In Vivo Label-Free Observation of Tumor-Related Blood Vessels in Small Animals Using a Newly Designed Photoacoustic 3D Imaging System.

Photoacoustic (PA) technology can be used for non-invasive imaging of blood vessels. In this paper, we report on our prototype PA imaging system with a newly designed ultrasound sensor and its visualization performance of microvascular in animal. We fabricated an experimental system for animals using a high-frequency sensor. The system has two modes: still image mode by wide scanning and moving image mode by small rotation of sensor array. Optical test target, euthanized mice and rats, and live mice were used as objects. The results of optical test target showed that the spatial resolution was about two times higher than that of our conventional prototype. The image performance in vivo was evaluated in euthanized healthy mice and rats, allowing visualization of detailed blood vessels in the liver and kidneys. In tumor-bearing mice, different results of vascular induction were shown depending on the type of tumor and the method of transplantation. By utilizing the video imaging function, we were able to observe the movement of blood vessels around the tumor. We have demonstrated the feasibility of the system as a less invasive animal experimental device, as it can acquire vascular images in animals in a non-contrast and non-invasive manner.

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.

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.

Glycolytic flux controls D-serine synthesis through glyceraldehyde-3-phosphate dehydrogenase in astrocytes.

D-Serine is an essential coagonist with glutamate for stimulation of N-methyl-D-aspartate (NMDA) glutamate receptors. Although astrocytic metabolic processes are known to regulate synaptic glutamate levels, mechanisms that control D-serine levels are not well defined. Here we show that d-serine production in astrocytes is modulated by the interaction between the D-serine synthetic enzyme serine racemase (SRR) and a glycolytic enzyme, glyceraldehyde 3-phosphate dehydrogenase (GAPDH). In primary cultured astrocytes, glycolysis activity was negatively correlated with D-serine level. We show that SRR interacts directly with GAPDH, and that activation of glycolysis augments this interaction. Biochemical assays using mutant forms of GAPDH with either reduced activity or reduced affinity to SRR revealed that GAPDH suppresses SRR activity by direct binding to GAPDH and through NADH, a product of GAPDH. NADH allosterically inhibits the activity of SRR by promoting the disassociation of ATP from SRR. Thus, astrocytic production of D-serine is modulated by glycolytic activity via interactions between GAPDH and SRR. We found that SRR is expressed in astrocytes in the subiculum of the human hippocampus, where neurons are known to be particularly vulnerable to loss of energy. Collectively, our findings suggest that astrocytic energy metabolism controls D-serine production, thereby influencing glutamatergic neurotransmission in the hippocampus.

Establishment of a human allergy model using human IL-3/GM-CSF-transgenic NOG mice.

The development of animal models that mimic human allergic responses is crucial to study the pathophysiology of disease and to generate new therapeutic methodologies. Humanized mice reconstituted with human immune systems are essential to study human immune reactions in vivo and are expected to be useful for studying human allergies. However, application of this technology to the study of human allergies has been limited, largely because of the poor development of human myeloid cells, especially granulocytes and mast cells, which are responsible for mediating allergic diseases, in conventional humanized mice. In this study, we developed a novel transgenic (Tg) strain, NOD/Shi-scid-IL2rγ(null) (NOG), bearing human IL-3 and GM-CSF genes (NOG IL-3/GM-Tg). In this strain, a large number of human myeloid cells of various lineages developed after transplantation of human CD34⁺ hematopoietic stem cells. Notably, mature basophils and mast cells expressing FcεRI were markedly increased. These humanized NOG IL-3/GM-Tg mice developed passive cutaneous anaphylaxis reactions when administered anti-4-hydroxy-3-nitrophenylacetyl IgE Abs and 4-hydroxy-3-nitrophenylacetyl. More importantly, a combination of serum from Japanese cedar pollinosis patients and cedar pollen extract also elicited strong passive cutaneous anaphylaxis responses in mice. Thus, to our knowledge, our NOG IL-3/GM-Tg mice are the first humanized mouse model to enable the study of human allergic responses in vivo and are excellent tools for preclinical studies of allergic diseases.

D-amino acid oxidase controls motoneuron degeneration through D-serine.

