Pentafecta evaluation in robot-assisted radical prostatectomy by risk group.

OBJECTIVE: Radical prostatectomy is a therapeutic option in organ-confined prostate cancer. As the development of robotic systems progresses, the approach with this technology has begun to impact the functional and oncological outcomes of urological patients. The objective is to report the rate of pentafecta in patients undergoing robot-assisted radical prostatectomy (RARP) stratified by risk groups. METHOD: Retrospective, observational, descriptive study from 2013 to 2020 that included 112 patients undergoing RARP. RESULTS: A rate of pentafecta at 12 months of follow-up of 35.7% (n = 40) was obtained. In the subanalysis by risk groups, at 1-year follow-up, was obtained an index of 43% (n = 26), 26% (n = 9) and 22% (n = 4) in low-, intermediate-, and high-risk patients, respectively. CONCLUSIONS: Prostatectomy showed functional and oncological results similar to those reported in the literature with robotic approach, regardless of the risk group for prostate cancer.

OBJETIVO: La prostatectomía radical es la alternativa terapéutica de elección en el cáncer de próstata confinado al órgano. Conforme avanza el desarrollo de los sistemas robóticos, el abordaje con esta tecnología ha comenzado a impactar en los desenlaces funcionales y oncológicos de los pacientes urológicos. El objetivo es reportar el índice de pentafecta en pacientes sometidos a prostatectomía radical asistida por robot (PRRA) estratificados por grupos de riesgo. MÉTODO: Estudio retrospectivo, observacional, descriptivo, de 2013 a 2020, que incluyó 112 pacientes sometidos a PRAR. RESULTADOS: Se obtuvo un índice de pentafecta a 12 meses de seguimiento del 35.7% (n = 40). En el subanálisis por grupos de riesgo, al año de seguimiento, se obtuvieron unos índices del 43% (n = 26), el 26% (n = 9) y el 22% (n = 4) en los pacientes de bajo, intermedio y alto riesgo, respectivamente. CONCLUSIONES: La prostatectomía demostró resultados funcionales y oncológicos similares a lo reportado en la literatura con abordaje robótico independientemente del grupo de riesgo del cáncer de próstata.

[Robot-assisted radical prostatectomy with Retzius-Sparing approach vs. modified Frankfurt: comparison of results at 1 year of follow-up]. / Prostatectomía radical asistida por robot con abordaje Retzius-Sparing vs. Frankfurt modificado: comparación de resultados a 1 año de seguimiento.

Background: Robot-assisted radical prostatectomy has positioned itself as the approach of choice in the treatment of prostate cancer. Objective: To compare the outcomes of robot-assisted radical prostatectomy using the Retzius-Sparing (RS) approach against the modified Frankfurt (MF) technique. Method: To describe the perioperative, functional and oncological outcomes of 13 patients with prostate cancer who underwent RS robotic radical prostatectomy compared to MF, evaluating pathological results, urinary continence, sexual function and oncological control in 1 year of follow-up. Results: The average age was 64 years in RS group vs. 61 years in MF group. The values of total prostate antigen were higher in the RS group (25 ng/dl) vs. MF group (11 ng/dl). The volume of gland in RS group was 40.62 ml vs. 63.33 ml in the RS group. All patients were bilaterally neuropreserved, being statistically significant in favor of MF group (p = 0.016). Positive surgical margins were higher in R-S group (38.4%) vs. MF group (33.3%). Conclusions: With RS the same tendency to urinary continence is observed, with a significant difference in erectile function in favor of MF. This preliminary study shows better impact on erectile function.

