Yuta Murakami

Effects of a high-sodium diet on renal tubule Ca2+ transporter and claudin expression in Wistar-Kyoto rats.

BackgroundUrinary Ca2+ excretion increases with dietary NaCl. NaCl-induced calciuria may be associated with hypertension, urinary stone formation and osteoporosis, but its mechanism and long-term effects are not fully understood. This study examined alterations in the expressions of renal Ca2+ transporters, channels and claudins upon salt loading to better understand the mechanism of salt-induced urinary Ca2+ loss.MethodsEight-week old Wistar-Kyoto rats were fed either 0.3% or 8% NaCl diet for 8 weeks. Renal cortical expressions of Na+/Ca2+ exchanger 1 (NCX1), Ca2+ pump (PCMA1b), Ca2+ channel (TRPV5), calbindin-D28k, and claudins (CLDN-2, -7, -8, -16 and −19) were analyzed by quantitative PCR, western blot and/or immunohistochemistry.ResultsFractional excretion of Ca2+ increased 6.0 fold with high-salt diet. Renal cortical claudin-2 protein decreased by approximately 20% with decreased immunological staining on tissue sections. Claudin-16 and −19 expressions were not altered. Renal cortical TRPV5, calbindin-D28k and NCX1 expressions increased 1.6, 1.5 and 1.2 fold, respectively.ConclusionsChronic high-salt diet decreased claudin-2 protein and increased renal TRPV5, calbindin-D28k, and NCX1. Salt loading is known to reduce the proximal tubular reabsorption of both Na+ and Ca2+. The reduction in claudin-2 protein expression may be partly responsible for the reduced Ca2+ reabsorption in this segment. The concerted upregulation of more distal Ca2+-transporting molecules may be a physiological response to curtail the loss of Ca2+, although the magnitude of compensation does not seem adequate to bring the urinary Ca2+ excretion down to that of the normal-diet group.

Palliative shunt surgery for patients with leptomeningeal metastasis

OBJECTIVES Leptomeningeal metastasis (LM) is associated with poor prognosis and affects the quality of life (QOL) of end-stage cancer patients. Severe headache associated with hydrocephalus causes reduced QOL. We investigated the clinical value of surgical treatment for hydrocephalus in LM patients. PATIENTS AND METHODS The medical records of 11 consecutive patients who underwent lumboperitoneal shunt (LPS) or ventriculoperitoneal shunt (VPS) at our institution between 2007 and 2016 were investigated. Primary brain tumor patients were excluded. We assessed the neurological status and therapeutic effects at 1 month after the shunt surgery. RESULTS The patients were three males and eight females with a median age of 58 years (interquartile range [IR] 52-68 years). The median preoperative neutrophil-to-lymphocyte ratio was 6.4 (IR 4.8-9.2). Symptom improvement was observed in nine patients, and severe headache was relieved in seven (88%) out of eight patients. The median Karnofsky performance status scale increased from 40 to 60, and the median overall survival after primary malignancy diagnosis was 27.4 months (IR 19.6-63.1 months). The median survival after the diagnosis of brain parenchymal metastasis, LM, and shunt surgery were 7.2 months (IR 5.1-14.1 months), 3.9 months (IR 3.5-6.3 months), and 3.3 months (IR 2.9-5.7 months), respectively. CONCLUSION Shunt surgery for hydrocephalus could offer an effective palliative surgical option for symptom relief especially relief of severe headache, contributing improvement of QOL in LM patients.

Utility and safety of a novel surgical microscope laser light source

Objective Tissue injuries caused by the thermal effects of xenon light microscopes have previously been reported. Due to this, the development of a safe microscope light source became a necessity. A newly developed laser light source is evaluated regarding its effectiveness and safety as an alternative to conventional xenon light source. Methods We developed and tested a new laser light source for surgical microscopes. Four experiments were conducted to compare xenon and laser lights: 1) visual luminance comparison, 2) luminous and light chromaticity measurements, 3) examination and analysis of visual fatigue, and 4) comparison of focal temperature elevation due to light source illumination using porcine muscle samples. Results Results revealed that the laser light could be used at a lower illumination value than the xenon light (p < 0.01). There was no significant difference in visual fatigue status between the laser light and the xenon light. The laser light was superior to the xenon light regarding luminous intensity and color chromaticity. The focal temperature elevation of the muscle samples was significantly higher when irradiated with xenon light in vitro than with laser light (p < 0.01). Conclusion The newly developed laser light source is more efficient and safer than a conventional xenon light source. It lacks harmful ultraviolet waves, has a longer lifespan, a lower focal temperature than that of other light sources, a wide range of brightness and color production, and improved safety for the user’s vision. Further clinical trials are necessary to validate the impact of this new light source on the patient’s outcome and prognosis.

Multiple Surgical Treatments for Repeated Recurrence of Skull Base Mesenchymal Chondrosarcoma

We report a case of a young male who received multiple surgical treatments for repeated recurrence of skull base mesenchymal chondrosarcoma (MC). When the patient was 18 years old, we subtotally removed the skull base MC and he was treated with stereotactic radiosurgery for remnant tumors in the left cavernous sinus. After 30 months, we removed residual tumors that had regrown partially, via combined endonasal endoscopic and orbitozygomatic approaches. Over the next 65 months, the patient refused radical resection, and received six salvage surgeries, two stereotactic radiotherapies, and five stereotactic radiosurgeries for repeated recurrence. At 95 months after initial surgery, the tumors had extended to the skull base and nasal cavities. As a result, the left eye had been blinded and right visual acuity was deteriorated. We performed left anterior-middle cranial base resection, removal of nasal and intradural tumors, high flow bypass, en-bloc resection of the left cavernous sinus and clivus, and reconstruction using an abdominal flap. Even though the main tumors were removed with safety margins, tumors around the right optic nerve were removed by piecemeal to preserve right eye function. Six months after the radical resection, tumors in the right orbital apex recurred because we had been unable to remove the tumor with adequate safety margins. Skull base MC has a high tendency to recur locally, so these tumors should be radically removed with safety margins as early as possible to prevent recurrence.

A Novel Intraoperative Laser Light Imaging System to Simultaneously Visualize Visible Light and Near-Infrared Fluorescence for Indocyanine Green Videoangiography

Background: Intraoperative indocyanine green videoangiography (ICG-VA) has been reported to be utilized in various cerebrovascular surgeries, wherein the blood flow is noticeably shown in white with a black background. ICG flow alone, but not other structures, can be observed using ICG-VA. We developed a novel high-resolution intraoperative imaging system using laser light source for simultaneously visualizing both visible light and near-infrared (NIR) fluorescence images of ICG-VA. Methods: We used a novel system for 14 cerebrovascular cases. The operative field was illuminated via an operating microscope using a novel laser light source with four bands at 464 (blue), 532 (green), 640 (red), and 785 nm (NIR region). The observed light from the operative field was split using a beam splitter cube into visible (420– 660 nm) and NIR fluorescence emission light (832–900 nm). Images from the color video and NIR fluorescence emission windows were merged for visualization on a monitor screen simultaneously. Laser light was compared with xenon light, and both setups were tested for cerebrovascular surgeries. Results: Laser light has numerous advantages over xenon light. The present setup clearly visualized the color operative field with enhanced blood flow. Complete clipping or incomplete clipping with neck remnant or remnant flow into an aneurysm was confirmed in aneurysm surgeries. Feeding arteries and draining veins were easily distinguished in case of arteriovenous malformation. Conclusions: Using the present setup, we can observe the color operative field and enhanced blood flow using ICG in real time. This setup could facilitate various cerebrovascular surgeries.