Focused UTUC pathways with a risk-stratified approach to diagnostic ureteroscopy: is it the need of the hour? A retrospective cohort analysis.

INTRODUCTION: Upper urinary tract urothelial cancer is a rare, aggressive variant of urinary tract cancer. There is often delay to diagnosis and management for this entity in view of diagnostic and staging challenges needing additional investigations and risk stratifications for improved outcomes. In this article, we share our experience in developing a dedicated diagnostic and treatment pathway for UTUC and assess its impact on time lines to radical nephroureterectomy (RNU). We also evaluate the impact of diagnostic ureteroscopy (DUR) on UTUC care pathways timelines. MATERIALS AND METHODS: A prospective database was maintained for all patients who underwent a RNU from January 2015 to August 2022 in a high-volume single tertiary care centre in the UK. In 2019, a Focused UTUC pathway (FUP) was implemented at the centre to streamline diagnostic and RNU pathways. A retrospective analysis of the database was conducted to compare time lines and diagnostic trends between the pre-FUP and FUP cohorts. Primary outcome measures were time to RNU from MDT. Secondary outcome measures were: impact of DUR on time to RNU from MDT and negative UTUC rates between DUR and non-DUR cohorts. Differences in continuous variables across categories were assessed using the independent sample t test. Categorical variables between cohorts were analysed using the chi-square (χ2). Statistical significance in this study was set as p < 0.05. RESULTS: A total of 500 patients with complete data were included in the analysis. The pre-FUP and FUP cohorts consisted of 313 patients and 187 patients, respectively. The overall cohort had a mean age (SD) of 70 years (9.3). 66% of the overall cohort were males. The median time to RNU from MDT in the FUP was significantly lower compared to the pre-FUP cohort; 62 days (IQR 59) vs. 48 days (IQR 41.5), p < 0.0001. The median time to RNU from MDT in patients who underwent a diagnostic URS in the FUP cohort was significantly lower compared to the pre-FUP cohort; 78.5 days (IQR 54.8) vs. 68 days (IQR 48), p-NS. The non-UTUC rates in the DUR and non-DUR cohorts were 6/248 (2.4%) and 14/251 (5.6%), respectively (NS). CONCLUSION: In this series, we illustrate the effectiveness of integrating a multidisciplinary approach with specialised personnel, ring-fenced clinics, efficient diagnostic assessment and optimised theatre capacity. By adopting a risk-stratified approach to diagnostic ureteroscopy, we have achieved a significant reduction in time to RNU.

Oncological Efficacy of Robotic Nephroureterectomy vs. Open and Laparoscopic Nephroureterectomy for Suspected Non-Metastatic UTUC-A Systematic Review and Meta-Analysis.

INTRODUCTION AND AIMS: The optimal approach for nephroureterectomy in patients with suspected UTUC remains a point of debate. In this review, we compare the oncological outcomes of robotic nephroureterectomy (RNU) with open (ONU) or laparoscopic nephroureterectomy (LNU). METHODS: All randomized trials and observational studies comparing RNU with ONU and/or LNU for suspected non-metastatic UTUC are included in this review. The systematic review was performed in accordance with the Cochrane Guidelines and the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA). The primary outcome measures were overall survival (OS), cancer-specific survival (CSS), disease-free survival (DFS), and intravesical recurrence-free survival (IV-RFS). The secondary outcome measures were the lymph node dissection (LND) rates, positive margin rates, and the proportion of patients receiving bladder intravesical chemotherapy. RESULTS: We identified 8172 references through our electronic searches and 8 studies through manual searching. A total of 15 studies met the inclusion criteria. The total number of patients in the review was 18,964. RNU had superior OS compared to LNU (HR: 0.81 (95% CI: 0.71, 0.93), p-0.002 (very low certainty)). RNU and ONU had similar OS (HR: 0.83 (95% CI: 0.52, 1.34), p-0.44 (very low certainty)). One study reported an independent association of RNU as a worse predictor of IV-RFS when compared to ONU (HR-1.73 (95% CI: 1.22, 2.45)). The LND rates were higher in the RNU cohort when compared to the LNU cohort (RR 1.24 (95% CI: 1.03, 1.51), p-0.03 (low certainty)). The positive margin rate was lower in the RNU cohort when compared to the ONU cohort (RR 0.29 (95% CI: 0.08, 0.86), p-0.03 (low certainty)). CONCLUSION: RNU offers comparable oncological efficacy to ONU, except for intravesical recurrence-free survival (IV-RFS). RNU has fewer positive surgical margin rates compared to ONU in well-balanced studies. RNU appears to outperform LNU for certain oncological parameters, such as OS and the proportion of patients who receive lymph node dissections. The quality of evidence comparing surgical techniques for UTUC has remained poor in the last decade.

