[Laparoscopic pyeloplasty combined with ultrasonic lithotripsy via nephroscope for treatment of ureteropelvic junction obstruction with renal calculi].

OBJECTIVE: To investigate the efficacy and safety of laparoscopic pyeloplasty combined with ultrasonic lithotripsy via nephroscope in the treatment of ureteropelvic junction obstruction (UPJO) with renal calculi. METHODS: From June 2016 to January 2022, eight patients including five males and three females underwent laparoscopic pyeloplasty combined with ultrasonic lithotripsy via 19.5F(1F≈0.33 mm) nephroscope in Peking University People' s Hospital. The age ranged from 23-51 years (mean: 40.5 years) and the body mass index (BMI) ranged from 18.8-32.4 kg/m2 (mean 27.0 kg/m2). The lesion located on the left side in all of the eight patients. Two patients had solitary kidney and one patient had horseshoe kidney. Solitary stone was seen in one patient and the other seven patients suffered multiple stones, with two patients had staghorn stones. The largest diameter of stones ranged from 0.6-2.5 cm (mean: 1.5 cm). CT or ultrasound showed that moderate nephrosis was seen in five patients and severe nephrosis was seen in three patients. During surgery, after exposure of renal pelvis and proximal ureter, a small incision of 1.5 cm was performed in the anterior wall of the renal pelvis, and a 19.5F nephroscope was introduced into renal pelvis through laparoscopic trocar and renal pelvis incision. Stones were fragmented and sucked out by 3.3 mm ultrasonic probe placed through nephroscope. After stones were removed, modified laparoscopic pyeloplasty was performed. RESULTS: Surgery was successfully completed in all of the eight patients without conversion to open surgery. The operation time ranged from 160-254 min (mean 213 min) and the time of nephroscopic management time was 25-40 min (mean: 33 min). The hemoglobin was decreased by 3-21 g/L (mean: 10.3 g/L). The stone-free rate was 75% (6/8 cases), stones were incompletely removed in two patients due to abnormal intrarenal structure. The modified Clavien classification system (MCCS) grade ⅢA complication occurred in one patient postoperatively, which was nephrosis due to intrarenal bleeding, and nephrostomy was performed. With the mean follow-up of 30 months (ranged from 2-68 months), there was no evidence of obstruction in all the patients, and one patient underwent percutaneous nephrolithotomy to treat residual calculi. CONCLUSION: Laparoscopic pyeloplasty combined with ultrasonic lithotripsy via 19.5F nephroscope is feasible and safe, and could be a complementary method to treat UPJO and renal calculi.

[Association between serum uric acid to creatinine ratio and metabolic syndrome based on community residents in Chashan town, Dongguan city].

Objective: To analyze the association between serum uric acid to creatinine ratio (SUA/Cr) and metabolic syndrome among community residents in Chashan town, Dongguan city. Methods: Participants were from the prospective cohort study of chronic diseases in natural populations in South China conducted in Chashan town, Dongguan city from 2018 to 2019. A total of 11 334 participants with complete data were included by using convenient sampling method. Demographic characteristics, lifestyle and health status were collected through questionnaire and physical examination. The venous blood of the subjects was collected to detect the levels of serum uric acid, creatinine and blood lipid. All participants were divided into four groups (Q1-Q4) according to the quartile of SUA/Cr level. The relationship between SUA/Cr and metabolic syndrome and its components (abdominal obesity, high triglyceride, low level of high density lipoprotein cholesterol, hypertension and abnormal glucose metabolism) were analyzed by using logistic regression model. Results: The mean age of 11 334 participants was (49.52±10.02) years. Male participants accounted for 44.2% (5 015/11 334). The prevalence of metabolic syndrome was 31.2% (3 532/11 334), and the level of SUA/Cr was 5.17±1.53. The prevalence of metabolic syndrome in group Q1-Q4 was 22.3% (631/2 834), 26.5% (752/2 833), 34.9% (988/2 833) and 41.0% (1 161/2 834), respectively. After adjusting for relevant confounding factors, the result of logistic regression model showed that compared with group Q1, the risk of metabolic syndrome in group Q2-Q4 was significantly higher, with OR (95%CI) values about 1.41 (1.23-1.60), 2.19 (1.93-2.49) and 3.01 (2.65-3.42) respectively. The risk of each component of metabolic syndrome in group Q2-Q4 was higher (Ptrend<0.001). The SUA/Cr level of participants with normal uric acid level was significantly positively correlated with metabolic syndrome. The risk of metabolic syndrome increased with the increase of SUA/Cr level, but there was the same trend without significant differences in patients with hyperuricemia (Pinteraction=0.008). Conclusion: There is a positive correlation between SUA/Cr level and the risk of metabolic syndrome among community residents in Chashan town, Dongguan city.

