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Biomedical subjects

P Gopalakrishnakone

Publications and source records attributed to P Gopalakrishnakone.

At least 91 records · Page 5Linked to original sources
PubMed1991

Purification and partial characterization of stonustoxin (lethal factor) from Synanceja horrida venom.

1. The lethal factor of the stonefish (Synanceja horrida) venom, designated as the stonustoxin, was purified to homogeneity by a two-step procedure on Sephacryl S-200 High Resolution (HR) gel permeation and DEAE Bio-Gel A anion exchange chromatography. 2. Stonustoxin has a native mol. wt of 148,000 and an isoelectric point of 6.9. 3. SDS-polyacrylamide gel electrophoresis revealed two subunits (designated alpha and beta) with mol. wts of 71,000 and 79,000, respectively. 4. The amino acid composition of both subunits and the N-terminal amino acid sequence of the beta subunit were also determined. 5. Purified stonustoxin had an LD50 of 0.017 microgram/g which is 22-fold more potent than that of the crude venom. 6. The toxin exhibited potent haemolytic activity in vitro and edema-inducing activity with a minimum edema dose (MED) of 0.15 micrograms in mouse paw. The edema effect was not antagonized by diphenhydramine.

Amino Acid Sequence↗
PubMed1990

A computer based colour-photo database system for dangerous animals and plants: academic and public information networks.

A microcomputer based database on dangerous animals and plants with capabilities of displaying real colour pictures of these animals and plants on the computer screen in addition to textual information has been developed and is available for medical doctors and other interested academics and professionals. A similar public information system on dangerous animals and plants, their description, identification, and first aid has been developed in collaboration with the teleview project of Singapore Telecom and will be available to the public soon.

Animals↗
PubMed1990

Unusual aspects of the venom apparatus of the blue coral snake, Maticora bivirgata.

Light and transmission electron microscopic observations of the venom gland of the blue coral snake revealed a main venom gland and a long duct. The main secretory cell showed characteristic features of a protein secreting cell, with small microvilli, and a cytoplasm containing vacuoles and vesicles. Another type of "dark cell" and a third type of "basal cell" were also seen. "Nerve terminals" supplying the gland showed pleomorphic vesicles. The compressor muscle surrounding the venom gland showed the A band, Z disc, and H zone. Satellite cells were seen among muscle fibres. The neuromuscular junctions supplying the muscle showed clear vesicles. Scanning electron microscopy of the fangs showed the entrance lumen, discharge orifice, suture and the dental ridge. These findings are compared with relevant structures in other snake species.

Animals↗
PubMed1990

Response of intraventricular macrophages to crotoxin-coated microcarrier beads injected into the lateral ventricle of postnatal rats.

Crotoxin-coated microcarrier beads were injected into the lateral ventricles of 5 days old postnatal rats. The morphology of the cells attached to the beads at various time intervals was studied by scanning and transmission electron microscopy. Scanning electron microscopy showed that very few cells were associated with the surface of the beads 18 hours after the injection. After 2 days a large number of spherical cells showing blebs and filopodia were attached to the surface of the beads. One week after the injection, these cells became oval and, in longer survival periods between 2 weeks and 30 days after the injection, the cells developed a flattened or angular cell body bearing a number of radiating slender processes. Transmission electron microscopy of the re-embedded materials from animals killed 2 days after the injection showed many cells with an eccentric nucleus containing dense chromatin masses. Their abundant cytoplasm was endowed with a variable number of lysosome-like dense granules and vacuoles. In longer surviving animals, the cells became elongated with scanty cytoplasm showing relatively fewer dense granules and cytoplasmic vacuoles. It is postulated from this study that the cells attached to the crotoxin-coated beads are derived from the intraventricular macrophages. These are functionally active initially in response to the beads injected. With time, however, they undergo morphological alteration and regress into quiescent cells which are microglia-like.

Animals↗
PubMed1988

Infrared sensory neurons in the trigeminal ganglia of the python (Python reticulatus)--a horseradish peroxidase study.

The infrared neurons innervating the 5 maxillary, 6 mandibular and 4 mental pit organs of the python, Python reticulatus, have been identified by means of retrograde transport of horseradish peroxidase. The neurons innervating the first maxillary pit are located in the ophthalmic ganglion; those innervating the second maxillary pit are in both the ophthalmic and maxillary ganglia; the neurons innervating the rest of the maxillary pits are located in the maxillary part of the ganglia. Neurons innervating the mandibular and mental pits are all located in the mandibular part of the ganglia. None of the pits are bilaterally innervated by the trigeminal nerve.

