Tissue clearing method in visualization of cancer progression and metastasis.

Since various imaging modalities have been developed, cancer metastasis can be detected from an early stage. However, limitations still exist, especially in terms of spatial resolution. Tissue-clearing technology has emerged as a new imaging modality in cancer research, which has been developed and utilized for a long time mainly in neuroscience field. This method enables us to detect cancer metastatic foci with single-cell resolution at whole mouse body/organ level. On top of that, 3D images of cancer metastasis of whole mouse organs make it easy to understand their characteristics. Recently, further applications of tissue clearing methods were reported in combination with reporter systems, labeling, and machine learning. In this review, we would like to provide an overview of this technique and current applications in cancer research and discuss their potentials and limitations.

Alzheimer's disease associated isoforms of human CD33 distinctively modulate microglial cell responses in 5XFAD mice.

Microglia play diverse pathophysiological roles in Alzheimer's disease (AD), with genetic susceptibility factors skewing microglial cell function to influence AD risk. CD33 is an immunomodulatory receptor associated with AD susceptibility through a single nucleotide polymorphism that modulates mRNA splicing, skewing protein expression from a long protein isoform (CD33M) to a short isoform (CD33m). Understanding how human CD33 isoforms differentially impact microglial cell function in vivo has been challenging due to functional divergence of CD33 between mice and humans. We address this challenge by studying transgenic mice expressing either of the human CD33 isoforms crossed with the 5XFAD mouse model of amyloidosis and find that human CD33 isoforms have opposing effects on the response of microglia to amyloid-ß (Aß) deposition. Mice expressing CD33M have increased Aß levels, more diffuse plaques, fewer disease-associated microglia, and more dystrophic neurites compared to 5XFAD control mice. Conversely, CD33m promotes plaque compaction and microglia-plaque contacts, and minimizes neuritic plaque pathology, highlighting an AD protective role for this isoform. Protective phenotypes driven by CD33m are detected at an earlier timepoint compared to the more aggressive pathology in CD33M mice that appears at a later timepoint, suggesting that CD33m has a more prominent impact on microglia cell function at earlier stages of disease progression. In addition to divergent roles in modulating phagocytosis, scRNAseq and proteomics analyses demonstrate that CD33m+ microglia upregulate nestin, an intermediate filament involved in cell migration, at plaque contact sites. Overall, our work provides new functional insights into how CD33, as a top genetic susceptibility factor for AD, modulates microglial cell function.

High-Performance Genetically Encoded Green Fluorescent Biosensors for Intracellular l-Lactate.

l-Lactate is a monocarboxylate produced during the process of cellular glycolysis and has long generally been considered a waste product. However, studies in recent decades have provided new perspectives on the physiological roles of l-lactate as a major energy substrate and a signaling molecule. To enable further investigations of the physiological roles of l-lactate, we have developed a series of high-performance (ΔF/F = 15 to 30 in vitro), intensiometric, genetically encoded green fluorescent protein (GFP)-based intracellular l-lactate biosensors with a range of affinities. We evaluated these biosensors in cultured cells and demonstrated their application in an ex vivo preparation of Drosophila brain tissue. Using these biosensors, we were able to detect glycolytic oscillations, which we analyzed and mathematically modeled.

Tumor Embolization via the Meningohypophyseal and Inferolateral Trunk in Patients with Skull Base Tumors Using the Distal Balloon Protection Technique.

