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Diane Schmidt

Publications and source records attributed to Diane Schmidt.

6 recordsLinked to original sources
PubMed2006

Variations of the melanocortin-1 receptor and the glutathione-S transferase T1 and M1 genes in cutaneous malignant melanoma.

Variations in the melanocortin-1 receptor (MC1R) and in the glutathione-S transferase genes mu1 (GSTM1) and theta 1 (GSTT1) have been reported to influence UV sensitivity and melanoma risk. MC1R is one of the major genes that determine skin pigmentation because the melanocortin-1 receptor regulates eumelanin synthesis. GSTT1 and GSTM1 are enzymes expressed in the skin that detoxify products of oxidative stress reactions caused by UV irradiation. In this study variations in the MC1R, GSTM1 and T1 genes were analyzed in 347 healthy subjects and 322 patients with cutaneous malignant melanoma by direct cycle sequencing, RFLP and multiplex PCR. Important phenotypic characteristics of the study participants were obtained to assess whether genetic associations occurred independently of phenotypic risk factors for melanoma. We found an association of the MC1R D84E and R151C polymorphisms with melanoma (odds ratios for carriage of the rare allele 4.96, 95% CI [1.06-23.13], P = 0.032, and 1.69, 95% CI [1.12-2.55], P = 0.013, respectively). Melanoma risk increased with the number of variant MC1R alleles carried by an individual (P = 0.003). In a multivariate model, however, only the D84E polymorphism influenced melanoma risk independently of the risk factors fair skin type, high nevus count and high age (P = 0.047). There was no effect of homozygous GST M1 or T1 deletions on melanoma risk. In contrast to previous data, there was no evidence that GSTM1 deficiency influences melanoma risk in the subgroup of individuals with red or blond hair.

Adult↗
PubMed2005

Multiparameter evaluation of human thymic function: interpretations and caveats.

After the provision of highly active antiretroviral therapy (HAART), the level of circulating CD4+ T cells increases in many adults infected with the human immunodeficiency virus, type 1 (HIV). To study factors involved in immune reconstitution, we have measured thymic abundance by CT scans, circulating naive-phenotype CD4+ T cells by flow cytometry, and T cell receptor (TCR) rearrangement excision circles (TRECs) by quantitative PCR in 40 virologically suppressed, HIV-infected adults and 33 age-matched, HIV-uninfected controls. In HIV-uninfected subjects, naive T cell numbers, thymic abundance, and the frequency of circulating naive CD4+ T cells bearing TRECs decreased with age, as expected. When corrected for this relationship with age, naive T cell numbers correlated significantly with naive T cell TREC frequencies. Virologically suppressed HIV-infected subjects had higher TREC frequencies, and subjects over the age of 39 were more likely to have abundant thymus compared to age-matched, HIV-uninfected adults. Nevertheless, all HIV-infected subjects had reduced absolute numbers of naive T cells, irrespective of thymic size, age, or TREC frequencies. These data illustrate the complex relationship between these measures of thymic size and function and underscore the need to develop more definitive measures of thymic function in the future.

Adult↗
PubMed2003

Brief communication: multiplex X/Y-PCR improves sex identification in aDNA analysis.

This study introduces a polymerase chain reaction (PCR)-based multiplex approach to improve the certainty of molecular sex identification on archaeological skeletal material. We coamplified amelogenin, two X-chromosomal short tandem repeats (STRs) (DXS6789 and DXS9898), and two Y-specific STRs (DYS391 and DYS392). The amplification results of this multiplex approach back each other up, and enable a reliable sex identification. This coamplification of X- and Y-specific markers in a multiplex assay combines the added advantage of positive identification of both female and male individuals with raising the validity of the diagnosis by obtaining multiple data simultaneously. This multiplex system was successfully applied to 3,000-year-old bone material.

Archaeology↗
PubMed2002

AB0 blood group genotyping of ancient DNA by PCR-RFLP.

The paper presents an PCR-RFLP-based method to determine AB0 blood groups at the genotype level. In order to ensure the applicability of the method to severely degraded DNA, new sets of primers were designed that amplify 103/104 bp and 64 bp sequences on exon 6 and exon 7 of chromosome 9, respectively. The amplification of the two PCR products and the subsequent RFLP analysis with four endonucleases was revealed to be an effective and reliable way to determine AB0 bloodgroups at the genotype level, distinguishing the alleles A, B, 0(1), 0(1v), and 0(2). PCR analysis of severely degraded sample material may possibly require higher cycle numbers. Therefore, the experiments presented here including those on positive control samples, were carried out employing 45 amplification cycles in order to ensure the validity of the amplification and RFLP analysis. As positive controls, small amounts of modern intact DNA extracted from saliva samples of 12 individuals with known AB0 phenotypes were used. The protocols for the AB0 typing were then applied to ancient degraded DNA extracted from 15 archaeological bones and teeth about 250 and 3,000 years old, respectively. The results presented for the archaeological sample material are based on repeated analysis derived from two independently processed DNA extracts of each sample. Moreover, the authentification process for the results derived from the archaeological samples included repeated multiplex STR genotyping of the extracts, showing the genetic uniqueness of the extracts which is the strongest possible indicator for the authenticity of an unknown DNA sample. Additionally, it was possible to compare the STR typing results to those from previous studies using the same material. Both the AB0 typing and the STR typing revealed fully reproducible results in all cases.

ABO Blood-Group System↗
PubMed2002

Increased thymic mass and circulating naive CD4 T cells in HIV-1-infected adults treated with growth hormone.

OBJECTIVE: To determine whether treatment with growth hormone (GH) enhances thymopoiesis in individuals infected with HIV-1. METHODS: Five HIV-1-infected adults were treated with GH for 6-12 months in a prospective open-label study. Immunological analyses were performed before GH treatment and repeated at 3 month intervals after GH initiation. Thymic mass was analysed using computed tomography with quantitative density and volume analysis. Analysis of circulating lymphocytes, including naive and memory T cell subsets, was performed using multiparameter flow cytometry. RESULTS: GH treatment was associated with a marked increase in thymic mass in all GH recipients. Circulating naive CD4 T cells also increased significantly in all patients during GH therapy, suggesting an enhancement of thymopoiesis. CONCLUSION: GH has significant effects on the human immune system, including the reversal of thymic atrophy in HIV-1-infected adults. De-novo T cell production may thus be inducible in immunodeficient adults.

Adult↗