Renal Stone Characterization using High Resolution Imaging Mode on a Photon Counting Detector CT System

In addition to the standard-resolution (SR) acquisition mode, a high-resolution (HR) mode is available on a research photon-counting-detector (PCD) whole-body CT system. In the HR mode each detector consists of a 2x2 array of 0.225 mm × 0.225 mm subpixel elements. This is in contrast to the SR mode that consists of a 4x4 array of the same sub-elements, and results in 0.25 mm isotropic resolution at iso-center for the HR mode. In this study, we quantified ex vivo the capabilities of the HR mode to characterize renal stones in terms of morphology and mineral composition. Forty pure stones - 10 uric acid (UA), 10 cystine (CYS), 10 calcium oxalate monohydrate (COM) and 10 apatite (APA) - and 14 mixed stones were placed in a 20 cm water phantom and scanned in HR mode, at radiation dose matched to that of routine dual-energy stone exams. Data from micro CT provided a reference for the quantification of morphology and mineral composition of the mixed stones. The area under the ROC curve was 1.0 for discriminating UA from CYS, 0.89 for CYS vs COM and 0.84 for COM vs APA. The root mean square error (RMSE) of the percent UA in mixed stones was 11.0% with a medium-sharp kernel and 15.6% with the sharpest kernel. The HR showed qualitatively accurate characterization of stone morphology relative to micro CT.

Activation of Piezo1 Inhibits Kidney Cystogenesis

The disruption of calcium signaling associated with polycystin deficiency has been proposed as the primary event underlying the increased abnormally patterned epithelial cell growth characteristic of Polycystic Kidney Disease. Calcium can be regulated through mechanotransduction, and the mechanosensitive cation channel Piezo1 has been implicated in sensing of intrarenal pressure and in urinary osmoregulation. However, a possible role for PIEZO1 in kidney cystogenesis remains undefined. We hypothesized that cystogenesis in ADPKD reflects altered mechanotransduction, suggesting activation of mechanosensitive cation channels as a therapeutic strategy for ADPKD. Here, we show that Yoda-1 activation of PIEZO1 increases intracellular Ca 2+ and reduces forskolin-induced cAMP levels in mIMCD3 cells. Yoda-1 reduced forskolin-induced IMCD cyst surface area in vitro and in mouse metanephros ex vivo in a dose-dependent manner. Knockout of polycystin-2 dampened the efficacy of PIEZO1 activation in reducing both cAMP levels and cyst surface area in IMCD3 cells. However, collecting duct-specific Piezo1 knockout neither induced cystogenesis in wild-type mice nor affected cystogenesis in the Pkd1 RC/RC model of ADPKD. Our study suggests that polycystin-2 and PIEZO1 play a role in mechanotransduction during cystogenesis in vitro , and ex vivo , but that in vivo cyst expansion may require inactivation or repression of additional suppressors of cystogenesis and/or growth. Our study provides a preliminary proof of concept for PIEZO1 activation as a possible component of combination chemotherapy to retard or halt cystogenesis and/or cyst growth.

Activation of PIEZO1 Attenuates Kidney Cystogenesis In Vitro and Ex Vivo

Key Points

Background

The disruption of calcium signaling associated with polycystin deficiency is a key factor in abnormal epithelial growth in autosomal dominant polycystic kidney disease. Calcium homeostasis can be influenced by mechanotransduction. The mechanosensitive cation channel PIEZO1 has been implicated in sensing intrarenal pressure and regulating urinary osmoregulation, but its role in kidney cystogenesis is unclear.

Methods

We hypothesized that altered mechanotransduction contributes to cystogenesis in autosomal dominant polycystic kidney disease and that activation of mechanosensitive cation channels could be a therapeutic strategy.

Results

We demonstrate that Yoda1, a PIEZO1 activator, increases intracellular calcium and reduces forskolin-induced cAMP levels in mouse inner medullary collecting duct (mIMCD3) cells. Notably, knockout of polycystin-2 attenuated the efficacy of Yoda1 in reducing cAMP levels in mIMCD3 cells. Yoda1 also reduced forskolin-induced mIMCD3 cyst surface area in vitro and cystic index in mouse metanephros ex vivo in a dose-dependent manner. However, collecting duct–specific PIEZO1 knockout neither induced cystogenesis in wild-type mice nor altered cystogenesis in the Pkd1RC/RC mouse model.

Conclusions

These findings support the potential role of PIEZO1 agonists in mitigating cystogenesis by increasing intracellular calcium and reducing cAMP levels, but the unaltered in vivo cystic phenotype after PIEZO1 knockout in the collecting duct suggests possible redundancy in mechanotransductive pathways.

Inclusivity of patients in early phase breast cancer clinical trials

INTRODUCTION

Studies have shown that certain groups of patients are underrepresented in clinical trials including non-Caucasian ethnicity, poor fluency in English, low socioeconomic status, older age, neurodivergence, and large Body Mass Index (BMI). There is a need to ensure adequate representation of these groups so that the results of any trial accurately reflect the population. The aim of this study was to review the pathway of patients recruited into two early phase breast cancer clinical and determine the inclusivity of patients from the aforementioned sub-groups.

METHODS

The Breast Cancer Research Database was reviewed, and the characteristics of all patients who were screened for eligibility in two early phase clinical trials was examined. The English Indices of Deprivation was used to populate the Index of Multiple Deprivation (IMD) for each patient using their postcode.

RESULTS

In total, 392 patients were eligible to participate, between September 2020 to May 2023. Of these, 144 (36.7 %) were recruited to these two trials. In all, 100 % of patients eligible for these trials were approached and screened for participation. Eligible patients had a mean age of 53.5 years. Recruited patients were younger on average than those not recruited (49.1 years vs 56.0 years, p<0.0001). Only one recruited patient required an interpreter, compared with 24 (9.7 %%) of those who were not recruited (p<0.001). There was no difference in the IMD (p=0.38), BMI (p=0.34) and neurodiversity (p=0.10) between patients recruited into clinical trials and those who were not.

CONCLUSION

Older age and poor fluency in the English language remain barriers to participation in early-phase clinical trials despite implementing a clear pathway to trial recruitment. There is a pressing need to address these barriers by raising awareness, improve appropriate training and providing comprehensive trial information to patients in the language of their choice.