26
|
Rasul R, Cole N, Balasubramanian D, Chen R, Kumar N, Willcox MDP. Interaction of the antimicrobial peptide melimine with bacterial membranes. Int J Antimicrob Agents 2010; 35:566-72. [PMID: 20227248 DOI: 10.1016/j.ijantimicag.2010.02.005] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/02/2009] [Revised: 02/02/2010] [Accepted: 02/04/2010] [Indexed: 11/26/2022]
Abstract
Melimine is a novel cationic peptide possessing broad-spectrum antimicrobial activity that is retained when attached to a surface, suggesting that interactions with bacterial membranes may be of primary importance to its activity. The effects of alterations in the environment on the conformation of melimine were investigated using circular dichroism and fluorescence spectra in membrane-mimetic solvents. Furthermore, the interactions of melimine with bacterial membranes of Pseudomonas aeruginosa and Staphylococcus aureus were examined using scanning electron and fluorescence microscopy, and perturbation of membrane integrity was tested by measurement of melimine-mediated diSC(3)-5 dye release from bacterial cells. Melimine has a predominantly random coil conformation that adopts a helical fold when exposed to organic solvents. However, when it is solubilised in micelles of sodium dodecyl sulphate, which are bacterial membrane-mimetic, the alpha-helical content increases to ca. 35-40%. A major effect of melimine was on the integrity of the cytoplasmic membrane both for P. aeruginosa and S. aureus. However, for P. aeruginosa the rapid loss of cytoplasmic membrane integrity correlated directly with loss of cell viability, whilst for S. aureus maximal dye release was obtained at concentrations where there was no significant loss of viability. There have been few studies to date investigating differences in the action of cationic peptides towards Gram-positive and Gram-negative bacteria. Consequently, further investigation of these mechanistic differences may allow more refined targeting of increasingly difficult-to-treat bacterial infections and/or further inform design of novel peptides with improved broad-spectrum activity.
Collapse
|
27
|
Gopal M, Balasubramanian D, Kanagarajah P, Anirudhan A, Murugan P. Madras Medical College: 175 years of medical heritage. THE NATIONAL MEDICAL JOURNAL OF INDIA 2010; 23:117-120. [PMID: 20925216] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 05/30/2023]
|
28
|
Marappan K, Deiveegan K, Balasubramanian D, Sundaram A. Fungal cerebellar tonsillar abscess as a cause of quadriparesis. Neurol India 2009; 55:311-2. [PMID: 17921667 DOI: 10.4103/0028-3886.35699] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/04/2022]
|
29
|
Metlapally S, Costello MJ, Gilliland KO, Ramamurthy B, Krishna PV, Balasubramanian D, Johnsen S. Analysis of nuclear fiber cell cytoplasmic texture in advanced cataractous lenses from Indian subjects using Debye-Bueche theory. Exp Eye Res 2007; 86:434-44. [PMID: 18191834 DOI: 10.1016/j.exer.2007.11.018] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/22/2007] [Revised: 11/20/2007] [Accepted: 11/28/2007] [Indexed: 12/13/2022]
Abstract
Alterations in ultrastructural features of the lens fiber cells lead to scattering and opacity typical of cataracts. The organelle-free cytoplasm of the lens nuclear fiber cell is one such component that contains vital information about the packing and organization of crystallins critical to lens transparency. The current work has extended analysis of the cytoplasmic texture to transparent and advanced cataractous lenses from India and related the extent of texturing to the nuclear scattering observed using the Debye-Bueche theory for inhomogeneous materials. Advanced age-related nuclear cataracts (age-range 38-75 years) and transparent lenses (age-range 48-78 years) were obtained following extracapsular cataract removal or from the eye bank, at the L.V. Prasad Eye Institute. Lens nuclei were Vibratome-sectioned, fixed and prepared for transmission electron microscopy using established techniques. Electron micrographs of the unstained thin sections of the cytoplasm were acquired at 6500x and percent scattering for wavelengths 400-700 nm was calculated using the Debye-Bueche theory. Electron micrographs from comparable areas in an oxidative-damage sensitive (OXYS) rat model and normal rat lenses preserved from an earlier study were used, as they have extremely textured and smooth cytoplasms, respectively. The Debye-Bueche theoretical approach produces plots that vary smoothly with wavelength and are sensitive to spatial fluctuations in density. The central lens fiber cells from advanced cataractous lenses from India and the OXYS rat, representing opaque lens nuclei, produced the greatest texture and scattering. The transparent human lenses from India had a smoother texture and less predicted scattering, similar to early cataracts from previous studies. The normal rat lens had a homogeneous cytoplasm and little scattering. The data indicate that this method allowed easy comparison of small variations in cytoplasmic texture and robustly detected differences between transparent and advanced cataractous human lenses. This may relate directly to the proportion of opacification contributed by the packing of crystallins. The percent scattering calculated using this method may thus be used to generate a range of curves with which to compare and quantify the relative contribution of the packing of crystallins to the loss of transparency and scattering observed.
