Mechanical Characterization and Standardization of Silicon Scalp and Dura Surrogates for Neurosurgical Simulation

BACKGROUND

Simulation-based neurosurgical training allows the development of surgical skills outside the operating room. However, the use of nonstandardized materials and poor haptic feedback remain the primary limitations of the surgical simulators. Therefore, this work proposes a comprehensive scheme for scalp and dura surrogate synthesis and their standardization for neurosurgical training.

METHODS

Eight different variants of silicone-based scalp (S1-S8) and dura (D1-D8) surrogates were synthesized. The samples were evaluated by 26 neurosurgeons. They provided their feedback in a Likert scale questionnaire. Kruskal-Wallis test with Dunn multiple comparisons was used for statistical analysis of surgeons' scores. The samples were mechanically characterized using Shore A hardness and dynamic nanoindentation testing.

RESULTS

The highest mean Likert score values were obtained for S3 scalp and D8 dura variants. The comparison of S3 and D8 with the rest of the variants in the respective groups was statistically significant in 21 of 28 instances. The average Shore A hardness and storage modulus of the S3 variant were 21.9 DU and 505.3 kPa, respectively. The corresponding values for the D8 variant were 32.5 DU and 632 kPa, respectively.

CONCLUSIONS

This study proposes a method for the synthesis, evaluation, and standardization of scalp and dura surrogates. The study achieved standardized silicone compositions along with a recommendable range of Shore hardness and viscoelastic moduli values for the scalp and dura surrogates. This work can be extended for the standardization of surrogates for other tissues involved in neurosurgical simulators.

Evaluation of the Efficacy of Intralesional Measles, Mumps, and Rubella Vaccine with Intralesional Vitamin D3 as Immunotherapies in the Treatment of Recalcitrant Cutaneous Warts in Adult- A Randomized Placebo-Controlled Study

Introduction:

Currently, various destructive and ablative treatment options are conventionally used for warts, but all of them are limited in some form by their adverse effects, high recurrences, suboptimal effectiveness, and the need to treat every wart. Lately, immunotherapy has emerged as a safe treatment relying on biological substances that modulate the immune system to achieve disease control.

Aims and Objectives:

We aimed at conducting a placebo-controlled study to compare the rate of efficacy of intralesional MMR vaccine with vitamin D3 in the management of recalcitrant extragenital warts in immune-competent adults. Follow-up was done at third and sixth month.

Materials and Methods:

Patients were divided into three groups, namely, group A, B, and C. Groups A, B, and C received intralesional MMR vaccine, vitamin D3 and normal saline, respectively, in the largest wart. The injections were repeated every 2 weeks, for a maximum of four injections.

Results:

Among injected warts, in group A, complete clearance was seen in 29 (87.8%) patients, partial clearance in two (6.1%) and no response in two (6.1%) patients. In group B, 24 (77.4%) patients, five (16.1%) patients, and two (6.5%) patients showed signs of complete, partial, and no clearance, respectively, in injected warts. Complete response in distant warts was seen in 25 (75.7%) patients in group A and 20 (64.5%) patients in group B. There was no statistically significant difference between responses of the two groups. In group C, only three (12.5%) patients had complete clearance in injected warts, and none in distant warts. Recurrence was seen in two (6.4%) patients, each in group B and C. However, for management of verruca plana MMR was found to be superior to vitamin D3.

Limitations:

Our study was limited by a small sample size, absence of immunological analysis, and limited follow-up period.

Conclusion:

MMR vaccine and vitamin D3 are equally effective and safe treatment option for multiple, recalcitrant warts, as well as warts on difficult to treat sites with minimal recurrence.

Sydenham's Chorea with Silent Cardiac Lesions, Mimicking

Sydenham's chorea is an uncommon neurological manifestation of rheumatic fever and has many and varied differential diagnosis. It may mimic encephalitis when presents as an isolated feature even when silent cardiac lesions are present. Early diagnosis, treatment and penicillin prophylaxis prevents recurrence and progression of cardiac lesions. Prompt symptomatic relief and alleviation of distress is obtained with therapeutic intervention. A case of rheumatic chorea with silent cardiac valve lesions which mimicked herpes simplex encephalitis with choreoathetosis, in a 13 year old girl is presented along with review of literature.

