Fabrication of sucrose biosensor based on single mode planar optical waveguide using co-immobilized plant invertase and GOD.

In present studies, the new optical sensing platform based on optical planar waveguide (OPWG) for sucrose estimation was reported. An evanescent-wave biosensor was designed by using novel agarose-guar gum (AG) biopolymer composite sol-gel with entrapped enzymes (acid invertase (INV) and glucose oxidase (GOD)). Partially purified watermelon invertase isolated from Citrullus vulgaris fruit (specific activity 832 units mg(-1)) in combination with GOD was physically entrapped in AG sol-gel and cladded on the surface of optical planar waveguide. Na(+)-K(+) ion-exchanged glass optical waveguides were prepared and employed for the fabrication of sucrose biosensor. By addressing the enzyme modified waveguide structure with, the optogeometric properties of adsorbed enzyme layer (12 microm) at the sensor solid-liquid interface were studied. The OPWG sensor with short response time (110 s) was characterized using the 0.2M acetate buffer, pH 5.5. The fabricated sucrose sensor showed concentration dependent linear response in the range 1 x 10(-10) to 1 x 10(-6)M of sucrose. Lower limit of detection of this novel AG-INV-GOD cladded OPWG sensor was found to be 2.5 x 10(-11)M sucrose, which indicates that the developed biosensor has higher sensitivity towards sucrose as compared to earlier reported sensors using various transducer systems. Biochips when stored at room temperature, showed high stability for 81 days with 80% retention of original sensitivity. These sucrose sensing biochips showed good operational efficiency for 10 cycles. The proper confinement of acid invertase and glucose oxidase in hydrogel composite was confirmed by scanning electron microscopy (SEM) images. The constructed OPWG sensor is versatile, easy to fabricate and can be used for sucrose measurements with very high sensitivity.

A disposable optrode using immobilized tyrosinase films.

A disposable fiber-optic sensor based on the immobilized tyrosinase enzyme in a composite biopolymer and its application for the detection of 3,4-dihydroxyphenyalanine (L-dopa) and its analog are described. The enzymatic oxidation product of L-dopa was stabilized through formation of an adduct with 3-methyl-2-benzothiazoline hydrazone resulting in enhanced accuracy and sensitivity of the measurements. The response was found to be linear and concentration dependent in the range of 5 x 10(-5) to 4 x 10(-4) M (r(2) = 0.9307) for the substrate l-dopa over the pH range 5.8 to 7.2 with response times of 8 min. The immobilized enzyme films are stable for 4 months when stored under moisture-free conditions at 4 degrees C.

Effectiveness of heparin in preventing thrombin generation and thrombin activity in patients undergoing coronary intervention.

BACKGROUND: Thrombus is important in the pathophysiology of several complications of angioplasty, including abrupt closure and restenosis. Levels of prothrombin fragment F1.2 and fibrinopeptide A reflect thrombin generation and activity. The effect of angioplasty on levels of these markers is unclear. METHODS: Patients undergoing either balloon angioplasty (n = 30) or directional atherectomy (n = 9) were treated with heparin to maintain an activated clotting time of >300 seconds. Levels of F1.2, fibrinopeptide A, and thrombin-antithrombin complex were measured in the coronary sinus and coronary artery before and after intervention. Angiograms were reviewed for lesion morphologic characteristics and dissection. RESULTS: There was no evidence for thrombin generation or increased thrombin activity after angioplasty regardless of lesion morphologic characteristics, dissection, type of intervention, or blood sampling site. In fact, coronary sinus concentrations of F1.2 decreased after intervention (median 0.31 nmol/L; 25th percentile 0.26 nmol/L, 75th percentile 0.37 nmol/L) before intervention to 0.23 nmol/L (25th percentile 0.19 nmol/L, 75th percentile 0.34 nmol/L) after intervention (P =.002). CONCLUSIONS: Angioplasty performed in the presence of adequate heparin inhibited thrombin even when there was complex lesion morphology or dissection. These data suggest that heparin provides satisfactory thrombin inhibition during routine angioplasty.

Synthesis and Characterization of Coordinatively Unsaturated Copper (II) Complexes of 1,3-Bis(2'-Pyridyl)-1,2-Diaza-2-Butene and Their Antityrosinase Activity.

The coordinatively unsaturated copper (II) complexes of 1,3-bis(2'-pyridyl)-1,2-diaza-2- butene with different ancillary anions were synthesized which can bind to copper centers of tyrosinase enzyme. The compounds were found to exhibit inhibitory activities against mushroom tyrosinase and the nature and extent of inhibition is modulated according to the type of ancillary anions.

Cardiac tamponade in patients infected with HIV. A report from an inner-city hospital.

