Thu Hien Le

To test the effect of increased AT 1 receptor expression on blood pressure, we used gene targeting to generate mouse lines with a tandem duplication of the AT 1A receptor gene locus ( Agtr1a ) along with >10 kb of 5′ flanking DNA. By successive breeding, we generated mice with 3 and 4 copies of the Agtr1a gene locus on an inbred 129/Sv background. AT 1A mRNA expression and AT 1 -specific binding of 125 I-angiotensin II were increased in proportion to Agtr1a gene copy number. These animals survived in expected numbers, and their body, heart, and kidney weights were similar to wild-type, 2-copy control mice. Pressor responses to angiotensin II were blunted in the 4-copy mice compared with control mice. In male mice, there was no correlation between resting blood pressure and Agtr1a gene copy number or AT 1A mRNA levels. However, in female mice, there was a highly significant positive correlation between blood pressure and AT 1A receptor expression, paralleled by significant increas...

Vascular injury and remodeling are common pathological sequelae of hypertension. Previous studies have suggested that the renin-angiotensin system acting through the type 1 angiotensin II (AT 1 ) receptor promotes vascular pathology in hypertension. To study the role of AT 1 receptors in this process, we generated mice with cell-specific deletion of AT 1 receptors in vascular smooth muscle cells using Cre/Loxp technology. We crossed the SM22 α- Cre transgenic mouse line expressing Cre recombinase in smooth muscle cells with a mouse line bearing a conditional allele of the Agtr1a gene ( Agtr1a flox ), encoding the major murine AT 1 receptor isoform (AT 1A ). In SM22 α- Cre + Agtr1a flox/flox (SMKO) mice, AT 1A receptors were efficiently deleted from vascular smooth muscle cells in larger vessels but not from resistance vessels such as preglomerular arterioles. Thus, vasoconstrictor responses to angiotensin II were preserved in SMKO mice. To induce hypertensive vascular remodeling, mi...

Glutathione S -transferase-μ1, GSTM1, belongs to a superfamily of glutathione S -transferases that metabolizes a broad range of reactive oxygen species and xenobiotics. Across species, genetic variants that result in decreased expression of the Gstm1 gene are associated with increased susceptibility for vascular diseases, including atherosclerosis in humans. We previously identified Gstm1 as a positional candidate in our gene mapping study for susceptibility to renal vascular injury characterized by medial hypertrophy and hyperplasia of the renal vessels. To determine the role of Gstm1 in vascular smooth muscle cells (VSMCs), we isolated VSMCs from mouse aortas. We demonstrate that VSMCs from the susceptible C57BL/6 mice have reduced expression of Gstm1 mRNA and its protein product compared with that of the resistant 129 mice. After serum stimulation, C57BL/6 VSMCs proliferate and migrate at a much faster rate than 129 VSMCs. Furthermore, C57BL/6 VSMCs have higher levels of reactive...

Background— Collectrin, a homologue of angiotensin converting enzyme 2, is expressed in pancreatic β cells and renal proximal tubular and collecting duct cells under the control of hepatocyte nuclear factors-1α and -1β. Because collectrin interacts with the soluble N -ethylmaleiamide-sensitive factor attachment protein receptor (SNARE) complexes, we investigated whether collectrin is involved in sodium handling in hypertension by vesicle trafficking of apical membrane proteins. Methods and Results— Collectrin physically interacts with the SNARE complex: snapin, synaptosomal-associated protein 23 kDa, syntaxin-4, and vesicle-associated membrane protein-2 in mIMCD-3 cells. siRNA knockdown of collectrin resulted in a reduction in membrane-associated aquaporin-2, α-epithelial Na + channel, and H + -ATPase. Collectrin and SNARE proteins were abundantly expressed in collecting ducts of Wistar-Kyoto rats. Wistar-Kyoto rats and spontaneously hypertensive rats 7 weeks of age were subjected t...

Defects in renal proximal tubule transport manifest in a number of human diseases. Although variable in clinical presentation, disorders such as Hartnup disease, Dent's disease, and Fanconi syndrome are characterized by wasting of solutes commonly recovered by the proximal tubule. One common feature of these disorders is aminoaciduria. There are distinct classes of amino acid transporters located in the apical and basal membranes of the proximal tubules that reabsorb >95% of filtered amino acids, yet few details are known about their regulation. We present our physiological characterization of a mouse line with targeted deletion of the gene collectrin that is highly expressed in the kidney. Collectrin-deficient mice display a reduced urinary concentrating capacity due to enhanced solute clearance resulting from profound aminoaciduria. The aminoaciduria is generalized, characterized by loss of nearly every amino acid, and results in marked crystalluria. Furthermore, in the kid...

AT1 double receptor (AT1A and AT1B) knockout mice have lower blood pressure, impaired growth, and develop early renal microvascular disease and tubulointerstitial injury. We hypothesized that there would be an increased expression of vasoactive, profibrotic, and inflammatory mediators expressed in the kidneys of AT1 double-knockout mice. We examined the renal expression of various mediator systems in control ( n = 6) vs. double-knockout mice ( n = 6) at 3–5 mo of age by real-time PCR, immunohistochemistry, and Western blot analysis. AT1 double-knockout mice show activation of Th1-dependent pathways (with increased expression of IFN-α, IL-2 mRNA) with increased expression of both monocyte (MCP-1 mRNA) and T cell (RANTES mRNA) chemokines, infiltration of CD4+ and CD11b+ cells, increased fibrosis-associated mediators (CTGF, TGF-β and TNF-α mRNA) and extracellular matrix (collagens I and III mRNA and protein) deposition compared with controls ( P < 0.05 for all markers). These change...

Hand-raising gesture is one of the most popular signs of communication, whose frequency is related to the classroom’s atmosphere, the attractiveness of the subject, and the level of interactions between students and teachers. However, automatic hand-raising gesture detection and recognition remains still a challenging problem mainly due to low hand resolution, hand occlusion, various backgrounds, and viewpoint changes. While majority of the existing methods focus on static hand-raising posture detection, in this paper, we propose a framework for dynamic hand gesture recognition from classroom videos consisting of two main stages: hand posture detection and dynamic hand gesture recognition. In hand posture detection stage, we extend the previous work by adding relative position-aware in non-local network. After detecting the hand-raising posture on static pixels, which in turn accelerates the performance images, at the dynamic hand gesture recognition stage, we incorporate object det...