Yutaro Tanaka

Kidney stones have a high recurrence rate—10% within 5 years and 50% within 10. Crystalluria reflects the urinary physicochemical environment and may serve as a recurrence marker, but key crystals like brushite are rarely detected under ambient conditions. This study aimed to identify novel recurrence markers by inducing crystallization through urine cooling and analyzing crystal composition. The analyzed urine samples from 164 stone formers, including first-time stone formers (FSF, n = 77) and recurrent stone formers (RSF, n = 87). The RSF group was further stratified into low-risk ( n = 43) and high-risk ( n = 44) groups based on recurrence intervals. A 24-hour urine test assessed mineral composition and supersaturation indices. Urine samples were then cooled to induce crystallization; precipitated crystals were analyzed using microscopy and Raman spectroscopy. The presence, size, and quantity of brushite crystals were compared among the groups. Before cooling, crystals were detected in only 10.9% of samples, whereas after cooling, crystallization occurred in 76.2%, revealing six crystal types, including calcium oxalate dihydrate (COD) and brushite. COD prevalence did not differ significantly among the groups, whereas brushite crystals were significantly more frequent in the high-risk RSF (47.7%) than in low-risk RSF (16.3%) and FSF (16.9%) ( p = 0.002) groups. Additionally, the high-risk RSF group had greater quantity and larger size of brushite crystals than did other groups. Cooling-induced brushite crystallization is a promising risk marker for early stone recurrence, with higher crystal quantity and larger size strongly associated with high-risk patients. This method might enhance predictive accuracy beyond traditional 24-hour urine tests, providing a simple, cost-effective tool for recurrence prevention.

Calcium oxalate kidney stones, the most prevalent type of kidney stones, undergo a multi-step process of crystal nucleation, growth, aggregation, and secondary transition. The secondary transition has been rather overlooked, and thus, the effects on the disease and the underlying mechanism remain unclear. Here, we show, by periodic micro-CT images of human kidney stones in an ex vivo incubation experiment, that the growth of porous aggregates of calcium oxalate dihydrate (COD) crystals triggers the hardening of the kidney stones that causes difficulty in lithotripsy of kidney stone disease in the secondary transition. This hardening was caused by the internal nucleation and growth of precise calcium oxalate monohydrate (COM) crystals from isolated urine in which the calcium oxalate concentrations decreased by the growth of COD in closed grain boundaries of COD aggregate kidney stones. Reducing the calcium oxalate concentrations in urine is regarded as a typical approach for avoiding the recurrence. However, our results revealed that the decrease of the concentrations in closed microenvironments conversely promotes the transition of the COD aggregates into hard COM aggregates. We anticipate that the suppression of the secondary transition has the potential to manage the deterioration of kidney stone disease.

Objectives: To evaluate the feasibility of robot-assisted fluoroscopy-guided (RAG) puncture and to compare RAG puncture, utilizing a novel robot system for percutaneous renal access, with ultrasound-guided (USG) puncture. Materials and Methods: We conducted a benchtop study with a renal phantom model using the automated needle targeting with an X-ray system. Seventeen urologists participated in this study and performed RAG and USG phantom punctures. The number of needle punctures, device setup time, and fluoroscopic exposure duration were recorded for the analyses. Results: The single puncture success rates of the RAG and USG punctures were 100% and 70.6%, respectively ( p = 0.021). The median needle puncture time of RAG puncture was 24% shorter than that of USG puncture (35.0 vs 46.0 seconds; p < 0.001), and the median device setup time of RAG puncture was a minute longer than that of USG puncture (93.0 vs 30.5 seconds; p < 0.001). The median duration of fluoroscopic exposure of RAG puncture was longer than that of USG puncture (38.0 vs 6.5 seconds; p < 0.001). The surgeon's self-assessment results demonstrated that the participating urologists found RAG puncture to be safer and have better visibility than USG puncture; they were also more satisfied with RAG puncture. Subanalysis revealed that, in the RAG group, the attending surgeons had shorter total procedural time than the residents ( p = 0.045). Conclusion: RAG puncture showed comparable results and accuracy rates with USG puncture for renal access.

Objectives. Primary mediastinal germ cell tumors (PMGCTs) are rare, which often makes them difficult to treat. Herein, we examined patients with PMGCTs who underwent multimodal treatment.Methods. We examined 6 patients (median age: 25 years, range: 19–27 years) with PMGCTs who underwent multimodal treatment between April 2001 and March 2015. Three patients had seminomas, 2 patients had yolk sac tumors, and 1 patient had choriocarcinoma. The median observation period was 32.5 months (range: 8–84 months).Results. Three of the 6 patients received initial operation followed by 3-4 courses of chemotherapy (bleomycin, etoposide, and cisplatin (BEP) or etoposide and cisplatin (EP)). One patient developed multiple lung metastases 17 months after surgery; received salvage chemotherapy with vinblastine, ifosfamide, and cisplatin; and achieved complete remission. The remaining 3 patients received initial BEP and EP chemotherapy. Multiple lung metastases and supraclavicular lymph node metastases were detected in 2 of these patients at the initial diagnosis. The patients underwent resections to remove residual tumor after treatment, and no viable tumor cells were found.Conclusions. Reliable diagnosis and immediate multimodal treatments are necessary for patients with PMGCTs. The 6 patients treated in our hospital have never experienced recurrence after the multimodal treatment.