Effect of ureteric access sheath on outcomes of retrograde intrarenal surgery for renal stone disease: a randomized controlled trial.

BACKGROUND: The need of ureteric access sheath (UAS) in retrograde intrarenal surgery (RIRS) has been controversial for gaining high success in terms of stone free rate (SFR), reducing operative times and complications. There has been lack of high level of evidence in the literature on this topic. MATERIALS AND METHODS: This prospective randomized controlled trial (RCT) was conducted in the Department of Urology, PGIMER, Chandigarh from July 2019 to Dec 2021. The effect of UAS on the outcome of RIRS (SFR, operative time and complications) for renal stone disease was assessed. Ninety patients were randomized into two groups: 41 patients in Group 1 (RIRS with UAS) and 40 patients in Group 2(RIRS without UAS) were finally analyzed after exclusion. All the patients underwent preoperative double J stent placement at least 10 days prior to the definitive procedure. Operative time was recorded and postoperative pain was assessed by visual analogue scale(VAS) at 6 and 24 h postoperatively. Complications and emergency visits were recorded up to one month post procedure. SFR was assessed at 1 month using noncontrast CT KUB. Success was defined as absence of any residual fragment more than 3 mm in maximum diameter. RESULTS: Demographic parameters (age, body mass index, and comorbidities) and preoperative parameters (stone burden, proportion of recurrent stone formers and proportion of patients with inferior calyceal stones) were comparable between the two groups. Operative times (45.49 vs 48.38 min; p - 0.484) and VAS scores at 6 and 24 h post-op (p - 0.577) were also comparable between Group 1 and Group 2. SFR was comparable in Group 1 and Group 2 (78.05% vs 80%, p - 0.829). Postoperative complications were higher in the UAS group, but not statistically significant (4.88% vs 0%; p - 0.157). CONCLUSION: The use of UAS during RIRS is not associated with improved SFR. RIRS can be performed safely without the use of UAS and without increasing postoperative complications.

What should urologists know about Pseudojournals and open access publishing? A narrative review of the literature.

Introduction: The majority of the open access publishing allows the researchers to publish their articles for a fee and at the same time enables the readers to access the research without paying the expensive journal subscription charges. Under the garb of open access publishing, predatory journals run a scam to dupe the researchers of money. This study was conducted to highlight the characteristics of pseudojournals and increase the awareness about their modus operandi. Methods: The email inboxes of 3 academic urologists (APS, AS, and KP) were searched for emails soliciting articles for open access journals. A list of all such journals was compiled. These journals were checked for metrics from the Journal Citation Reports and the Scimago Journal Rankings. All these journals were then cross-checked with the available whitelists and blacklists. Features pointing toward a pseudo journal were identified as red flag signs for these journals and were noted. A literature search was performed on open access publishing and predatory journals, and the salient points were noted. A checklist of red flag signs was compiled. Results: A total of 71 emails soliciting article submissions from 68 journals were received by the three urologists (APS, AS, KP). Of these, 54 were highly suggestive of being a pseudojournal, 5 journals were operating in the gray zone between genuine open access journals and outright predatory journals, and 9 were genuine open access journals. A total of 33 articles on predatory journals were reviewed after the literature search as per the PRISMA guidelines. The red flag signs identified along with the literature review were used to create the SAFEiMAP checklist, which can be used to identify predatory journals. Conclusion: Predatory journals have infiltrated the whitelists, and the indexing databases like PubMed and no blacklist is all-inclusive. Understanding the concept and the types of open access publishing gives the researchers a better idea on how to differentiate fake journals from the genuine ones. Using a checklist will help to identify the red flag signs of such journals and identify those journals that operate in the gray zone.

Quality of Life, Efficacy, and Safety of Sequential Intravesical Gemcitabine + Docetaxel versus BCG for Non-Muscle Invasive Urinary Bladder Cancer: A Pilot Study.

