671 research outputs found

    Expression of proto-oncogenes and muscle specific genes during cardiac hypertrophy and development in rats and humans

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    A regulatory interdependence of expression of proto-oncogenes and muscle specific genes observed in smooth muscle was examined in cardiac muscle during normal development and hypertrophy both in rats and humans. During normal development in rats, myosin light chain 2 expression is very low at prenatal stages, while c-fos expression starts from the early stages of embryonic development. In aorta constricted rats c-fos induction occurs within 30 min whereas myosin light chain 2 expression is sufficiently high only after 3 or 4 days of post operative period. In the case of humans, the expression of myosin light chain 2 as well as c-fos occurs at high levels during embryonic development. Similar results were obtained with tissue samples obtained from patients with cardiac abnormalities. Induction of the c-fos gene in cultured myocytes by 12-O-tetradeeanoylphorbol 13-acetate has no influence on the expression of myosin light chain 2. These studies were extended with studies on c-myc and Β-myosin heavy chain gene expression which revealed a similar pattern of expression as that of c-fos and myosin light chain 2. These results have indicated that the expression of proto-oncogenes in cardiac muscle may be independently regulated from the expression of muscle specific genes

    Studies on collagen. I. Structure of the collagen group of proteins

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    The paper reports the details of the revised structure of collagen. It is composed of three helical polypeptide chains, each of which has ten residues in three turns of a left-handed helix. The three chains are further wound into a superhelix in the form of interwined coiled coils. The major helix is right-handed and makes one turn in thirty residues. The structure has reasonable hydrogen bonds, two for every three residues. The shree-chain cylindrical rods are stacked together in hexagonal array and stabilised by cross-linkages through hydroxyproline side-groups. In trying to fit these in the lattice, a slight uncoiling of the major helix is required, resulting in a repeat of 618 A along the fibre axis. The proposed structure is in good agreement with the infra-red and X-ray data and also fits in broadly with the amino-acid composition and other properties of collagen

    Results of exploratory trawl fishing on the continental slope of the south west coast of India by M.F.V. 'Kalava'

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    So far, extensive deep sea trawling, in waters beyond 100 fathom depths, has not been attempted in Indian waters except for occasional hauls taken by the INVESTIGATOR (Alcock, 1891-1900) and other Expedition vessels (Gunther, 1887, Max Weber, 1913. Norman, 1939). During March-May 1963 M.F.V. 'Kalava' of the Indo-Norwegian Project, carried out 9 exploratory cruises off Alleppey and Ponnani on the South West Coast of India at depths ranging between 150 to 205 fathoms (274-374 m.). Large quantities of bathypelagic fish were taken during these cruises, in areas on the continental slope (Fig. 1). 24 species belonging to 23 genera and 19 families have already been described by Tholasilingam et al. (1964). Nearly 82% of the catch was represented by about 11 bathypelagic species taken at the rate of up to 496 kg. per hour of trawl, in the richest grounds. Since such occurrence has not been recorded so far, a quantitative assessment of these bathypelagic fishes along with deep sea prawns, lobsters and squids, has been given in the following pape

    Detonator using Nickel Hydrazine Nitrate as Primary Explosive

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    Nickel hydrazine nitrate is an energetic coordination compound having explosiveproperties in between that of primary and secondary. This compound was used to develop a newtype of detonator by replacing the sensitive primary explosive, lead azide in conventionaldetonators and keeping RDX (cyclotrimethylenetrinitramine) as the output secondary explosive.The detonator consists of three regions, viz., initiation, deflagration-to-detonation transition(DDT), and output. The initiation and the electrical rating of 1A/1W no-fire were achieved usinga suitable squib. The DDT and the output were taken care of, by pressing requisite quantitiesof Nickel hydrazine nitrate and RDX, respectively at required densities in a stainless steel stemchannel. The detonator assembly involves crimping the squib and the stem channel in a stainlesssteel housing and applying a suitable resin at the crimped-end for leak tightness. The outputwas assessed from the dent depth on aluminium plate, volume expansion on lead block, and byachieving veloctiy of detonation of 8200 m/s in mild detonating cords, containing 0.95 g/m ofRDX, which indicates full-order detonation. The detonators were tested at system level andfound to perform satisfactorily

    Isolation of ckit-positive cardiosphere-forming cells from human atrial biopsy

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    There is increasing interest in developing cell-based therapies to regenerate functional muscle and blood vessels in infarcted dysfunctional myocardium, using stem cells resident in the adult heart. The objective of our study was to identify an easy and cost-effective method for the isolation and expansion of human adult cardiac-resident stem cells. The cells were isolated from right atrial biopsy samples obtained from patients with ischemic heart disease, who were undergoing coronary artery bypass grafting. Two different isolation methods, enzymatic and nonenzymatic, were employed. The cell yield and cluster formation were not significantly different with either of the techniques used for cell isolation. The nonenzymatic method is recommended because of its simplicity and lower cost compared to the enzymatic method

