A Survey of Knowledge and Attitude of College Students Toward Hearing Loss Prevention.

BACKGROUND: College students risk hearing loss due to loud sound exposure during leisure activities. Hearing loss prevention is possible by reducing the noise from the source, using hearing protection devices and increasing their knowledge and awareness on the effects of loud sound exposure. OBJECTIVE: The study aims to assess the knowledge and attitude of college students regarding hearing loss and its prevention. STUDY DESIGN: A cross-sectional study design with a survey method was adopted. A total of 94 college students (mean age: 22 years; range: 18 to 26) who were pursuing an undergraduate and postgraduate degree (50 males and 44 females) formed the part of the study. The researcher administered a standardized self-reported Knowledge, Attitude and Behaviour questionnaire. The knowledge score in percentage and absolute scores for attitude were estimated. RESULTS: The mean knowledge score was 35.8 (SD ± 12.18; range: 12.5-75), and the attitude score was + 9.8 (SD ± 7.1; range: - 4 to + 30). Chi square test revealed no significant association between knowledge and attitude to sociodemographic characteristics. CONCLUSION:  The study indicated that though college students lack knowledge, they had a positive attitude regarding hearing health and its protection. These findings implicate the importance of creating awareness and encouraging hearing protection strategies for college students.

Degenerated lumbricals in the feet of adult human cadavers: case series.

In the foot, the lumbricals flex the metatarsophalangeal joints and extend the interphalangeal joints. The lumbricals are known to be affected in neuropathies. It is not known whether they may degenerate in normal individuals. Here, we report our findings of isolated degenerated lumbricals in seemingly normal feet of two cadavers. We explored lumbricals in 20 male and 8 female cadavers that were 60-80 years of age at the time of death. As part of routine dissection, we exposed the tendons of the flexor digitorum longus and the lumbricals. From the degenerated lumbricals, we took some tissue for paraffin-embedding, sectioning, and staining by hematoxylin and eosin, and Masson's trichrome technique. Of the 224 lumbricals studied, we found four apparently degenerated lumbricals in two male cadavers. In the first, the 2nd and 4th lumbricals in the left foot and the 2nd in the right foot were degenerated. In the second, the right 4th lumbrical was degenerated. Microscopically, the degenerated tissue was made of bundles of collagen. The lumbricals may have degenerated due to compression of their nerve supply. We cannot comment on whether the functionality of the feet were affected by these isolated degeneration of the lumbricals.

Nerve fibre morphometry with transmission electron microscopy: Application of the nucleator probe in ImageJ.

Stereology and semiautomated binary image histomorphometry are two common methods used for morphometry of nerve fibres. Nucleator probe can be used for the estimation of morphometric parameters like diameter, perimeter, area and volume of a structure that is approximately either a circle or a sphere. In this study, we estimated these parameters with the help of ImageJ software on calibrated transmission electron micrographs. We procured samples of the cochlear nerve (CN) during winter months, within 6-12 hours of death, to reduce post-mortem autolytic changes. The temporal bones containing the CN were fixed by immersion in chilled paraformaldehyde. After dissecting out from the petrous part of the temporal bone, the CN were osmicated and processed for embedding in resin. From the resin blocks, silver coloured (70 nm) ultrathin sections were cut and picked on 300-mesh copper grids, stained with uranyl acetate and lead citrate and viewed under Tecnai G2-20 transmission electron microscope. The transmission electron micrographs had scale bars embedded into them by the software at the time of imaging, and the morphometric parameters of randomly selected nerve fibres were measured using the ImageJ software. The ImageJ software could become a low-cost and dependable tool for nerve fibre morphometry.•Nucleator probe is used for the estimation of morphometric parameters like diameter, perimeter, area or volume•Morphometric parameters were estimated by the ImageJ software on calibrated transmission electron micrographs•The ImageJ software could become a low-cost and dependable tool for nerve fibre morphometry.

The ultrastructural study of human cochlear nerve at different ages.

