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Biomedical subjects

R H Jensen

Publications and source records attributed to R H Jensen.

At least 55 records · Page 3Linked to original sources
PubMed1994

Comparative genomic hybridization, allelic imbalance, and fluorescence in situ hybridization on chromosome 8 in prostate cancer.

Due to problems with primary tumor cell culture, conventional cytogenetics has yielded little insightful information on chromosomal alterations in prostate cancer. The primary aim of this study was to define the ability of comparative genomic hybridization (CGH) to detect and map genetic deletions in prostate tumors. A secondary aim was to apply multiple assays to individual tumors as a means of deciphering the mechanisms of genetic alterations in prostate cancer. CGH results were compared with allelic imbalance measurements at 29 distinct loci on chromosome 8 in 18 specimens (17 malignant and 1 benign). CGH detected no changes in cases where all informative PCR/RFLP loci were retained and detected all p arm deletions consisting of at least two loci. We estimate that in this study, the smallest deletions detected by CGH were approximately 20-30 cM. Physical mapping of subchromosomal arm deletions by CGH correlated well with allelic imbalance mapping by PCR/RFLP: The data agreed at 88% of loci on 8p and 92% of loci on 8q. Fluorescence in situ hybridization (FISH) with multiple centromere probes and DNA content flow cytometry (FCM) also was performed on selected specimens. FISH revealed two cases of chromosome 8 aneusomy. In these two cases and three others, CGH showed simultaneous p arm deletion and q arm gain, suggesting isochromosome 8q formation. Together, these data suggested that, simple chromosomal aberrations were responsible for allelic losses on 8p and allelic gains on 8q in a significant number of prostate tumors. We also used CGH to examine relative DNA sequence copy number throughout the genome. Changes frequently associated with 8p loss include gains of 8q and losses of 13q, 16p, 16q, 17p, 17q, 20q, and Y. Cases with 8p loss exhibited five times the number of alterations as did cases without 8p loss.

Alleles↗
PubMed1994

Renal cell carcinoma: prognostic factors.

OBJECTIVE: To establish the prognostic value of a series of pre-operative, per-operative and histopathological parameters in relation to renal cell carcinoma (RCC). PATIENTS AND METHODS: This retrospective study involved a consecutive series of 76 patients (46 men and 30 women with a mean age of 65.3 years [range 44-91]) with a histologically confirmed diagnosis of RCC. Patients who were admitted over the period 1980-1984 were included. Data such as erythrocyte sedimentation rate (ESR), alkaline phosphatase level, histological tumour grade, degree of necrosis and presence of tumour vessels were evaluated in relation to actuarial survival. RESULTS: The ESR and alkaline phosphatase level at the time of diagnosis of RCC, the histological tumour grade, degree of necrosis and presence of tumour vessels on angiography were all found to affect the actuarial length of survival significantly (P < or = 0.05 log-rank test). Macroscopic tumour demarcation estimated per-operatively by the surgeon or after surgery by the pathologist, microscopic demarcation, vascular density on histological examination, tumour diameter and vascular density on angiography were found not to affect actuarial survival significantly. CONCLUSION: The value of establishing simple and reliable diagnostic indicators for patients with RCC is stressed.

Adult↗
PubMed1993

Electroacupuncture in anaesthesia for hysterectomy.

We have studied the effects of electroacupuncture at classical acupuncture points, applied before and during surgery in patients undergoing hysterectomy, on postoperative pain and metabolic stress responses in a prospective, randomized and patient-blinded manner. Fifty otherwise healthy women were allocated randomly to receive or not receive electroacupuncture. Electroacupuncture was begun 20 min before skin incision and continued to the end of surgery. All patients received similar general anaesthesia and all received patient-controlled analgesia (PCA) after operation. Postoperative pain in the two groups was evaluated by recording analgesic requirements by PCA and by pain-rating performed by patients and nursing staff. There were no significant differences between the two groups in postoperative analgesic requirements, pain-rating or metabolic stress responses.

