Tara Sankar Roy

Effect of prenatal sound stimulation on medio-rostral neostriatum/ hyperstriatum ventrale region of chick forebrain: A morphometric and immunohistochemical study

The higher auditory association area in chick forebrain, i.e. medio-rostral neostriatum/hyperstriatum ventrale region (MNH), is involved in juvenile auditory filial imprinting. Studies show that neuronal size as well as expression of calcium-binding proteins, parvalbumin (PV) and calbindin D28K (CaBP) are regulated by neuronal activation. In the present study, we have determined the effect of extra auditory stimulation, given as a prenatal sound enrichment protocol, on MNH neurons of posthatch day 1 chicks. Patterned species-specific or musical (sitar) sounds were provided in a graded manner from embryonic day 10 through hatching. Thionin and immunohistochemically stained (PV and CaBP) neurons were evaluated by morphometric methods. The thionin-stained MNH neurons of both the auditory stimulated groups showed a significant increase in nuclear area compared to controls. The change in nuclear dimension was greater in the music-stimulated than in the species-specific sounds-stimulated group. These observations indicate a positive influence of prenatal sound stimulation on MNH neurons. The auditory stimulated groups also demonstrated an increase in the proportion of PV- and CaBP-neurons compared to controls, with the species-specific sounds-stimulated group showing a significantly higher percentage of immunostained cells than the music-stimulated group. However, immunostained cells of both the auditory stimulated groups did not show a significant change in size. These cytoplasmic proteins, by acting as intracellular buffers, enable neurons to display high electrical activity without calcium overload. The influx of Ca(2+) ions is essential for long-term potentiation, a phenomenon important for learning and memory. The increase in percentage of the neurons containing calcium-binding proteins may provide a morphological basis for enhancement of auditory imprinting and learning.

The aging human cochlear nucleus: Changes in the glial fibrillary acidic protein, intracellular calcium regulatory proteins, GABA neurotransmitter and cholinergic receptor.

The human auditory system is highly susceptible to environmental and metabolic insults which further affect the biochemical and physiological milieu of the cells that may contribute to progressive, hearing loss with aging. The cochlear nucleus (CN) is populated by morphologically diverse types of neurons with discrete physiological and neurochemical properties. Between the dorsal and the ventral cochlear nucleus (DCN and VCN), the VCN is further sub-divided into the rostral (rVCN) and caudal (cVCN) sub-divisions. Although, information is available on the age related neurochemical changes in the mammalian CN similar reports on human CN is still sparse. The morphometry and semiquantitative analysis of intensity of expression of glial fibrillary acidic protein (GFAP), calcium binding proteins (calbindin, calretinin and parvalbumin), gamma amino butyric acid (GABA) and nicotinic acetyl choline receptor (nAchR) beta 2 immunostaining were carried out in all three sub-divisions of the human CN from birth to 90 years. There was increased GFAP immunoreactivity in decades 2 and 3 in comparison to decade 1 in the CN. But no change was observed in rVCN from decade 4 onwards, whereas intense staining was also observed in decades 5 and 6 in cVCN and DCN. All three calcium binding proteins were highly expressed in early to middle ages, whereas a significant reduction was found in later decades in the VCN. GABA and nAchR beta 2 expressions were unchanged throughout in all the decades. The middle age may represent a critical period of onset and progression of aging changes in the CN and these alterations may add to the deterioration of hearing responses in the old age.

Differences in the cell wall architecture of melanin lacking and melanin producing Cryptococcus neoformans clinical isolates from India: an electron microscopic study

Cryptococcus neoformans e um importante fungo oportunista patogenico que causa infeccao no sistema nervoso central, e que pode levar o paciente a morte. Um dos principais fatores de virulencia do C. neoformans e a producao de melanina na parede celular. Utilizando microscopia eletronica de transmissao, nos estudamos as paredes celulares de tres pares de isolados obtidos de pacientes com dupla infeccao pelo fungo, onde um isolado melanizado e um albino foram isolados do liquor de cada paciente. A microscopia eletronica de transmissao revelou que as cepas albinas nao apresentavam a camada de melanina enquanto que uma camada de melanina estava associada com a parede celular de cepas melanoticas, constituindo aproximadamente 75% da area da parede celular. O tamanho da parede celular das celulas produtoras de melanina foi aproximadamente o dobro do tamanho da parede celular dos isolados albinos (p < 0,003). Neste estudo, a microscopia eletronica de transmissao revelou que as diferencas na estrutura dos isolados albinos sem melanina e dos isolados produtores de melanina estava associada a parede celular e a camada de melanina.

Quantitative analysis of variable extent of anterior clinoidectomy with intradural and extradural approaches: 3-dimensional analysis and cadaver dissection.

