Visualization of intradermal blood vessel structures by dual-wavelength photoacoustic microscopy and characterization of three-dimensional construction of livedo-racemosa in cutaneous polyarteritis nodosa

BACKGROUND

Photoacoustic microscopy is expected to have clinical applications as a noninvasive and three-dimensional (3D) method of observing intradermal structures.

OBJECTIVE

Investigate the applicability of a photoacoustic microscope equipped with two types of pulsed lasers that can simultaneously recognize hemoglobin and melanin.

METHODS

16 skin lesions including erythema, pigmented lesions, vitiligo and purpura, were analyzed to visualize 3D structure of melanin granule distribution and dermal blood vessels. 13 cases of livedo racemosa in cutaneous polyarteritis nodosa (cPN) were further analyzed to visualize the 3D structure of dermal blood vessels in detail. Vascular structure was also analyzed in the biopsy specimens obtained from tender indurated erythema of cPN by CD34 immunostaining.

RESULTS

Hemoglobin-recognition signal clearly visualized the 3D structure of dermal blood vessels and melanin-recognition signal was consistently reduced in vitiligo. In livedo racemosa, the hemoglobin-recognition signal revealed a relatively thick and large reticular structure in the deeper layers that became denser and finer toward the upper layers. The numerical analysis revealed that the number of dermal blood vessels was 1.29-fold higher (p<0.05) in the deeper region of the lesion than that of normal skin. The CD34 immunohistochemical analysis in tender indurated erythema revealed an increased number of dermal vessels compared with normal skin in 88.9% (8/9) of the cases, suggesting that vascular network remodeling had occurred in cPN.

CONCLUSION

The photoacoustic system has an advantage in noninvasively detecting dermal blood vessel structures that are difficult to recognize by two-dimensional histopathology specimen examination and is worth evaluating in various skin diseases.

Preoperative photoacoustic versus indocyanine green lymphography in lymphaticovenular anastomosis outcomes for lower extremity lymphedema: A pilot study

BACKGROUND

Identification of the proper lymphatics is important for successful lymphaticovenular anastomosis (LVA) for lymphedema; however, visualization of lymphatic vessels is challenging. Photoacoustic lymphangiography (PAL) can help visualize lymphatics more clearly than other modalities. Therefore, we investigated the usefulness of PAL and determined whether the clear and three-dimensional image of PAL affects LVA outcomes.

METHODS

We recruited 22 female patients with lower extremity lymphedema. The operative time, number of incisions, number of anastomoses, lymphatic vessel detection rate (number of functional lymphatics identified during the operation/number of incisions), and limb volume changes preoperatively and 3 months postoperatively were compared retrospectively. The patients were divided according to whether PAL was performed or not, and results were compared between those undergoing PAL (PAL group; n = 10) and those who did not (near-infrared fluorescence [NIRF] group, n = 12).

RESULTS

The mean age of the patients was 55.9 ± 15.1 years in the PAL group and 50.7 ± 14.9 years in the NIRF group. One patient in the PAL group and three in the NIRF group had primary lymphedema. Eighteen patients (PAL group, nine; and NIRF group, nine) had secondary lymphedema. Based on preoperative evaluation using the International Society of Lymphology (ISL) classification, eight patients were determined to be in stage 2 and two patients in late stage 2 in the PAL group. In contrast, in the NIRF group, one patient was determined to be in stage 0, three patients each in stage 1 and stage 2, and five patients in late stage 2. Lymphatic vessel detection rates were 93% (42 LVAs and 45 incisions) and 83% (50 LVAs and 60 incisions) in the groups with and without PAL, respectively (p = 0.42). Limb volume change was evaluated in five limbs of four patients and in seven limbs of five patients in the PAL and NIRF groups as 336.6 ± 203.6 mL (5.90% ± 3.27%) and 52.9 ± 260.7 mL (0.71% ± 4.27%), respectively. The PAL group showed a significant volume reduction. (p = .038).

CONCLUSIONS

Detection of functional lymphatic vessels on PAL is useful for treating LVA.

Efficacy of Cranial Orthosis for Plagiocephaly Based on 2D and 3D Evaluation

Background  With the advent of cranial orthoses as therapeutic medical devices for the treatment of severe positional head deformities in Japan, an increasing number of patients are being treated with them. However, assessing the effectiveness of a treatment is often difficult due to the use of different metrics. This study aimed to evaluate the effectiveness of cranial orthoses for deformational plagiocephaly using two- (2D) and three-dimensional (3D) evaluation metrics. Methods  We conducted a retrospective study of infant patients with deformational plagiocephaly who underwent cranial orthosis treatment. We evaluated the severity of deformational plagiocephaly using cranial asymmetry (CA) and the cranial vault asymmetry index (CVAI) as 2D metrics, and anterior and posterior symmetry ratios as 3D metrics. The patients were divided into 24 subgroups based on the initial severity of each outcome and their age at the start of treatment. We analyzed the changes in outcomes and correlations within improvements across the age and severity categories. Results  Overall, 1,038 infants were included in this study. The mean CA, CVAI, and anterior and posterior symmetry ratios improved significantly after cranial orthosis treatment. The improvement in each score was greater in patients with more severe initial deformities and in those who underwent treatment at a younger age. Conclusion  Cranial orthosis treatment was effective in correcting deformational plagiocephaly in infants, as demonstrated by improvements in both 2D and 3D metrics. Patients with more severe initial deformities and those who underwent treatment at a younger age showed greater improvement.

An analysis on the effect of body tissues and surgical tools on workflow recognition in first person surgical videos

PURPOSE

Analysis of operative fields is expected to aid in estimating procedural workflow and evaluating surgeons' procedural skills by considering the temporal transitions during the progression of the surgery. This study aims to propose an automatic recognition system for the procedural workflow by employing machine learning techniques to identify and distinguish elements in the operative field, including body tissues such as fat, muscle, and dermis, along with surgical tools.

