Multiresolution,model-based segmentation of MR angiograms

During the last decade, the quality of MR angiograms has risen substantially and their clinical utility has been demonstrated progressively. This acceptance has created a need for tools with which to summarize and display the information available. We have used a model-based segmentation technique to extract vascular morphology and local flow parameters from phase contrast MR angiograms. A multiresolution data structure is used as the basis of recursive decision-making to identify regions of blood flow. The resulting data representation allows more efficient data handling in subsequent processing and visualization and is directly applicable to the creation of a connected graph model of vascular regions. We describe this flow feature extraction algorithm and demonstrate the utility of the results.     

Bounds in the Sensitivity of BioMEMS Devices for Cell Detection

This paper presents an ongoing effort to characterize performance and reliability of micro electromechanical systems used for biomedical diagnostics (BioMEMS). In order to study the interactions of human osteosarcoma (HOS) cells with BioMEMS devices, cultures were performed on silicon (Si) surfaces as well as silicon surfaces coated with 50 nm of titanium (Ti). Cell spreading on the surfaces was observed over time for up to 2 hours. It was seen that titanium coated silicon surfaces have the potential to provide a better interface for BioMEMS devices, due to enhanced adherence and spreading of the cells on these surfaces. Atomic force microscope (AFM) cantilevers were used as cell detection sensors. These cantilevers were coated with 50nm of titanium metal to provide a cell friendly surface. Theoretical models were then developed for the prediction of the vibrational responses of the AFM cantilevers before and after cell attachment. The models were used to relate the experimentally observed changes in frequency to the number of cells that are attached on the cantilever. The bounds in the possible frequency changes were determined within a theoretical framework. From experimentally calculated values for the mass of cells, random number simulations were carried out to determine the probability of cell attachment as a function of the change in resonance frequency of the cantilever sensor. The implications of the results are then discussed for the future reliability modeling of the sensor.     

Study of processing parameters influencing the properties of Diltiazem hydrochloride microspheres

Diltiazem hydrochloride-ethylcellulose microspheres were prepared by the water-in-oil emulsion-solvent evaporation technique. Small and spherical microspheres having a mean microsphere diameter in the range of 40-300 µm and entrapment efficiency of ~60-90% were obtained. Scanning electron micrographs of drug-loaded microspheres showed the presence of uniformly distributed small pores and absence of drug crystals on their surface, indicating simultaneous precipitation of drug and the polymer from the solvent during solvent evaporation. Differential scanning calorimetric analysis confirmed the absence of any drug-polymer interaction. The in vitro release profile could be altered significantly by changing various processing parameters to give a controlled release of drug from the microspheres. The stability studies of the drug-loaded microspheres showed that the drug was stable at storage temperatures, 5-55°C, for 12 weeks.     

Transcatheter closure of perimembranous ventricular septal defect with amplatzer membranous occluder

BACKGROUND: Use of trancatheter device closure for membranous ventricular septal defect is still in evolving phase. We report the early and mid-term results of our experience with the new asymmetric Amplatzer membranous ventricular septal defect occluder. METHODS AND RESULTS: We attempted, transcatheter closure of perimembranous ventricular septal defect using asymmetric Amplatzer occluder in 26 patients. The patients were selected on the basis of transthoracic and transesophageal echocardiographic assessment of the ventricular septal defect. The procedure was successful in 21 (81%) patients. The age ranged from 3 to 23 years, weight from 10 to 59 kg and defect size ranged from 3 to 9 mm (mean: 5 +/- 1.8 mm). One patient had situs inversus with dextrocardia: 11 had aneurysmal tissue partly occluding the defect and the device was deployed either across (n=6) or within the aneurysmal sac (n=5). Three patients developed high degree atrioventricular block on attempts to cross the defect with the sheath and the procedure was discontinued. In two patients it was not possible to place the sheath in left ventricle despite repeated attempts. There was a residual flow in 4 (19%) patients at 24 hours. Two patients developed bundle branch block and none had complete heart block. At follow-up (1-9 months, n=20), residual flow was seen in two patients. None developed late conduction defect, aortic regurgitation, infective endocarditis or hemolysis. CONCLUSIONS: Transcatheter closure of perimembranous ventricular septal defect can be performed safely and effectively with the new asymmetric Amplatzer occluder device in selected patients with good short- and midterm results. These devices can be deployed safely in and across and the aneurysmal sacs. In selected cases, this procedure is a satisfactory alternative to surgery.     

