Molecular mechanisms of glucocorticoid resistance/hypersensitivity. Potential clinical implications.
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Acquired Immunodeficiency Syndrome↗
Biomedical subjects
S Elliot
Publications and source records attributed to S Elliot.
Urinary excretion of aquaporin-2 in humans: a potential marker of collecting duct responsiveness to vasopressin.
The vasopressin-sensitive water channel (aquaporin 2; AQP-2) mediates water transport across the apical plasma membrane of the renal collecting ducts and is excreted in human urine. This study presents the hypothesis that measurements of the AQP-2 excretion rate might be used as a marker of collecting-duct responsiveness to vasopressin, and therefore could be useful in the clinical evaluation of various water-balance disorders. This study presents information about the development of an antibody to human AQP-2, and measures the urinary excretion of AQP-2 by quantitative Western analysis. A standard curve of band densities was generated by using known quantities of the modified immunizing peptide to derive the amount of AQP-2 contained in aliquots of urine. AQP-2 urinary excretion changed with short-term alterations in hydration status produced either by water loading (76% decrease, P < 0.01) or by 3% sodium chloride (760% increase, P < 0.01). Steady-state 24-h urinary excretion of AQP-2 was 43 +/- 10 nmol/24 h (or 28.5 +/- 6.9 pmol/mg creatinine), and 20 +/- 6 nmol/24 h (or 18.3 +/- 7.9 pmol/mg creatinine) in men and women, respectively. Therefore, urinary AQP-2 excretion can be quantified by using Western analysis, and may serve as a marker of collecting-duct responsiveness to vasopressin in different physiologic settings.
Adult↗
The non-ligand binding beta-isoform of the human glucocorticoid receptor (hGR beta): tissue levels, mechanism of action, and potential physiologic role.
BACKGROUND: Alternative splicing of the transcripts of the human glucocorticoid receptor gene results in two mutually exclusive products, the classic, ligand-binding glucocorticoid receptor (hGR alpha), and a dominant negative non-ligand-binding isoform, hGR beta. MATERIALS AND METHODS: We examined the existence of and quantified both hGR alpha and hGR beta isoforms in a panel of human tissues, as well as in intact and fractionated HeLa cells, using specific quantitative Western blots and/or immunocytochemistry. We studied the potential interactions of hGR beta with heat shock protein (hsp) 90 and/or hGR alpha using cross-immunoadsorption/precipitation procedures followed by Western blots. RESULTS: For the first time, we demonstrated the natural existence of the hGR beta protein, which was widely expressed in human tissues. The ratio of immunoreactive hGR alpha to hGR beta varied from 0.2 to 1.0 among different tissues, and was approximately 0.2 in HeLa cells. In the latter, both isoforms were distributed in the cytoplasm and nucleus in the absence of the hormonal ligand, and translocated into the nucleus after addition of dexamethasone. The cytosolic and nuclear hGR alpha-to-hGR beta ratio remained the same before and after dexamethasone exposure, suggesting that upon activation the two isoforms translocated into the nucleus in equal proportions. hGR alpha- and hGR beta-specific antibodies cross-adsorbed and precipitated cytosolic and nuclear glucocorticoid hGR alpha and hGR beta, respectively, as well as hsp90, suggesting that hGR alpha and hGR beta are in complex with hsp90 and/or each other. CONCLUSIONS: The hGR beta protein is widely expressed throughout the human body and present mostly in the cytoplasm of human cells, in complex with hsp90 and other proteins. In the presence of glucocorticoid, hGR beta probably heterodimerizes with ligand-bound hGR alpha and translocates into the nucleus to act as a dominant negative inhibitor of the classic receptor.
Alternative Splicing↗
Overexpression of transforming growth factor-beta 1 mRNA is associated with up-regulation of glomerular tenascin and laminin gene expression in nonobese diabetic mice.