Ultrastructural and molecular changes in the myelin of the cochlear nerve (CN) have been associated with decreased hearing-acuity with increasing age. But most of these are animal studies or with very few human samples. Hence, we studied the ultrastructure of the human CN at different ages. We obtained samples of CN from persons, who at the time of death belonged to young, middle or old age-groups; defined as ≤ 30, 31 to 50, and ≥ 51 years of age, respectively. These were processed for viewing under a transmission electron microscope (TEM). Morphology and morphometry were assessed after blinding the observer. Measurements of diameter (whole nerve fibre, axon), myelin thickness and calculation of G-ratio were made on calibrated images using ImageJ software. K-Means cluster analysis was performed based on total and inner nerve fibre area. Middle and old age CN showed degenerating axons, splitting of myelin sheath and myelin balloons. Between the middle and old age groups there was significant decrease in axon diameter (p<0.001), inner nerve fibre area (p<0.001), myelin thickness (p<0.001), nerve fibre diameter (p<0.001), and G-ratio (p<0.001). By clustering, we identified three distinct populations of myelinated nerve fibres: large, medium and small. The large fibres (by size), seen in the young, disappeared in the old age-group. We were unable to find any unmyelinated nerve fibres in this study. The morphological deterioration CN fibres may be a visible sign of molecular degeneration and contribute to decreased hearing-acuity.

Femoral Intercondylar Notch: Gross Anatomy and Histology of the Connective Tissue Lining of its Roof: A Pilot Study.

PURPOSE: We have consistently observed a connective tissue lining over the intercondylar notch's roof (CTLINR) during arthroscopic surgeries of the knee joint. As there is a strong association of the intercondylar fossa with the anterior cruciate ligament (ACL), we believe that this tissue must be having some role in the functioning of the ACL. The purpose of this pilot study was to investigate the anatomic characteristics of the CTLINR. METHODS: In this observational anatomical study, we have investigated the gross anatomical and histological features of the CTLINR in four knees of two fresh frozen non-embalmed cadavers. We have also studied its ultrastructural characteristics by obtaining an arthroscopic biopsy of the tissue from a patient undergoing ACL reconstruction. RESULTS: At gross examination, the CTLINR had a typical glistening white surface with transversely oriented fibres. It entirely covered the roof of the intercondylar notch and was soft to touch. Histological examination with haematoxylin-eosin stain revealed fibro-collagenous tissue with intervening blood vessels. Transmission electron microscopy manifested loosely arranged collagen fibres of variable diameter. CONCLUSION: The histological and electron microscopic characteristics of the tissue differentiate it from the ACL and its femoral enthesis, suggesting that it was a distinct anatomical structure. As it entirely covered the roof of the intercondylar fossa and had a smooth surface and soft consistency, it may protect the reconstructed ACL from graft abrasion. Furthermore, as it had a characteristic arthroscopic appearance, future research can investigate its role in femoral tunnel positioning.

Co-administration of nalbuphine attenuates the morphine-induced anxiety and dopaminergic alterations in morphine-withdrawn rats.

INTRODUCTION: The classical effects of exogenous opioids, such as morphine, are predominantly mediated through µ-opioid receptors. The chronic use of morphine induces anxiety-like behavior causing functional changes in the mesolimbic dopaminergic system. The mixed µ/κ-agonist, nalbuphine, used either as an analgesic or as an adjuvant with morphine, produces different and opposite effects. However, whether nalbuphine can be used to antagonize morphine-induced anxiety and dopaminergic alterations is not fully known. OBJECTIVE: This study aimed to compare acute and chronic effects of nalbuphine on morphine-induced anxiety and dopaminergic alterations in rats. METHODS: Male adult Wistar albino rats were made opioid-dependent by administering increasing doses of morphine (5-25 mg/kg; i.p.; b.i.d.). Withdrawal was induced by naloxone (1 mg/kg, i.p.), 4 h after the last morphine injection. Anxiety-like behavior was measured using Activity Monitor (Coulbourn Instruments, Inc. USA). Thereafter, the animals were sacrificed and the brain dissected out and the level of cAMP and the transcriptional and translational expression of TH was measured. Nalbuphine was co-administered with morphine, acutely and chronically, at various doses (0.1, 0.3, 1.0, 3.0 mg/kg, i.p.). RESULTS: Morphine-dependent rats showed a significant higher anxiety and cAMP levels and a significant decrease in the expression of TH. Co-administration of chronic doses of nalbuphine attenuates the higher anxiety, cAMP levels, and upregulates the TH expressions; however, the acute nalbuphine treatment does not attenuate the morphine-induced side effects. CONCLUSION: Therefore, nalbuphine might have an important role in attenuating the anxiety and the effects of the dopaminergic pathway and may have potential in the treatment of opioid addiction.