Amyotrophic lateral sclerosis (ALS) is a fatal neurodegenerative disorder involving an extensive loss of motoneurons. Aberrant excitability of motoneurons has been implicated in the pathogenesis of selective motoneuronal death in ALS. D-serine, an endogenous coagonist of N-methyl-D-aspartate receptors, exacerbates motoneuronal death and is increased both in patients with sporadic/familial ALS and in a G93A-SOD1 mouse model of ALS (mSOD1 mouse). More recently, a unique mutation in the D-amino acid oxidase (DAO) gene, encoding a D-serine degrading enzyme, was reported to be associated with classical familial ALS. However, whether DAO affects the motoneuronal phenotype and D-serine increase in ALS remains uncertain. Here, we show that genetic inactivation of DAO in mice reduces the number and size of lower motoneurons with axonal degeneration, and that suppressed DAO activity in reactive astrocytes in the reticulospinal tract, one of the major inputs to the lower motoneurons, predominantly contributes to the D-serine increase in the mSOD1 mouse. The DAO inactivity resulted from expressional down-regulation, which was reversed by inhibitors of a glutamate receptor and MEK, but not by those of inflammatory stimuli. Our findings provide evidence that DAO has a pivotal role in motoneuron degeneration through D-serine regulation and that inactivity of DAO is a common feature between the mSOD1 ALS mouse model and the mutant DAO-associated familial ALS. The therapeutic benefit of reducing D-serine or controlling DAO activity in ALS should be tested in future studies.

Efficient xenoengraftment in severe immunodeficient NOD/Shi-scid IL2rγnull mice is attributed to a lack of CD11c+B220+CD122+ cells.

Xenograft animal models using immunodeficient mice have been widely applied in medical research on various human diseases. NOD/Shi-scid-IL2rγ(null) (NOG) mice are known to show an extremely high engraftment rate of xenotransplants compared with conventional immunodeficient mice. This high engraftment rate of xenotransplants in NOG mice was substantially suppressed by the transfer of spleen cells from NOD-scid mice that were devoid of NK cells. These results indicate that cell types other than splenic NK cells present in NOD-scid mice but not in NOG mice may be involved in this suppression. To identify the cell types responsible for this effect, we transferred subpopulations of spleen cells from NOD-scid mice into NOG mice and assessed the levels of human cell engraftment after human PBMC (hPBMC) transplantation. These experiments revealed that CD11c(+)B220(+) plasmacytoid dendritic cells (pDCs) from NOD-scid mice markedly inhibited engraftment of human cells. The CD11c(+)B220(+)CD122(+) cells further fractionated from the pDCs based on the expression of CD122, which is an NK cell marker strongly inhibited during hPBMC engraftment in NOG mice. Moreover, the CD122(+) cells in the pDC fraction were morphologically distinguishable from conventional CD122(+) NK cells and showed a higher rejection efficiency. The current results suggest that CD11c(+)B220(+)CD122(+) cells play an important role in xenograft rejection, and their absence in NOG mice may be critical in supporting the successful engraftment of xenotransplants.

Modified seromuscular patch flap for reinforcing an anastomosis site in hypopharyngeal reconstruction using free jejunal transfer: an anatomical and clinical study.

INTRODUCTION: Free jejunal transfer is commonly used as a reliable reconstructive method after total pharyngolaryngectomy. An anastomotic fistula is the most common complication in the early postoperative period, occurring in 5% to 35% of cases. There have been several studies regarding surgical techniques for minimizing fistula formation. Specifically, the vascularized seromuscular patch flap has been used for reinforcing the anastomosis site; however, this flap does not yield a sufficient range of motion because of traction on the vascular pedicle. METHODS: Between 2004 and 2011, 4 patients underwent vascularized seromuscular patch flaps with free jejunal transfer. A short segment of jejunum on a mesenteric pedicle is usually opened longitudinally along the antimesenteric border to make a patch flap; however, we made a longitudinal incision along 1 side of the mesenteric border. To investigate the vascular anatomy of the flap, a lead oxide-gelatin mixture was injected into the arterial system of 4 fresh cadavers. RESULTS: The flap had increased mobility without traction on the vascular pedicle and adequate circulation. In the injection study, it was shown that the modification guaranteed adequate circulation across the antimesenteric border and from the proximal to the distal end of the flap. CONCLUSION: In conclusion, an incision along 1 side of the mesenteric border produces increased mobility of the jejunal seromuscular patch flap. Angiography can demonstrate clear evidence of a reliable circulation.

