Using Urine Biomarkers to Differentiate Bladder Dysfunctions in Women with Sensory Bladder Disorders.

Sensory bladder disorders encompass several distinct conditions with overlapping symptoms, which pose diagnostic challenges. This study aimed to evaluate urine biomarkers for differentiating between various sensory bladder disorders, including non-Hunner's interstitial cystitis (NHIC), detrusor overactivity (DO), hypersensitive bladder (HSB), and urodynamically normal women. A retrospective analysis of 191 women who underwent a videourodynamic study (VUDS) was conducted, with some also receiving cystoscopic hydrodistention to confirm the presence of NHIC. Participants were categorized into four groups: DO (n = 51), HSB (n = 29), NHIC (n = 81), and normal controls (n = 30). The urine levels of inflammatory and oxidative stress biomarkers were measured. The DO patients exhibited elevated IP-10 levels, while the HSB patients had decreased TAC and 8-OHdG levels. The NHIC patients showed lower IL-2 and higher TNF-α levels. A TNF-α ≥ 1.05 effectively identified NHIC, with an AUROC of 0.889, a sensitivity of 98.8%, and a specificity of 81.3%. An IP-10 ≥ 6.31 differentiated DO with an AUROC of 0.695, a sensitivity of 56.8%, and a specificity of 72.3%. An 8-OHdG ≤ 14.705 and a TAC ≤ 528.7 identified HSB with AUROCs of 0.754 and 0.844, respectively. The combination of 8-OHdG and TAC provided an AUROC of 0.853 for HSB. These findings suggest that TNF-α, IP-10, TAC, 8-OHdG, and IL-2 are promising non-invasive biomarkers for distinguishing between these conditions, which may improve diagnosis and management.

Advances in urinary biomarker discovery in urological research.

A disease-specific biomarker (or biomarkers) is a characteristic reflecting a pathological condition in human body, which can be used as a diagnostic or prognostic tool for the clinical management. A urine-based biomarker(s) may provide a clinical value as attractive tools for clinicians to utilize in the clinical setting in particular to bladder diseases including bladder cancer and other bladder benign dysfunctions. Urine can be easily obtained by patients with no preparation or painful procedures required from patients' side. Currently advanced omics technologies and computational power identified potential omics-based novel biomarkers. An unbiased profiling based on transcriptomics, proteomics, epigenetics, metabolomics approaches et al. found that expression at RNA, protein, and metabolite levels are linked with specific bladder diseases and outcomes. In this review, we will discuss about the urine-based biomarkers reported by many investigators including us and how these biomarkers can be applied as a diagnostic and prognostic tool in clinical trials and patient care to promote bladder health. Furthermore, we will discuss how these promising biomarkers can be developed into a smart medical device and what we should be cautious about toward being used in real clinical setting.

Sonographic early findings in a case of bladder schistosomiasis.

Urinary schistosomiasis is a tropical infection with a high endemicity in the developing countries and is included in the list of "Neglected Tropical Diseases". It is caused by a parasitic worm, Schistosoma haematobium, and it has come into the spotlight as a major cause of urogenital disease. Furthermore, it is linked to bladder cancer and it is a predisposing factor for HIV/AIDS. In this case, we describe a bladder schistosomal disease in a young African boy with persistent macroscopic hematuria and its ultrasound diagnostic bladder imaging.

Elevated Urine Levels of Macrophage Migration Inhibitory Factor in Inflammatory Bladder Conditions: A Potential Biomarker for a Subgroup of Interstitial Cystitis/Bladder Pain Syndrome Patients.