[Treatment of crossing vessels in laparoscopic pyeloplasty].

OBJECTIVE: To investigate the management of crossing vessels compression in laparoscopic pyeloplasty. METHODS: From January 2016 to June 2018, a total of 21 patients who were admitted to Peking University People's Hospital with ureteropelvic junction obstruction (UPJO) associated with crossing vascular compression were reviewed. There were 15 males and 6 females who formed this group, with a mean age of (33.9±15.0) years. There were 4 cases of mild hydronephrosis, 12 cases of moderate hydronephrosis and 5 cases of severe hydronephrosis before operation. All the patients underwent laparoscopic pyeloplasty in our hospital, including 13 on the left and 8 on the right. Laparoscopic pyeloplasty (Anderson-Hynes) were performed in all the patients. Hem-o-lok suspension (14 cases in the suspension group) or translocation of the crossing vessels (7 cases in the translocation group) were used for the intraoperative management of the crossing vessels. Double J tubes were removed 8 weeks postoperatively. The patient demographic data were collected (including operation time, treatment time of crossing vessels, intraoperative blood loss, time of drainage tube removal after operation, and average length of hospital stay), postoperative outcomes were evaluated and the patients were followed up regularly. RESULTS: In all the patients, the crossing vessels were successfully reserved, and none of them were ligated intra-operatively. Mean operative times were (202.2±57.0) min. The duration of intraoperative treatment of crossing vessels was (10.5±3.2) min, (6.1±2.0) min in the suspension group, and (13.7±5.2) min in the translocation group, respectively. Intraoperative blood loss was (47.8±25.6) mL, postoperative drainage time was (4.8±2.6) d, and length of hospital stay was (11.5±3.3) d. Postoperative slight urinary leakage occurred in 1 case. Preoperative pyelectasis of the affected side of all the patients was (3.4±1.7) cm, compared with postoperative pyelectasis of (1.9±1.3) cm. The difference was statistically significant (P<0.05). Postoperative follow-up of all the patients was carried out until December 2018. There was no significant difference in kidney size in all the patients before or after the operations, and hydronephrosis was alleviated compared with that before surgery. CONCLUSION: For UPJO patients with crossing vascular compression, according to the location of the crossing vessels, Hem-o-lok suspension or vessel transposition can be adopted to relieve the crossing vascular compression and improve the success rate of the surgery.

[Endoscopic treatment for ureterovesical junction stenosis in patients with kidney transplantation: 13 cases report].

OBJECTIVE: To evaluate the safety and efficacy of endoscopic treatment for ureterovesical junction (UVJ) stenosis in patients with kidney transplantation. METHODS: A retrospective study was conducted among the patients with kidney transplantation diagnosed as UVJ stenosis from 2012 March to 2018 July in Urology and Lithotripsy Center, Peking University People's Hospital. Only the patients who received endoscopic treatment were included, with staged or same-session nephrostomy followed by a retrograde ureteroscopy to evaluate the ureteral stenosis. Incisions with laser, mono- or bipolar energy, or balloon dilation were used to manage the stenosis depending on different situations. Demographic characteristics and clinical data were gathered and analyzed, including age, gender, preoperative serum creatinine, hemoglobin, operation time, success rate, postoperative serum creatinine, hemoglobin, postoperative complications rate, and long-term stenosis recurrence rate. RESULTS: In this study, 13 patients were included (9 males and 4 females). All the UVJ stenoses were diagnosed with preoperative ultrasound, CT scan, MRI, or urethrography. The mean age was 45 years (range 34-57 years). The mean preoperative serum creatinine was 243 µmol/L. Four patients developed UVJ stenosis 1 month after kidney transplantation, while the rest developed long-term stenosis. Fifteen operations were performed in all, of which 14 cases were successful while one failed. The first 8 cases received first-stage nephrostomy and second-stage endoscopic management of the stenosis, while the last 7 cases received the same session surgery. The mean operation time was 95.4 min vs. 68.9 min, and the immediate success rate was 87.5% vs. 100.0% in the first 8 cases and last 7 cases, respectively. The mean decrease of postoperative hemoglobin was 0.6 g/L and mean postoperative serum creatinine was 105 µmol/L. No postoperative fever, severe hematuria, and urine leak were observed. The mean postoperative hospital stay was 2.8 days. Three patients were able to remove ureteral stents and no recurrence was found with a follow-up time of 9, 17, and 82 months. The long-term stenosis recurrence rate was 76.9% (10/13). CONCLUSION: Endoscopic approach for the treatment of UVJ stenosis in patients with kidney transplantation was safe and efficient in our study cohort. However, long term stenosis recurrence rate was high and needed to be paid attention to.

