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K Chu

Publications and source records attributed to K Chu.

80 records · Page 5Linked to original sources
PubMed1980

In vitro information system for collection and analysis of experimental data.

The In Vitro information System (IVIS) provides for the collection, maintenance, analysis and reporting of mutagenesis data for the In Vitro Carcinogenesis Program of the Carcinogenesis Testing Program in the National Cancer Institute. Initial development or IVIS focused on the microbial mutagenicity assays conducted in a collaborative study in four laboratories. Information is collected about contract management, chemicals, microorganisms strain checks, preparation of activation enzymes, test results, and confirmation of mutation. IVIS provides for editing and maintenance of the information on computers at the National Institutes of Health. Analysis and reporting features were designed to assist both laboratory investigators and NCI staff in evaluating the mutagenic activity of test compounds. The analysis has focused on two principal goals: using the computer to examine the results of each test to determine if the test was adequate for a further statistical analysis; and secondly, if the plate counts are adequate, developing statistics that indicate whether there is a positive or negative trend. Reports have been developed for tabular displays of test results, frequency distributions, dose response graphs and statistical computations.

Bacteria↗
PubMedDate not supplied

Chemical carcinogens. A review and analysis of the literature of selected chemicals and the establishment of the Gene-Tox Carcinogen Data Base. A report of the U.S. Environmental Protection Agency Gene-Tox Program.

The literature on 506 selected chemicals has been evaluated for evidence that these chemicals induce tumors in experimental animals and this assessment comprises the Gene-Tox Carcinogen Data Base. Three major sources of information were used to create this evaluated data base: all 185 chemicals determined by the International Agency for Research on Cancer to have Sufficient evidence of carcinogenic activity in experimental animals, 28 selected chemicals bioassayed for carcinogenic activity by the National Toxicology Program/National Cancer Institute and found to induce tumors in mice and rats, and 293 selected chemicals which had been evaluated in genetic toxicology and related bioassays as determined from previous Gene-Tox reports. The literature data on the 239 chemicals were analyzed by the Gene-Tox Carcinogenesis Panel in an organized, rational and consistent manner. Criteria were established to assess individual studies employing single chemicals and 4 categories of response were developed: Positive, Negative, Inconclusive (Equivocal) and Inconclusive. After evaluating each of the individual studies on the 293 chemicals, the Panel placed each of the 506 chemicals in an overall classification category based on the strength of the evidence indicating the presence or absence of carcinogenic effects. An 8-category decision scheme was established using a modified version of the International Agency for Research on Cancer approach. This scheme included two categories of Positive (Sufficient and Limited), two categories of Negative (Sufficient and Limited), a category of Equivocal (the evidence of carcinogenicity from well-conducted and well-reported lifetime studies had uncertain significance and was neither clearly positive nor negative), and three categories of Inadequate (the evidence of carcinogenicity was insufficient to make a decision, however, the data suggested a positive or negative indication). Of the 506 chemicals in the Gene-Tox Carcinogen Data Base, 252 were evaluated as Sufficient Positive, 99 as Limited Positive, 40 as Sufficient Negative, 21 as Limited Negative, 1 as Equivocal, 13 as Inadequate with the data suggesting a positive indication, 32 as Inadequate with the data suggesting a negative indication, and 48 Inadequate with the data not suggesting any indication of activity. This data base was analyzed and examined according to chemical class, using a 29 chemical class scheme.(ABSTRACT TRUNCATED AT 400 WORDS)

Animals↗
PubMedDate not supplied

A preliminary study of the reliability of immediate vs. delayed interviews of cardiac arrest witnesses.

INTRODUCTION: Methods to characterize the interval between a collapse from cardiac arrest until a 911 call is made have not yet been developed. OBJECTIVE: To determine the concordance of cardiac arrest data obtained by two methods: an immediate nurse interview of out-of-hospital cardiac arrest (OHCA) witnesses, and a follow-up phone interview performed two weeks later. METHODS: This was a prospective study of OHCA witnesses dating from January 1997 to May 1998. Witnesses were briefly interviewed at the time of emergency department presentation, and two weeks later a more lengthy structured phone interview was performed. The authors identified key data elements: 1) was the arrest witnessed? (Wit); 2) was CPR administered prior to EMS arrival? (BCPR); 3) was the first call placed to 911? (c911); and 4) was the estimated collapse to call interval <4 minutes? (ECCI). The analysis utilized Cohen's kappa statistic and Spearman's correlation coefficient. RESULTS: A convenience sample of 42 matched pairs of OHCA cases was analyzed. Kappa statistics for agreement between methods were: 1) Wit(kappa = 0.750), 2) BCPR(kappa = 0.892), 3) c911 (kappa = 0.892), and 4) ECCI(kappa = 0.571, Spearman's 0.528). CONCLUSION: There is good to excellent agreement between immediate and phone interview data retrieval methods. Phone interviews appear to yield data comparable to that with the more difficult and expensive, direct interview method.

