RENEB Inter-Laboratory Comparison 2021: Inter-Assay Comparison of Eight Dosimetry Assays

Tools for radiation exposure reconstruction are required to support the medical management of radiation victims in radiological or nuclear incidents. Different biological and physical dosimetry assays can be used for various exposure scenarios to estimate the dose of ionizing radiation a person has absorbed. Regular validation of the techniques through inter-laboratory comparisons (ILC) is essential to guarantee high quality results. In the current RENEB inter-laboratory comparison, the performance quality of established cytogenetic assays [dicentric chromosome assay (DCA), cytokinesis-block micronucleus assay (CBMN), stable chromosomal translocation assay (FISH) and premature chromosome condensation assay (PCC)] was tested in comparison to molecular biological assays [gamma-H2AX foci (gH2AX), gene expression (GE)] and physical dosimetry-based assays [electron paramagnetic resonance (EPR), optically or thermally stimulated luminescence (LUM)]. Three blinded coded samples (e.g., blood, enamel or mobiles) were exposed to 0, 1.2 or 3.5 Gy X-ray reference doses (240 kVp, 1 Gy/min). These doses roughly correspond to clinically relevant groups of unexposed to low exposed (0-1 Gy), moderately exposed (1-2 Gy, no severe acute health effects expected) and highly exposed individuals (>2 Gy, requiring early intensive medical care). In the frame of the current RENEB inter-laboratory comparison, samples were sent to 86 specialized teams in 46 organizations from 27 nations for dose estimation and identification of three clinically relevant groups. The time for sending early crude reports and more precise reports was documented for each laboratory and assay where possible. The quality of dose estimates was analyzed with three different levels of granularity, 1. by calculating the frequency of correctly reported clinically relevant dose categories, 2. by determining the number of dose estimates within the uncertainty intervals recommended for triage dosimetry (±0.5 Gy or ±1.0 Gy for doses <2.5 Gy or >2.5 Gy), and 3. by calculating the absolute difference (AD) of estimated doses relative to the reference doses. In total, 554 dose estimates were submitted within the 6-week period given before the exercise was closed. For samples processed with the highest priority, earliest dose estimates/categories were reported within 5-10 h of receipt for GE, gH2AX, LUM, EPR, 2-3 days for DCA, CBMN and within 6-7 days for the FISH assay. For the unirradiated control sample, the categorization in the correct clinically relevant group (0-1 Gy) as well as the allocation to the triage uncertainty interval was, with the exception of a few outliers, successfully performed for all assays. For the 3.5 Gy sample the percentage of correct classifications to the clinically relevant group (≥2 Gy) was between 89-100% for all assays, with the exception of gH2AX. For the 1.2 Gy sample, an exact allocation to the clinically relevant group was more difficult and 0-50% or 0-48% of the estimates were wrongly classified into the lowest or highest dose categories, respectively. For the irradiated samples, the correct allocation to the triage uncertainty intervals varied considerably between assays for the 1.2 Gy (29-76%) and 3.5 Gy (17-100%) samples. While a systematic shift towards higher doses was observed for the cytogenetic-based assays, extreme outliers exceeding the reference doses 2-6 fold were observed for EPR, FISH and GE assays. These outliers were related to a particular material examined (tooth enamel for EPR assay, reported as kerma in enamel, but when converted into the proper quantity, i.e. to kerma in air, expected dose estimates could be recalculated in most cases), the level of experience of the teams (FISH) and methodological uncertainties (GE). This was the first RENEB ILC where everything, from blood sampling to irradiation and shipment of the samples, was organized and realized at the same institution, for several biological and physical retrospective dosimetry assays. Almost all assays appeared comparably applicable for the identification of unexposed and highly exposed individuals and the allocation of medical relevant groups, with the latter requiring medical support for the acute radiation scenario simulated in this exercise. However, extreme outliers or a systematic shift of dose estimates have been observed for some assays. Possible reasons will be discussed in the assay specific papers of this special issue. In summary, this ILC clearly demonstrates the need to conduct regular exercises to identify research needs, but also to identify technical problems and to optimize the design of future ILCs.

