OBJECTIVE The authors aimed to assess the frequency of homozygous CDKN2A deletion in isocitrate dehydrogenase (IDH)–mutant diffuse astrocytomas (grade 2/3) and to narrow down the clinicopathological indications in which the CDKN2A fluorescence in situ hybridization (FISH) assay is cost-effective in resource-constrained settings. METHODS IDH-mutant astrocytomas were analyzed for ATRX, p53, MIB1-LI, and p16 expression using immunohistochemistry. The FISH assay was used to evaluate CDKN2A deletion and 1p/19q codeletion. Survival outcomes were assessed according to the different molecular markers. RESULTS A total of 150 adult patients with IDH-mutant grade 2 (n = 95) and grade 3 (n = 55) astrocytomas (145 primary and 5 recurrent) were analyzed. Using a cutoff value of 30% for defining significant homozygous CDKN2A deletion, none of the grade 2 and 10.9% (6/55) of grade 3 astrocytomas showed this deletion (4 primary and 2 recurrent grade 3 tumors) and were reclassified as grade 4. This mutation was more frequent in recurrent (40%, 2/5) than primary (2.76%, 4/145) gliomas. Half (3/6, 50%) of the CDKN2A-deleted cases demonstrated poor outcomes; 2 of these cases experienced recurrence at 12 and 36 months after surgery, and 1 died at 5 months. The majority of CDKN2A-deleted cases showed marked cellularity (100%), pleomorphism (100%), brisk mitosis (83.3%), and tumor giant cell formation (83.4%). None of the cases with retained p16 expression harbored this deletion. Both overall survival (p = 0.039) and progression-free survival (p = 0.0045) were found to be worse in cases with p16 loss. Selectively performing CDKN2A FISH only in high-risk cases with histomorphological features of anaplasia, p16 loss, or recurrent tumors achieved a sensitivity and negative predictive value of 100%. This approach would have resulted in saving 41.1% of the original expenditure ($6900 US per 150 samples) and 27.6 person-minutes per sample without compromising the identification of deleted cases. CONCLUSIONS Homozygous CDKN2A deletion is conspicuously absent in grade 2 and rare in primary grade 3 IDH-mutant astrocytomas. The authors propose that restricting use of the FISH assay to cases showing histomorphological features of anaplasia, p16 loss, or recurrent tumors will help this platform to be utilized in the most cost-effective manner in resource-constrained settings.

Background: A confirmatory diagnosis of tuberculoid (TL) and borderline TL (BTL) leprosy is dependent on the demonstration of nerve involvement within granuloma or acid-fast bacilli. It is very difficult to identify nerve elements in hematoxylin and eosin (H&E) stains. S-100 stain in this study is used to highlight nerve in TL leprosy so as to reach a definitive diagnosis of TL leprosy. Aim and Objectives: The aim of the study was to demonstrate nerve involvement and various changes of nerves in different forms of leprosy and use of S-100/or confirmation of TL leprosy/BTL leprosy. Materials and Methods: Skin biopsies of a total of 53 cases of leprosy were studied. The study is conducted in the department of pathology, HIMS, Safedabad, Barabanki U.P. The present study included all the new leprosy patients visiting the outpatient department of Skin and V.D, department, HIMS, Safedabad, Barabanki, U.P. Study period was 2015–2016 (1 year). All biopsies were studied in H&E stain. Biopsies were further subjected to S-100 stain so as to make a confirmatory diagnosis of TL leprosy/BTL and were then classified according to Ridley-Jopling classification only histological parameters of classification were used in this study. Results: In the present study, it was observed that the majority of patients were between the ages of 31 and 40 years (39.5%), males were mostly affected (10.5%), and family history was positive (8.4%). Hypopigmented skin lesion was the most common clinical lesion (31.2%).TT was the most common clinical diagnosis (25.4%). IL was the most common histopathological diagnosis (26.1%). The nerve changes were demonstrated in TL/BTL leprosy using S-100 immunostain. It was observed that the most of the cases of TL/BTL demonstrated fragments of nerves that were infiltrated by lymphocytes. This was the most common pattern seen among the patients of TL/BTL leprosy. Complete nerve was not identified in any of the cases. Conclusions: S-100 immunostain simplified detection of nerve twigs in TL/BTL leprosy. It was also seen that the most of the fragmented nerve elements were present within the granulomas. The TL spectrum of leprosy significantly affected nerves and using S-100 helped in differentiating it from other forms of leprosy.

The need for renewable energy sources is on the rise because of the acute energy crisis in the world today. This describes the design, optimization, and evaluation of the power electronics circuitry for a low-power portable thermophotovotaic (TPV) generator system in mat lab. TPV system is based on a silicon micro-reactor design and low-band gap photovoltaic (PV) diodes. We outline critical system-level challenges associated with TPV power generation, and propose a power electronics architecture that addresses these challenges. We present experimental data from a compact, highly efficient peak power tracker and show how the proposed architecture enables increased energy extraction compared to conventional methods. The operation of the power tracker is verified with low-band gap PV cells illuminated by a quartz halogen lamp producing a PV diode output power of 0.5 W, and above 99% tracking efficiency is demonstrated. Additionally, the complete system operation is verified with the power tracker connected to GaInAsSb PV diodes silicon and a micro-reactor, producing 150 mW of electrical power.

No abstract