METHODS

We conducted annotations on approximately 908 first-person-view images of breast surgery to facilitate segmentation. The annotated images were used to train a pixel-level classifier based on Mask R-CNN. To assess the impact on procedural workflow recognition, we annotated an additional 43,007 images. The network, structured on the Transformer architecture, was then trained with surgical images incorporating masks for body tissues and surgical tools.

RESULTS

The instance segmentation of each body tissue in the segmentation phase provided insights into the trend of area transitions for each tissue. Simultaneously, the spatial features of the surgical tools were effectively captured. In regard to the accuracy of procedural workflow recognition, accounting for body tissues led to an average improvement of 3 % over the baseline. Furthermore, the inclusion of surgical tools yielded an additional increase in accuracy by 4 % compared to the baseline.

CONCLUSION

In this study, we revealed the contribution of the temporal transition of the body tissues and surgical tools spatial features to recognize procedural workflow in first-person-view surgical videos. Body tissues, especially in open surgery, can be a crucial element. This study suggests that further improvements can be achieved by accurately identifying surgical tools specific to each procedural workflow step.

Reliability-Aware Restoration Framework for 4D Spectral Photoacoustic Data

Spectral photoacoustic imaging (PAI) is a new technology that is able to provide 3D geometric structure associated with 1D wavelength-dependent absorption information of the interior of a target in a non-invasive manner. It has potentially broad applications in clinical and medical diagnosis. Unfortunately, the usability of spectral PAI is severely affected by a time-consuming data scanning process and complex noise. Therefore in this study, we propose a reliability-aware restoration framework to recover clean 4D data from incomplete and noisy observations. To the best of our knowledge, this is the first attempt for the 4D spectral PA data restoration problem that solves data completion and denoising simultaneously. We first present a sequence of analyses, including modeling of data reliability in the depth and spectral domains, developing an adaptive correlation graph, and analyzing local patch orientation. On the basis of these analyses, we explore global sparsity and local self-similarity for restoration. We demonstrated the effectiveness of our proposed approach through experiments on real data captured from patients, where our approach outperformed the state-of-the-art methods in both objective evaluation and subjective assessment.

A technique for decreasing reflection during cadaveric photography

To create anatomical educational materials that can be viewed in three dimensions using stereo photographs and photogrammetry, multiple photographs must be taken from different directions. In this process, shadows and reflections from different positions in each photograph are undesirable for creating three-dimensional (3D) anatomy educational materials. Although a ring flash eliminates shadows, allowing light to enter from all directions, reflections cannot be eliminated. In particular, Thiel-embalmed cadavers, which are widely used in clinical anatomy, are highly wet and exhibit strong specular highlights. In this study, a straight polarization filter was attached to a handheld camera lens and ring flash, and shooting was performed using cross-polarization photography. Consequently, even in Thiel-embalmed cadavers, the details lost due to the effects of reflections and shadows can be recovered, and good results can be obtained when taking stereo photos or creating a 3D model using photogrammetry.

A Novel Dissection Method of the Internal Mammary (Thoracic) Artery: Anastomotic Vessel of the DIEP Flap

Deep inferior epigastric perforator flaps are commonly used for breast reconstruction using autologous tissue. For such free flaps, the internal mammary artery provides stable blood flow as the recipient for anastomosis. We report a novel dissection method of the internal mammary artery. First, the perichondrium and costal cartilage of the sternocostal joint are dissected with electrocautery. Then, the incision on the perichondrium is extended along the cephalic and caudal ends. Next, this C-shaped superficial layer of perichondrium is elevated from the cartilage. The cartilage is incompletely fractured with electrocautery, with the deep layer of perichondrium intact. Then, the cartilage is completely fractured by leverage and removed. The remaining deep layer of perichondrium is incised at the costochondral junction and shifted aside, revealing the internal mammary artery. The preserved perichondrium creates a rabbet joint to protect the anastomosed artery. This method not only enables a more reliable, safer dissection of the internal mammary artery, but also allows reusage of the perichondrium as underlayment in the setting of anastomosis, and coverage for the incised rib edge, protecting the anastomosed vessels.

Corrigendum: Single-cell RNA-seq analysis reveals cellular functional heterogeneity in dermis between fibrotic and regenerative wound healing fates

[This corrects the article DOI: 10.3389/fimmu.2022.875407.].

Measurement of lymphatic vessel depth using photoacoustic imaging

OBJECTIVES

Information regarding the depth of lymphatic vessel is important for lymphatic surgeons because rapid identification of functional lymphatic vessels and veins is necessary to perform good lymphaticovenular anastomosis, which is a surgical procedure for lymphedema cases. Photoacoustic lymphangiography (PAL) may be useful for such identification because it allows the assessment of the depth of lymphatic vessels. Thus, we aimed to measure the lymphatic vessel depth using images obtained by PAL.

METHODS

This study included healthy individuals and patients with lymphedema. In all participants, indocyanine green dissolved in dextrose was injected subcutaneously into the first and fourth webs of the foot and the lateral malleolus, and PAL was performed on the medial side of the lower leg. The lymphatic vessel depth was measured from the ankle joint, 10 cm above the medial malleolus, and 20 cm above the medial malleolus on PAL in the cross-sectional view and was compared between the participant groups.

RESULTS

The healthy group (mean age, 43.3 ± 12.9 years) included 21 limbs of 4 male and 16 female healthy individuals (bilateral limbs of 1 patient were considered). The lymphedema group (mean age, 62.0 ± 11.7 years) included 17 limbs of 3 male and 14 female patients with lymphedema. The average lymphatic vessel depths from the ankle joint, 10 cm above the medial malleolus, and 20 cm above the medial malleolus were 2.6, 4.7, and 5.6 mm in the healthy group and 3.6, 7.3, and 7.4 mm in the lymphedema group, respectively. Lymphatic vessels were significantly deeper in the lymphedema group than in the healthy group at all measurement locations.