Quantitative evaluation of lower limb varicose veins using photoacoustic imaging.

PURPOSE: Varicose veins in the lower extremities are dilated subcutaneous varicose veins with a diameter of ≥ 3 mm, caused by increased venous pressure resulting from backflow of blood due to venous valve insufficiency (Gloviczki in Handbook of venous disorders: guidelines of the American venous forum, Hodder Arnold, London, 2009). When diagnosing varicose veins, the shape and thickness of the blood vessels should be accurately visualized in three dimensions. In this study, we investigated a new method for numerical evaluation of vascular morphology related to varicose veins in the lower extremities, using a photoacoustic imaging (PAI) system, which can acquire high-resolution and three-dimensional images noninvasively. METHODS: Nine patients with varicose veins participated in the study, and their images were captured using an optical camera and PAI system. We visualized the vascular structure, created a blood presence density (BPD) heat map, and examined the correlation between BPD and location of varicose veins. RESULTS: The obtained photoacoustic (PA) images demonstrated the ability of this method to visualize vessels ranging from as small as 0.2 mm in diameter to large, dilated vessels in three dimensions. Furthermore, the study revealed a correlation between the high-density part of the BPD heat map generated from the PAI images and the presence of varicose veins. CONCLUSION: PAI is a promising technique for noninvasive and accurate diagnosis of varicose veins in the lower extremities. By providing valuable information on the morphology and hemodynamics of the varicose veins, PAI may facilitate their early detection and treatment.

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.

A DEAD-box RNA helicase Ddx54 protein in oligodendrocytes is indispensable for myelination in the central nervous system.

We recently reported that a new monoclonal antibody, 4F2, which labels oligodendroglial lineage cells, recognizes a DEAD-box RNA helicase Ddx54 and that Ddx54 binds to myelin basic protein (MBP) in brain and cultured oligodendrocytes. To elucidate the biological function of Ddx54, we generated a recombinant adenovirus, Ad-shRNA:Ddx54, expressing a short hairpin RNA to silence endogenous Ddx54 protein. The virus was intraventricularly injected into the brains of mice on postnatal day (PD) 2. The brains at PD 9 were then analyzed by immunohistochemistry. In untreated normal brain sections, as well as control brains that had been injected with Ad-ß-Gal, myelination of axons occurred in the corpus callosum with filamentous patterns of immunosignals of myelin-associated glycoprotein (MAG) and MBP. In Ad-shRNA:Ddx54-injected brain, substantial amounts of MAG and MBP immunosignals were present, but MBP immunosignals accumulated in the subplate layer and did not intrude into the emerging white matter. Immunoblot analysis revealed that Ddx54 knockdown caused a significant decrease in the level of 21.5 kDa MBP isoform and Ddx54, but the amount of Olig2; 2',3'-cyclic nucleotide 3' phosphodiesterase; MAG; three MBP isoforms (14, 17.5, and 18 kDa); and QKI-5, QKI-6, and QKI-7 proteins remained unchanged. Transfection of the Ddx54 expression vector into luciferase reporter-introduced neuroepithelial cells resulted in upregulated MBP promoter activity. Immunoprecipitation of Ddx54 protein in MBP-transfected HEK293 cells indicated that Ddx54 may directly interact with MBP mRNA. These results suggest that Ddx54 protein play an important role in central nervous system myelination, presumably in myelin sheath formation after the differentiation of oligodendrocytes.

The function of the clavicle on scapular motion: a cadaveric study.

HYPOTHESIS: The clavicle serves as a strut between the thorax and scapula, and lack of this function could affect shoulder mobility. We hypothesized that clavicular discontinuity changes shoulder kinematics, particularly affecting scapular motion. MATERIALS AND METHODS: The study used 14 cadaveric shoulders. Cadavers were stabilized in the sitting position. Manual elevation in the sagittal, scapular, and coronal planes was performed in the intact and clavicular discontinuity models. The thorax-scapula distance and 3-dimensional scapular motion during shoulder elevation were recorded using an electromagnetic tracking device. The differences between the 2 experimental models at each position were analyzed. RESULTS: Clavicular discontinuity resulted in a decreased thorax-scapula distance and in reduced external rotation, upward rotation, and posterior tilting of the scapula. The kinematic changes were observed during elevations in all 3 planes but were greatest in the sagittal plane compared with the scapular and coronal planes. CONCLUSIONS: The findings of this study revealed that discontinuity of the clavicle affects shoulder kinematics. Because of its anatomic shape and position, the clavicle stabilizes the external, upward, and posterior rotation of the scapula during arm movement. This function of the clavicle may assist glenohumeral joint motion and help prevent subacromial impingement. LEVEL OF EVIDENCE: Basic Science Study, Biomechanics, Cadaver Model.