Estimating the Impact of Extragenital Warts versus Genital Warts on Quality of Life in Immunocompetent Indian Adult Patients: A Comparative Cross-Sectional Study

Background:

Extra-genital warts (EGWs) affect 7-10% of population. Even though a plethora of studies have been conducted to assess the impact of genital warts (GWs) showing a significant impact on the quality of life but surprisingly, barely any data has been collected on the impact of EGWs on quality of life.

Aims and Objective:

This cross-sectional study aimed at comparing the magnitude of EGWs on health-related quality of life and various variables with that of GWs.

Patients and Methods:

The study consisted of two groups of immunocompetent adults, each with 100 patients aged 18 years or above, attending the skin outpatient department at our tertiary center between April 2018 and March 2019 and consented to participate. Group A consisted of patients with EGWs and group B comprised of patients with GWs. All patients were asked to fulfill the validated Hindi hard copy of the Dermatology Life Quality Index (DLQI) questionnaire.

Results:

The mean DLQI score of patients with EGWs was 8.73 ± 0.84 and that of patients with GWs was 5.83 ± 0.83 (P = 0.026). In group A, those affected the most were patients with warts on multiple exposed sites (mean DLQI score of 14), followed by warts on feet (mean DLQI score of 10.69), followed by warts on hands (DLQI score of 9.12), and facial warts (DLQI score of 6.80). Patients with a prior history of failed treatment and/or a longer duration of illness had a higher level of dissatisfaction. To the best of our knowledge, no such study has been conducted in the past in our country.

Conclusions:

EGWs inflict a severe negative impact on the quality of life. Owing to its notorious persistence and recurrence, healthcare professionals must educate patients on how to prevent the spread and recurrence, discuss details of available treatment modalities while keeping in view the psychological and sociological impact.

Biomechanical modelling and computer aided simulation of deep brain retraction in neurosurgery

BACKGROUND AND OBJECTIVES

Surgical simulators are widely used to promote faster and safer surgical training. They not only provide a platform for enhancing surgical skills but also minimize risks to the patient's safety, operation theatre usage, and financial expenditure. Retracting the soft brain tissue is an unavoidable procedure during any surgery to access the lesioned tissue deep within the brain. Excessive retraction often results in damaging the brain tissue, thus requiring advanced skills and prior training using virtual platforms. Such surgical simulation platforms require an anatomically correct computational model that can accurately predict the brain deformation in real-time.

METHODS

In this study, we present a 3D finite element brain model reconstructed from MRI dataset. The model incorporates precisely the anatomy and geometrical features of the canine brain. The brain model has been used to formulate and solve a quasi-static boundary value problem for brain deformation during brain retraction. The visco-hyperelastic framework within the theory of non-linear elasticity has been used to set up the boundary value problem. Consequently, the derived non-linear field equations have been solved using finite element solver ABAQUS.

RESULTS

The retraction simulations have been performed for two scenarios: retraction pressure in the brain and forces required to perform the surgery. The brain was retracted by 5 mm and retained at that position for 30 minutes, during which the retraction pressure attenuates to 36% of its peak value. Both the model predictions as well as experimental observations on canine brain indicate that brain retraction up to 30 minutes did not cause any significant risk of induced damage. Also, the peak retraction pressure level indicates that intermittent retraction is a safer procedure as compared to the continuous retraction, for the same extent of retraction.

CONCLUSIONS

The results of the present study indicate the potential of a visco-hyperelastic framework for simulating deep brain retraction effectively. The simulations were able to capture the dominant characteristics of brain tissue undergoing retraction. The developed platform could serve as a basis for the development of a detailed model in the future that can eventually be used for effective preoperative planning and training purposes.

A comparative study of the efficacy and safety of intralesional measles, mumps, and rubella vaccine versus intralesional vitamin D3 for the treatment of warts in children

BACKGROUND

Intralesional vitamin D3 has recently emerged as a new treatment for cutaneous warts. The use of the measles, mumps, and rubella (MMR) vaccine for this purpose is an established modality. However, relevant data on the efficacy of either the MMR vaccine or vitamin D3 as immunotherapy for cutaneous warts in the pediatric population are limited.

OBJECTIVES

To compare the efficacy and safety of intralesional injections of MMR vaccine to intralesional injections of vitamin D3 in children aged 8-16 years with multiple warts.

METHODS

A total of 74 children were randomly allocated into two groups. Group A patients received intralesional MMR vaccine into the largest wart, and group B received intralesional vitamin D3 into the largest wart. The injections were repeated every 4 weeks until clearance or for a maximum of three treatments. After the last injection, children were followed up every 2 weeks for 3 months, and at the sixth month, a final clinical assessment was conducted.

