Tissue Window Research Articles

Accidental ingestion of a fractured piece of orthodontic aligner: a case report

BackgroundIngestion and aspiration of orthodontic devices are rare occurrences, typically associated with components such as expansion keys, archwire segments, dislodged fixed appliances (including brackets, buccal tubes, and bands), as well as fractured metal or plastic appliances. This article describes the clinical diagnosis and treatment process of a case of accidental ingestion of a fractured piece of orthodontic aligner.Case presentationA 31-year-old female under orthodontic treatment by aligners accidentally ingested a fractured piece of the aligner. The special difficulty of this case is that the transparent orthodontic aligner has a low radiopacity. At the beginning, no foreign body was found in the commonly used soft tissue window, causing difficulty in its location until greyscale was adjusted to lung window. The 2-centimeter fractured piece was taken out under anesthesia and endoscopic surgery.ConclusionMaterials with low radiopacity should be read with a lower grayscale range. Fractured orthodontic appliances with low retention force should not continue to be worn until consultation with attending doctor.

Multiwavelength highly transient stimulated Raman scattering on dual Raman modes in Sr(MoO4)0.8(WO4)0.2 and Sr(MoO4)0.4(WO4)0.6.

For the first time to our knowledge, multiwavelength, highly transient, single-pass stimulated Raman scattering with a low wavelength spacing on dual (stretching and bending) Raman modes in Sr(MoO4)0.8(WO4)0.2 and Sr(MoO4)0.4(WO4)0.6 solid solutions in a range of 1000-1300 nm (transparence window of biological tissue) under ultrafast chirped pulse laser pumping is comparatively investigated in the interests of multicolor two-photon imaging of a living tissue. For both the solid solutions, the optimum range (1-5 ps) of chirped pump pulse durations for multiwavelength Raman conversion on dual Raman modes was wider than for SrMoO4 (2-3 ps) due to the higher integral cross section of the bending Raman mode. Higher efficient SRS conversion took place at negative chirping of the pump pulse with its stretching from 0.25 ps up to 5 ps due to the compensation of a positive chirp caused by nonlinear phase modulation with total Raman conversion efficiency of up to 36% for Sr(MoO4)0.8(WO4)0.2 and 49% for Sr(MoO4)0.4(WO4)0.6. The highest number (five) of Stokes components in the desired range (1000-1300 nm) was observed in the optimum Sr(MoO4)0.4(WO4)0.6 solid solution, which has the Raman modes with comparable intensities.

Postoperative Orbital Morphology Observations Following Fronto-Orbital Advancement and Cranial Vault Remodeling in Patients With Unilateral Coronal Synostosis.

Observations of preoperative and postoperative orbital morphology following fronto-orbital advancement and cranial vault remodeling (FOA and CVR) in patients with unilateral coronal synostosis (UCS). This retrospective cohort included patients diagnosed with unilateral coronal synostosis and treated with fronto-orbital advancement and cranial vault remodeling at the Children's Hospital of Fudan University. The orbital height, orbital width, and orbital volume were obtained from head 3-dimensional computed tomography of preoperation and postoperation. The DICOM data of CT were then imported into mimics research version 21.0. The authors measured OH and OW according to the bony landmarks, then reset the parameters of the soft tissue window, and conducted a 3-dimensional reconstruction of the orbital soft tissue to get OV. The preoperative and postoperative measurements of the intact side were compared with the affected side, respectively. Statistical analysis was performed using SPSS version 25.0 (Ρ=0.05). Twelve patients with UCS (5 male, 7 female) meeting criteria were included in the study. There were 4 patients with UCS on the left and 8 on the right. The average age at initial surgery was 19.50 months. Before the operation, the data of the intact side and the affected side were compared, respectively, and the difference was found to be significant in OH (Ρ=0.005) and OW (Ρ=0.005), while the OV (Ρ=0.106) was not statistically significant. After procedures of FOA and CVR, the data of the intact side and the affected side were compared, respectively, the significant difference was found in OV (Ρ=0.002), while not in OH (Ρ=0.060) or OW (Ρ=0.066). After undergoing the operation of FOA and CVR, the OH and OW of the ipsilateral and contralateral sides of patients with UCS were basically symmetrical, while the volume of the affected orbit was still relatively smaller.

