reducing microglial cell activation. When treatment is delayed, minocycline, but not riluzole, reverses pre-established hypersensitivity. Thus, these drugs may provide a new translational treatment option for chronic avulsion injury pain.     

The Impact of Different Lung Ultrasound Protocols in the Assessment of Lung Lesions in COVID-19 Patients: Is There an Ideal Lung Ultrasound Protocol?

BackgroundIn the past months, several lung ultrasonography (LUS) protocols have been proposed, mainly on previously validated schemes independent of coronavirus disease 2019 (COVID-19).ObjectivesThe main purpose of this study was to determine the impact and accuracy of different LUS protocols proposed in COVID-19.MethodsPatients were evaluated with a standard sequence of LUS scans in 72 intercostal spaces along 14 anatomic lines in the chest. A scoring system of LUS findings was reported and then analyzed separately according to each proposed LUS protocol zones. This score was then correlated to a validated Pulmonary Inflammation Index (PII) on chest Computed Tomography (CT).ResultsThirty-two patients were enrolled. The most frequent pattern was ground-glass opacities in the chest X-ray (53.1%), chest CT (59.1%) and subpleural or lobar consolidations (40.8%) in the posteroinferior areas (p < 0.001) on LUS. The Interclass Correlation Coefficient (ICC) was significantly correlated with almost every protocol analyzed except the 8-zone (p = 0.119) and the 10-zone protocol that only included one posterior point (p = 0.052). The highest ICC was obtained with a 12-zone protocol (ICC 0.500; p = 0.027) and decreased as more points were included.ConclusionsIn conclusion, our study results suggest that performing an ultrasound protocol with 12-zone scanning, including the superior and inferior areas of the anterior, lateral and posterior regions of the chest was consistent with higher ICC and higher degree of concordance with CT. We emphasize the need of a more standardization technique to further implement and develop this imaging modality in COVID-19.     

The “Survived Lung:” An Ultrasound Sign of “Bubbly Consolidation” Pulmonary Infarction

Since the presence of “bubbly consolidation” (central lucencies) on a multi-slice computed tomography pulmonary angiography (MCTPA) is one of the highly specific imaging appearances of infarct secondary to pulmonary embolism, we investigated the ultrasound characteristics of these infarctions. In this study, 118 patients with MCTPA diagnosis of acute pulmonary embolism were enrolled. Pulmonary infarctions were detected in 21 patients (17.7%), of which 10 (47.6%) showed the typical appearance of bubbly consolidation on MCTPA. Lung ultrasound (LUS) was performed to evaluate the characteristics of the infarcts highlighted by MCTPA. The bubbly consolidations showed a very peculiar echographic aspect represented by a triangular hypoechoic consolidation with sharp margins, the absence of air bronchograms and a mostly central roundish hyperechoic area. Air lucencies within a pulmonary infarct is hypothesized to represent the coexistence of aerated non-infarcted lung with the infarcted lung in the same lobule. The ultrasound appearance confirms this hypothesis, so we named the roundish hyperechoic area the “survived lung.” This picture was found in all patients with a diagnosis of bubbly consolidation on MCTPA (100%). Χ² between MCTPA and LUS regarding the bubbly consolidation diagnosis is 17.18 (df = 1; p value = 0.00003). Bubbly consolidations show a very typical appearance on LUS. Their detection suggests further investigations (MCTPA or point-of-care multi-organ ultrasonography).     

Extensive Analysis of Elastase-Induced Pulmonary Emphysema in Rats: ALP in the Lung,a New Biomarker for Disease Progression?