BACKGROUND AND PURPOSE: Tumor embolization through the meningohypophyseal trunk and inferolateral trunk is known to be effective in skull base tumors; however, microcatheter cannulation into these arteries is difficult, and the number of cases that can be safely embolized is limited. In this study, we present a novel embolization procedure for the meningohypophyseal trunk and inferolateral trunk using the distal balloon protection technique and detail its clinical efficacy and complication risks. We developed this procedure to allow safe embolization in patients who cannot be adequately cannulated with microcatheters into these arteries. MATERIALS AND METHODS: Patients who underwent meningohypophyseal trunk or inferolateral trunk embolization using the distal balloon protection technique for skull base tumors at our institution between 2010 and 2023 were included. In this procedure, the ICA was temporarily occluded with a balloon at the ophthalmic artery bifurcation, the microcatheter was guided to the meningohypophyseal trunk or inferolateral trunk vicinity, and embolic particles were injected into the arteries. The balloon was deflated after the embolic particles that had refluxed into the ICA were aspirated. RESULTS: A total of 25 meningohypophyseal trunks and inferolateral trunks were embolized during 21 operations. Of these 25 arteries, only 9 (36.0%) were successfully cannulated with microcatheters. Nevertheless, effective embolization was achieved in all cases. Permanent complications occurred in only 1 case (4.8%) in which the central retinal artery was occluded during inferolateral trunk embolization, resulting in a visual field defect. No permanent complications resulting from the embolic cerebral infarction were observed. Of 16 cases that underwent MR imaging within a week after embolization, however, 11 (68.8%) demonstrated embolic cerebral infarctions. CONCLUSIONS: In patients with skull base tumors with meningohypophyseal trunk or inferolateral trunk feeders that cannot be catheterized directly, embolization using the distal balloon protection technique for tumor supply can be considered as a salvage technique.

How I do it: endoscopic evacuation of intraventricular lesions using a flexible endoscope in combination with an angiographic catheter.

BACKGROUND: In intraventricular surgery using a flexible endoscope, the lesion is usually aspirated via the working channel. However, the surgical view during aspiration is extremely poor because the objective lens is located adjacent to the working channel. METHOD: To address this issue, we developed a novel surgical procedure using an angiographic catheter. In this procedure, the catheter is inserted into the working channel, and the lesion is aspirated through the catheter. Besides, continuous intraventricular irrigation is performed via the gap between the catheter and the working channel. CONCLUSION: This procedure maintains a clear view during surgery and reduces complications.

Risk of postoperative scalp necrosis in the occipital artery region after posterior cranial fossa surgery.

Ischemia-induced postoperative scalp necrosis in the superficial temporal artery (STA) region is known to occur after STA-middle cerebral artery anastomoses. However, no reports have evaluated the risk of postoperative scalp necrosis in the occipital artery (OA) region. This study examined the surgical procedures that pose a risk for postoperative scalp necrosis in the OA region following posterior cranial fossa surgery. Patients who underwent initial posterior fossa craniotomy at our institution from 2015 to 2022 were included. Clinical information was collected using medical records. Regarding surgical procedures, we evaluated the incision design and whether a supramuscular scalp flap was prepared. The supramuscular scalp flap was defined as a scalp flap dissected from the sternocleidomastoid and/or splenius capitis muscles. A total of 392 patients were included. Postoperative scalp necrosis occurred in 19 patients (4.8%). There were 296 patients with supramuscular scalp flaps, and supramuscular scalp flaps prepared in all 19 patients with postoperative necrosis. Comparing incision designs among patients with supramuscular scalp flap, a hockey stick-shaped scalp incision caused postoperative necrosis in 14 of 73 patients (19.1%), and the odds of postoperative scalp necrosis were higher with the hockey stick shape than with the retro-auricular C shape (adjusted odds ratio: 12.2, 95% confidence interval: 3.86-38.3, p = 0.00002). In all the cases, ischemia was considered to be the cause of postoperative necrosis. The incidence of postoperative necrosis is particularly high when a hockey stick-shaped scalp incision is combined with a supramuscular scalp flap.

A Patient With Exophytic Primary Optic Nerve Sheath Meningioma: Stratified Risk of Surgery Based on the Morphology.

Primary optic nerve sheath meningioma (pONSM) is one of the most challenging tumors to manage. Although surgical excision may be considered a treatment option to maintain visual function, the safety of surgery remains debatable due to the non-negligible risk of optic nerve injury. pONSM often grows concentrically around the optic nerve; however, it can also demonstrate an exophytic growth from the optic nerve. The risk of surgical excision of pONSM may vary based on the tumor's growth pattern and area of contact with the optic nerve; however, there has been no detailed report on risk stratification to date. The authors present an illustrative case of an exophytic pONSM which was removed surgically without complications, suggesting that tumor morphology may also influence the surgical risk. In this report, the imaging and intraoperative features of exophytic pONSM are presented in detail, and the risk factors for complications are discussed.