Symptomatic and Morphometric Analysis of Lumbosacral Transitional Vertebrae: Assessments by Age and Gender

Aim: Lumbosakral transitional vertebrae (LSTV) are anatomical variations where a vertebra exhibits characteristics of both lumbar and sacral vertebrae. This study aims to assess anatomical changes in LSTV patients by measuring intervertebral disc height (IVDh), vertebral foramen anteroposterior diameter (FVAPd), and intervertebral foramen height (FIVh), with consideration of age and gender differences. Materials and Methods: This retrospective study included 274 patients diagnosed with LSTV. All MRI images were acquired with a 1.5T MRI machine and a 32-channel lumbar coil. The presence of LSTV, forming the morphological data, was identified from coronal and sagittal reformat images and was classified as either lumbarization or sacralization. Morphometric data (IVDh, FIVh and FVAPd) were acquired from axial, sagittal, and coronal planes using both soft tissue and bone window settings. Results: The mean patient age was 41.6±13.0 years, with a female majority (55.8%). LSTV was predominantly lumbarization (96.4%), with sacralization in the remaining cases. The overall mean FVAPd was 11.2±2.4 mm, mean IVDh was 9.1±1.8 mm, and mean FIVh was 18.8±2.4 mm on the right and 19.1±2.4 mm on the left. IVDh levels were consistent across age groups, while FVAPd values were similar between genders. Patients aged 40 and under had higher FVAPd and FIVh levels, and male patients had higher IVDh and FIVh levels compared to females. Conclusions: The morphometric characteristics of LSTV may vary according to age and gender. Considering these factors in accurately identifying the anatomical variations of LSTV may play a significant role in determining appropriate treatment and management strategies.

A Pervasive Approach for Determining the Optimal Tissue Windows for Near‐Infrared Fluorescence Imaging

A Pervasive Approach for Determining the Optimal Tissue Windows for Near‐Infrared Fluorescence Imaging

Temperature dependence of the near infrared absorption spectrum of single-wall carbon nanotubes dispersed by sodium dodecyl sulfate in aqueous solution: experiments and molecular dynamics study.

Single-wall carbon nanotubes (SWCNT) dispersed in water with the help of sodium dodecyl sulfate (SDS) surfactants exhibit a temperature dependent near infrared (NIR) exciton spectrum. Due to their biocompatibility and NIR spectrum falling within the transparent window for biological tissue, SWCNTs hold potential for sensing temperature inside cells. Here, we seek to elucidate the mechanism responsible for this temperature dependence, focusing on changes in the water coverage of the SWCNT as the surfactant structure changes with temperature. We compare optical absorption spectra in the UV-Vis-IR range and fully atomistic molecular dynamics (MD) simulations. The observed temperature dependence of the spectra for various SWCNTs may be attributed to changes in the dielectric environment and its impact on excitons. MD simulations reveal that the adsorbed SDS molecules effectively shield the SWCNT, with ~ 70% of water molecules removed from the first two adlayers; this coverage shows a modest temperature dependence. Although we are not able to directly demonstrate how this influences the NIR spectrum, this represents a potential pathway given the strong influence of the water environment on the excitons in SWCNTs. Optical absorption measurements were carried out in the UV-Vis-NIR range using a Varian Cary 5000 spectrophotometer in a temperature-controlled environment. PeakFit™ v. 4.06 was used as peak-fitting program in the spectral range 900-1400nm (890-1380meV) as a function of the temperature. Fully atomistic molecular dynamics simulations were conducted using the NAMD2 package. The CHARMM force field comprising two-body bond stretching, three-body angle deformation, four-body dihedral angle deformation, and nonbonded interactions (electrostatic and Lennard-Jones 6-16 potentials) was employed.

