Are Childhood and Adult Medulloblastomas Different? A Comparative Study of Clinicopathological Features,Proliferation Index and Apoptotic Index

Childhood medulloblastomas have been suspected to be biologically different from adult tumors, though comparative studies are sparse in the literature. The present study aims to establish any differences or nexus in the biological characteristics between childhood and adult medulloblastomas. A total of 181 medulloblastomas were studied with respect to clinical and histological characteristics, MIB-1 labeling index (MIB-1 LI), apoptotic index (AI), ratio of apoptotic to LI, p53 and Bcl-2 protein expressions. Two-thirds (112) of the 181 medulloblastomas occurred in children (15 years) and 69 in adults (>15 years). Childhood tumors were more commonly of classical histology and midline location while the desmoplastic variant and lateral location occurred more frequently in adults. Adult medulloblastomas were biologically less aggressive, having lower growth rate parameters (mean MIB-1 LI 19.1 ± 15.7; AI 3.73 ± 2.71 and AI:LI 0.207 ± 0.162) as compared to childhood tumors (mean MIB-1 LI 28.3 ± 20.4; AI 2.86 ± 2.14 and AI:LI 0.108 ± 0.111). p53 and Bcl-2 protein expressions were infrequent in all groups of tumors. No difference was noted in any of the parameters when classical and desmoplastic medulloblastomas were compared as a whole. But when compared between the age groups, an interesting observation (hitherto unreported in English literature) was that both classical and desmoplastic variants of childhood medulloblastomas had higher LI, lower AI and lower AI:LI ratio than their counterparts in adults, indicating that differences in growth rates cannot be attributed to differences in the frequency of occurrence of the histological variants in the two age groups. Thus, this study conclusively shows that there is a biological difference between childhood and adult medulloblastomas which is independent of standard histology and appeared to be associated more with age-related factors. This also warrants less-aggressive therapy for adult medulloblastoma.     

Isolation and characterization of novel oligosaccharides related to Ziracin

Five novel oligosaccharide antibiotics, Sch 58769 (1), Sch 58771 (2), Sch 58773 (3), Sch 58775 (4), and Sch 58777 (5), were isolated from the fermentation broth of Micromonospora carbonacea var africana. Their structures were determined by spectroscopic methods, including MS and (1)H and (13)C NMR experiments. A comparison of the obtained data with that for Ziracin (Sch 27899) revealed that these oligosaccharides belong to the same everninomicin family of compounds. Ziracin demonstrates potent activity against Gram-positive bacteria both in vitro and in vivo including multiply resistant strains of methicillin-resistant Staphylococcus aureus and vancomycin-resistant Enterococci faecalis.     

Accuracy of the Alberta Stroke Program Early CT Score during the first 3 hours of middle cerebral artery stroke: comparison of noncontrast CT, CT angiography source images, and CT perfusion