OBJECTIVE: To investigate whether urinary levels of macrophage migration inhibitory factor (MIF) are elevated in interstitial cystitis/bladder pain syndrome (IC/BPS) patients with Hunner lesions and also whether urine MIF is elevated in other forms of inflammatory cystitis. METHODS: Urine samples were assayed for MIF by enzyme-linked immunosorbent assay. Urine samples from 3 female groups were examined: IC/BPS patients without (N = 55) and with Hunner lesions (N = 43), and non-IC/BPS patients (N = 100; control group; no history of IC/BPS; cancer or recent bacterial cystitis). Urine samples from 3 male groups were examined: patients with bacterial cystitis (N = 50), radiation cystitis (N = 18) and noncystitis patients (N = 119; control group; negative for bacterial cystitis). RESULTS: Urine MIF (mean MIF pg/mL ± standard error of the mean) was increased in female IC/BPS patients with Hunner lesions (2159 ± 435.3) compared with IC/BPS patients without Hunner lesions (460 ± 114.5) or non-IC/BPS patients (414 ± 47.6). Receiver operating curve analyses showed that urine MIF levels discriminated between the 2 IC groups (area under the curve = 72%; confidence interval 61%-82%). Male patients with bacterial and radiation cystitis had elevated urine MIF levels (2839 ± 757.1 and 4404 ± 1548.1, respectively) compared with noncystitis patients (681 ± 75.2). CONCLUSION: Urine MIF is elevated in IC/BPS patients with Hunner lesions and also in patients with other bladder inflammatory and painful conditions. MIF may also serve as a noninvasive biomarker to select IC/BPS patients more accurately for endoscopic evaluation and possible anti-inflammatory treatment.

HIFU, a noninvasive and effective treatment for chyluria: 15 years of experience.

BACKGROUND: The current treatment therapies for chyluria are often invasive and recurrent. Here, we investigated a novel noninvasive treatment of chyluria with high-intensity focused ultrasound (HIFU) and evaluated its clinical efficacy. METHODS: 155 patients with chyluria were treated with HIFU ablation and followed up over a period of 15 years from May 2000 to December 2015. Routine examinations including urine color observation, color Doppler ultrasound examination, blood serum test of Cr, BUN, and albumin, and detection of urinary chyle were performed before and after the treatment, 1 week, 1 and 6 months post-treatment, and followed up via telephone and other forms. We lost contact with 54 patients during the course of the study. RESULTS: In the 101 complete cases, the serum levels of Cr and BUN and the color Doppler ultrasound examination did not reveal significant differences before and after the treatment. However, there was a significant increase in the hemoglobin and albumin levels, as well as the body weight after the HIFU treatment. The other 54 patients also showed an improvement of the symptoms after the HIFU treatment before losing contact. CONCLUSIONS: Our results suggest that the HIFU ablation therapy is a feasible, effective, and noninvasive method for the treatment of chyluria.

Evaluation of the Effects of Prostate Radiation Therapy on Occludin Expression and Ultrasonography Characteristics of the Bladder.

PURPOSE: To evaluate the effects of radiation dose in prostate radiation therapy (RT) on occludin expression and ultrasonography characteristics of the bladder. METHODS AND MATERIALS: Urine samples of 64 prostate RT patients were collected before, at regular intervals during, and 3 months after RT. Occludin expression analysis was performed, and bladder wall echogenicity and echotexture were investigated by ultrasound and the gray-scale histogram analysis method. The bladder equivalent uniform dose (EUD) was derived from individually produced dose treatment plan for each patient. Clinical scoring for bladder-specific symptoms was done using the Radiation Therapy Oncology Group Acute Radiation Morbidity Scoring Criteria Scale. RESULTS: Thirty patients (47%) experienced at least 1 of the studied bladder symptoms (grade ≥1 endpoints), including urinary pain, frequency, urgency, straining, incontinence, hematuria, dysuria, and nocturia. For these patients there were significant changes in urine occludin levels after starting the treatment compared with the baseline urine samples (P=.023). The mean bladder EUD that caused a significant change in occludin level, which occurred after the 15th RT session, was 26.9 Gy (range, 13.2-36.5 Gy, P=.020). In all patients a significant reduction in bladder echogenicity (P=.0137) and a significant change in its echotexture (P=.047) was found after the 10th RT session, after which the EUD to the bladder reached 17.9 Gy (range, 8.8-24.3 Gy). CONCLUSIONS: Significant changes in occludin expression level and bladder wall echogenicity and echotexture occurred during prostate RT. Our findings suggest that a significant reduction in bladder echogenicity and increase in occludin expression during treatment can be associated with acute urinary complications.

Evaluation of the diagnostic accuracy of UBC® Rapid in bladder cancer: a Swedish multicentre study.