Study on the consistency between CT hounsfield units and MRI evaluation of preoperative cervical paraspinal muscular fat infiltration in patients undergoing ACDF

ObjectiveTo explore the feasibility of applying CT Hounsfield Units (HUs) for the assessment of preoperative paraspinal muscle fat infiltration (FI) in different segments in patients who underwent anterior cervical discectomy and fusion (ACDF). To compare the consistency of preoperative paraspinal muscle FI evaluations using MRI and those via CT HUs in patients who underwent ACDF surgery.MethodsNinety-five patients (45 males and 50 females, aged 37‒71 years) who received CT and MRI examinations and underwent ACDF surgery were retrospectively analyzed. In the axial T2-weighted MR images at the median level of the C3/4, C4/5, and C5/6 segments, regions of interests (ROIs) were delineated along the boundaries of the cervical multifidus (MF) and semispinalis cervicis (Scer) muscles. Using the threshold tool in ImageJ software, areas of fat tissue and intermuscular septa within the ROI were quantified. The effective cross-sectional area (ECSA) for each side was obtained by subtracting the areas of fat tissue and intermuscular septa from the total ROI area. The ratio of the fat tissue area to the CSA was then calculated to determine the initial FI value. The depth of subcutaneous fat from the midline spinous process to the epidermis at the median plane of the C4/5 intervertebral disc was measured. The initial FI values were then divided by the depth of fat to determine the post-correction FI value. Using the Picture Archiving and Communication System (PACS), at identical segments and planes, ROIs were delineated using the same method as in MRI under a standard soft tissue window (width of 500 HU, level of 60 HU). The CT HU values were measured within these defined areas. The CT HU values from both sides are summed to obtain the total HU value for the segment. According to whether the measurement results of two sets of data follow a normal distribution, Pearson’s test or Sperman’s test was used to analyze the correlation.ResultsOn MRI, a statistically significant difference was observed in the post-correction FI only at the C3/4 segment compared to the other two segments (P < 0.05). No significant difference in the post-correction FI between the C4/5 and C5/6 segments was noted (P > 0.05). The CT HU results showed a substantial discrepancy between C3/4 and C4/5 segments and between C3/4 and C5/6 segments (P < 0.05), whereas no statistically significant difference was found in the CT HU value between the C4/5 and C5/6 segments (P > 0.05). The consistency analysis revealed a relatively strong correlation between the post-correction FI and CT HU values of the C3/4 and C4/5 segments. Furthermore, a strong correlation was detected in the variations in the measurement outcomes at the C5/6 segment.ConclusionPatients requiring surgical treatment for the cervical spine exhibit varying degrees of FI in paraspinal muscles across different locations and segments. Evaluating the degree of FI in the paraspinal muscles of the cervical spine through CT HU values is feasible. There is considerable consistency between the post-correction FI assessed under MRI and the measurements of CT HU values in evaluating the FI of paraspinal muscles in the cervical spine.

Comparative study of orbital volumes according to multispiral computed tomography data

BACKGROUND: It is believed that accurate reconstruction of the correct anatomy of the orbital bony walls, restoration of symmetry and volume are necessary for a favorable functional prognosis and elimination of an aesthetic defect. The main problem when estimating orbital volume is its complex anatomy. Scientists use various methods to determine orbital volume, and in reviews comparing various methods for calculating orbital volumes, there is no data on which orbital volumetric method is the most accurate, since each of them has both advantages and disadvantages. AIM: The aim of this study is the analysis and the comparison of orbital volumes according to multispiral computed tomography data of healthy patients without bone-traumatic changes of orbital walls. MATERIALS AND METHODS: To measure the volume of orbits, 50 random patients were selected who were examined in the radiology department No. 2 of the University Clinical Hospital No. 1 of the Sechenov University from 2023 to 2024 and who underwent multispiral computed tomography of the facial skeleton for indications unrelated to orbital conditions. Computed tomography data from 25 women and 25 men of different ages (from 18 to 85 years old) were analyzed. A total of 8 groups were formed depending on gender and age: group 1 — women 18–25 years old, group 2 — men 18–25 years old, group 3 — women 26–35 years old, group 4 — men 26–35 years old, group 5 — women 36–50 years old, group 6 — men 36–50 years old, group 7 — women 51 and older, group 8 — men 51 and older. Multispiral computed tomography of the facial skeleton was performed using the Aquilion One 640 CT scanner (Japan) with 0.5 slice thickness in bone and soft tissue windows, to be able to calculate orbital volumes at the workstation, all bone contours of the orbits were marked on each axial slice, starting from the upper wall to the bottom of the orbit with a representation of the orbital volumes in ml. RESULTS: The difference in the volumes of the right and left orbits of 0.5 ml or more was detected in 5 women out of 25 cases, among men the difference was present in 12 cases out of 25; a difference in volumes of more than 1 ml was noted in 1 woman and 2 men; a difference of more than 1.5 ml was not observed in any study group. The orbital asymmetry coefficient in women ranged from 0 ml to 1.21 ml, in men — from 0.08 ml to 1.19 ml, in women, the average volume of both orbits is less than in men. It was also detected that the volume of orbits increases with age, both in men and women. CONCLUSIONS: Considering that the majority of patients had differences in orbital volumes of up to 1.0 ml, we agree with studies that indicate the possibility of using a healthy contralateral orbit as a guideline when planning reconstructive surgery. However, for planning surgical treatment, it is recommended to use manual contouring, as this allows the most accurate reproducibility of the bone boundaries of the orbit, although it requires more time than semi- and automatic segmentation. Also, the advantages of the used method for calculating the volumes of orbits in this study include reproducibility on any workstation from different manufacturers, since the method is carried out on a standard tomograph workstation and does not require any additional software.