RESULTS

Of 74 children, 60 completed the study, with 30 children in each group. Complete clearance of the injected wart was observed in 26 (86.67%) patients in the MMR group (group A) and 23 (76.7%) patients in the vitamin D3 group (group B). Distant warts cleared in 23 (76.7%) patients in group A compared to 20 (66.6%) patients in group B. There was no significant difference between groups. No recurrence was seen in group A, whereas two (6.6%) children in group B exhibited recurrence in the ensuing 6-month follow-up. The most common adverse events were injection site pain and swelling.

CONCLUSION

Both intralesional MMR and vitamin D3 are safe, generally well-tolerated, and equally effective in children for the treatment of cutaneous warts.

Slip pulse and resonance of the Kathmandu basin during the 2015 Gorkha earthquake, Nepal

Detailed geodetic imaging of earthquake ruptures enhances our understanding of earthquake physics and associated ground shaking. The 25 April 2015 moment magnitude 7.8 earthquake in Gorkha, Nepal was the first large continental megathrust rupture to have occurred beneath a high-rate (5-hertz) Global Positioning System (GPS) network. We used GPS and interferometric synthetic aperture radar data to model the earthquake rupture as a slip pulse ~20 kilometers in width, ~6 seconds in duration, and with a peak sliding velocity of 1.1 meters per second, which propagated toward the Kathmandu basin at ~3.3 kilometers per second over ~140 kilometers. The smooth slip onset, indicating a large (~5-meter) slip-weakening distance, caused moderate ground shaking at high frequencies (>1 hertz; peak ground acceleration, ~16% of Earth's gravity) and minimized damage to vernacular dwellings. Whole-basin resonance at a period of 4 to 5 seconds caused the collapse of tall structures, including cultural artifacts.

Highly tunable self-assembled plasmonic lattices through nanosphere lithography

This Letter reports a method to produce two-dimensional self-assembled plasmonic nanopillar (NP) arrays with independent control of the diameter (d), spacing (s), and height (h) of the NPs. A plasmonic lattice was designed and optimized for maximum plasmonic activity at 980 nm using three-dimensional finite-difference time-domain simulations. The optimized lattice with d=365 nm, s=410 nm, and h=70 nm was fabricated utilizing a self-assembled nanosphere lithography approach. Outstanding agreement between the observed and predicted results confirms the validity of the design process and the controllability and repeatability of the fabrication process. The excellent short-range order in the lattice structure suggests that this method can replace the electron-beam lithography approach in a scalable and cost-effective manner.

Controlled Synthesis of Si Nanopillar Arrays for Photovoltaic and Plasmonic Applications

This paper focuses on developing a robust process to independently control the geometrical parameters of Si nano-pillar (NP) arrays. These parameters include height and diameter of NPs, spacing between them, and the shape of the NPs. We have shown that the diameter, height, and spacing of NPs can be independently engineered by controlling the diameter of nano-beads through synthesis procedure, duration of isotropic SiO2 etching and duration of anisotropic Si etching, respectively.

Expression of cytokeratin 20 in urine cytology smears: a potential marker for the detection of urothelial carcinoma

BACKGROUND

Urine cytomorphology is one of the oldest methods for screening and monitoring patients with transitional cell carcinoma (TCC). Sensitivity of urine cytology is relatively low. Ancillary techniques on urine sample may increase the sensitivity.

AIM

To explore the utility of cytokeratin 20 (CK20) immunostaining in identifying malignant cells in urine cytology smears.

MATERIALS AND METHODS

Fourteen cases each of confirmed TCC and benign urinary cytology along with five cases of atypical cells in urine were immunostained with a monoclonal CK20 antibody. Of 14 cases of TCC, 12 showed strong positive staining with the antibody. All benign cases were negative except for a few cases in which the umbrella cells were weakly to moderately positive. In all five cases of atypical urine cytology the atypical cells stained positive with the antibody. These cases were later confirmed as TCC on histopathology of bladder wall biopsy.

CONCLUSION

CK20 is an important biomarker that can be used to identify TCC in urine cytology smears. It is particularly useful in those cases where malignancy cannot be confirmed by morphology alone.

