A Gauss's law analysis of redox active adsorbates on semiconductor electrodes: The charging and faradaic currents are not independent.

A detailed framework for modeling and interpreting the data in totality from a cyclic voltammetric measurement of adsorbed redox monolayers on semiconductor electrodes has been developed. A three-layer model consisting of the semiconductor space-charge layer, a surface layer, and an electrolyte layer is presented that articulates the interplay between electrostatic, thermodynamic, and kinetic factors in the electrochemistry of a redox adsorbate on a semiconductor. Expressions are derived that describe the charging and faradaic current densities individually, and an algorithm is demonstrated that allows for the calculation of the total current density in a cyclic voltammetry measurement as a function of changes in the physical properties of the system (e.g., surface recombination, dielectric property of the surface layer, and electrolyte concentration). The most profound point from this analysis is that the faradaic and charging current densities can be coupled. That is, the common assumption that these contributions to the total current are always independent is not accurate. Their interrelation can influence the interpretation of the charge-transfer kinetics under certain experimental conditions. More generally, this work not only fills a long-standing knowledge gap in electrochemistry but also aids practitioners advancing energy conversion/storage strategies based on redox adsorbates on semiconductor electrodes.

A Description of the Faradaic Current in Cyclic Voltammetry of Adsorbed Redox Species on Semiconductor Electrodes.

A framework for interpreting the cyclic voltammetric responses from adsorbed redox monolayers on semiconductor electrodes has been developed. Expressions that describe quantitatively how the rates of the forward and back charge-transfer reactions impact the faradaic current density are presented. The primary insight is an explicit connection between the potential drops across the semiconductor space charge, surface, and electrolyte diffuse layers and the potential dependence of the reaction kinetics. Specifically, the evolution of the voltammetric shapes with experimental variables such as scan rate, standard potential of the redox adsorbate, and semiconductor surface energetics can now be interpreted for information on the operative charge-transfer rate constant and reaction energetics. This model is used to understand the complex dependence of the cathodic and anodic wave shapes for the first redox transition of an asymmetric viologen species adsorbed on n-Si(111). This system exhibited a heterogeneous rate constant of 0.24 s-1 and exhibited features consistent with an overwhelming majority of the applied potential dropping within the semiconductor space charge region. In total, experimentalists now have a visual key on how to interpret the faradaic current in voltammetric data for information on heterogeneous charge-transfer reactions between semiconductor electrodes and molecular adsorbates. The presented approach fills a long-standing knowledge gap in electrochemistry and aids practitioners interested in advancing photoelectrochemical energy conversion/storage strategies.

Combination Therapy With Bortezomib in Renal Medullary Carcinoma: A Case Series.

BACKGROUND: Renal medullary carcinoma (RMC) is a very rare, aggressive neoplasm occurring almost exclusively in adolescents and young adults with sickle cell trait. Given the rare nature of this tumor, accounting for less than 0.5% of all renal carcinomas, most of the published data on therapies is from case reports and small case series, and current treatments are insufficient, with most patients succumbing to their disease in months. We report our experience with a cytotoxic chemotherapy regimen consisting of platinum-based therapy, doxorubicin, and bortezomib. METHODS: Three patients with metastatic RMC at a single institution were treated off-label with a perioperative chemotherapy regimen for 4 cycles of 2 alternating regimens: regimen A consisting of cisplatin, doxorubicin, and bortezomib; regimen B consisting of carboplatin, paclitaxel, and gemcitabine. A radical nephrectomy was performed on all patients. Surveillance imaging was performed on all patients to assess response and disease burden. Patients received up to 12 months of maintenance therapy with everolimus. RESULTS: Three African American patients - 2 males and 1 female aged 14, 28, and 31 - with sickle cell trait and metastatic disease were treated with this regimen. The median follow-up was 18 months. All had resection of the primary tumor - 2 patients after receiving neoadjuvant therapy, and one patient underwent resection prior to referral. All 3 patients achieved complete responses based on imaging, 2 of which lasted for 12 months, and another is still in remission over 7 years after diagnosis. CONCLUSIONS: This regimen of alternating cycles of platinum-based chemotherapy with bortezomib appeared to be active against RMC and was generally well-tolerated. Given the extremely rare nature of this disease and dismal prognosis, new treatment modalities should be pursued, and whenever possible, patients should be enrolled in a clinical trial. We propose that a multiinstitution clinical trial of this regiment may be warranted.

Very Late Relapse in Pediatric Acute Myeloid Leukemia: A Case Report and Brief Literature Review.