Nonobese diabetic (NOD) mice spontaneously develop immune-mediated insulin-dependent diabetes mellitus and nephropathy, providing an opportunity to study the early molecular events in a model of diabetic glomerulosclerosis. The expression of several genes coding for growth factors and extracellular matrix was examined in microdissected glomeruli, by the use of reverse transcription-competitive polymerase chain reaction, in diabetic NOD mice (mean duration of diabetes, 28.5 +/- 7 days) and age-matched nondiabetic NOD mice with normal glucose tolerance. The levels of mRNA coding for transforming growth factor-beta 1, tenascin, and laminin B1 increased 1.9-, 2.0-, and 1.7-fold, respectively, whereas platelet-derived growth factor (PDGF)-B, alpha 1(IV) collagen, 72-kd collagenase, alpha-smooth muscle actin, and beta-actin mRNA remained stable in the diabetic mice. The kidney advanced glycosylation end-products levels increased 2.1-fold in the diabetic mice, and the diabetic glomeruli showed an accumulation of tenascin and laminin but not of type IV collagen by immunofluorescence microscopy. There was no increase in cell number per glomerulus after the onset of diabetes, a finding consistent with stable PDGF-B and alpha-smooth muscle actin mRNA levels. These findings provide evidence that increased glomerular transforming growth factor-beta 1, but not PDGF-B, mRNA is associated with the up-regulation of tenascin and laminin expression after advanced glycosylation endproduct accumulation, early after the onset of diabetes.
Animals↗
Glomerulosclerosis and body growth are mediated by different portions of bovine growth hormone. Studies in transgenic mice.
BACKGROUND: Mice transgenic for bovine growth hormone (bGH) gene have increased body weight and severe glomerulosclerosis leading to death in uremia. EXPERIMENTAL DESIGN: The aim of this study was to determine if body growth and glomerulosclerosis were mediated by different bGH regions. Amino acid substitutions in the bGH alpha-helix III were generated, and lines of transgenic mice that expressed these products were developed. Female transgenic mice carrying the native bGH gene (bGH mice), a mutated bGH gene that encodes a destabilized alpha-helix III (bGH-L121P, E126G; bGH-m11 mice), or a mutated bGH gene that encodes a perfect amphiphilic alpha-helix III (bGH-E117L, G119R, A122D; bGH-m8 mice) were examined at 2-3 months and 6-9 months of age. Body, kidney, and heart weights were measured. Urinary glucose, albumin, creatinine, and serum glucose were measured in all mice. Serum levels of insulin-like growth factor I (IGF-I) were measured in the 2-3 month group. Whole blood hemoglobin A1 was measured in some mice of the 6-9 month group. Kidney sections were examined by light and immunofluorescence microscopy. Glomerular volume was measured and related to body weight by allometry. RESULTS: The bGH-m11 mice developed glomerulosclerosis indistinguishable from that seen in bGH transgenic mice, even though they had normal body size. Glomerular growth exceeded body growth by allometry in both bGH and bGH-m11 strains. bGH-m8 mice had glomeruli of appropriate size and normal histologic appearance; however, they were dwarfs. IGF-I was increased in bGH mice; they also had an increased albumin/creatinine ratio at 6-9 months. None of the mice were hyperglycemic. CONCLUSIONS: These data indicated that development of glomerulosclerosis and body growth promotion were mediated by different regions of the growth hormone molecule. The glomerular response to bGH was unique and consisted of increased size and glomerulosclerosis.
Animals↗
The combined use of vibrostimulation and in vitro fertilization: successful pregnancy outcome from a retrograde specimen obtained from a spinal cord-injured male.
