Air Puff Research Articles

Comparison of Intraocular Pressure Measurement by Goldmann Applanation Tonometer, Air Puff Tonometer and Tonopen in Vitrectomized Eyes

Objective: To compare Goldmann applanation tonometer, air puff tonometer, and tonopen measured IOP Readings in vitrectomized eyes filled with temponading oils and gasses. Study Design: Comparative cross-sectional study. Place and Duration of Study: Armed Forces Institute of Ophthalmology (AFIO), Rawalpindi Pakistan, from Aug 2021 to Feb2022. Methodology: A total of 50 eyes were included in our study. Intraocular pressure was measured by an experienced ophthalmologist between 10am to 4pm on the 7th postoperative day by three devices, Goldmann applanation tonometer (GAT), air puff tonometer, and tonopen. Pearson’s correlation and paired samples t-test was applied to determine correlation and any significant difference between the mean of intraocular pressure measured by three different devices. Results: Out of the 50 people included in study 31(62%) were males and 19(38%) were females. The mean age of study participants was 50.10±11.61 years. Mean intraocular (IOP) pressure measured by the GAT applanation tonometer was 14.59±1.13 mmHg. Mean IOP as calculated by the airpuff tonometer was 15.93±1.88 mmHg, whereas mean IOP as calculated by tonopen was 15.85±1.86 mmHg. All three instrument values showed significant difference as p-value < 0.001. Conclusions: The air puff tonometer overestimates IOP as compared to GAT. Tonopen and air puff tonometer produce IOP measurements that are similar and consistent to each other but not to GAT

Overexpression of the autism candidate gene Cyfip1 pathologically enhances olivo-cerebellar signaling in mice.

Cyfip1, the gene encoding cytoplasmic FMR1 interacting protein 1, has been of interest as an autism candidate gene for years. A potential role in autism spectrum disorder (ASD) is suggested by its location on human chromosome 15q11-13, an instable region that gives rise to a variety of copy number variations associated with syndromic autism. In addition, the CYFIP1 protein acts as a binding partner to Fragile X Messenger Ribonucleoprotein (FMRP) in the regulation of translation initiation. Mutation of FMR1, the gene encoding FMRP, causes Fragile X syndrome, another form of syndromic autism. Here, in mice overexpressing CYFIP1, we study response properties of cerebellar Purkinje cells to activity of the climbing fiber input that originates from the inferior olive and provides an instructive signal in sensorimotor input analysis and plasticity. We find that CYFIP1 overexpression results in enhanced localization of the synaptic organizer neurexin 1 (NRXN1) at climbing fiber synaptic input sites on Purkinje cell primary dendrites and concomitant enhanced climbing fiber synaptic transmission (CF-EPSCs) measured using whole-cell patch-clamp recordings from Purkinje cells in vitro. Moreover, using two-photon measurements of GCaMP6f-encoded climbing fiber signals in Purkinje cells of intact mice, we observe enhanced responses to air puff stimuli applied to the whisker field. These findings resemble our previous phenotypic observations in a mouse model for the human 15q11-13 duplication, which does not extend to the Cyfip1 locus. Thus, our study demonstrates that CYFIP1 overexpression shares a limited set of olivo-cerebellar phenotypes as those resulting from an increased number of copies of non-overlapping genes located on chromosome 15q11-13.

Performance Testing of a Homemade Aerosol Generator for Pulmonary Administration of Dry Powder Formulations to Mice.

A challenge in the development of dry powder formulations for inhalation is the poor reproducibility of their administration to small laboratory animals. The currently used devices for the pulmonary administration of dry powder formulations to small rodents often function sub-optimally as they use the same puff of air for both powder dispersion and aerosol delivery. As a result, either the air volume and flow rate are too low for complete powder deagglomeration or they are too high for effective aerosol delivery to the lungs of the animal. Therefore, novel and better devices are desired. We here present an aerosol generator designed to administer a pre-generated aerosol to the lungs of mice. By mapping the complex relationship between the airflow rate, delivery time and emitted dose, we were able to control the amount of powder being delivered from the aerosol generator. The emitted aerosol had a size range favorable for lung deposition and could be measured reproducibly. Nevertheless, in vivo fluorescent imaging still revealed considerable differences between the mice in terms of the dose deposited and the distribution of powder over the lungs, suggesting that a certain biological variation in lung deposition is inevitable.