Nonlinear dynamics of femtosecond laser interaction with the central nervous system in zebrafish

Understanding the photodamage mechanism underlying the highly nonlinear dynamic of femtosecond laser pulses at the second transparent window of tissue is crucial for label-free microscopy. Here, we report the identification of two cavitation regimes from 1030 nm pulses when interacting with the central nervous system in zebrafish. We show that at low repetition rates, the damage is confined due to plasma-based ablation and sudden local temperature rise. At high repetition rates, the damage becomes collateral due to plasma-mediated photochemistry. Furthermore, we investigate the role of fluorescence labels with linear and nonlinear absorption pathways in optical breakdown. To verify our findings, we examined cell death and cellular responses to tissue damage, including the recruitment of fibroblasts and immune cells after irradiation. These findings contribute to advancing the emerging nonlinear optical microscopy techniques and provide a strategy for inducing precise, and localized injuries using near-infrared femtosecond laser pulses.

Intense charge transfer plasmons in golden nanoparticle dimers connected by conductive molecular linkers.

Golden nanoparticle dimers connected by conjugated molecular linkers 1,2-bis(2-pyridyl)ethylene are produced. The formation of stable dimers with 22nm diameter nanoparticles is confirmed by transmission electron microphotography. The possibility of charge transfer through the linkers between the particles in the dimers is shown by the density functional theory calculations. In addition to localized plasmon resonance of solitary nanoparticles with a wavelength of 530nm, the optical spectra exhibit a new intense absorption peak in the near-infrared range with a wavelength of ∼780nm. The emergent absorption peak is attributed to the charge-transfer plasmon (CTP) mode; the spectra simulated within the CTP developed model agree with the experimental ones. This resonant absorption may be of interest to biomedical applications due to its position in the so-called transmission window of biological tissues. The invitro heating of CTP dimer solution by a laser diode with a wavelength of 792nm proved the efficiency of CTP dimers for achieving a temperature increase of ΔT = 6 °C, which is sufficient for hyperthermia treatment of malignant tumors. This indicates the possibility of using hyperthermia to treat malignant tumors using the material we synthesized.

Evaluation of Head Height After Endoscopic Strip Craniectomy and Orthotic Therapy for Sagittal Craniosynostosis

Background: Achievement of normal head shape is one of the primary goals of all treatment modalities for craniosynostosis, in addition to maintenance of normal intracranial pressure and allowing normal brain development. Pre- and postoperative quantification of head shape in sagittal craniosynostosis has largely relied on cephalic index (width divided by anterior-posterior length of skull). However, many infants with sagittal craniosynostosis have a head that is short in addition to long and narrow. Height is not captured by the cephalic index. Methods: Patients who underwent endoscopic repair of sagittal craniosynostosis between 2016 and 2019 with available pre- and 1-year postoperative head computed tomography (CT) scans were identified. Age-matched controls with available CT scans were used for comparison. Twenty-one patients with sagittal craniosynostosis who underwent endoscopic repair, 10 preoperative, and 10 postoperative age-matched controls were identified. CT scans were measured with Analyze 12.0 software using soft tissue windows. Head height was defined as the vertical distance from the opisthocranion to the top of the head along a line crossing the tragus. Results: Patients with sagittal craniosynostosis had a shorter head height (mean 6.01 cm) than age-matched controls (mean 6.94 cm, P = .0003), and, after endoscopic repair and helmeting, the head height (mean 8.05 cm) was similar to age matched controls (mean 8.22 cm, P = .515). Conclusions: This head height measurement quantifies the third dimension of abnormal head shape in sagittal craniosynostosis. Additionally, it is adequately corrected in endoscopic repair with helmeting.

