Direct measurement of single-molecule dynamics and reaction kinetics in confinement using time-resolved transmission electron microscopy.

We report experimental methodologies utilising transmission electron microscopy (TEM) as an imaging tool for reaction kinetics at the single molecule level, in direct space and with spatiotemporal continuity. Using reactions of perchlorocoronene (PCC) in nanotubes of different diameters and at different temperatures, we found a period of molecular movement to precede the intermolecular addition of PCC, with a stronger dependence of the reaction rate on the nanotube diameter, controlling the local environments around molecules, than on the reaction temperature (-175, 23 or 400 °C). Once initiated, polymerisation of PCC follows zero-order reaction kinetics with the observed reaction cross section σobs of 1.13 × 10-9 nm2 (11.3 ± 0.6 barn), determined directly from time-resolved TEM image series acquired with a rate of 100 frames per second. Polymerisation was shown to proceed from a single point, with molecules reacting sequentially, as in a domino effect, due to the strict conformational requirement of the Diels-Alder cycloaddition creating the bottleneck for the reaction. The reaction mechanism was corroborated by correlating structures of reaction intermediates observed in TEM images, with molecular weights measured by using mass spectrometry (MS) when the same reaction was triggered by UV irradiation. The approaches developed in this study bring the imaging of chemical reactions at the single-molecule level closer to traditional concepts of chemistry.

Lymphedematous fibroepithelial polyps of the penis associated with long-term condom catheter use: case report and review of the literature.

Lymphedematous fibroepithelial polyps of the penis are lesions that have only recently been described and are frequently associated with condom catheter use. We report an additional case of lymphedematous fibroepithelial polyps of the penis in association with long-term condom catheter use in a 36-year-old man. Local excision showed large polypoid nodules with compact orthohyperkeratosis and mild acanthosis. The stroma was hypercellular with spindled to stellate fibroblasts and occasional multinucleated cells. Proliferation of small linear to slightly arcuate vessels with some superficial dilatation was a prominent feature. Focal expression of smooth muscle actin and desmin was present in the stroma. Lymphedematous fibroepithelial polyps of the penis are rare lesions with only 11 cases previously reported. We present here an additional example of this entity to highlight the differential diagnosis, the association with condom catheter use and to raise awareness for this unusual diagnosis.

AIRBED: A Simplified Density Functional Theory Model for Physisorption on Surfaces.

Dispersion interactions are commonly included in density functional theory (DFT) calculations through the addition of an empirical correction. In this study, a modification is made to the damping function in DFT-D2 calculations to describe repulsion at small internuclear distances. The resulting Atomic Interactions Represented By Empirical Dispersion (AIRBED) approach is used to model the physisorption of molecules on surfaces such as graphene and hexagonal boron nitride, where the constituent atoms of the surface are no longer required to be included explicitly in the density functional theory calculation but are represented by a point charge to capture electrostatic effects. It is shown that this model can reproduce the structures predicted by full DFT-D2 calculations to a high degree of accuracy. The significant reduction in computational cost allows much larger systems to be studied, including molecular arrays on surfaces and sandwich complexes involving organic molecules between two surface layers.

An 80-year-old man with a ring-enhancing right basal ganglia lesion.

Cerebral phaeohyphomycosis is a rare diagnosis that designates a central nervous system (CNS) infection by dematiaceous fungi. These organisms most commonly cause cutaneous infections in humans, but much less commonly, they cause CNS disease with evidence of neurotropism. We describe here the clinical course and post-mortem findings in a fatal case of cerebral phaeohyphomycosis occurring in an 80-year-old man. He had a long and complex past medical history and approximately 7 weeks prior to his death, he presented to an outside institution with imaging findings reported to be consistent with a cerebrovascular accident. He was treated with thrombolytic therapy and sent to a rehabilitation program. Approximately 2 weeks prior to his death, he was transferred to our institution with worsening chronic heart failure symptoms. Imaging after admission showed a ring-enhancing lesion and the differential diagnosis shifted to include a primary neoplasm vs. an abscess. There was a downward clinical course and neurosurgical biopsy was declined secondary to predicted poor outcome. A full autopsy was performed and confirmed the pre-mortem imaging findings of a cerebral abscess with multiple satellite lesions. The histologic and microbiologic findings were characteristic of cerebral phaeohyphomycosis. Microbiological features and disease characteristics of these organisms as well as incidence and populations affected are also discussed.