Behavioral paradigm for the evaluation of stimulation-evoked somatosensory perception thresholds in rats.

Intracortical microstimulation (ICMS) of the somatosensory cortex via penetrating microelectrode arrays (MEAs) can evoke cutaneous and proprioceptive sensations for restoration of perception in individuals with spinal cord injuries. However, ICMS current amplitudes needed to evoke these sensory percepts tend to change over time following implantation. Animal models have been used to investigate the mechanisms by which these changes occur and aid in the development of new engineering strategies to mitigate such changes. Non-human primates are commonly the animal of choice for investigating ICMS, but ethical concerns exist regarding their use. Rodents are a preferred animal model due to their availability, affordability, and ease of handling, but there are limited choices of behavioral tasks for investigating ICMS. In this study, we investigated the application of an innovative behavioral go/no-go paradigm capable of estimating ICMS-evoked sensory perception thresholds in freely moving rats. We divided animals into two groups, one receiving ICMS and a control group receiving auditory tones. Then, we trained the animals to nose-poke - a well-established behavioral task for rats - following either a suprathreshold ICMS current-controlled pulse train or frequency-controlled auditory tone. Animals received a sugar pellet reward when nose-poking correctly. When nose-poking incorrectly, animals received a mild air puff. After animals became proficient in this task, as defined by accuracy, precision, and other performance metrics, they continued to the next phase for perception threshold detection, where we varied the ICMS amplitude using a modified staircase method. Finally, we used non-linear regression to estimate perception thresholds. Results indicated that our behavioral protocol could estimate ICMS perception thresholds based on ~95% accuracy of rat nose-poke responses to the conditioned stimulus. This behavioral paradigm provides a robust methodology for evaluating stimulation-evoked somatosensory percepts in rats comparable to the evaluation of auditory percepts. In future studies, this validated methodology can be used to study the performance of novel MEA device technologies on ICMS-evoked perception threshold stability using freely moving rats or to investigate information processing principles in neural circuits related to sensory perception discrimination.

Interactions between physiology and behaviour provide insights into the ecological role of venom in Australian funnel-web spiders: Interspecies comparison.

Australian funnel-web spiders are iconic species, characterized as being the most venomous spiders in the world. They are also valued for the therapeutics and natural bioinsecticides potentially hidden in their venom molecules. Although numerous biochemical and molecular structural approaches have tried to determine the factors driving venom complexity, these approaches have not considered behaviour, physiology and environmental conditions collectively, which can play a role in the evolution, complexity, and function of venom components in funnel-webs. This study used a novel interdisciplinary approach to understand the relationships between different behaviours (assessed in different ecological contexts) and morphophysiological variables (body condition, heart rate) that may affect venom composition in four species of Australian funnel-web spiders. We tested defensiveness, huddling behaviour, frequency of climbing, and activity for all species in three ecological contexts: i) predation using both indirect (puff of air) and direct (prodding) stimuli; ii) conspecific tolerance; and iii) exploration of a new territory. We also assessed morphophysiological variables and venom composition of all species. For Hadronyche valida, the expression of some venom components was associated with heart rate and defensiveness during the predation context. However, we did not find any associations between behavioural traits and morphophysiological variables in the other species, suggesting that particular associations may be species-specific. When we assessed differences between species, we found that the species separated out based on the venom profiles, while activity and heart rate are likely more affected by individual responses and microhabitat conditions. This study demonstrates how behavioural and morphophysiological traits are correlated with venom composition and contributes to a broader understanding of the function and evolution of venoms in funnel-web spiders.

