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PubMed1992

Pro-oxidant effects of normobaric hyperoxia in rat tissues.

Rats were exposed to 100% O2 atmosphere for 12, 36 or 48 h, and their lungs, brain, liver and kidneys were studied for signs of oxidative damage. Oxidative damage at molecular level was estimated by: (1) the appearance of conjugated diene double bonds and (2) the amount of fluorescent chromolipids in lipids extracted from tissues. As important intracellular regulators of oxidative stress, the response of enzymes detoxifying reactive oxygen species was also studied. Macroscopically, the brain and the lungs were most susceptible to oxygen-induced effects. As an indication of oxidative tissue damage, hyperoxia caused accumulation of fluorescent chromolipids in brain and lung tissues, whereas diene conjugation did not reveal any signs of lipid peroxidation. Accumulation of fluorescent chromolipids was most prominent in the brain, where 99 and 138% increases over the control were detected after 36 and 48 h hyperoxia, respectively. Fluorescent chromolipids appeared in urine already before their concentrations were elevated in tissues. The activity of superoxide dismutase in the brain was initially decreased, followed then by a slight induction of activity at the later time-points. Pulmonary and hepatic catalase activities were markedly decreased after prolonged (36 and 48 h) hyperoxia. In conclusion, fluorescent chromolipid formation seems to be a sensitive indicator of hyperoxia-induced oxidative damage in rat tissues. The lipid peroxidation-derived fluorescent chromolipids are eliminated from the body via urinary excretion. Moreover, impaired detoxication of reactive oxygen may be implicated in tissue damage due to hyperoxia.

Animals↗
PubMed1981

Chromogenic substrate spectrophotometric assays for the measurement of clotting function.

Spectrophotometric assays for the measurement of coagulation factor activities in plasma have been developed using a relatively specific chromogenic substrate for thrombin. The tissue-factor-activated assay system involves the activation of factors VII and X and prothrombin. The surface-activated assay system involves the activation of factors XII, PK, XI, IX, VII, X and prothrombin using factors V and VIII as cofactors. The thrombin generated subsequent to activation in these two assay systems is measured via its activity on the chromogenic substrate Sarc-Pro-Arg-pNA. These spectrophotometric assays provide a higher degree of sensitivity as compared with the clotting time assays. The tissue-factor-activated system provides a sensitive method for monitoring coumarin therapy. The surface-activated assay system can detect deficiencies of all the factors measured by the conventional APTT assay system, as well as factor VII. Furthermore, this assay provides a sensitive method for monitoring heparin therapy.

Animals↗
PubMed1994

Azidotetrafluorophenyl retinal analogue: synthesis and bacteriorhodopsin pigment formation.

The retinal derivative, all-trans-9-(4-azido-2,3,5,6-tetrafluorophenyl)-3,7- dimethyl-2,4,6,8-nonatetraenal, was synthesized by two routes as a potential photoactivatable cross-linking agent for studies in bacteriorhodopsin (BR) of the chromophore interaction with its apoprotein. The retinal analogue formed a stable, moderately functional BR pigment confirming that the ring cavity of the retinal binding site has a significant tolerance for derivatization on that portion of the molecule. Attempts to cross-link the azido chromophore to the protein by photoactivation were unsuccessful. The electron delocalization effect of the conjugated polyene side chain of the retinal appears to interfere with the formation or reactivity of the nitrene intermediate to the extent that photoactivated cross-linking is not achieved. These results demonstrate a limitation to the use of fluorinated aryl azides as photoaffinity reagents.

Bacteriorhodopsins↗
PubMedDate not supplied

The epidemiology of non-albicans Candida in oropharyngeal candidiasis in HIV patients.

Oropharyngeal candidiasis (OPC) is the most common fungal infection in patients with HIV infection. Fluconazole has been proven to be very effective in treating this infection, but decreased susceptibility of Candida to this drug has emerged. Certain non-albicans species such as C. glabrata and C. krusei are commonly less susceptible to fluconazole than C. albicans and are being isolated with increased frequency in HIV patients. The purpose of this study was to determine if the presence of non-albicans Candida with OPC in HIV patients had an impact on clinical presentation. This study shows that late-stage HIV patients have a high prevalence of Candida with decreased susceptibility to fluconazole, especially non-albicans species. OPC episodes with non-albicans isolates were more likely to require higher doses of fluconazole to achieve clinical cure. Also, the presence of non-albicans Candida was more frequently associated with severe symptoms.

AIDS-Related Opportunistic Infections↗
PubMedDate not supplied

The relationship between place BANA reactivity and clinical parameters in subjects with mental disabilities.