Collapse
|
30
|
Balasubramanian D. Photodynamics of Cataract: An Update on Endogenous Chromophores and Antioxidants¶. Photochem Photobiol 2007. [DOI: 10.1111/j.1751-1097.2005.tb00215.x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
|
31
|
Fatima A, Sangwan VS, Iftekhar G, Reddy P, Matalia H, Balasubramanian D, Vemuganti GK. Technique of cultivating limbal derived corneal epithelium on human amniotic membrane for clinical transplantation. J Postgrad Med 2006; 52:257-61. [PMID: 17102542] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/12/2023] Open
Abstract
BACKGROUND The technique of transplantation of cultivated limbal epithelium rather than direct limbal tissue isa novel method of "cell therapy" involved in reconstructing the ocular surface in severe limbal stem cell deficiency [LSCD], caused by chemical burns. AIM To describe a simple feeder-cell free technique of cultivating limbal epithelium on human amniotic membrane[HAM]. MATERIALS AND METHODS The limbal tissues (2 mm) were harvested from patients with LSCD. These tissues were proliferated in vitro on HAM supplemented by human corneal epithelial cell medium and autologous serum. Cultures covering more > or = 50% area of 2.5 x 5 cm HAM were considered adequate for clinical use. The cultured epithelium was characterized by histopathology and immunophenotyping. RESULTS A total of 542 cultures out of 250 limbal tissues were cultivated in the laboratory from January 2001 through July 2005. The culture explants showed that clusters of cells emerging from the edge of the explants in one-three days formed a complete monolayer within 10-14 days. In 86% of cultures (464 of 542), the growth was observed within one-two days. Successful explant cultures were observed in 98.5% (534 of 542 cultures) with 91% explant cultures showing an area of > or = 6.25 cm2 (6.25 - 12.5 cm2 range). The cultivated epithelium was terminated between 10-14 days for clinical transplantation. The problems encountered were inadequate growth (2 of 542) and contamination (2 of 542). CONCLUSIONS We demonstrate a simple technique of generating a sheet of corneal epithelium from a limbal biopsy. This new technique could pave the way for a novel form of cell therapy.
Collapse
|
32
|
Balasubramanian D, Kaufman PL. Research opportunities in vision: a report of the U.S.-Indo workshops on collaborative research. Invest Ophthalmol Vis Sci 2006; 47:1717-35. [PMID: 16638973 DOI: 10.1167/iovs.06-0071] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
|
33
|
Sultana A, Sridhar MS, Klintworth GK, Balasubramanian D, Kannabiran C. Allelic heterogeneity of the carbohydrate sulfotransferase-6 gene in patients with macular corneal dystrophy. Clin Genet 2005; 68:454-60. [PMID: 16207214 DOI: 10.1111/j.1399-0004.2005.00517.x] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Allelic heterogeneity of the carbohydrate sulfotransferase-6 gene in patients with macular corneal dystrophy. Macular corneal dystrophy (MCD) is an autosomal recessive disorder characterized by grayish white opacities in the cornea. It is caused by mutations in the carbohydrate sulfotransferase-6 (CHST6) gene, which codes for the enzyme corneal N-acetylglucosamine-6-sulfotransferase. This enzyme catalyzes the sulfation of keratan sulfate, an important component of corneal proteoglycans. We screened 31 patients from 26 families with MCD for mutations in the coding region of the CHST6 gene. Twenty-six different mutations were identified, of which 14 mutations are novel. The novel mutations are one nonsense mutation found in one patient (Trp2Ter), one frameshift (insertion plus deletion) mutation in two patients (His335fs), and 12 missense mutations (Leu3Met, Ser54Phe, Val56Arg, Ala73Thr, Ser98Leu, Cys165Trp, Ser167Phe, Phe178Cys, Leu193Pro, Pro204Arg, Arg272Ser, and Arg334Cys) in 11 patients. These data demonstrate a high degree of allelic heterogeneity of the CHST6 gene in patient populations with MCD from Southern India, where this disease may have a relatively higher prevalence than in outbred communities.