Biocompatibility analysis of PLA based candidate materials for cardiovascular stents in a rat subcutaneous implant model.

Modification of Polylactic acid (PLA), a biopolymer, is a strategy still to be fully explored for the next generation of bioresorbable vascular stent (BVS) biomaterials. With this focus, inclusions upto 5% of Polycaprolactone (PCL) and Magnesium in PLA were tested in the rat subcutaneous model and their cellular and tissue interactions characterized, specifically with respect to inflammatory response, angiogenesis and capsularization. The cytokines IL6, TNF Alpha and IL-1Beta were estimated in the peri-implant tissue, all of which showed a non-significant difference between the non-implanted animals and those containing PLA by 8 weeks, speaking to the benign nature of PLA as an implant biomaterial. Both modified materials, had increased macrophage counts and cytokine levels, except IL6 at 8 weeks. Vascularization only at 8 weeks in PLA PCL containing tissue was significantly higher than pure PLA, which may be more carefully controlled along with the material hydrophobicity for possible efforts towards therapeutic angiogenesis. Capsule thickness, measured by staining with both Hematoxylin & Eosin and Masson's Trichome did not show any differences between materials, including PLA.

Recommendation of a practical guideline for safe tracheostomy during the COVID-19 pandemic.

PURPOSE: The COVID-19 pandemic is placing unprecedented demand upon critical care services for invasive mechanical ventilation. There is current uncertainty regarding the role of tracheostomy for weaning ventilated patients with COVID-19 pneumonia. This is due to a number of factors including prognosis, optimal healthcare resource utilisation, and safety of healthcare workers when performing such a high-risk aerosol-generating procedure. METHODS: Literature review and proposed practical guideline based on the experience of a tertiary healthcare institution with 195 critical care admissions for COVID-19 up until 4th April 2020. RESULTS: A synthesis of the current international literature and reported experience is presented with respect to prognosis, viral load and staff safety, thus leading to a pragmatic recommendation that tracheostomy is not performed until at least 14 days after endotracheal intubation in COVID-19 patients. Practical steps to minimise aerosol generation in percutaneous tracheostomy are outlined and we describe the process and framework for setting up a dedicated tracheostomy team. CONCLUSION: In selected COVID-19 patients, there is a role for tracheostomy to aid in weaning and optimise healthcare resource utilisation. Both percutaneous and open techniques can be performed safely with careful modifications to technique and appropriate enhanced personal protective equipment. ORL-HNS surgeons can play a valuable role in forming tracheostomy teams to support critical care teams during this global pandemic.

Age-related changes in the number of cresyl-violet-stained, parvalbumin and NMDAR 2B expressing neurons in the human spiral ganglion.

Animal-studies associate age-related hearing loss (presbycusis) with decreasing number of spiral ganglion neurons (SGNs) in Rosenthal's canal (RC) of cochlea. The excitatory neurotransmitter for SGNs is glutamate (through its receptor NMDAR 2B), which can be neurotoxic through Ca2+ overload. Neurotoxicity is balanced by calcium-binding proteins (CBPs) like Parvalbumin (PV), which is the predominant CBP of the SGNs. To estimate the volume of the RC and total number of SGNs that are immunoreactive to PV and NMDAR 2B, we used unbiased stereology in 35 human cochleae derived from cadavers of persons from 2nd to 8th decade of life (subsequently statistically divided into two groups) and compared them to the total number of cresyl violet (CV) stained SGNs. We also estimated the volume of individual neurons and their nuclei. Regression analysis was made on estimated parameters against age. Hierarchical-cluster analysis was done on the neuronal against neuronal nuclear volumes.The average volume of the RC did not change with increasing age (p = 0.4115). The total number of SGNs (CV-stained and those separately expressing PV and NMDAR 2B) significantly decreased with age (p < 0.001). We identified three distinct populations of neurons on the basis of their volumes among SGNs. Thus, there is significant age-related decline in the total number of SGNs, which starts early in life. It may be due to ambient noise and inadequate neutralisation of excitotoxicity.