The purpose of the present investigation was to determine whether subjects institutionalized with mental retardation have a relationship between periodontal clinical parameters and the presence of the BANA-positive periodontal pathogens Porphyromonas gingivalls, Treponema denticola, and Bacteroides forsythus in their subgingival plaques. Fifty institutionalized subjects (25 patients with Down syndrome and 25 subjects with mental retardation) were matched with respect to age and sex. Periodontal clinical parameters (Bleeding on Probing, BOP; Papillary Bleeding Score, PBS; and Probing Depth, PD) were obtained from 6 reference teeth (3, 8, 14, 19, 24, 30). In addition, subgingival plaque samples taken from the same 6 teeth were analyzed for the presence of the BANA-positive species, by means of the chairside BANA test. In both the patients with Down syndrome and the group with mental retardation, the presence of BANA-positive plaques was significantly associated with bleeding on probing (p < 0.05) and increased probing depth (p < 0.01, Chi-square). Analysis of these data indicated that the BANA test could be used in combination with clinical criteria to diagnose a periodontopathy anaerobic infection in institutionalized subjects.

Adolescent↗
PubMed2004

Evaluation of a chromogenic assay to measure the factor Xa inhibitory activity of unfractionated heparin in canine plasma.

BACKGROUND: Unfractionated heparin (UFH) has a complex pharmacologic profile that necessitates patient monitoring to prevent inadequate anticoagulation or overdosage and hemorrhage. Factor Xa inhibitory assays (to measure anti-Xa activity) are used to adjust UFH dosage and define safe and effective regimens for specific thrombotic disorders in humans. OBJECTIVE: In this study, the accuracy, linearity, and clinical utility of a chromogenic assay were assessed for monitoring UFH anti-Xa activity in canine plasma samples. METHODS: A commercial assay (Rotachrom Heparin, Diagnostica Stago, Parsippany, NJ, USA) was used to measure anti-Xa activity in canine plasma samples spiked with different concentrations of UFH. Background absorbance and assay linearity were compared for canine and human plasmas. Percentage recovery of UFH anti-Xa activity and intra- and interassay imprecisions were investigated by multiple measurements of canine plasma to which known amounts of UFH were added. The spiked plasma samples also were used to determine the heparin sensitivity of an activated partial thromboplastin time (aPTT) test. RESULTS: Canine plasma samples were assayed at a higher dilution than were human plasma samples (3:8 versus 4:8) to eliminate higher background anti-Xa activity in canine plasma. Using this modification, the recovery of anti-Xa activity in canine plasma was linear (R2 > .9) at concentrations of 0 - 0.75 U/mL UFH. Intra- and interassay imprecisions for plasma samples containing 0.5 U/mL UFH were <10%, whereas samples containing 0.25 U/mL UFH had imprecisions of 13% and 24%, respectively. The anti-Xa activity range of 0.5 - 0.75 U/mL caused prolongation of aPTTs to 1.5 - 2.5 times the assay mean. CONCLUSION: Plasma anti-Xa activity of dogs treated with UFH can be accurately monitored using this commercially available chromogenic assay.

Animals↗
PubMedDate not supplied

Endotoxin concentrations measured by a chromogenic assay in portal and peripheral venous blood in ten dogs with portosystemic shunts.

A chromogenic Limulus amebocyte lysate assay was used to measure portal and peripheral venous endotoxin concentrations in ten medically managed dogs undergoing surgery for correction of a single extrahepatic portosystemic shunt. In all dogs, both peripheral and portal venous blood samples were obtained at the time of surgical manipulation of the anomalous vessel. In six dogs, peripheral venous samples were obtained an average of 8.0 months after surgery. Five physically normal dogs without biochemical or histologic evidence of liver disease served as controls. Data analysis failed to demonstrate significant differences in peripheral and portal venous endotoxin concentrations between the control and study groups. Postoperatively five of six dogs showed a measurable reduction in peripheral venous endotoxin concentration over intraoperatively obtained values, but the differences were not statistically significant (P = 0.06). Based on results of this study it was concluded that systemic endotoxemia was not present in dogs with a single extrahepatic portosystemic shunt that were medically stable prior to surgery.

Animals↗
PubMed1989

Plasma plasminogen concentrations in clinically normal horses: the effect of age, sex and pregnancy.

Plasma concentrations of plasminogen were determined in 28 clinically normal horses, including 13 adult geldings, five non-pregnant mares, five pregnant mares and five yearlings (two fillies, three geldings). Plasminogen was quantitated by a chromogenic assay based on activation of plasmin by excess urokinase. The overall mean plasma plasminogen for these horses was 2.94 +/- 0.54 CTA units (casein units, as defined by the Committee on Thrombolytic Agents) per ml. There were no significant differences in mean plasma plasminogen values among adult geldings, non-pregnant mares, pregnant mares or yearling horses (P greater than 0.05).

Age Factors↗
PubMed1989

Tension-independent heat in rabbit papillary muscle.

