Isolation and characterization of pathogenic Vibrio alginolyticus from sea cage cultured cobia (Rachycentron canadum (Linnaeus 1766)) in India.

Mass mortalities of cobia, Rachycentron canadum, sub-adults occurred during August 2013 in cage culture in the Gulf of Mannar, Mandapam Tamil Nadu, India. The epizootic of disease was started with typical classical clinical signs followed by acute mortality. Grossly, severe haemorrhage and congestion were observed in the gastric mucosa. The abdomen was distended with peritoneal fluid. The heart revealed haemopericardium and fibrinous pericardium. Histologically, the gastric mucosa showed severe erosion and necrosis. Haemorrhagic pericarditis and an increased size of the melano macrophage centre (MMC) in the tail kidney were other histopathological changes. Vibrio sp. was isolated from the gastric lesions and heart blood swab of moribund fishes and it was found to be virulent to the cobia fingerlings. After the challenge, the same bacterium could be re-isolated from moribund fingerlings. The 16S ribosomal RNA of the isolate was amplified and blast analysis of the sequence confirmed that the pathogen was Vibrio alginolyticus. The confirmation was also correlated with its cultural, biochemical and pathomorphological changes. This is the second report and the first incidence of epizootics with severe pathological lesions in cultured cobia in India. The study throws light on the pathology of vibriosis. By practising cage farm management measures, occurrences of infection may be prevented. SIGNIFICANCE AND IMPACT OF THE STUDY: The epizootics of vibriosis caused serious economic losses to farmers. Natural blooms of the pathogen can be prevented by sea cage management measures such as, changing the inner net of the cages, changing the location of the cages to relatively clean water (about 50 m apart) from the affected site and providing shade over the cages while the water temperature rises. Supplementation of the feed with immunostimulants and mineral mixture may be practised to improve the immune response against infection. Early diagnosis and sea cage management measures may prevent occurrences of the infection.

Hybrid A­B­A type nanowires through cation exchange.

Hybrid A­B­A type nanowires (NWs) with Ag5Te3­HgTe­Ag5Te3 composition have been created by the reaction of Hg2+ with Ag2Te NWs. The NW morphology of Ag2Te is preserved upon reaction with minor changes and the two separate phases formed are spatially separated within the same NW. The reaction of Hg2+ with Ag2Te NWs was monitored at different concentrations and the reactivity was attributed to cationic exchange depending on solubility products. Hybrid NWs were formed by partial cation exchange only at low concentrations (below 50 ppm) resulting in Ag5Te3 and HgTe within the same NW. However, at high concentrations (above 100 ppm), the HgTe phase alone was formed. These studies have been extended to other metal ions such as Pb2+, Cd2+, and Zn2+ whose reactivity towards Ag2Te NWs is different from that of Hg2+. These ions form a passivating Te oxide layer upon reaction with other metal ions. The mechanism of reactivity of Hg2+ is explained on the basis of free energy of formation of the ionic solid. Phase transition of Hg2+-reacted NWs occurs at a lower temperature than the parent (Ag2Te NWs) and other metal ions-reacted Ag2Te NWs. Details of the process were elucidated using microscopic and spectroscopic investigations. The physical and chemical properties of the individual components within a NW are expected to provide a novel functionality to the metal chalcogenide systems.

Pt3Te4 nanoparticles from tellurium nanowires.

We report the synthesis of platinum telluride nanoparticles (Pt(3)Te(4) NPs) in the solution phase at room temperature using a template-assisted method. The dendrimeric aggregates formed are composed of several small units of Pt(3)Te(4) NPs of ∼4 nm diameter. Tellurium nanowires (Te NWs) are used as the template and the reducing agent in the growth of NPs which occurs due to the galvanic replacement reaction between Te NWs and PtCl(6)(2-). Surface-enhanced Raman scattering (SERS) of the dispersed Pt(3)Te(4) NPs was studied using crystal violet (CV) as the analyte. SERS sensitivity up to 10(-8) M of CV was observed. The Raman enhancement factor (EF) of adsorbed CV on NP aggregates was calculated to be 1.74 × 10(5). The catalytic ability of the as-synthesized Pt(3)Te(4) NPs for the reduction of 4-nitrophenol (4-NP) was studied.

One-, two-, and three-dimensional superstructures of gold nanorods induced by dimercaptosuccinic acid.

A method is described for assembling gold nanorods into one-, two-, and three-dimensional superstructures. The addition of dimercaptosuccinic acid (DMSA) into the nanorod solution was found to induce self-assembly of the latter to one-dimensional "tapelike", two-dimensional "sheetlike" and three-dimensional "superlattice-like" structures depending on the DMSA concentration. The assembly was found to follow a smectic structure, where the nanorod long axes are parallel to each other. The rods are spaced 8.5 +/- 0.3 nm apart in the resulting structures, which extend over several micrometers in length. Organizations perpendicular to the grid were also found. The nanorod tapes were found to bend, and they form circular assemblies as well. The assembly and morphology of the nanorod structures were characterized by transmission electron microscopy and UV-vis spectroscopy. The effect of the DMSA concentration as well as the pH of the medium was also studied. On the basis of several control experiments utilizing similar molecules, charge neutralization of the nanorods by the carboxylic group of DMSA was found to be the principal reason for such an assembly, while the mercapto groups render additional stability to its structure. A mechanistic model of the assembly is proposed. This type of assembly would plausibly function as a plasmonic waveguide in potential nanodevices.