Collapse
|
34
|
Balasubramanian D. Photodynamics of cataract: an update on endogenous chromophores and antioxidants. Photochem Photobiol 2005; 81:498-501. [PMID: 15623354 DOI: 10.1562/2004-11-01-ra-354] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
Cataract of the eye lens is characterized by (1) progressive opacification or loss of transparency; (2) accumulation of molecules that absorb in the UV-visible range of the spectrum; and (3) formation of fluid-filled vacuoles, particularly in diabetics when sugar levels in the lens are high. Of the various causative factors for cataract, light is an important one. Because the level of light below 320 nm reaching the lens is quite low, photodynamic effects of endogenous compounds absorbing in the UV-A-visible region become important in this connection. In this update we summarize a list of accumulant chromophores that have been identified in aging and cataract human lenses and their roles as potential sensitizers, antioxidants or as benign filters. Because such photodynamic cataractogenesis is oxidative in nature, we also cite examples where administration of antioxidants could help delay cataract progression.
Collapse
|
35
|
Kaur K, Reddy ABM, Mukhopadhyay A, Mandal AK, Hasnain SE, Ray K, Thomas R, Balasubramanian D, Chakrabarti S. Myocilin gene implicated in primary congenital glaucoma. Clin Genet 2005; 67:335-40. [PMID: 15733270 DOI: 10.1111/j.1399-0004.2005.00411.x] [Citation(s) in RCA: 68] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/01/2022]
Abstract
Primary congenital glaucoma (PCG) has been associated with CYP1B1 gene (2p21), with a predominantly autosomal recessive mode of inheritance. Our earlier studies attributed CYP1B1 mutations to only 40% of Indian PCG cases. In this study, we included 72 such PCG cases where CYP1B1 mutations were detected in only 12 patients in heterozygous condition, implying involvement of other gene(s). On screening these patients for mutations in myocilin (MYOC), another glaucoma-associated gene, using denaturing high-performance liquid chromatography followed by sequencing, we identified a patient who was double heterozygous at CYP1B1 (c.1103G>A; Arg368His) and MYOC (c.144G>T; Gln48His) loci, suggesting a digenic mode of inheritance of PCG. In addition, we identified the same MYOC mutation, implicated for primary open angle glaucoma, in three additional PCG patients who did not harbor any mutation in CYP1B1. These observations suggest a possible role of MYOC in PCG, which might be mediated via digenic interaction with CYP1B1 and/or an yet unidentified locus associated with the disease.
Collapse
|
36
|
Balasubramanian D. Photodynamics of Cataract: An Update on Endogenous Chromophores and Antioxidants¶. Photochem Photobiol 2005. [DOI: 10.1562/2004-11-01-ra-354.1] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
|
37
|
Balasubramanian D, Ramesh VG, Deiveegan K, Ghosh M, Mallikarjuna VS, Annapoorneswari TP, Chidambaranathan N, Ramani KVN. Desmoplastic infantile ganglioglioma -- a case report. Neurol India 2004; 52:384-6. [PMID: 15472436] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/30/2023]
Abstract
Desmoplastic infantile ganglioglioma is a very rare supratentorial tumor occurring in the first two years of life. A five-month-old female infant presented with recurrent seizures, large head and loss of acquired milestones. Computerized Tomographic Scan of brain showed a large subarachnoid cyst with a solid intensely contrast enhancing tumor in the right temporoparietal region with severe degree of mass effect. Craniotomy and total excision of the tumor followed subsequently by subduro-peritoneal shunt for the extracerebral fluid collection was done. The child made good recovery. Histopathology revealed features of desmoplastic infantile ganglioglioma, viz., marked desmoplastic component with glial and neuronal elements. Immunohistochemistry showed positive staining for glial fibrillary acidic protein (GFAP) with areas of synaptophysin and chromogranin positivity. Desmoplastic infantile ganglioglioma is a rare tumor of infancy, which has excellent prognosis after total excision. No adjuvant therapy is required. This is the first Indian report of desmoplastic infantile ganglioglioma out of less than fifty cases reported worldwide.