BACKGROUND AND PURPOSE: The Alberta Stroke Program Early CT Score (ASPECTS) is a reliable method of delineating the extent of middle cerebral artery (MCA) stroke. Our aim was to retrospectively compare the accuracy of ASPECTS on noncontrast CT, CT angiography (CTA) source images, and CT perfusion maps of cerebral blood volume (CBV) during the first 3 hours of middle cerebral artery (MCA) stroke.MATERIALS AND METHODS: First-time patients with MCA stroke who presented <3 hours from symptom onset and were evaluated by noncontrast CT/CTA/CT perfusion, had confirmed acute nonlacunar MCA infarct on diffusion-weighted MR imaging (DWI) within 7 days, and had follow-up angiography were included. Patients were excluded for persistent MCA occlusion or stenosis. Two raters through consensus assigned an ASPECTS on the noncontrast CT, CTA source images, and the section-selective (2 × 12 mm coverage) CT perfusion CBV maps. ASPECTS on follow-up DWI served as the reference standard. For each CT technique, the detection rates of regional infarction, the mean ASPECTS, and the linear correlation to final ASPECTS were determined and compared. P values <.05 were considered significant.RESULTS: Twenty-eight patients satisfied the criteria with DWI performed at a mean of 50.3 hours (range, 22–125 hours) post-CT imaging. Of 280 ASPECTS regions, 100 were infarcted on DWI. The accuracy of noncontrast CT, CTA source images, and CT perfusion CBV for detecting regional infarct was 80.0%, 84.3%, and 96.8%, respectively (P < .0001). The mean ASPECTSs of noncontrast CT, CTA source images, CT perfusion CBV, and DWI were 8.4 ± 1.8, 8.0 ± 1.8, 6.8 ± 1.9, and 6.5 ± 1.8, respectively. The mean noncontrast CT and CTA source image ASPECTS was different from that of DWI (P < .05). Correlation of noncontrast CT, CTA source images, and CT perfusion CBV ASPECTS with final ASPECTS was r² = 0.34, r² = 0.42, and r² = 0.91, respectively.CONCLUSION: In a retrospective cohort of MCA infarcts imaged <3 hours from stroke onset, ASPECTS was most accurately determined on CT perfusion CBV maps.

The Alberta Stroke Program Early CT Score (ASPECTS) is a semiquantitative method of defining infarct extent in the middle cerebral artery (MCA) territory that is more reliable than the “1/3 MCA” rule^1,2 and is highly predictive of outcome.^3-6 ASPECTS was designed for conventional noncontrast CT, the ubiquitously performed imaging technique for triaging acute stroke. However, several recent studies have reported application of ASPECTS to CT angiography (CTA) source images^7-9 and CT perfusion parametric color maps,^10-12 with data to suggest that the acute ASPECTS is more accurately determined on these advanced CT techniques. Our aim was to retrospectively compare the accuracy and strength of the correlation of the acute ASPECTSs obtained on noncontrast CT, CTA source images, and CT perfusion mapping of cerebral blood volume (CBV) for nonlacunar MCA territory strokes imaged during the initial 3 hours of symptom onset. We hypothesized that with arterial recanalization, the CT perfusion CBV map is the best predictor of the final ASPECTS.     

Dimensionality reduced plug and play priors for improving photoacoustic tomographic imaging with limited noisy data

The reconstruction methods for solving the ill-posed inverse problem of photoacoustic tomography with limited noisy data are iterative in nature to provide accurate solutions. These methods performance is highly affected by the noise level in the photoacoustic data. A singular value decomposition (SVD) based plug and play priors method for solving photoacoustic inverse problem was proposed in this work to provide robustness to noise in the data. The method was shown to be superior as compared to total variation regularization, basis pursuit deconvolution and Lanczos Tikhonov based regularization and provided improved performance in case of noisy data. The numerical and experimental cases show that the improvement can be as high as 8.1 dB in signal to noise ratio of the reconstructed image and 67.98% in root mean square error in comparison to the state of the art methods.     

Heat Treatments of Metastable β Titanium Alloy Ti-24Nb-4Zr-8Sn Processed by Laser Powder Bed Fusion

Titanium alloys, especially β alloys, are favorable as implant materials due to their promising combination of low Young’s modulus, high strength, corrosion resistance, and biocompatibility. In particular, the low Young’s moduli reduce the risk of stress shielding and implant loosening. The processing of Ti-24Nb-4Zr-8Sn through laser powder bed fusion is presented. The specimens were heat-treated, and the microstructure was investigated using X-ray diffraction, scanning electron microscopy, and transmission electron microscopy. The mechanical properties were determined by hardness and tensile tests. The microstructures reveal a mainly β microstructure with α″ formation for high cooling rates and α precipitates after moderate cooling rates or aging. The as-built and α″ phase containing conditions exhibit a hardness around 225 HV5, yield strengths (YS) from 340 to 490 MPa, ultimate tensile strengths (UTS) around 706 MPa, fracture elongations around 20%, and Young’s moduli about 50 GPa. The α precipitates containing conditions reveal a hardness around 297 HV5, YS around 812 MPa, UTS from 871 to 931 MPa, fracture elongations around 12%, and Young’s moduli about 75 GPa. Ti-24Nb-4Zr-8Sn exhibits, depending on the heat treatment, promising properties regarding the material behavior and the opportunity to tailor the mechanical performance as a low modulus, high strength implant material.     