OBJECTIVE: The aim of this study was to determine the diagnostic accuracy of UBC® Rapid - a urine-based marker for bladder cancer - in patients with bladder cancer and controls, and to compare the test results across risk groups. MATERIALS AND METHODS: This prospective phase II study was conducted at four Swedish hospitals. UBC Rapid was evaluated in four groups: A, newly diagnosed bladder cancer (n = 94); B, follow-up of non-muscle-invasive bladder cancer (n = 75); C, benign urinary tract diseases (n = 51); and D, healthy controls (n = 50). Tumours were divided into high risk (carcinoma in situ, TaG3, T1, T2 and T3) and low risk (low malignant potential, TaG1 and TaG2). Urine samples were quantitatively analysed by UBC Rapid. Sensitivity, specificity, positive predictive value (PPV) and negative predictive value (NPV) were calculated based on optimal cut-off (receiver operator characteristics curve analysis). A linear regression compared the UBC Rapid results in the different risk groups. RESULTS: The optimal cut-off was 8.1 µg/l. The median UBC Rapid values were 9.3 µg/l [interquartile range (IQR) 30.9] and 4.3 µg/l (IQR 7.8) in patients with positive and negative cystoscopy, respectively (p < .001). The value for group A was 15.6 µg/l (IQR 37.9), group B 5.6 µg/l (IQR 8.6), group C 5.1 µg/l (IQR 9.0) and group D 3.3 µg/l (IQR 7.1). Sensitivity was 70.8%, specificity 61.4%, PPV 71.3% and NPV 60.8%. The high-risk group had significantly higher UBC Rapid values than the low-risk group: 20.5 µg/l (IQR 42.2), sensitivity 79.2% and specificity 61.4% versus 7.0 µg/l (IQR 9.9), sensitivity 60.0% and specificity 61.4% (p = .039). CONCLUSIONS: The UBC Rapid urine-based marker for bladder cancer gave higher values in patients with positive than in those with negative cystoscopy. The diagnostic accuracy was better in patients with high-risk than in those with low-risk tumours, and was better during primary detection than during surveillance.

Does the Urinary Microbiome Play a Role in Urgency Urinary Incontinence and Its Severity?

OBJECTIVES: Traditionally, the urinary tract has been thought to be sterile in the absence of a clinically identifiable infection. However, recent evidence suggests that the urinary tract harbors a variety of bacterial species, known collectively as the urinary microbiome, even when clinical cultures are negative. Whether these bacteria promote urinary health or contribute to urinary tract disease remains unknown. Emerging evidence indicates that a shift in the urinary microbiome may play an important role in urgency urinary incontinence (UUI). The goal of this prospective pilot study was to determine how the urinary microbiome is different between women with and without UUI. We also sought to identify if characteristics of the urinary microbiome are associated with UUI severity. METHODS: We collected urine from clinically well-characterized women with UUI (n = 10) and normal bladder function (n = 10) using a transurethral catheter to avoid bacterial contamination from external tissue. To characterize the resident microbial community, we amplified the bacterial 16S rRNA gene by PCR and performed sequencing using Illumina MiSeq. Sequences were processed using the workflow package QIIME. We identified bacteria that had differential relative abundance between UUI and controls using DESeq2 to fit generalized linear models based on the negative binomial distribution. We also identified relationships between the diversity of the urinary microbiome and severity of UUI symptoms with Pearson's correlation coefficient. RESULTS: We successfully extracted and sequenced bacterial DNA from 95% of the urine samples and identified that there is a polymicrobial community in the female bladder in both healthy controls and women with UUI. We found the relative abundance of 14 bacteria significantly differed between control and UUI samples. Furthermore, we established that an increase in UUI symptom severity is associated with a decrease in microbial diversity in women with UUI. CONCLUSIONS: Our study provides further characterization of the urinary microbiome in both healthy controls and extensively phenotyped women with UUI. Our results also suggest that the urinary microbiome may play an important role in the pathophysiology of UUI and that the loss of microbial diversity may be associated with clinical severity.

Urinary proteomics and metabolomics studies to monitor bladder health and urological diseases.