Insights into Orbital Symmetry: A Comprehensive Retrospective Study of 372 Computed Tomography Scans.

Background: The operation planning and production of individualized implants with the help of AI-based software after orbital fractures have become increasingly important in recent years. This retrospective study aimed to investigate the healthy orbitae of 372 patients from CT images in the bone and soft tissue windows using the Disior™ Bonelogic™ CMF Orbital software. (version 2.1.28). Methods: We analyzed the variables orbital volume, length, and area as a function of age and gender and compared bone and soft tissue windows. Results: For all variables, the intraclass correlation showed excellent agreement between the bone and soft tissue windows (p < 0.001). All variables showed higher values when calculated based on bone fenestration with, on average, 1 mL more volume, 0.35 mm more length, and 0.71 cm2 more area (p < 0.001). Across all age groups, men displayed higher values than women with, on average, 8.1 mL larger volume, a 4.78 mm longer orbit, and an 8.5 cm2 larger orbital area (p < 0.001). There was also a non-significant trend in all variables and both sexes toward growth with increasing age. Conclusions: These results mean that, due to the symmetry of the orbits in both the bone and soft tissue windows, the healthy orbit can be mirrored for surgical planning in the event of a fracture.

Time and Tissue Windows in Futile Reperfusion after Ischemic Stroke.

Reperfusion strategies such as vascular thrombolysis and thrombectomy are the first-line treatments recommended for acute ischemic stroke. However, only half of these patients achieve functional independence after endovascular reperfusion of large vessel occlusions. Timely restoration of blood flow is crucial, but not all reperfusion results in benefit, a phenomenon termed futile reperfusion. Futile reperfusion occurs when brain tissue has already suffered irreversible damage before reperfusion or when other factors undermine the benefits of restored blood flow. These factors include reperfusion-not rescued injury, reperfusion-induced injury, and the no-reflow phenomenon. The success of reperfusion therapies also hinges on timing and tissue condition after stroke. Defining these time and tissue windows more precisely could refine stroke interventions, potentially expanding effective reperfusion opportunities tailored to individual patients, thereby reducing the incidence of futile reperfusion. This perspective article delves into the complexities of futile reperfusion and the critical roles of time and tissue windows in determining stroke outcomes.

Impacts of futile reperfusion and reperfusion injury in acute ischemic stroke.

Acute ischemic stroke (AIS) remains to be a challenging cerebrovascular disease. The mainstay of AIS management is endovascular reperfusion therapy, including thrombectomy and thrombolysis. However, ineffective (futile) reperfusion (FR) or reperfusion injury (RI) can be seen in a significant number of patients undergoing reperfusion strategy. In this article, we discuss two clinically relevant concepts known as "time window" and "tissue window" that can impact the clinical outcome of reperfusion therapy. We also explore patient risk factors, leading to FR and RI as well as an emerging concept of "no-reflow phenomenon" seen in ineffective reperfusion. These fundamental concepts provide insight into the clinical management of AIS patients and provide references for future research.

Highly sensitive and accurate detection of cholesterol based on a single red upconversion biosensor.

Cholesterol (CHOL) is an important clinical biochemical indicator that plays an important role in the regulation of the fluidity, permeability, and microstructure of cell membranes. Therefore, it is necessary to accurately monitor CHOL levels in biological samples for the early prevention and diagnosis of various diseases. The single-band red upconversion nanoparticle (UCNP) emits light within the optical transmission window of biological tissues, and can penetrate deeper biological tissues and cause less energy loss due to scattering and thus have higher sensitivity and accuracy. Here, using the nontoxic, sensitive, and photochemically stable 3,3',5,5'-tetramethylbenzidine (TMB) as the quenching agent and single red UCNP as the fluorescent donor, a dual-readout colorimetric and fluorescent sensor was developed to detect CHOL. The detection mechanism and feasibility were discussed in detail, and experimental conditions such as Fe2+ concentration, TMB concentration and reaction time were explored. Under optimal conditions, the limits of CHOL detection by colorimetry and fluorescence were 0.85 μM and 0.63 μM. The sensing system was used to measure CHOL in serum samples and the values obtained by these two modes were close, and the spiked recoveries were 97.2-102.2% and 97.1-103.7%, respectively, which holds great potential in clinical diagnosis and health management.

