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Biomedical subjects

K Culver

Publications and source records attributed to K Culver.

15 recordsLinked to original sources
PubMed2004

High sensitivity scanning of colorectal tumors and matched plasma DNA for mutations in APC, TP53, K-RAS, and BRAF genes with a novel DHPLC fluorescence detection platform.

Tumor-associated DNA has been detected in plasma of colorectal cancer (CRC) patients using various techniques but with limited gene or mutation coverage. We report a highly sensitive scanning methodology for mutational assessment of the APC and TP53 genes, which typically pose an analytical challenge because of their significant genotypic heterogeneity as well as specific mutational scoring assays for K-RAS and BRAF. Plasma DNA isolated from 20 CRC patients were scanned for mutations in these targets without knowledge of the molecular or pathological analyses of the matched primary tumors. We chose mutation scanning technology and these molecular targets to provide a comprehensive screen for somatic mutations known to be associated with sporadic CRC. Mutations were identified with a novel denaturing high-performance liquid chromatography (DHPLC) platform that uses post-separation fluorescence technology to enable the detection of variants that represent <0.1% of the total analyzed DNA. Mutant allele specific amplification (MASA) followed by detection with the same platform was used to identify low-level target mutations (mutation scoring) in K-RAS codons 12, 13, and 61, and BRAF codon 599. Using this combined scanning and scoring approach, we were able to identify at least one mutational event in 20/20 (100%) CRC patients. The thoroughness of a mutation scanning and scoring panel may have important implications for CRC screening and disease monitoring during and following therapy.

Alleles↗
PubMed1991

Lymphocytes as cellular vehicles for gene therapy in mouse and man.

The application of bone marrow gene therapy has been stalled by the inability to achieve stable high-level gene transfer and expression in the totipotent stem cells. We show that retroviral vectors can stably introduce genes into antigen-specific murine and human T lymphocytes in culture. Murine helper T cells were transduced with the retroviral vector SAX to express both neomycin-resistance and human adenosine deaminase genes. These cells were expanded in culture and selected for expression of neomycin resistance with G418. The gene insertion, selection, and culture expansion did not alter antigen specificity or growth characteristics of the T cells in vitro. To determine if cultured T cells might be used for gene therapy, their persistence and continued expression of the introduced genes was evaluated in nude mice transplanted with the SAX-transduced T cells. G418-resistant cells could be readily recovered from the spleens of recipients of transduced T cells for several months. In addition, recovered cells continued to produce human adenosine deaminase. Based on these observations, we studied cultured human tumor-infiltrating lymphocytes as a candidate cell for a trial of gene transfer in man. Exponential cultures of interleukin-2-stimulated tumor-infiltrating lymphocytes were efficiently transduced with the neomycin-resistance gene using the retroviral vector N2. Gene insertion and subsequent G418 selection did not substantially alter the growth characteristics, interleukin 2 dependence, membrane phenotype, or cytotoxicity profile of the transduced T cells. These studies provided a portion of the experimental evidence supporting the feasibility of the presently ongoing clinical trials of lymphocyte gene therapy in cancer as well as in patients with adenosine deaminase deficiency.

Animals↗
PubMed1990

Human gene transfer: characterization of human tumor-infiltrating lymphocytes as vehicles for retroviral-mediated gene transfer in man.

Tumor-infiltrating lymphocytes (TILs) are cells generated from tumor suspensions cultured in interleukin 2 that can mediate cancer regression when adoptively transferred into mice or humans. Since TILs proliferate rapidly in vitro, recirculate, and preferentially localize at the tumor site in vivo, they provide an attractive model for delivery of exogenous genetic material into man. To determine whether efficient gene transfer into TILs is feasible, we transduced human TILs with the bacterial gene for neomycin-resistance (NeoR) using the retroviral vector N2. The transduced TIL populations were stable and polyclonal with respect to the intact NeoR gene integration and expressed high levels of neomycin phosphotransferase activity. The NeoR gene insertion did not alter the in vitro growth pattern and interleukin 2 dependence of the transduced TILs. Analyses of T-cell receptor gene rearrangement for beta- and gamma-chain genes revealed the oligoclonal nature of the TIL populations with no major change in the DNA rearrangement patterns or the levels of mRNA expression of the beta and gamma chains following transduction and selection of TILs in the neomycin analog G418. Human TILs expressed mRNA for tumor necrosis factors (alpha and beta) and interleukin 2 receptor P55 but not for interleukin 1 beta, granulocyte/macrophage colony-stimulating factor, interleukin 6, and interferon gamma when grown with high-dose interleukin 2 without subsequent activation with mitogen or specific antigen. This pattern of cytokine-mRNA expression was not significantly altered following the transduction of TILs. The NeoR gene-transduced TILs could thus be used to follow the trafficking and survival of TILs in vivo, and clinical protocols using these transduced TILs in cancer patients have begun. The studies demonstrate the feasibility of TILs as suitable cellular vehicles for the introduction of therapeutic genes into patients receiving autologous TILs.