Animals↗
PubMed1988

Electron-microscopical study of the choroid plexus and epiplexus cells in cats following a cisternal injection of crotoxin complex.

The choroid plexus and its associated epiplexus cells in the fourth ventricle in cats were studied with scanning and transmission electron microscopy (SEM, TEM) following a cisternal injection of crotoxin complex (phospholipase A2). In SEM, the epiplexus cells of the control animals were predominantly stellate with long radiating processes. At 2 h after the administration of crotoxin complex, these radiating processes flattened out forming sheet-like membranes covering the ventricular surface of the choroid epithelial cells. The membranous coverings remained extended in 5-hour-survival cats. Numerous blebs of different sizes were observed in areas that were not covered by the cytoplasmic membrane in 5-hour animals. Some of the blebs appeared to have ruptured. In TEM, the microvilli of the choroid epithelial cells in crotoxin complex-treated rats were dilated. The luminal surface of the epithelial cells showed eruption of blebs filled with amorphous materials. Pinocytotic vesicles increased in number in the apical cytoplasm. The lumen of the ventricle often contained portions of cytoplasm believed to be derived from the extrusion of the blebs. These appeared to be engulfed by the overlying epiplexus cells. It was concluded that the injected crotoxin complex stimulated both the secretory as well as pinocytotic activity of the choroid epithelial cells. The phagocytosis of the secretory products from the epithelial cells by epiplexus cells suggests a close functional relationship between the two cell types.

Animals↗
PubMed1987

Effects of phospholipase of Enhydrina schistosa venom on nerve, motor end-plate and muscle of the mouse.

Phospholipase A2 from Enhydrina schistosa (sea snake) venom was administered intravenously or intramuscularly to mice. The effects on the contractile responses and neuromuscular transmission were studied in soleus (a slow-twitch muscle) and extensor digitorum longus (e.d.l.--a fast-twitch muscle). These muscles were also studied by morphological methods which included light and electron microscopy and enzyme histochemistry. There was a rapid and irreversible reduction of resting membrane potentials of muscle fibres of soleus which then failed to contract in response to direct or indirect stimulation. The e.d.l. was less severely affected. Spontaneous and evoked release of transmitter remained detectable at almost all end-plates tested and there was no apparent reduction in the sensitivity of the post-synaptic membrane. Most muscle fibres of soleus but only about 50% of those in e.d.l. became necrotic, the histochemical fibre types 1 and 2A being affected. Electron microscopy showed that in the acute phase (up to 24 h) there were lesions of the plasmalemma and severe disorganization of the internal structure of muscle fibres. In contrast, motor nerve terminals remained intact as did myelinated axons in the intramuscular nerves. There was a transient increase in the number of omega-shaped profiles in the axolemma and of coated vesicles in nerve terminals at 1-3 h, but by 24 h motor nerve terminals were normal in appearance. In regenerated muscle, post-synaptic folds at motor end-plates were reduced in depth and number.

Adenosine Triphosphatases↗
PubMed1987

The structure of the ileofibularis muscle in the turtle Trionyx sinensis.

The ileofibularis muscle of the turtle Trionyx sinensis was examined by light and electron microscopy. Acetylcholinesterase staining showed an "en grappe" type of terminal. The muscle showed succinic dehydrogenase activity with three different types of fibers. The fibers appeared fibrillar type under the electron microscope. Neuromuscular junctions showed the presynaptic portion containing clear vesicles and mitochondria, whereas the postjunctional portion showed only few junctional folds.

Acetylcholinesterase↗
PubMed1987

Neuromuscular disorder in rabbit--a pathological study.

Rabbits affected by a neuromuscular disorder have been observed by light and electron microscopy. The presynaptic portion of the neuromuscular junction showed many changes such as depletion or reduction in synaptic vesicle population, degenerative changes in mitochondria. Intra-muscular axons showed few changes such as disorientation and ramification of neurofilaments. The muscle fibres showed some degenerated fibres and increased collagen around the muscle fibres. Intramuscular blood capillaries also showed proliferation of endothelial cells.

