Monte Carlo Study of Unflattened Photon Beams Shaped by Multileaf Collimator

INTRODUCTION

This study investigates basic dosimetric properties of unflattened 6 MV photon beam shaped by multileaf collimator and compares them with those of flattened beams.

MATERIALS AND METHODS

Monte Carlo simulation model using BEAM code was developed for a 6MV photon beam based on Varian Clinic 600 unique performance linac operated with and without a flattening filter in beam line. Dosimetric features including lateral profiles, central axis depth dose, photon and electron spectra were calculated for flattened and unflattened cases, separately.

RESULTS

An increase in absolute depth dose with a factor of more than 2.4 was observed for unflattened beam which was dependent on depth. PDDs values were found to be lower for unflattened beam for all field sizes. Significant decrease in calculated mlc leakage was observed when the flattening filter was removed from the beam line. The total scatter factor, S_CP was found to show less variation with field sizes for unflattened beam indicating a decrease in head scatter. The beam profiles for unflattened case are found to have lower relative dose value in comparison with flattened beam near the field edge, and it falls off faster with distance.

CONCLUSION

Our study showed that increase in the dose rate and lower peripheral dose could be considered as realistic advantages for unflattened 6MV photon beams.

Retrospective study on outcome of macular hole surgery

INTRODUCTION

Macular hole is a common and treatable cause of central visual loss. Classic macular hole surgery consists of vitrectomy, posterior vitreous cortex removal and intraocular gas tamponade, but during the past decade focus has especially been on internal limiting membrane (ILM) peeling as adjuvant therapy for increasing closure rates.

OBJECTIVE

To determine and evaluate anatomical and visual outcome of macular hole surgery.

MATERIALS AND METHODS

Retrospective analysis of all cases of macular hole surgery done by single surgeon between 2014 -2015.

RESULTS

16 eyes were analysed with follow up of 3 months. Macular hole closure after vitrectomy was 75% with visual improvement of two or more line in 62.5%.Post surgical complication included cataract 18.8%, Increased IOP 12.5% and retinal detachment 6.2%.

CONCLUSION

Vitrectomy along with ILM peeling and Gas Tamponade with effective positioning improves in visual acuity and achieve hole closure in people with macular hole.

Phytostimulatory effect of silver nanoparticles (AgNPs) on rice seedling growth: An insight from antioxidative enzyme activities and gene expression patterns

The knowledge on the mode of action, biocompatibility and ecological tolerance of silver nanoparticles (AgNPs) is gradually accumulating over the years with contradictory findings. Most of the studies indicated the toxic impact of AgNPs on plant growth and development, where induction of oxidative stress was considered to be one of the causal factors. The present study demonstrates the phytostimulatory effect of bio-synthesized silver nanoparticles (AgNPs) during seed germination and seedling growth of rice (Oryza sativa L., cv. Swarna) under in vitro condition. All the tested concentrations of AgNPs (10, 20, 40 ppm) promote both the shoot and root growth which was evident from the increased length and biomass of the seedlings. Exposure to AgNPs also significantly increased the chlorophyll a and carotenoid contents. The content and the pattern of distribution of phenolic metabolites among the different treatments are indicative of non-toxic impact of AgNP mimicking mild or no stress to the seedlings. Growth stimulation of rice seedlings by AgNPs was further supported by a low level of reactive oxygen species (ROS) concomitant with decreased amount of lipid peroxidation and H₂O₂ content, compared to control. In order to unravel the stimulatory impact of AgNPs on rice seedling growth, the present study also describes the AgNPs induced changes in antioxidative enzyme activity and related gene expression levels. Elevated levels of catalase (CAT), ascorbate peroxidase (APX) and glutathione reductase (GR) activities were recorded in all the AgNPs treated seedlings with improved growth. The activity of superoxide dismutase (SOD) was not significantly altered at low concentration of AgNPs. It appears that enzymes of ascorbate cycle, APX and GR are more active in ensuring protection against oxidative damage than SOD. There was significant up-regulation of CAT and APX gene expressions in seedlings exposed to AgNPs, whereas the expression level of CuZnSOD gene was decreased gradually with an increase in the concentration of AgNPs. The antioxidant enzyme activities and gene expression patterns coupled with the levels of H₂O₂ and lipid peroxidation indicates that the efficiency of redox reactions was increased in the presence of AgNPs and that accelerates the seedling growth.