Adult↗
PubMed1993

Use of the glycophorin A human mutation assay to study workers exposed to styrene.

The glycophorin A (GPA) assay is a human mutation assay that is potentially useful for large epidemiological studies. The assay is rapid and requires a minimal amount of blood, which can be stored before analysis. The data presented here were collected from workers exposed to styrene in a boat manufacturing plant. This study was the first to apply the GPA assay to an occupationally exposed population. Subjects with a mean styrene exposure of 30 ppm had a higher frequency of GPA N phi variant cells than subjects with mean exposure of 1 ppm, but the subjects differed in respect to smoking and age distribution. Results indicate that the original 1-W-1 version of the assay may not be suitable for studies of small numbers of exposed subjects due to variability and artifacts. The newer BR6 version, however, has much lower variability and shows promise for use in the occupational setting.

Evaluation Studies as Topic↗
PubMed1993

Analysis of somatic cell mutations at the glycophorin A locus in atomic bomb survivors: a comparative study of assay methods.

The glycophorin A (GPA) assay for in vivo somatic cell mutations was performed on blood samples from 39 survivors of the atomic bomb at Hiroshima. Parallel analyses were performed at two laboratories using three different GPA assay methods to enumerate cells lacking expression of either the M- or N-allele of GPA. All assay methods yielded significant dose-dependent increases in hemizygous GPA variant cell frequencies (VFs) and smaller increases in homozygous VFs. The slopes of the fitted linear dose-response functions did not differ significantly among assay methods used in the present study, or from slopes obtained in a study reported previously. The version of the assay described most recently (BR6) appears best suited for future studies because the assay has a higher precision than earlier methods. Variant frequencies from different assay methods measuring the same variant cell type agreed with each other better than with the estimated dose, suggesting that the imprecision in the assay is not primarily responsible for VFs that differ from the fitted dose response. Consistent deviations from the dose response were seen for some individuals, suggesting either errors in dose estimates for these individuals or interindividual differences in susceptibility or other exposures. For the study population as a whole, however, discrepancies between assays for M-loss and N-loss variants suggest stochastic factors may have an important effect on individual VFs for A-bomb survivors.

Chromosome Mapping↗
PubMed1992

Multiple biological markers in germ cell tumor patients treated with platinum-based chemotherapy.

Blood samples from 36 germ cell tumor patients receiving chemotherapy with either cisplatin or carboplatin in combination with other drugs [etoposide or vinblastine, cyclophosphamide, dactinomycin, and bleomycin (VAB-6)] were analyzed for the presence of 7 different biological markers. The biomarkers included platinum-protein adducts, platinum-DNA adducts, sister chromatid exchange (SCE), micronuclei (MN), and somatic gene mutation at the hypoxanthine phosphoribosyl transferase (HPRT) locus and the glycophorin A (GPA) loci (NO and NN). Patients were asked to donate 9 serial blood samples: a pretreatment sample followed by another drawn 12-24 h after each of four cycles of treatment and a final sample provided 3-6 months after the last cycle. Most individuals gave 7-8 samples; 7 individuals donated all 9. Because of limited amounts of cells in some cases, it was not possible to carry out all 7 assays on every sample. Pt-protein adducts, Pt-DNA adducts, and SCE showed a direct and consistent effect of treatment and were very highly correlated. A significant correlation was also seen between both Pt-protein and Pt-DNA adducts and HPRT mutation. All of the posttreatment samples were significantly elevated compared to the baseline sample. These markers also remained elevated 3-6 months after the end of treatment. By contrast, MN, HPRT mutation, and GPA mutation (both NO and NN variants) showed varying patterns of dose response, probably reflective of the differing biology of these markers scored in lymphocytes (MN and HPRT) and erythrocytes (GPA). MN were significantly elevated in the posttreatment samples drawn at cycles 2 and 3. Although induction of HPRT mutation was only of marginal significance, results here are for the mutant frequency determination assay only. In progress is the potentially more informative analysis of the type of mutations by Southern blot and the sequencing of mutations to look for characteristic mutational spectra. The GPA assay showed a significant increase over baseline in samples drawn after cycles 3 and 4 (NO variants) and after cycles 2, 3, and 4 (NN variants). The level of GPA mutation (both NO and NN variants) was clearly elevated even 3-6 months after the last cycle of chemotherapy. Correlations were seen between HPRT and MN as well as between GPA NO and GPA NN variants. Analysis of biomarkers by treatment group does not reveal a consistent pattern or trend across all cycles.(ABSTRACT TRUNCATED AT 400 WORDS)