It is accepted that pulmonary exposure of rodents to porcine pancreatic elastase (ELT) induces lesions that morphologically resemble human emphysema. Nonetheless, extensive analysis of this model has rarely been conducted. The present study was designed to extensively examine the effects of ELT on lung inflammation, cell damage, emphysematous change, and cholinergic reactivity in rats. Intratracheal administration of two doses of ELT induced 1) a proinflammatory response in the lung that was characterized by significant infiltration of macrophages and an increased level of interleukin-1β in lung homogenates, 2) lung cell damage as indicated by higher levels of total protein, lactate dehydrogenase, and alkaline phosphatase (ALP) in lung homogenates, 3) emphysema-related morphological changes including airspace enlargement and progressive destruction of alveolar wall structures, and 4) airway responsiveness to methacholine including an augmented Rn value. In addition, ELT at a high dose was more effective than that at a low dose. This is the novel study to extensively analyze ELT-induced lung emphysema, and the analysis might be applied to future investigations that evaluate new therapeutic agents or risk factors for pulmonary emphysema. In particular, ALP in lung homogenates might be a new biomarker for the disease progression/exacerbation.     

Ultrasound Evaluation of Anti-Vascular Endothelial Growth Factor–Induced Changes in Vascular Response Following Tendon Injury

While vascular ingrowth is necessary for tendon healing, hypervascularization following tendon injury is not always believed to be beneficial, and there is now evidence showing beneficial results of anti-angiogenic treatments in the context of tendon healing. However, the dose-dependency of anti-angiogenic–altered vascular response, as well as methods for evaluating these changes in vivo, has not been fully investigated. Therefore, the objective of this study was to evaluate if in vivo ultrasound imaging can detect dose-dependent, anti-angiogenic treatment–induced changes in vascularity in rat Achilles tendon after injury. Color Doppler ultrasound revealed an increase in vascularity in a low-dosage group, while photoacoustic imaging demonstrated a decrease in vascularity in mid- and high-dosage groups. Histologic staining supported the decrease in vascularity observed in the mid-dosage group. This study demonstrates dose-dependent vascular alterations from the delivery of an anti-angiogenic factor after tendon injury that can be detected through ultrasound imaging methods.     

Effects of Handling and Vehicle Injections on Adrenocorticotropic and Corticosterone Concentrations in Sprague–Dawley Compared with Lewis Rats