Startle Responses of Jorō Spiders (Trichonephila clavata) to Artificial Disturbance

The jorō spider (Trichonephila clavata, originally from east Asia) has been introduced in the southeastern United States, and is rapidly expanding this range, leading to questions about what facilitates this spread. Meanwhile, its cousin, the golden silk spider (T. clavipes), already has a range that covers most of the southeast. In an ongoing effort to understand the behavior of jorō spiders in their introduced range, we undertook the current project to evaluate how they react to perceived threats, which can inform us on how a species interacts with conspecifics, or how well it can tolerate anthropogenic disturbances. We collected mature females of both Trichonephila species, plus three locally common orb-weaving species in Georgia, and we evaluated the time spent immobile after experiencing a mild disturbance (a brief puff of air). We also collected similar “air puff response” data for five other North American species from the published literature. Collectively, the dataset totaled 453 observations of freezing behavior across 10 spider species. Comparing these data across species revealed that most spiders remained immobile for under a minute after the stimulus. Meanwhile, both Trichonephila spiders remained immobile for over an hour, which appears to be unprecedented, and suggests that spiders in this genus are the “shyest” ever documented. This reaction could also allow Trichonephila spiders to tolerate urban environments by remaining motionless throughout each disturbance instead of fleeing.

Persistence of auditory modulation of wind-induced escape behavior in crickets.

Animals, including insects, change their innate escape behavior triggered by a specific threat stimulus depending on the environmental context to survive adaptively the predators' attack. This indicates that additional inputs from sensory organs of different modalities indicating surrounding conditions could affect the neuronal circuit responsible for the escape behavior. Field crickets, Gryllus bimaculatus, exhibit an oriented running or jumping escape in response to short air puff detected by the abdominal mechanosensory organ called cerci. Crickets also receive a high-frequency acoustic stimulus by their tympanal organs on their frontal legs, which suggests approaching bats as a predator. We have reported that the crickets modulate their wind-elicited escape running in the moving direction when they are exposed to an acoustic stimulus preceded by the air puff. However, it remains unclear how long the effects of auditory inputs indicating surrounding contexts last after the sound is terminated. In this study, we applied a short pulse (200ms) of 15-kHz pure tone to the crickets in various intervals before the air-puff stimulus. The sound given 200 or 1000ms before the air puff biased the wind-elicited escape running backward, like the previous studies using the longer and overlapped sound. But the sounds that started 2000ms before and simultaneously with the air puff had little effect. In addition, the jumping probability was higher only when the delay of air puff to the sound was 1000ms. These results suggest that the cricket could retain the auditory memory for at least one second and alter the motion choice and direction of the wind-elicited escape behavior.

Association between Myopia and Glaucoma; A Cross-sectional Study

Myopia is a major cause of worldwide avoidable blindness and its prevalence increasing rapidly. Objective: To investigate the prevalence of glaucomatous optic nerve damage with various myopia levels as well as the relationship between myopia and glaucoma. Methods: A multi-centered cross-sectional study was conducted from January 2022 to July 2022. 250 individuals between the ages of 40 and 65 were recruited using non-probability purposive sampling technique. Mild, moderate and severe degree of myopia who had never had any surgery were included. All subjects underwent refraction and the optic disc ratio was assessed by slit lamp biomicroscopy, perimetry was performed to evaluate the visual field defects and IOP was determined using air puff tonometer. Frequency of glaucoma indicated by presence of visual field defects, glaucomatous optic disc. SPSS software was used for data analysis. Results: 145 (58%) of the 250 total subjects were female and 105(42%) were male. 67 (26.8%) people had refractive errors of mild myopia up to 3D. While 85 (34%) had a severe degree of myopia (refractive error greater than 6D) and 98 (39.2%) had a moderate degree. No intragroup's intraocular pressure showed a significantly distinct configuration. Age-related VF anomalies (a larger blind region, a vertical cup to disc ratio, and an unjustified defect) were associated with both glaucoma and high myopia. Findings from the study indicated that glaucoma risk increased for those with high myopia (p=0.001). Conclusion: High myopia is strongly associated with glaucomatous changes and a high prevalence of optic disc damage.

Mesolimbic dopamine release precedes actively sought aversive stimuli in mice

In some models, animals approach aversive stimuli more than those housed in an enriched environment. Here, we found that male mice in an impoverished and unstimulating (i.e., boring) chamber without toys sought aversive air puffs more often than those in an enriched chamber. Using this animal model, we identified the insular cortex as a regulator of aversion-seeking behavior. Activation and inhibition of the insular cortex increased and decreased the frequencies of air-puff self-stimulation, respectively, and the firing patterns of insular neuron ensembles predicted the self-stimulation timing. Dopamine levels in the ventrolateral striatum decreased with passive air puffs but increased with actively sought puffs. Around 20% of mice developed intense self-stimulation despite being offered toys, which was prevented by administering opioid receptor antagonists. This study establishes a basis for comprehending the neural underpinnings of usually avoided stimulus-seeking behaviors.

