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Biomedical subjects

J Stenman

Publications and source records attributed to J Stenman.

8 recordsLinked to original sources
PubMed2003

Quantitative detection of low-copy-number mRNAs differing at single nucleotide positions.

Accurate analysis of mRNA expression levels of SNPs, highly homologous genes, and splicing variants requires techniques capable of quantifying low-copy-number mRNAs differing at single nucleotide positions. We have used an RT-PCR-based technique based on co-amplification of closely related target mRNA transcripts and assessed the effect of the stochastic distribution of low-copy-number templates on sampling variation when quantifying rare mRNA transcripts. The technique was optimized for maximal sensitivity to enable the analysis of samples containing a subpopulation of target cells and small microdissected samples. We demonstrate that the input level of template molecules is a critical determinant of the achievable assay precision. A minimum of approximately 50 molecules of template is required to discriminate between 2-fold differences in the expression levels of two transcripts. At levels above 1000 molecules of input template, the stochastic effects on sampling variation become negligible.

Antigens, Neoplasm↗
PubMed2001

Relative levels of SCCA2 and SCCA1 mRNA in primary tumors predicts recurrent disease in squamous cell cancer of the head and neck.

Squamous cell carcinoma antigen (SCCA) is widely used as a serum marker in cancers of the uterine cervix, the head and neck, lung and esophagus. Two isoforms of SCCA, deriving from 2 highly homologous serine proteinase inhibitor genes, are co-expressed in normal and malignant squamous epithelium, but it is mainly the acidic isoform SCCA2 that is present in the circulation of cancer patients. We studied the relative levels of SCCA2 and SCCA1 mRNA in frozen sections of squamous cell carcinomas of the head and neck (SCCHN) in relation to disease recurrence, using a new reverse transcription-polymerase chain reaction-based technique for accurate quantitation of relative mRNA levels. Primary tumors from 30 SCCHN patients, recurrent tumors from 11 patients and normal epithelium from 16 controls were examined. In patients responding to initial therapy (n = 26), an elevated SCCA2/SCCA1 mRNA ratio in the primary tumor predicted recurrence independent of clinical stage (p = 0.011). The relative risk of developing a recurrence was 7.2 (CI 1.2-13.3) in patients with elevated vs. normal SCCA2/SCCA1 mRNA ratios. We demonstrate that subtle differences in expression levels of the SCCA genes are reflected in the course of the SCCHN disease and may provide a target for molecular grading of SCCHN tumors. If this finding can be confirmed in a larger study the SCCA2/SCCA1 mRNA ratio in primary tumors could be useful for individual selection of treatment strategy for patients with head and neck cancer.

Adult↗
PubMed1999

Detection of messenger RNA for the beta-subunit of chorionic gonadotropin in urinary cells from patients with transitional cell carcinoma of the bladder by reverse transcription-polymerase chain reaction.

We studied whether detection of messenger-RNA (mRNA) for the beta-subunit of chorionic gonadotropin (CGbeta) in urinary cells from bladder cancer patients could be used as a marker of disease activity. Sixty-eight urine samples from patients under follow-up for bladder cancer and 23 samples from patients with other malignancies and non-malignant surgical conditions, as well as 14 samples from healthy controls were analyzed. RNA was isolated from urinary cells collected by centrifugation. Reverse transcription-polymerase chain reaction (RT-PCR) was used to detect CGbeta mRNA. The results were compared to those obtained by cystoscopy and urinary cytology. For comparison, we determined CG and CGbeta in serum and urine and the core fragment of CGbeta (CGbeta cf) in urine by immunofluorometric assays. CGbeta mRNA was detected in 29 of 68 urine samples from patients with a history of bladder cancer, whereas all 14 samples from healthy controls tested negative. Elevated levels of CGbeta were observed in serum in 18 of 45 bladder cancer patients, but the association with CGbeta mRNA was weak. However, CGbeta mRNA expression in the absence of detectable cancer also occurred in some conditions associated with cellular atypia such as urinary tract infection, instrumentation and certain therapies. There was a highly significant association between histologically verified transitional cell carcinoma of the bladder and CGbeta mRNA in urine (p = 0.0014), implying CGbeta mRNA expression in tumor tissue. We conclude that CGbeta mRNA is a potential new marker for monitoring of bladder cancer. Further studies are needed to evaluate whether it provides independent clinical information.

Carcinoma, Transitional Cell↗
PubMed1997

Detection of squamous-cell carcinoma antigen-expressing tumour cells in blood by reverse transcriptase-polymerase chain reaction in cancer of the uterine cervix.

We used a reverse transcriptase-polymerase chain reaction method for squamous-cell carcinoma (SCC) antigen mRNA to detect circulating tumour cells in patients with carcinoma of the uterine cervix. The sensitivity of the method, as determined by cell spiking experiments, was 10 cultured A431 cells among 10(6) white blood cells. Circulating tumour cells were detected in 6 of 15 patients. In our control group of 24 women, SCC antigen mRNA was detected in 2 pregnant women at term. We followed up the patients for 24 months after sampling and evaluated the outcome. Three out of 6 patients positive for SCC antigen mRNA have relapsed. Additionally, 1 patient has developed breast cancer. In the group of 9 patients negative for SCC antigen mRNA there has been 1 relapse and 1 case of progression of disease. These results suggest that detection of SCC antigen mRNA in peripheral blood by RT-PCR could be useful for staging and evaluation of prognosis in epidermoid carcinoma of the uterine cervix.

Antigens, Neoplasm↗
PubMed1994

Streptavidin-biotin based time-resolved immunofluorometric assay for direct measurement of high concentrations of human chorionic gonadotropin (hCG).

Quantitation of human chorionic gonadotropin (hCG) in maternal serum is widely used for screening of fetal trisomy-21 (Down's syndrome). When using immunometric assay, the sample usually has to be prediluted in order to quantitate the high hCG concentrations occurring during weeks 10-17 of pregnancy. Utilizing a streptavidin-biotin system we have developed an immunofluorometric assay (IFMA) for the quantitation of hCG in pregnancy serum that does not require predilution of the sample. The sample is added to a streptavidin coated microtiter strip well together with a biotinylated 'capture' antibody. About 1-2% of the capture antibody is biotinylated whereas most of the antibodies are unbiotinylated and thus unable to bind to the solid phase, while still binding antigen. This displaces the assay range from 0.5-5000 IU/l of the standard assay to 20-250,000 IU/l. The method shows good correlation with the standard procedure (r = 0.96). By eliminating a dilution step the assay procedure is both simplified and reinforced. The principle of this method should be readily applicable to other antigens and detection methods.

Bacterial Proteins↗