Detection of a physiological juvenile phase and the central role of pericytes in human dermal microvascular aging.
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Adolescent↗
Biomedical subjects
Ramesh C Nayak
Publications and source records attributed to Ramesh C Nayak.
Albuminuria and hypertension are independently associated with circulating antipericyte autoantibodies in type 2 diabetic patients.
AIMS: To determine whether albuminuria, hypertension, or HbA 1c are independently associated with antipericyte autoantibodies (APAAs) in type 2 diabetes mellitus. METHODS: Two hundred ninety-nine subjects with different degrees of retinopathy according to the Early Treatment Diabetic Retinopathy Study Scale participated in this study. Albuminuria was defined as an albumin/creatinine ratio above the normal cutoff limit, that is, 2.0 g/mol for men and 2.8 g/mol for women. Hypertension was defined as a diastolic blood pressure more than 90 mm Hg, a systolic blood pressure more than 140 mm Hg, or pharmacological antihypertensive treatment. Serum APAAs were detected by immunofluorescence on tissue-cultured bovine retinal pericytes. Association analysis was performed using univariate and multivariate statistical tools. RESULTS: In type 2 diabetes, APAAs were independently associated with albuminuria (OR = 0.56; P < .04), hypertension (OR = 2.21; P < .01), as well as with proliferative retinopathy (OR = 0.39; P < .01). CONCLUSIONS: The increased prevalence of APAA in patients with hypertension may suggest that these antibodies are related to tissue damage and repair and that the decline in frequency with albuminuria may serve as a marker for more advanced angiopathy. Future longitudinal studies are needed to determine whether the frequency of APAA is associated with the progression of angiopathy, and to determine the biological activity and antigens recognized by the antibody.
Aged↗
A novel homologue of coronin colocalizes with actin in filament-like structures in Leishmania.
The presence of actin in Leishmania has recently been demonstrated, but the functional form of this protein (filamentous actin) has not yet been identified. We report here that the putative coronin homologue identified in the Leishmania genome is invariably associated with the filament-like structures of actin in Leishmania promastigotes. The occurrence of filamentous structures is significantly increased upon overexpression of Leishmania coronin as its GFP fusion product in Leishmania cells. However, expression of Leishmania actin or coronin alone in mammalian cells does not result in formation of any filament-like structures of Leishmania actin or association of Leishmania coronin with mammalian filamentous actin, but coexpression of both the proteins in these cells leads to formation of filamentous structures containing Leishmania actin and coronin. The high specificity of Leishmania coronin for Leishmania actin could be attributed to its unique structure as it differs from other coronins not only in the unique region but also in the actin-binding site and leucine zipper motif. These results taken together indicate that Leishmania contains a novel form of coronin which colocalizes with actin in filament-like structures in these cells.
Actin Cytoskeleton↗
Melanocytes express 3G5 surface antigen.
The 3G5-reactive ganglioside antigen (3G5 antigen) is expressed on the surface of various cell types including pericytes, pancreatic islet cells, thyroid follicular cells, and cells of the pituitary and the adrenal medulla. Expression on melanocytes has not yet been reported. We examined 148 5-microm cryosections of 12 normal skin samples and 45 skin tumors (21 melanocytic nevi, 8 malignant melanoma primaries, 4 metastases of malignant melanoma, 3 basal cell carcinomas, and 9 pigmented seborrheic keratoses) by triple fluorescence technique with the monoclonal antibody 3G5, DNA fluorochrome, and the anti-melanocytic antibody A103 (Anti-Melan-A). In normal skin, 3G5 reactivity was detected in epidermal melanocytes of 4 of 12 cases with 14.8 +/- 24.1% positive melanocytes; 20 of 21 nevi (72.2 +/- 29.1% positive nevus cells, mean +/- SD), 8 of 8 primary melanomas (83.9 +/- 12.3% positive melanoma cells), and 4 of 4 melanoma metastases (82.5 +/- 6.5% positive melanoma cells) expressed the 3G5 antigen. All tumor cells of investigated basal cell carcinoma or seborrheic keratosis were 3G5 negative. This is the first report of 3G5 antigen expression in melanocytes. The data demonstrate high expression of this ganglioside in the aggregated melanocytes of malignant or benign tumors but low or absent expression in singular melanocytes (normal epidermis, seborrheic keratoses) reflecting a different biologic state.
Animals↗
Monoclonal antibody (3G5)-defined ganglioside: cell surface marker of corneal keratocytes.
PURPOSE: To evaluate the anti-ganglioside monoclonal antibody 3G5 as a marker of corneal keratocytes. METHODS: 3G5 expression on keratocytes was investigated by immunofluorescence microscopy. Studies were performed on frozen sections of normal human, bovine, porcine, rabbit, rat, and mouse corneas and on repairing rabbit cornea. In vitro studies were performed on tissue-cultured human, bovine, porcine, mouse, and rabbit keratocytes. RESULTS: 3G5 stained frozen sections of human, bovine, porcine, rat, and rabbit cornea but not mouse cornea and the staining pattern followed the distribution of stromal keratocytes but did not stain epithelium or endothelium. Subconfluent human and bovine keratocyte cultures were 3G5 negative. Almost 100% of the human and bovine cells that were maintained at confluence without replacement of serum-containing culture medium for 2 weeks became 3G5 positive. The 3G5 antigen was constitutively expressed on cultured rabbit and porcine keratocytes under all conditions examined. Mouse keratocyte cultures did not express 3G5. The 3G5 antigen was not present on myofibroblastic cells in the repairing area of a full-thickness wound in rabbit cornea that had been healing for 20 days. The area surrounding the healing wound expressed 3G5 antigen in an altered distribution, whereas 3G5 antigen was distributed in the expected pattern in areas that were distant from the wound. When rabbit keratocytes were induced to express the myofibroblast marker alpha-smooth muscle actin by treatment with TGFbeta1 in vitro, the pattern of 3G5 staining was altered. CONCLUSIONS: The 3G5 antigen is a useful marker for the identification of corneal keratocytes and for documenting their response to environmental stimuli associated with wound repair.
Adult↗
Bovine retinal pericytes are resistant to glucose-induced oxidative stress in vitro.
Diabetic retinopathy is a sight-threatening complication of diabetes, and loss of pericytes represents early signs of its development. We tested the hypothesis that high glucose levels may induce signs of oxidative stress in cultured bovine retinal pericytes. Pericytes were exposed to either normal (5.5 mM) or high (22 mM) glucose levels for 1, 3, and 5 days. Signs of oxidative stress were measured by expression of copper/zinc superoxide dismutase, manganese superoxide dismutase, catalase, and glutathione peroxidase using real-time RTPCR. To elucidate the role of oxidative stress, we also measured glutathione (GSH) concentration in the cells and investigated the impact of thiol-reactive metal ions and hydrogen peroxide (H(2)O(2)) on intracellular GSH. Despite the stimulation with high glucose, thiol-reactive metal ions, or H(2)O(2), there was no clear increased expression of antioxidant enzymes or influence of GSH levels. Lipid peroxidation (malondialdehyde level) was increased in bovine aortic smooth muscle cells, but not in bovine retinal pericytes. The data indicate that pericytes do not develop oxidative stress in response to hyperglycemia. However, it is not definitively excluded that oxidative stress may occur after longer time periods of glucose stimulation.
Animals↗