1. Heat and force were measured from isometrically contracting (0.2 Hz) rabbit papillary muscles at 21 degrees C during a single contraction-relaxation cycle using antimony-bismuth thermopiles and a capacitance force transducer. 2. Tension-independent heat (TIH) associated with excitation-contraction coupling was isolated from the initial heat by eliminating tension and tension-dependent heat with a Krebs-Ringer solution containing 2,3-butanedione monoxime (BDM) and mannitol. 3. A strategy for testing the validity of this new method for measuring TIH in heart muscle is described and the test confirms that the BDM-hypertonic solution partitioning method properly estimates the magnitude of the TIH component of initial heat. 4. TIH at the time of complete mechanical relaxation is 1.00 +/- 0.17 mJ/g wet weight and the data suggest that calcium cycling is complete by this time. Conversion of TIH to calcium cycled, assuming that 87% of TIH is due to calcium pumping by the sarcoplasmic reticulum, indicates that approximately 52 nmol calcium/g wet weight are required to support a single cycle of mechanical activity (0.2 Hz, 21 degrees C). 5. The length and frequency dependence of excitation-contraction coupling were demonstrated. TIH is reduced by shortening muscle length and by increasing the interval between stimuli. These steady-state data suggest that only a portion (approximately 40%) of TIH is directly related to activation of the contractile apparatus. 6. TIH in the first twitch following a 45 min rest period is significantly reduced by approximately 30%. 7. With subsequent twitches in the positive treppe following the rest period, TIH does not increase as steeply as expected suggesting that tension rise in twitches 1-10 may be modulated by competitive binding of calcium rather than increased calcium delivery.

Animals↗
PubMed2001

[Detection of TDH-producing Vibrio parahaemolyticus O3:K6 from naturally contaminated shellfish using an immunomagnetic separation method and chromogenic agar medium].

We attempted to isolate TDH-producing Vibrio parahaemolyticus O3:K6 from shellfish. Asari samples were incubated with TSB supplemented with 2% (w/v) NaCl for 6 h, and then the 6-h cultures were incubated with salt polymyxin broth for 18 h. After the two-step enrichment, a 1 ml portion of the culture was treated with magnetic beads coated with K6 antibody for immunoconcentration of V. parahaemolyticus O3:K6. The immunoconcentrated and untreated cultures were plated onto a chromogenic agar and TCBS agar media for isolation of V. parahaemolyticus. TDH-producing V. parahaemolyticus O3:K6 was isolated from 3 out of 66 lots (4.5%) of naturally contaminated Asari. Six of 4,265 colonies suspected as V. parahaemolyticus (0.14%) were TDH-producing V. parahaemolyticus O3:K6.

Agar↗
PubMed2002

[An investigation of non-specific reactions in measurement of plasma (1-->3)-beta-D-glucan].

We investigated the detection of non-specific reaction in measurement of plasma (1-->3)-beta-D-glucan (beta-glucan) by alkaline treatment, chromogenic automated kinetic assay (alkaline-kinetic assay) and dilution and heating method, chromogenic endpoint assay (dilution heating endpoint assay). In this study, we reexamined the values of beta-glucan by both methods with and without 4-amidinophenyl benzoate hydrochloride (APB) as protease inhibitor that blocks Limulus reaction in the 142 serum samples from 142 patients who had been treated and measured beta-glucan in Kawasaki medical school hospital between January 1999 and May 1999. Non-specific reactions were judged by the calculated value under APB additive condition. The non-specific reactions were found in 135 of total 142 samples (95.1%) in the alkaline-kinetic assay while no non-specific reactions were recognized in dilution heating endpoint assay. The alkaline-kinetic assay has been used widely and been evaluated it's usefulness because of good sensitivity. However, we found very high frequency of nonspecific reaction in this method. Further studies are needed to define the reasons of non-specific reaction. On the other hand, although non-specific reactions were not detected in dilution heating end-point assay, it's clinical utilities should be evaluated in future clinical studies.

Adult↗
PubMed2004

[Countermeasures against non-specific reactions in the measurement of beta-glucan in plasma by alkaline treatment, chromogenic automated kinetic assay].

We investigated the detection of non-specific reactions in the measurement of plasma (1-->3)-beta-D-glucan (beta-glucan) and countermeasures against them using alkaline treatment, chromogenic automated kinetic assay (alkaline-kinetic assay). In this study, we reexamined the values of beta-glucan using the alkaline-kinetic assay with and without laminaran oligosaccharides (LO) as a kind of beta-glucan that blocks the Limulus reaction. The materials for this study were 584 plasma samples in which beta-glucan had been measured. These were taken from 232 patients in Kawasaki Medical School Hospital between January 2002 and March 2002. Non-specific reactions were judged by a calculated value under a LO additive condition. Determination as to whether or not the each time course of the Limulus reaction was influenced by a non-specific reaction was also studied by applying a non-specific reaction index set up independently. Non-specific reactions were recognized in 51.9% of the samples (81/156). The amount of non-specific reaction was 9.9 pg/ml or less in major samples. On the other hand, when the cut off value of the index for detection of non-specific reactions was set at 0.5, the sensitivity was 88.9% and specificity was 73.7%. The positive and negative predictive values were 93.5% and 60.9% respectively. Non-specific reactions can be approximately distinguished by applying the non-specific reaction index. By so doing, unnecessary initiation of anti fugal therapy in response to non-specific reactions can be avoided. Further prospective and radical studies of non-specific reactions in the alkaline-kinetic assay are necessary.

Adult↗