Body- or tip-controlled reactivity of gold nanorods and their conversion to particles through other anisotropic structures.

We report the shape transformation of gold nanorods to spherical nanoparticles, assisted by cupric ions. The reaction proceeds through a series of structures and could be arrested at any stage to produce particles of desired shape. In the presence of a larger concentration of cetyltrimethylammonium bromide (CTAB), selective etching of the tips of the nanorods occurs to a greater extent. The subsequent transformation is driven by the surface reconstruction of nanorods to generate more stable surfaces. As the stability of various surfaces depends on the protecting agent used, the reactivity is modified by controlling its presence at the surface. We show that the body of the rods is more susceptible for reaction at reduced CTAB concentrations. During the conversion to particles, several anisotropic transient structures were observed and were imaged using high-resolution transmission electron microscopy (HRTEM). The transformation occurs due to the hydroxyl radicals produced by Cu2+ in the presence of ascorbic acid (AA). A mechanism has been proposed and several control experiments were conducted to test it. The cupric ion induced shape transformations can be extended to other ions, and knowing the mechanism allows the control of the process to stabilize various anisotropic structures.

Gold nanorods grown on microgels leading to hexagonal nanostructures.

Hexagonal patterns of gold nanorods were made by assembling gold nanorod-coated poly(N-isopropyl acrylamide) microgels. The required population of nanorods on the microgels was achieved by attaching nanoparticle seeds on the latter and growing them to nanorods. The various materials prepared were characterized by UV-vis spectroscopy and transmission electron microscopy. Similar experiments with nanoparticle-coated or prefabricated nanorod-coated microgels did not give such hexagonal patterns. We suggest that the interlocking of nanorods leads to these regular structures. This is the first report of a solution phase method for assembling nanorods into a hexagonal pattern.

Hemoprotein bioconjugates of gold and silver nanoparticles and gold nanorods: structure-function correlations.

Bioconjugates of the hemoproteins, myoglobin, and hemoglobin have been synthesized by their adsorption on spherical gold and silver nanoparticles and gold nanorods. The adsorption of hemoproteins on the nanoparticle surface was confirmed by their molecular ion signatures in matrix assisted laser desorption ionization mass spectrometry and specific Raman features of the prosthetic heme b units. High-resolution transmission electron microscopy (HRTEM) and UV-visible spectroscopy showed that the particles retain their morphology and show aggregation only in the case of silver. The binding of azide ion to the Fe(III) center of the prosthetic heme b moiety caused a red shift of the Soret band, both in the case of the bioconjugates and in free hemoproteins. This was further confirmed by the characteristic signature at 2050 cm-1 in the Fourier-transform infrared spectra, which corresponds to the asymmetric stretching of the Fe(III) bound azide. The retention of the chemical behavior of the prosthetic heme group after adsorption on the nanoparticle is interesting due to its implications in nanoparticle supported enzyme catalysis. The absence of morphology changes after the reaction of bioconjugates with azide ion observed in HRTEM studies implies the stability of nanoparticles under the reaction conditions. All these studies indicate the retention of protein structure after adsorption on the nanoparticle surface.

Randomized control trial of quinine and artesunate in complicated malaria.

OBJECTIVE: To study the comparative efficacy of the quinine and artesunate in complicated malaria in children. METHODS: All cases admitted to the Pediatrics ward of our hospital with clinical features of complicated malaria (WHO criteria) having asexual forms of P. falciparum in the peripheral smear, were included in the study. Relevant investigations were carried out for confirmation of diagnosis and to assess the prognosis. The patients were sub-grouped into 6 categories as per clinical presentations and each subgroup received alternatively either quinine or artesunate by systematic random sample method. Every odd number received quinine (Group-1) and every even number received artesunate (Group-2). 40 cases in each group were considered for the study and the data obtained were compiled and analyzed by suitable statistical tests. RESULTS: 80 children with complicated malaria enrolled in the present study, of which 48 were boys and 32 were girls. The mean age was 7.93+3.56 years. The most common presentations were fever, splenomegaly and altered sensorium. The CRT, FCT and PCT were significantly less in the artesunate group (50.4 +/- 31.49 hrs; 43.55 +/- 20.12 hrs, and 41.67 +/- 16.78 hrs respectively) as compared to the quinine group (70.15 +/- 17.56 hrs, 62.23 +/- 16.99 hrs, and 52.24 +/- 12.69 hrs respectively) ( p<0.05) No side effects were observed in the artesunate treated group. CONCLUSION: Artesunate is a much better drug than quinine in complicated malaria in terms of rapid coma resolution, fever clearance, parasite clearance and better tolerability.