PURPOSE: Bacille Calmette-Guerin (BCG) is considered the most effective agent for non-muscle invasive bladder cancer (NMIBC). However, due to BCG-related toxicity, multiple studies have suggested the role of newer chemotherapeutic drugs. The aim of our study was to evaluate intravesical gemcitabine + docetaxel (Gem/Doce) versus BCG with respect to quality of life (QOL), safety, and efficacy in NMIBC. METHODS: A total of 60 patients with NMIBC were evaluated between July 2019 and December 2020 in a prospective manner. The sample size calculation was done, keeping in mind the incidence of intravesical BCG-related complications of up to 50-60% and 20-30% for Gem/Doce combination. The p value of 0.05 was kept as statistically significant. The enrollment ratio was kept at 1, and power of study was aimed at 80%. The study population was alternatively assigned to two groups (BCG vs. Gem/Doce) of 30 patients each. Both the groups received 6 weekly doses of induction therapy followed by 6 monthly doses of maintenance therapy if no recurrence was noted at interim follow-up. QOL scores, safety, and efficacy were assessed at beginning of intravesical therapy, end of induction, and 6 months of maintenance therapy. Cystoscopy examination and cytology were performed at the end of induction therapy and 3-monthly thereafter. RESULT: The preliminary results at the end of 6 months following maintenance therapy showed that the demographic profile, histological stage, and grade were comparable between two groups. The QOL scores using QLQ-30 and QLQ-BLS-24 showed statistically significant differences with the Gem/Doce arm showing better outcomes. There were no progressions to higher stage, while one recurrence each was seen in both groups. Patient-related side effects measured by CTCAE (Common Terminology Criteria for Adverse Events)version 5 showed that the BCG group had higher toxicity profile as compared to Gem/Doce group. CONCLUSION: Gem/Doce combination intravesical therapy is a promising alternative to BCG for treatment of NMIBC, showing better QOL measures and lesser side effects.

Intermittent peri-tubal instillation of dexamethasone and ropivacaine on postoperative analgesia after percutaneous nephrolithotomy: A prospective randomized controlled trial.

OBJECTIVES: Percutaneous nephrolithotomy and placement of nephrostomy tube are performed for renal stones >2 cm in diameter. Attempts have been made to infiltrate local anesthetics with or without adjuvants into the surgical site to reduce pain. We hypothesized that there would be a significant prolongation of the analgesic effect of local anesthetic instillation along the nephrostomy tube due to the adjuvant dexamethasone. METHODS: After ethical approval and Clinical Trials Registry - India registration (CTRI/2020/03/024332), 64 American Society of Anesthesiologists classification 1 and 2 adult patients were enrolled in this randomized double-blinded prospective study divided into Group R-received 20 mL 0.2% Ropivacaine and Group R + D-received 20 mL 0.2% Ropivacaine with dexamethasone 8 mg, injected through a multi-lumen wound infiltration catheter. RESULTS: The demographic profile of patients was similar in both groups. The mean duration of analgesia was longer in Group R + D (21.3 ± 2.1 hrs) versus Group R (10 ± 1.9 hrs, P = 0.001). The mean numeric rating scale scores of Group R + D were significantly lower at all time intervals (P = 0.001). Also, the cumulative dose of ropivacaine and the total use of fentanyl postoperatively in Group R was much higher (70 ± 10.4 vs 56 ± 8.9 µg, P = 0.02). The C-reactive protein levels were significantly lower in Group R + D (13.8 ± 1.5 vs 23.1 ± 1.2 mg/L, P = 0.001 and 16.5 ± 1.3 vs 28.5 ± 1.7 mg/L, P = 0.001, at 24 and 48 hrs, respectively). CONCLUSION: We conclude that dexamethasone can be used as a suitable adjuvant to intermittent local anesthetic infiltration after percutaneous nephrolithotomy with a nephrostomy tube for the prolongation of analgesia.

Role of Testicular Scintigraphy in the Assessment of Viability of Undescended Testis: Potential Pitfalls and Complementary Role of 18F FDG PET/CT.