The hypothalamic–pituitary–adrenal (HPA) axis is a key factor in the trajectory of the addiction-like cycle (a pattern of behavior characterized by escalating drug use, withdrawal, and relapse) in preclinical and clinical studies. Concentrations of HPA hormones change in laboratory animals in response to standard experimental procedures, including handling and vehicle injections. We compared HPA activity in adult male Lewis (inbred) and Sprague–Dawley (outbred) rats, 2 common strains in rodent models of addiction, after different schedules of handling and saline injections, to explore the extent to which HPA responses differ by strain and whether interindividual differences underlie addiction vulnerability. The 4 treatment conditions were no, short, or long handling and saline injections. In handled groups, rats were handled for 1 to 2 min for 3 times daily and were euthanized after 7 d (short handling) or 14 d (long handling). The injection schedule in the saline injection group mimicked that in a model of binge-like cocaine exposure. Across all treatment groups, concentrations of adrenocorticotropic hormone were higher in Sprague–Dawley than in Lewis rats. In Sprague–Dawley rats, corticosterone concentrations decreased after continued handling but remained constant in Lewis rats. Interindividual variability in hormone levels was greater in Sprague–Dawley than Lewis rats, although corticosterone variability decreased after continued handling. Prolactin did not differ between groups of either Sprague–Dawley and Lewis rats before or after handling. This study underscores the importance of prolonged handling before experimenter-provided drug-administration paradigms and of strain-associated differences that may affect study outcomes.Abbreviation: ACTH, adrenocorticotropic hormone; HPA, hypothalamic–pituitary–adrenalStudies in medical and life science often require repeated handling or injection of rodent subjects over the course of the experiment. Of primary concern is the ability to minimize stress associated with these procedures, which are necessary and unavoidable aspects of most behavioral, pharmacologic, and endocrine studies. A growing body of research suggests that experimental conditions, such as the presence and type of handling^3,7,30 and providing saline injections,^11,33 affect basal physiologic measures and, potentially, performance on behavioral assays.Inconsistencies and high variability in behavioral data have been attributed, in part, to differences in the laboratory environment, including animal housing and husbandry. In addition, several environmental factors have been shown to influence experimental outcomes. These include cage changes,^1,12 placement on cage racks,¹⁹ and environmental noise,^20,27,36 both in studies using mice^8,37 and rats.^13,19 These environmental differences may act as physical stressors, which are known to alter basal neuroendocrine stress responses and contribute to psychologic stress.¹¹ Although the specific process of handling or injection has been shown to affect endocrine stress responses in mice,¹¹ less is known about how these responses manifest in commonly used rat strains.Several groups have investigated the effects of various types of stress on rat hormone concentrations as well as the different hormonal response patterns of various rat strains. For example, corticosterone concentrations increased in response to amphetamine more dramatically in Sprague–Dawley rats than in Lewis rats.²¹ A similar pattern occurred after the rats experienced restraint stress.²⁰ Another study found that the initial rise in corticosterone levels due to restraint stress is attenuated in both Sprague–Dawley and Lewis rats after prolonged exposure to the stressor.¹⁰ In addition, a study comparing Lewis and Fischer rats found that during an extended-access self-administration protocol, neither ACTH nor corticosterone was elevated at 24 h after the rats’ final cocaine self-administration session in Lewis rats but remained increased in Fischer rats.²⁹The present study expands on these data by examining how standard laboratory techniques affect neuroendocrine stress responses. The techniques in this study were designed to mimic standard animal handling and injection protocols frequently used in neurobiologic endocrine studies. It is important to quantify the effect of these practices to understand how laboratory techniques contribute to changes in stress hormone concentrations and thereby influence study outcomes.Routine laboratory procedures such as handling and injections present stimuli that can be associated with mild to moderate physical or psychologic stress.¹⁶ The hypothalamic–pituitary–adrenal (HPA) axis regulates physiologic processes that enable adaptive responses to external stressors, including distress caused by handling or injections, and helps to maintain homeostasis. The intensity and duration of a stressful stimulus influences the magnitude of physiologic stress response produced by the subject,³⁵ and repeated exposure to the same stressor results in a reduction in response over time, that is, desensitization or habituation.^17,35 Minimizing disruptions to basal HPA activity is particularly important in pharmacologic and endocrine studies,³¹ because HPA responses prior to, during, and after exposure to drugs of abuse contribute importantly to the trajectory of drug dependence and addiction.^23,25,34The purpose of the current study was to compare changes in HPA response between 2 commonly used rat strains by using different handling and injection protocols, 2 typical laboratory procedures that can elicit stress. We compared these responses in outbred Sprague–Dawley rats with those from the inbred Lewis strain. Lewis rats have an HPA axis that is relatively hyporesponsive to stress, and this strain responds strongly to multiple drugs in several behavioral tests.^24,29We also measured prolactin, which, although not part of the HPA axis, is under hypothalamic control. An increased prolactin level has been associated with acute stress.² Therefore, handling may affect prolactin concentrations. In addition, measuring the prolactin concentration allows us to identify the extent to which handling influences nonHPA activity. Furthermore, prolactin affects the activity of tuberoinfundibular dopamine neurons²⁶ and can be used in translational research as an indirect biomarker for dopamine concentration.⁶ Given the established role of dopaminergic systems in several neurobiologic diseases and disorders, examining the role of prolactin response to handling stress may offer novel insight into the dysregulated circuits underlying these diseases.     

Renal Damages in Deoxycorticosterone Acetate–Salt Hypertensive Rats: Assessment with Diffusion Tensor Imaging and T2-mapping

Molecular Imaging and Biology - This study aimed to investigate the feasibility of diffusion tensor imaging (DTI) and T2-mapping to assess temporal renal damage in deoxycorticosterone...     

Value of Contrast-Enhanced Ultrasound Parameters in the Evaluation of Adnexal Masses with Ovarian–Adnexal Reporting and Data System Ultrasound