    Addition of RDX/HMX on the Ignition Behaviour of Boron-Potassium Nitrate Pyrotechnic Charge

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    Boron-potassium nitrate (B-KNO3) (25/75) is a well-known pyrotechnic composition whichfinds application as energy-release system for small-calibre rockets and pyrogen igniters forlarger motors. The decomposition of the oxidiser in this composition is endothermic which canbe activated by the addition of high explosives, which decompose exothermically. This paperdescribes the influence of two nitramine explosives, RDX and HMX, on the ignition characteristicsof B-KNO3 composition using thermogravimetry, differential scanning calorimetry, heat andpressure output measurements. Different compositions were prepared by varying the amount ofRDX/HMX from 10 per cent to 50 per cent. Thermal studies on the B-KNO3/high explosivemixtures reveal that these undergo two-stage decomposition. The first stage corresponds to thedecomposition of high explosive and the second stage corresponds to that of the reaction betweenB and KNO3. Kinetic parameters were calculated for both the stages of TG curves using Coats-Redfern and Mac Callum-Tanner methods. Ignition temperature of B-KNO3 decreases on theaddition of RDX/HMX while the onset of RDX or HMX decomposition is not significantly affectedby B-KNO3. The pressure output of B-KNO3 increases on adding RDX/HMX. The heat outputof B-KNO3 is not much affected by the addition of RDX or HMX, even though the heat ofexplosion of RDX and HMX are low. This is due to the reaction between the combustion productsof RDX/HMX and reaction products of B-KNO3 to form more exothermic products like B2O3,releasing extra heat. The flame temperature of the charge increases while the average molecularweight of the products of combustion decreases as the RDX/HMX content increases. Thus, thecharge, on addition of RDX or HMX, produces higher pressure output, maintaining the heatoutput at comparable levels

    Seismic Pounding of Bridges due to Multi-Support Excitation with traveling wave

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    Abstract: -Among structural damages, seismic induced pounding has been commonly observed in severalearthquakes. When lateral and transverse movement of a structure occurs during earthquakes, it will hit adjacent structure and bounce back. This back and forth hitting of adjacent structures is known as pounding. The earthquake ground motion is usually assumed as uniform dynamic motion in seismic analysis. This assumption may be inadequate for structures placed at large areas like bridge, dam etc. Pounding in bridges is a result of the relative movement of the adjacent bridge superstructures at the expansion joints. This movement depends on different structural dynamic properties of the adjacent spans and characteristics of ground motions at the pier supports along the bridge. This paper includes a study of effect of pounding between bridge superstructures under the action of earthquake motion having multi-support excitation with traveling effect. The present study is a numerical investigation of pounding effect on a simply supported bridge using finite element method, using the software, OpenSees

    Tweed in Martensites: A Potential New Spin Glass

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    We've been studying the ``tweed'' precursors above the martensitic transition in shape--memory alloys. These characteristic cross--hatched modulations occur for hundreds of degrees above the first--order shape--changing transition. Our two--dimensional model for this transition, in the limit of infinite elastic anisotropy, can be mapped onto a spin--glass Hamiltonian in a random field. We suggest that the tweed precursors are a direct analogy of the spin--glass phase. The tweed is intermediate between the high--temperature cubic phase and the low--temperature martensitic phase in the same way as the spin--glass phase can be intermediate between ferromagnet and antiferromagnet.Comment: 18 pages and four figures (included

    Measurements of plasma temperature and electron density in laser-induced copper plasma by time-resolved spectroscopy of neutral atom and ion emissions

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    Plasma produced by a 355 nm pulsed Nd:YAG laser with a pulse duration of 6 ns focussed onto a copper solid sample in air at atmospheric pressure is studied spectroscopically. The temperature and electron density characterizing the plasma are measured by time-resolved spectroscopy of neutral atom and ion line emissions in the time window of 300-2000 ns. An echelle spectrograph coupled with a gated intensified charge coupled detector is used to record the plasma emissions. The temperature is obtained using the Boltzmann plot method and the electron density is determined using the Saha-Boltzmann equation method. Both parameters are studied as a function of delay time with respect to the onset of the laser pulse. The results are discussed. The time window where the plasma is optically thin and is also in local thermodynamic equilibrium (LTE), necessary for the laser-induced breakdown spectroscopy (LIBS) analysis of samples, is deduced from the temporal evolution of the intensity ratio of two Cu I lines. It is found to be 700-1000 ns
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