Serum Proteomics Analysis in Rats of Immunosuppression Induced by Chronic Stress.

The immune system can be damaged by chronic stress. However, for this process, the involved molecular alterations and their regulatory roles played in immunosuppression still remain unclear. This study was aimed to identify the differences in serum protein expressions that are closely associated with the effect of chronic stress on immune function. Serum protein levels of rats in control group and chronic stress group were measured by iTRAQ analysis. Subsequently, among the 121 differentially expressed proteins screened between the two groups, 46 proteins were upregulated (>1.5-fold, P < 0.05), while 75 proteins were downregulated (<0.67-fold, P < 0.05). Bioinformatics analysis revealed that most of the differentially expressed proteins were in relation with the metabolic, cellular, response stimulus and immune system processes. The significantly differential expression of ceruloplasmin, haptoglobin, catalase and peroxiredoxin-1 were picked out for reconfirmation by ELISA analysis. The results were consistent with those obtained by iTRAQ. What is more, the roles of above-mentioned four proteins, apolipoprotein B-100 and heat-shock protein 90 in immunosuppression induced by chronic stress were discussed. Taken together, these findings may provide a new insight into better understanding the molecular mechanisms of immunosuppression induced by chronic stress.

[Comparison of three surgical methods of ureteropelvic junction obstruction in therapeutic effect and complication].

OBJECTIVE: To compare various data of open pyeloplasty, laparoscopic pyeloplasty and endopyelotomy as a treatment of ureteropelvic junction obstruction (UPJO), and to investigate and discuss the feasibility and effect of the three methods. METHODS: In the study, 109 cases of UPJO treated by different surgical approaches in Peking University People's Hospital from January 2004 to December 2014 were retrospectively investigated. The patients were divided into three groups according to the treatment they received: open peyloplasty group (32 cases), laparoscopic peyloplasty group (31 cases) and endopyelotomy group (46 cases).We compared the data of the operative time, intraoperative blood loss, perioperative complications and post-operative hospital stay among the three groups. The mean follow-up time was(51.9±40.1) months (6-132 months). RESULTS: None of the laparoscopic peyloplties was converted to open peyloplasty. All endpyelotomies were successfully completed. The operative time was as follows: laparoscopic peyloplasty group (195.97±55.22) min, open peyloplasty group (121.19±33.95) min and endopyelotomy group (74.04±33.95) min,and there were significant differences among the three groups respectively(P<0.001). There was no significant difference on the operative blood loss between open peyloplasty group and laparoscopic peyloplasty group (P=0.163). The operative blood loss of endopyelotomy group was 5(0,310)mL,which was lower than the other two groups, and this result had significant differences with the other two groups respectively(P<0.001). There were significant differences on the post-operative hospital stay (days) among open peyloplasty group, laparoscopic peyloplasty group and endopeylotomy group (P<0.05,respectively).The success rate was comparable between open peyloplasty group and laparoscopic peyloplasty group( 93.8% vs. 90.3%, P=0.672), while the endopeylotomy group had a lower success rate compared with both open surgery group and laparoscopic group(69.6% vs. 93.8%, P=0.01; 69.6% vs. 90.3%, P=0.048, respectively). The complication rates of open peyloplasty group, laparoscopic peyloplasty group and endopeylotomy group were comparable(15.6%, 16.1% and 13.0%, respectively, P>0.05). CONCLUSION: The laparoscopic peyloplasty group had a longer operative time than open peyloplasty group, while its post-operative stay was shorter. There was no significant difference on the operative blood loss between open peyloplasty group and laparoscopic peyloplasty group. Although the success rate of endopyelotomy was lower than those of the other two groups, it had advantages over the aspect of operative time, operative blood loss and post operative stay.

[Clinical manifestation and treatment of temporal bone tympanic plate fracture].