Spin-Resolved Spectroscopy of the Yu-Shiba-Rusinov States of Individual Atoms

A magnetic atom in a superconducting host induces so-called Yu-Shiba-Rusinov (YSR) bound states inside the superconducting energy gap. By combining spin-resolved scanning tunneling spectroscopy with simulations we demonstrate that the pair of peaks associated with the YSR states of an individual Fe atom coupled to an oxygen-reconstructed Ta surface gets spin polarized in an external magnetic field. As theoretically predicted, the electron and hole parts of the YSR states have opposite signs of spin polarizations which keep their spin character when crossing the Fermi level through the quantum phase transition. The simulation of a YSR state right at the Fermi level reveals zero spin polarization which can be used to distinguish such states from Majorana zero modes in chains of YSR atoms.

C-reactive Protein in Periodontitis and its Comparison with Body Mass Index and Smoking Behaviour

INTRODUCTION

Chronic periodontitis is an infectious disease resulting in inflammation within the supporting tissues of the teeth, progressive attachment loss, and bone loss. In addition to declining oral health, there is always low grade infection present in periodontitis. Studies show increased levels of systemic biomarkers in periodontal disease such as CRP, which is considered a key-marker of CVD. Research has also shown positive association between BMI and smoking with periodontitis and CRP. The objective of the study was to assess the levels of CRP in patients with and without periodontitis and their relation with BMI and smoking behaviour.

METHODS

Patients visiting the Dental department of Bir Hospital were invited to participate in the study. Total 31 subjects in each group: Case (periodontitis) and Control (without periodontitis) were selected using convenience sampling technique. All subjects underwent periodontal examination by a single examiner. Serum CRP samples were taken before periodontal treatment. Data analysis was done by SPSS 17 software program.

RESULTS

Increase in mean CRP levels in periodontitis (5.8595mg/L) with high statistical significance (P=0.000) in comparison to subjects without periodontitis (1.1214mg/L) was observed. BMI showed positive association with periodontitis (P=0.046) but not with CRP (0.213). Smoking behaviour showed no significant relation with either CRP (P=0.344) or periodontitis (P=0.541).

CONCLUSIONS

We found highly significant association between periodontitis and CRP levels but not always with BMI and smoking. CRP, which is an established marker for CVD was significantly increased in periodontal infections. Hence, a close interaction among Physician, Periodontist and Patient to prevent adverse health situations is recommended.

Blood Lead Level among school children in an Industrial city of Nepal

Background: Widespread use of lead has caused extensive environmental contamination and health problems in many parts of the world. Children are particularly vulnerable and even relatively low levels of exposure can cause serious health conditions. Our objective was to determine the prevalence of blood lead level in children in industrial city of Nepal, Birgunj.Materials and Methods: The cross sectional study was done on 50 school going student in Birgunj city, Nepal from November 2016 to January 2017. Questionnaire was used to collect data. Capillary blood was drawn and Blood Lead Level was measured immediately. SPSS ver. 22 was used to analyze the data.Results: The mean age of children in study was 12.5 ± 1.11 years.Among 50 children, 54% were male and 46% were female. The mean blood lead level was 20.33±9.36 μg/dl (male 21.08±8.87μg/dl, female 19.46±10.92 μg/dl). All the children in the study have elevated blood lead level and 84% of them have >10 μg/dl. About 26% of children have blood lead level between 15-20 μg/dl, 12% have level 20-25 μg/dl and 4% of them have more than 35 μg/dl.Conclusion: The prevalence of blood lead level in children from the industrial city of Nepal is alarmingly high. Children exposed with chipped paints have high level of blood lead level. However, further study in large population is required to address the current situation regarding the lead exposure to children.  

Impact of consultant specialty on discharge decisions in patients admitted as medical emergencies to hospitals in the United Kingdom

BACKGROUND

The Society for Acute Medicine's Benchmarking Audit (SAMBA) annually examines Clinical Quality Indicators (CQIs) of the care of patients admitted to UK hospitals as medical emergencies.

AIM

The aim of this study is to review the impact of consultant specialty on discharge decisions in the SAMBA data-set.

DESIGN AND METHODS

Prospective audit of patients admitted to acute medical units (AMUs) on 25 June 2015 to participating hospitals throughout the UK with subgroup analysis.

