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Biomedical subjects

A H Fried

Publications and source records attributed to A H Fried.

9 recordsLinked to original sources
PubMed1999

Malignant glial tumor arising from the site of a previous hamartoma/ganglioglioma: coincidence or malignant transformation?

Gangliogliomas are generally considered benign tumors. Although more commonly found in the brain, spinal cord ganglioglioma is a well established, albeit infrequent, entity. We describe a 2-decade clinical course of a patient initially diagnosed with a thoracolumbar 'glial-neuronal hamartoma' at age 4. Seventeen years after his first operation, local recurrence was noted. Despite subsequent multiple gross total resections and adjuvant therapy, histologic features became increasingly ominous and ultimately proved fatal. This is an unusual report and histologic presentation of a resected spinal cord ganglioglioma recurring as an anaplastic ependymoma/astrocytoma and subsequently a glioblastoma. It is quite likely that the originally resected ganglioglioma was actually part of a primitive neuroectodermal tumor which had undergone extensive maturation.

Adult↗
PubMed1998

Patenting genes.

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Genes↗
PubMed1979

Evidence that the RNA polymerase usually does not make a complete transcript of the late strand of simian virus 40 DNA.

An important model for the transcription of the late (L) strand of simian virus 40 DNA is that, late after infection of permissive monkey cells, the RNA polymerase makes a complete transcript of the L DNA strand before terminating transcription. The purpose of the current work was to test a prediction of this model, namely, that the rate of synthesis of all RNA sequences from the L DNA strand should be equal. About one-half of the L DNA strand is transcribed into late mRNA sequences and the other half into late dRNA sequences, which do not leave the nucleus. Using glucosamine to reduce the size of the intracellular UTP pool before and after a pulse-label with radioactive uridine, a pulse-chase experiment was performed to determine the half-lives of these sequences. The half-life of the late dRNA sequences was determined to be 4 min. The late mRNA sequences were degraded more slowly, on the average, than the late dRNA sequences. In a parallel experiment with similarly treated cells, it was shown that after a 2-min label with radioactive uridine there was only 0.2 times as much radioactivity in the late dRNA sequences as in the late mRNA sequences in the total cellular RNA population. The results could be combined to calculate that the rate of synthesis of the late dRNA sequences was at most 0.3 times that of the late mRNA sequences. Consequently they provide strong evidence that when the RNA polymerase transcribes the late mRNA sequences, it usually terminates transcription before all the late dRNA sequences are transcribed.

Base Sequence↗
PubMed1975

Temperature dependence of strand separation of the DNA molecules containing integrated SV40 DNA in transformed cells.

It has previously been demonstrated that the DNA molecules containing a genetic marker from one region of a bacterial genome undergo complete strand separation at temperatures usually different from the molecules containing a genetic marker from another region of the genome. The experiments also showed that if a group of molecules undergo complete strand separation over a narrow temperature range, of the order of one to three degrees, it is highly likely that they all come from one region of the bacterial genome. The purpose of the work reported here was to establish appropriate procedures for doing a similar analysis of the DNA molecules containing the integrated SV40 DNA in transformed mouse cells. One result of interest is that in the 11A8 cell line about 40 per cent of the integrated SV40 DNA detectable by an RNA-DNA hybridization assay can be accounted for by a group of molecules which undergo complete strand separation within a 1.0 degree C interval.

Binding Sites↗
PubMed1972

Density heterogeneity of simian virus 40 ribonucleic acid late after infection of permissive cells.

Ribonucleic acid (RNA) was isolated from CV-1 cells 44 hr after simian virus 40 (SV40) infection. The molecules containing SV40 base sequences were characterized with respect to their buoyant density distribution. The density of these molecules was compared to that of single- and double-stranded RNA synthesized by using SV40 DNA and Escherichia coli RNA polymerase. The results suggest that about 20% of the SV40 RNA in the infected cells consisted of partially double-stranded molecules.

Animals↗