CONCLUSIONS

Using PAL, we determined the lymphatic vessel depth in living bodies. By searching for the lymphatic vessels based on our findings, even surgeons who are relatively inexperienced with lymphatic surgery may be able to identify functional lymphatic vessels more efficiently.

Photoacoustic lymphangiography is a possible alternative for lymphedema staging

OBJECTIVE

Photoacoustic imaging is a new technique that uses the photoacoustic effect. In photoacoustic lymphangiography (PAL), images of the lymphatic vessels can be visualized using light-absorbing contrast agents. In the present study, we investigated the efficacy of PAL for lymphedema staging.

METHODS

We performed PAL of the lower extremities and examined the clinical implications of using PAL for staging lymphedema by comparing the PAL images with those obtained using lymphoscintigraphy. Of 47 patients with lymphedema who had been outpatients or hospitalized at our institution between May 2018 and September 2020 and had undergone PAL, 15 with 18 limbs who had also undergone lymphoscintigraphy were included in the present study. The lymphoscintigraphy findings were classified using the Maegawa classification. We also investigated whether PAL could clearly visualize the lymphatic vessels and concisely reflect the disease state by counting the number of lymphatic vessels observed using PAL.

RESULTS

The PAL findings were categorized into three groups: collecting lymphatic vessels, dermal backflow (DBF), and no lymphatic vessels. The collecting lymphatic vessels group corresponded to types 2 and 3 in the Maegawa classification; DBF corresponded to types 3 and 4, and the no lymphatic vessels group corresponded to type 4. The number of lymphatic vessels visualized using PAL was similar to that with lymphoscintigraphy. As the disease progressed, the number of lymphatic vessels observed decreased, increased DBF was detected, and, eventually, the lymphatic vessels were not visible, corresponding to the general changes observed via lymphoscintigraphy with stage progression.

CONCLUSIONS

The findings from PAL and lymphoscintigraphy tended to correspond, suggesting that PAL could be useful for lymphedema staging.

Mesenchymal Stem Cells Promote IL-6 Secretion and Suppress the Gene Expression of Proinflammatory Cytokines in Contractile C2C12 Myotubes

Sarcopenia is not only a major cause of disability but also a risk factor for obesity and diabetes in elderly persons. Exercise is an effective method for improving the sarcopenic condition by inducing the secretion of interleukin (IL)-6, which has the capacities to both promote muscle hypertrophy and regulate lipid metabolism and glucose homeostasis, by skeletal muscle. We previously showed that mesenchymal stem cells (MSCs) promote IL-6 secretion by lipopolysaccharide-stimulated C2C12 mouse skeletal muscle myotubes via paracrine mechanisms. Therefore, in this study, we investigated the effect of paracrine actions of MSCs on IL-6 and proinflammatory cytokine expression in contractile C2C12 myotubes by applying electrical stimulation. IL-6 secretion by C2C12 myotubes was increased by electrical stimulation, and a more significant increase in IL-6 secretion was observed in electrically stimulated C2C12 myotubes cultured in conditioned medium from MSCs. The activation of nuclear factor-κB in C2C12 myotubes was also promoted by the combination of conditioned medium from MSCs and electrical stimulation. Moreover, the increases in tumor necrosis factor-α and IL-1β mRNA expression in C2C12 myotubes induced by electrical stimulation were suppressed by culture in conditioned medium from MSCs. The present findings suggest that MSCs transplantation or injection of their extracellular vesicles improve the therapeutic effect of exercise against sarcopenia without exacerbating inflammation.

Single-Cell RNA-seq Analysis Reveals Cellular Functional Heterogeneity in Dermis Between Fibrotic and Regenerative Wound Healing Fates

Background

Fibrotic scars are common in both human and mouse skin wounds. However, wound-induced hair neogenesis in the murine wounding models often results in regenerative repair response. Herein, we aimed to uncover cellular functional heterogeneity in dermis between fibrotic and regenerative wound healing fates.

Methods

The expression matrix of single-cell RNA sequencing (scRNA-seq) data of fibrotic and regenerative wound dermal cells was filtered, normalized, and scaled; underwent principal components analysis; and further analyzed by Uniform Manifold Approximation and Projection (UMAP) for dimension reduction with the Seurat package. Cell types were annotated, and cell-cell communications were analyzed. The core cell population myofibroblast was identified and the biological functions of ligand and receptor genes between myofibroblast and macrophage were evaluated. Specific genes between fibrotic and regenerative myofibroblast and macrophage were identified. Temporal dynamics of myofibroblast and macrophage were reconstructed with the Monocle tool.

Results

Across dermal cells, there were six cell types, namely, EN1-negative myofibroblasts, EN1-positive myofibroblasts, hematopoietic cells, macrophages, pericytes, and endothelial cells. Ligand and receptor genes between myofibroblasts and macrophages mainly modulated cell proliferation and migration, tube development, and the TGF-β pathway. Specific genes that were differentially expressed in fibrotic compared to regenerative myofibroblasts or macrophages were separately identified. Specific genes between fibrotic and regenerative myofibroblasts were involved in the mRNA metabolic process and organelle organization. Specific genes between fibrotic and regenerative macrophages participated in regulating immunity and phagocytosis. We then observed the underlying evolution of myofibroblasts or macrophages.

Conclusion

Collectively, our findings reveal that myofibroblasts and macrophages may alter the skin wound healing fate through modulating critical signaling pathways.