RENEB Inter-Laboratory Comparison 2021: The FISH-Based Translocation Assay

Translocation analysis using fluorescence in situ hybridization (FISH) is the method of choice for dose assessment in case of chronic or past exposures to ionizing radiation. Although it is a widespread technique, unlike dicentrics, the number of FISH-based inter-laboratory comparisons is small. For this reason, although the current Running the European Network of Biological and Physical retrospective Dosimetry (RENEB) inter-laboratory comparison 2021 was designed as a fast response to a real emergency scenario, it was considered a good opportunity to perform an inter-laboratory comparison using the FISH technique to gain further experience. The Bundeswehr Institute of Radiobiology provided peripheral blood samples from one healthy human volunteer. Three test samples were irradiated with blinded doses of 0, 1.2, and 3.5 Gy, respectively. Samples were then sent to the seven participating laboratories. The FISH technique was applied according to the standard procedure of each laboratory. Both, the frequency of translocations and the estimated dose for each sample were sent to the coordinator using a special scoring sheet for FISH. All participants sent their results in due time. However, although it was initially requested to send the results based on the full analysis, evaluating 500 equivalent cells, most laboratories only sent the results based on triage, with a smaller number of analyzed cells. In the triage analysis, there was great heterogeneity in the number of equivalent cells scored. On the contrary, for the full analysis, this number was more homogeneous. For all three samples, one laboratory showed outlier yields compared to the other laboratories. Excluding these results, in the triage analysis, the frequency of translocations in sample no. 1 ranged from 0 to 0.013 translocations per cell, and for samples no. 2 and no. 3 the genomic mean frequency were 0.27 ± 0.03 and 1.47 ± 0.14, with a coefficient of variation of 0.29 and 0.23 respectively. Considering only results obtained in the triage analysis for sample no. 1, all laboratories, except one, classified this sample as the non-irradiated one. For sample no. 2, excluding the outlier value, the mean reported dose was 1.74 ± 0.16 Gy indicating a mean deviation of about 0.5 Gy to the delivered dose of 1.2 Gy. For sample no. 3 the mean dose estimated was 4.21 ± 0.21 Gy indicating a mean deviation of about 0.7 Gy to the delivered dose of 3.5 Gy. In the frame of RENEB, this is the second FISH-based inter-laboratory comparison. The whole exercise was planned as a response to an emergency, therefore, a triage analysis was requested for all the biomarkers except for FISH. Although a full analysis was initially requested for FISH, most of the laboratories reported only a triage-based result. The main reason is that it was not clearly stated what was required before starting the exercise. Results show that most of the laboratories successfully discriminated unexposed and irradiated samples from each other without any overlap. A good agreement in the observed frequencies of translocations was observed but there was a tendency to overestimate the delivered doses. Efforts to improve the harmonization of this technique and subsequent exercises to elucidate the reason for this trend should be promoted.

RENEB Inter-Laboratory Comparison 2021: The Dicentric Chromosome Assay

After large-scale radiation accidents where many individuals are suspected to be exposed to ionizing radiation, biological and physical retrospective dosimetry assays are important tools to aid clinical decision making by categorizing individuals into unexposed/minimally, moderately or highly exposed groups. Quality-controlled inter-laboratory comparisons of simulated accident scenarios are regularly performed in the frame of the European legal association RENEB (Running the European Network of Biological and Physical retrospective Dosimetry) to optimize international networking and emergency readiness in case of large-scale radiation events. In total 33 laboratories from 22 countries around the world participated in the current RENEB inter-laboratory comparison 2021 for the dicentric chromosome assay. Blood was irradiated in vitro with X rays (240 kVp, 13 mA, ∼75 keV, 1 Gy/min) to simulate an acute, homogeneous whole-body exposure. Three blood samples (no. 1: 0 Gy, no. 2: 1.2 Gy, no. 3: 3.5 Gy) were sent to each participant and the task was to culture samples, to prepare slides and to assess radiation doses based on the observed dicentric yields from 50 manually or 150 semi-automatically scored metaphases (triage mode scoring). Approximately two-thirds of the participants applied calibration curves from irradiations with γ rays and about 1/3 from irradiations with X rays with varying energies. The categorization of the samples in clinically relevant groups corresponding to individuals that were unexposed/minimally (0-1 Gy), moderately (1-2 Gy) or highly exposed (>2 Gy) was successfully performed by all participants for sample no. 1 and no. 3 and by ≥74% for sample no. 2. However, while most participants estimated a dose of exactly 0 Gy for the sham-irradiated sample, the precise dose estimates of the samples irradiated with doses >0 Gy were systematically higher than the corresponding reference doses and showed a median deviation of 0.5 Gy (sample no. 2) and 0.95 Gy (sample no. 3) for manual scoring. By converting doses estimated based on γ-ray calibration curves to X-ray doses of a comparable mean photon energy as used in this exercise, the median deviation decreased to 0.27 Gy (sample no. 2) and 0.6 Gy (sample no. 3). The main aim of biological dosimetry in the case of a large-scale event is the categorization of individuals into clinically relevant groups, to aid clinical decision making. This task was successfully performed by all participants for the 0 Gy and 3.5 Gy samples and by 74% (manual scoring) and 80% (semi-automatic scoring) for the 1.2 Gy sample. Due to the accuracy of the dicentric chromosome assay and the high number of participating laboratories, a systematic shift of the dose estimates could be revealed. Differences in radiation quality (X ray vs. γ ray) between the test samples and the applied dose effect curves can partly explain the systematic shift. There might be several additional reasons for the observed bias (e.g., donor effects, transport, experimental conditions or the irradiation setup) and the analysis of these reasons provides great opportunities for future research. The participation of laboratories from countries around the world gave the opportunity to compare the results on an international level.

