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At least 181 records · Page 10Linked to original sources
PubMed1984

A spectroscopic technique for evaluating sterol-aponin interactions and implications for management of Ptychodiscus brevis red tides.

A double-beam quadruple-cell spectrophotometric technique is described that can be used to evaluate the interaction between sterols and HPLC fractions from Nannochloris sp. which are cytolytic (aponin) toward the red tide organism. The interaction with ergosterol but not beta-sitosterol is consistent with complex formation and also with the reduction of cytolytic activity of aponin in the presence of ergosterol, as previously noted. Implications for the mechanism of aponin cytolytic activity are considered.

Cholesterol↗
PubMed1995

Continuous quality improvement: a tide whose time has come.

Hospitals and physicians need to learn more about continuous quality improvement (CQI). Hand-in-hand with CQI is total quality management (TQM). Physicians must move with the tide of quality improvement, with all its implications. The author offers a primer on CQI.

Total Quality Management↗
PubMed1998

Nutrient regeneration in coastal seas by Noctiluca scintillans, a red tide-causing dinoflagellate.

Ammonium nitrogen, phosphate, and silicate contents in Noctiluca scintillans cell fluid were estimated at 2470, 183, and 54 pmol per individual, respectively. Ammonium nitrogen and phosphate concentrations at the surface layer of the water column seemed to be related to cell abundance of N. scintillans at the sampling location. Patches of N. scintillans provided 16 and 25 times greater concentrations of ammonium nitrogen and phosphate in the uppermost layer (0-10 cm depth) of the water column than those in the ambient seawater, respectively. Silicate concentration within patches, however, was close to that in surrounding water. The morphology of fecal pellets of N. scintillans fed on the diatom, Thalassiosira sp., was examined with a scanning electron microscope. The fecal pellet was composed entirely of visible structural diatom cells. It could be inferred that N. scintillans excretes silica from the diatom undigested in its fecal pellets and thus no remarkably high silicate concentration within red tide patches was observed.

Journal Article↗
PubMedDate not supplied

Time and tide.

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Anecdotes as Topic↗
PubMed1996

Directly observed preventive therapy. Turning the tide against tuberculosis.

OBJECTIVE: To compare compliance between directly observed preventive therapy and daily treatment for students with inactive (class II) tuberculosis. DESIGN: Cohort analytic study and cost-effectiveness analysis. Students found to be positive for purified protein derivative and having no abnormal chest x-ray films on mandated screening were advised to have prophylactic treatment with isoniazid. Treatment was either directly observed in the school health clinic or provided as daily therapy by the Department of Health. Treatment completion, age, sex, ethnicity, and recent immigration were compared between the 2 treatment groups. SETTING: A school-based clinic at an inner-city New York, NY, high school. RESULTS: In 1993, 864 students were screened. The positive purified protein derivative rate was 19.3%. All 161 students had negative findings on chest x-ray films. Of the students, 105 (65.2%) were enrolled in the school-based clinic directly observed preventive therapy program, 22 were referred to the Department of Health for daily therapy, and 34 excluded from the study before treatment. The 2 treatment groups did not differ in composition. Completion of therapy in the directly observed preventive therapy group (87.6%) was significantly greater than that in the daily therapy group (50%) (P = 0.001, X2 = 11.8) and that reported in the literature for programs other than directly observed preventive therapy (30%-70%). Directly observed preventive therapy was administered by existing personnel without additional expenditure. CONCLUSION: Directly observed preventive therapy is an effective strategy that should be used in the school clinic setting to increase compliance with prophylactic treatment for tuberculosis.

Adolescent↗
PubMed1953

Time and tide.

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Education, Medical↗
PubMed1999

Monitoring brevetoxins during a Gymnodinium breve red tide: comparison of sodium channel specific cytotoxicity assay and mouse bioassay for determination of neurotoxic shellfish toxins in shellfish extracts.

In October of 1996, a Gymnodinium breve bloom occurred in shellfish harvesting waters of Alabama, Mississippi and Louisiana, Gulf of Mexico, USA. Bloom densities reached 5.6x10(5) cells liter(-1) and bloom residence at shellfish sampling stations ranged from 3 to 28 days. Brevetoxin-2 dominated G. breve toxin profiles in bloom seawater extracts. Shellfish toxicity, assessed by mouse bioassay, exceeded the guidance level for up to 75 days after the bloom had dissipated. Cytotoxicity assays and mouse bioassays showed similar temporal patterns of shellfish toxicity, but the two methods differed in estimations of brevetoxin-3 equivalent toxicity by a factor of 93 to 1. LC-ESI-MS showed the temporal patterns in shellfish toxicity reflected metabolism of G. breve toxins. The molecular ions m/z 1004, 1017 and 1033 dominated LC-ESI-MS spectra of toxic chromatographic fractions from the extracts and were identified as brevetoxin metabolites on the basis of LC-APCI-MS-MS. The discrepancy between cytotoxicity and mouse bioassay estimates of brevetoxin-3 equivalent toxicity resulted from the difference in extraction efficiency of solvents used in the respective methods and the relative sensitivity of the assays to toxin metabolite mixtures present in the extracts. The normalized cytotoxicity assay showed 75% agreement with mouse bioassay positive test samples and 64% agreement with mouse bioassay negative test samples. Published in 1999 by John Wiley & Sons, Ltd.