Surgical Applications of Lymphatic Vessel Visualization Using Photoacoustic Imaging and Augmented Reality

Lymphaticovenular anastomosis (LVA) is a widely performed surgical procedure for the treatment of lymphedema. For good LVA outcomes, identifying lymphatic vessels and venules is crucial. Photoacoustic lymphangiography (PAL) is a new technology for visualizing lymphatic vessels. It can depict lymphatic vessels at high resolution; therefore, this study focused on how to apply PAL for lymphatic surgery. To visualize lymphatic vessels, indocyanine green was injected as a color agent. PAI-05 was used as the photoacoustic imaging device. Lymphatic vessels and veins were visualized at 797- and 835-nm wavelengths. First, it was confirmed whether the branching of the vasculature as depicted by the PAL was consistent with the actual branching of the vasculature as confirmed intraoperatively. Second, to use PAL images for surgical planning, preoperative photoacoustic images were superimposed onto the patient limb through augmented reality (AR) glasses (MOVERIO Smart Glass BT-30E). Lymphatics and venule markings drawn using AR glasses were consistent with the actual intraoperative images obtained during LVA. To anastomose multiple lymphatic vessels, a site with abundant venous branching was selected as the incision site; and selecting the incision site became easier. The anatomical morphology obtained by PAL matched the surgical field. AR-based marking could be very useful in future LVA.

Application of Photoacoustic Imaging for Lymphedema Treatment

Background  Lymphatic vessels are difficult to identify using existing modalities as because of their small diameter and the transparency of the lymph fluid flowing through them.

Methods  Here, we introduce photoacoustic lymphangiography (PAL), a new modality widely used for lymphedema treatment, to observe limb lymphatic vessels. The photoacoustic imaging system used in this study can simultaneously visualize lymphatic vessels and veins with a high resolution (0.2 mm) and can also observe their three-dimensional relationship with each other.

Results  High-resolution images of the lymphatic vessels, detailed structure of the dermal back flow, and the three-dimensional positional relationship between the lymphatic vessels and veins were observed by PAL.

Conclusion  The clear image provided by PAL could have a major application in pre- and postoperative use during lymphaticovenular anastomosis for lymphedema treatment.

Unsupervised Body Hair Detection by Positive-Unlabeled Learning in Photoacoustic Image

Photoacoustic (PA) imaging is a new imaging technology that can non-invasively visualize blood vessels and body hair in 3D. It is useful in cosmetic surgery for detecting body hair and computing metrics such as the number and thicknesses of hairs. Previous supervised body hair detection methods often do not work if the imaging conditions change from training data. We propose an unsupervised hair detection method. Hair samples were automatically extracted from unlabeled samples using prior knowledge about spatial structure. If hair (positive) samples and unlabeled samples are obtained, Positive Unlabeled (PU) learning becomes possible. PU methods can learn a binary classifier from positive samples and unlabeled samples. The advantage of the proposed method is that it can estimate an appropriate decision boundary in accordance with the distribution of the test data. Experimental results using real PA data demonstrate that the proposed approach effectively detects body hairs.

Photoacoustic lymphangiography exhibits advantages over near-infrared fluorescence lymphangiography as a diagnostic tool in patients with lymphedema

OBJECTIVE

Photoacoustic imaging (PAI) is a new technique that can evaluate the vascular system using photoacoustic effects. The present study compared the ability of the new photoacoustic lymphangiography (PAL) method and more standard near-infrared fluorescence (NIRF) to image the lymphatic system in patients with secondary lymphedema following gynecological cancer surgery.

METHODS

Patients with secondary lymphedema in the lower extremities following gynecologic cancer surgery, who were assessed using PAL between May 2018 and January 2019 were recruited. NIRF was performed first using 5.0 mg/mL of indocyanine green injected using a 0.2-cc 30-gauge needle. Correlations between NIRF and PAL findings on patient images were subsequently examined.

RESULTS

Seventeen patients with secondary lymphedema were enrolled. The mean age of the patients was 61 ± 11 years. The imaging sites were the medial lower leg in 15 patients, the posterior lower leg in nine patients, the lateral lower leg in seven patients, the medial knee in four patients, and other areas in three patients. A total of 38 pictures were obtained. Five distinct lymphatic patterns were observed over the entire sample using PAL: straight, winding, spiderweb, nebulous, and black-out pattern Eighteen of the 24 limbs (75%) that exhibited a linear pattern in NIRF exhibited a straight pattern in PAL, and 19 of the 20 limbs (95%) that exhibited a splash pattern in NIRF exhibited a winding or spider web pattern in PAL. Eight limbs exhibiting diffuse patterns without linear or splash patterns with NIRF were all nebulous or black-out patterns in PAL. This suggests that more severe lymphatic degeneration was associated with poorer visualization in PAL.

CONCLUSIONS

NIRF plays an important role in lymphedema treatment. In the present study, various PAL patterns were compared with those observed using NIRF. PAL provided clearer images including transectional views, which were not available using NIRF, and may promote further understanding of the changes in the lymphatic structure and function in patients with secondary lymphedema.

Deep learning in diabetic foot ulcers detection: A comprehensive evaluation

There has been a substantial amount of research involving computer methods and technology for the detection and recognition of diabetic foot ulcers (DFUs), but there is a lack of systematic comparisons of state-of-the-art deep learning object detection frameworks applied to this problem. DFUC2020 provided participants with a comprehensive dataset consisting of 2,000 images for training and 2,000 images for testing. This paper summarizes the results of DFUC2020 by comparing the deep learning-based algorithms proposed by the winning teams: Faster R-CNN, three variants of Faster R-CNN and an ensemble method; YOLOv3; YOLOv5; EfficientDet; and a new Cascade Attention Network. For each deep learning method, we provide a detailed description of model architecture, parameter settings for training and additional stages including pre-processing, data augmentation and post-processing. We provide a comprehensive evaluation for each method. All the methods required a data augmentation stage to increase the number of images available for training and a post-processing stage to remove false positives. The best performance was obtained from Deformable Convolution, a variant of Faster R-CNN, with a mean average precision (mAP) of 0.6940 and an F1-Score of 0.7434. Finally, we demonstrate that the ensemble method based on different deep learning methods can enhance the F1-Score but not the mAP.