Transoral resection of a retropharyngeal myxoma: a case report.

This study was conducted to describe a retropharyngeal myxoma and discuss clinical concerns regarding this pathology and a retropharyngeal site of occurrence. We present a case report and review of literature. A 71-year-old woman presented with mild right neck pressure for 3 weeks. Imaging studies and head neck examination confirmed a 5.3 × 3.1 × 1.0 cm retropharyngeal mass with no communication to the vertebral column but was intimately involved with the pharyngeal mucosa. A transoral fine needle aspiration biopsy suggested a possible spindle cell neoplasm. A presurgical swallowing consultation was obtained. A transoral excision of the tumor was possible with no intraoperative complications. Histopathology was a cellular myxoma. Postoperative dysphagia required swallowing therapy and nasogastric tube feeding for 2 weeks before oral intake was possible. The patient has no evidence of clinical or radiological recurrence more than 1 year after surgical intervention. We present the second case of a myxoma in the retropharynx reported in English literature. Transoral excision was safe, feasible, and cosmetically appealing option in our patient. Additional clinical data are required to valid its safety and utility as an approach to tumors in the retropharynx. Postoperative dysphagia can be significant and consequently we recommend preoperative swallowing evaluation and counseling.

MALDI-MS derived prognostic protein markers for resected non-small cell lung cancer.

Protein signals obtained directly from frozen lung tissue sections using MALDI-MS were used to predict nodal involvement and survival in resected non-small cell lung cancer (NSCLC). We have identified a list of these protein signals and further evaluated their prognostic values for NSCLC using immunohistochemistry (IHC). Kaplan-Meier analysis was used to assess the mortality risk associated with the prognostic protein IHC-staining intensities. The combined IHC scores of calmodulin, thymosin ß4, and thymosin ß10 were found to be correlated with NSCLC patient survival (p = 0.004). Furthermore, low cofilin-1 IHC-staining intensity was found to be correlated with a better outcome for patients with negative lymph node status (p = 0.006) while high cofilin-1 IHC-staining intensity was found to be correlated with a better outcome for patients with positive node status (p = 0.034). In conclusion, the prognostic protein signals selected using MALDI-MS can be identified and tested by IHC in formalin-fixed tissue samples. MALDI-MS-derived protein signals can be potentially translated to a conventional clinical setting to aid in the prognosis of patients with NSCLC at the molecular level.

Colchicine intoxication diagnosed in a skin biopsy: a case report.

Colchicine toxicity is a rare, but well-described clinical entity. The histopathologic findings in various organ systems have been delineated in colchicine intoxication; however, skin findings have only been described in rare cases. We present a case of colchicine toxicity diagnosed on skin biopsy in a patient presenting with mental status changes. Her cutaneous manifestation consisted of a diffuse, blanchable, violaceous, morbilliform rash involving the trunk and proximal extremities. The histopathologic findings included metaphase-arrested keratinocytes with underlying basal vacuolization. These features, considered in the setting of multiorgan dysfunction and a known exposure of colchicine, led to the diagnosis.

Metastatic testicular seminoma to the prostate.

Prostatic involvement by seminoma is extremely rare. Four case studies have reported primary seminoma of the prostate. Three previous reports have been published of primary testicular seminoma with metastasis to the prostate. We report a fourth case with 10 years of follow-up and describe the initial management with orchiectomy and platinum-based chemotherapy, local pelvic tumor recurrence, subsequent salvage chemotherapy, and finally cystoprostatectomy with ileal neobladder. The patient was disease free at last follow-up 4 years after surgery.