Anatomical variations and flow alterations of the uncal vein and its clinical implications in petroclival meningiomas.

BACKGROUND: The Uncal vein (UV), downstream of the deep middle cerebral vein (DMCV), has a similar drainage pattern to the superficial middle cerebral vein (SMCV) and may be involved in venous complications during the anterior transpetrosal approach (ATPA). However, in petroclival meningioma (PCM), where the ATPA is frequently used, there are no reports evaluating drainage patterns of the UV and the risk of venous complications associated with the UV during the ATPA. METHODS: Forty-three patients with petroclival meningioma (PCM) and 20 with unruptured intracranial aneurysm (control group) were included. Preoperative digital subtraction angiography was used to evaluate UV and DMCV drainage patterns on the side of the tumor and bilaterally in patients with PCM and the control group, respectively. RESULTS: In the control group, the DMCV drained to the UV, UV and BVR, and BVR in 24 (60.0%), eight (20.0%), and eight (20.0%) hemispheres, respectively. Conversely, the DMCV in the patients with PCM drained to the UV, UV and BVR, and BVR in 12 (27.9%), 19 (44.2%), and 12 (27.9%) patients, respectively. The DMCV was more likely to be drained to the BVR in the PCM group (p < 0.01). In three patients with PCM (7.0%), the DMCV drained only to the UV, and furthermore, the UV drained to the pterygoid plexus via the foramen ovale, posing a risk for venous complications during the ATPA. CONCLUSIONS: In the patients with PCM, the BVR functioned as a collateral venous pathway of the UV. Preoperative evaluation of the UV drainage patterns is recommended to reduce venous complications during the ATPA.

Biosensor Optimization Using a Förster Resonance Energy Transfer Pair Based on mScarlet Red Fluorescent Protein and an mScarlet-Derived Green Fluorescent Protein.

Genetically encoded biosensors based on Förster resonance energy transfer (FRET) are indispensable tools for monitoring biochemical changes in cells. Green and red fluorescent protein-based FRET pairs offer advantages over the classically employed cyan and yellow fluorescent protein pairs, such as better spectral separation, lower phototoxicity, and less autofluorescence. Here, we describe the development of an mScarlet-derived green fluorescent protein (designated as mWatermelon) and its use as a FRET donor to the red fluorescent protein mScarlet-I as a FRET acceptor. We tested the functionality of this FRET pair by engineering biosensors for the detection of protease activity, Ca2+, and K+. Furthermore, we described a strategy to enhance the FRET efficiency of these biosensors by modulating the intramolecular association between mWatermelon and mScarlet-I.

Intravenous sinus meningioma with intraluminal extension to the internal jugular vein: case report and review of the literature.

BACKGROUND: Meningiomas often invade venous sinuses, but intravenous sinus meningiomas remain within the intracranial cavity. This case report describes an extremely rare case of tentorial meningioma with venous sinus invasion, extending intraluminally into the lower part of the internal jugular vein in a 59-year-old man. CASE PRESENTATION: The patient's initial surgery involved the supratentorial component of a right tentorial meningioma, which invaded the right transverse and sigmoid sinuses. The supratentorial component of the tumour did not enlarge during the 2-month waiting period for the first surgery. The patient received postoperative radiation therapy for the residual tumour in the intravenous sinus. Despite radiation, the residual tumour developed caudally and ultimately extended into the right internal jugular vein. The average regrowth speed of the extracranial mass was 3.6 mm/month. The patient underwent surgery for the recurrent tumour located in the transverse sinus, sigmoid sinus, jugular bulb, and internal jugular vein, 46 months after the initial surgery. The pathological features of both surgeries were the same; WHO grade I meningothelial meningioma. CONCLUSIONS: To the best of our knowledge, there have been few case reports of benign meningioma with intraluminal extension into the internal jugular vein, and there have been no reports of long-term observation of such cases. Detailed observation of the present case suggests that the difference in growth speed between the intracranial and venous cavity depends on the surrounding environment.

