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Biomedical subjects

M L Blankenship

Publications and source records attributed to M L Blankenship.

At least 19 recordsLinked to original sources
PubMed1990

Mite dermatitis other than scabies.

Most mites are small, have mouth parts capable of puncturing, feed on tissue fluids, have a high reproductive rate, and are found in all habitats, including human skin. Mites are important causes of cutaneous diseases and are vectors of important infectious diseases. Mite bites should be considered whenever any unexplained cutaneous eruption is presented to the dermatologist. A knowledge of the biology of the mites that can attack humans is important when taking a history and for identifying the etiology. Treatment of the dermatitis is symptomatic, with a cure depending on the identification and eradication of the causative mite.

Animals↗
PubMed1984

Equalization of the inverted repeat sequences of the pseudorabies virus genome by intermolecular recombination.

During a study designed to identify changes in the genomes that are observed in mutant populations of pseudorabies virions, a thymidine kinase-defective population of virions which contains genomes that possess inverted repeated sequences of unequal sizes has been identified. This population of virions has been used to ascertain the mechanism and rates of equalization of the repeats. Results showed that when the virions were passed in cell cultures at high multiplicities of infection (either once or several times), one-half of the molecules had repeats of equal size and one-half had repeats of unequal size. This result is to be expected if conditions allowing a high degree of intermolecular recombination involving exchange of repeats exist. The process of intermolecular exchange of inverted repeats is rapid and the DNA molecules were at equilibrium by the time a virion had produced a small plaque. If the virions were passed in cell culture at low multiplicities of infection, they acquired genomes with equal-size repeats. This is probably due to segregation of the virions which had acquired genomes with equal repeats by recombination; in the absence of coinfection of the cells with virions containing genomes with different repeat sizes, heterogeneity of the repeats could not be generated. The fact that virions containing genomes with equal repeats are usually isolated from nature can thus be attributed to equalization of the repeats which results from intermolecular recombination, followed by segregation. A special mechanism ensuring equalization of repeats, such as one repeat acting as a template for the synthesis (or repair) of the other, need therefore not be invoked.

Animals↗
PubMed1984

Gram-negative folliculitis. Follow-up observations in 20 patients.

Gram-negative folliculitis cleared with antibiotics effective against lactose fermenting-gram-negative rods and Proteus organisms in 19 of 20 patients with acne vulgaris. The systemic antibiotic therapy was discontinued after varying periods and the infection remained clear without further treatment for four to 48 months. Nasal cultures were negative for gram-negative organisms on follow-up repeated culture in 12 patients free of infection.

Adolescent↗
PubMed1984

Differential association with cellular substructures of pseudorabies virus DNA during early and late phases of replication.

Pseudorabies virus DNA synthesis can be divided into two phases, early and late, which can be distinguished from each other on the basis of the structures of the replicating DNA. The two types of replicating virus DNA can also be distinguished from each other on the basis of the cellular substructures with which each is associated. Analysis by electron microscopic autoradiography showed that during the first round of replication, nascent virus DNA was found in the vicinity of the nuclear membrane; during later rounds of replication the nascent virus DNA was located centrally within the nucleus. The degree of association of virus DNA synthesized at early and late phases with the nuclear matrix fractions also differed; a larger proportion of late than of early nascent virus DNA was associated with this fraction. While nascent cellular DNA only was associated in significant amounts with the nuclear matrix fraction, a large part (up to 40%) of all the virus DNA remained associated with this fraction. However, no retention of specific virus proteins in this fraction was observed. Except for two virus proteins, which were preferentially extracted from the nuclear matrix, approximately 20% of all virus proteins remained in the nuclear matrix fraction. The large proportion of virus DNA associated with the nuclear fraction indicated that virus DNA may be intimately associated with some proteins. Indeed, protease-treated, "purified" DNA preparations contained two proteins (15K and 10K) with histone-like properties which were protected by the DNA from deproteinization, probably by virtue of being at the center of the concatemeric tangles of virus DNA. It is possible that these proteins play a role in anchoring virus DNA to the nuclear matrices.

Animals↗
PubMed1984

Deletions in the genomes of pseudorabies virus vaccine strains and existence of four isomers of the genomes.

As part of a study designed to identify the genes responsible for the virulence of pseudorabies virus, we have mapped the genomes of two independently derived vaccine strains (Bartha and Norden) by restriction enzyme analysis. The structures of these genomes have been compared with that of the genome of a laboratory strain previously mapped, of restriction fragments which had been cloned. The genome of the Bartha strain was found to be very similar to that of other pseudorabies virus strains, except that a deletion of approximately 2.7 X 10(6) daltons was found in the unique short (US) region. This deletion was also observed in the genome of the Norden vaccine strain but was not observed in the genomes of any other pseudorabies virus strains that have been studied (more than 20). The genome of the Norden strain differs from that of other pseudorabies virus strains in several other respects as well. The most important difference is that in contrast to all other pseudorabies virus strains analyzed to date, which contain a type 2 herpesvirus DNA molecule (in which the US region only inverts itself relative to the unique long [UL] region), the genome of the Norden strain is a type 3 molecule in which both the US and the UL regions of the genome invert themselves, giving rise to four isomeric forms of the genome. The ability of the UL region to invert itself is probably related to the fact that a sequence normally present in all other pseudorabies virus strains at the end of the UL only is found also in inverted form at the junction of the UL and the internal inverted repeat in the Norden strain.