An in vitro Comparative Evaluation of Volume of Removed Dentin, Canal Transportation, and Centering Ratio of 2Shape, WaveOne Gold, and ProTaper Gold Files Using Cone-Beam Computed Tomography.

OBJECTIVES: The aim of this study was to compare the shaping ability of three file systems - 2Shape (2S), WaveOne Gold (WOG), and ProTaper Gold - using cone-beam computed tomography (CBCT). MATERIALS AND METHODS: Forty-five freshly extracted mandibular teeth were chosen and instrumented using the following brands of NiTi files: 2S, WOG, and ProTaper Gold. Pre- and post-instrumentation CBCT imaging was performed to measure mesial and distal distance of the dentin walls and calculate the volume of removed dentin, apical transportation, and centering ratio. A statistical analysis of the data was performed using independent t-test. Statistical significance was set at 5%. RESULTS: There were no significant differences between the 2S and WOG in terms of the total volume of removed dentin, apical transportation, and centering ratio, whereas ProTaper showed a greater significant difference when compared to 2S and WOG. CONCLUSION: Both 2S and WOG maintained the original canal anatomy better and did not remove excess dentin while chemomechanical preparation as compared to ProTaper Gold. Instruments that use rotary movement achieved an effect similar to that of the reciprocating instruments in relation to change in angle. 2S which is a two-file system and WOG which is a single-file system might perform better clinically and might show enhanced shaping ability with less canal transportation and more centered preparation when compared to ProTaper Gold that is a multiple file-system.

Morphological development of the human cochlear nucleus.

Morphological studies in developing brain determine critical periods of proliferation, neurogenesis, gliogenesis, and apoptosis. During these periods both intrinsic and extrinsic pathological factors can hamper development. These time points are not available for the human cochlear nucleus (CN). We have used design-based stereology and determined that 18-22 weeks of gestation (WG) are critical in the development of the human CN. Twenty-three fetuses and seven postnatal brainstems were processed for cresyl violet (CV) staining and immunoexpression of NeuN (neurons), GFAP (astrocytes), Ki-67 (proliferation) and TUNEL (apoptosis) and 3-D reconstruction. The volume of CN, total number of neurons selected profiles and the volume of neurons and their nuclei were estimated. Data were grouped (G) into: G1:18-20 WG, G2: 21-24 WG, G3: 25-28 WG and G4 >29 WG. The dimensions of morphologically identified neurons were also measured. The CN primordium was first identifiable at 10WG. Definitive DCN (Dorsal cochlear nucleus) and VCN (ventral cochlear nucleus) were identifiable at 16 WG. There was a sudden growth spurt in total volume of CN, number of neurons and astrocytes from 18 WG. We also observed an increase in proliferation and apoptosis after 22 WG. The number of neurons identifiable by CV was significantly lower than that by NeuN-immunostaining till 25 WG (p = 0.020), after which, both methods were equivalent. Eight morphological types of neurons were identifiable by 26 WG and could be resolved into four clusters by volume and diameter. The CN changed orientation from small, flat and horizontal at 10-16 WG to larger and oblique from 18WG onwards. Prevention of exposure to noxious factors at 18-22 WG may be important in preventing congenital deafness.

Estimation of Volume of Stria Vascularis and the Length of Its Capillaries in the Human Cochlea.