ObjectiveThe aim of this study was to determine whether incorporating qualitative parameters of contrast-enhanced ultrasound (CEUS) can increase the accuracy of adnexal lesion assessments with Ovarian–Adnexal Reporting and Data System (O-RADS) ultrasound category 4 or 5.MethodsRetrospective analysis of patients with adnexal masses who underwent conventional ultrasound (US) and contrast-enhanced ultrasound (CEUS) examinations between January and August of 2020. The study investigators reviewed and analyzed the morphological features of each mass before categorizing the US images independently according to the O-RADS system published by the American College of Radiology. In the CEUS analysis, the initial time and intensity of enhancement involving the wall and/or septation of the mass were compared with the uterine myometrium. Internal components of each mass were observed for signs of enhancement. The sensitivity, specificity, and Youden's index were calculated as the contrast variables and O-RADS.ResultsReceiver operating characteristic curve analysis revealed that the best cutoff value was higher than O-RADS 4. When information on the extent of enhancement was applied to selectively upgrade O-RADS category 4 and selectively downgrade O-RADS category 5, the overall sensitivity increased to 90.2%, while the level of specificity (91.3%) remained the same.ConclusionIncorporating additional information from CEUS with respect to the extent of enhancement helped to improve the sensitivity of O-RADS category 4 and 5 masses without loss of specificity.     

Influence of Nanobubble Concentration on Blood–Brain Barrier Opening Using Focused Ultrasound Under Real-Time Acoustic Feedback Control

Real-time acoustic feedback control based on harmonic emissions of stimulated microbubbles may serve as a way to achieve reliable blood–brain barrier (BBB) opening with focused ultrasound in the brain. Previously, we demonstrated BBB opening was possible using sub-micron bubbles (aka nanobubbles) and produced comparable results to commercially available microbubbles (Optison, Definity, etc.). The harmonic emissions and acoustic control were observed to be more consistent using nanobubbles, which warrants further study of BBB opening using these agents. This study examined the stimulated acoustic emissions of nanobubbles at different concentrations both in vitro and in vivo and evaluated BBB opening under real-time acoustic feedback control across concentrations. Original nanobubbles (10¹¹ bubbles/mL) have long in vitro persistence (7.3 ± 3.3 min) and circulation time in rats (approximately 10 min) under exposures in this study, and both degraded with dilutions. With all three tested dilutions (1:1, 1:10 and 1:100), successful BBB opening was reliably achieved under real-time feedback control.     

Involvement of ASIC3 and Substance P in Therapeutic Ultrasound–Mediated Analgesia in Mouse Models of Fibromyalgia

Therapeutic ultrasound (tUS) is widely used in chronic muscle pain control. However, its analgesic molecular mechanism is still not known. Our objective is to reveal the mechanism of the tUS-induced analgesia in mouse models of fibromyalgia. We applied tUS in mice that have developed chronic hyperalgesia induced by intramuscular acidification and determined the tUS frequency at 3 MHz, dosage at 1 W/cm² (measured output as 6.3 mW/cm²) and 100% duty cycle for 3 minutes having the best analgesic effect. Pharmacological and genetic approaches were used to probe the molecular determinants involved in tUS-mediated analgesia. A second mouse model of fibromyalgia induced by intermittent cold stress was further used to validate the mechanism underlying the tUS-mediated analgesia. The tUS-mediated analgesia was abolished by a pretreatment of NK1 receptor antagonist—RP-67580 or knockout of substance P (Tac1^-/-). Besides, the tUS-mediated analgesia was abolished by ASIC3-selective antagonist APETx2 but not TRPV1-selective antagonist capsazepine, suggesting a role for ASIC3. Moreover, the tUS-mediated analgesia was attenuated by ASIC3-selective nonsteroid anti-inflammation drugs (NSAIDs)—aspirin and diclofenac but not by ASIC1a-selective ibuprofen. We next validated the antinociceptive role of substance P signaling in the model induced by intermittent cold stress, in which tUS-mediated analgesia was abolished in mice lacking substance P, NK1R, Asic1a, Asic2b, or Asic3 gene. tUS treatment could activate ASIC3-containing channels in muscle afferents to release substance P intramuscularly and exert an analgesic effect in mouse models of fibromyalgia. NSAIDs should be cautiously used or avoided in the tUS treatment.PerspectiveTherapeutic ultrasound showed analgesic effects against chronic mechanical hyperalgesia in the mouse model of fibromyalgia through the signaling pathways involving substance P and ASIC3-containing ion channels in muscle afferents. NSAIDs should be cautiously used during tUS treatment.