Animals↗
PubMed1986

The structure of the pigment cells in the turtle Trionyx sinensis.

A light and transmission electron microscopic study of the pigment cells (chromatophores) revealed the presence of three types of cells, namely: melanophores, xanthophores or erythrophores, and iridophores. The melanophores contained eumelanin containing organelles, the melanosomes and iridophores showed reflecting platelets, whereas, the xanthophores contained pterinosomes. Quantitatively melanophores appeared in large numbers and were widely distributed, ranging from the skin to many internal viscera, whereas iridophores were few and xanthophores very rare.

Animals↗
PubMed1985

Muscular dystrophy in the duck.

Clinical and gross anatomy features of myopathic ducks are reported. Light microscopic examination of the leg muscles showed necrosis, degeneration and inflammation, and some degree of regeneration was also observed. There was infiltration and replacement of muscle fibres with fibrous tissue. Electron microscopy showed the early stages of myofilament dissolution and accumulation of glycogen in the presynaptic terminal of the neuromuscular junction.

Animals↗
PubMed1985

Epiplexus cells in the embryos of the turtle, Trionyx sinensis.

The epiplexus cells in the embryos of the turtle, Trionyx sinensis were examined in scanning and transmission electron microscopy. Although the cells showed diverse morphological forms, the majority of the cells however had a stellate cell body each with 3-5 radiating long processes with secondary processes terminating on the ventricular surface of the choroid epithelial cells. The cell body was relatively smooth. Occasional epiplexus cells displayed blebs on their cell bodies and processes. In the transmission electron microscope, the nucleus contained coarse chromatin clumps. The cytoplasm was endowed with large lysosomal bodies. Based on these observations, it is suggested the epiplexus cells in the turtle embryos are phagocytic even though most of them probably are at the resting stage.

Animals↗
PubMed1985

Structure and innervation of the tracheal muscles of the white Pekin duck.

The sternotrachealis muscle of the duck, Anas platyrhynchos, was examined by light and electron microscopy. Muscle fibres showed succinic dehydrogenase activity but a definite classification based on this was not possible. Muscle contained fibres with features similar to mammalian slow muscle. Neuromuscular junctions showed the presynaptic portion containing clear vesicles and mitochondria, whereas the postjunctional muscle membrane was smooth without any junctional folds.

Acetylcholinesterase↗
PubMed1985

Experimental clinicopathological study of the Habu (Trimerusurus flavoviridis) venom. I. A light microscopic study of terminal degeneration in some brainstem nuclei of the cat following intracisternal injection of the venom.

Central neurotoxic effect of habu venom was studied in cats after intracisternal injections. Thirteen nuclei from the medulla oblongata, eleven from the pons and ten from the midbrain were observed. In the medulla oblongata, the nuclei most affected were the gracile and cuneate nuclei and the nucleus of the spinal tract of the trigeminal nerve; in the midbrain, degeneration was mainly observed in the superior and inferior colliculi. The present findings are discussed and correlated with the behavioral and physiological changes which have been reported previously.

Animals↗
PubMed1984

Cellular and mitochondrial changes induced in the structure of murine skeletal muscle by crotoxin, a neurotoxic phospholipase A2 complex.

Following a single i.m. injection of a sublethal dose of crotoxin into the hindlimb of mice, degenerative changes were observed in the soleus muscle in the ensuing 72 hr using light and electron microscopy. A similar degree of myonecrosis resulted from the injection of the phospholipase A2 subunit alone, whereas crotoxin reconstituted from a chemically modified phospholipase A2 subunit with low catalytic activity showed weak myonecrosis and the non-enzymic subunit, crotapotin, was inactive. Visible defects of the sarcolemma were associated with underlying necrotic areas and attraction of macrophages. Internally, hypercontraction bands were often present and mitochondria in the rounded, orthodox configurational state contained linear dark bodies as part of their crystal organization. In fibre segments with slow onset of degeneration, many mitochondria additionally contained clusters of electron opaque deposit and in mitochondria, heavily laden with such deposits, energy-dispersive microprobe analysis showed the presence of high concentration of calcium. It was concluded that the primary site of action of crotoxin was hydrolysis of the sarcolemmal membrane and that mitochondrial changes were associated with calcium accumulation in response to an altered internal environment. Regeneration of fibres was rapid.

Animals↗