Radiation-induced anterior inferior cerebellar artery pseudoaneurysm after stereotactic radiosurgery for vestibular schwannoma: features observed by direct surgery.

BACKGROUND: In vestibular schwannoma (VS) patients treated with stereotactic radiosurgery (SRS), radiation-induced pseudoaneurysm is a rare long-term complication. To the best of our knowledge, there has been only one report of direct surgery in ruptured cases, and the optimal strategy for direct surgery is yet to be clarified. This case report describes a case of ruptured VS-related SRS-induced pseudoaneurysm that was successfully treated by direct surgery. CASE PRESENTATION: A 57-year -old man underwent SRS for VS, and the tumour was well controlled after the SRS. Nine years after the SRS, however, he developed subarachnoid haemorrhage, and a SRS-induced distal anterior inferior cerebellar artery aneurysm was detected on the surface of the tumour. During the trapping surgery, the aneurysm was embedded in the tumour, and it was difficult to separate the aneurysm and tumour. Besides, the facial nerve and tumour restricted exposure of the parent artery. The parent artery proximal to the aneurysm could only be exposed by resecting caudal part of the tumour. The aneurysm was trapped with permanent clips and it was pathologically diagnosed as pseudoaneurysm. CONCLUSION: It was suggested that the VS-related SRS-induced pseudoaneurysm is tightly adhered with surrounding structures and exposure of the parent artery could be limited due to the tumour and facial nerve. In this case report, we describe detailed intraoperative findings that will be useful for developing strategies for trapping surgery in future.

The endoplasmic reticulum kinase PERK interacts with the oxidoreductase ERO1 to metabolically adapt mitochondria.

Endoplasmic reticulum (ER) homeostasis requires molecular regulators that tailor mitochondrial bioenergetics to the needs of protein folding. For instance, calnexin maintains mitochondria metabolism and mitochondria-ER contacts (MERCs) through reactive oxygen species (ROS) from NADPH oxidase 4 (NOX4). However, induction of ER stress requires a quick molecular rewiring of mitochondria to adapt to new energy needs. This machinery is not characterized. We now show that the oxidoreductase ERO1⍺ covalently interacts with protein kinase RNA-like ER kinase (PERK) upon treatment with tunicamycin. The PERK-ERO1⍺ interaction requires the C-terminal active site of ERO1⍺ and cysteine 216 of PERK. Moreover, we show that the PERK-ERO1⍺ complex promotes oxidization of MERC proteins and controls mitochondrial dynamics. Using proteinaceous probes, we determined that these functions improve ER-mitochondria Ca2+ flux to maintain bioenergetics in both organelles, while limiting oxidative stress. Therefore, the PERK-ERO1⍺ complex is a key molecular machinery that allows quick metabolic adaptation to ER stress.

Quantification of Intracellular Citrate Concentrations with Genetically Encoded Biosensors.

Citrate is a central intracellular metabolite with roles in a variety of normal and aberrant biological processes. The methods for quantifying citrate concentration in cells can enable the study of the molecular mechanisms of citrate-related biological processes and diseases. Compared to existing analytical methods such as enzymatic assays and mass spectrometry, genetically encoded biosensors based on fluorescent proteins (FPs) offer the advantage of noninvasively tracking intracellular ion and small molecule dynamics with high spatial-temporal resolution. These biosensors are less toxic than chemosensors and can be targeted to specific organelles for subcellular imaging. Here we present a protocol for quantification of cytosolic and mitochondrial citrate in mammalian cells with recently reported genetically encoded biosensors for citrate.

Evaluating diploic vein blood flow using time-resolved whole-head computed tomography angiography and determining the positional relationship between typical craniotomy approaches and diploic veins in patients with meningioma.