Chromosome Deletion↗
PubMed1983

Progressive vaccinia associated with combined variable immunodeficiency.

Progressive vaccinia developed in a previously healthy woman following smallpox vaccination and was successfully treated with vaccinia immune human globulin and methisazone. Immunologic evaluation over the next 4 1/2 years revealed evidence for combined variable immunodeficiency with increased numbers of circulating OKT 8 positive (suppressor-cytotoxic T) cells and the virtual absence of OKT 4 positive (helper-inducer T) cells.

Female↗
PubMed1981

Isolation and characterization of a temperature-sensitive uncoating mutant of pseudorabies virus.

During the course of characterizing a series of temperature-sensitive mutants of pseudorabies virus, we found one (designated tsL) that did not produce cytopathic changes in rabbit kidney cells at the non-permissive temperature (41 degree C). Although the mutant adsorbed to and penetrated the cells in a normal fashion, virus RNA was not synthesized at 41 degree C in the infected cells. However, if the cells were first incubated at the permissive temperature (32 degree C), virus RNA synthesis occurred at the non-permissive temperature. This occurred even if, during the incubation period at 32 degree C, the expression of viral functions was prevented by treatment with an inhibitor of protein synthesis. The DNA in tsL virions did not appear in the cell nucleus at 41 degree C, and full, non-enveloped nucleocapsids could be recovered from the cytoplasm of tsL virus-infected cells. These results show that the nucleocapsids of tsL remain intact at the non-permissive temperature and that tsL is an uncoating mutant.

Adsorption↗
PubMed1980

Replication of herpesvirus DNA. V. Maturation of concatemeric DNA of pseudorabies virus to genome length is related to capsid formation.

The maturation of pseudorabies virus DNA from the replicative concatemeric form to molecules of genome length was examined using nine DNA+ temperature-sensitive mutants of pseudorabies virus, each belonging to a different complementation group. At the nonpermissive temperature, cells infected with each of the mutants synthesized concatemeric DNA. Cleavage of the concatemeric DNA to genome-length viral DNA was defective in all the DNA+ ts mutants tested, indicating that several viral gene products are involved in the DNA maturation process. In none of the ts mutant-infected cells were capsids with electron-dense cores (containing DNA) formed. Empty capsids with electron-translucent cores were, however, formed in cells infected with six of the nine temperature-sensitive mutants; in cells infected with three of the mutants, no capsid assembly occurred. Because these three mutants are deficient both in maturation of DNA and in the assembly of viral capsids, we conclude that maturation of viral DNA is dependent upon the assembly of capsids. In cells infected with two of the mutants (tsN and tsIE13), normal maturation of viral DNA occurred after shiftdown of the cells to the permissive temperature in the presence of cycloheximide, indicating that the temperature-sensitive proteins involved in DNA maturation became functional after shiftdown. Furthermore, because cycloheximide reduces maturation of DNA in wild-type-infected cells but not in cells infected with these two mutants, we conclude that a protein(s) necessary for the maturation of concatemeric DNA, which is present in limiting amounts during the normal course of infection, accumulated in the mutant-infected cells at the nonpermissive temperature. Concomitant with cleavage of concatemeric DNA, full capsids with electron-dense cores appeared after shiftdown of tsN-infected cells to the permissive temperature, indicating that there may be a correlation between maturation of DNA and formation of full capsids. The number of empty and full capsids (containing electron-dense cores) present in tsN-infected cells incubated at the nonpermissive temperature, as well as after shiftdown to the permissive temperature in the presence of cycloheximide, was determined by electron microscopy and by sedimentation analysis in sucrose gradients. After shiftdown to the permissive temperature in the presence of cycloheximide, the number of empty capsids present in tsN-infected cells decreased with a concomitant accumulation of full capsids, indicating that empty capsids are precursors to full capsids.

Capsid↗
PubMed1978

Characterization of the replicative structures of the DNA of a herpesvirus (pseudorabies).

The replication of PRV DNA occurs in two phases, early and late. During the early stages of infection newly synthesized DNA is associated with molecules sedimenting with an S-value up to two-fold greater than that of mature viral DNA. These molecules represent unit-size linear or circular molecules, as well as small concatemers in the process of replication. Initiation of replication occurs at a site situated 20 micron from one of the ends as well as at or near the end of the molecules. At later times, newly synthesized DNA is associated with large, "tangled" concatemers containing single-stranded segments of DNA. Our results indicate that at least some of the single-stranded DNA may be produced during the extraction procedure. Analysis of the large, "tangled" concatemers with restriction enzymes shows that they consist of linear arrays of viral DNA molecules.

Centrifugation, Density Gradient↗
PubMed1977

Replication of herpesvirus DNA. III. Rate of DNA elongation.

The rate of pseudorabies virus DNA elongation was measured by three different techniques: density shift experiments, radioautography examined by light microscopy, and radioautography examined by electron microscopy. The rate of the fork movement at 37 degrees C was estimated to be approximately 1 micron/min.

Animals↗