Venous architecture of the glabellar to the forehead region.

The precise venous anatomy of the glabellar to the forehead region remains unknown. This study aimed to detail the venous architecture of the glabellar region to the forehead in conjunction with that of the supratrochlear artery to reduce the risk of venous congestion of flaps in this area. Fifteen fresh human cadavers were examined here. In five specimens, contrast medium was injected only into the venous system; in 10 specimens, two different types of contrast media were injected into the arterial and venous systems, respectively. A total of 30 hemifacial specimens were radiographed stereoscopically and observed microscopically. In all the cadavers, a distinct vein (termed as the "transverse nasal root vein") connected the bilateral angular veins. One or two large ascending veins branched from the transverse nasal root or angular vein, coursing toward the forehead skin. Numerous small veins branched out from the large ascending vein(s), forming a subdermal polygonal venous network. Small ascending veins arose from this network and coursed toward the dermis, draining venous flow from the dermis. Three different-sized valves prevented the reflux of blood in the venous pathway. The large ascending vein(s) and supratrochlear artery ran parallel only in the medial canthal area. Tiny venous vasa vasorum surrounded the adventitia of the supratrochlear artery and anastomosed with the polygonal venous network, while a few small veins from the vasa vasorum ascended toward the dermis. Understanding the venous architecture of this region is expected to facilitate the safe elevation of various flaps in the area.

Three-dimensional demonstration of the lymphatic system in the lower extremities with multi-detector-row computed tomography: a study in a cadaver model.

Sentinel lymph node biopsy (SLNB) has had a great impact on the staging and treatment of cancer. The purpose of this study was to study the lymphatic anatomy of the lower extremities by constructing three-dimensional images using multi-detector-row computed tomography (MDCT). To select appropriate contrast media for MDCT lymphatic imaging in a cadaver, we tested four kinds of contrast media by injecting them into fresh swine kidneys. After the suitable contrast medium was selected, 10 lower extremities from 5 fresh cadavers were studied. After injection of the contrast medium, each lower extremity was scanned with high-spatial-resolution MDCT. The zinc oxide mixture was found to be the most appropriate contrast formula for MDCT imaging of cadaver lymphatics in terms of CT value and no extravasation. The high-resolution MDCT imaging revealed two different superficial lymphatic pathways in the legs. One lymphatic pathway accompanying the great saphenous vein had a constant course and was connected to the superficial inguinal lymph nodes. However, another pathway, along the small saphenous vein, was variable. Some of the deep lymphatic vessels bypassed the inguinal lymph nodes. Using a new protocol, we were able to construct three-dimensional images of the lower extremity lymphatics in a cadaver model. MDCT imaging provided novel information about two different superficial lymphatic pathways in the lower extremities.

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.

Abnormal expression of TIP30 and arrested nucleocytoplasmic transport within oligodendrocyte precursor cells in multiple sclerosis.

Oligodendrocyte precursor cells (OPCs) persist near the demyelinated axons arising in MS but inefficiently differentiate into oligodendrocytes and remyelinate these axons. The pathogenesis of differentiation failure remains elusive. We initially hypothesized that injured axons fail to present Contactin, a positive ligand for the oligodendroglial Notch1 receptor to induce myelination, and thus tracked axoglial Contactin/Notch1 signaling in situ, using immunohistochemistry in brain tissue from MS patients containing chronic demyelinated lesions. Instead, we found that Contactin was saturated on demyelinated axons, Notch1-positive OPCs accumulated in Contactin-positive lesions, and the receptor was engaged, as demonstrated by cleavage to Notch1-intracellular domain (NICD). However, nuclear translocalization of NICD, required for myelinogenesis, was virtually absent in these cells. NICD and related proteins carrying nuclear localization signals were associated with the nuclear transporter Importin but were trapped in the cytoplasm. Abnormal expression of TIP30, a direct inhibitor of Importin, was observed in these OPCs. Overexpression of TIP30 in a rat OPC cell line resulted in cytoplasmic entrapment of NICD and arrest of differentiation upon stimulation with Contactin-Fc. Our results suggest that extracellular inhibitory factors as well as an intrinsic nucleocytoplasmic transport blockade within OPCs may be involved in the pathogenesis of remyelination failure in MS.