Low absolute peripheral blood CD4+ T-cell count predicts poor prognosis in R-CHOP-treated patients with diffuse large B-cell lymphoma

The absolute peripheral blood lymphocyte count at diagnosis is known to be a strong prognostic factor in patients with diffuse large B-cell lymphoma (DLBCL) treated with rituximab, cyclophosphamide, doxorubicin, vincristine and prednisone (R-CHOP), but it remains unclear as to which peripheral blood lymphocyte population is reflective of DLBCL prognosis. In this cohort, 355 patients with DLBCL treated with R-CHOP from 2006 to 2013 were analyzed. The low absolute CD4+ T-cell count (ACD4C) at diagnosis negatively correlated with the overall response rate and the complete response rate significantly (P<0.00001). An ACD4C<343 × 106/l had a significant negative impact on the 5-year progression-free survival and the overall survival as compared with an ACD4C⩾343 × 106/l (73.7% (95% confidence interval (CI)=66.7-79.5) versus 50.3% (95% CI=39.0-60.6), P<0.00001 and 83.3% (95% CI=77.1-88.0) versus 59.0% (95% CI=47.9-68.5), P<0.00000001, respectively). Multivariate analysis revealed that the ACD4C was an independent prognostic marker (hazard ratio=2.2 (95% CI=1.3-3.7), P<0.01). In conclusion, a low ACD4C at diagnosis served as an independent poor prognostic marker in patients with DLBCL.

Establishment of 2 human thyroid-carcinoma cell-lines (8305c, 8505c) bearing p53 gene-mutations

New cell lines, designated 8305C and 8505C, were established from undifferentiated thyroid carcinomas of a 67 year-old-female patient and a 78-year-old-female patient, respectively. Pathologically both these primary undifferentiated carcinoma tissues contained residual well differentiated components, suggesting well differentiated to undifferentiated carcinoma progression. Cell kinetic analysis indicate that the cell population doubling time is 43 h for 8305C and 36 h for 8505C. The saturation density at confluency is 5.7 x 10(4) cells/cm2 for 8305C and 1.1 x 10(5) cells/cm2 for 8505C. To identify genetic changes that may have occurred in these two cell lines, tumor suppressor genes p53, Rb, APC and MCC were analyzed. Sequence analysis confirmed a C:G to T:A transition at the first base of p53 gene codon 273 in 8305C and a C:G to G:C transversion at the first base of p53 codon 248 in 8505C. Polymerase chain reaction-loss of heterozygosity assays confirmed allelic deletion of p53 gene from the 8505C cell line. Loss of heterozygosity of other tumor suppressor genes were not observed. Given that p53 mutations associate with undifferentiated carcinoma but not with well differentiated carcinoma during multistep carcinogenesis of the thyroid, these cell lines should prove useful for research into the role of p53 gene mutations in malignant transformation.

Segmental copy-number variation observed in Japanese by array-CGH

Segmental copy-number variations (CNVs) may contribute to genetic variation in humans. In this study, we examined 80 unrelated Japanese individuals using a microarray (2,238 Bac-clones) based comparative genomic hybridization (array-CGH) assay. We found a total of 251 CNVs at 30 different regions in the genome; of these, 14 (termed 'rare' CNVs) were found individually located within distinct genomic regions of 14 individuals, while the remaining 16 CNV regions (termed 'polymorphic' CNVs) were observed in two or more individuals. The rare CNVs were confirmed by quantitative polymerase chain reactions, and characterized more precisely than in previous reports using array CGH. Distinctive features of these CNVs were observed: most prominent was that the majority of the rare CNVs presented on Bac-clones that did not overlap with regions of segmental duplication. About 90% of the polymorphic CNVs observed in this population had been previously identified, with the majority of those polymorphic CNVs located in regions of segmental duplication. It is likely, therefore, that rare and polymorphic CNVs arise through different genetic mechanisms. Since more than half of the rare CNVs are novel, it is also likely that different human populations bear different CNVs, as is the case for single-nucleotide-polymorphisms (SNPs) and insertion-deletion (indel) polymorphisms.