Seasonal variations of natural ventilation and radon-222 exhalation in a slightly rising dead-end tunnel

The concentration activity of radon-222 has been monitored, with some interruptions, from 1997 to 2005 in the end section of a slightly rising, dead-end, 38-m long tunnel located in the Phulchoki hill, near Kathmandu, Nepal. While a high concentration varying from 6 x 10(3) Bq m(-3) to 10 x 10(3) Bq m(-3) is observed from May to September (rainy summer season), the concentration remains at a low level of about 200 Bq m(-3) from October to March (dry winter season). This reduction of radon concentration is associated with natural ventilation of the tunnel, which, contrary to expectations for a rising tunnel, takes place mainly from October to March when the outside air temperature drops below the average tunnel temperature. This interpretation is supported by temperature measurements in the atmosphere of the tunnel, a few meters away from the entrance. The temporal variations of the diurnal amplitude of this temperature indeed follow the ventilation rate deduced from the radon measurements. In the absence of significant ventilation (summer season), the radon exhalation flux at the rock surface into the tunnel atmosphere can be inferred; it exhibits a yearly variation with additional transient reductions associated with heavy rainfall, likely to be due to water infiltration. No effect of atmospheric pressure variations on the radon concentration is observed in this tunnel. This experiment illustrates how small differences in the location and geometry of a tunnel can lead to vastly different behaviours of the radon concentration versus time. This observation has consequences for the estimation of the dose rate and the practicability of radon monitoring for tectonic purposes in underground environments.

Spontaneous down-regulation of Fas-associated phosphatase-1 may contribute to excessive apoptosis in myelodysplastic marrows

In this study, we examined the role of Fas-signaling in the apoptotic pathway in myelodysplastic syndromes (MDS). Ficoll-separated mononuclear cells from 18 bone marrow aspirate specimens obtained from 17 MDS patients, 4 normal healthy donors, and 3 acute myeloid leukemia patients transformed from MDS (t-AML) were studied for mRNA expression of Fas-L, Fas, and the effectors of their signaling, Caspase 1 and Caspase 3, using reverse transcriptase polymerase chain reaction. Fas-L, Fas, and Caspase 1 were detectable in all of the samples in the three groups. Caspase 3 was detectable both in MDS and t-AML specimens but was negligible in normal cells. The apoptotic index (AI%) determined by in situ end labeling of fragmented DNA in 4-hour cultures of mononuclear cells was significantly higher in MDS cells compared to normal or t-AML cells (mean +/- SEM: 2.3% +/- 0.4% in MDS, n = 10 vs. 0.6% +/- 0.2%, n = 4, P = 0.014 in normal cells, and 0.2% +/- 0.2%, n = 3, P = 0.007 in t-AML cells). Treatment of MDS cells with anti-Fas-L antibody suppressed apoptosis (AI%: 2.1% +/- 0.6% in untreated vs. 1.37% +/- 0.5% in treated, n = 6, P = 0.02), indicating functional participation of Fas-signaling in MDS. Further, it was found that Fas-L, Fas, and Caspase 1 mRNA expression remained unchanged in 4 hours. Caspase 3 expression appeared in normal cells after 4 hours and was present at both 0 and 4 hours in MDS and t-AML cells. In contrast to persistent expression in normal and t-AML cells, cells from the 5 MDS patients studied consistently showed significantly lowered or undetectable expression of a negative regulator of Fas, called Fas-associated phosphatase-1 (Fap-1) after 4 hours. Thus, the high AI% in MDS corresponds to a rapid decline in Fap-1. Furthermore, in tumor necrosis factor alpha (TNF-alpha) treated HL60 promyelocytic cells, a definite periodicity in the expression of different mRNAs was observed with upregulation of TNF-alpha itself at 30 minutes, increased expression of Fas and the appearance of Fas-L after 2 hours, and a decrease in Fap-1 expression after 8 hours. These results suggest that TNF-alpha not only induces the effectors of Fas-signaling but also may downregulate the inhibitor. We conclude that a spontaneous and rapid down-regulation of Fap-1, possibly induced by TNF-alpha, a cytokine shown to be present in excess in MDS marrows, may underlie the increased apoptotic death of hematopoietic cells in these patients. Interference with Fap-1 turnover may provide a new therapeutic modality for MDS.

Potassium permanganate resistant amyloid in fine-needle aspirate of the liver

A case of primary amyloidosis, initially detected by fine-needle aspiration of the liver, is reported here. Amorphous acellular metachromatic material was seen extracellularly in between the hepatocytic cords compressing them. This material showed typical apple-green birefringence under crossed bipolars after alkaline Congo-red staining proved its amyloid nature. It was resistant to potassium permanganate pretreatment, indicating it to be of the AL type.