Thirty-seven consecutive cases of cardiac tamponade occurring over a 6-year period were retrospectively studied from January 1986 to December 1991 in an inner-city public teaching hospital. All episodes were secondary to medical illnesses. Thirteen (35 percent) of 37 patients had HIV infection. Significant differences (HIV vs non-HIV) in clinical presentation were noted in the following parameters: (1) age (34 +/- 7 years vs 56 +/- 14 years, p < 0.001); (2) febrile presentation (62 percent vs 17 percent, p < 0.02); and (3) presence of pulmonary infiltrates (54 percent vs 17 percent, p < 0.03). All but two patients underwent pericardiocentesis or had operative creation of a pericardial window. Two patients had purulent pericarditis; two patients had tuberculous pericarditis. In the remaining patients, there was no evidence of opportunistic infection or malignancy based on cultures of pericardial fluid and histopathologic analysis of tissue. Six of 13 patients with HIV infection survived to be discharged from the hospital following hospitalization for the illness. We conclude the following: (1) HIV infection is frequently found in patients with cardiac tamponade at inner city hospitals; (2) when young patients present with cardiac tamponade, the coexistence of fever and pulmonary infiltrates is suggestive of underlying HIV infection; and (3) the etiology of the pericardial effusion is not confirmed in the majority of patients with HIV infection.

Liquid-liquid extraction of niobium(V) in the presence of other metals with high molecular mass amines and ascorbic acid.

A novel method is proposed for the solvent extraction of niobium(V). A 0.1M solution of Aliquat 336S in xylene quantitatively extracts microgram quantities of niobium(V) from 0.01M ascorbic acid at pH 3.5-6.5. Niobium from the organic phase is stripped with 0.5M nitric acid and determined spectrophotometrically in the aqueous phase as its complex with TAR. The method permits separation of niobium not only from tantalum(V) but also from vanadium(IV), titanium(IV), zirconium(IV), thorium(IV), chromium(III), molybdenum(VI), uranium(VI), iron(III), etc. Niobium from stainless steel was determined with a precision of 0.42%.

Rapid evolution of cardiac tamponade due to bacterial pericarditis in two patients with HIV-1 infection.

We describe two HIV-seropositive patients with acute pneumococcal empyema and pericarditis. Cardiac tamponade evolved rapidly in each patient and was reversed with prompt surgical intervention. In each case, immunologic abnormalities were detected which could have facilitated local spread of infection and progression to tamponade. Pericarditis, an otherwise rare manifestation of pneumococcal infection in the antibiotic era, should be anticipated in HIV-seropositive patients with pneumococcal empyema.

[The relation of uric acid metabolism to transferase activity in patients with ischemic heart disease and hypertension]. / Sviaz' obmena mochevoi kisloty s aktivnost'iu transferaz u bol'nykh ishemicheskoi bolezn'iu serdtsa i gipertonicheskoi bolezn'iu.

Blood plasma uric acid and urea content and aspartate aminotransferase activity were studied in 177 patients with ischemic heart disease and essential hypertension. It was established that the blood uric acid level did not depend essentially on the transamination processes in patients with ischemic heart disease but was closely connected with transamination processes and amino acid metabolism in patients with essential hypertension.

[The role of homeostatic function of the kidneys in the development of hyperuricemia]. / Rol' gomeostaticheskoi funktsii pochek v razvitii giperurikemii.

The content of uric acid in blood plasma has been determined and its relation with the homeostatic renal function has been studied in CHD and hypertensive patients. The attenuation of renal filtration processes has been revealed in a half of the 117 patients. The CHD patients have showed a significant relation between the levels of uric acid and protein in blood. There is an immediate correlation between the uric acid content and alpha 2-globulins in patients with CHD and hyperuricemia. It has been suggested that the development of hyperuricemia in CHD patients is dut to the mechanism of disturbances in binding of uric acid to transport blood proteins.

A simple preparative method for the isolation of amylose and amylopectin from potato starch.

The defatted starch was dispersed in NaOH (1 M) and neutralized with HCl (1 M). The amylose 1-butanol complex is adsorbed on defatted cellulose powder in the solvent system containing acetate buffer (pH 4.8,0.1 M) + urea (2 M) + 1-butanol (8.5%, v/v). The complex adsorbed on cellulose powder is separated by centrifugation (2418 g). The sediment is washed with the solvent system-I to obtain the intermediate fraction. The adsorbed amylose is eluted with urea (2 M) in acetate buffer (pH 4.8, 0.1 M). The amylose, intermediate fraction and amylopectin were precipitated with ethanol, washed free of urea and air dried. They were characterized by determining their blue value and beta -amylolysis limit.

A modified method for the preparation of agarose.

A simple procedure for the preparation of agarose suitable for electrophoresis is developed in which anionic polysaccharides are removed by extracting the agar gel-granules with phosphate buffer (0.03 M, pH 6.8) containing urea (4 M), followed by electrophoresis in the same buffer system. Further, alkali treatment in the presence of sodium borohydride, eliminates electroendosmosis, giving essentially a neutral agarose, as judged by the electrophoretic behaviour of basic substances like crystal violet and cytochrome C. The purified agarose with yields 60-65%, has a sulphur content less than 0.1%, and forms rigid, transparent gels.