Acute myeloid leukemia (AML) is a heterogenous group of diseases affecting ~500 children in the United States annually. With current therapy, 90% of these children will obtain complete remission. However, 30% to 40% of these patients will relapse, most commonly within the first 3 years. Very late relapses, defined as relapse occurring >5 years after complete remission, are rare, accounting for 1% to 3% of relapses. We describe a patient with AML harboring an AFDN/KMT2A translocation who relapsed 12 years after matched sibling stem cell transplant, provide a brief review of the relevant literature, and describe proposed mechanisms to explain very late relapse AML.

T3 versus T4a staging challenges in deeply invasive colonic adenocarcinomas and correlation with clinical outcomes.

Despite the latest 8th edition American Joint Committee on Cancer Staging Manual guidelines, disagreement still exists among pathologists regarding staging deeply invasive colonic adenocarcinomas ≤1 mm to the serosal surface. In this retrospective study, 151 untreated colonic adenocarcinomas staged initially as either pT3 or pT4a and with available 5-year follow-up data were retrieved and re-categorized: Group 1 (38 cases): pT4a with tumor at the serosa; Group 2 (49 cases): tumor ≤1 mm from the serosa, with intervening reactive fibrosis (40/49) or inflammation (9/49); Group 3 (64 cases): pT3 tumor >1 mm from the serosa. Clinical outcomes were analyzed. Groups 1 and 2 tumors showed significantly lower 5-year recurrence-free survival and lower overall survival rates (log-rank p < 0.001 for both), when compared with Group 3 tumors. Even after adjusting for adjuvant therapy and nodal metastases, the proportional hazards ratios for the risk of death (p < 0.001) and risk of recurrence (p = 0.005) showed significantly higher risk in Groups 1 and 2 compared with Group 3. The synchronous nodal (p = 0.012) and metachronous distant metastases (p = 0.004) were also significantly more in Groups 1 and 2 versus Group 3. Colonic adenocarcinomas ≤1 mm from the serosal surface behaved more akin to "bona fide" pT4a tumors at the serosal surface in our study with regards to clinical outcomes. We recommend these tumors be staged as pT4a rather than pT3, as supported by outcome data in our study. We hope this will also ensure reproducibility and consistency in staging these tumors across institutions.

Effect of Covalent Surface Functionalization of Si on the Activity of Trifluoromethanesulfonic Anhydride for Suppressing Surface Recombination.

An examination of the efficacy of combining physisorbed and chemisorbed passivation strategies on crystalline Si has been performed. This report compares the influence of a linear alkyl adsorbate tethered by either a Si-C or Si-Si linkage, prepared by reaction of Si(111) with organometallic Grignard reagents or organosilanes, respectively. These modified surfaces are first analyzed and compared by IR and X-ray photoelectron spectroscopies. Their behavior toward a known potent physisorbate, trifluoromethanesulfonic anhydride (Tf2O), is then examined. Microwave photoconductivity measurements were obtained which indicate that, while Tf2O shows a beneficial lowering of surface recombination on both surface types initially, only surfaces featuring Si-C linkages exhibit long-lasting suppressed surface recombination. The data for Grignard-treated Si after exposure to Tf2O in fact represent the longest known report of surface recombination suppression by a physisorbate. Conversely, the data for the Si surfaces prepared by dehydrogenative coupling suggest that these passivating groups themselves introduce defect states that cannot be ameliorated by Tf2O physisorption.

Ruthenium (II) and Iridium (III) Complexes of N-Heterocyclic Carbene and Pyridinol Derived Bidentate Chelates: Synthesis, Characterization, and Reactivity.

We report the synthesis and characterization of new ruthenium(II) and iridium(III) complexes of a new bidentate chelate, NHCR'-pyOR (OR = OMe, OtBu, OH and R' = Me, Et). Synthesis and characterization studies were done on the following compounds: four ligand precursors (1-4); two silver complexes of these NHCR'-pyOR ligands (5-7); six ruthenium complexes of the type [η6-(p-cymene)Ru(NHCR'-pyOR)Cl]X with R' = Me, Et and R = Me, tBu, H and X = OTf-, PF6- and PO2F2- (8-13); and two iridium complexes, [Cp*Ir(NHCMe-pyOtBu)Cl]PF6 (14) and [Cp*Ir(NHCMe-pyOH)Cl]PO2F2 (15). The complexes are air stable and were isolated in moderate yield. However, for the PF6- salts, hydrolysis of the PF6- counter anion to PO2F2- during t-butyl ether deprotection was observed. Most of the complexes were characterized by 1H and 13C-NMR, MS, IR, and X-ray diffraction. The ruthenium complexes [η6-(p-cymene)Ru(NHCMe-pyOR)Cl]OTf (R = Me (8) and tBu (9)) were tested for their ability to accelerate CO2 hydrogenation and formic acid dehydrogenation. However, our studies show that the complexes transform during the reaction and these complexes are best thought of as pre-catalysts.