ABSTRACT: Doppler ultrasonography and testicular scintigraphy are sensitive techniques to detect the adequacy of blood flow to testicular tissue. Because Doppler ultrasonography is an operator-dependent imaging modality, it can result in equivocal findings. Testicular scintigraphy proves to be more accurate in such cases, but it may be inconclusive on occasion. The authors report the case of a young man with a left undescended testis where testicular scintigraphy was inconclusive for viability and 18F-FDG PET/CT provided important diagnostic information.

Long-term impact of testicular torsion and its salvage on semen parameters and gonadal function.

Introduction: Testicular torsion is a urological emergency, and long-term outcomes of testicular torsion on infertility, hormonal function, and salvaged testicular size are unclear. Materials and Methods: We conducted an ambispective, observational study from January 2014 to December 2019. Baseline demographics, time of presentation, clinical features, and management details of all the patients of testicular torsion were recorded from the database. All the patients were followed up in the outpatient clinic for testicular size, hormone levels, semen analysis, and erectile function. Results: Of 85 patients, only 67 could be contacted and included in the final analysis. Group 1(orchiectomy) comprised 44 patients, and Group 2(salvage) had 23 patients. Follow-up duration ranged from 2 to 6 years and mean follow-up was 42 ± 12 months. The median time to presentation was significantly higher in Group 1 (48 hours) as compared to Group 2 (12 hours). The rate of testicular salvage did not vary with age of the patients. Doppler ultrasonography of the scrotum detected 92.5% of all cases of torsion. Antisperm antibody levels were within normal range in all patients. Approximately 47% of patients in the salvage group developed testicular atrophy on follow-up. Serum testosterone level was significantly lower in Group 1 and the subset of patients with testicular atrophy. Rest of the hormonal parameters, semen analysis, and erectile function were comparable between two groups. Conclusion: The time between onset and presentation is an important contributing factor in guiding testicular salvage. Even after salvage, many testes may atrophy on follow-up. Orchiectomy and testicular atrophy in the long term have negative impact on serum testosterone. The patients should be counseled for a long-term follow-up for the risk of testicular atrophy and low testosterone levels.

Large spontaneous steinstrasse: Our experience and management issues in tertiary care centre.

BACKGROUND: Steinstrasse, is described as array of stone pieces in the ureter following extracorporeal shock wave lithotripsy (SWL). It is well-recognized, transient event. Steinstrasse clears spontaneously, however about 6% require intervention. Spontaneous steinstrasse without prior history of SWL is a rare occurrence and only few case reports are published in literature. Objective of the study was to assess the aetiology and management issues of large spontaneous steinstrasse in our centre. METHOD: From February 2017 to March 2019, 684 patients underwent SWL for renal or ureteric stones. Twenty-eight patients presented with steinstrasse of which nine patients had no prior history of SWL. Detailed clinical profile and management issues have been discussed. RESULT: Among the nine patients of spontaneous steinstrasse, there were six males and three females. Mean age of the patients was 39 years (±13 years SD). Bilateral large spontaneous steinstrasse was seen in one out of nine patients. Seven patients had associated renal stones. Five patients presented with obstructive uropathy and three out of them had urosepsis as initial presentation. Ureterolithotomy and percutaneous nephrolithotomy were commonly performed procedures for stone clearance. Metabolic work was done in all cases in follow up period. Three patients had hypercalciuria and hypocitraturia suggestive of renal tubular acidosis. CONCLUSION: Large spontaneous steinstrasse is uncommon case scenario. It can be subtle in presentation and yet have significant patient consequence in terms of renal function and infection. Prompt management is essential to preclude permanent loss of renal function. Metabolic evaluation is indispensable in such cases.

'Pee'BuSt Trial: A single-centre prospective randomized study comparing functional and anatomic outcomes after augmentation urethroplasty with penile skin graft versus buccal mucosa graft for anterior urethral stricture disease.