Penetrating injury of the cornea by a barbed fish hook and its surgical management by “Cut-it out technique”

Fishing is a worldwide pastime enjoyed by millions of people. Ocular fishing injuries though uncommon may cause potentially devastating ocular trauma. We report a rare case of penetrating injury of the cornea by a barbed fish hook and its successful surgical management by “cut-it out technique”. We are discussing the various techniques available for removal of fish hooks. The hook can be successfully removed with minimal trauma to ocular structures by understanding the structure of the fish hook and by employing the appropriate method of extraction.     

Cytokinin signaling regulates cambial development in poplar

Although a substantial proportion of plant biomass originates from the activity of vascular cambium, the molecular basis of radial plant growth is still largely unknown. To address whether cytokinins are required for cambial activity, we studied cytokinin signaling across the cambial zones of 2 tree species, poplar (Populus trichocarpa) and birch (Betula pendula). We observed an expression peak for genes encoding cytokinin receptors in the dividing cambial cells. We reduced cytokinin levels endogenously by engineering transgenic poplar trees (P. tremula × tremuloides) to express a cytokinin catabolic gene, Arabidopsis CYTOKININ OXIDASE 2, under the promoter of a birch CYTOKININ RECEPTOR 1 gene. Transgenic trees showed reduced concentration of a biologically active cytokinin, correlating with impaired cytokinin responsiveness. In these trees, both apical and radial growth was compromised. However, radial growth was more affected, as illustrated by a thinner stem diameter than in WT at same height. To dissect radial from apical growth inhibition, we performed a reciprocal grafting experiment. WT scion outgrew the diameter of transgenic stock, implicating cytokinin activity as a direct determinant of radial growth. The reduced radial growth correlated with a reduced number of cambial cell layers. Moreover, expression of a cytokinin primary response gene was dramatically reduced in the thin-stemmed transgenic trees. Thus, a reduced level of cytokinin signaling is the primary basis for the impaired cambial growth observed. Together, our results show that cytokinins are major hormonal regulators required for cambial development.     

Changing trend in the morphology of cataracts at a tertiary eye care centre in South India due to COVID-19-pandemic related national lockdown

Purpose:To study the changing trends in the morphology of cataracts at a tertiary eye care center in South India due to COVID-19 pandemic-related national lockdown.Methods:A retrospective study conducted at a tertiary eye care center in Andhra Pradesh state of South India, which included 1724 patients (1753 eyes) who underwent cataract surgery at our center during April 2019–July 2019 (1298 eyes of 1271 patients) and April 2020–July 2020 (455 eyes of 453 patients). Factors studied included preoperative lens status, associated phacodonesis or subluxation, pupil size, other eye lens status, associated retinal problems, glaucoma, and complications during surgery. Postoperative uncorrected visual acuity (UCVA), best-corrected visual acuity (BCVA), corneal clarity, intraocular pressure (IOP), and disc status at postoperative day 1, 1 week, and 1-month visits were compared.Results:A significantly lower proportion of nuclear sclerosis (decreased from 83.2% in last year before lockdown to 55.2% during lockdown) and significantly higher proportions of mature, brown, or black cataract and phacomorphic, phacolytic, or Morgagnian cataract (increased from 15.5% in last year before lockdown to 43.8% during lockdown) were observed. The proportion of small-incision cataract surgery decreased significantly (from 63.2% to 57.4%), whereas the proportion of phacoemulsification increased significantly (from 35.9% to 41.5%) during lockdown as compared to last year. A significantly higher proportion of eyes with small pupils and association with retinal pathology were also observed during the lockdown.Conclusion:During the national lockdown, there was a shift from nuclear sclerosis grade toward mature, brown, black grade of cataracts. In addition, the proportion of small-incision cataract surgery decreased significantly whereas the proportion of phacoemulsification increased significantly during the lockdown. More number of cataracts with small pupils and associated retinal pathology were observed during the lockdown.     

Cytotoxicity screening of Bangladeshi medicinal plant extracts on pancreatic cancer cells

Background  

There has been a long standing interest in the identification of medicinal plants and derived natural products for developing cancer therapeutics. Our study focuses upon pancreatic cancer, due to its high mortality rate, that is attributed in part to the lack of an effective chemotherapeutic agent. Previous reports on the use of medicinal plant extracts either alone or alongside conventional anticancer agents in the treatment of this cancer have shown promising results. This work aims to investigate the therapeutic properties of a library of medicinal plants from Bangladesh.