BACKGROUND: Diploic veins may act as collateral venous pathways in cases of meningioma with venous sinus invasion. Diploic vein blood flow should be preoperatively evaluated to consider preserving the veins. In this study, we evaluated the use of time-resolved whole-head computed tomography angiography (4D-CTA)-which is less patient-intensive than digital subtraction angiography (DSA)-for assessing diploic vein blood flow and the positional relationship between typical craniotomy approaches and diploic veins. METHODS: We retrospectively examined 231 patients who underwent surgery for intracranial meningioma. We performed contrast-enhanced magnetic resonance imaging (MRI) to evaluate diploic vein pathways and compared the visualization rates of diploic vein blood flow assessed using 4D-CTA and DSA. Subsequently, we evaluated the rates of the diploic veins transected during craniotomy by comparing the pre- and postoperative contrast-enhanced MRI. RESULTS: The diagnostic performance of 4D-CTA was assessed in 45 patients. Of the 320 diploic veins identified in these patients, blood flow in 70 (21.9%) diploic veins was identified by 4D-CTA and DSA, and both results were consistent. To assess the transection rates of the diploic veins, 150 patients were included. A trend towards a high transection rate of the diploic vein in the basal interhemispheric, frontotemporal, orbitozygomatic, combined transpetrosal, and convexity craniotomy approaches was observed. CONCLUSIONS: In patients with meningiomas, both 4D-CTA and DSA are useful in evaluating diploic vein blood flow. In meningiomas with venous sinus invasion, determining the extent of craniotomy after understanding the pathways and blood flow of diploic veins is recommended.

Factors Associated with Prolonged Impairment of Consciousness in Adult Patients Admitted for Seizures: A Comprehensive Single-center Study.

Seizures are common neurological emergencies that occasionally cause prolonged impairment of consciousness. The aim of this retrospective single-center study is to clarify factors associated with prolonged impairment of consciousness for admitted adult patients investigating patient backgrounds, blood tests, electroencephalographic patterns, and MRI findings. The patients who were admitted to the hospital due to epileptic seizures were classified into two groups: (1) early recovery group, in which patients recovered their consciousness within 6 hr, and (2) delayed recovery group, in which patients showed impairment of consciousness more than 6 hr. Factors associated with prolonged impairment of consciousness were compared between these groups. In this study, 42 cases (33 patients), with a mean age of 67.8 years, were included. Fifteen cases (13 patients) and 27 cases (20 patients) were classified into the early and delayed recovery groups, respectively. The populations of older patients and patients from a nursing home were significantly higher in the delayed recovery group. With regard to radiological analyses, a high grade of periventricular hyperintensity (PVH), high Evans index score, and enlarged bilateral atrial widths were significantly associated with prolonged impairment of consciousness. Multivariable analyses showed that a high grade of PVH was significantly associated with delayed recovery of consciousness independent of age and status epilepticus. In conclusion, we proposed that diffuse white matter degeneration around the lateral ventricles contributes to prolonged impairment of consciousness.

Inhibition of DNA Repair in Combination with Temozolomide or Dianhydrogalactiol Overcomes Temozolomide-Resistant Glioma Cells.

Resistance to temozolomide and intratumoral heterogeneity contribute to the poor prognosis of glioma. The mechanisms of temozolomide resistance can vary within a heterogeneous tumor. Temozolomide adds a methyl group to DNA. The primary cytotoxic lesion, O6-methylguanine, mispairs with thymine, leading to a futile DNA mismatch repair cycle, formation of double-strand breaks, and eventual cell death when O6-methylguanine DNA methyltransferase (MGMT) is absent. N7-methylguanine and N3-methyladenine are repaired by base excision repair (BER). The study aim was to elucidate temozolomide resistance mechanisms and identify methods to overcome temozolomide resistance in glioma. Several temozolomide-resistant clones were analyzed. Increased homologous recombination and mismatch repair system deficiencies contributed to temozolomide resistance. Inhibition of homologous recombination resensitized resistant cells with high homologous recombination efficiency. For the mismatch repair-deficient cells, inhibition of BER by PARP inhibitor potentiated temozolomide-induced cytotoxicity. Dianhydrogalactiol is a bifunctional DNA-targeting agent that forms N7-alkylguanine and inter-strand DNA crosslinks. Dianhydrogalactiol reduced the proliferation of cells independent of MGMT and mismatch repair, inducing DNA double-strand breaks and apoptosis in temozolomide-resistant cells. Further, inhibition of chk1 or homologous recombination enhanced dianhydrogalactiol-induced cytotoxicity in the cells. Selecting treatments most appropriate to the types of resistance mechanisms can potentially improve the prognosis of glioma.