Iridium and Ruthenium Complexes of N-Heterocyclic Carbene- and Pyridinol-Derived Chelates as Catalysts for Aqueous Carbon Dioxide Hydrogenation and Formic Acid Dehydrogenation: The Role of the Alkali Metal.

Hydrogenation reactions can be used to store energy in chemical bonds, and if these reactions are reversible, that energy can be released on demand. Some of the most effective transition metal catalysts for CO2 hydrogenation have featured pyridin-2-ol-based ligands (e.g., 6,6'-dihydroxybipyridine (6,6'-dhbp)) for both their proton-responsive features and for metal-ligand bifunctional catalysis. We aimed to compare bidentate pyridin-2-ol based ligands with a new scaffold featuring an N-heterocyclic carbene (NHC) bound to pyridin-2-ol. Toward this aim, we have synthesized a series of [Cp*Ir(NHC-pyOR)Cl]OTf complexes where R = t Bu (1), H (2), or Me (3). For comparison, we tested analogous bipy-derived iridium complexes as catalysts, specifically [Cp*Ir(6,6'-dxbp)Cl]OTf, where x = hydroxy (4Ir ) or methoxy (5Ir ); 4Ir was reported previously, but 5Ir is new. The analogous ruthenium complexes were also tested using [(η6-cymene)Ru(6,6'-dxbp)Cl]OTf, where x = hydroxy (4Ru ) or methoxy (5Ru ); 4Ru and 5Ru were both reported previously. All new complexes were fully characterized by spectroscopic and analytical methods and by single-crystal X-ray diffraction for 1, 2, 3, 5Ir , and for two [Ag(NHC-pyOR)2]OTf complexes 6 (R = t Bu) and 7 (R = Me). The aqueous catalytic studies of both CO2 hydrogenation and formic acid dehydrogenation were performed with catalysts 1-5. In general, NHC-pyOR complexes 1-3 were modest precatalysts for both reactions. NHC complexes 1-3 all underwent transformations under basic CO2 hydrogenation conditions, and for 3, we trapped a product of its transformation, 3SP , which we characterized crystallographically. For CO2 hydrogenation with base and dxbp-based catalysts, we observed that x = hydroxy (4Ir ) is 5-8 times more active than x = methoxy (5Ir ). Notably, ruthenium complex 4Ru showed 95% of the activity of 4Ir . For formic acid dehydrogenation, the trends were quite different with catalytic activity showing 4Ir ≫ 4Ru and 4Ir ≈ 5Ir . Secondary coordination sphere effects are important under basic hydrogenation conditions where the OH groups of 6,6'-dhbp are deprotonated and alkali metals can bind and help to activate CO2. Computational DFT studies have confirmed these trends and have been used to study the mechanisms of both CO2 hydrogenation and formic acid dehydrogenation.

Lichen sclerosus: a potpourri of misdiagnosed cases based on atypical clinical presentations.

OBJECTIVE: Lichen sclerosus (LS) is a chronic progressive inflammatory autoimmune-induced disease that primarily affects the epidermis and dermis of the external genital-anal region. Intense and recalcitrant pruritus is the hallmark of LS. Physical exam reveals thinning, hyperkeratosis, and parchment-like appearance. However, the classic symptom and signs of LS may not always be present and patients may be asymptomatic for pruritus. Hence, we describe 15 misdiagnosed cases with atypical clinical presentations. We believe that the absence of pruritus contributed to their initial misdiagnosis. The purpose of this paper is to increase awareness of atypical presentations of LS. METHODS: Data base review of de-identified clinical case pictures was performed. All patients had histopathology-confirmed diagnoses of LS. The data base file contains 800 cases of vulvovaginal disorders. The Institutional Review Board (IRB) considered that searching a de-identified data base of pictures did not require IRB approval. RESULTS: We identified 15 different atypical clinical cases. Patient ages were 18-75 years old. These patients were asymptomatic for pruritus and were misdiagnosed before they presented to the vulvovaginal specialized clinic. CONCLUSION: Fifteen patients asymptomatic for pruritus with histopathology-confirmed diagnosis of LS were identified. They illustrate atypical clinical presentations that LS may have.

Lymphocyte-Predominant Hodgkin's Disease in Children: A Case Study and Review of the Literature.

