Solvation dynamics by coherence period resolved transient grating.

We report a third-order nonlinear time-domain method, coherence period (τ) resolved transient grating (TRTG), that gives accurate solvation dynamics free from population relaxation in a short data acquisition time. The validity of TRTG is established by theory and experiment. The TRTG signal is shown to follow the transition frequency correlation function by an analytic expression based on the response function theory for delta function pulses and by model numerical calculations including finite pulse durations. TRTG is demonstrated for two cyanine dyes IR144 and IR125 in methanol by using a diffractive-optics based four wave mixing apparatus. Solvation dynamics in methanol obtained from the TRTG are consistent with those reported previously confirming the validity of TRTG.

Factors influencing intraoral removal of submandibular calculi.

OBJECTIVES: To assess the effectiveness of intraoral removal of submandibular calculi based on several factors that may influence the results of surgery. STUDY DESIGN AND SETTING: We retrospectively reviewed 172 patients who underwent intraoral removal of submandibular sialolithiasis. Results of surgery were divided into complete removal, partial removal, and failure. The effect of location, palpability, size, and presence of infection of the calculi on the results was estimated. RESULTS: Univariate analysis showed that palpability and presence of infection were statistically significant factors affecting intraoral removal. Palpability was the only significant factor after multivariate analysis. Twelve of 13 patients with recurrent calculi underwent repeat intraoral removal successfully. CONCLUSIONS: The palpability of submandibular calculi is the most important factor influencing their successful intraoral removal. SIGNIFICANCE: Intraoral removal can be performed successfully regardless of location, size, presence of infection, or recurrence of calculi, if the calculi are palpable.

A Calcitonin-Negative Neuroendocrine Tumor Derived from Follicular Lesions of the Thyroid.

Neuroendocrine lesions of the thyroid are rare. The most common types are medullary thyroid carcinomas (MTCs) and C-cell hyperplasia. MTCs originate from thyroid parafollicular cells that secrete calcitonin which serves as a serum marker of MTCs. Here, the rare case of a calcitonin-negative neuroendocrine tumor (NET) derived from follicular lesions of the thyroid is described. A 34-year-old man presented at our hospital for the surgical management of an incidental thyroid nodule that was observed on an ultrasound sonography (USG) of the neck. Initially, USG-guided aspiration cytology was performed, and a MTC was suspected. The expressions of thyroglobulin and thyroid transcription factor-1, which are thyroid follicular cell markers, and synaptophysin and chromogranin A, which are neuroendocrine markers, was confirmed following surgical pathology. However, the staining of calcitonin, a marker of MTCs, was not observed. A nonmedullary NET of the thyroid is uncommon, and the distinction between calcitonin-negative NETs and MTCs of the thyroid may be important due to differences in their clinical courses and management.

BRAFV600E mutation does not serve as a prognostic factor in Korean patients with papillary thyroid carcinoma.

OBJECTIVES: In recent years, BRAF(V600E) mutation has emerged as a promising prognostic marker for risk stratification of patients with papillary thyroid carcinoma (PTC). However, routine use of this marker has been questioned. In some parts of the world, particularly in Korea, the incidence of BRAF(V600E) mutation is too high to have true prognostic value. The relatively low number of tumors without BRAF(V600E) mutation would prejudice the efficient use of this marker in the Korean population. METHODS: The study involved 107 patients with histologically confirmed conventional PTC after surgical management for thyroid cancer from April 2010 to December 2010. BRAF(V600E) mutation analysis was performed by polymerase chain reaction (PCR)-based amplification of DNA extracted from paraffin-embedded tumor specimens, and the relationship between BRAF(V600E) mutation and various prognostic factors was investigated. RESULTS: BRAF(V600E) mutation was found to be present in 85 (79.4%) of 107 patients with conventional PTC. Analysis of the clinical characteristics as function of the presence or absence of BRAF(V600E) mutation revealed no differences between the BRAF(V600E)-positive and BRAF(V600E)-negative patients. Moreover, BRAF(V600E) mutation was not correlated with any of the prognostic factors including age ≥45 years, male gender, tumor size ≥1cm, multifocality, extra-thyroidal extension, concurrent Hashimoto's thyroiditis, and lymph node metastasis neither in the univariate nor in the multivariate analysis. CONCLUSIONS: BRAF(V600E) mutation does not significantly reflect tumor aggressiveness in Korean patients with conventional PTC. We consider that BRAF(V600E) mutation does not possess prognostic value in Korea, where it is prevalent, and where most of the PTC types are conventional.

Coherent interactions in femtosecond transient grating.

Transient grating of a dye in liquid has been measured as a function of the electronic coherence period. A diffractive beam splitter and a pair of wedge prisms are implemented to achieve precise spatial phase overlap and interferometrically accurate control of the time delay between the pump pulses. As the electronic coherence period is varied, coherent interactions lead to an enhancement or loss of the sharp feature in the transient grating signal near time zero, which is usually called coherent spike. Sensitivity of the transient grating signal to the solvation process also changes by the coherence time delay. All the features can be accounted for by invoking third-order nonlinear response functions. Numerical simulations have been performed to corroborate our description. This work identifies a major source of the coherent spike in the transient grating and transient absorption experiments. In addition, it allows us to propose a method that measures the solvation function more efficiently than conventional transient grating technique does.