Minimally-invasive lag screw fixation technique for posterior malleolus fractures: A cadaveric study

Anatomical reduction and lag screw fixation of posterior malleolar (PM) ankle fractures typically involves an open posterolateral approach. The aim of this anatomical study was to assess whether a minimally-invasive, percutaneous posterior-to-anterior lag screw fixation technique is safe to perform. Eighteen cadaveric ankle specimens were used. A transverse incision was made at the lateral border of the Tendo Achilles (TA). Windows were made lateral to and through the substance of the TA and simulated reduction and placement of a single lag screw performed. Specimens were then fully dissected to ascertain proximity and damage to anatomical structures. Lag screw fixation was placed appropriately in all ankles. No injury to the neurovascular structures, ankle joint or syndesmotic ligaments was observed. The mean distance from the soft tissue window to sural nerve was 10.0 mm (range 5–16), and 9.5 mm to short saphenous vein (4–14). Whilst the muscle belly of flexor hallucis longus (FHL) was pierced in six specimens, no injuries to the FHL tendon were observed. The mean distance from screw to syndesmosis was 9.3 mm (range 3–15) and 12.7 mm to the ankle joint (7–17). This study demonstrates that posterior percutaneous lag screw fixation is both safe and accurate. Further work is required to evaluate the precision of reduction and the biomechanical stability of this fixation technique. This novel minimally-invasive technique may be beneficial in avoiding the wound complications associated with open posterolateral ankle approaches and also offer a functional advantage due to minimal soft tissue disruption.

Effect of time delay in inter-hospital transfer on outcomes of endovascular treatment of acute ischemic stroke.

Endovascular treatment (EVT) with mechanical thrombectomy is the standard of care for large vessel occlusion (LVO) in acute ischemic stroke (AIS). The most common approach today is to perform EVT in a comprehensive stroke center (CSC) and transfer relevant patients for EVT from a primary stroke center (PSC). Rapid and efficient treatment of LVO is a key factor in achieving a good clinical outcome. We present our retrospective cohort of patients who underwent EVT between 2018 and 2021, including direct admissions and patients transferred from PSC. Primary endpoints were time intervals (door-to-puncture, onset-to-puncture, door-to-door) and favorable outcome (mRS ≤ 2) at 90 days. Secondary outcomes were successful recanalization, mortality rate, and symptomatic intracranial hemorrhage (sICH). Additional analysis was performed for transferred patients not treated with EVT; endpoints were time intervals, favorable outcomes, and reason for exclusion of EVT. Among a total of 405 patients, 272 were admitted directly to our EVT center and 133 were transferred; there was no significant difference between groups in the occluded vascular territory, baseline NIHSS, wake-up strokes, or thrombolysis rate. Directly admitted patients had a shorter door-to-puncture time than transferred patients (190 min vs. 293 min, p < 0.001). The median door-to-door shift time was 204 min. We found no significant difference in functional independence, successful recanalization rates, or sICH rates. The most common reason to exclude transferred patients from EVT was clinical or angiographic improvement (55.6% of patients). Our results show that transferring patients to the EVT center does not affect clinical outcomes, despite the expected delay in EVT. Reassessment of patients upon arrival at the CSC is crucial, and patient selection should be done based on both time and tissue window.

Contrast enhanced computed tomography of small ruminants: Caprine and ovine.

