PubMed Health⌕ Search

Biomedical subjects

D F Liberman

Publications and source records attributed to D F Liberman.

17 recordsLinked to original sources
PubMed1991

Synergism between aflatoxins in covalent binding to DNA and in mutagenesis in the photoactivation system.

Aflatoxins (AFs) produce singlet oxygen upon their exposure to UV (365-nm) light. Singlet oxygen in turn activates them to mutagens and DNA-binding species. DNA binding and mutagenesis by AFs were enhanced in D2O as compared to reactions in H2O, and a singlet oxygen scavenger inhibited mutagenesis. DNA photobinding of 3H-AFB1 increased in the presence of unlabeled AFB2, and the addition of AFB2 enhanced mutagenesis by AFB1 in a synergistic manner. These results are compatible with the notion that singlet oxygen, formed by one aflatoxin molecule, can readily activate another aflatoxin molecule. This may bear an environmental implication in that the weakly carcinogenic AFB2, which is often produced in nature together with AFB1, may be important in enhancing the activation of AFB1 by sunlight.

Aflatoxin B1↗
PubMed1988

DNA strand scission and apurinic sites induced by photoactivated aflatoxins.

Covalent binding of photoactivated aflatoxins to DNA in vitro under close-to-physiological conditions resulted in the formation of apurinic sites and in strand scission. Linearized pBR322 DNA was randomly fragmented, and supercoiled DNA was relaxed during the binding reaction. A primary amine facilitated fragmentation and relaxation. Quantitative measurements of relaxation revealed that the probability of a binding event to be converted into a DNA chain break was approximately 3-5% in the absence of a primary amine. The presence of the latter increased the probability approximately 2- to 3-fold. The results are compatible with the model that photoactivated aflatoxins bind to guanines on DNA; some of these guanine adducts are released, creating apurinic sites. The latter are converted into DNa chain breaks at physiological pH and temperature. Thus, apurinic sites and DNA chain breaks must be considered as quantitatively important (genotoxic) DNA damage induced by aflatoxins.

Aflatoxin B1↗
PubMed1988

Biological safety cabinets, decontamination or sterilization with paraformaldehyde.

Bacillus subtilis var. niger spores were used to determine the exposure time for formaldehyde decontamination of biological safety cabinets. Formaldehyde contact times less than 3 hr were insufficient for sterilization. A contact time of 4 hr or more resulted in a reproducible killing of the spore strips placed inside the cabinets. At 6 hr sufficient formaldehyde had diffused through the high efficiency particulate air (HEPA) filter to sterilize the strips with lower spore counts. A minimum of 5 to 6 logs of killing were observed after 4 to 6 hr of treatment.

Bacillus subtilis↗
PubMed1982

Mutagenicity of anthraquinone and hydroxylated anthraquinones in the Ames/Salmonella microsome system.

The mutagenicity of anthracene, anthraquinone, and four structurally similar compounds of each was evaluated in the Ames/Salmonella microsome assay. Anthraquinone was shown to be mutagenic for strains TA1537, TA1538, and TA98 in the absence of rat liver homogenate. The four anthraquinone derivatives tested were mutagenic for TA1537 exclusively. None of the anthracenes exhibited mutagenic activity.

Anthracenes↗
PubMed1979

Studies of human IgM anti-IgG cryoglobulins: II. Isoelectric focusing characteristics of the reactive antigen and residual serum IgG pools.

The co-isoelectric focusing characteristics of the antigen-IgG and residual IgG pools in the serum of patients with mixed IgM:IgG cryoglobulinemia have been determined. The antigen IgG purified from five IgM cryoglobulins and the residual IgG purified from serum depleted of cryoglobulin were radiolabelled and co-isoelectric focused in polyacrylamide gels in order to determine if the IgM anti-globulin reacted in order to determine if the IgM anti-globulin reacted with IgGs having unique physicochemical properties. Electrofocusing profiles of the IgG from four sera showed only minor differences when the antigen-IgG was compared to residual serum IgG. In one instance, the IEF profile of the antigen-IgG pool was markedly restricted and of a different charge dispersion than the residual serum IgG. This correlated with the limited antigenic specificity previously shown for the autologous IgM antiglobulin.

Antibodies, Anti-Idiotypic↗
PubMed1975

Evaluation of a rapid Bauer-Kirby antibiotic susceptibility determination.

To reduce the incubation time requirement in the Bauer-Kirby antibiotic susceptibility test, comparisons were made of the test results at 18 to 20 h (standard) and 7 to 8 h (rapid) utilizing 100 recent clinical isolates. The zone diameters for 664 disks were monitored by using the standard classification: resistant, intermediate, or susceptible. The susceptibility determination was unchanged in 558 out of 664 instances (84.0%). An analysis of the remaining 106 sets revealed that an initial interpretation of intermediate in zone size, subsequently determined resistant or susceptible, accounted for 49 of the observed differences. The reverse changes, initial resistant or susceptible subsequently classified as intermediate, accounted for 20 of the changes. In five instances the interpretation changed from susceptible to resistant; in two cases the interpretation changed from resistant to susceptible. The remaining 30 determinations were classified as indeterminant due to (i) insufficient growth at the early (7 to 8 h) determination, and to (ii) zones which were so large that they could not be measured accurately. The data indicate that zone sizes when measured to the nearest 0.1 mm can be interpreted with reasonable accuracy and the results can be available 10 to 14 h sooner.

Anti-Bacterial Agents↗
PubMedDate not supplied

Containment considerations for the biotechnology industry.

The handling of hazardous organisms or chemical substances in any research and development activity must be performed in such a manner as to minimize worker exposure to these materials. The term containment is used to describe the assemblage of primary and secondary preventive measures that provide personal, experimental, and environmental protection.

Biotechnology↗
PubMedDate not supplied

Risk assessment of biological hazards in the biotechnology industry.

Almost 15 years have elapsed since the discussions of the risk of biotechnology began. The tentative principles proposed years ago, that microorganisms were to be contained through the application of proper procedures and practices, and the use of proper facilities and equipment, and that the level of containment was to be matched to the estimated risk, remain applicable and of value today.

Biotechnology↗