Errors in diagnosis and margin determination of soft-tissue sarcomas initially treated at non-tertiary centers.

One hundred four patients with soft-tissue sarcoma referred to our institution who were initially managed at an outside medical center were retrospectively reviewed. The accuracy of histologic diagnosis and adequacy of tumor resection performed at these centers was evaluated. Review of the original pathologic specimens was performed. Thirty-seven percent of the histologic diagnoses were changed, and 82% of cases with excisional or wide resections had positive margins. The incidence of errors in diagnosis and inadequate tumor resection suggest that biopsy and histologic analysis of sarcomas should be performed by physicians experienced in their management.

Lentiviral genomes with G-to-A hypermutation may result from Taq polymerase errors during polymerase chain reaction.

Retroviral genomes with a high frequency of G-to-A mutations are thought to originate during reverse transcription. Here we show that bursts of G-to-A mutation may also occur during DNA synthesis by Taq polymerase on a simian immunodeficiency proviral template. These G-to-A changes tend to occur at GpA and, to a lesser extent, GpG dinucleotides. Because the resulting sequences are like previously reported hypermutant human and simian immunodeficiency virus (HIV and SIV) genomes, it is important to design experiments that can clearly discriminate between Taq and reverse transcripts errors in studies of lentiviral G-to-A hypermutation.

Nucleotide sequence of the splice junction of feline leukemia virus envelope mRNA.

The splice donor and acceptor sequences for the subgenomic envelope messenger RNA of feline leukemia virus (FeLV) were determined. The splice junction was characterized for viral mRNA from a prototype subgroup A FelV and an immunodeficiency-inducing FeLV variant. Thirty-seven of 38 partial envelope cDNAs, cloned after PCR amplification from T cells infected with either virus, utilized the same splice donor and acceptor sites to generate a mRNA that would be predicted to encode envelope protein. One novel cDNA, which could also code for envelope protein, was generated from a cryptic splice acceptor 109 nucleotides downstream of the normal junction. No additional subgenomic FeLV gene products were detected using reverse transcription and polymerase chain reaction amplification of FeLV sequences from chronically infected cells.

Replication and persistence of simian immunodeficiency virus variants after passage in macaque lymphocytes and established human cell lines.

In lentivirus infections, there are typically few cells in the host that harbor the provirus. For this reason, molecular clones of human and simian immunodeficiency viruses (HIV and SIV) are generally derived after passage and amplification of the virus in cell culture. To determine whether SIV variants that persist in culture are similar to the variants that predominate in the host, we examined the proviral sequence of the SIV envelope (env) gene before and after cocultivation of lymphocytes from a macaque with AIDS with naive macaque lymphocytes or human cell lines. Many of the predominant variants in the monkey replicated and persisted in macaque lymphocytes and CEMx174 cells in culture, but a more limited population of variants replicated in C8166 cells. Passage of virus, harvested after 4 weeks of coculture, onto naive cells further demonstrated that the majority of proviruses detected by polymerase chain reaction were also viral variants that were expressed and packaged into infectious virions.

Variation in simian immunodeficiency virus env is confined to V1 and V4 during progression to simian AIDS.

We have monitored changes in the simian immunodeficiency virus (SIV) envelope (env) gene in two macaques which developed AIDS after inoculation with a molecular clone of SIV. As the animals progressed to AIDS, selection occurred for viruses with variation in two discrete regions (V1 and V4) but not for viruses with changes in the region of SIV env that corresponds to the immunodominant, V3 loop of human immunodeficiency virus. Within the highly variable domains, the vast majority of nucleotide changes encoded an amino acid change (98%), suggesting that these envelope variants had evolved as a result of phenotypic selection. Analysis of the biological properties of these variants, which have been selected for in the host, may be useful in defining the mechanisms underlying viral persistence and progression to simian AIDS.