Use of photoacoustic imaging to determine the effects of aging on lower extremity lymphatic vessel function

OBJECTIVE

Aging is one of the causes of primary lymphedema. However, the effects of aging on the lymphatic system are still not completely understood. We investigated the effects of aging on the lymphatic vessels in the lower extremities of healthy volunteers using photoacoustic imaging.

METHODS

Healthy volunteers who underwent photoacoustic lymphangiography between March 2018 and January 2019 were enrolled. To visualize lymphatics, indocyanine green (ICG, 5.0 mg/mL) was injected subcutaneously into the first and fourth web spaces of the foot and under the lateral malleolus. Subsequently, near-infrared fluorescence lymphography was performed to confirm good ICG flow, and photoacoustic lymphangiography was performed on the medial side of the lower leg. Neodymium-doped yttrium aluminum garnet laser irradiation at 797 and 835 nm, the optimal wavelengths for visualizing ICG and blood, was applied. The number of lymphatic vessels shown at areas 10 cm (L10) and 20 cm (L20) cranially from the internal malleolus was counted.

RESULTS

Nineteen healthy volunteers (4 males and 15 females) were enrolled in the study. Their mean age was 42.9 ± 12.8 years. One volunteer was bilaterally imaged; 15 left lower limbs and 5 right lower limbs were imaged. The number of lymphatic vessels visualized increased with age. There were strong positive correlations between age and L10 (R = 0.729, P < .001) and between age and L20 (R = 0.570, P = .009).

CONCLUSIONS

Photoacoustic imaging indicates that the number of lymphatic vessels increases with age. Lymphatic stasis resulted in visualization of not only normal drainage pathways but also nonfunctional lymphatic pathways.

Cell and tissue system capable of automated culture, stimulation, and monitor with the aim of feedback control of organs-on-a-chip

This paper presents progress in the automation of cell and tissue systems and attempts toward the in situ feedback control of organs-on-a-chip. Our study aims to achieve feedback control of a cell and tissue system by a personal computer (PC), whereas most studies on organs-on-a-chip focus on the automation of status monitoring. The implemented system is composed of subsystems including automated culture, stimulation, and monitoring. The monitoring function provides imaging as well as sampling and dispensing in combination with an external analyzer. Individual subsystems can be combined accordingly. First, monitoring of skeletal muscle (SM) and adipose tissues using this system was demonstrated. The highlight of this paper is the application of the system to the feedback control of the lipid droplet (LD) size, where biochemical stimulation using insulin and adrenaline is controlled by a PC according to the obtained LD imaging data. In this study, the system demonstrated its function of maintaining the desired size of LDs. Our results expand the possibility of PC-controllable cell and tissue systems by addressing the challenge of feedback control of organs-on-a-chip. The PC-controllable cell and tissue systems will contribute to living systems-on-a-chip based on homeostasis phenomena involving interactions between organs or tissues.

Hand Motion-Aware Surgical Tool Localization and Classification from an Egocentric Camera

Detecting surgical tools is an essential task for the analysis and evaluation of surgical videos. However, in open surgery such as plastic surgery, it is difficult to detect them because there are surgical tools with similar shapes, such as scissors and needle holders. Unlike endoscopic surgery, the tips of the tools are often hidden in the operating field and are not captured clearly due to low camera resolution, whereas the movements of the tools and hands can be captured. As a result that the different uses of each tool require different hand movements, it is possible to use hand movement data to classify the two types of tools. We combined three modules for localization, selection, and classification, for the detection of the two tools. In the localization module, we employed the Faster R-CNN to detect surgical tools and target hands, and in the classification module, we extracted hand movement information by combining ResNet-18 and LSTM to classify two tools. We created a dataset in which seven different types of open surgery were recorded, and we provided the annotation of surgical tool detection. Our experiments show that our approach successfully detected the two different tools and outperformed the two baseline methods.

Subcutaneous Lymphatic Vessels in the Lower Extremities: Comparison between Photoacoustic Lymphangiography and Near-Infrared Fluorescence Lymphangiography

Background Detailed visualization of the lymphatic vessels would greatly assist in the diagnosis and monitoring of lymphatic diseases and aid in preoperative planning of lymphedema surgery and postoperative evaluation. Purpose To evaluate the usefulness of photoacoustic imaging (PAI) for obtaining three-dimensional images of both lymphatic vessels and surrounding venules. Materials and Methods In this prospective study, the authors recruited healthy participants from March 2018 to January 2019 and imaged lymphatic vessels in the lower limbs. Indocyanine green (5.0 mg/mL) was injected into the subcutaneous tissue of the first and fourth web spaces of the toes and below the lateral malleolus. After confirmation of the lymphatic flow with near-infrared fluorescence (NIRF) imaging as the reference standard, PAI was performed over a field of view of 270 × 180 mm. Subsequently, the number of enhancing lymphatic vessels was counted in both proximal and distal areas of the calf and compared between PAI and NIRF. Results Images of the lower limbs were obtained with PAI and NIRF in 15 participants (three men, 12 women; average age, 42 years ± 12 [standard deviation]). All participants exhibited a linear pattern on NIRF images, which is generally considered a reflection of good lymphatic function. A greater number of lymphatic vessels were observed with PAI than with NIRF in both the distal (mean: 3.6 vessels ± 1.2 vs 2.0 vessels ± 1.1, respectively; P < .05) and proximal (mean: 6.5 vessels ± 2.6 vs 2.6 vessels ± 1.6; P < .05) regions of the calf. Conclusion Compared with near-infrared fluorescence imaging, photoacoustic imaging provided a detailed, three-dimensional representation of the lymphatic vessels and facilitated an increased understanding of their relationship with the surrounding venules. © RSNA, 2020 Online supplemental material is available for this article. See also the editorial by Lillis and Krishnamurthy in this issue.