BACKGROUND: Assays of molecular biomarkers in urine are non-invasive compared to other body fluids and can be easily repeated. Based on the hypothesis that the secreted markers from the diseased organs may locally release into the body fluid in the vicinity of the injury, urine-based assays have been considered beneficial to monitoring bladder health and urological diseases. The urine proteome is much less complex than the serum and tissues, but nevertheless can contain biomarkers for diagnosis and prognosis of diseases. The urine metabolome has a much higher number and concentration of low-molecular metabolites than the serum or tissues, with a far lower lipid concentration, yet informs directly about dietary and microbial metabolism. DISCUSSION: We here discuss the use of mass spectrometry-based proteomics and metabolomics for urine biomarker assays, specifically with respect to the underlying mechanisms that trigger the pathological condition. CONCLUSION: Molecular biomarker profiles, based on proteomics and metabolomics studies, reliably distinguish patients from healthy controls, stratify sub-populations with respect to treatment options, and predict therapeutic response of patients with urological disease.

Nonobstructive hydrocolpos due to vesicovaginal reflux: expanding the differential diagnosis.

We report the clinical details and imaging findings for a case of vesicovaginal reflux presenting as gross urocolpos in a 15-year-old female. Findings included a large fluid-filled vagina on full-bladder scan in the absence of any anatomical abnormality, which disappeared completely after micturition. It is important for radiologists to be aware of this entity as it is rarely encountered and leads to very confusing findings, which could result in an erroneous diagnosis.

Functional and molecular characterization of hyposensitive underactive bladder tissue and urine in streptozotocin-induced diabetic rat.

BACKGROUND: The functional and molecular alterations of nerve growth factor (NGF) and Prostaglandin E2 (PGE2) and its receptors were studied in bladder and urine in streptozotocin (STZ)-induced diabetic rats. METHODOLOGY/PRINCIPAL FINDINGS: Diabetes mellitus was induced with a single dose of 45 mg/kg STZ Intraperitoneally (i.p) in female Sprague-Dawley rats. Continuous cystometrogram were performed on control rats and STZ treated rats at week 4 or 12 under urethane anesthesia. Bladder was then harvested for histology, expression of EP receptors and NGF by western blotting, PGE2 levels by ELISA, and detection of apoptosis by TUNEL staining. In addition, 4-hr urine was collected from all groups for urine levels of PGE2, and NGF assay. DM induced progressive increase of bladder weight, urine production, intercontraction interval (ICI) and residual urine in a time dependent fashion. Upregulation of Prostaglandin E receptor (EP)1 and EP3 receptors and downregulation of NGF expression, increase in urine NGF and decrease levels of urine PGE2 at week 12 was observed. The decrease in ICI by intravesical instillation of PGE2 was by 51% in control rats and 31.4% in DM group at week 12. CONCLUSIONS/SIGNIFICANCE: DM induced hyposensitive underactive bladder which is characterized by increased inflammatory reaction, apoptosis, urine NGF levels, upregulation of EP1 and EP3 receptors and decreased bladder NGF and urine PGE2. The data suggest that EP3 receptor are potential targets in the treatment of diabetes induced underactive bladder.

Urinary cytopathology in primary bladder amyloidosis.

BACKGROUND: Amyloidosis results from the accumulation of unique extracellular proteins which are not able to be degraded via the usual mechanism of lysosomal proteolysis. Isolated collections of amyloid within the bladder are extremely uncommon, and a cytopathologic description in voided urine has not been described to date. METHODS: A retrospective review was performed at a tertiary-care hospital, and 3 patients with isolated bladder amyloidosis and corresponding voided urine specimens were identified. The following clinical data were collected for each case: age, gender, treatment and follow-up information. RESULTS: The patient age range was 76-84 years, with 2 males and 1 female. Amyloidosis was never clinically suspected. In 1 patient, a urinary amyloid manifested, which was thought to represent extraneous debris at the time of original diagnosis. Two patients never manifested signs of systemic amyloidosis or multiple myeloma, and the third was found to have a monoclonal gammopathy. CONCLUSIONS: Our results show the difficulty of diagnosing urinary amyloid in the absence of clinical suspicion. Further, the presence of urinary amyloid is unlikely in patients with bladder amyloidosis as the cohesive nature of the protein makes spontaneous shedding uncommon. Testing for systemic amyloidosis is warranted and if the disease is localized, a favorable outcome can be expected.

Ranolazine-induced severe bladder hypotonia.

