Biomedical subjects

J L McKnight

Publications and source records attributed to J L McKnight.

30 records · Page 2Linked to original sources

PubMed1985

Nucleotide sequence and predicted amino acid sequence of a protein encoded in a small herpes simplex virus DNA fragment capable of trans-inducing alpha genes.

The five alpha genes of herpes simplex virus 1 are the first set of genes to be expressed after infection. Previous studies have shown that alpha genes resident in eukaryotic cells are induced by infection with herpes simplex virus 1 or 2 but not by other herpesviruses and indicate that the alpha trans-inducing factor was a structural component of the virion. This factor induces genes linked to a bona fide promoter and containing at the 5' end a small sequence derived from the promoter-regulatory domains of alpha genes. We report the sequence of a small DNA fragment shown previously to be capable of expressing the alpha trans-inducing factor in transient expression systems. The only gene encoded in its entirety in this fragment is predicted to specify a 479 amino acid protein with a Mr of 53,053. The precise termini of the 1.74-kilobase mRNA specifying this protein were determined in our 5' and 3' S1 nuclease protection studies.

Amino Acid Sequence↗

PubMed1985

Ideology and injury prevention.

Data from a recently completed study of head injuries reveal that many of these injuries, and deaths from these injuries, result from interpersonal violence and automobile accidents. Such injuries are normally difficult to prevent. In this study it was found that much of the interpersonal violence involves family members and many of the vehicle accidents, especially those that result in death, happen to pedestrians. Prevention thus becomes even more difficult. Based upon these data and observations, five categories of prevention strategies are generated and evaluated. It is determined that the four strategies usually within the domain of traditional prevention (inaction, education, legislation, and design alterations) are not likely to prevent many head injuries or injuries in general. A fifth category is thus recommended. This category requires meaningful involvement of people into work that impacts on the social and political reality of their lives. The prevailing ideology of prevention offered by the health professions is considered and is found to be in opposition to our fifth prevention category. The implications of this opposition are examined and the search for improved health is considered in this context.

Craniocerebral Trauma↗

PubMed1985

Prevention and poverty.

How valid, particularly for the large underclass, are prescriptions for health administered by external bureaucracies? In this Perspective, empowerment is identified as the vital precondition for salubrious change, perhaps even survival for this sector.

Health Education↗

PubMed1983

A novel proteolytic activity apparently initiating degradation of beta-galactosidase nonsense fragments in in vitro extracts of Escherichia coli.

Our previous in vivo studies demonstrated that large premature fragments of beta-galactosidase are degraded in Escherichia coli by a common pathway, and the initial event appears to be a site-specific cleavage (McKnight, J. L., and Fried, V. A. (1981) J. Biol. Chem. 256, 9652-9661). We now have developed a cell-free system that retains the specificity of this early cleavage event. Immunochemical techniques were used to isolate and quantitate the polypeptide substrate and products in pulse-chase experiments. The in vitro system has an activity that quantitatively converts the prematurely terminated A polypeptide of the lacZ non-sense mutant CSH-10 to the 90-kilodalton common B polypeptide intermediate observed in vivo. The activity is localized in the cytoplasm since the cleavage reaction is not affected by osmotic shock of whole cells or removal of the membrane fraction from cell-free extracts. The lon mutation capR9, which blocks this degradation pathway in vivo, does not affect the initial cleavage event in cell-free extracts of CSH-10 carrying this mutation. The in vitro cleavage event in extracts of lon+ CSH-10 or the isogenic lon- mutant is not stimulated by addition of ATP, not inhibited by depletion of ATP pools by hexokinase-2-deoxyglucose treatment, and not inhibited by EDTA or phenylmethylsulfonyl fluoride. These results suggest that the ATP-dependent proteolytic activity of the lon gene product does not directly catalyze this primary cleavage event.

Escherichia coli↗

PubMed1981

Limited proteolysis. Early steps in the processing of large premature termination fragments of beta-galactosidase in Escherichia coli.

The mechanism by which large premature termination fragments of beta-galactosidase were degraded in Escherichia coli was studied using quantitative immunoprecipitation techniques. Two different lacZ nonsense mutants which produced apparent primary translation products of 96,000 and 109,000 daltons, respectively, were both shown to produce a second beta-galactosidase-related polypeptide of Mr = 90,000. These 90,000-dalton polypeptides appeared to be the same in both strains since they co-migrated when analyzed as a mixture on sodium dodecyl sulfate-polyacrylamide gels and were indistinguishable when analyzed by one-dimensional peptide mapping. Pulse-chase experiments established a stoichiometric precursor-product relationship between the primary mutant gene products (called the A polypeptides) and the common 90,000-dalton polypeptide (called the B polypeptide). No intermediates were detected between the A and B polypeptides. We propose that there is a common pathway for the degradation of these different large fragments of beta-galactosidase. According to this model, the first step would be a specific endoproteolytic cleavage of the primary translation product which produces the 90,000-dalton polypeptide as a common intermediate. The kinetic analysis demonstrated a first order decay of both A and B polypeptides but, surprisingly, the first order rate constant for the decay of A appeared dependent upon the induction regimen. This result suggested that degradation may possibly be autoregulated either by the intracellular level of A or by other intermediates in the degradation pathway.

Antigen-Antibody Complex↗

PubMed1981

A preliminary ferrographic survey of the wear particles in human synovial fluid.

The technique of ferrography has been applied to the analysis of wear particles in human synovial fluid aspirates. A number of discrete, identifiable classes of wear particles were found, including particles indicative of cutting wear and rubbing wear. The spectrum of particles varied among different groups of patients, suggesting an eventual diagnostic use for this method.

Arthritis, Rheumatoid↗

PubMed1978