Biological Factors↗
PubMed1990

Amphotropic murine leukemia retrovirus is not an acute pathogen for primates.

The in vivo fate of amphotropic murine leukemia retrovirus was studied in five rhesus monkeys. Retrovirus infused intravenously into 3 normal animals and 1 immunosuppressed animal was cleared rapidly from the circulation and subsequent viremia has not been detected (mean follow-up of 27.4 months). A fifth monkey was immunosuppressed and transplanted with virus-producing autologous fibroblasts in addition to an intraperitoneal injection of virus. This animal was viremic for 2 days and its lymph node cells and peripheral blood mononuclear cells were shown to be producing virus for up to 22 days post-inoculation, but subsequently has been negative after 17.0 months of analysis. In the 5 animals studied (combined mean follow-up of 25.7 months), clinical illness has not been identified at any time. Therefore, murine amphotropic retroviruses do not appear to pose an acute health risk.

AIDS-Related Complex↗
PubMed1988

Maternally transmitted HIV infection in children.

We evaluated 16 children at high risk for AIDS because of mothers infected with HIV. Two children were persistently seropositive and had laboratory and clinical evidence of HIV infection but had no detectable infectious HIV in their peripheral blood mononuclear cells (PBMC). Seven children, all of whom had clinical and laboratory evidence of HIV infection, were seropositive and virus culture-positive. One child who died at 10 months of age of candida septicemia was HIV antibody-negative but HIV was grown from cultures of his PBMC. Six children had no serologic or virologic evidence of HIV infection; of these, four who were asymptomatic with normal laboratory studies were HIV antibody-positive up to 12 months of age but became antibody-negative by 15 months of age. These observations indicate that: (1) as many as 60% of infants of infected mothers may be infected with HIV; (2) maternal antibody can result in a false-positive or false-negative diagnosis of HIV infection in infants exposed in utero or perinatally, and (3) the use of viral cultures for HIV is valuable for the early diagnosis of maternally transmitted HIV infection.

Acquired Immunodeficiency Syndrome↗
PubMedDate not supplied

Role of dopamine systems in obsessive-compulsive disorder (OCD): implications from a novel psychostimulant-induced animal model.

OCD was once considered a rare psychiatric disorder, but recent studies estimate that, in the general population, the lifetime prevalence of OCD is 1 to 2%, twice that of schizophrenia or panic disorder. The most common form of OCD is compulsive checking. Our studies show that the behavior of rats treated chronically with the dopamine agonist, quinpirole, meets the ethological criteria of compulsive checking in OCD; may have a similar motivational basis as compulsive checking in the human; and is partially attenuated by the anti-OCD drug, clomipramine. Thus, the behavioral changes induced by chronic treatment with quinpirole may constitute an animal model of OCD checking. Since behavioral sensitization is an associated effect of quinpirole treatment, the induction of compulsive checking by quinpirole may involve the same mechanisms as the induction of drug-induced sensitization. In this respect, we demonstrated that the MAO inhibitor clorgyline, not only prevented the development of locomotor sensitization to quinpirole, but also reversed it in sensitized rats. To the extent that the quinpirole treatment is an animal model of OCD with strong face validity, it strengthens the hypothesis that dopamine systems play a role in OCD and raises the possibility that MAO inhibitors, which are used clinically for OCD, may exert their effects by acting at the MAO inhibitor displaceable quinpirole binding site.

Animals↗