OBJECTIVE: To describe a case of acute urinary retention due to bladder hypotonia during ranolazine treatment. CASE SUMMARY: An 81-year-old male with multiple cardiovascular diseases was hospitalized for worsening angina and heart failure symptoms. Ranolazine 375 mg twice daily was started, in addition to ongoing therapy (clopidogrel 75 mg once daily, diltiazem 60 mg 3 times daily, isosorbide mononitrate 40 mg 3 times daily, carvedilol 6.25 mg twice daily, rosuvastatin 20 mg once daily, enoxaparin 5000 IU once daily, pentoxifylline 600 mg twice daily, pantoprazole 40 mg twice daily, enalapril 20 mg twice daily, furosemide 150 mg once daily, and spironolactone 37 mg once daily). Two months later, the ranolazine dose was increased to 500 mg twice daily; shortly thereafter, acute urinary retention occurred and persisted despite institution of α-lytic (alfuzosin) and antiandrogenic (dutasteride) therapy. A urodynamic study revealed that urinary retention was caused by severe hypocontractility of the detrusor muscle. Ranolazine was withdrawn and, within 2 days, the patient recovered his ability to void spontaneously; a second urodynamic study confirmed that detrusor contractility was substantially improved. Drug rechallenge was not performed due to the patient's clinical condition. Nevertheless, a phenotyping test to assess the activity of the cytochrome isoenzymes CYP3A4 and CYP2D6 (responsible for ranolazine metabolism) was performed, with dextromethorphan used as the probe drug. The urinary metabolic ratios indicated relatively low activity for CYP3A4 and intermediate activity for CYP2D6. DISCUSSION: The causal role of ranolazine in our case of bladder hypotonia is probable according to the Naranjo criteria. The mechanism of bladder dysfunction is tentatively ascribed to blockage of late sodium current in smooth muscle cells. Although drug plasma concentrations were not measured, they were probably elevated, since the metabolic activity of CYP3A4 was at the lower end of the reference range. Enzyme inhibition produced by diltiazem may have contributed to decreasing CYP3A4 activity. CONCLUSIONS: Acute urinary retention in elderly men taking ranolazine may be due to drug-induced bladder hypotonia.

Mullerianosis of the urinary bladder: report of a case with diagnosis suggested in urine cytology and review of literature.

Mullerianosis of the urinary bladder is a rare entity characterized by the presence of an admixture of at least two types of mullerian tissue in the muscularis propria of the bladder. We report a case of mullerianosis of the urinary bladder in a 28-year-old nulliparous woman with no history of pelvic surgery or endometriosis, and the diagnosis of mullerianosis was suggested initially in urine cytopathology report. In this study, previously reported cases of mullerianosis of urinary bladder are reviewed, and differential diagnosis of endometrial-like cells in the urine has been discussed. Fewer than 20 cases of mullerianosis of the urinary bladder have been reported in the literature, and only one of these cases had cytological description in a urine specimen. Most of patients were of reproductive age ranging from 28 to 53 years and had no previous history of pelvic surgery or Cesarean section. The clinical presentations frequently were abdominal/pelvic pain and dysuria/hematuria, which may or may not be associated with menstruation. Radiologic study revealed polypoid, mass-like lesion ranging from 1 to 4.5 cm in size, predominantly involving the dome or posterior wall of the bladder. Histological sections showed two or more of the three related benign mullerian glandular epithelial proliferations-endometriosis, endosalpingiosis, and endocervicosis. Most of the patients have good prognosis with medical management.

Clinical utility of squamous and transitional nuclear structure alterations induced by Schistosoma haematobium in chronically infected adults with bladder damage verified by ultrasound in Ghana.

OBJECTIVE: To evaluate the clinical utility of quantitative nuclear morphometry--i.e., alteration in nuclear size/shape, DNA content and chromatin structure-of intact cells obtained from the sediment of urine specimens collected from people living in an area highly endemic for Schistosoma haematobium in Ghana. STUDY DESIGN: Digital images of Feulgen-DNA-stained squamous cell (SC) and transitional cell (TC) urothelial nuclei were captured using the AutoCyte imaging system, and nuclear morphometric descriptors (NMDs) were calculated. A total of 3,495 and 4,523 SC and TC nuclei from normal bladder ultrasound subjects (n =21) and 3,465 and 3,064 SC and TC nuclei from severely abnormal bladder ultrasound subjects (n = 20) were captured. RESULTS: Univariate logistic regression analyses of pooled SC and TC nuclei training sets showed that 27/40 NMDs and 24/40 NMDs were univariately significant for differentiating between SCs and TCs of subjects with normal and severely abnormal bladder ultrasound. Multivariate models constructed using NMDs with > or = 50% inclusion frequency yielded AUC-ROCs of 75.23% and 74.42% in the SC training and validation, and 69.90% and 66.70% for TC training and validation. Further, a squamous cell patient-specific model predicted severe bladder damage with an AUC-ROC of 86.90%, yielding the sensitivity, specificity and accuracy of 85.00%, 76.19% and 80.49%, respectively. CONCLUSION: Quantitative nuclear structure alterations can be used to make a noninvasive assessment of cytologic changes observed in both SC and TC bladder epithelia due to S haematobium infection.