Stimulating olfactory epithelium mitigates mechanical ventilation-induced hippocampal inflammation and apoptosis.

Mechanical ventilation (MV), as a life-saving procedure in critical patients, is a risk factor to develop of neurocognitive dysfunction and triggers of inflammation and apoptosis in the brain. Since diversion of breathing route to the tracheal tube diminishes brain activity entrained by physiological nasal breathing, we hypothesized that simulating nasal breathing using rhythmic air-puff (AP) into the nasal cavity of mechanically ventilated rats can reduce hippocampal inflammation and apoptosis in association with restoring respiration-coupled oscillations. We found that stimulating olfactory epithelium through applying rhythmic nasal AP, in association with reviving respiration-coupled brain rhythm, mitigates MV-induced hippocampal apoptosis and inflammation involving microglia and astrocytes. The current translational study opens a window for a novel therapeutic approach to reduce neurological complications induced by MV.

Study protocol of an investigation of attention and prediction error as mechanisms of action for latent inhibition of dental fear in humans

BackgroundEvidence suggests that dental anxiety and phobia are frequently the result of direct associative fear conditioning but that pre-exposure to dental stimuli prior to conditioning results in latent inhibition of fear learning. The mechanisms underlying the pre-exposure effect in humans, however, are poorly understood. Moreover, pain sensitivity has been linked to dental fear conditioning in correlational investigations and theory suggests it may moderate the latent inhibition effect, but this hypothesis has not been directly tested. These gaps in our understanding are a barrier to the development of evidence-based dental phobia prevention efforts.MethodsHealthy volunteers between the ages of 6 and 35 years will be enrolled across two sites. Participants will complete a conditioning task in a novel virtual reality environment, allowing for control over pre-exposure and the examination of behaviour. A dental startle (a brief, pressurized puff of air to a tooth) will serve as the unconditioned stimulus. Using a within-subjects experimental design, participants will experience a pre-exposed to-be conditioned stimulus, a non-pre-exposed to-be conditioned stimulus, and a neutral control stimulus. Two hypothesized mechanisms, changes in prediction errors and attention, are expected to mediate the association between stimulus condition and fear acquisition, recall, and retention. To ascertain the involvement of pain sensitivity, this construct will be measured through self-report and the cold pressor task.DiscussionDental phobia negatively affects the dental health and overall health of individuals. This study aims to determine the mechanisms through which pre-exposure retards conditioned dental fear acquisition, recall, and retention. A randomized control trial will be used to identify these mechanisms so that they can be precisely targeted and maximally engaged in preventative efforts.

In-vivo high-speed biomechanical imaging of the cornea using Corvis ST and digital image correlation

In-vivo corneal biomechanical characterization has gained significant clinical relevance in ophthalmology, especially in the early diagnosis of eye disorders and diseases (e.g. keratoconus). In clinical medicine, the air-puff-based tonometers such as Ocular Response Analyzer (ORA) and Corvis ST have been used in the in-vivo biomechanical testing. In the test, the high-speed dynamic deformation of the cornea under air-puff excitation is analyzed to identify the abnormities in the morphological and biomechanical properties of the cornea. While most existing measurements reflect the overall corneal biomechanical properties, in-vivo high-speed strain and strain rate fields at the tissue level have not been assessed. In this study, 20 subjects were classified into two different groups: the normal (NORM, N = 10) group and the keratoconus (KC, N = 10) group. Image sequences of the horizontal cross-section of the human cornea under air puff were captured by the Corvis ST tonometer. The macroscale mechanical response of the cornea was determined through image analysis. The high-speed evolution of full-field corneal displacement, strain, velocity, and strain rate was reconstructed using the incremental digital image correlation (DIC) approach. Differences in the parameters between the NORM and KC groups were statistically analyzed and compared. Statistical results indicated that compared with the NORM group, the KC corneas absorbed more energy (KC: 8.98 ± 2.76 mN mm; NORM: 4.79 ± 0.62 mN mm; p-value <0.001) with smaller tangent stiffness (KC: 22.49 ± 2.62 mN/mm; NORM: 24.52 ± 3.20 mN/mm; p-value = 0.15) and larger maximum deflection (KC: 0.99 ± 0.07 mN/mm; NORM: 0.92 ± 0.06 mN/mm; p-value <0.05) on the macro scale. Further, we also observed that The maximum displacement (KC: 1.17 ± 0.06 mm; NORM: 1.06 ± 0.07 mm; p-value <0.005), velocity (KC: 236 ± 29 mm/s; NORM: 203 ± 17 mm/s; p-value <0.01), shear strain (KC: 24.43 ± 2.59%; NORM: 20.26 ± 1.54%; p-value <0.001), and shear strain rate (KC: 69.74 ± 11.99 s−1; NORM: 54.84 ± 3.03 s−1; p-value <0.005) in the KC group significantly increased at the tissue level. This is the first time that the incremental DIC method was applied to the in-vivo high-speed corneal deformation measurement in combination with the Corvis ST tonometer. Through the image registration using incremental DIC analysis, spatiotemporal dynamic strain/strain rate maps of the cornea can be estimated at the tissue level. This is constructive for the clinical recognition and diagnosis of keratoconus at a more underlying level.

