Size-dependent steady state saturation limit in biomolecular transport through nuclear membranes.

The nucleus preserves the genomic DNA of eukaryotic organisms and maintains the integrity of the cell by regulating the transport of molecules across the nuclear membrane. It is hitherto assumed that small molecules having a size below the passive permeability limit are allowed to diffuse freely to the nucleus while the transport of larger molecules is regulated via an active mechanism involving energy. Here we report on the kinetics of nuclear import and export of dextran molecules having a size below the passive permeability limit. The studies carried out using time-lapse confocal fluorescence microscopy show a clear deviation from the passive diffusion model. In particular, it is observed that the steady-state concentration of dextran molecules inside the nucleus is consistently less than the concentration outside, in contradiction to the predictions of the passive diffusion model. Detailed analysis and modeling of the transport show that the nuclear export rates significantly differ from the import rates, and the difference in rates is dependent on the size of the molecules. The nuclear export rates are further confirmed by an independent experimental study where we observe the diffusion of dextran molecules from the nucleus directly. Our experiments and transport model would suggest that the nucleus actively rejects exogenous macromolecules even below the passive permeability limit. This result can have a significant impact on biomedical research, especially in areas related to targeted drug delivery and gene therapy.

A randomized study for dosimetric assessment and clinical impact of bone marrow sparing intensity-modulated radiation therapy versus 3-dimensional conformal radiation therapy on hematological and gastrointestinal toxicities in cervical cancer.

Background: Cervical cancer requires multimodality therapy, resulting in acute toxicities. Intensity-modulated radiation therapy (IMRT) is postulated to spare bone marrow (BM) and bowel to reduce acute hematological and gastrointestinal (GI) toxicities of chemoradiotherapy. Patients and Methods: This is a prospective randomized phase III study enrolling patients with Stage IB to IVA cervical carcinoma in two arms receiving either three-dimensional conformal radiotherapy (3DCRT) or IMRT from December 2017 to December 2019. The primary objective was to compare the hematologic toxicities (Grade 2 or more neutropenia as the primary factor) and the secondary objectives were to compare GI toxicities, and dosimetric analysis for volumes of BM, and bowel irradiated. SPSS version 20 was used for all statistical calculations. Results: Eighty patients with histopathologically confirmed cervical cancer were randomized to receive IMRT or 3DCRT (40 in each arm). The median age of the patients was 56.5 (36-67) and 59.5 (37-68) years, respectively, in IMRT and 3DCRT arms. The median dose of external radiation was 50 Gy in 25 fractions, and of brachytherapy was 24 Gy in 3 fractions in both the arms. The incidence of grade ≥2 neutropenia was 42.5% and 15% in the 3DCRT and IMRT arms, respectively (P < 0.001). All patients received concurrent chemotherapy with cisplatin, with the median number of cycles being 5 (range 3-5) in both the arms. All five cycles of concurrent chemotherapy could be completed in 25 (62.5%) patients in the IMRT arm and 24 (60%) patients in the 3DCRT arm. Conclusions: IMRT significantly reduces acute hematologic and GI toxicities compared with 3DCRT with a better dosimetry profile.

Confocal imaging of single BaTiO3 nanoparticles by two-photon photothermal microscopy.

We report on the development of a nonlinear optical microscopic technique based on two-photon absorption induced photothermal effect capable of detecting individual nonfluorescent nanoparticles with high sensitivity. The method which is inherently confocal makes use of near infrared excitation at high repetition rates and would be of interest in deep tissue imaging. We demonstrate the applicability of the technique by imaging single BaTiO3 nanoparticles, a potential biomolecular label having high photostability, in a scattering environment at fast time scales with a pixel dwell time of 80 µs.

High-dose-rate interstitial brachytherapy in head and neck cancer: do we need a look back into a forgotten art - a single institute experience.