Objective: To elucidate the clinical manifestations of temporal bone tympanic plate fracture and the correlation between treatment time after injury and its prognosis, and to discuss the importance of early treatment of tympanic fracture. Methods: Retrospective analysis was carried out on the clinical data of 15 patients(17 ears)with temporal bone tympanic plate fracture from March 2006 to July 2019. The course of disease was less than 1 month (initial stage) in 7 cases (7 ears), 1 month to 6 months (middle stage) in 2 cases (3 ears), and 6 months or more (late stage) in 6 cases (7 ears). The symptoms, signs, CT findings, pure tone audiometry results, surgical methods and clinical efficacy of each group were summarized. Results: Most patients with temporal bone tympanic plate fracture were referred to otology department by maxillofacial surgery. Fracture occured indirectly with the chin or zygomatic region as the direct stress point. Thirteen of the 15 patients had mental region wounds or scars, and 14 patients had external acoustic canal bleeding immediately after injury. In the initial-stage group, hearing was mostly unchanged, while in the middle and late-stage groups, hearing loss was mainly caused by conduction factors. In the initial stage group, 6 cases/7 cases were cured by external acoustic canal packing; External acoustic canal stenosis or atresia occurred in 2 cases in the middle-stage group and were cured by external acoustic canal plasty. All the 6 patients in the late-stage group had external acoustic canal stenosis or atresia, among whom 5 patients with external acoustic canal cholesteatoma were cured by external acoustic canal plasty, and the other one patient with middle ear cholesteatoma was cured by modified radical mastoidectomy and tympanoplasty after external acoustic canal plasty for three times. Conclusions: Temporal bone tympanic plate fracture is a special type of temporal bone fracture. In the early stage of temporal bone tympanic fracture, bleeding of the external acoustic canal is the main symptom, and hearing is normal mostly. Advanced conductive deafness may result from external acoustic canal stenosis and/or cholesteatoma formation later. Bleeding of the external acoustic canal and irregular bulge of the anterior wall of the external acoustic canal with mental region wound are important signs for early diagnosis of temporal bone fracture. Temporal bone tympanic fracture should be paid attention to, early detection and timely treatment can avoid external acoustic canal stenosis and atresia.

Sirtuin inhibition and anti-cancer activities of ethyl 2-benzimidazole-5-carboxylate derivatives.

New benzimidazoles were synthesized based on the previously identified sirtuin inhibitor BZD9L1. The compounds were screened for their sirtuin (SIRT1, SIRT2 and SIRT3) inhibitory activities. Compound BZD9Q1 was determined to be a pan-SIRT1-3 inhibitor. Furthermore, the proliferation of various cancer cells was inhibited by BZD9Q1. It was shown that BZD9Q1 elicits a cytostatic effect by inducing cell cycle arrest at the G2/M phase while also showing a prominent induction of apoptosis against oral cancer cells.

Identification and characterization of a subset of mouse sensory neurons that express acid-sensing ion channel 3.

Acid-sensing ion channel 3 (ASIC3) is the most sensitive acid sensor in sensory neurons that innervate into skin, muscle, heart, and visceral tissues. ASIC3 is involved in ischemia sensing, nociception, mechanosensation, and hearing, but how ASIC3-expressing neurons differ in their firing properties is still unknown. We hypothesized that ASIC3-expressing neurons have specialized firing properties, which, coupled with the heterogeneity of acid-sensing properties, accounts for various physiological roles. Here, we successfully identified ASIC3-expressing lumbar dorsal root ganglion (DRG) neurons whose transient proton-gated currents were blocked by salicylic acid (SA). The salicylic acid-sensitive (SAS) neurons did not exist in DRG neurons of mice lacking ASIC3. SAS neurons expressed distinct electrophysiological properties as compared with other DRG neurons. Especially, SAS neurons fired action potentials (APs) with large overshoot and long afterhyperpolarization duration, which suggests that they belong to nociceptors. SAS neurons also exhibited multiple nociceptor markers such as capsaicin response (38%), action potential (AP) with inflection (35%), or tetrodotoxin resistance (31%). Only in SAS neurons but not other DRG neurons was afterhyperpolarization duration correlated with resting membrane potential and AP duration. Our studies reveal a unique feature of ASIC3-expressing DRG neurons and a basis for their heterogeneous functions.

Osteoblast interactions with various hydroxyapatite based biomaterials consolidated using a spark plasma sintering technique.