Noncontact Detection Method for Food Texture Assessment Based on Air Puff Combined With Structured Light Imaging

Given the shortcomings of subjectivity and destructiveness associated with traditional methods of measuring food texture parameters (such as fruit firmness and meat tenderness) when using a texture meter, a non-contact measurement method utilizing an Air-puff combined with Structured Light Imaging (ASLI) was proposed in this study. First, the finite element simulation method was used to simulate the airflow impact model and optimize the ranges of the angle and distance parameters. The detection device was then developed, and binocular 3D phenotype acquisition and 3D feature extraction algorithms were investigated. Denoising, point cloud segmentation, greedy projection triangulation, Delaunay triangulation, and surface fitting algorithms were used to process the point cloud, and concave parameters such as depth, mapping area, surface area, and volume of the concave area on the beef surface were obtained. Finally, four typical samples with different meat (beef and chicken) and fruit (kiwifruit and peach) parameters were tested. Five machine learning methods were used to model and analyze the correlation among texture parameters. The results revealed that the model established by the ensemble learning modeling method with extracted concave parameters possessed the highest accuracy. The prediction accuracy of the shear force values of the beef and chicken samples were 0.92 and 0.91. The accuracy of meat and fruit grading was 0.942 and 1.0. Therefore, the non-contact detection method proposed in this study to determine food texture characteristics based on airflow can be used to replace the traditional texture analyzer in food engineering and exhibits good application potential.

Corneal endothelial ring following the implantation of toric implantable collamer lenses with a central hole: a case report

BackgroundTo report a case of a corneal endothelial ring after toric implantable collamer lens (TICL, V4C) implantation in the right eye of a patient.Case presentationA 36-year-old woman with refractive errors of -8.00 DS/-2.00 DC * 8° in the right eye and − 6.50 DS/-1.75 DC * 177° in the left eye developed a corneal endothelial ring in the right eye on the first day after receiving TICLs implantation for treatment of high myopic astigmatism, which has not been previously reported as a complication of ICLs implantation. At 1 day postoperatively, the uncorrected distance visual acuity (UDVA) was 20/16, the intraocular pressure as measured by non-contact tonometry was 16.9 mmHg, and the vault as measured by anterior segment optical coherence tomography was 1238 μm. The eye was quiet and there was no unusual anterior chamber reaction. However, slit-lamp examination revealed an endothelial annular lesion of approximately 0.4 mm in diameter in the central part of the cornea, which was gray-white in color. The shape of the ring was the same as that of the central hole of the TICL. Specular microscopy showed that the mean endothelial cell density (ECD) of the ring significantly decreased to 1442 ± 263 cells/mm2, while the other part was still normal (2852 ± 103 cells/mm2). After 9 days of corticosteroid treatment and intense lubrication, the patient had a clear cornea, increased ECD (1532 ± 653 cells/mm2), and a good UDVA (20/16).ConclusionThis case suggests that a few hours after ICL V4C implantation, with a large vault, corneal displacement caused by an air puff would make the endothelium close to or even contact the ICL, producing a corneal endothelial ring. After ruling out various possible factors, we speculated that the endothelial ring was developed due to the non-contact tonometer air puff before slit-lamp evaluation, and this phenomenon was recorded by Corvis, which confirmed that the cornea could come in contact with the ICL due to gas shock. This “contact” may cause transient corneal endothelial damage.