Antecedentes: La prostatectomía radical asistida por robot se ha posicionado como el abordaje de elección en el tratamiento del cáncer de próstata. Objetivo: Comparar los resultados de la prostatectomía radical asistida por robot utilizando el abordaje Retzius-Sparing (RS) contra el Frankfurt modificado (FM). Método: Se describen los desenlaces perioperatorios, funcionales y oncológicos de 13 pacientes con cáncer de próstata que fueron llevados a prostatectomía radical robótica con RS, en comparación con FM, y se evalúan los resultados patológicos, continencia urinaria, función sexual y control oncológico a 1 año de seguimiento. Resultados: La media de edad fue de 64 años en el grupo RS y de 61 años en el grupo FM. Los valores de antígeno prostático total fueron mayores en el grupo RS (25 ng/dl) que en el FM (11 ng/dl). El volumen de la glándula fue menor en el grupo RS (40.62 ml) que en el FM (63.33 ml). Todos los pacientes fueron neuropreservados bilateralmente, siendo la diferencia estadísticamente significativa a favor de FM (p = 0.016). Los márgenes quirúrgicos positivos fueron mayores en el grupo RS (38.4%) que en el FM (33.3%). Conclusiones: Con RS se observa la misma tendencia a la continencia urinaria, con diferencia significativa en la función eréctil a favor de FM. Este estudio preliminar muestra mejor impacto en la función eréctil.

Long-term oncological and surgical outcomes after Video Endoscopic Inguinal Lymphadenectomy (VEIL) in patients with penile cancer

ABSTRACT Objective: To report outcomes from the largest multicenter series of penile cancer patients undergoing video endoscopic inguinal lymphadenectomy (VEIL). Materials and Methods: Retrospective multicenter analysis. Authors of 21 centers from the Penile Cancer Collaborative Coalition-Latin America (PeC-LA) were included. All centers performed the procedure following the same previously described standardized technique. Inclusion criteria included penile cancer patients with no palpable lymph nodes and intermediate/high-risk disease and those with non-fixed palpable lymph nodes less than 4 cm in diameter. Categorical variables are shown as percentages and frequencies whereas continuous variables as mean and range. Results: From 2006 to 2020, 210 VEIL procedures were performed in 105 patients. Mean age was 58 (45-68) years old. Mean operative time was 90 minutes (60-120). Mean lymph node yield was 10 nodes (6-16). Complication rate was 15.7%, including severe complications in 1.9% of procedures. Lymphatic and skin complications were noted in 8.6 and 4.8% of patients, respectively. Histopathological analysis revealed lymph node involvement in 26.7% of patients with non-palpable nodes. Inguinal recurrence was observed in 2.8% of patients. 10y- overall survival was 74.2% and 10-y cancer specific survival was 84.8%. CSS for pN0, pN1, pN2 and pN3 were 100%, 82.4%, 72.7% and 9.1%, respectively. Conclusion: VEIL seems to offer appropriate long term oncological control with minimal morbidity. In the absence of non-invasive stratification measures such as dynamic sentinel node biopsy, VEIL emerged as the alternative for the management of non-bulky lymph nodes in penile cancer.

Promoting the activity of a receptor tyrosine phosphatase with a novel pH-responsive transmembrane agonist inhibits cancer-associated phenotypes.

Cell signaling by receptor protein tyrosine kinases (RTKs) is tightly controlled by the counterbalancing actions of receptor protein tyrosine phosphatases (RPTPs). Due to their role in attenuating the signal-initiating potency of RTKs, RPTPs have long been viewed as therapeutic targets. However, the development of activators of RPTPs has remained limited. We previously reported that the homodimerization of a representative member of the RPTP family (protein tyrosine phosphatase receptor J or PTPRJ) is regulated by specific transmembrane (TM) residues. Disrupting this interaction by single point mutations promotes PTPRJ access to its RTK substrates (e.g., EGFR and FLT3), reduces RTK's phosphorylation and downstream signaling, and ultimately antagonizes RTK-driven cell phenotypes. Here, we designed and tested a series of first-in-class pH-responsive TM peptide agonists of PTPRJ that are soluble in aqueous solution but insert as a helical TM domain in lipid membranes when the pH is lowered to match that of the acidic microenvironment of tumors. The most promising peptide reduced EGFR's phosphorylation and inhibited cancer cell EGFR-driven migration and proliferation, similar to the PTPRJ's TM point mutations. Developing tumor-selective and TM-targeting peptide binders of critical RPTPs could afford a potentially transformative approach to studying RPTP's selectivity mechanism without requiring less specific inhibitors and represent a novel class of therapeutics against RTK-driven cancers.

Urine shedding patterns of pathogenic Leptospira spp. in dairy cows.

