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Biomedical subjects

K Fong

Publications and source records attributed to K Fong.

46 records · Page 3Linked to original sources
PubMed1980

Effects of sodium arsenite on single-strand DNA break formation and post-replication repair in E. coli following UV irradiation.

A non-lethal dose of sodium arsenite is found to inhibit the formation of single-strand DNA breaks in Escherichia coli WP2 wild-type and WP6 polA strains after UV irradiation. Inhibition of single-strand breakage follows a dose-dependent relationship with respect to increasing sodium arsenite concentration. ATP level in WP2 cells is decreased in the presence of sodium arasenite and therefore the inhibition of DNA break formation may be mediated through lowered ATP levels in the irradiated cells. In the presence of a non-lethal dose of sodium aresenite, post-replication repair in WP2 uvrA strains after UV irradation is also inhibited.

Adenosine Triphosphate↗
PubMed1979

Inhibition of deoxyribonucleic acid repair in Escherichia coli by caffeine and acriflavine after ultraviolet irradiation.

The effects of caffeine and acriflavine on cell survival, single-strand deoxyribonucleic acid break formation, and postreplication repair in Escherichia coli wild-type WP2 and WP2 uvrA strains after ultraviolet irradiation was studied. Caffeine (0.5 mg/ml) added before and immediately after ultraviolet irradiation inhibited single-strand deoxyribonucleic acid breakage in wild-type WP2 cells. Single-strand breaks, once formed, were no longer subject to repair inhibition by caffeine. At 0.5 to 2 mg/ml, caffeine did not affect postreplication repair in uvrA strains. These data are consistent with the survival data of both irradiated WP2 and uvrA strains in the presence and absence of caffeine. In unirradiated WP2 and uvrA strains, however, a high caffeine concentration (greater than 2 mg/ml) resulted in gradual reduction of colony-forming units. At a concentration insufficient to alter survival of unirradiated cells, acriflavine (2 microgram/ml) inhibited both single-strand deoxyribonucleic acid breakage and postreplication repair after ultraviolet irradiation. These data suggest that although the modes of action for both caffeine and acriflavine may be similar in the inhibition of single-strand deoxyribonucleic acid break formation, they differ in their mechanisms of action on postreplication repair.

Acridines↗
PubMedDate not supplied

The prevalence of immunization to Duffy antigens in a population of known racial distribution.

A retrospective study at our hospital determined the race or ethnicity of patients seen in an 8-year period who had formed antibodies to Duffy antigens. During that time, 9876 serologic investigations had been performed as a result of a positive direct or indirect antiglobulin test. Among these samples, sera from 45 previously transfused or pregnant patients contained anti-Fya and two contained anti-Fy3. Twenty-nine of the sera that contained anti-Fya (62%) were from blacks, 12 (25%) were from whites, and 6 (13%) were from Hispanics. Both examples of anti-Fy3 were made by black patients. Red cells (RBCs) from 21 of the black patients were Fy(a-b-), those from 7 were Fy(a-b+), and those from 1 could not be phenotyped. RBCs from 17 of the non-black patients were Fy(a-b+) and those from 1 could not be phenotyped. The population of transfused patients evaluated in this study was 47 percent black, 29 percent white, and 24 percent Hispanic. Calculations based on an expected Fy(a-) frequency of 88 percent in blacks, 33 percent in whites, and 20 percent in Hispanics predict that the racial makeup of the Fy(a-) population at our hospital would be 73 percent black, 18 percent white, and 9 percent Hispanic, which is not significantly different (p = 0.25) from the racial makeup of the patients forming anti-Fya and -Fy3. These data indicate that blacks make antibodies to Duffy antigens as frequently as non-blacks.

Black People↗
PubMedDate not supplied

The relative utility of the autologous control and the antiglobulin test phase of the crossmatch.

A retrospective study of pretransfusion testing records compared the utility of the antiglobulin test (AGT) phase of the crossmatch and the autologous control (autocontrol) for detecting clinically significant alloimmunization to red cells (RBCs). Of 110,780 consecutive crossmatches, 141 were positive after a negative antibody screening test; only 4 of these were due to alloantibodies of potential clinical significance, for a predictive value of a positive AGT crossmatch, after a negative antibody screen, of 2.8 percent (4/141). The frequency of potentially shortened RBC survival was 1 in 27,685 units crossmatched. During a similar period, 56,090 autocontrols were performed with the antibody screen. The autocontrol was positive on 902 samples in which the antibody screen was negative. Antibody identification performed in 684 cases generally yielded only cold or warm autoagglutinins. In 96 cases, some form of alloantibody was detected, but only 25 had potential clinical significance by our criteria. Eight of these alloantibodies had concurrently caused in vivo sensitization of RBCs and were classified as delayed hemolytic transfusion reactions. The predictive value of the autocontrol, calculated as the number of significant alloantibodies detected in autocontrol-positive, antibody-screen-negative samples, was 3.6 percent (25/684). Inspection of these cases revealed 11 in which shortened RBC survival might have resulted if the serologic abnormality had not been detected. Thus, the autocontrol had a slightly greater yield of clinically significant findings than the AGT crossmatch.(ABSTRACT TRUNCATED AT 250 WORDS)

Blood Grouping and Crossmatching↗
PubMedDate not supplied

Prenatal ultrasonic prediction of autopsy-proven pulmonary hypoplasia.