Experimental Evaluation of Shale Oil Development Effectiveness by Air Injection

In recent years, as an important part of unconventional resources, the effective development of shale oil has been a key area of research in petroleum engineering. Given the widespread availability and low cost of air, the evaluation of air injection in shale reservoirs is a topic worth exploring. This paper analyzes the production performance of different methods of air injection development in the shale reservoir, including air flooding and air huff and puff (HnP), based on full-diameter core air injection experiments. Meanwhile, the characteristics of the residual oil and produced oil are revealed by forming a systematic evaluation method that includes nuclear magnetic resonance (NMR), laser scanning confocal microscopy (LSCM), and gas chromatographic (GC) analysis. The results show that air flooding development is characterized by early gas breakthrough, long oil production period, and “L” shape oil production decline; while air HnP is characterized by first producing gas and then producing oil, rapid oil production, and high oil recovery efficiency in the first round. Compared with air flooding, the replacement efficiency of the first round of air HnP is significantly higher, demonstrating higher feasibility of air HnP in the early stages of development, although the cumulative recovery of three rounds air HnP (17.17%) is lower than that of air flooding (23.36%). The large pores (T2 &gt; 10 ms) are the main source of air injection recovery, while the residual oil is mainly concentrated in the medium pores (1–10 ms). Air injection development has a higher recovery factor for light components (C15−), resulting in a higher level of heavy components in the residual oil. This paper discusses the feasibility and development effectiveness of air injection in shale oil reservoirs, and its development characteristics are further clarified.

Studies of Putative Human Bioenergy Using a Torsion Pendulum with a Metal Chain-Link Support instead of a Nylon Filament Support

Earlier experiments have established that a torsion pendulum consisting of a steel mesh hemisphere suspended by a nylon filament above a human subject is capable of detecting and collecting data that may represent human bioenergy. Among the effects observed are a wide range of subject-induced rotational frequencies of the pendulum and displacement of the pendulum from its natural center of oscillation. The nylon filament support confers the properties of a simple harmonic oscillator (sho) to the pendulum. The resulting sho swings of the pendulum obscure smaller swings that correspond to subject effects on the pendulum. For this work, it was desired to modify the pendulum to reduce or eliminate the sho oscillatory swings. A proposed modification was to replace the nylon filament with a length of chain. The idea was that the chain would confer properties of an ‘energy well’ to the pendulum. Rotational forces exerted on the chain-supported pendulum would cause the chain to twist and thus rise up the side of the energy well. Ideally, the only restoring force would be the tendency of the twisted links to untwist, so as to drop back down to the bottom of the energy well. This strategy was successful. Control experiments in which the chain-supported pendulum was stimulated to rotational motion by air puffs showed a rapid deflection of the pendulum, which represented traveling up the side of the energy well. The deflected pendulum then immediately returned to its original position and remained there, with no sho oscillations being evident. This is consistent with the chain-link pendulum conforming to the characteristics of an energy well. The chain-supported pendulum was used to assess subject effects on the pendulum. The basic pattern of the subject effects resembled those obtained with a nylon filament-supported pendulum, except the large sho swings that are a feature of the filament-supported pendulum, were absent from the effects observed by the chain-supported pendulum. Thus, for the first time, the pattern of subject-induced effects could be observed, measured, and analyzed without being obscured by sho oscillations. Soon after the subject was seated under the pendulum, its rotational motion drove the pendulum rotational position up one side of the energy well, where it stayed throughout the experiment. This establishes that the force is a spiral force, which conforms to our earlier observations. The now-visible underlying subject-induced oscillations are nuanced and sophisticated and are reminiscent of the complexity of music or speech. Moreover, these oscillations encompass a range of very low frequencies, from less than 0.01 Hz to 0.15 Hz. The frequency amplitudes rise dramatically at the lowest frequencies, suggesting the existence of additional even lower frequencies; but if they exist, the current pendulum cannot detect them. The frequency amplitudes toward the upper end do not fade away completely, suggesting that what is observed represents what there is. These frequencies are much lower than what is detected by electrodes attached to the scalps of subjects which measure minute voltage fluctuations called ‘brain waves.’ These voltage-related brain waves range from 0.5-42 Hz. Low frequency humpback whale sounds, often attributed to being a means of long-range communication, range from 30-8,000 Hz. As far as we know, the low frequencies observed with the chain-supported pendulum are unprecedented. As of now, the nature and origin of the subject effects measured by the nylon filament and chain-supported pendulums are not known. Accumulating evidence argues that they are not merely subject-induced thermal convection currents, but some other form of energy that originates from the subject. As an energy of very low frequency, it could be expected to propagate over long distances, reminiscent of low frequency whale sounds. This article addresses these and other issues.