Pathogenic Leptospira spp. are zoonotic bacteria that infect wild and domestic animals. Humans contract leptospirosis directly through contact with infected animals or indirectly from contaminated water or soil. In mammalian reservoirs, the pathogen can colonize renal tubules for lengthy periods and persistently contaminate the environment through urine. Cattle have been reported to shed several serovars; with Hardjo the most common serovar found in cattle. Without clinical manifestations, the infection can spread within a herd, impairing productivity, and putting workers like farmers, abattoir operators and veterinarians at risk. The dynamics of pathogenic Leptospira shedding was studied in six dairy herds in southern Chile. Various intermittent urine shedding patterns were found, with elimination periods between 79 and 259 days and bacterial loads ranging from 3 × 104 to 4.4 × 104 bacteria/mL. The current study was the first to assess the various urine shedding patterns and loads of pathogenic leptospires shed through urine of naturally-infected dairy cows. In addition, the study suggests that vaccination does not prevent cattle infection, although it influences loads of pathogenic leptospires excreted in urine. Our study provides a great awareness of asymptomatic animal carriers in an endemic area and will contribute to improving disease control and designing better prevention strategies.

Histidine Protonation and Conformational Switching in Diphtheria Toxin Translocation Domain.

Protonation of key histidine residues has been long implicated in the acid-mediated cellular action of the diphtheria toxin translocation (T-) domain, responsible for the delivery of the catalytic domain into the cell. Here, we use a combination of computational (constant-pH Molecular Dynamics simulations) and experimental (NMR, circular dichroism, and fluorescence spectroscopy along with the X-ray crystallography) approaches to characterize the initial stages of conformational change happening in solution in the wild-type T-domain and in the H223Q/H257Q double mutant. This replacement suppresses the acid-induced transition, resulting in the retention of a more stable protein structure in solutions at pH 5.5 and, consequently, in reduced membrane-disrupting activity. Here, for the first time, we report the pKa values of the histidine residues of the T-domain, measured by NMR-monitored pH titrations. Most peaks in the histidine side chain spectral region are titrated with pKas ranging from 6.2 to 6.8. However, the two most up-field peaks display little change down to pH 6, which is a limiting pH for this protein in solution at concentrations required for NMR. These peaks are absent in the double mutant, suggesting they belong to H223 and H257. The constant-pH simulations indicate that for the T-domain in solution, the pKa values for histidine residues range from 3.0 to 6.5, with those most difficult to protonate being H251 and H257. Taken together, our experimental and computational data demonstrate that previously suggested cooperative protonation of all six histidines in the T-domain does not occur.

Pielonefritis xantogranulomatosa: un reto actual para la laparoscopia.

OBJECTIVE: To present the results of our case series on laparoscopic nephrectomy in xanthogranulomatous pyelonephritis (XGP). METHODS: A retrospective study was conducted that included 143 patients treated with laparoscopic nephrectomy for non-functioning kidney, of whom 15 had XGP, within the time frame of 2011 to 2019. The demographic and clinical data were collected, along with the intraoperative results, complications, and days of hospital stay. RESULTS: Transperitoneal laparoscopic nephrectomy was successfully performed on 15 patients with XGP, with no need for conversion. Mean intraoperative time was 124.4 minutes (range 70-240) and intraoperative blood loss was 148.5 ml (range 30-550), with no blood transfusion required. No intraoperative complications occurred but there was one postoperative complication (6.6%), classified as Clavien-Dindo I (surgical wound infection). Mean hospital stay was 2.85 days (range 2-7). CONCLUSIONS: Nephrectomy is the definitive management for XGP, and the laparoscopic approach should be considered a treatment modality, despite the fact that the pathology involves a severe chronic inflammatory process. Its benefits are reduced surgery duration, less blood loss, a lower complication rate, and fewer days of hospital stay, when performed by a skilled and experienced surgeon.