Penetrating atherosclerotic ulcer of the aorta.

PURPOSE: To describe a case of penetrating atherosclerotic ulcer of the aorta with a review of its natural history, diagnosis and management. CASE REPORT: An elderly patient with a history of hypertension presented to the emergency room with the sudden onset of severe chest pain radiating to the back. The electrocardiogram showed left ventricular hypertrophy; the chest radiograph revealed mediastinal widening. Computed tomography was suspicious for a mediastinal hematoma without aortic dissection. Transesophageal echocardiography was also negative for dissection. An aortogram revealed a penetrating atherosclerotic ulcer of the descending thoracic aorta. The patient underwent successful resection and repair of the lesion. CONCLUSIONS: Penetrating atherosclerotic ulcer of the aorta is a potentially lethal lesion that must be promptly diagnosed and treated.

Transesophageal echocardiography in patients with ischemic stroke accurately detects significant coronary artery stenosis and often changes management.

OBJECTIVES: TEE is performed in many patients with ischemic stroke, and it is possible to examine the proximal coronaries by TEE in these patients. Our purpose was to (1) determine the accuracy of transesophageal echocardiography (TEE) in the diagnosis of proximal coronary stenosis in patients with ischemic stroke and (2) show that TEE detection of proximal coronary stenosis changed management in a substantial number of patients. METHODS: Thirty-two patients with ischemic stroke undergoing TEE, in whom the proximal coronaries were examined and who had angiographic results available, were studied. RESULTS: Proximal coronaries were visualized as follows: left main (LM) in 31 (97%), left anterior descending (LAD) in 32 (100%), left circumflex (LCx) in 30 (94%) and right coronary artery (RCA) in 21 (66%). The sensitivity and specificity of TEE in diagnosing significant coronary stenosis in visualized vessels were as follows: LM 100% and 100%, LAD 100% and 95%, LCx 100% and 96%, and RCA 100% and 100%, respectively. When visualized and nonvisualized segments were considered, TEE detected significant stenosis as follows: 4 of 5 in the LM (80%), 13 of 13 in the LAD (100%), 2 of 3 in the LCx (66%), and 2 of 8 in the RCA (25%). Of the 32 patients, TEE results changed management in 17 patients (53%). Angiographic findings resulted in 10 of the 17 patients (59%) undergoing revascularization. CONCLUSIONS: TEE was very accurate in diagnosing significant coexisting coronary artery disease in patients with ischemic stroke. TEE diagnosis of these lesions prompted coronary angiography and subsequent revascularization in a substantial number of patients.

Treatment of femoral artery pseudoaneurysm with percutaneous thrombin injection.

Pseudoaneurysm formation of the femoral artery is a well-known complication following catheter-based vascular procedures. Ultrasound-guided compression or surgical correction are commonly used for its repair. We describe a new method of treatment for femoral pseudoaneurysm. The pseudoaneurysm is visualized by contralateral angiography and thrombosed with a percutaneous thrombin injection while the distal vessel is isolated with a brief balloon inflation. Fluoroscopically guided percutaneous thrombin injection is a promising, minimally invasive technique for the treatment of iatrogenic pseudoaneurysm, especially in patients with compromised distal circulation.

Malabsorption in thyroid dysfunctions.

Studies of intestinal absorptive functions in 11 hyperthyroid and 14 hypothyroid patients showed that steatorrhoea was common in hyperthyroid patients and rare in hypothyroid patients. D-xylose malabsorption was present in both the groups of thyroid disorders being more common in hypothyroid one. Occasionally vitamin B12 malabsorption was found in 2 hypothyroid patients. Jejunal mucosal changes were almost unremarkable. Both fat and carbohydrate malabsorption in both groups of patients appeared to be casually related to the thyroid dysfunction.

Early onset duodenal ulcer with special reference to serum alpha-1-antitrypsin activity.

Thirteen patients of duodenal ulcer, below 20 years of age, ten age and sex matched controls and 17 first probands were studied to find out (i) the special characteristics of this duodenal ulcer subtype and (ii) the serum alpha-1-antitrypsin (alpha-1-AT) activity in these patients and their first probands. Basal and maximal acid output, and serum level of alpha-1-AT were measured, and serum agar gel electrophoresis done, in the above subjects. Special characteristics like positive family history, and high basal (p less than or equal to 0.01) and maximal (p less than or equal to 0.001) acid output were noted in these patients. Serum alpha-1-AT was found to be deficient in nine patients. Five first probands also had the heterozygous level of the enzyme deficiency. Thus, patients of early onset duodenal ulcer seem to have special characteristics with alpha-1-antitrypsin deficiency in them as well as in their first probands.