This study investigated the osteoblast behaviors on various hydroxyapatite based biomaterials that were consolidated at 1100 degrees C for 3 min by a spark plasma sintering technique. The osteoblasts from human fetal osteoblast cell line were cultured in the medium on the various biomaterials surfaces (HA, RF21, 1SiHA, and 5SiHA) to assess the cell morphology and proliferation as well as cell differentiation (alkaline phosphatase activity). Moreover, the bone gamma-carboxyglutamic protein or osteocalcin in the medium were determined at different periods of culture. The present results indicated that the amount of osteocalcin in the medium decreased during the periods of culture. The highest osteocalcin production obtained from the biomaterial 5SiHA after cell culture for 2 days demonstrated that the presence of silica in the biomaterials enhanced the cell differentiation by the rapid release of silicate and calcium ions.

Lidar observations of the diurnal variations in the depth of urban mixing layer: a case study on the air quality deterioration in Taipei, Taiwan.

An aerosol light detection and ranging (LIDAR) system was used to measure the depth of the atmospheric mixing layer over Taipei, Taiwan in the spring of 2005. This paper presents the variations of the mixing height and the mixing ratios of air pollutants during an episode of air quality deterioration (March 7-10, 2005), when Taipei was under an anti-cyclonic outflow of a traveling high-pressure system. It was found that, during those days, the urban mixing height reached its daily maximum of 1.0-1.5 km around noon and declined to 0.3-0.5 km around 18:00 (LST). In terms of hourly averages, the mixing height increased with the ambient temperature linearly by a slope of 166 m/degrees C in daytime. The consistency between the changes in the mixing height and in the ambient temperature implied that the mixing layer dynamics were dominated by solar thermal forcing. As the cap of the mixing layer descended substantially in the afternoon, reduced dispersion in the shallow mixing layer caused the concentrations of primary air pollutants to increase sharply. Consequently, the pollutant concentration exhibited an anti-correlation with the mixing height. While attentions are usually focused on the pollution problems occurring in a morning inversion layer, the results of this study indicate that the air pollution and its health impacts could be even more severe as the mixing layer is getting shallow in the afternoon.

Chemical and physiological characterization of fluo-4 Ca(2+)-indicator dyes.

We have developed fluo-4, a new fluorescent dye for quantifying cellular Ca2+ concentrations in the 100 nM to 1 microM range. Fluo-4 is similar in structure and spectral properties to the widely used fluorescent Ca(2+)-indicator dye, fluo-3, but it has certain advantages over fluo-3. Due to its greater absorption near 488 nm, fluo-4 offers substantially brighter fluorescence emission when used with excitation by argon-ion laser or other sources in conjunction with the standard fluorescein filter set. In vitro, fluo-4 exhibited high fluorescence emission, a high rate of cell permeation, and a large dynamic range for reporting [Ca2+] around a Kd(Ca2+) of 345 nM. We have also developed several Ca(2+)-indicators related to fluo-4 having lower affinities for Ca2+ that are useful in cellular studies requiring quantification of higher [Ca2+]. In a variety of physiological studies of live cells, fluo-4 labeled cells more brightly than did fluo-3, when challenged with procedures designed to elevate calcium levels. Fluo-4 is well suited for photometric and imaging applications that make use of confocal laser scanning microscopy, flow cytometry, or spectrofluorometry, or in fluorometric high-throughput microplate screening assays. Because of its higher fluorescence emission intensity, fluo-4 can be used at lower intracellular concentrations, making its use a less invasive practice.

The suppressor gene scl1+ of Saccharomyces cerevisiae is essential for growth.

In Saccharomyces cerevisiae, the SCL-1 mutation is a dominant suppressor of the cycloheximide-resistant, temperature-sensitive (ts) lethal mutation, crl3 [McCusker and Haber, Genetics 119 (1988a) 303-315]. The wild-type scl1+ gene was isolated by screening subclones of the 35-kb region between TRP5 and LEU1 for restoration of the ts phenotype in an SCL1-1 crl3-2 strain. The scl1+ mRNA is about 900 nt long and encodes an open reading frame of 810 bp. The polypeptide deduced from scl1+ possesses a putative secretory signal peptide. The 5'-noncoding region may be under multiple controls, since it contains significant homology to the consensus sequences for the DNA-binding proteins, GCN4, GFI and, possibly, TUF. Gene disruption of scl1+ demonstrates that it is an essential gene.

Human hepatitis B virus mutants: significance of molecular changes.