BACKGROUND: The stria vascularis (SV) is a vascularized epithelium that secretes endolymph and is located on the lateral wall of the membranous cochlea. The capillaries of SV directly influence the composition of the endolymph and hence the generation of impulses by the hair-cells that are auditory receptors and thus affect hearing. Therefore, the real morphology of the SV would be very important for understanding the hearing system. There are few reliable reports of the morphology of the human SV. AIMS AND OBJECTIVES: In this research, we have estimated the volume of the SV and total length of strial capillaries in the apical, middle and basal turns of the human cochlea by updated stereological techniques. METHODS: The point-counting Cavalieri's method and hemispherical volume probes were applied on stained, 40 µm-thick serial sections of five celloidin-embedded, decalcified cochleae. RESULTS: The mean age of persons at the time of death was 51 ± 15.25 years, the mean volume of the SV was 0.56 ± 0.054 mm3 and the mean length of the SV capillaries was 289.08 ± 72.96 mm. We also estimated the same parameters with different stereological parameters, probes and in differently stained sections and checked the relationship and limits of agreement between different methods by paired t-test and Bland-Altman plot. We found agreement in our results. CONCLUSION: We provide reliable baseline data on the real morphology of the human SV.

Morphological and neurochemical changes in GABAergic neurons of the aging human inferior colliculus.

It is well known that quality of hearing decreases with increasing age due to changes in the peripheral or central auditory pathway. Along with the decrease in the number of neurons the neurotransmitter profile is also affected in the various parts of the auditory system. Particularly, changes in the inhibitory neurons in the inferior colliculus (IC) are known to affect quality of hearing with aging. To date, there is no information about the status of the inhibitory neurotransmitter GABA in the human IC during aging. We have collected and processed inferior colliculi of persons aged 11-97 years at the time of death for morphometry and immunohistochemical expression of glutamic acid decarboxylase (GAD67) and parvalbumin. We used unbiased stereology to estimate the number of cresyl-violet and immunostained neurons. Quantitative real-time PCR was used to measure the relative expression of the GAD67 mRNA. We found that the number of total, GABAergic and PV-positive neurons significantly decreased with increasing age (p < 0.05). The proportion of GAD67-ir neurons to total number of neurons was also negatively associated with increasing age (p = 0.004), but there was no change observed in the proportion of PV-ir neurons relative to GABAergic neurons (p = 0.25). Further, the fold change in the levels of GAD67 mRNA was negatively correlated to age (p = 0.024). We conclude that the poorer quality of hearing with increasing age may be due to decreased expression of inhibitory neurotransmitters and the decline in the number of inhibitory neurons in the IC.

Development of a Novel Technique to Dissect the Mesentery That Preserves Mesenteric Continuity and Enables Characterization of the ex vivo Mesentery.

Introduction: The conventional model of abdominal anatomy described multiple mesenteries. Dissection techniques were based on this. Recent studies demonstrate the mesentery is continuous from duodenojejunal flexure to anorectal junction. Given this, it is important to update dissection techniques related to the mesentery in the cadaveric setting. Materials and Methods: A technique of mesenteric dissection was developed and tested in a cohort of 20 adult human cadavers (12 male and 8 female). As the technique enabled excision of the mesentery as a single unit, it was possible to characterize the anatomy of the ex vivo mesentery. Results: The technique developed enabled dissection of an intact and continuous mesentery in all cadavers examined. Examination of the ex vivo mesentery demonstrated that a mesoduodenum was present in all cases. The mesentery was continuous from the mesoduodenum to the mesorectum and ended at the level of the anorectal junction. Conclusions: A technique was developed that reproducibly enabled dissection of an intact and continuous mesentery from the duodenum to the anorectal junction. A mesoduodenum was consistently observed and noted to be in continuity with the remainder of the mesentery.

Ultrastructural Study of Rat Testis Following Conventional Phototherapy during Neonatal Period.