Collapse
|
38
|
Sangwan VS, Vemuganti GK, Singh S, Balasubramanian D. Successful Reconstruction of Damaged Ocular Outer Surface in Humans Using Limbal and Conjuctival Stem Cell Culture Methods. Biosci Rep 2003; 23:169-74. [PMID: 14748537 DOI: 10.1023/b:bire.0000007690.43273.73] [Citation(s) in RCA: 86] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
When the ocular outer surface is badly damaged, subsequent corneal transplantation fails due to the absence of basal cells that are needed to support the graft. With the realization that the limbus and the conjunctiva have adult stem cells that can be cultured, it has been possible for us to explant culture these on de-epithelized human amniotic membrane, and to graft the resulting viable and transparent epithelium to 125 needy human patients with success. Ultrastructural, histological, biochemical and immunological assays establish the identity of the cells and the tissue formed.
Collapse
|
39
|
Rao CM, Balasubramanian D. Study of a solid-state reaction by photoacoustic spectroscopy. ACTA ACUST UNITED AC 2002. [DOI: 10.1021/j100395a020] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
|
40
|
Kumar C, Balasubramanian D. Structural features of water-in-oil microemulsions. ACTA ACUST UNITED AC 2002. [DOI: 10.1021/j100452a006] [Citation(s) in RCA: 35] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
|
41
|
Balasubramanian D, Misra BC. Chain expansion of neutral polymer coils upon cation binding. ACTA ACUST UNITED AC 2002. [DOI: 10.1021/j100539a026] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
|
42
|
Shobha J, Balasubramanian D. Hairpin looping of terminally functionalized carboxylate surfactants. ACTA ACUST UNITED AC 2002. [DOI: 10.1021/j100404a002] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
|
43
|
Subramanian S, Balasubramanian D, Ahluwalia JC. Nuclear magnetic resonance and thermochemical studies on the influence of urea on water structure. ACTA ACUST UNITED AC 2002. [DOI: 10.1021/j100721a043] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
|
44
|
|
45
|
Balasubramanian D, Srinivas V, Gaikar VG, Sharma MM. Aggregation behavior of hydrotropic compounds in aqueous solution. ACTA ACUST UNITED AC 2002. [DOI: 10.1021/j100346a098] [Citation(s) in RCA: 212] [Impact Index Per Article: 9.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
|
46
|
Balasubramanian D, Guptasarma P, Luthra M. In situ photoreactions of proteins in spectrometers leading to variations in signal intensities. J Am Chem Soc 2002. [DOI: 10.1021/ja00031a050] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
|
47
|
Shobha J, Srinivas V, Balasubramanian D. Differential modes of incorporation of probe molecules in micelles and in bilayer vesicles. ACTA ACUST UNITED AC 2002. [DOI: 10.1021/j100338a007] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
|
48
|
|
49
|
Balasubramanian D, Mitra P. Critical solution temperatures of liquid mixtures and the hydrophobic effect. ACTA ACUST UNITED AC 2002. [DOI: 10.1021/j100484a008] [Citation(s) in RCA: 40] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
|
50
|
Mitra P, Ganesh KN, Balasubramanian D. Amplification of the surface activity of solubilizates in amphiphile aggregates: relevance to studies on micelle structure. ACTA ACUST UNITED AC 2002. [DOI: 10.1021/j150646a030] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
|