Adolescent↗
PubMed1991

Novel biodosimetry methods applied to victims of the Goiânia accident.

Two biodosimetric methods under development at the Lawrence Livermore National Laboratory were applied to five persons accidentally exposed to a 137Cs source in Goiânia, Brazil. The methods used were somatic "null" mutations at the glycophorin A locus detected as missing proteins on the surface of blood erythrocytes and chromosome translocations in blood lymphocytes detected using fluorescence in-situ hybridization. Biodosimetric results obtained approximately 1 y after the accident using these new and largely unvalidated methods are in general agreement with results obtained immediately after the accident using dicentric chromosome aberrations. Additional follow-up of Goiânia accident victims will 1) help provide the information needed to validate these new methods for use in biodosimetry and 2) provide independent estimates of dose.

Accidents↗
PubMed1990

Flow cytometric analysis of erythrocyte populations in Tn syndrome blood using monoclonal antibodies to glycophorin A and the Tn antigen.

Flow cytometric analysis employing monoclonal antibodies to the Tn antigen and glycophorin A was used to characterize the erythrocyte populations present in blood samples from individuals with Tn syndrome. Four monoclonal antibodies specific for the Tn antigen, Gal-NAc monosaccharide, on human erythrocytes were obtained from a fusion of splenocytes from a Biozzi mouse immunized with red cells from a Tn individual. These monoclonal antibodies specifically recognize GalNAc monosaccharide sites located on the erythrocyte cell surface sialoglycoproteins, glycophorin A and glycophorin B, and do not bind to fixed normal red cells presenting the Neu-NAc alpha 2-3Gal beta 1-3(NeuNAc alpha 2-6)GalNAc alpha 1-O-Ser(Thr) tetrasaccharide or to fixed neuraminidase-digested cells presenting the Gal-GalNAc disaccharide. The percentages of Tn-positive red cells in samples from six unrelated Tn donors ranged from 28 to 99%. Binding of the glycophorin A-specific monoclonal antibodies showed that the erythrocytes composing the Tn-negative fraction presented normal amounts of the M and N epitopes on glycophorin A. The presumed somatic mutational origin of Tn-positive cells was tested in blood samples from five normal donors; three possible Tn cells were observed after analysis of a total of 1.1 x 10(7) erythrocytes, suggesting that the frequency of such cells in normal individuals is less than 1 x 10(-6).

Antibodies, Monoclonal↗
PubMed1990

An improved flow cytometric assay for somatic mutations at the glycophorin A locus in humans.

An improved method has been developed for the glycophorin A assay for somatic cell mutations in humans. The new assay, named the "BR6" assay, can be performed on a commercially available, single-beam flow cytometer, in contrast to the previously described 1W1 assay that required a dual-beam flow sorter. A modified cell labeling method developed for the BR6 assay results in improved separation of normal and mutant phenotype cells, as well as eliminating some cellular artifacts that affected the 1W1 assay. Parallel measurements on samples from 17 normal donors showed that the BR6 assay yields comparable variant cell frequencies and improved measurement precision compared with the 1W1 assay. A detailed analysis of three individuals who showed large differences in background variant frequency with the 1W1 assay confirmed that these differences could also be detected with the BR6 assay. A dramatically elevated variant cell frequency was seen with the BR6 assay of an individual exposed to a high level of ionizing radiation in an accident at Goiania, Brazil.

Adult↗
PubMed1990

The effect of chemotherapy on the in vivo frequency of glycophorin A 'null' variant erythrocytes.

