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Biomedical subjects

R N Paul

Publications and source records attributed to R N Paul.

11 recordsLinked to original sources
PubMed2002

Phytotoxicity and ultrastructural effects of gymnopusin from the orchid Maxillaria densa on duckweed (Lemna pausicostata) frond and root tissues.

Two phenanthrene derivatives, characterized as erianthridin (9,10-dihydro-2,7-dihydroxy-3,4-dimethoxyphenanthrene) and gymnopusin (2,7-dihydroxy-3,4,9-trimethoxyphenanthrene), were isolated from an extract of the orchid Maxillaria densa, using phytotoxicity with amaranth (Amaranthus hypochondriacus) to guide fractionation. Gymnopusin and erianthridin inhibited radicle elongation of A. hypochondriacus seedlings with IC(50) values of 330 and 58.2 microM, respectively. The phytoxicity of the two phenanthrene derivatives was also assessed on duckweed (Lemna pausicostata), and compared with mammalian toxicity estimated in vitro with four mammalian cell lines. On duckweed, both phenanthrene derivatives caused electrolyte leakage, chlorophyll loss and photobleaching. Ultrastructural examination of duckweed frond and root tissues treated with gymnopusin (100 microM) revealed membrane damage to the tonoplast after 12 h of exposure. Effects on membrane integrity followed a time course similar to that of electrolyte leakage. Both phenanthrene derivatives exhibited moderate cytotoxicity to all mammalian cells tested, which precludes their use as a bioherbicide.

Amaranthus↗
PubMed1998

Ultrastructural effects of AAL-toxin TA from the fungus Alternaria alternata on black nightshade (Solanum nigrum L.) leaf discs and correlation with biochemical measures of toxicity.

Ultrastructural effects of AAL-toxin TA from Alternaria alternata on black nightshade (Solanum, nigrum L.) leaf discs and correlation with biochemical measures of toxicity. In black nightshade (Solanum nigrum L.) leaf discs floating in solutions of AAL-toxin TA (0.01-200 microM) under continuous light at 25 degrees C, electrolyte leakage, chlorophyll loss, autolysis, and photobleaching were observed within 24 h. Electrolyte leakage, measured by the conductivity increase in the culture medium, began after 12 h with 200 microM AAL-toxin T(A), but was observed after 24 h with 0.01 to 50 microM AAL-toxin T(A), when it ranged from 25%) to 63% of total releasable electrolytes, respectively. After 48 h incubation, leakage ranged from 39% to 79% of total for 0.01 to 200 microM AAL-toxin T(A), respectively, while chlorophyll loss ranged from 5% to 32% of total, respectively. Ultrastructural examination of black night-shade leaf discs floating in 10 microM AAL-toxin TA under continuous light at 25 degrees C revealed cytological damage beginning at 30 h, consistent with the time electrolyte leakage and chlorophyll reduction were observed. After 30 h incubation chloroplast starch grains were enlarged in control leaf discs, but not in AAL-toxin T(A)-treated discs, and the thylakoids of treated tissue contained structural abnormalities. After 36-48 h incubation with 10 microM AAL-toxin T(A), all tissues were destroyed with only cell walls, starch grains, and thylakoid fragments remaining. Toxicity was light-dependent, because leaf discs incubated with AAL-toxin T(A) in darkness for up to 72 h showed little phytotoxic damage. Within 6 h of exposure to > or =0.5 microM toxin, phytosphingosine and sphinganine in black nightshade leaf discs increased markedly, and continued to increase up to 24 h exposure. Thus, phy siological and ultrastructural changes occurred in parallel with disruption of sphingolipid synthesis, consistent with the hypothesis that AAL-toxin T(A) causes phytotoxicity by interrupting sphingolipid biosynthesis, thereby damaging cellular membranes.

Alternaria↗
PubMed1984

Ruptured sinus of valsalva aneurysm in children: report of two cases and literature review.

Two children with ruptured sinus of Valsalva aneurysm are described, each with a ventricular septal defect, and in one there was also an associated discrete subvalvular aortic stenosis. The diagnostic appearance of two-dimensional echocardiography and axial angiocardiography are emphasized to allow early diagnosis and surgical repair. A literature review of recent reports in English disclosed that 13 patients under age 20 had been reported to have ruptured sinus of Valsalva aneurysm.

Adolescent↗
PubMed1983

Techniques for preparing seeds with water-impermeable coats for light and electron microscopy.

An improved method for fixing and embedding seeds with impermeable coats for microscopic study has been developed. Entry portals are cut into seed coats to permit better penetration of fixative. This makes it possible to obtain semithin sections of whole seeds for light microscopy and thin sections of selected areas for electron microscopy. Seed tissues may thereby be studied relative to their position in the seed and to surrounding tissues. This permits studies of inhibition and developmental morphology of seeds in histological and cytological detail previously possible only with soft dissected seeds.

Fixatives↗
PubMed1983

Modified Shumacker repair of transposition of the great arteries. Surgical and angiocardiographic considerations.

Sixteen patients with transposition of the great arteries, 8 days to 2 1/2 years of age, underwent intra-atrial transposition of venous return by the modified Shumacker technique. A bipedicle flap of right atrial wall was used to direct vena caval return to the mitral valve, and a hinged viable flap of pericardium was used to form the lateral wall of the pulmonary venous pathway. Thirteen patients survived operation and are well to date. Two of the three nonsurvivors were less than 1 month of age at operation, and the third had an associated inlet ventricular septal defect and a straddling tricuspid valve. Early postoperative chest radiographs were compared with preoperative films in each patient. Postoperative findings included minor right pleural effusion in four, minor pneumothorax in two, and paralyzed right hemidiaphragm in one. Two patients required a permanent pacemaker because of the development of sick sinus syndrome 2 and 4 years postoperatively. Each preoperative angiocardiogram was reviewed and compared with postoperative studies in nine patients. The latter demonstrated absence of caval gradients in each, trivial baffle leaks in four, a moderate baffle leak in one, small residual ventricular septal defects in two, and mild tricuspid regurgitation in two patients.

Angiocardiography↗
PubMedDate not supplied

A double-blind randomized clinical study of the safety, tolerability and efficacy of Hexabrix in pediatric angiocardiography.

Hexabrix, a low-osmolality radiographic contrast agent consisting of the meglumine and sodium salt of ioxaglic acid (600 mOsm/kg), was evaluated in 50 children undergoing cardiac catheterization in a randomized double-blind manner. In comparison with a conventional radiographic contrast agent (Renografin-76), Hexabrix produced a marked reduction in the pain or discomfort after the injection. Neither agent produced any significant change in pulse or respiratory rates or blood pressure. Changes in left and right ventricular pressures were small and comparable for both groups. Significant dysrhythmias were not noted. There was no evidence of deterioration in renal or hepatic function in either group. Serum LDH and CPK increased comparably with both contrast agents but without any definite evidence of myocardial injury. Postinjection increases in serum osmolality were slightly, but not significantly, higher with Renografin. In the first few hours following the procedure there was an increase in circulating segmented neutrophils and a reciprocal decrease in lymphocytes; this was transient and gone by 24 hours. Radiographic image quality was judged good or excellent in almost all cases. Hexabrix is a contrast agent that is significantly better tolerated than conventional agents and is associated with no greater incidence of side-effects while producing radiographic images of equivalent quality.

Adolescent↗