OBJETIVO: Presentar los resultados de nuestra serie de nefrectomía laparoscópica en pielonefritis xantogranulomatosa (PXG). MÉTODO: Se realizó un estudio retrospectivo que incluyó 143 pacientes tratados con nefrectomía laparoscópica por exclusión renal, de los cuales 15 fueron por PXG, en el periodo comprendido de 2011 a 2019. Se recolectaron datos demográficos y clínicos, resultados transoperatorios, complicaciones y días de estancia hospitalaria. RESULTADOS: Se realizó nefrectomía laparoscópica transperitoneal de forma exitosa en 15 pacientes con PXG, sin necesidad de conversión. El tiempo transoperatorio promedio fue de 124.4 minutos (rango: 70-240). El sangrado transoperatorio fue de 148.5 ml (rango: 30-550), sin requerimiento de transfusión sanguínea. No se reportaron complicaciones transoperatorias; se presentó una complicación en el posoperatorio (6.6%) clasificada como Clavien-Dindo I (infección de la herida quirúrgica). La estancia hospitalaria promedio fue de 2.85 días (rango: 2-7). CONCLUSIONES: El manejo definitivo de la PXG es la nefrectomía, y el abordaje laparoscópico debe ser considerado como una modalidad de tratamiento a pesar de ser una patología que presenta un proceso inflamatorio grave y crónico, obteniéndose beneficios como disminución en el tiempo quirúrgico, menor sangrado, menor tasa de complicaciones y menos días de estancia hospitalaria cuando es realizado por un cirujano experimentado.

Long-term oncological and surgical outcomes after Video Endoscopic Inguinal Lymphadenectomy (VEIL) in patients with penile cancer.

OBJECTIVE: To report outcomes from the largest multicenter series of penile cancer patients undergoing video endoscopic inguinal lymphadenectomy (VEIL). MATERIALS AND METHODS: Retrospective multicenter analysis. Authors of 21 centers from the Penile Cancer Collaborative Coalition-Latin America (PeC-LA) were included. All centers performed the procedure following the same previously described standardized technique. Inclusion criteria included penile cancer patients with no palpable lymph nodes and intermediate/high-risk disease and those with non-fixed palpable lymph nodes less than 4 cm in diameter. Categorical variables are shown as percentages and frequencies whereas continuous variables as mean and range. RESULTS: From 2006 to 2020, 210 VEIL procedures were performed in 105 patients. Mean age was 58 (45-68) years old. Mean operative time was 90 minutes (60-120). Mean lymph node yield was 10 nodes (6-16). Complication rate was 15.7%, including severe complications in 1.9% of procedures. Lymphatic and skin complications were noted in 8.6 and 4.8% of patients, respectively. Histopathological analysis revealed lymph node involvement in 26.7% of patients with non-palpable nodes. Inguinal recurrence was observed in 2.8% of patients. 10y- overall survival was 74.2% and 10-y cancer specific survival was 84.8%. CSS for pN0, pN1, pN2 and pN3 were 100%, 82.4%, 72.7% and 9.1%, respectively. CONCLUSION: VEIL seems to offer appropriate long term oncological control with minimal morbidity. In the absence of non-invasive stratification measures such as dynamic sentinel node biopsy, VEIL emerged as the alternative for the management of non-bulky lymph nodes in penile cancer.

Ca2+ and Mg2+ Influence the Thermodynamics of Peptide-Membrane Interactions.

Accurate quantitative estimates of protein-membrane interactions are critical to studies of membrane proteins. Here, we demonstrate that thermodynamic analyses based on current hydropathy scales do not account for the significant and experimentally determined effects that Ca2+ or Mg2+ have on protein-membrane interactions. We examined distinct modes of interaction (interfacial partitioning and folding and transmembrane insertion) by studying three highly divergent peptides: Bid-BH3 (derived from apoptotic regulator Bid), peripherin-2-derived prph2-CTER, and the cancer-targeting pH-Low-Insertion-Peptide (pHLIP). Fluorescence experiments demonstrate that adding 1-2 mM of divalent cations led to a substantially more favorable bilayer partitioning and insertion, with free energy differences of 5-15 kcal/mol.

Ca2+ -dependent interactions between lipids and the tumor-targeting peptide pHLIP.