The use of small ruminants, mainly sheep and goats, is increasing in biomedical research. Small ruminants are a desirable animal model due to their human-like anatomy and physiology. However, the large variability between studies and lack of baseline data on these animals creates a barrier to further research. This knowledge gap includes a lack of computed tomography (CT) scans for healthy subjects. Full body, contrast enhanced CT scans of caprine and ovine subjects were acquired for subsequent modeling studies. Scans were acquired from an ovine specimen (male, Khatadin, 30-35 kg) and caprine specimen (female, Nubian 30-35 kg). Scans were acquired with and without contrast. Contrast enhanced scans utilized 1.7 mL/kg of contrast administered at 2 mL/s and scans were acquired 20 seconds, 80 seconds, and 5 minutes post-contrast. Scans were taken at 100 kV and 400 mA. Each scan was reconstructed using a bone window and a soft tissue window. Sixteen full body image data sets are presented (2 specimens by 4 contrast levels by 2 reconstruction windows) and are available for download through the form located at: https://redcap.link/COScanData. Scans showed that the post-contrast timing and scan reconstruction method affected structural visualization. The data are intended for further biomedical research on ruminants related to computational model development, device prototyping, comparative diagnostics, intervention planning, and other forms of translational research.

Exploring Structural-Photophysical Property Relationships in Mitochondria-Targeted Deep-Red/NIR-Emitting Coumarins.

Organic fluorophores operating in the optical window of biological tissues, namely in the deep-red and near-infrared (NIR) region of the electromagnetic spectrum, offer several advantages for fluorescence bioimaging applications owing to the appealing features of long-wavelength light, such as deep tissue penetration, lack of toxicity, low scattering, and reduced interference with cellular autofluorescence. Among these, COUPY dyes based on non-conventional coumarin scaffolds display suitable photophysical properties and efficient cellular uptake, with a tendency to accumulate primarily in mitochondria, which renders them suitable probes for bioimaging purposes. In this study, we have explored how the photophysical properties and subcellular localization of COUPY fluorophores can be modulated through the modification of the coumarin backbone. While the introduction of a strong electron-withdrawing group, such as the trifluoromethyl group, at position 4 resulted in an exceptional photostability and a remarkable redshift in the absorption and emission maxima when combined with a julolidine ring replacing the N,N-dialkylaminobenzene moiety, the incorporation of a cyano group at position 3 dramatically reduced the brightness of the resulting fluorophore. Interestingly, confocal microscopy studies in living HeLa cells revealed that the 1,1,7,7-tetramethyl julolidine-containing derivatives accumulated in the mitochondria with much higher specificity. Overall, our results provide valuable insights for the design and optimization of new COUPY dyes operating in the deep-red/NIR region.

Merocyanines form bacteriorhodopsins with strongly bathochromic absorption maxima

There is a need to shift the absorbance of biomolecules to the optical transparency window of tissue for applications in optogenetics and photo-pharmacology. There are a few strategies to achieve the so-called red shift of the absorption maxima. Herein, a series of 11 merocyanine dyes were synthesized and employed as chromophores in place of retinal in bacteriorhodopsin (bR) to achieve a bathochromic shift of the absorption maxima relative to bR’s λmaxa\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$${\\lambda }_{\\mathrm{max}}^{a}$$\\end{document} of 568 nm. Assembly with the apoprotein bacterioopsin (bO) led to stable, covalently bound chromoproteins with strongly bathochromic absorbance bands, except for three compounds. Maximal red shifts were observed for molecules 9, 2, and 8 in bR where the λmaxa\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$${\\lambda }_{\\mathrm{max}}^{a}$$\\end{document} was 766, 755, and 736 nm, respectively. While these three merocyanines have different end groups, they share a similar structural feature, namely, a methyl group which is located at the retinal equivalent position 13 of the polyene chain. The absorption and fluorescence data are also presented for the retinal derivatives in their aldehyde, Schiff base (SB), and protonated SB (PSB) forms in solution. According to their hemicyanine character, the PSBs and their analogue bRs exhibited fluorescence quantum yields (Φf) several orders of magnitude greater than native bR (Φf 0.02 to 0.18 versus 1.5 × 10–5 in bR) while also exhibiting much smaller Stokes shifts than bR (400 to 1000 cm−1 versus 4030 cm−1 in bR). The experimental results are complemented by quantum chemical calculations where excellent agreement between the experimental λmaxa\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$${\\lambda }_{\\mathrm{max}}^{a}$$\\end{document} and the calculated λmaxa\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$${\\lambda }_{\\mathrm{max}}^{a}$$\\end{document} was achieved with the second-order algebraic-diagrammatic construction [ADC(2)] method. In addition, quantum mechanics/molecular mechanics (QM/MM) calculations were employed to shed light on the origin of the bathochromic shift of merocyanine 2 in bR compared with native bR.Graphical abstract