A UK consensus on the management of the bladder in multiple sclerosis.

Bladder symptoms in multiple sclerosis (MS) are common and distressing but also highly amenable to treatment. A meeting of stakeholders involved in patients' continence care, including neurologists, urologists, primary care, MS nurses and nursing groups was recently convened to formulate a UK consensus for management. National Institute for Health and Clinical Excellence (NICE) criteria were used for producing recommendations based on a review of the literature and expert opinion. It was agreed that in the majority of cases, successful management could be based on a simple algorithm which includes using reagent sticks to test for urine infection and measurement of the post micturition residual urine volume. This is in contrast with published guidelines from other countries which recommend cystometry. Throughout the course of their disease, patients should be offered appropriate management options for treatment of incontinence, the mainstay of which is antimuscarinic medications, in combination, if necessary, with clean intermittent self-catheterisation. The evidence for other measures, including physiotherapy, alternative strategies aimed at improving bladder emptying, other medications and detrusor injections of botulinum toxin A was reviewed. The management of urinary tract infections as well as the bladder problems as part of severe disability were discussed and recommendations agreed.

Urinary glycosaminoglycans as biomarker for urothelial injury: is it possible to discriminate damage from recovery?

OBJECTIVES: The glycosaminoglycan (GAG) layer is referred to as a bladder protective factor. We reproduced an experimental model of urothelial damage to assess GAG metabolism in the process of injury and recovery of the urothelium. METHODS: Wistar female rats were bladder catheterized and instilled with either protamine sulfate (PS groups) or sterile saline (control groups). At different days after the procedure, 24-hour urine samples were obtained. The urinary levels of hyaluronic acid (HA) and sulfated glycosaminoglycan were determined in all groups and in nonmanipulated rats (day 0). Additionally, sulfated-GAG synthesis was assessed by the incorporation of [(35)S]-inorganic sulfate. The bladders were analyzed by histochemical staining for HA and immunofluorescence for heparin sulfate and syndecan-4. RESULTS: Urinary HA and sulfated-GAG were elevated after PS injection (P <0.05). A greater concentration of [(35)S]-labeled GAG in the PS group animals on the fifth day and, especially, on the seventh day represented increased GAG synthesis at these periods (P <0.05). Bladder sections from the PS group animals on day 1 showed a greater amount of HA in the urothelium. PS instillation damaged the urothelium layer of heparin sulfate and syndecan-4 seen in the control animals. On day 5, patchy areas of a restored layer were seen, and, on day 7, this layer had completely regenerated. CONCLUSIONS: Urinary GAG cannot differentiate urothelial damage from recovery. Elevated levels of urinary GAG can result from either desquamation of the surface cell GAG layer or increased GAG synthesis to regenerate the damaged urothelium.

[Effect of disturbing factors on the specificity of exfoliative urinary cytology]. / Einfluss von Störfaktoren auf die Spezifität der exfoliativen Urinzytologie.

In the clarification of hematuria and subsequent treatment, a high specificity is expected from urinary cytology when no tumor is present, because false positive results lead to unnecessary diagnostic measures. The aim of this study was to investigate different disturbing factors to determine the specificity of urinary cytology and whether the specificity can be increased by cytometry. Out of 150 patients with no malignant disease, 125 were affected by the following disturbing factors: urinary infection, urolithiasis, transurethral electroresection, utilisation of hypo-osmolar flushing solution or administration of contrast agents. In 5 patients who were diagnosed with urinary infection or urolithiasis, the urine was falsely cytologically determined to be tumor positive, an error which was corrected by cytometric analysis. Therefore, cytometric analysis should be carried out in patients in whom a tumor has been cytologically diagnosed in order to increase the specificity of urinary cytology.