Photoacoustic lymphangiography

BACKGROUND AND OBJECTIVES

Photoacoustic lymphangiography, which is based on photoacoustic technology, is an optical imaging that visualizes the distribution of light absorbing tissue components like hemoglobin or melanin, as well as optical absorption contrast imaging agents like indocyanine green (ICG) in the lymphatic channels, with high spatial resolution. In this report, we introduce the three-dimensional (3D) images of human lymphatic vessels obtained with photoacoustic lymphangiography.

METHODS

We used the 3D photoacoustic visualization system (PAI-05). Some healthy subjects and lymphedema patients were recruited. To image the lymphatic structures of the limbs ICG was administered subcutaneously as in fluorescence lymphangiography. Photoacoustic images were acquired by irradiating the tissue using a laser at wavelengths of near-infrared region. On the same occasion, fluorescence images were also recorded.

RESULTS

The lymphatic vessels up to the diameter of 0.2 mm could be observed three-dimensionally with the venules around them. In the patient-group, dermal backflow patterns were often observed as dense interconnecting 3D structures of lymphatic vessels. Collecting vessels passing below the dermis were also observed, which were not observed by fluorescence lymphography.

CONCLUSIONS

Photoacoustic lymphangiography provided the detailed observation of each lymphatic vessel, leading to deeper understanding of 3D structures and physiological state of the vessel.

Detection of Francisella tularensis and analysis of bacterial growth in ticks in Japan

Francisella tularensis is distributed in the Northern hemisphere and it is the bacterial agent responsible for tularaemia, a zoonotic disease. We collected 4 527 samples of DNA from ticks in Japan, which were then analysed by real-time PCR and nested PCR. Francisella DNA was detected by real-time PCR in 2·15% (45/2 093) of Ixodes ovatus, 0·66% (14/2 107) of I. persulcatus, 8·22% (6/73) of I. monospinosus and 0·72% (1/138) of Haemaphysalis flava specimens. Finally, Francisella DNA was detected by nested PCR in 42 and five samples I. ovatus and I. persulcatus, respectively, which were positive according to real-time PCR. Phylogenetic analysis showed that the sequence from I. ovatus and I. persulcatus were clustered with F. tularensis type B strains distributed in Eurasia. Microinjected live F. tularensis persisted in ticks, whereas heat-killed F. tularensis decreased. Microinjected F. tularensis hlyD mutant decreased in ticks significantly compared to parent strain, thereby suggesting that HlyD in F. tularensis contributes to the adaptation or survive of bacterial infection in ticks.

SIGNIFICANCE AND IMPACTS OF THE STUDY

Francisella tularensis has been detected in ticks, suggesting that it is a tick-borne pathogen. However, F. tularensis has not been detected in ticks in Japan since 1991. In this study, we performed a large-scale analysis of DNA isolated from ticks in Japan and detected F. tularensis by real-time polymerase chain reaction (PCR) and nested PCR. We found that F. tularensis could survive in ticks based on an experimental tick-infection model. We also identified a bacterial factor that contributes to survival in ticks. Our results suggest that ticks are candidate vectors that mediate F. tularensis infection in Japan.

Inhibition of cardiac delayed rectifier K+ currents by an antisense oligodeoxynucleotide against IsK (minK) and over-expression of IsK mutant D77N in neonatal mouse hearts

The IsK (minK or KCNE1) protein is known to co-assemble with the KvLQT1 (KCNQ1) protein to form a channel underlying the slowly activating delayed rectifier K+ current (IKs). Controversy remains as to whether the IsK protein assembles with ERG (the ether-a-go-go-related gene) products to form or modulate the channel-underlying the rapidly activating delayed rectifier K+ current (IKr). We investigated the effects of antisense oligodeoxynucleotides (AS-ODN) against IsK and its mutant D77N [which underlies a form of long QT syndrome (LQT5) in humans] on the delayed rectifier K+ current (IK) of neonatal mouse ventricular myocytes in primary culture. Patch-clamp experiments on these cells showed that IK consists of IKs and IKr. IK was not recorded from ventricular cells transfected with AS-ODN, while it was recorded from cells transfected with the corresponding sense oligodeoxynucleotides (S-ODN). IK was not recorded from cells transfected with the D77N mutant, and the action potential duration was much longer than in cells transfected with wild-type IsK. Furthermore, HERG could not induce currents in COS-1 cells co-expressed with the D77N mutant and HERG (the human form of ERG). These results indicate that the IsK protein associates with both KvLQT1 and ERG products to modulate IKr and IKs in cardiac myocytes.

Mechanisms of CSF secretion by the choroid plexus

The epithelial cells of the choroid plexus secrete cerebrospinal fluid (CSF), by a process that involves the movement of Na(+), Cl(-) and HCO(3)(-) from the blood to the ventricles of the brain. This creates the osmotic gradient, which drives the secretion of H(2)O. The unidirectional movement of the ions is achieved due to the polarity of the epithelium, i.e., the ion transport proteins in the blood-facing (basolateral) are different to those in the ventricular (apical) membranes. Saito and Wright (1983) proposed a model for secretion by the amphibian choroid plexus, in which secretion was dependent on activity of HCO(3)(-) channels in the apical membrane. The patch clamp method has now been used to study the ion channels expressed in rat choroid plexus. Two potassium channels have been observed that have a role in maintaining the membrane potential of the epithelial cell, and in regulating the transport of K(+) across the epithelium. An inward-rectifying anion channel has also been identified, which is closely related to ClC-2 channels, and has a significant HCO(3)(-) permeability. This channel is expressed in the apical membrane of the epithelium where it may play an important role in CSF secretion. A model of CSF secretion by the mammalian choroid plexus is proposed that accommodates these channels and other data on the expression of transport proteins in the choroid plexus.

