Alveolar rhabdomyosarcoma in children with histomorphological review.

Rhabdomyosarcomas (RMS) are aggressive malignant neoplasm of mesenchymal origin, related to skeletal muscle lineage. These are the most common soft tissue tumors in children. The diagnosis is made by microscopic analysis and ancillary techniques like immunohistochemistry, electron microscopy, cytogenetics and molecular biology. We encountered a case of a 03 years old child who presented with a tender, reddish, soft swelling over cheek for three weeks. The FNAC was reported as a small round cell tumor, Probably Primitive Neuroectodermal Tumor (PNET). The biopsy of tumor revealed a small round cell tumor with an alveolar pattern. Tumor giant cells were absent and mitotic figures were infrequent. Hence, differentials of alveolar rhabdomyosarcoma and PNET were rendered. Immunohistochemistry (IHC) demonstrated desmin positivity. Thus, a final diagnosis of alveolar rhabdomyosarcoma was offered.

Regional metabolism of 5-hydroxytryptamine in brain under acute and chronic heat stress.

The metabolic alteration of 5-HT in four different regions of rat brain and plasma was studied under acute and chronic heat stress. A generalised elevation of 5-HT in all the brain regions along with high plasma level was observed in animals subjected to 4 hour heat stress at 38 degrees C. Such elevation of brain 5-HT may be due to entry of plasma 5-HT into the brain owing to breakdown of blood-brain barrier (BBB). In heat adapted rats, where BBB remained unaffected, no increase in brain 5-HT was observed, rather a significantly low level was maintained both in plasma and brain tissue.

Role of 5-HT on increased permeability of blood-brain barrier under heat stress.

Exposure of young rats (9-10 wks) to chronic summer heat (36 degrees C) or acute heat (38 degrees C 4hr) increased the BBB permeability to Evans blue albumin complex (MW 68,000) and 131I-sodium (MW 154) in different brain regions which correlated well with the increased level of 5-HT in plasma and brain. This increased permeability of BBB and the increased 5-HT level were prevented by pretreatment with p-CPA, indomethacin and diazepam. Cyproheptadine and vinblastine pretreatment however, prevented only the increased permeability of BBB, the plasma and brain 5-HT level continued to remain high. These results indicate a probable role of 5-HT as one of the factors leading to the increased permeability of BBB in young rats following heat stress.

Influence of ambient temperature and drug treatments on brain oedema induced by impact injury on skull in rats.

The progression and persistence of oedema development following impact-injury on closed skull was studied in anaesthetised as well as in unanaesthetised rats. The degree and rate of oedema development, following trauma, was aggravated in anaesthetised hypothermic animals but was reduced/or delayed by maintenance of body temperature at euthermic level. In general, the unanaesthetised animals showed a greater accumulation of oedema fluid than the corresponding anaesthetised group. The development of oedema corresponded more or less with the accumulation of 5-HT level in plasma and brain. This development of oedema was completely prevented following pretreatment with p-CPA, indomethacin paracetamol and aminophylline in unanaesthetised animals; whereas these drugs were able only to partially reduce the oedema development in euthermic anaesthetised animals. On the other hand the cyproheptadine pretreatment aggravated the oedema development which was more pronounced in unanaesthetised animals. The probable mechanism of the action of these drugs has been discussed.

Impairment of blood-brain barrier (BBB) in rat by immobilization stress: role of serotonin (5-HT).

Influence of immobilization stress on blood-brain barrier (BBB) was studied in rats using Evans blue as barrier tracer. 7-9 hr of of immobilization had increased the permeability of BBB mainly in younger rats. This increased permeability was significantly reduced with p-CPA, indomethacin or vinblastine pretreatment. Theophylline treatment caused early extravasation of Evans blue dye. The increased level of serotonin in immobilization and infusion of 5-HT in model experiments suggest a causative role of serotonin in the increased permeability of BBB induced by immobilization stress.

Effect of indomethacin (a prostaglandin synthetase inhibitor) on the permeability of blood-brain and blood-CSF barriers in rat.

Effect of indomethacin on the permeability of blood-brain and blood-csf barriers to Evans blue, bromophenol blue and horseradish peroxidase (HRP) was studied by administering the drug through right internal carotid artery, right external jugular vein and through intraperitoneal route in rats. Increased permeability was observed on internal carotid arterial injection but not following jugular vein or intraperitoneal injection. This increased permeability of blood-brain and blood-csf barriers following injection of indomethacin into the internal carotid artery is associated with a steep and sustained rise in mean arterial blood pressure (MABP), a feature not observed in bilateral adrenalectromised animals.