Perturbed astrocyte Ca2+ signaling in a diet‐based mouse model of small cerebral vessel disease

AbstractBackgroundThe hyperhomocysteinemia (HHcy) diet model of small cerebral vessel disease exhibits vascular inflammation, cerebral hypoperfusion, impaired neurovascular coupling, synapse dysfunction, and cognitive decline. Pathological changes in astrocyte structural features have also been noted, but functional astrocyte phenotypes have not been characterized. Here, we assessed Ca2+ signaling in individual astrocytes and astrocyte networks in barrel cortex of mice, pretreated with control or HHcy diet. Investigations were performed in fully awake mice to avoid confounding interactions between anesthetics, neural circuit activity, and vasoactive factors.MethodAdult C57/BL6 mice were fed for 15 weeks with control chow, or chow deficient in vitamins B6/B12 and enriched in methionine (HHcy diet). At week 11‐12, mice were injected with AAV‐Gfa104‐lck‐GCaMP6f into barrel cortex, followed by craniotomies and installation of a glass cranial windows with headmounts. Three weeks later, fully awake mice were head‐mounted under a two photon microscope to assess GCaMP6/Ca2+ transient activity in barrel cortex astrocytes during a 10 minute baseline (spontaneous activity) and also before, during, and air puff stimulation of contralateral whiskers (10Hz, 10 sec) . Mean Ca2+ transient amplitudes, transient rise/decay times, and number of transients per region of interest (ROI) were measured and averaged across the field of view (FOV). Functional relationships between multiple ROIs within the FOV were assessed to evaluate astrocyte network activityResultSpontaneous Ca2+ transients were comparable in amplitude and rise/decay kinetics across diet conditions. However, the number of transients per ROI was reduced in HHcy diet mice. Whisker stimulation evoked a primary Ca2+ elevation per ROI followed 10‐15 seconds later by a smaller amplitude Ca2+‐“aftershock”. Evoked Ca2+ signals were highly coordinated across ROIs within the FOV. However, the number of active ROIs and the functional connectivity between ROIs were significantly reduced in HHcy vs. control diet mice. Despite these network deficits, evoked Ca2+ transient amplitudes and aftershocks in individual ROIs were significantly larger with faster activation/decay kinetics in HHcy mice.ConclusionThe results suggest that altered astrocyte Ca2+ signaling, as a result of vascular pathology, may play an important role in the dynamic interplay between cerebral blood flow and neuronal activity, leading to overall neural dysfunction and cognitive impairment.

Corneal Tonometric and Morphological Changes in Patients with Acromegaly.

(1) Purpose: This study aimed to investigate the changes in Reichert Ocular Response Analyzer (ORA) parameters, corneal endothelium parameters, central corneal thickness (CCT), and intraocular pressure (IOP) before and after the transsphenoidal resection of pituitary adenoma in patients with acromegaly. (2) Methods: This was a single-center, prospective, interventional study. Twenty patients with newly diagnosed acromegaly were examined before and 19 ± 9 months after transsphenoidal resection. The participants underwent a comprehensive ophthalmological examination including pneumatic IOP (IOP air puff), Goldmann applanation tonometry (IOP GAT), CCT measured using the iPac pachymeter (CCTUP), IOP value corrected for CCTUP using the Ehlers formula (IOPc) ORA measurements included corneal hysteresis (CH), corneal resistance factor (CRF), corneal-compensated IOP (IOPcc), and Goldmann-correlated IOP (IOPg). CCT from non-contact specular microscopy (CCTNSM), the number of endothelial cells (CD) per mm2, and average cell size (AVG) were determined with non-contact specular microscopy. (3) Results: A statistically significant decrease was observed in CCTUP (p = 0.007), and IOP air puff (p = 0.012) after surgery. Moreover, we noted a statistically significant increase in CD (p = 0.001), and a statistically significant decrease in AVG (p = 0.009) and CCTNSM (p = 0.004) after surgery. A statistically significant decrease was also observed in IOPg (p = 0.011), CH (p = 0.016), and CRF (p = 0.001) after surgery. The mean value of IOP GAT and IOPc was lower after the surgery. However, the difference was not statistically significant. (4) Conclusions: Our study revealed significant changes in biomechanics, corneal endothelium, CCT and IOP after pituitary adenoma resection in patients with acromegaly. It proves that the eye might be sensitive to long-term overexposure to growth hormone (GH) and insulin-like growth factor-1 (IGF-1). We suggest that disease activity be taken into consideration on ophthalmological examination.