PURPOSE: To evaluate the treatment outcomes with high-dose-rate (HDR) interstitial brachytherapy (HDR-BRT) in head and neck cancers (HNC). MATERIAL AND METHODS: Fifty-eight patients with HNC as per American Joint Committee on Cancer (AJCC) TNM staging criteria were analyzed retrospectively between 2008 and 2015. Forty-two patients received external beam radiotherapy (EBRT) with HDR-BRT and 16 patients received BRT alone. The survival was calculated with respect to median biological equivalent doses (BED) and median 2 Gy equivalent dose (EQD2), keeping α/ß = 10 for tumor. Loco-regional control and disease free survival was assessed. RESULTS: The median follow-up period was 25 months (2-84 months). The disease-free survival (DFS) probability at year 1 was 82.7%, and 68% at year 7. The overall survival probability was 91.3% at year 1 and 85.8% at year 7. The local control rate was 70%. The rate of recurrence was 30%. Distant metastasis rate was 17.2%. The median BED and EQD2, respectively, were 86.78 Gy and 71.6 Gy. The DFS was 74.1% and 75.9% in patients receiving a dose more than median BED and EQD2, respectively, and was 64.8% and 61.5% for less than the median dose. CONCLUSIONS: The overall outcome was good with implementation of HDR-BRT used alone or as boost, and shows DFS as better when the dose received is more than the median BED and median EQD2. The role of HDR-BRT in HNC is a proven, effective, and safe treatment method with excellent long term outcome as seen in this study, which reflects the need for reviving the forgotten art and science of interstitial brachytherapy in HNC.

Ludwig's Angina: A Nightmare Worsened by Adverse Drug Reaction to Antibiotics.

A 52-year-old obese gentleman presented to the hospital with complaints of fever and shortness of breath for 10 days. He was admitted in the ward and treated for acute exacerbation of asthma. He was shifted to the Intensive Care Unit (ICU) for persistent fever, neck swelling, airway obstruction and desaturation. Ludwig's angina was suspected and computed tomography of neck confirmed it. A difficult airway was anticipated and preceded with surgical tracheostomy. The patient had hypersensitivity reactions to piperacillin/tazobactam; hence, he was treated with clindamycin and metronidazole. The patient improved and was discharged after five days of ICU stay and 12 days of hospitalization. This case summarizes the rare incidence of Ludwig's angina with antibiotic adverse reactions. If angioneurotic edema is coincidental with features of Ludwig's angina, it becomes more challenging. Early identification, securing the airway, and antibiotic administration are the keystone to better survival.

Laser scanning photothermal microscopy: fast detection and imaging of gold nanoparticles.

We report on the design and construction of a laser scanning photothermal microscope and present images of gold nanoparticles of size as small as 5 nm. Laser scanning method allows fast image acquisition at 80 µs pixel dwell time so that a 500 × 500 pixel image is acquired in 20 s. Photothermal imaging at fast time scales can have potential applications in variety of fields including tracking of biomolecular transport processes.

Agrobacterium-mediated genetic transformation of oilseed Brassica campestris: Transformation frequency is strongly influenced by the mode of shoot regeneration.

Protocols were developed for efficient shoot regeneration from hypocotyl and cotyledon explants of oilseed Brassica campestris (brown sarson) cv. 'Pusa Kalyani'. These were used for genetic transformation by an Agrobacterium based binary vector carrying neomycin phosphotransferase (npt) gene and ß-glucuronidase (gus)-intron gene for plant cell specific expression. Transformed plants were recovered from hypocotyl explants at a frequency of 7-13%. Addition of silver nitrate markedly enhanced shoot regeneration in hypocotyl explants under non-selection conditions and was found to be an absolute requirement under selection conditions. Cotyledon explants, inspite of being more regenerative, proved to be highly refractory to transformation. Only two chimeric transformed shoots were obtained from more than 10,000 cotyledons treated with Agrobacterium. In hypocotyl explants, shoot regeneration occurred from the vascular parenchyma both with and without the intervention of callus phase. Only the shoot buds differentiating from callus tissue were positive for GUS activity. In cotyledons, shoot buds originated only directly from the vascular parenchyma, generally at a distance of about 450-625 µ from the cut surface. Such shoots were negative for GUS activity.