Cancerous tissues undergo extensive changes to their cellular environments that differentiate them from healthy tissues. These changes include changes in extracellular pH and Ca2+ concentrations, and the exposure of phosphatidylserine (PS) to the extracellular environment, which can modulate the interaction of peptides and proteins with the plasma membrane. Deciphering the molecular mechanisms of such interactions is critical for advancing the knowledge-based design of cancer-targeting molecular tools, such as pH-low insertion peptide (pHLIP). Here, we explore the effects of PS, Ca2+ , and peptide protonation state on the interactions of pHLIP with lipid membranes. Cellular studies demonstrate that exposed PS on the plasma membrane promotes pHLIP targeting. The magnitude of this effect is dependent on extracellular Ca2+ concentration, indicating that divalent cations play an important role in pHLIP targeting in vivo. The targeting mechanism is further explored with a combination of fluorescence and circular dichroism experiments in model membranes and microsecond-timescale all-atom molecular dynamics simulations. Our results demonstrate that Ca2+ is engaged in coupling peptide-lipid interactions in the unprotonated transmembrane conformation of pHLIP. The simulations reveal that while the pH-induced insertion leads to a strong depletion of PS around pHLIP, the Ca2+ -induced insertion has the opposite effect. Thus, extracellular levels of Ca2+ are crucial to linking cellular changes in membrane lipid composition with the selective targeting and insertion of pHLIP. The characterized Ca2+ -dependent coupling between pHLIP sidechains and PS provides atomistic insights into the general mechanism for lipid-coupled regulation of protein-membrane insertion by divalent cations.

Oncological and functional results after robot-assisted radical prostatectomy in high-risk prostate cancer patients.

BACKGROUND: Pentafecta is currently the standard in the comprehensive evaluation of patients undergoing radical prostatectomy, the objective of this study is the evaluation of oncological and functional outcomes in patients with prostate cancer of high risk undergoing robot-assisted radical prostatectomy. METHOD: Descriptive, retrospective study of 20 cases with a diagnosis of high-risk prostate cancer. The high-risk group is composed of a prostate-specific antigen equal or greater than 20 ng/mL, Gleason score equal or greater than 8, or clinical stages T2/T3 treated with robotic approach. RESULTS: Biochemical control was achieved from the first six weeks after the surgical event. 75% (n = 15) had negative surgical margins. 100% of the patients (n = 20) presented urinary continence immediately after removal of the urinary catheter. Erectile function was preserved at 3, 6 and 12 months in 100% of the patients who underwent neuropreservation but with use of an PDE inhibitor. (n = 5). Complications were reported in 10% (Clavien-Dindo I-II). CONCLUSIONS: Robot-assisted radical prostatectomy in patients with high-risk prostate cancer is considered an appropriate treatment option in selected patients. A different experimental design is needed to define the advantages or disadvantages of this approach, as well as to determine its role and application in clinical practice.

ANTECEDENTES: Pentafecta es el estándar en la evaluación integral de los pacientes sometidos a prostatectomía radical. El objetivo de este estudio es evaluar y describir los desenlaces oncológicos y funcionales en pacientes con cáncer de próstata de alto riesgo sometidos a prostatectomía radical asistida por robot. MÉTODO: Estudio descriptivo, retrospectivo, de 20 pacientes con diagnóstico de cáncer de próstata de alto riesgo. El grupo de alto riesgo se compone por pacientes con antígeno prostático específico mayo o igual a 20 ng/ml, reporte histopatológico con Gleason mayor o igual a 8 y/o estadios clínicos T2/T3 tratados con abordaje robótico. RESULTADOS: El control bioquímico se alcanzó a partir de las primeras 6 semanas posterior al evento quirúrgico. El 75% (n = 15) presentaron márgenes quirúrgicos negativos. El 100% de los pacientes (n = 20) presentaron continencia urinaria inmediatamente después del retiro de la sonda vesical. La función eréctil se conservó a 3, 6 y 12 meses en el 100% de los pacientes a los que se realizó neuropreservación, pero con uso de inhibidor de la fosfodiesterasa (n = 5). Se reportaron complicaciones en el 10% de los casos (Clavien-Dindo I-II). CONCLUSIONES: La prostatectomía radical asistida por robot en pacientes con cáncer de próstata de alto riesgo se considera una opción de tratamiento adecuada en casos seleccionados. Se necesita un diseño experimental distinto para definir las ventajas o desventajas de este abordaje, así como determinar su papel y aplicación en la práctica clínica.

Advantages of Quantitative Analysis of Depth-Dependent Fluorescence Quenching: Case Study of BAX.