A human in vivo somatic cell assay based on the enumeration of variant erythrocytes lacking expression of an allelic form of the cell-surface sialoglycoprotein, glycophorin A, was applied to the study of blood samples from patients obtained prior to, during, and following chemotherapy for malignant disease in order to determine the effect of mutagenic chemical agents on the frequency of variant cells. In 22 patients assayed prior to therapy, the mean variant cell frequency was 11.9 per million, which was not significantly different from that observed in healthy controls. In an initial cross-sectional survey, blood samples were obtained at various times during and after therapy from 30 patients diagnosed with a variety of malignancies who were treated with one or more known mutagenic agents including adriamycin, bleomycin, cis-platinum, cyclophosphamide, dacarbazine, etoposide, lomustine, mechlorethamine, melphalan, mitomycin C, and procarbazine. Significant elevations in the mean frequency of variant cells over pre-therapy and normal levels were observed in samples obtained during and after therapy. In a time-series study, 14 breast cancer patients treated with CAF (cyclophosphamide, adriamycin, 5-fluorouracil), CMF (cyclophosphamide, methotrexate, 5-fluorouracil), or VMF (vinblastine, methotrexate, 5-fluorouracil) adjuvant chemotherapy were sampled repeatedly during and after therapy. For the CAF and CMF patients an increase in the frequency of variant cells was observed with a lag in the appearance of induced variants after initiation of therapy; variant frequencies gradually increased during therapy reaching a maximum at or shortly after the end of therapy, then declined to near pre-therapy levels within 6 months. The maximum level of induced variants ranged from 2- to 7-fold over pre-therapy or normal levels depending on the combination of agents used. The breast cancer patients treated with both adriamycin and cyclophosphamide showed consistent elevations in the frequency of variant cells; patients treated only with cyclophosphamide showed lower and more variable elevations. The data demonstrate that mutagenic chemotherapy agents induce elevated levels of glycophorin A variant erythrocytes consistent with the hypothesis that variant cells result from somatic mutation. The elevations in variant cells were transient, suggesting that these agents primarily affect the rapidly cycling committed erythroid cell population.

Adolescent↗
PubMed1990

Antibiotic prophylaxis in transurethral surgery. Ceftriaxone versus cephradine versus control. A randomized, prospective study in low risk patients.

In this prospective, randomized study, the efficacy of one dose ceftriaxone or 48 hour cephradine therapy was compared to a control group to prevent urinary infection in 179 patients undergoing TUS. Only patients with low risk of developing infections were included. Both cephalosporins significantly reduced the incidence of UTI (ceftriaxone 11.9%, cephradine 17.6% compared to controls 47.2%; p less than 0.0005). Ceftriaxone seemed to have the definite edge in antibacterial spectrum and was easier to administer. Both regimens were well tolerated. Culture of prostatic chips did not have any significant predictive value to determine which patients would develop UTI.

Aged↗
PubMed1990

Multiple endpoints for somatic mutations in humans provide complementary views for biodosimetry, genotoxicity and health risks.

While monitoring people with multi-endpoint analysis is only just beginning, the indications of complementarity of these assays are already evident. Since two different tissue types are analyzed, effects of uneven exposure or tissue-specific sensitivities or development kinetics and persistence of each cell type can be addressed. The differing analytical techniques in determining variant cells lead to particular advantages for each assay procedure. The GPA assay can be performed rather quickly on small blood volumes (as little as 0.1 ml). A similar potential exists for the Hb assay, although sophisticated instrumentation development is still required to make this assay easily performable. Both the HPRT and HLA assays require long term tissue growth and many-fold larger (10-30 ml) blood samples. However, both the HPRT and HLA assays have the advantage that they select variant cells that contain nuclei, so that detailed characterization of their mutagenesis is possible using Southern blots, hybridization analysis, and gene sequencing. Since erythrocytes have no nucleic acids, so these effects cannot be measured using the GPA or Hb assay. Other differences between the assays are the target size, chromosomal location, and control signals. Each gene locus is on a different chromosome, with GPA, HLA and Hb genes on autosomes and HPRT on the X chromosome. The target size for GPA and HPRT are about 40kb, whereas HLA A locus is 5kb and the Hb target is one base. These differences should result in much different sensitivity to different mutagenic phenomena, such as radiation effects or different chemical effects. The multiple differences between assays that are designed to detect similar kinds of events occurring in vivo in humans leads us to conclude that all these assays could well be performed on the same blood samples, and the information gained would be much more than the separate assays could yield. Biodosimetry and estimation of cancer initiation could become realistic goals instead of simply significant desires.

