Expression of the genes that mediate the first steps in steroidogenesis, the steroidogenic acute regulatory protein (STARD1), the cholesterol side-chain cleavage enzyme, cytochrome P450scc (CYP11A1) and 3beta-hydroxysteroid dehydrogenase/Delta5-Delta4 isomerase (HSD3B), is tightly controlled by a battery of transcription factors in the adrenal cortex, the gonads and the placenta. These genes generally respond to the same hormones that stimulate steroid production through common pathways such as cAMP signaling and common actions on their promoters by proteins such as NR5A and GATA family members. However, there are distinct temporal, tissue and species-specific differences in expression between the genes that are defined by combinatorial regulation and unique promoter elements. This review will provide an overview of the hormonal and transcriptional regulation of the STARD1, CYP11A1 and specific steroidogenic HSD3B genes in the adrenal, testis, ovary and placenta and discuss the current knowledge regarding the key transcriptional factors involved.
We describe how the histology course we teach to first-year medical students changed successfully from using glass slides and microscopes to using virtual slides and virtual microscopes. In 1988, we taught a classic medical histology course. Subsequently, students were loaned static labeled images on projection slides to introduce them to their microscope glass slides, and we made laser disks of histological images available in the teaching lab. In 2000, we placed the static labeled images and laboratory manual on the Web. We abandoned the Web-based approach in 2001. Faculty selected specific areas on microscope glass slides in student collections for scanning at a total magnification of 40, 100, 200, or 400. Christopher M. Prince of Petro Image, LLC, scanned the glass slides; digitized, encoded, and compressed (95%) the images; and placed them on CD-ROMs. The scanned images were viewed up to a magnification of 400 using the MrSID viewer (LizardTech software) and the computer as a virtual microscope. This viewer has many useful features, including effective microscope and telescope functions that provide greater versatility for sample study and speed in localizing structures than was possible with the actual microscope. Image detail is indistinguishable from that viewed under the light microscope at equivalent magnifications. Static labeled images were also placed on CD-ROMs to introduce students to the virtual slides. AN OVERVIEW OF TEACHING MEDICAL HISTOLOGY IN THE 20TH CENTURYMedical histology has been a longstanding basic science course in the medical school curriculum worldwide. Changes in histology course materials during the 20th century have reflected improvements in histological techniques and slide preparation as well as developments in light microscopes and associated photomicroscopy. Transmission and scanning electron photomicrographs were used in teaching histology during the second half of the 20th century. Changes in course content during the 20th century initially emphasized new knowledge of structure as observed at the light and electron microscope levels. Faculty members subsequently incorporated more histophysiology and histopathology into their courses to emphasize newly acquired information on the function and clinical relevance of the cells and tissues being studied. The presentation of a significant amount of cell biology also has been incorporated into textbooks and courses. Changes that were incorporated during the 1980s and 1990s have occurred at the same time as an emergence of pressures from the Liaison Committee on Medical Education (LCME) and local university administrators to decompress the curriculum and reduce student-faculty contact hours in courses, including histology. At a significant number of medical schools, financial constraints have resulted recently in only partial replacement of retiring faculty, and the teaching loads of remaining faculty, therefore, have increased.During the latter part of the 20th century and the beginning of the 21st century, there has been a rapi...
Scope-Diabetic embryopathy, a consequence of diabetic pregnancy is associated with increase in embryonic oxidative stress and apoptosis which lead to severe embryonic damage at early stage of organogenesis.Methods and results-This study investigated if resveratrol, found in red grapes and blueberries, may prevent diabetes-induced oxidative stress and apoptosis in embryos and have beneficial effects in diabetic dams. A rodent model of diabetic embryopathy was used. Diabetes was associated with lowered reduced glutathione levels (26.98%), increased total thiol (100.47%) and lipid peroxidation (124.73%) in embryos, and increased blood sugar (384.03%), cholesterol (98.39%) and triglyceride (1025.35%) in diabetic dams. Increased apoptosis (272.20%) was also observed in the embryos of diabetic dams. Administration of resveratrol (100 mg/kg b. wt.) during pregnancy prevented both oxidative stress and apoptosis in embryos. Resveratrol reduced embryonic maldevelopment by improving embryo weight (41.23%), crown rump length (16.50%) and somite number (11.22%). It further improved the glucose (33.32%) and lipid (cholesterol 41.74%, triglyceride 60.64%) profile of the diabetic dams which also represents the protective role of resveratrol in diabetes.Conclusion-Resveratrol was found to prevent embryonic oxidative stress and apoptosis. It also improved glucose and lipid profile of diabetic dams indicating the beneficial effects in diabetic pregnancy.
GATA transcription factors are emerging as critical players in mammalian reproductive development and function. GATA-4 contributes to fetal male gonadal development by regulating genes mediating Müllerian duct regression and the onset of testosterone production. GATA-2 expression appears to be sexually dimorphic being transiently expressed in the germ cell lineage of the fetal ovary but not the fetal testis. In the reproductive system, GATA-1 is exclusively expressed in Sertoli cells at specific seminiferous tubule stages. In addition, GATA-4 and GATA-6 are localized primary to ovarian and testicular somatic cells. The majority of cell transfection studies demonstrate that GATA-1 and GATA-4 can stimulate inhibin subunit gene promoter constructs. Other studies provide strong evidence that GATA-4 and GATA-6 can activate genes mediating gonadal cell steroidogenesis. GATA-2 and GATA-3 are found in pituitary and placental cells and can regulate alpha-glycoprotein subunit gene expression. Gonadal expression and activation of GATAs appear to be regulated in part by gonadotropin signaling via the cyclic AMP-protein kinase A pathway. This review will cover the current knowledge regarding GATA expression and function at all levels of the reproductive axis.
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