Human hepatitis B virus, the leading pathogen for hepatitis B, is a compact DNA virus with viral genes that largely overlap. An increasing number of mutations have emerged following human interventions such as vaccination and anti-viral therapy. While vaccine escape mutants are characterized by mutations on the antigenic hepatitis B surface antigen, those carrying mutations in other viral proteins are either resistant to anti-viral therapy or implicated in acute liver diseases. Molecular identification of these various mutants should shed new lights on the underlying mechanism of hepatitis B virus viral escape and resistance and provide helpful information on their effective eradication.

Detection of hepatitis B surface antigen mutants and their integration in human hepatocellular carcinoma.

Vaccine escape hepatitis B virus surface antigen (HBsAg) mutants are capable of independent replication and have been implicated in acute hepatitis. We now report the detection of these mutants with changes at various positions of the antigenic 'a' determinant in human hepatocellular carcinoma (HCC). Southern blot analysis indicated that the HBsAg mutant with the Glycine to Arginine change at position 145 was integrated in HCC, whereas those with a Threonine at position 133 instead of a Methionine were identified in the serum of aggressive HCC. Further studies on HBsAg mutants in HCC should provide new insights on their involvement in the hepatocarcinogenesis.

Hepatitis B virus variants with lamivudine-related mutations in the DNA polymerase and the 'a' epitope of the surface antigen are sensitive to ganciclovir.

Lamivudine is a new antiviral agent effective against hepatitis B viral (HBV) infections but can result in virus-drug resistance associated with mutations in the conserved 'YM552DD' motif of the HBV DNA polymerase. Due to their overlapping coding regions in the HBV genome, mutations in the DNA polymerase may result in substitutions in the hepatitis B surface antigen (HBsAg), albeit outside the antigenic 'a' epitope. Here we report the identification of a novel type of lamivudine-related mutations located in both the polymerase (YM552DD-->Y1552DD) and the 'a' epitope of HBsAg (Gly130-->Asp130). The same virus carried a HBsAg Gly145-->Arg145 mutation prior to therapy. Both the wild type HBV and lamivudine-related mutants with the Gly145-->Arg145 HBsAg mutation were suppressed following ganciclovir treatment, indicating a beneficial additive effect of both drugs against different forms of HBV mutants.

Intra-familial evidence of horizontal transmission of hepatitis B virus surface antigen mutant G145R.

OBJECTIVES: To provide intra-familial evidence on the horizontal transmission of hepatitis B virus surface antigen (HBsAg) mutant G145R. METHODS: Serum samples from family members of 10 vaccinated infants who carried this G145R mutant were collected. The presence of the mutant was analysed by polymerase chain reaction (PCR) and sequencing. RESULTS: The G145R mutant was identified in family members of three of the 10 infants. In family 1, the mutant found initially in child 1 was identified in another child and the father. In families 2 and 3, the G145R mutant detected previously in child 1 was detected in the father. Additional mutations in HBsAg were identified in at least two members in family 1 and 2, suggesting horizontal transmission of the mutant among them. The G145R mutant was found in samples with high levels of neutralizing antibody against HBV (anti-HBs). In addition, liver damage was seen in one G145R carrier infant. CONCLUSIONS: The G145R mutant could be transmitted horizontally among family members, and this could occur in the presence of high levels of anti-HBs. Improvement of detection system for the G145R and other HBsAg mutant will be needed for their effective control.

Probing the cathepsin D using a BODIPY FL-pepstatin A: applications in fluorescence polarization and microscopy.

Redistribution of cathepsin D, a major lysosomal aspartic endopeptidase, has been related to various pathological progressions during tumor formation and oxidation stress. We have synthesized a fluorescent probe for cathepsin D, where the pepstatin A was covalently conjugated with the BODIPY (Boron dipyrromethene difluoride) fluorophore. In vitro, BODIPY FL-pepstatin A inhibits cathepsin D activity with an IC50 of 10 nM. The nature of its binding to cathepsin D was further characterized using a fluorescence polarization measurement. Results showed that BODIPY FL-pepstatin A selectively binds to cathepsin D at pH 4.5. In fixed cells, BODIPY FL-pepstatin A stained lysosomes, where it co-localized with cathepsin D. This staining was depleted when cells were co-incubated with unlabeled pepstatin A in acidic buffer. In live cells, BODIPY FL-pepstatin A is internalized and transported to lysosomes. The staining in the lysosomes can be competed with unlabeled pepstatin A. These properties, along with the good photostability of the BODIPY FL fluorophore, make this probe a novel tool for the study of the secretion and trafficking of cathepsin D.