D-Ser-containing humanin shows promotion of fibril formation.

Humanin (HN), a peptide of 24 amino acid residues, suppresses the neuronal cell death that is induced by the gene products of Alzheimer's disease. HN contains two Ser residues at positions 7 and 14. Because the proportion of D-Ser isomerized from L-Ser in proteins appears to increase as cellular organs age, we explored the structural effects of the isomerization of each Ser residue in HN. By using a thioflavin-T assay to detect fibril formation, we found that an HN derivative that contained two isomerized D-Ser residues had a greater tendency to form fibrils than did wild-type HN or HNs containing single D-Ser residues. A previous report showed that HN containing two D-Ser residues exerts neuroprotective activity. Our data, therefore, suggest that the fibril formation by HN that contains two D-Ser residues may promote HN neuroprotective activity.

Alteration of intrinsic amounts of D-serine in the mice lacking serine racemase and D-amino acid oxidase.

For elucidation of the regulation mechanisms of intrinsic amounts of D-serine (D-Ser) which modulates the neuro-transmission of N-methyl-D-aspartate receptors in the brain, mutant animals lacking serine racemase (SRR) and D-amino acid oxidase (DAO) were established, and the amounts of D-Ser in the tissues and physiological fluids were determined. D-Ser amounts in the frontal brain areas were drastically decreased followed by reduced SRR activity. On the other hand, a moderate but significant decrease in D-Ser amounts was observed in the cerebellum and spinal cord of SRR knock-out (SRR(-/-)) mice compared with those of control mice, although the amounts of D-Ser in these tissues were low. The amounts of D-Ser in the brain and serum were not altered with aging. To clarify the uptake of exogenous D-Ser into the brain tissues, we have determined the D-Ser of SRR(-/-) mice after oral administration of D-Ser for the first time, and a drastic increase in D-Ser amounts in all the tested tissues was observed. Because both DAO and SRR are present in some brain areas, we have established the double mutant mice lacking SRR and DAO for the first time, and the contribution of both enzymes to the intrinsic D-Ser amounts was investigated. In the frontal brain, most of the intrinsic D-Ser was biosynthesized by SRR. On the other hand, half of the D-Ser present in the hindbrain was derived from the biosynthesis by SRR. These results indicate that the regulation of intrinsic D-Ser amounts is different depending on the tissues and provide useful information for the development of treatments for neuronal diseases.

Suppressive effects of interleukin-18 on liver function in rat liver allografts.

BACKGROUND: Interleukin-18 (IL-18) is a potent proinflammatory cytokine that augments both innate and acquired immune responses. It is also a crucial regulator of lymphocyte production of interferon-γ (IFN-γ), which can promote acute cellular rejection of transplanted solid organs. METHODS: To evaluate the role of IL-18 in liver transplantation, we constructed an adenoviral vector encoding IL-18 binding protein (Adex-IL18bp), which specifically suppressed the biologic activity of IL-18, and examined the effect of this suppression on liver allografts by using a high-responder rat model (ACI to Lewis) of orthotopic liver transplantation (OLTx). Donor rats were given one intravenous injection of Adex-IL18bp or Adex-LacZ (control vector) 2 d before OLTx. RESULTS: Seven days after OLTx, overexpression of IL-18bp resulting from the adenovirus gene transfer was associated with significantly decreased serum alanine aminotransferase levels and less histologic hepatic injury in recipient rats with Adex-IL18bp-pretreated donors compared with Adex-LacZ controls. Adex-IL18bp pretreatment also significantly prolonged rat/allograft survival, inhibited expression of IFN-γ, and reduced levels (versus control values) of both CXCL10 and CX3CL1, which can be induced by IFN-γ. CONCLUSION: These results suggest that IL-18 has an important role in liver allograft rejection through IFN-γ and chemokines and that specific suppression of IL-18 may improve liver function early after transplantation.