RESULTS

Eighty-three units submitted patient data from 3138 patients.Nearly 1845 (58%, IQR for units 50-69%) of patients were referrals from Emergency Medicine, 1072 (32%, IQR for units 24-44%) were referrals from Primary Care. The mean age was 65 (SD 20). One hundred and forty-one (4.5%) patients were admitted from care homes and 951 (30%) of patients were at least 'mildly frail' and 407 (13%) had signs of physiological instability. The median and the mean time to being seen by a doctor were 1 h 20 min and 2 h 3 min, respectively. The median and the mean time to being seen by senior specialist were 3 h 55 min and 5 h 56 min, respectively. By 72 h, 29 (1%) patients had died in the AMU, 73 were admitted to critical care units, 1297 (41%) had been discharged to their own home and 60 to nursing or residential homes. For every 100 patients seen specialists in acute medicine discharged 12 more patients than specialists from other disciplines of medicine ( P  < 0.001). The difference remained significant after adjustment for case mix.

CONCLUSION

Specialist in acute care might facilitate discharge in a higher proportion of patients.

Effects of dietary supplementation of cinnamaldehyde and formic acid on growth performance, intestinal microbiota and immune response in broiler chickens

An experiment was conducted to investigate the effects of replacing antibiotic growth promoter (AGP) with a combination of essential oil and organic acids (EO + OA) on growth performance, gut microbiota and immune response in broiler chickens. In Experiment 1, 320 day-old broiler chicks were randomly distributed to 32 pens with 10 birds in each pen and the pens were equally allotted to four treatment groups. In Experiment 2, 120 day-old chicks were divided into the same four treatment groups, each group containing three replicated pens with 10 birds in each pen. The groups were (1) Negative Control (NC) without AGP or other growth-promoting feed additives; (2) AGP (NC + enramycin; 125 mg/kg feed; (3) OA (NC + OA; 500 mg/kg feed); and (4) EO + OA (NC + a combination of cinnamaldehyde and calcium formate; 500 mg/kg feed). Experiment 1 lasted for 40 days, whereas Experiment 2 continued for 28 days. In Experiment 2, all birds were orally challenged with Escherichia coli (108 bacteria/bird) on Day 14. Overall intake, growth and feed conversion ratio (FCR) on Day 40 had no difference (P > 0.05) among the groups in Experiment 1. In Experiment 2, growth, feed intake and FCR were not affected by any dietary treatments until Day 14, but after being challenged with E. coli, bodyweight gain and FCR improved (P < 0.05) for AGP and EO + OA compared with NC. Mortality rate was also lower (P < 0.05) for AGP and EO + OA than NC in Experiment 2. Villi height was higher (P < 0.001) in OA and EO + OA groups compared with NC and AGP groups. Any treatment did not affect (P > 0.05) the counts of total bacteria, E. coli and Lactobacillus in the contents of ileum and caecum. However, Salmonella counts in the ileal and caecal contents decreased (P < 0.001) for AGP, OA and EO + OA compared with NC group. Clostridium counts were lower for EO + OA group than for NC and AGP groups in the ileum, and for AGP, OA and EO + OA groups than for NC in the caeca (P < 0.05). Antibody titer on Day 35 against Newcastle disease vaccine was higher in EO + OA group than in NC, AGP and OA groups (P < 0.001). In conclusion, EO + OA did not affect growth and FCR in broilers. However, AGP and EO + AO improved growth performance and FCR after being challenged with E. coli. Moreover, EO + OA was effective in reducing the Clostridium count in the small intestine and caecum and increasing the villus height and antibody titer against Newcastle disease vaccine.

Role of S-100 Immunostain as An Auxiliary Diagnostic Aid in Leprosy

INTRODUCTION

Histopathologic diagnosis of leprosy is difficult when Bacillary Index (BI) is zero and neural involvement are not easily identifiable on routine Hematoxylin and Eosin stain. This study was undertaken to study the role of S-100 immunostaining in demonstrating different patterns of nerve involvement in various types of leprosy.

METHODS

Thirty one skin biopsies with clinico-histopathologic diagnoses of leprosy over a period of two years were included in the study. Ten cases of non-lepromatous granulomatous dermatoses (including eight cases of lupus vulgaris and two cases of erythema nodosum) were used as controls. Tissue sections from all cases and controls were stained with Hematoxylin and Eosin (H&E) stain, Fite stain and S-100 immunostain. The H&E stained slides were used to study the histopathological features, Fite stained slides for Bacillary Index and S-100 for nerve changes.

RESULTS

Neural changes could be demonstrated in the entire spectrum of leprosy using S-100 immunostaining. The most common pattern of nerve destruction in the tuberculoid spectrum was fragmented and infiltrated whereas lepromatous spectrum showed mostly fragmented nerve twigs. Intact nerves were not detected in any of the leprosy cases.

CONCLUSIONS

S-100 immunostain is a useful auxiliary aid to the routine H&E stain in the diagnosis of leprosy especially tuberculoid spectrum and intermediate leprosy.