Migraine Type-Dependent Patterns of Brain Activation After Facial and Intranasal Trigeminal Stimulation

In migraine, the trigeminal nerve is intimately involved in the pathophysiology of the disease. We hypothesized that alterations in the sensory trigeminal activation in migraine would be reflected by EEG-derived event-related potentials (ERP). We aimed to investigate differences in the temporal and spatial processing of trigeminal stimuli between interictal migraine patients and healthy subjects. ERP to trigeminal stimuli were recorded at 128-channels to allow localization of their cortical sources with high temporal resolution. Seventeen patients with episodic migraine without aura, 17 subjects with episodic migraine with aura, and 17 healthy subjects participated in the study. The first branch of the trigeminal nerve was stimulated using intranasal chemical (CO2), cutaneous electrical, and cutaneous mechanical (air puff) stimuli. Analyses were performed with regard to micro-state segmentation, ERP source localization, and correlation with the patients’ clinical characteristics. Topographical assessments of EEG configurations were associated with the pathological condition. The source analysis revealed altered trigeminal-sensory response patterns in the precuneus, temporal pole, and cerebellum for both migraine groups during the interictal phase. The estimated current source density was positively correlated with migraine disease duration, indicating brain functional and structural changes as a consequence of the disease. Hyperactivity of the cerebellar posterior lobe was observed as a specific trigeminal response of migraine patients with aura. In conclusion, our results suggest the presence of brain changes accompanying the advancement of migraine as an expression of dysfunctional central pain processing. Hence, we identified EEG patterns in response to mechano-/chemosensory stimuli that can serve as biomarkers of migraine.

Validity of aerosolization detection with an air quality indicator in noncontact tonometry using corneal phantoms

Précis Using a controlled experimental design with corneal phantoms, this study provides evidence of the lack of validity of a static air quality indicator, previously used to characterize aerosolization during dynamic noncontact tonometry. Purpose To evaluate the accuracy of aerosol concentrations reported by an air quality indicator (AQI) following an air puff from a noncontact tonometer using non-aerosolizing corneal phantoms. Methods Three rubber corneal phantoms of different stiffnesses were used to represent varying intraocular pressure (IOP) values. No liquid components and therefore no aerosol-generating potential was present. Reported concentrations of particulate matter (PM) having diameter less than 2.5 and 10µm, respectively PM2.5 and PM10, were recorded using an AQI before and during an air puff generated using noncontact tonometry. The effects of covariates IOP and sensor location on changes to air quality measurements from the baseline were evaluated using analysis of variance. Monte Carlo simulations were used to determine the likelihood of observing published trends by chance. The statistical significance threshold was p&amp;lt;0.05. Results No correlations were found between PM2.5 and IOP or location. Reported concentrations of PM10 depended significantly on both IOP (p=0.0241) and location (p=0.0167). Monte Carlo simulations suggest the likelihood of finding a spurious positive correlation between IOP and PM at the upper same location are 53% and 92% for PM2.5 and PM10, respectively, indicating the AQI has systematic bias resulting from non-aerosol sources. Conclusions We were able to reproduce the published correlation between reported aerosol concentration and IOP in non-contact tonometry using dry rubber phantoms in place of living corneas with tear films. In this study, we demonstrated that published correlations linking NCT to tear film aerosolization were artifacts of the measurement technique.