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Biomedical subjects

K Thapar

Publications and source records attributed to K Thapar.

24 records · Page 2Linked to original sources
PubMed1995

Surgical management of pituitary adenomas.

Surgical management of pituitary adenomas continues to be a safe and effective method, suitable for a large number of patients suffering from the effects of these lesions. Frequently surgery is just part of an overall programme that includes medical management and radiation therapy as well. It is important for the physicians and the patients to understand that surgery alone may not be totally successful, but that with careful follow-up and appropriate adjunctive management, patients with pituitary tumours may live normal lives, and may enjoy reversal of the endocrine and visual problems that had been caused by their tumours. Careful study of surgically managed patients has contributed to some of the advances that have occurred in the overall management of pituitary adenomas and in our understanding of their biology, pathophysiology and pathogenesis.

Adenoma↗
PubMed1994

Effects of spaceflight on morphology of the rat adenohypophysis.

To determine the effects of spaceflight on the anterior pituitary gland, the adenohypophyses of rats after a 7-day spaceflight aboard the space shuttle Endeavor (STS-54) were investigated by histology, immunohistochemistry, morphometry, electron microscopy, and in situ hybridization and were compared with synchronous control rats. Morphometry revealed the corticotrophs of space-flown rats to be significantly enlarged, demonstrating 46-48% increases in mean cell, nuclear, and cytoplasmic areas. These corticotrophs also exhibited striking ultrastructural signs of heightened secretory activity. Furthermore, their expression of proopiomelanocortin mRNA, the transcript encoding the precursor protein from which adrenocorticotropic hormone is posttranslationally cleaved, was also significantly enhanced, a finding consistent with their hypersecretory state. Gonadotrophs also exhibited significant increments in mean nuclear, cell, and cytoplasmic areas of 22, 45, and 51%, respectively; however, they were not accompanied by ultrastructural evidence of increased secretory function. There were no morphological changes in somatotrophs, lactotrophs, or thyrotrophs, nor were there any significant changes in the overall frequency of any one adenohypophyseal cell type in comparison with control. The structural integrity of all adenohypophyseal secretory and vascular elements was preserved after spaceflight, as there was neither evidence of necrosis nor other forms of cellular injury in spaceflown specimens. Capillaries were patent, and neither endothelial damage nor thrombosis was noted. These data suggest that spaceflight is accompanied by a selective morphological response in the anterior pituitary, one characterized by hypertrophy of both corticotrophs and gonadotrophs and by enhanced endocrine activity of the former.

Adrenocorticotropic Hormone↗
PubMed1994

Estrogen receptor gene expression in craniopharyngiomas: an in situ hybridization study.

Craniopharyngiomas are histologically benign epithelial neoplasms of the sellar region that frequently exhibit invasive and aggressive local growth. In this study, we have investigated the presence and cellular distribution of estrogen receptor messenger ribonucleic acid by in situ hybridization in 23 surgically removed craniopharyngiomas. All craniopharyngiomas studied, including 19 adamantinomatous and 4 papillary variants, uniformly expressed the estrogen receptor gene. In all cases, an intense estrogen receptor messenger ribonucleic acid hybridization signal was demonstrated; one localized exclusively to the epithelial cells of the tumor. Connective tissue and vascular elements were devoid of hybridization signal. Coexpression of the estrogen receptor protein was also studied by immunohistochemistry. Despite the relative abundance of estrogen receptor message in all cases studied, the estrogen receptor protein was focally but conclusively detected in only two tumors. The basis of this discrepancy is unclear. Progesterone receptor protein was also studied in all cases; however, its definitive presence was noted in only one instance and, in that case, in only occasional nuclei. The expression of the estrogen receptor gene by the proliferative epithelial elements of craniopharyngiomas raises the questions of a possible hormonal component to the genesis and/or progression of the craniopharyngiomas and a potential responsiveness to therapeutic hormonal manipulation.

Cell Division↗
PubMed1992

Correlation of plasma color index with serum bilirubin in neonatal hyperbilirubinemia.

In this study, a simple method was evaluated for serum bilirubin estimation in neonates. The color of plasma was compared with various dilutions of potassium dichromate. Readings were then compared with serum bilirubin levels obtained by diazo reaction. The coefficient of correlation (r = 0.7947) between the two was statistically significant. It is concluded that the color index provides reliable estimates of serum bilirubin levels.

Bilirubin↗
PubMedDate not supplied

Brain tumors.

Brain tumors are a relatively common cancer in all age groups, and the incidence of both primary and metastatic brain tumors is increasing. Fortunately, dramatic advances in methods of diagnosis, surgical technique, and adjuvant therapy have all contributed to an improved outlook for patients with brain tumors. This article reviews the classification, symptoms, diagnosis, and treatment of brain tumors.

Adult↗