A three-year-old boy presented with an enlarging neck mass. Biopsy demonstrated IgD-positive nodular lymphocyte-predominant Hodgkin lymphoma (NLPHL), which was staged as IIa. The patient received cyclophosphamide, doxorubicin, vincristine, and prednisone (CHOP) with rituximab and had excellent results. NLPHL is a relatively rare disease that is biologically distinct from classic Hodgkin lymphoma (cHL). NLPHL is a B-cell malignancy likely of germinal center origin that has an overall good prognosis and favorable response to treatment. Unlike cHL, NLPHL is ubiquitously CD20-positive. Recent evidence supports the efficacy of targeted anti-CD20 therapy in NLPHL, though prospective data is limited. This case demonstrates several unique features of NLPHL and further supports the use of rituximab in front-line therapy. The clinical characteristics among patients at various ages are discussed with a special focus on the IgD-positive subtype. A thorough literature search demonstrates this to be the youngest patient with NLPHL yet described.

Arp2/3 inhibition induces amoeboid-like protrusions in MCF10A epithelial cells by reduced cytoskeletal-membrane coupling and focal adhesion assembly.

Here we demonstrate that Arp2/3 regulates a transition between mesenchymal and amoeboid protrusions in MCF10A epithelial cells. Using genetic and pharmacological means, we first show Arp2/3 inhibition impairs directed cell migration. Arp2/3 inhibition results in a dramatically impaired cell adhesion, causing deficient cell attachment and spreading to ECM as well as an 8-fold decrease in nascent adhesion assembly at the leading edge. While Arp2/3 does not play a significant role in myosin-dependent adhesion growth, mature focal adhesions undergo large scale movements against the ECM suggesting reduced coupling to the ECM. Cell edge protrusions occur at similar rates when Arp2/3 is inhibited but their morphology is dramatically altered. Persistent lamellipodia are abrogated and we observe a markedly increased incidence of blebbing and unstable pseuodopods. Micropipette-aspiration assays indicate that Arp2/3-inhibited cells have a weak coupling between the cell cortex and the plasma membrane, and suggest a potential mechanism for increased pseudopod and bleb formation. Pseudopods are not sensitive to reduced in formin or myosin II activity. Collectively, these results indicate that Arp2/3 is not necessary for rapid protrusion of the cell edge but plays a crucial role in assembling focal adhesions required for its stabilization.

Esplenectomía parcial con autosuturadora / Splenectomy partial with autosuturated

La descripción de la infección fulminante pos-esplenectomía, en 1952, permitió considerar el manejo conservador de las lesiones esplénicas y la esplenectomía parcial representa una alternativa importante dentro de la cirugía preservadora del bazo. Desde principio de los 80, se describe la utilización de máquinas de autosutura en parénquima esplénico para diversas lesiones. El presente trabajo prospectivo demostró la efectividad del procedimiento de esplenectomía parcial en perros mediante el uso de las máquinas autosuturadas de 90 mm con dimensiones de cierre de 4.0 x 4.5 mm, y evaluó las complicaciones derivadas de su uso. Se realizan esplenectomías parciales en 20 perros de experimentación, distribuidos en dos grupos de 10 animales cada uno. En el grupo A por técnica convencional y en el grupo B con máquina autosuturadora. Se registraron las complicaciones intra y posoperatorias derivadas del procedimiento. Instituto de Cirugía Experimental Escuela de Medicina Luis Razetti, Universidad Central de Venezuela. Se evidenció menor promedio de tiempo operatorio (3 min) en el grupo de esplenectomías parciales con máquinas autosuturadas con respecto al grupo de esplenectomías parciales por técnica convencional, siendo esta diferencia estadísticamente significativa. La única complicación que se presentó en ambos grupos fue el sangramiento intraoperatorio del parénquima esplénico seccionado, no estableciéndose diferencia estadísticamente significativas entre los mismos. La esplenectomía parcial con máquinas autosuturadas es un método seguro y rápido como alternativa en la cirugía esplénica conservadora

Adenocarcinoma de trompa de falopio: presentación de un caso / Fallopian tube adenocarcinoma: presentation of one case

Informar de un caso clínico quirúrgico infrecuente. Descripción del hallazgo de un adenocarcinoma de la trompa de Falopio en una paciente de 75 años, quien consultó por sangrado genital. Estudios pre operatorios sugerían tumor de ovario izquierdo. Hospital "Miguel Pérez Carreño", Servicio de Cirugía II. Durante el acto quirúrgico se encontró un tumor en la trompa izquierda cuya histopatología fue concordante con adenocarcinoma. Hubo de ser reintervenida para estadificación. Los cánceres primarios de las trompas de Falopio son los menos frecuentes del aparato genital femenino y se han relacionado con inflamación tubárica precedente. Generalmente se presentan como masas pélvicas y hemorragia genital en posmenopaúsicas