Dynamic disorder of the lipid bilayer presents a challenge for establishing structure-function relationships in membrane proteins, especially to those that insert by refolding from soluble states, e.g., bacterial toxins and Bcl-2 apoptotic regulators. Because many high-resolution structural techniques cannot be easily applied to such systems, methods like depth-dependent fluorescence quenching gained prominence. Over three decades ago, Prof. Erwin London and his co-workers revolutionized the studies of membrane protein insertion by introducing a quantitative approach to the analysis of membrane quenching data and inspired many researchers to continue this work. Here, we illustrate how the application of the quantitative analysis yields new insights into previously published results. We have used the method of distribution analysis (DA) to calculate the precise immersion depth of NBD fluorophores selectively attached to various single-cysteine mutants of the apoptotic factor BAX from quenching data obtained with a series of spin-labeled lipids. The original qualitative analysis interpreted the higher quenching determined for shallower probes in positions flanking the helix 9 of BAX as evidence of a transmembrane helix 9 topology. The quantitative DA, however, revealed that a transmembrane topology of helix 9 of BAX is unlikely, as it would require labeling sites that are only 15 residues apart in a helical conformation to be separated by a transverse distance of over 45 Å.

Pathogenic Leptospira spp. Seroprevalence and Herd-Level Risk Factors Associated with Chilean Dairy Cattle.

Leptospirosis is a ubiquitous distributed zoonotic infectious disease present in wild and domestic animals. This study aimed to estimate within-herd and herd-level seroprevalence against pathogenic Leptospira spp. in dairy cows from southern Chile and identify risk factors associated with the herd-level status. We used a multi-stage strategy combined with a stratified sample strategy for randomly sampling 147 herds and 4876 lactating cows. We considered as infected a herd with at least one positive reactor to MAT. In addition, an epidemiological survey was applied to the herd's owners and a logistic regression (LR) model was constructed to analyze it. The overall within-herd prevalence was 5.9% (95% CI 4.9-6.8), the overall herd-level prevalence was 42.2% (95% CI 9.2-47.9), and there was variation in both between different herd sizes. L. borgpetersenii serovars Hardjo and Tarassovi and L. interrogans serovar Pomona were the more frequent serovars in non-vaccinated herds. A factor that decreases the risk of a farm being infected was Leptospira vaccine usage (OR = 0.04; 95% CI = 0.02-0.11), and variables that increase risk were using bulls for mating (OR = 3.43; 95% CI = 1.1-10.1) and continuous calving distribution (OR = 3.4; 95% CI = 1.3-8.8). The study's results will contribute to unravelling the infection burden in the main dairy area of the country and designing control strategies.

Lipids modulate the BH3-independent membrane targeting and activation of BAX and Bcl-xL.

Regulation of apoptosis is tightly linked with the targeting of numerous Bcl-2 proteins to the mitochondrial outer membrane (MOM), where their activation or inhibition dictates cell death or survival. According to the traditional view of apoptotic regulation, BH3-effector proteins are indispensable for the cytosol-to-MOM targeting and activation of proapoptotic and antiapoptotic members of the Bcl-2 protein family. This view is challenged by recent studies showing that these processes can occur in cells lacking BH3 effectors by as yet to be determined mechanism(s). Here, we exploit a model membrane system that recapitulates key features of MOM to demonstrate that the proapoptotic Bcl-2 protein BAX and antiapoptotic Bcl-xL have an inherent ability to interact with membranes in the absence of BH3 effectors, but only in the presence of cellular concentrations of Mg2+/Ca2+ Under these conditions, BAX and Bcl-xL are selectively targeted to membranes, refolded, and activated in the presence of anionic lipids especially the mitochondrial-specific lipid cardiolipin. These results provide a mechanistic explanation for the mitochondrial targeting and activation of Bcl-2 proteins in cells lacking BH3 effectors. At cytosolic Mg2+ levels, the BH3-independent activation of BAX could provide localized amplification of apoptotic signaling at regions enriched in cardiolipin (e.g., contact sites between MOM and mitochondrial inner membrane). Increases in MOM cardiolipin, as well as cytosolic [Ca2+] during apoptosis could further contribute to its MOM targeting and activity. Meanwhile, the BH3-independent targeting and activation of Bcl-xL to the MOM is expected to counter the action of proapoptotic BAX, thereby preventing premature commitment to apoptosis.

Effects of Cardiolipin on the Conformational Dynamics of Membrane-Anchored Bcl-xL.

