Koo, Kevin

Introduction: Patients who form kidney stones are typically advised to limit intake of nondairy animal protein. Plant-based meat products may be a processed substitute protein source for these patients and have recently gained popularity because of health concerns, increased retail availability, decreased environmental impact, and meat supply shortages during the COVID-19 pandemic. Despite these perceived benefits and tangential association with whole food plant-based diets, the potential lithogenic risks associated with these products are not well characterized. Methods: The U.S. Department of Agriculture database was queried with a sample of plant-based meat products widely available to U.S. consumers. Nutrient profile data were compiled and compared with animal protein data using standardized serving sizes. Primary protein sources were identified using verified ingredient lists. Oxalate content was extrapolated based on dietary data sources. Results: A total 47 plant-based meat products (16 beef, 11 pork, 10 chicken, and 10 seafood) were analyzed. Compared with their respective animal protein, most products contained on average fewer calories (plant-based beef 77%, pork 94%, chicken 86%, and seafood 83%) and less protein (plant-based beef 68%, pork 96%, chicken 53%, and seafood 54%). Most products used soy protein as the primary protein source (55%). Soy-based beef contained the highest average oxalate content (18 mg per serving), whereas soy-based seafood contained the lowest (7 mg). The most common non-soy protein source was pea protein (30%), containing trace amounts of oxalate. Sodium content was higher in most plant-based products overall (72%) and in each category (plant-based beef 109%, pork 128%, chicken 100%, and seafood 148%). Calcium content was higher (plant-based beef 317%, pork 144%, chicken 291%, and seafood 295%) compared with animal protein. Conclusions: Most plant-based meat products consist of protein sources that are, relative to animal protein sources, higher in oxalate, sodium, and calcium. Stone-forming patients should be counseled about the potential lithogenic risk of these processed products.

Background and objectives Urinary stone disease has been associated with inflammation, but the specific cell interactions that mediate events remain poorly defined. This study compared calcification and inflammatory cell patterns in kidney tissue from radical nephrectomy specimens of patients without and with a history of urinary stone disease. Design, setting, participants, & measurements Nontumor parenchyma of biobanked radical nephrectomy specimens from age- and sex-matched stone formers ( n =44) and nonstone formers ( n =82) were compared. Calcification was detected by Yasue staining and inflammatory cell populations by immunohistochemistry for CD68 (proinflammatory M1 macrophages), CD163 and CD206 (anti-inflammatory M2 macrophages), CD3 (T lymphocytes), and tryptase (mast cells). Calcifications and inflammatory cells were quantified in cortex and medulla using Image-Pro analysis software. Results Calcification in the medulla of stone formers was higher than in nonstone formers ( P <0.001). M1 macrophages in the cortex and medulla of stone formers were greater than in nonstone formers ( P <0.001), and greater in stone former medulla than stone former cortex ( P =0.02). There were no differences in age, sex, body mass index, tumor characteristics (size, stage, or thrombus), vascular disease status, or eGFR between the groups. M2 macrophages, T lymphocytes, and mast cells did not differ by stone former status. There was a correlation between M1 macrophages and calcification in the medulla of stone formers (rho=0.48; P =0.001) and between M2 macrophages and calcification in the medulla of nonstone formers (rho=0.35; P =0.001). T lymphocytes were correlated with calcification in the cortex of both nonstone formers (rho=0.27; P =0.01) and stone formers (rho=0.42; P =0.004), whereas mast cells and calcification were correlated only in the cortex of stone formers (rho=0.35; P =0.02). Conclusions Higher medullary calcification stimulated accumulation of proinflammatory rather than anti-inflammatory macrophages in stone formers.

Introduction: Multimodal analgesic regimens incorporating peripheral nerve blocks (PNBs) have demonstrated reduced postoperative pain, opioid use, and recovery time in various disease states. However, this remains a subject of limited investigation in the percutaneous nephrolithotomy (PCNL) domain. In the face of an ongoing opioid epidemic and collective push to enhance prescribing stewardship, we sought to examine the potential opioid-sparing effect of PNBs in PCNL. Methods: A systematic review of Embase and PubMed was performed to identify all randomized controlled trials evaluating the use of a PNB with general anesthesia (GA) vs GA alone for pain control following PCNL. Studies evaluating neuraxial (epidural and spinal) anesthesia and those without GA as the control arm were excluded. Results: Seventeen trials evaluating 1,012 procedures were included. Five different blocks were identified and evaluated: paravertebral ( n = 8), intercostal nerve ( n = 3), quadratus lumborum ( n = 2), transversus abdominis plane ( n = 1), and erector spinae ( n = 3). Nine of 16 (56%) studies observed lower pain scores with PNB use throughout the 24-hour postop period. By comparison, improved pain scores with PNBs were limited to the early (<6 hours) recovery period in five studies and two found no difference. Total analgesic and opioid requirements were significantly higher in the GA control arm in nearly all studies (12/14, 86%). Operative times were similar and there were no differences in rates of intercostal access or nephrostomy tube insertion between study arms in any trial. Conclusions: While greater analgesic use with GA alone likely minimizes or obscures differences in patient-reported pain scores, PNBs may offer a significant opioid-sparing analgesic effect during postoperative recovery after PCNL.