BACKGROUND: Drilling of the anterior clinoid process (ACP) is an integral component of surgical approaches for central and paracentral skull base lesions. The technique to drill ACP has evolved from pure intradural to extradural and combined techniques. OBJECTIVE: To describe the computerized morphometric evaluation of exposure of optic nerve and internal carotid artery with proposed tailored intradural (IDAC) and complete extradural (EDAC) anterior clinoidectomy. METHODS: We describe a morphometric subdivision of ACP into 4 quadrangles and 1 triangle on the basis of fixed bony landmarks. Computerized volumetric analysis with 3-dimensional laser scanning of dry-drilled bones for respective tailored IDAC and EDAC was performed. Both approaches were compared for the area and length of the optic nerve and internal carotid artery. Five cadaver heads were dissected on alternate sides with intradural and extradural techniques to evaluate exposure, surgical freedom, and angulation of approach. RESULTS: Complete anterior clinoidectomy provides a 2.5-times larger area and 2.7-times larger volume of ACP. Complete clinoidectomy deroofed the optic nerve to an equal extent as by proposed the partial tailored clinoidectomy approach. Tailored IDAC exposes only the distal dural ring, whereas complete EDAC exposes both the proximal and distal dural rings with complete exposure of the carotid cave. CONCLUSION: Quantitative comparative evaluation provides details of exposure and surgical ease with both techniques. We promote hybrid/EDAC technique for vascular pathologies because of better anatomic orientation. Extradural clinoidectomy is the preferred technique for midline cranial neoplasia. An awareness of different variations of clinoidectomy can prevent dependency on any particular approach and facilitate flexibility. ABBREVIATIONS: ACP, anterior clinoid process EDAC, extradural anterior clinoidectomy ICA, internal carotid artery IDAC, intradural anterior clinoidectomy MOB, meningo-orbital band ON, optic nerve SOF, superior orbital fissure

Practical guidelines for setting up neurosurgery skills training cadaver laboratory in India

Though the necessity of cadaver dissection is felt by the medical fraternity, and described as early as 600 BC, in India, there are no practical guidelines available in the world literature for setting up a basic cadaver dissection laboratory for neurosurgery skills training. Hands-on dissection practice on microscopic and endoscopic procedures is essential in technologically demanding modern neurosurgery training where ethical issues, cost constraints, medico-legal pitfalls, and resident duty time restrictions have resulted in lesser opportunities to learn. Collaboration of anatomy, forensic medicine, and neurosurgery is essential for development of a workflow of cadaver procurement, preservation, storage, dissection, and disposal along with setting up the guidelines for ethical and legal concerns.

Focal segmental glomerulosclerosis in idiopathic membranous glomerulonephritis: a clinico-pathological and stereological study

BACKGROUND The phenomenon of focal segmental glomerulosclerosis (FSGS) in idiopathic membranous glomerulonephritis (IMGN) has not been adequately studied. There is also a paucity of detailed glomerular morphometric and stereologic analyses data on renal biopsy in this association. METHODS Twenty-three (23) patients with IMGN and superimposed FSGS were compared to 35 patients with IMGN alone with respect to the clinical and laboratory features, light microscopic findings and stereologic parameters (glomerular cross-sectional area and estimated glomerular volume). RESULTS In the clinical parameters, patients with IMGN-FSGS had a significantly higher incidence of hypertension, raised serum creatinine and microscopic haematuria. The mean 24-h urinary protein excretion was higher in the group with IMGN-FSGS (7.4 +/- 1.36 g) as compared to IMGN alone (3.85 +/- 0.7 g, P < 0.001, Mann-Whitney test). On light microscopy, biopsies with IMGN-FSGS frequently had mesangial hypercellularity and more extensive tubulo-interstitial disease than those with IMGN alone. Stereological analysis showed that the non-sclerosed glomeruli in biopsies with IMGN-FSGS had a higher mean cross-sectional area (185466.7 +/- 32493.3 micro(2)) and higher estimated volume (855200 +/- 152640 micro(3)) as compared to glomeruli in cases with IMGN alone (76000 +/- 14719.2 micro(2) and 576666.7 +/- 131233.3 micro(3), respectively). CONCLUSION The present study is probably the first systematic analysis of stereologic parameters in renal biopsies of IMGN with FSGS. Our results objectively demonstrate the glomerular enlargement in the non-sclerosed glomeruli in cases of IMGN with FSGS. This detection of enlarged glomeruli may serve to alert the renal pathologist to the possibility of coexisting FSGS, which is a poor prognostic factor in IMGN.