Properties of the inward-rectifying Cl- channel in rat choroid plexus: regulation by intracellular messengers and inhibition by divalent cations

The properties of the inward-rectifying Cl- conductance in rat choroid plexus epithelial cells were investigated to allow comparisons to be made with ClC-2. All experiments were performed using the whole-cell configuration of the patch-clamp method. The conductance was transiently activated using an electrode solution which contained 375 nM catalytic subunit of protein kinase A (PKA). PKA failed to activate the conductance, however, when cells were pre-incubated with phorbol esters, which activate protein kinase C [1 microM phorbol 12-myristate 13-acetate (PMA) and 1 microM phorbol 12,13-dibutyrate (PDBu)]. Sustained activation of the conductance by PKA was observed in Ca2+-free conditions (5 mM BAPTA in the electrode solution), or when 100 nM calphostin C, a PKC inhibitor, was added to the electrode solution. The inward-rectifying Cl- conductance in choroid plexus is therefore similar to ClC-2 in that it is inhibited by PKC. The inward-rectifying conductance was blocked when Cd2+ (30 and 300 microM) and Zn2+ (1, 30 and 300 microM) were added to the bath solution. ClC-2 channels are also blocked by Zn2+ and Cd2+. The magnitude of the inward conductance was dependent on the concentration of ATP in the electrode solution. The conductance was not observed when ATP in the electrode was replaced with non-hydrolysable ATP analogues [adenosine 5'-O-(3-thiotriphosphate) (ATP[gamma-S]) and 5'-adenylylimidodiphosphate (AMP-PNP)), but it was supported by UTP and GTP. These data contrast with those of previous studies in which ClC-2 channels were activated in the absence of ATP. In conclusion, the inward-rectifying Cl- channel in rat choroid plexus shares some properties with ClC-2 (inhibition by PKC and block by divalent cations), but differs in that it depends on intracellular ATP.

The chloride channel ClC-2 contributes to the inwardly rectifying Cl- conductance in cultured porcine choroid plexus epithelial cells

1. The contribution of ClC-2 protein to the inwardly rectifying Cl- conductance in cultured porcine choroid plexus epithelial cells was investigated using Western analysis and whole-cell current recordings. 2. Inwardly rectifying currents were elicited by hyperpolarizing voltage at a potential more negative than -50 mV in the presence of intracellular protein kinase A (PKA). The relative halide selectivity estimated from the shift in the reversal potential (Erev) was I- > Br- > Cl- > F-. 3. Extracellular vasoactive intestinal peptide (VIP) activated the same currents in a dose-dependent manner with a half-maximal concentration of 167.3 nM. H-89 (a PKA inhibitor) interfered with the current activation by VIP. 4. The Cl- channel was inhibited by external Cd2+, Ba2+or H+, but only weakly inhibited by known Cl- channel blockers including glibenclamide, NPPB, DIDS and anthracene-9-carboxylic acid (9AC). 5. A specific antibody to ClC-2 detected a 79 kDa protein in porcine choroid plexus cells, which was reduced in cells treated with antisense oligodeoxynucleotide for ClC-2. Both PKA and VIP failed to activate the inwardly rectifying Cl- currents in cells transfected with the antisense oligodeoxynucleotide, while they activated the currents in cells transfected with GFP alone or the control oligodeoxynucleotide randomized from antisense oligonucleotide. 6. It is concluded that ClC-2 protein contributes to the inwardly rectifying Cl- conductance in porcine choroid plexus epithelial cells.

Biological and biochemical properties of Ret with kinase domain mutations identified in multiple endocrine neoplasia type 2B and familial medullary thyroid carcinoma

Several mutations were identified in the kinase domain of the RET proto-oncogene in patients with multiple endocrine neoplasia (MEN) 2B, familial medullary thyroid carcinoma (FMTC) or sporadic medullary thyroid carcinoma. We introduced seven mutations (glutamic acid 768-->aspartic acid (E768D), valine 804-->leucine (V804L), alanine 883-->phenylalanine (A883F), serine 891-->alanine (S891A), methionine 918-->threonine (M918T), alanine 919-->proline (A919P) and E768D/A919P) into the short and long isoforms of RET cDNA and transfected the mutant cDNAs into NIH3T3 cells. The transforming activity of the long isoform of Ret with each mutation was much higher that that of its short isoform. Based on the levels of the transforming activity, these mutant RET genes were classified into two groups; a group with high transforming activity (A883F, M918T and E768D/A919P) and a group with low transforming activity (E768D, V804L, S891A and A919P) (designated high group and low group). Interestingly, the level of transforming activity correlated with clinical phenotypes; high group Ret with the A883F or M918T mutation and low group Ret with the E768D, V804L or S891A mutation were associated with the development of MEN 2B and FMTC, respectively. In addition, we found that substitution of phenylalanine for tyrosine 905 present in the kinase domain abolished both transforming and autophosphorylation activities of low group Ret whereas it did not affect the activities of high group Ret.

Whole cell Cl- conductances in mouse choroid plexus epithelial cells do not require CFTR expression

Whole cell patch-clamp studies were performed with tissue isolated from the cystic fibrosis (CF) transgenic Cftrm1cam mouse, to determine whether anion currents in choroid plexus epithelial cells require the expression of cystic fibrosis transmembrane conductance regulator (CFTR). Inclusion of 0.25 mM adenosine 3',5'-cyclic monophosphate (cAMP) and 375 nM protein kinase A (PKA) in the pipette solution caused a significant activation of a Cl(-)-selective, inward-rectifying conductance in cells from wild-type and CF mice. The small, outward currents observed in wild-type and CF animals, however, were not activated by cAMP-PKA. There were no significant differences in the size of currents between wild-type, heterozygote, and CF cells in the presence or absence of cAMP-PKA. A second whole cell conductance was activated when cells from wild-type mice were swollen. These volume-activated currents were Cl- selective and exhibited outward rectification. They were Ca2+ independent and ATP dependent and blocked by 4,4'-diisothiocyanostilbene-2,2'-disulfonic acid and 5-nitro-2-(3-phenylpropylamino)benzoic acid. The volume-activated channels were also activated in CF mutant cells, and there was no significant difference in the size of the volume-activated currents between wild-type, heterozygote, and CF cells. It is concluded that CFTR neither contributes to the whole cell conductance nor regulates the other anion conductances in choroid plexus epithelial cells.