Aged↗
PubMedDate not supplied

Mutant allele frequencies in domestic cats of Taiwan.

Preliminary data for Taiwanese cats generally agree with previous findings in far eastern populations, especially Vladivostok. However, surveys are still too few in number to achieve any detailed perspective for this vast region.

Alleles↗
PubMedDate not supplied

Determination of x-ray spectral distribution from transmission measurements using K-edge filters.

Accurate high-resolution x-ray spectral distributions can be obtained with an intrinsic germanium crystal. This technique is difficult to implement since it requires expensive, complicated, and bulky equipment. If energy resolution requirements are relaxed, then the above drawbacks can be overcome and an x-ray spectrometer that is small, inexpensive could be built. A technique that meets these requirements is described here. X-ray spectra with about 7-keV resolution can be achieved by obtaining transmission measurements through a number of different K-edge filters. Using these measurements, a system of equations is set up and solved giving the required spectral distribution. The technique has been tested using 80, 100, and 120-kVcp x-ray beams with total filtrations of 3.78, 5.78, 9.06 mm A1, and 3.78 mm A1 + 0.137 mm Ho. The results show that the calculated spectra closely resemble tabulated spectra. The errors ranged from 3% to 13%. The half-value layers (HVL) were also calculated and compared to the HVL obtained from tabulated spectra and were found to differ by about 7%.

Spectrum Analysis↗
PubMedDate not supplied

Cell-surface expression of complement restriction factors and sialyl Lewis antigens in oral carcinoma: relevance to chemo-immunotherapy.

Oral squamous cell carcinomas overexpress tumor-associated antigens, yet these antigens do not induce an immune-mediated anti-tumor response. The absence of an anti-tumor immune response may be due to poor immunogenicity of the tumor antigens or due to presence of factors that restrict immune functions. We have analyzed the expression of the tumor-associated sialyl LewisA (sLeA) and sialyl LewisX (sLeA) antigens, the complement restriction factors (CD59, CD46 and CD55) and the apoptosis associated factors Fas and Fas Ligand. Sialyl Lewis antigens (sLeA and sLeX), are immunogenic in that they elicit complement-fixing IgM antibodies. These antigens are associated with aggressive invasive behavior, tumor progression and poor disease-free survival of patients with human carcinomas. Human oral squamous carcinoma cell lines, SCC12 and SCC71, were analyzed for the density of Sialyl Lewis antigens, CD59, CD46, CD59, Fas and FasL on the cell surface. Expression of these antigens on the cell surface was determined employing a cell-suspension ELISA with monospecific monoclonal antibodies. In both oral carcinoma cell lines, the density of expression of sLeX was higher than that of sLeA and SCC71 had a very low level of sLeA expression. Both cell lines expressed a high density of CD59 and slightly lower levels of CD46 and CD55 on the cell surface, suggesting that even if host antibodies are accessible to the target antigens such as sLeX, they could not mediate complement-dependent cytotoxicity. The SCC lines expressed very low levels of Fas and FasL indicating that there maybe a lack of these signaling molecules for apoptosis. Our data suggests that passive immunotherapy or tumor killing by antibody-complement interaction may require downregulation of complement restriction factors.

Antigens, CD↗
PubMedDate not supplied

How adequate are state data to support health reform or monitor health system change?

This article reports on results of a 1994 telephone survey sponsored by the Robert Wood Johnson Foundation to obtain better information on state policymakers' views of the quality of state-based health data and selected information on the actual data available. The findings suggest that state policymakers cannot identify easily who and how many are without health insurance coverage, nor do they know exactly how much money is spent in the state on health care and who spends it. They also cannot ascertain quality or consumers' satisfaction with health plans. Funding, lack of comparability across data sets, and the reluctance of providers and insurers to submit required data are perceived as barriers to improving data. Adopting realistic strategies to overcome these barriers may be crucial if states are to assume greater leadership in health policy and in monitoring health system performance.

Cost Control↗