INTRODUCTION: Phototherapy is the most common treatment for neonatal jaundice. This study sought to determine ultrastructural changes in testis, at different time-points, after 48 hours of conventional phototherapy was given to newborn rats. METHODS: Newborn male Wistar rats (n = 36) were divided into two groups as follows - group 1 (G1), control (without phototherapy) and group 2 (G2), exposure to conventional phototherapy for 48 h. Six animals from each group were sacrificed on postnatal days (PND) 70, 100 and 130. The testes were dissected out and processed for Transmission Electron Microscopy (TEM). RESULTS: TEM showed that G2 on PND 70 and 100 showed damaged organelles, including nuclei, mitochondria, endoplasmic reticulum, vacuoles and electron dense bodies in the testes. Seminiferous Tubule on PND130 showed lesser damage. On PND70 ST wall thickness (STWT) of G2 was significantly higher (P < 0.001) than G1 STWT of G2 was significantly lower than G1 on PND100 (P = 0.047) and on PND130 (P < 0.001). Mitochondrial diameter in spermatogonia was significantly higher in G2 on PND70 (P = 0.001), PND100 (P = 0.031) and PND130 (P = 0.028). Primary spermatocytes in G2 also had larger mitochondria on PND70 (P < 0.001), PND100 (P = 0.007) and PND130 (P = 0.008). Further, spermatids had larger mitochondria in G2 on PND70 (P < 0.001), PND100 (P = 0.044) and PND130 (P < 0.001). CONCLUSION: Phototherapy causes degenerative changes in rat testis on PND70 and 100 that partially recover by PND 130.

Interleukin-6 significantly improves predictive value of systemic inflammatory response syndrome for predicting severe acute pancreatitis.

BACKGROUND: Predicting severe acute pancreatitis (AP) is important for triage, prognosis, and designing therapeutic trials. Persistent systemic inflammatory response syndrome (SIRS) predicts severe AP but its diagnostic accuracy is suboptimal. Our objective was to study if cytokine levels could improve the predictive value of clinical variables for the development of severe AP. METHODS: Consecutive patients with AP were included in a prospective cohort study at a tertiary care center. Serum levels of IL-6, TNF-α, IL-10, MCP-1, GM-CSF and IL-1ß were measured at day 3 of onset of AP. Variables such as age, co-morbidity, etiology, SIRS, and cytokines were modeled to predict severe AP by multivariable regression analysis. Genotyping was done to correlate IL-6, TNF-α and MCP-1 gene polymorphisms with cytokine levels. RESULTS: Of 236 patients with AP, 115 patients admitted within 7 days of onset formed the study group. 37 of the 115 (32%) patients developed organ failure. Independent predictors of organ failure were persistent SIRS (OR 34; 95% CI: 7.2-159) and day 3 serum IL-6 of >160 pg/ml (OR 16.1; 95% CI:1.8-142). IL-6 gene (-174 G/C) GG genotype was associated with significantly higher levels of IL-6 compared to CC/CG genotype. Serum IL-6 >160 pg/ml increased the positive predictive value of persistent SIRS from 56% to 85% and specificity from 64% to 95% for predicting OF without compromising its sensitivity and negative predictive value. CONCLUSION: Serum IL-6 of >160 ng/ml added significantly to the predictive value of SIRS for severe AP.

Aberrant Cutaneous Nerve Loops in the Axilla.

During routine dissection classes, conducted for first year undergraduate medical students, we encountered a rare anatomical variation in relation to the intercostobrachial nerve (ICBN). The ICBN represents the lateral undivided cutaneous branch of second intercostal nerve. In this case, the ICBN formed nerve loops with branches of the lateral cutaneous branch of the third intercostal nerve. These loops eventually gave branches that probably supplied the floor of the axilla and proximal arm. Nowadays, this ICBN is gaining clinical importance during the axillary lymph node dissections and mammary gland surgeries. Damage to the ICBN, may results in the sensory deficits in patients undergoing surgery. In our case report, ICBN was making aberrant nerve loop along with the branches from the third intercostal nerve. Knowledge regarding the origin, formation and route of ICBN is of clinical significance to axillary surgeons, radiologist and anesthesiologists.

Unique cardiac anomaly due to lateralization of a straight trunco-conal septum

Congenital heart disease is present in 4-50/1000 live births worldwide, causing about 10% of infant mortality. Congenital heart disease arises when there is a defect in the process of development of the heart through looping, remodeling, realignment and septation of the primitive endothelial tube. Here we describe a case of congenital heart disease where there was formation of straight truncoconal septum with lateralization. It has caused transposition of great vessels, atretic non communicating stenosed pulmonary trunk, and blind outflow tract of left ventricle. There was renal anomaly too in the form of horseshoe kidney. The entire developmental anomaly could be traced back to the period between the 6th and the 9th week of intrauterine life. The neonate died within half an hour of birth

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