Electron-microscopic evidence of mitochondriae containing macroautophagy in experimental acute pancreatitis: Implications for cell death

BACKGROUND Dysfunctional autophagy and necrosis are characteristic features of severe acute pancreatitis. OBJECTIVE To unravel the cellular mechanisms underlying the pathogenesis of acute pancreatitis. METHODS We studied the ultrastructural pancreatic morphology using electron microscopy in experimental acute pancreatitis. The control group of animals received intraperitoneal injections of normal saline. Different severity of acute pancreatitis was induced by low and high doses of caerulein in Swiss albino mice. In the low dose group, pancreatitis was induced by 4 injections of caerulein given hourly [50 μg/kg/dose - total of 200 μg/kg] and in the high dose group by 8 injections given hourly (total of 400 μg/kg). The experiments were repeated in Na-taurocholate model of acute pancreatitis in rats. The pancreatic tissue was processed and studied by transmission electron microscopy for ultrastructural changes. RESULTS The acinar cells of the pancreatitis animals revealed autophagosomes that contained cellular organelles, including mitochondria. The animals that received a higher dose of caerulein had numerous cells showing a necrotic morphology, whereas the animals in the low dose group showed a predominantly apoptotic cell morphology. The Na-taurocholate model in rats also showed similar features of severe pancreatitis with cellular necrosis and macroautophagy. CONCLUSIONS Dysfunctional mitochondria in the injured pancreatic acinar cells are degraded by macroautophagy. These observations are not model specific. Mitochondrial dysfunction and consequent energy deficit in the cells might be causally related to cellular necrosis.

Duration of injury correlates with necrosis in caerulein-induced experimental acute pancreatitis: implications for pathophysiology

Pancreatic acinar cell necrosis is indicative of severe pancreatitis and the degree of necrosis is an index of its outcome. We studied whether the dose and duration of injury correlates with severity, particularly in terms of necrosis, in caerulein‐induced acute pancreatitis (AP) in Swiss albino mice. In addition to control group 1 (G1), groups 2 and 3 received four injections of caerulein every hour but were sacrificed at five hours (G2) and nine hours (G3) respectively, and group 4 received eight injections and was sacrificed at nine hours (G4). The severity of pancreatitis was assessed histopathologically and biochemically. The histopathological scores of pancreatitis in groups 3 and 4 were significantly higher than in groups 1 and 2 (4 vs. 1, 4 vs. 2, 3 vs. 1, 3 vs. 2; P < 0.05). TUNEL‐positive apoptotic cells were significantly higher in groups 2 and 3 compared with groups 1 and 4 (P < 0.05). Necrosis was significantly more in group 4 than other groups (37.49% (4.68) vs. 19.97% (1.60) in G2; 20.36% (1.56) in G3; P = 0.006 for G 2 vs. 4 and P = 0.019 for G 3 vs. 4). Electron microscopy revealed numerous autophagosomes in groups 2 and 3 and mitochondrial damage and necrosis in group 4. The pancreatic and pulmonary myeloperoxidase activity in group 4 was significantly higher than that in the other groups (P < 0.01). Hence, severity of pancreatitis is a function of the dose of injurious agent, while inflammation is both dose and duration dependent, which may also explain the wide spectrum of severity of AP seen in clinical practice.

Variant insertion of the fibularis tertius muscle is an evidence of the progressive evolutionary adaptation for the bipedal gait

Fibularis tertius (FT) is often considered as part of extensor digitorum longus (EDL) muscle. The muscle is absent in hominoid apes and with the acquisition of the bipedal gait; the muscle emerged as a recent addition in the human foot. From its various modes of insertions, it is evident that the muscles of the sole are in search of its distal attachment, which can best support the relatively weak human midfoot. We describe an unusual insertion of the muscle in support of this hypothesis.

The human trochlear and abducens nerves at different ages - a morphometric study.

The trochlear and abducens nerves (TN and AN) control the movement of the superior oblique and lateral rectus muscles of the eyeball, respectively. Despite their immense clinical and radiological importance no morphometric data was available from a wide spectrum of age groups for comparison with either pathological or other conditions involving these nerves. In the present study, morphometry of the TN and AN was performed on twenty post-mortem samples ranging from 12-90 years of age. The nerve samples were processed for resin embedding and toluidine blue stained thin (1µm) sections were used for estimating the total number of myelinated axons by fractionator and the cross sectional area of the nerve and the axons by point counting methods. We observed that the TN was covered by a well-defined epineurium and had ill-defined fascicles, whereas the AN had multiple fascicles with scanty epineurium. Both nerves contained myelinated and unmyelinated fibers of various sizes intermingled with each other. Out of the four age groups (12-20y, 21-40y, 41-60y and >61y) the younger groups revealed isolated bundles of small thinly myelinated axons. The total number of myelinated fibers in the TN and AN at various ages ranged from 1100-3000 and 1600-7000, respectively. There was no significant change in the cross-sectional area of the nerves or the axonal area of the myelinated nerves across the age groups. However, myelin thickness increased significantly in the AN with aging (one way ANOVA). The present study provides baseline morphometric data on the human TN and AN at various ages.