PURPOSE: To assess the surgical outcomes of augmentation urethroplasty (AU) using penile skin graft (PSG) compared to buccal mucosa graft (BMG) in anterior urethral stricture disease. METHOD: Between January 2018 and January 2019, 100 patients with anterior urethral stricture planned for AU were randomized into PSG or BMG arms (CTRI/2018/07/015028). Anatomic and functional variables were compared pre-operatively and post-operatively. Primary outcome was success rate at 18 months and it was defined if any of the three criteria were met, i.e. either maximum urinary flow (Qmax) > 15 ml/s or urethral calibration of 16 French or ability to traverse the repair with 17 French cystoscope. Secondary outcomes were functional parameters such as International Prostate Symptom Score (IPSS), International Index of Erectile Function (IIEF) Score, Male Sexual Health Questionnaire for Ejaculatory Dysfunction (MSHQ-EJD), and Urethral Stricture Surgery-Patient Related Outcome Measure (USS-PROM). RESULTS: Pre-operative variables were comparable between both the arms. Median duration of follow-up was 22 months (18-24 months). At 18 months, the success rates of AU with PSG and BMG were comparable (89% v/s 91%; p = 0.70, 95% CI-0.33 to 5.21). The improvements in Qmax (p = 0.06), IPSS (p = 0.43) and USS-PROM (p = 0.49) were comparable between the two arms. There was no statistically significant difference in the IIEF-Erectile domain (p = 0.07), IIEF-Orgasmic domain (p = 0.11) and MSHQ-EJD (p = 0.20) following AU at 18 months. Clavien-Dindo grade I complications were 12.7% in PSG and 16.7% in BMG. CONCLUSION: This study provides level 1 evidence of no statistical significant difference in outcomes of AU using BMG or PSG.

Comparison of stent related symptoms in patients taking mirabegron, solifenacin, or tamsulosin: A double blinded randomized clinical trial.

BACKGROUND: The present study aims to assess the efficacy of mirabegron, a novel beta-3 agonist for ameliorating stent related symptoms (SRSs) as compared to tamsulosin and solifenacin. METHODS: Total of 150 patients undergoing ureteral stent placement following ureteroscopic lithotripsy, percutaneous nephrolithotomy, or laparoscopic/robotic pyeloplasty were randomized in 1:1:1 fashion to receive mirabegron 50 mg (group A), solifenacin 5 mg (group B), and tamsulosin 0.4 mg (group C) OD respectively. Patients were followed at POD10 (I visit), 4 weeks (II visit) after surgery, and 2 weeks post-stent removal. Validated vernacular version of ureteric stent symptoms questionnaire (USSQ) was administered to the patients at each visit. RESULTS: Out of 150 patients randomized, 123 patients (A; n = 41, B; n = 40, and C; n = 42) completed the study. The groups were comparable in terms of urinary index score of USSQ at I and II visits (p = 0.119 and 0.076, respectively). A lower proportion of patients in group B experiencing bodily pain at II visit (p = 0.039), however, pain scores were comparable. Significantly lower general health index scores were observed in group A at I visit and over 4 weeks (p = 0.007). No significant differences were observed in other domains of USSQ. Age, sex, and surgical procedure undertaken did not significantly impact the scores in various USSQ domains. CONCLUSION: Mirabegron demonstrates comparable benefit in alleviating SRSs with better general health indices and may be an effective alternative for SRSs, especially when tamsulosin or solifenacin are contra-indicated or poorly tolerated.

Primary primitive neuroectodermal tumour of the kidney in adults: Experience of managing 12 cases with systematic review and pooled analysis of literature.

INTRODUCTION: Primitive neuroectodermal tumor (PNET) of the kidney is unusual in adults. These tumours are diagnosed mainly on histopathology and that too sometimes has limitations. With this study, we aimed to review our clinical and histopathological data of patients with renal PNET and reviewing the world literature. METHODS: In this retrospective study, we reviewed our database from January 2006 to July 2018 to include all the cases of primary PNET of the kidney. We also performed systematic literature search to identify all the relevant series on renal PNET. RESULTS: A total of 12 patients including 5 men and 7 women were managed during the above mentioned period. Out of these 7 patients, 2 patients had metastasis at diagnosis, one had locally advanced disease, 6 underwent radical nephrectomy, 5 patients received adjuvant chemotherapy (two currently receiving) and only 1 patient received adjuvant radiotherapy (RT). On Immunohistochemistry (IHC), CD99 and FLI1 were positive in all the patients. Median survival was 10 months. In our review 10 studies were included, 38.6% of the patients had metastatic disease and 10.7% had locally advanced disease at diagnosis. Overall mean survival was 33.75 months. CD99 and FLI1 were positive in 94.3% and 78.5%, respectively. CONCLUSION: PNET remains a pathological diagnosis and IHC has important place in diagnosis of PNET. Locally advanced and metastatic disease is common at diagnosis leading to overall poor survival.