The anti-apoptotic protein Bcl-xL regulates apoptosis by preventing the permeation of the mitochondrial outer membrane by pro-apoptotic pore-forming proteins, which release apoptotic factors into the cytosol that ultimately lead to cell death. Two different membrane-integrated Bcl-xL constructs have been identified: a membrane-anchored and a membrane-inserted conformation. Here, we use molecular dynamics simulations to study the effect of the mitochondrial specific lipid cardiolipin and the protein protonation state on the conformational dynamics of membrane-anchored Bcl-xL. The analysis reveals that the protonation state of the protein and cardiolipin content of the membrane modulate the orientation of the soluble head region (helices α1 through α7) and hence the exposure of its BH3-binding groove, which is required for its interaction with pro-apoptotic proteins.

Spectroscopic evidence of tetanus toxin translocation domain bilayer-induced refolding and insertion.

Tetanus neurotoxin (TeNT) is an A-B toxin with three functional domains: endopeptidase, translocation (HCT), and receptor binding. Endosomal acidification triggers HCT to interact with and insert into the membrane, translocating the endopeptidase across the bilayer. Although the function of HCT is well defined, the mechanism by which it accomplishes this task is unknown. To gain insight into the HCT membrane interaction on both local and global scales, we utilized an isolated, beltless HCT variant (bHCT), which retained the ability to release potassium ions from vesicles. To examine which bHCT residues interact with the membrane, we widely sampled the surface of bHCT using 47 single-cysteine variants labeled with the environmentally sensitive fluorophore NBD. At neutral pH, no interaction was observed for any variant. In contrast, all NBD-labeled positions reported environmental change in the presence of acidic pH and membranes containing anionic lipids. We then examined the conformation of inserted bHCT using circular dichroism and intrinsic fluorescence. Upon entering the membrane, bHCT retained predominantly α-helical secondary structure, whereas the tertiary structure exhibited substantial refolding. The use of lipid-attached quenchers revealed that at least one of the three tryptophan residues penetrated deep into the hydrocarbon core of the membrane, suggesting formation of a bHCT transmembrane conformation. The possible conformational topology was further explored with the hydropathy analysis webtool MPEx, which identified a large, potential α-helical transmembrane region. Altogether, the spectroscopic evidence supports a model in which, upon acidification, the majority of TeNT bHCT entered the membrane with a concurrent change in tertiary structure.

Experiencia de la plastia laparoscópica de uréter retrocavo en el Hospital General de México Dr. Eduardo Liceaga.

INTRODUCCIÓN: El uréter retrocavo es una anomalía congénita rara que requiere manejo quirúrgico. OBJETIVO: Reportar los resultados en el manejo laparoscópico para uréter retrocavo y hacer una revisión bibliográfica. MÉTODO: Estudio retrospectivo, descriptivo, transversal, en pacientes con diagnóstico de uréter retrocavo que fueron sometidos a plastia laparoscópica de uréter retrocavo. RESULTADOS: Cuatro pacientes sometidos a plastia laparoscópica por diagnóstico de uréter retrocavo, 1 hombre y 3 mujeres, con una media de edad de 40.7 años. La media del tiempo operatorio fue de 138.2 minutos. La pérdida de sangre cuantificada transoperatoria media fue de 23.7 ml. Ningún paciente presentó complicaciones transoperatorias ni posoperatorias. Los pacientes permanecieron hospitalizados hasta su egreso una media de 2.5 días. Todos los pacientes presentaron mejoría de su sintomatología. CONCLUSIONES: El uréter retrocavo es una condición rara y aún no existe un consenso sobre su diagnóstico, tratamiento y seguimiento. El manejo quirúrgico laparoscópico es una opción para el tratamiento de estos pacientes. INTRODUCTION: The retrocave ureter is a rare congenital anomaly that requires surgical management. OBJECTIVE: Report the results in laparoscopic management for retrocave ureter and literature review. METHOD: Retrospective, descriptive, cross-sectional study in patients with a diagnosis of retrocave ureter who were sometimes a laparoscopic retrocave ureter. RESULTS: Four patients sometimes underwent laparoscopic plasty for diagnosis of retrocave ureter, 1 man and 3 women, with a mean age of 40.7 years. The mean operative time was 138.2 minutes. The mean intraoperative quantified blood loss was 23.7 ml. No patient presented transoperative or postoperative complications. The patients remained hospitalized until their progress with an average of 2.5 days. All patients visualize improvement in their symptoms. CONCLUSION: The retrocave ureter is a rare condition and there is still no consensus on its diagnosis, treatment and follow-up. Laparoscopic surgical management is an option for the treatment of these patients.