Animals↗
PubMed2001

Survey of the distribution of red tide toxins (okadaic acid and dinophytoxin-1) in the Dalian Bay sea area of China by micellar electrokinetic capillary chromatography.

Two kinds of diarrhoetic shellfish toxins, okadaic acid (OA) and dinophytoxin-1 (DTX-1) were determined by micellar electrokinetic capillary chromatography (MEKC) with ultraviolet detection. A detection limit of 3.25 microg/mL for both of them was achieved. The UV absorbance of these toxins measured at 200 nm showed good linearity in the range of 6.25-200 microg/mL with R = 0.992 for OA and 0.997 for DTX-1. Three kinds of shellfish (Chlamys farreri, Mytilus edulis and Ruditaps philippinarum) collected from eight locations (sampling in the intertidal zone) along the Dalian Bay sea area of China were surveyed in February and May of 2000. Results indicated that three kinds of shellfish were contaminated by OA and DTX-1. Based on per gram of hepatopancreas in February, the contamination contents ranged from 0 to 1.26 microg for OA and from 0 to 1.82 microg for DTX-1, and in May, the contents ranged from 0 to 1.45 microg for OA and 0 to 2.56 microg for DTX-1. Among the eight locations, Hei Shi Jiao and Long Wang Tang were the most contaminated areas. Of the three kinds of shellfish, Mytilus edulis was the most significant species in accumulating OA and DTX-1.

Animals↗
PubMed2002

Proteomic study of a model causative agent of harmful red tide, Prorocentrum triestinum I: Optimization of sample preparation methodologies for analyzing with two-dimensional electrophoresis.

A comprehensive study to find the optimal sample preparation conditions for two-dimensional electrophoresis (2-DE) analysis of Prorocentrum triestinum, a model causative agent of harmful algal blooms (HABs) was carried out. The four major sample preparation steps for 2-DE: (a) cell disruption: i.e. sonication and homogenization with glass beads; (b) protein extraction : i.e. sequential and independent extraction procedures; (c) pre-electrophoretic treatment: these included (i) treatment with RNAase/DNAase or benzonase; (ii) ultracentrifugation to sediment large macromolecules such as DNA; (iii) desalting and concentration by ultrafiltration through a Microcon centrifugal filter device (MWCO: 3000 daltons); and (iv) desalting by a micro BioSpin chromatography column (MWCO: 6000 daltons); and (d) rehydration buffers, reducing agents and sample application in the first dimension isoelectric focussing were studied. Our results showed that sonication is easy to perform and resulted in a higher protein yield. Among the four extraction buffers, the urea containing buffers resulted in the extraction of the highest amount of protein while tris(hydroxymethyl)aminomethane buffers and trichloroacetic acid (TCA)/acetone precipitation allowed detection of a higher number of protein species (i.e. protein spots). Desalting by BioSpin and ultrafiltration have improved the 2-DE resolution of the water soluble fraction but have less effect on urea containing fractions. TCA/acetone precipitation was able to desalt all protein fractions independent of the extraction media, however extended exposure to this low pH medium has caused protein modification. Introduction of either DNase/RNase or benzonase treatment did not improve the discriminatory power of the 2-DE but this treatment did yield 2-DE with the clearest background. Proteolytic digestion was inhibited by addition of a protease inhibitor cocktail. Taken overall, a combination of sequential extraction and desalting by BioSpin chromatography for sample treatment before first dimension of 2-DE gave best results based on its simplicity and minimal protein loss. Finally, triscarboxyethylphosphine (TCEP) has performed well as a reducing agent in both the rehydration and equilibration buffers. The rehydration buffer found to be best in this study was 8.0 M urea, 2% 3-[(3-cholamidoprphyldimethylamino]-1-propanesulfonate, 4 mM TCEP and 1% immobilized pH gradient buffer. Subsequently, we applied this finding and performed 2-DE analysis on the soluble protein fractions extracted from light-starved cultured algal cells (nonblooming) and cultured cells grown under optimal conditions (blooming). 2-DE maps of these algal cultures were visibly different and many differentially expressed proteins were found.

Acetone↗