Unusual endophytic non-enhancing tumour in the renal pelvis: a diagnostic dilemma.

Renal cell cancer (RCC) is incidentally detected on imaging in 50%-60% of cases. Among the RCCs, clear cell variant is most common and classically seen as heterogenous enhancing lesion on CT imaging. Hypoenhancing mass presents a diagnostic dilemma with differential diagnosis being urothelial carcinoma, fat poor angiomyolipoma, oncocytoma or rarer variants of RCC. Such cases require further evaluation in form of urine cytology or newer molecular diagnostic techniques. Here, we present a case of renal mass with minimal enhancement on CT scan and imaging features suggestive of upper tract urothelial cancer. Final histopathology revealed the mass to be chromophobe variant of renal cell carcinoma.

Adrenal pheochromocytoma with involvement of aorta and left renal artery: salvaged with adrenalectomy and nephrectomy.

Large adrenal pheochromocytomas encasing the renal artery are a rare entity. The management of such challenging cases is surgical resection. The involvement of renal tissue and renal artery may necessitate meticulous dissection and concomitant nephrectomy. Here, we present a case of 41-year-old man diagnosed with left adrenal pheochromocytoma with complete encasement of left renal artery and partial encasement of aorta. Open left adrenalectomy and nephrectomy was performed after adequate preoperative optimisation. The patient is doing well at 6-month follow-up. Large adrenal pheochromocytoma with renal involvement is a rare presentation and requires optimal preoperative imaging, adequate preoperative alpha and beta blockade and meticulous surgical technique.

Conquering new battlegrounds: Successful management of isolated giant retrovesical hydatid cyst with robotic assistance.

Hydatid disease (HD) is an accidental human parasitic infestation by cestodes and is most commonly caused by Echinococcus granulosus. Liver happens to be the most common site of involvement, although involvement of other organ symptoms is not uncommon. Involvement of the retrovesical pouch by hydatidosis is generally secondary in nature with an incidence of 0.1%-0.5% only. Primary retrovesical hydatid cyst (RVHC) is extremely rare with only few cases in existing literature. RVHC can present with a wide gamut of symptoms ranging from asymptomatic to obstructive uropathy. A 38-year-old male presented to us with complaints of lower urinary tract symptoms (LUTS) and was found to have an isolated primary retrovesical hydatid cyst on evaluation. The RVHC had compressed the right ureter leading to a grossly hydronephrotic non-functional right kidney. The patient was started on albendazole therapy and underwent robot assisted right nephroureterectomy and partial pericystectomy for the RVHC. The postoperative period was uneventful with resolution of symptoms. This report highlights the various clinical presentations of RVHC as well as the minimal invasive management of this rare entity.

Development and validation of a novel prediction model for predicting renal function recovery after diversion in patients with obstructive uropathy.

OBJECTIVE: To develop and validate a novel prediction model predicting renal function recovery following diversion in patients with obstructive uropathy (OU) to the emergency department (ED). METHODS: After a systematic literature search, a novel prediction model called PGIMER Obstructive Uropathy Score (POUS) was constructed including five variables: age (<60 or >60 years), duration of symptoms (<4 or >4 weeks), presence of solitary functioning kidney, baseline hemoglobin levels and venous blood pH. This model was then validated in a prospective, observational single-center study of patients presenting with OU caused by various etiologies. Patients with OU and raised serum creatinine (>2 mg/dL) presenting to our ED were included. Renal function recovery was defined as creatinine value <1.5 mg/dL at 4 weeks following diversion. RESULTS: In this study, 174 consecutive patients with OU were recruited, and 74 (42.5%) patients had renal function recovery. All the variables included in the POUS were noted to be statistically significant on univariate analysis. On multivariate logistic regression analysis, only POUS was identified as an independent predictor of renal function recovery. On receiver operating curve analysis, the area under the curve for POUS was 0.832 for predicting recovery. A POUS of 5 or more had specificity and sensitivity of 83% and 73.6%, respectively, in predicting renal function recovery. The goodness of fit and calibration plots showed good concordance of the predicted values with the observed values. CONCLUSIONS: The POUS model is an accurate and simple-to-use tool for predicting renal function recovery. POUS model requires external validation prior to clinical use in different populations.