Inhibition of the inward-rectifying Cl- channel in rat choroid plexus by a decrease in extracellular pH

1. The sensitivity of the inward-rectifying Cl- channel in choroid plexus to changes in external pH (pHo) was examined. 2. Cl- currents were recorded using whole-cell patch-clamp methods. The inward-rectifying channel was activated by 375 nM of the catalytic subunit of protein kinase A which was added to the electrode solution. 3. Reducing pHo from 7.3 to 6.5 inhibited the inward-rectifying Cl- currents, whereas an increase in current was observed when pHo was elevated to 8.5. The inhibition of the conductance exhibited a sigmoidal relationship with decreasing pH over a range of 8.5 to 5.5. A half-maximal inhibition of the current was observed at pH 7.3. 4. The inhibition of the whole-cell current by reducing pHo suggests that it is carried by channels which are distinct from other inward-rectifier Cl- channels, e.g. ClC-2, phospholemman and the channel in Xenopus oocytes.

A mini Cl- channel sensitive to external pH in the basolateral membrane of guinea-pig parietal cells

1. Voltage-independent whole-cell Cl- currents were recorded from both single, isolated parietal cells and parietal cells within gastric glands obtained from the fundus of guinea-pig stomach. 2. The Cl- currents were rapidly suppressed by a Cl- channel blocker, NPPB (5-nitro-2-(3-phenylpropylamino)-benzoate), added to the (basolateral) bathing solution in a concentration-dependent manner with a half-maximal inhibition concentration of 12 microM. 3. The selectivity sequence among anions was I- > Br- > Cl- > F-, corresponding to Eisenman's sequence I. 4. The Cl- currents were independent of cytosolic Ca2+, cyclic AMP, cyclic GMP, GTP-gamma-S and cell volume, and were not affected by application of acid secretagogues, omeprazol, arachidonic acid or prostaglandin E2. 5. Reduction of pH in the (basolateral) bathing solution immediately inhibited the Cl- current with a pK (-log of KD) of 6.3, whereas changes in intracellular pH had no effect. 6. The single-channel conductance was estimated to be 0.46-0.6 pS by variance noise analysis during inhibition of whole-cell Cl- currents by NPPB or acidic pH. 7. It is concluded that pH-sensitive 'mini' Cl- channels, with a sub-picosiemens unitary conductance, exist in the basolateral membrane of guinea-pig parietal cells.

A maxi Cl- channel coupled to endothelin B receptors in the basolateral membrane of guinea-pig parietal cells

1. To study endothelin (ET) receptors in guinea-pig stomach, ET-binding assays and in vitro autoradiography were performed on fundic cell suspensions and on sections of the fundus, respectively. ETA and ETB receptor subtypes were found to coexist in the parietal cells. 2. Endothelin 1 (ET-1) added to the (basolateral) bathing solution was found to activate noisy whole-cell Cl- currents within about 1 min in both single, isolated parietal cells and those within gastric glands obtained from the fundus. 3. ET-1-induced Cl- currents were rapidly blocked by a Cl- channel blocker (NPPB) added to the (basolateral) bathing solution in a concentration-dependent manner with a half-maximum inhibition concentration of 33 microM. 4. The anion selectivity sequence of the ET-1-induced conductance was I- > Br- > Cl- > F-, corresponding to Eisenman's sequence I. 5. Changes in extracellular pH between 5 and 8 did not affect the ET-1-induced activation of Cl- currents. 6. Similar activating effects were also observed with ET-3 and a specific ETB receptor agonist (IRL1620). An ETB receptor antagonist (IRL1720) prevented the ET-1 effect, whereas an ETA-selective antagonist (FR139317 or BQ123) failed to antagonize the ET-1 effect. 7. In the whole-cell mode, unitary Cl- channel events could be observed in association with ET-1-activated macroscopic currents. The single-channel conductances were around 200 and 350 pS at negative and positive membrane potentials, respectively. 8. It is concluded that gastric parietal cells of guinea-pig possess pH-insensitive 'maxi' Cl- channels coupled to ETB receptors in the basolateral membrane.

[Clinical evaluation of endoscopic variceal ligation (EVL)]

From August 1992 through February 1993, we treated 21 patients with endoscopic variceal ligation (EVL). Two patients had a history of the esophageal variceal bleeding, but 19 patients did not have bleeding episodes. To evaluate preventive effect of bleeding, we selected the patients who had grade F2 or red color sign positive varices. We repeated EVL until varices improved into grade F0 or F1 and red color sign negative. The therapeutic goal was sometimes changed according to patient's general condition. No additional therapy was performed to eradicate varices, such as endoscopic injection sclerotherapy. As a result of our therapy, eradication rate was 73.7% and period of hospitalization were 25 +/- 11 days. No major complications were found during and after EVL. EVL affected neither liver function test nor size of gastric varices. Recurrent varices with red color sign were found in 4 patients, but easily controlled by retreatment with EVL. EVL seems to be convenient and effective therapy in our short-term study, and useful for preventive therapy of the esophageal variceal bleeding.

Role of the medical museum in teaching medical students

We describe the Educational Museum of Modern Medicine of Kawasaki Medical School of Kurashiki, Japan, and its use in medical education. The extraordinary speed of recent medical advances confronts medical educators with many difficulties. With the aim of improving medical education at our school, we have imposed some roles of medical education, especially regarding pathology, on the medical museum, because it has attracted students to a greater extent and facilitated their independent learning in a more fruitful way than the audiovisual materials previously available in our library. We hope to provide some insights for the improvement of medical education and lead to enthusiastic discussion of this matter.