Investigating the Efficacy of Adhesive Tape for Drilling Carbon Fibre Reinforced Polymers

In the present research work, an effort has been made to explore the potential of using the adhesive tapes while drilling CFRPs. The input parameters, such as drill bit diameter, point angle, Scotch tape layers, spindle speed, and feed rate have been studied in response to thrust force, torque, circularity, diameter error, surface roughness, and delamination occurring during drilling. It has been found that the increase in point angle increased the delamination, while increase in Scotch tape layers reduced delamination. The surface roughness decreased with the increase in drill diameter and point angle, while it increased with the speed, feed rate, and tape layer. The best low roughness was obtained at 6 mm diameter, 130° point angle, 0.11 mm/rev feed rate, and 2250 rpm speed at three layers of Scotch tape. The circularity error initially increased with drill bit diameter and point angle, but then decreased sharply with further increase in the drill bit diameter. Further, the circularity error has non-linear behavior with the speed, feed rate, and tape layer. Low circularity error has been obtained at 4 mm diameter, 118° point angle, 0.1 mm/rev feed rate, and 2500 RPM speed at three layers of Scotch tape. The low diameter error has been obtained at 6 mm diameter, 130° point angle, 0.12 mm/rev feed rate, and 2500 rpm speed at three layer Scotch tape. From the optical micro-graphs of drilled holes, it has been found that the point angle is one of the most effective process parameters that significantly affects the delamination mechanism, followed by Scotch tape layers as compared to other parameters such as drill bit diameter, spindle speed, and feed rate.     

Nager acrofacial dysostosis: An unusual association with both upper and lower eyelid colobomas

Nager acrofacial dysostosis comprises defects of cranio facial region and limbs (mostly upper) with variable associated anomalies. The cranio-facial complex is indistinguishable from the mandibulo facial dysostosis (Treacher Collins syndrome). About 80 cases have been described in the literature. We describe the case of a one-day-old male neonate who presented with the typical features of the disease complex. Although normal life span has been reported, our patient died on the second day due to cardio respiratory failure. We report this case because of its rarity and an unusual associated feature of bilaterally symmetrical upper and lower eyelid colobomas.     

Larval habitats and species composition of mosquitoes in Darjeeling Himalayas, India

BACKGROUND & OBJECTIVES: A preliminary survey of larval mosquito habitats and temporal variation in mosquito diversity in the hill town of Darjeeling, India was made during 2003, for a qualitative and quantitative assessment of mosquito distribution. METHODS: The possible larval habitats of mosquitoes were surveyed and the species diversity in the sites positive for mosquito larvae was noted. Bi-weekly sampling from a particular habitat was carried out to reveal the temporal variation in mosquito species. RESULTS: A good number of lentic aquatic habitats were found to be hosting mosquito immatures, though difference in the physical and biological features of these habitats was prominent. Altogether, immatures of six mosquito species, belonging to four genera--Aedes, Armigeres, Culex and Toxorhynchites were noted with significant difference in temporal variation in their relative and absolute numbers. A positive correlation (r = + 0.707) was found between population of the prey mosquito immatures and the population of immatures of Tx. splendens. The species diversity index (H') for the mosquitoes remained between 0.87 and 1.53. The evenness components ranged between 54.03 and 95.03% and differed significantly. INTERPRETATION & CONCLUSION: In the present study, the aquatic bodies could be categorised into six types depending on the size and structural complexity that may account for the observed variation in the species composition of the larval habitats. In addition to this, other factors like temperature, rainfall and other related climatic attributes may be responsible for the observed species variation, which needs to be confirmed through further studies.