Reduction of thromboembolic complications during the endovascular treatment of unruptured aneurysms by employing a tailored dual antiplatelet regimen using aspirin and prasugrel.

BACKGROUND: Thromboembolic complications (TECs) are frequent during the endovascular treatment of unruptured aneurysms. To prevent TECs, dual antiplatelet therapy using aspirin and clopidogrel is recommended for the perioperative period. In patients with a poor response, clopidogrel is a risk factor for TECs. To prevent TECs, our study assessed the stratified use of prasugrel. METHODS: Patients who underwent endovascular therapy for unruptured cerebral aneurysms from April 2017 to August 2019 were enrolled in this clinical study and given premedication with aspirin and clopidogrel for 2 weeks prior to the procedure. P2Y12 reaction units (PRU) were measured using the VerifyNow assay on the day before the procedure (tailored group). In subgroups with PRU <240, the clopidogrel dose was maintained (CPG subgroup). In subgroups with PRU ≥240, clopidogrel was changed to prasugrel (PSG subgroup). We compared the occurrence of TECs with retrospective consecutive cases from January 2015 to March 2017 without PRU assessments (non-tailored group). The frequency of TECs within 30 days was assessed as the primary endpoint. RESULTS: The tailored and non-tailored groups comprised 167 and 50 patients, respectively. TECs occurred in 11 (6.6%) and 8 (16%) patients in the tailored and non-tailored groups (P=0.048), respectively. The HR for TECs was significantly reduced in the tailored group (HR 0.3, 95% CI 0.11 to 0.81); P=0.017) compared with the non-tailored group. CONCLUSION: The results suggest that tailored dual antiplatelet therapy medication with PRU significantly reduces the frequency of TECs without increasing hemorrhagic complications.

Diploic veins as collateral venous pathways in patients with dural venous sinus invasion by meningiomas.

BACKGROUND: Although it is known that diploic veins frequently communicate with the dural venous sinuses, the role of diploic veins in patients with venous sinus invasion from meningiomas remains unknown. METHODS: We retrospectively examined the medical records of 159 patients who underwent their first craniotomies for intracranial meningiomas. Contrast-enhanced magnetic resonance imaging was used to evaluate diploic vein routes, and digital subtraction angiography (DSA) was used to evaluate diploic vein blood flow. When high blood flow was visualized concurrently with the venous sinuses, the veins were classified as of the "early type." Diploic vein routes were classified into five routes. RESULTS: DSA was performed in 110 patients, with 14 showing superior sagittal sinus (SSS) invasion (SSS group) and 23 showing non-SSS venous sinus invasion (non-SSS group). The proportion of early type diploic veins was significantly higher in the SSS group (27.1%) than in other patients (patients without venous sinus invasion, 2.1%; non-SSS, 4.3%) (p < 0.01). In patients not in the SSS group, diploic veins were sacrificed during craniotomy in 76 patients, including four patients with veins of the early type. No patients demonstrated new neurological deficits postoperatively. In the SSS group, diploic veins were sacrificed in all patients, and early type diploic veins were cut in five patients. Two of these five patients showed postoperative neurological deficits. CONCLUSIONS: In the SSS group, diploic veins may function as collateral venous pathways, and attention is recommended for their interruption. In patients without SSS invasion, diploic veins, even of the early type, can be sacrificed.

Surgical Approaches to Basilar Apex Aneurysms: An Illustrative Review.

Surgical management of basilar apex aneurysms remains one of the most challenging areas in neurovascular surgery. Technical demands of treating these aneurysms have inspired several generations of neurosurgeons to push the limitations of technical achievement. Advances in neuroanesthesia, cerebral protection paradigms, and critical care management have enhanced surgical outcomes of these lesions. Several approaches have been described to reach these lesions from anterolateral or lateral corridors. Each surgical approach has its own advantages and limitations and should be chosen for each patient according to the aneurysm's position, projection, parent arteries, and perforators. In this review, we will discuss pros and cons of the common approaches to these aneurysms with description of the important steps of each surgical procedure.