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Biomedical subjects

J Wolfson

Publications and source records attributed to J Wolfson.

At least 37 records · Page 2Linked to original sources
PubMed1982

Effects of cost-sharing on users of a state's health service program.

This study analyzed some of the effects of the introduction of cost-sharing on users of the state's health service program. The study population had previously received services at no charge and consisted of people with provider-determined medical need, and included, but was not limited to people in financial need. The study sample was selected from 3 years of program service records (1977-1980). Sampling was random and stratified by key variables. Time-series analysis as well as pre/post-policy comparisons were employed. Analysis of changes in the distributions of service user characteristics and in services provided indicated that use of services was not affected adversely and that lower-income, medically needy people were not deterred from using services following the introduction of cost-sharing. Limitations to the study are reviewed, and implications of using cost-sharing in programs such as Medicaid are considered.

Adolescent↗
PubMed1980

Mycoplasma infection in the immunosuppressed leukemic patient.

A case of severe Mycoplasma sp pneumonia possibly potentiated by methotrexate occurred in a 7-year-old child with leukemia in remission. The case typifies the diagnostic dilemma that frequently occurs in the immunosuppressed host, namely an extensive bilateral pulmonary opacification that can have many causes.

Child↗
PubMed1973

The amplification of ribosomal RNA genes involves a rolling circle intermediate.

During the development of Xenopus oocytes there is a special DNA synthesis that leads to a thousandfold amplification of the genes that code for ribosomal RNA. We have used the electron microscope to study this process. Our primary observation is the presence of ribosomal DNA in rolling-circle intermediates at the time of amplification. We believe that these intermediates are involved in the amplification process, and as such offer the first example of the involvement of a rolling circle in the replication of eukaryotic DNA.

Animals↗
PubMed1972

Adenovirus-2 DNA contains an inverted terminal repetition.

Denaturation and renaturation of the adenovirus-2 chromosome (a duplex rod) generates single-stranded circles of unit length. These circles can be opened into linear DNA molecules by digestion with exonuclease III, indicating that hydrogen bonding between the two ends of an adenovirus strand is responsible for maintaining the rod in a circular state.The formation of adenovirus single-stranded circles, and their sensitivity to exonuclease III, indicate that the mature adenovirus-2 DNA molecule contains an inverted terminal repetition. That is, the base sequence at one end of the molecule is inverted and appears again at the other end of the molecule. This is the first example of such a structure, and its function is unknown.

Adenoviridae↗
PubMed1972

Initiation and reinitiation of DNA synthesis during replication of bacteriophage T7.

In its first round of replication, the T7 chromosome follows a simple pattern, as viewed in the electron microscope. The iniation of DNA synthesis occurs about 17% from the genetic left end of the viral DNA rod. Bidirectional DNA synthesis from this origin then generates a replicating intermediate that we call an "eye form." In the eye form, when synthesis in the leftward direction reaches the left end of the viral chromosome, the molecule is converted into a Y-shaped replicating rod. The remaining growing point continues synthesis rightward, until presumably it runs off the right end of the DNA rod, thus terminating replication. Numerous T7 chromosomes were found in which a second round of replication had begun before the first round had finished. Analysis of these reinitiated DNA molecules showed that the second round of replication, like the first, began 17% from the end of the chromosome and involved bidirectional DNA synthesis.

Centrifugation, Density Gradient↗
PubMed1972

Regions of single-stranded DNA in the growing points of replicating bacteriophage T7 chromosomes.

In partially replicated T7 chromosomes, the points where parental strands are separating and new DNA is being synthesized can be seen in the electron microscope to contain regions of single-stranded template DNA. The single-stranded regions are located on only one of the two daughter arms of the replicating chromosome. Inman and Schnös observed such single-stranded regions in 50% of the growing points of replicating lambda DNA, and, as reported in this paper, we find them in about 85% of the growing points of T7 DNA. Both studies support the conclusion that DNA synthesis involves the direct elongation of one daughter strand in the growing point. Evidently, this elongation is accompanied by the unwinding of the parental double helix to expose a region of single-stranded DNA which is then converted to the duplex state by a discontinuous mechanism involving the synthesis of DNA fragments.

Centrifugation, Density Gradient↗
PubMed1970

The rolling circle for phi X DNA replication. 3. Synthesis of supercoiled duplex rings.

During varphiX duplex ring synthesis, the first supercoils to acquire radioactivity after the addition of tritiated thymidine are labeled only in their negative strands. In longer pulses, this asymmetry of labeling progressively disappears. This finding supports the rolling circle model for DNA replication due to the structural asymmetry of its replicating intermediate, but is not predicted by the Cairns or Yoshikawa models.

Carbon Isotopes↗