While pregnancies have been documented through the independent use of the vibrator method, from other methods of procuring ejaculate from spinal cord injured men, and from artificial insemination using a retrograde specimen, we believe that this is the first case report of a live birth resulting from a retrograde ejaculate obtained by vibration from a spinal cord-injured male whose partner underwent in vitro fertilization. Vibrostimulation may well be successful in the two-thirds of men whose spinal cord lesions are at the T10 neurological level and above, who have an intact bulbocavernosus reflex and anal tone but no pain or temperature sensation of the genitalia. Blood pressure monitoring, prevention of autonomic dysreflexia, alkalinization, dilution and infection control of urine, and retrograde specimen retrieval are all important techniques to ensure patient safety and optimal ejaculates. The timing of ovulation and insemination is the crucial factor for the partner of a SCI male whose sperm quality is poor. A complete gynecological workup, including studies of tubal patency, should be done before embarking on a series of artificial inseminations. Stimulation of ovulation and well-timed inseminations should optimize the chance of conception. Depending on semen analysis, female partner factors, and emotional and financial costs, IVF can appropriately be either an early or a final option.
Adult↗
Hepatoma G2 conditioned medium facilitates early outgrowth of endothelial cells from isolated glomeruli.
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Carcinoma, Hepatocellular↗
Limb volume measurements in peripheral arterial disease.
A simple method for measuring limb volumes of patients with peripheral arterial disease undergoing limb blood flow measurement is described. The device uses the change in surface level of water in a cylindrical reservoir to generate a voltage which is amplified and converted to a volume. The plethysmograph is stable and accurate over a wide range of limb volumes. For patients with leg ulcers or gangrene, where water immersion is not possible, a geometrical model has been developed which allows the volume to be calculated from a series of six external measurements. Comparison with measured volumes in 46 patients has shown this model to be accurate with a mean error of 3.3%. It provides a convenient alternative to direct measurement in these patients.
Blood Volume↗
The contribution of glomerular mesangial cells to progressive glomerulosclerosis.
These data from in vitro studies, partially confirmed on intact glomeruli, suggest that glomerular cells are not only responsive to a number of growth-regulatory peptides but they are also important sources of several of these agents. The studies on transgenic mice confirm the potential role of the insulin-like peptides. This model also provides clear evidence that genetically directed modifications of cell behavior are important in the pathogenesis of glomerulosclerosis. The ability of glomerular cells to undergo proliferation and participate in hypertrophy of the glomerulus may be a critical determinant in the development of progressive glomerulosclerosis. That this ability is controlled by genetic differences between species and individuals seems well-established in both animal studies and clinical experience.
Animals↗
Glomerular epithelial, mesangial, and endothelial cell lines from transgenic mice.
The culture of glomerular cells has represented an important tool in the understanding of individual glomerular cell functions. However, the complexity of the glomerulus has made it difficult to obtain pure cell populations. It has also been difficult to culture glomerular endothelial cells, even as mixed cell populations. At present there are no established glomerular cell lines from any source. We have established permanent cell lines of cloned glomerular epithelial, mesangial, and endothelial cells from a line of mice transgenic for the early region of simian virus 40 (SV40). These mice appear normal at birth but by three to four months of age have sclerosis affecting a variable percentage of their glomeruli. The cells maintain features characteristic of their normal counterparts despite their transformed phenotype. These cell lines could be useful tools in understanding the pathogenesis of glomerulosclerosis in this transgenic mouse model and in studying those features of normal glomerular cell biology which are not altered by a transformed phenotype.
Animals↗
Zinc tolerance tests in chronic uremia.
The intestinal absorption of zinc was investigated in 12 control subjects and in 20 patients or maintenance hemodialysis by means of a zinc tolerance test during fasting. Ten patients (Group I) were on long-term vitamin D therapy and 10 (Group II) were not receiving vitamin D. After baseline plasma zinc measurements, a single dose of 50 mg zinc was ingested and plasma zinc levels were measured at hourly intervals for 4 hours thereafter. Peak plasma zinc levels were significantly lower in Group II patients than in controls or patients in Group I suggesting impaired absorption. No significant difference was found between controls and Group I patients. Two patients had normal zinc tolerance tests while on vitamin D therapy, but abnormal tests while off vitamin D. We conclude that the intestinal absorption of zinc may be impaired in chronic uremia, probably secondary to abnormal metabolism of vitamin D.
Adult↗
Effect of 7 8-benzoflavone on the duration of zoxazolamine paralysis and hexobarbital hypnosis in rats.
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Animals↗