The sensitivity, specificity, and positive and negative predictive values for ultrasound estimation of fetal chest circumference in relation to autopsy-proven pulmonary hypoplasia are described in 58 singleton pregnancies at risk (39 with associated preterm premature rupture of the membranes at 30 weeks' gestation or less and of 12 or more days' duration, and 19 with associated anomalies). The ultrasonographic diagnosis of pulmonary hypoplasia was based on values at or below the lower limit of the 95% confidence intervals (for predicting a future observation) for normal pregnancies for each of the following tests; chest circumference in relation to gestational age and to femur length, for the chest circumference to abdominal circumference ratio and for a combination of the three measurements. At necropsy, the diagnosis of pulmonary hypoplasia was based on lung weight to birthweight ratio or radial alveolar counts. Pulmonary hypoplasia was diagnosed in 16 cases at autopsy. The clinicians and the pathologist were blinded to the ultrasonographic measurements. All tests performed well with a sensitivity of 0.55 to 0.80, specificity of 0.90 to 1.00, positive predictive value of 0.80 to 1.00, negative predictive value of 0.87 to 0.91, and an overall accuracy of 0.87 to 0.91. We conclude that ultrasound measurement of fetal chest circumference is of value with regard to the management of pregnancies at risk for lethal pulmonary hypoplasia.

Abnormalities, Multiple↗
PubMedDate not supplied

The synergy of health promotion practice/research/education.

Many nurses are concerned about the lack of connection among nursing practice, research and education. However, the assumption that nursing practice, research, and education represent separate domains or activities that need to be linked, may well contravene the relational synergy they share. This paper describes a project that sought to illustrate, and further explore, the synergistic, iterative relationship of health promoting practice/research/education. The project revealed how this synergy lives out within the daily practice of frontline practitioners and how the researched knowledge practitioners bring forth through their practice can transform care.

Asthma↗
PubMedDate not supplied

Regulation of natural killer cytotoxicity by recombinant alpha interferons. Augmentation by IFN-alpha 7, an interferon similar to IFN-alpha J.

The structure-function relationship of several recombinant human alpha interferons (IFN-alpha) (IFN-alpha 1, IFN-alpha 2, IFN-alpha 4, IFN-alpha 7, IFN-alpha 2/alpha 1 and IFN-delta 4 alpha 1) was investigated with respect to their ability to augment natural killer (NK) cytotoxicity of human peripheral blood mononuclear cells (PBMC) against hemopoietic tumor cell lines. Although all these IFNs significantly augmented NK cytotoxicity against the K562, Daudi and U937 targets, significant quantitave differences were observed in their ability to augment NK. INF-alpha 4, IFN-alpha 2 and IFN-alpha 2/alpha 1 were able to augment NK at low concentrations (less than 0.1 ng/ml), whereas IFN-alpha 7, IFN-alpha 1 and IFN-delta 4 alpha 1 required significantly higher concentrations (3 ng/ml or higher). The cumulative rank order of INFs on the basis of NK augmenting ability was found to be: IFN-alpha 4 approximately IFN-alpha 2 approximately IFN-alpha 2/alpha 1 greater than IFN-alpha 7 greater than IFN-alpha 1 approximately IFN-delta 4 alpha 1. To determine synergism or potentiation in the ability of IFNs to augment NK cytotoxicity, we investigated the effect of simultaneous, sequential and reversed order of treatment of human PBMC by these IFNs. Such potentiation or synergism was not observed. In addition, all these IFNs were able to augment NK cytotoxicity against targets from malignant melanoma cell lines. IFN-alpha 7 augmented regularly and reproducibly NK cytotoxicity in 15 of 19 normal donors examined (79%). This augmentation was blocked by an anti-IFN-alpha antibody. Concentrations of IFN-alpha 7 as low as 0.06 ng/ml were able significantly to augment NK cytotoxicity of PBMC after incubation for one hour at 37 degrees C. In contrast to these findings, IFN-alpha J, an interferon similar to IFN-alpha 7, has been report to be incapable of augmenting NK cytotoxicity and also of interfering with augmentation of NK by other IFNs. Sequential treatment of PBMC first with IFN-alpha 7 and then with other interferons did not prevent the augmentation of NK. Similarly, simultaneous treatment with IFN-alpha 7 and other interferons did not prevent augmentation of NK. In both treatments IFN-alpha J has been reported to prevent augmentation of NK. IFN alpha J and IFN-alpha 7 differ only by one amino acid, at position 107, where a lysine in IFN-alpha J has been replaced by a glutamic acid in the IFN-alpha 7.(ABSTRACT TRUNCATED AT 250 WORDS)

Amino Acid Sequence↗