Aging↗
PubMed1989

Detection of somatic mutations at the glycophorin A locus in erythrocytes of atomic bomb survivors using a single beam flow sorter.

A modified method was developed for measuring the frequency of variant erythrocytes at the glycophorin A locus using a single beam cell sorter (SBS). Fluorescein- or phycoerythrin-labeled monoclonal antibodies specific for the M or N glycophorin A alleles were used for the SBS assay. To prevent contamination of nucleated cells in the sorting windows, the nucleated cells in the fixed erythrocyte sample were stained with propidium iodide before flow sorting. Blood samples were obtained from atomic bomb survivors who were heterozygous for the MN blood type, and the frequencies of the hemizygous and homozygous variant of the M or N glycophorin A allele were measured by the SBS. For the three types of variants, hemizygotes for M and N allele (Nø and Mø) and homozygotes for M allele (MM), the variant frequency measured by the SBS correlated well with that previously determined by a dual beam cell sorter. Variant frequencies of the Nø, Mø, and MM cell types in atomic bomb survivors determined by SBS measurements were found to increase with radiation dose (DS86, kerma) as well as with the frequency of chromosome aberrations in lymphocytes.

Alleles↗
PubMed1989

Evidence for increased in vivo mutation and somatic recombination in Bloom's syndrome.

The glycophorin A assay was used to estimate the frequency of mutations that accumulate in vivo in somatic cells of persons with Bloom's syndrome (BS). This assay measures the frequency in persons of blood type MN of variant erythrocytes that lack the expression of one allelic form of glycophorin A, presumably due to mutational or recombinational events in erythroid precursor cells. Samples of blood from persons with BS showed dramatic 50- to 100-fold increases in the frequency of variants of three types, those with a hemizygous phenotype, those with a homozygous phenotype, and those with what appears to be partial loss of the expression of one locus. The high frequency of homozygous variants, genetic evidence for altered allelic segregation of a specific biochemical locus, provides evidence for increased somatic crossing-over in vivo in BS. An increased generation of functional hemizygosity and homozygosity in their somatic cells may play an important role in the extreme cancer risk of persons with BS.

Adolescent↗
PubMed1989

Evidence for an elevated frequency of in vivo somatic cell mutations in ataxia telangiectasia.

Somatic cell mutation frequency in vivo was measured in individuals with high cancer risk who were from ataxia telangiectasia (A-T) families. The assay for somatic mutation measures the frequency of variant erythrocytes which are progeny of erythroid precursor cells with mutations that result in a loss of gene expression at the polymorphic glycophorin A (GPA) locus. Samples from 14 of 15 A-T homozygotes showed high frequencies of GPA gene expression-loss variant cells with normal expression of only one of the two alleles at the GPA locus (i.e., GPA hemizygous variant cells). The mean elevation of the frequency of hemizygous variant cells over those in normal controls and unaffected family members was 7-14-fold. A-T homozygotes also showed an increase in the frequency of cells in which one allele at the GPA locus had lost expression and in which the remaining allele was expressed at a homozygous level (i.e., GPA homozygous variant cells). Family members who are obligate A-T heterozygotes did not appear to have a significantly elevated frequency of GPA hemizygous or homozygous variant cells. These indications of elevated in vivo frequencies of variant erythrocytes in A-T homozygotes support a causal link between susceptibility to somatic mutation and susceptibility to cancer.

Adult↗