Adrenal cyst: our experience in its laparoscopic management.

ANTECEDENTES: Los quistes suprarrenales son una afección rara. Su diagnóstico y su tratamiento son un desafío debido a la escasa información, lo que genera incertidumbre respecto al mejor manejo. CASOS CLÍNICOS: Presentamos tres casos de quistes suprarrenales que recibieron tratamiento de mínima invasión con cirugía laparoscópica, sin presentar complicaciones y con una evolución favorable. DISCUSIÓN: Las nuevas técnicas quirúrgicas de mínima invasión ofrecen una oportunidad terapéutica que permite preservar estructuras y obtener material necesario para su diagnóstico histopatológico, así como la resolución de la sintomatología. BACKGROUND: Adrenal cysts are a rare entity; their diagnosis and treatment are challenging due to the lack of information, generating uncertainty regarding the best management. CASE REPORTS: We present three cases of adrenal cysts that received minimally invasive treatment with laparoscopic surgery, without complications and with a favorable evolution. DISCUSSION: The new minimally invasive surgical techniques offer a therapeutic opportunity that allows preserving structures and obtaining the necessary material for histopathological diagnosis, as well as a resolution of the symptoms.

Conformational switching, refolding and membrane insertion of the diphtheria toxin translocation domain.

Diphtheria toxin is among many bacterial toxins that utilize the endosomal pathway of cellular entry, which is ensured by the bridging of the endosomal membrane by the toxin's translocation (T) domain. Endosomal acidification triggers a series of conformational changes of the T-domain, that take place first in aqueous and subsequently in membranous milieu. These rearrangements ultimately result in establishing membrane-inserted conformation(s) and translocation of the catalytic moiety of the toxin into the cytoplasm. We discuss here the strategy for combining site-selective labeling with various spectroscopic methods to characterize structural and thermodynamic aspects of protonation-dependent conformational switching and membrane insertion of the diphtheria toxin T-domain. Among the discussed methods are FRET, FCS and depth-dependent fluorescence quenching with lipid-attached bromine atoms and spin probes. The membrane-insertion pathway of the T-domain contains multiple intermediates and is governed by staggered pH-dependent transitions involving protonation of histidines and acidic residues. Presented data demonstrate that the lipid bilayer plays an active part in T-domain functioning and that the so-called Open-Channel State does not constitute the translocation pathway, but is likely to be a byproduct of the translocation. The spectroscopic approaches presented here are broadly applicable to many other systems of physiological and biomedical interest for which conformational changes can lead to membrane insertion (e.g., other bacterial toxins, host defense peptides, tumor-targeting pHLIP peptides and members of Bcl-2 family of apoptotic regulators).

Expanding MPEx Hydropathy Analysis to Account for Electrostatic Contributions to Protein Interactions with Anionic Membranes.

Hydropathy plots are a crucial tool to guide experimental design, as they generate predictions of protein-membrane interactions and their bilayer topology. The predictions are based on experimentally determined hydrophobicity scales, which provide an estimate for the propensity and stability of these interactions. A significant improvement to the accuracy of hydropathy analyses was provided by the development of the popular Wimley-White interfacial and octanol hydrophobicity scales. These scales have been previously incorporated into the freely available MPEx (Membrane Protein Explorer) online application. Here, we introduce a substantial update to MPEx that allows for the consideration of electrostatic contributions to the bilayer partitioning free energy. This component originates from the Coulombic attraction or repulsion of charges between proteins and membranes. Its inclusion in hydropathy calculations increases the accuracy of hydropathy plot predictions and extends their use to more complex systems (i.e., anionic membranes). We illustrate the application of this analysis to studies on the membrane selectivity of antimicrobial peptides, the membrane partitioning of ion-channel gating modifiers, and the amyloid proteins α-synuclein and Tau, as well as pH-dependent bilayer interactions of diphtheria toxin and apoptotic inhibitor Bcl-xL.