Increased susceptibility to apoptosis in CD45(+) myeloma cells accompanied by the increased expression of VDAC1

Expression of CD45 is quite variable in human myeloma cells and cell lines, such as U266, and CD45(+) U266 proliferates in response to a growth factor, interleukin-6. Here, we show that CD45(+) myeloma cell lines were more sensitive to various apoptotic stimuli, such as oxidative stress and endoplasmic reticulum (ER)-stress, than CD45(-) cells. Reactive oxygen species and calcium ion seemed to be involved in the susceptibility to apoptosis of CD45(+) U266. The activation of the src family kinases associated with CD45 phosphatase played an important role in the augmented apoptosis in CD45(+) U266 by oxidative stress. These results indicate that the CD45-expression renders myeloma cells competent for not only mitogenic but also apoptotic stimuli, resulting in either proliferation or apoptosis of CD45(+) myeloma cells dependently upon the circumstantial stimuli. Furthermore, voltage-dependent anion channel (VDAC) 1 was identified as a gene highly expressed in CD45(+) U266 by cDNA subtraction. The increased expression of VDAC1 seemed to augment the sensitivity to the ER-stress because the VDAC1-transfected U266 was more susceptible to the thapsigargin-induced apoptosis. Thus, CD45 expression accompanied by the increased VDAC1 expression sensitizes myeloma cells to the various extracellular stimuli that trigger apoptosis via the mitochondrial pathways.

Elevated in vivo frequencies of mutant T cells with altered functional expression of the T-cell receptor or hypoxanthine phosphoribosyltransferase genes in p53-deficient mice

We have studied the effects of a defect in the p53 gene on spontaneous and radiation-induced somatic mutation frequencies in vivo by measuring T-cell receptor (TCR) and hypoxanthine phosphoribosyltransferase (HPRT) mutant frequencies (MFs) in p53 deficient mice both before and after exposure to X-irradiation. In the absence of irradiation, the TCR and HPRT mutant frequencies were roughly two-fold higher in p53 null (-/-) mice than in wild-type (+/+) mice. Unexpectedly, the TCR and HPRT MFs were slightly lower in heterozygote p53 (+/-) than in wild-type (+/+) mice, however. After 2 weeks 2Gy whole body irradiation the TCR and HPRT MFs were about two-fold higher in the p53 null (-/-) and p53 (+/-) mice than in the wild-type. Taken together, these findings suggest that a defect in the p53 gene may lead to TCR and HPRT mutants being recovered at higher frequencies in both irradiated and unirradiated mice, but it should be emphasized that the effects we have observed are not particularly strong, albeit that they are statistically significant. Interestingly, several of the highest TCR MF values that we observed in the course of our experiments were recorded in p53 (-/-) animals that had developed thymomas and hence appeared to be cancer prone.

X-rays induce dose-dependent and cell cycle-independent accumulation of p21(sdi1/WAF1)

Cell cycle arrest at the G1 checkpoint is governed by a function of wild-type p53. We assessed the behavior of the sdi1 gene, which codes for a 21kDa potent inhibitor of cdk/cyclins, after X-irradiation. X-irradiation induced sdi1 mRNA accumulation and G1 arrest only in cells possessing wild-type p53. Elevation of p21(sdi1/WAF1) was preceded by p53 accumulation, which occurred despite p53 mRNA constancy in normal cells growing in the log phase. The quantity of accumulated p53 and p21(sdi1/WAF1) was radiation dose dependent. A decrease in the S phase cell population in normal cells observed after irradiation reached a minimum at less-than-maximum levels of p53 and p21(sdi1/WAF1). Furthermore, an accumulation of p53 and p21(sdi1/WAF1) was also observed when cells were synchronized in the G0, G1 and S phase and X-irradiated. These results indicated that an X-ray induced p53 and p21(sdi1/WAF1) accumulation mechanism exists throughout the cell cycle, and that the signal strength induced by X-irradiation is dose-dependent.

Differential regulation of human RecQ family helicases in cell transformation and cell cycle

Three human RecQ DNA helicases, WRN, BLM and RTS, are involved in the genetic disorders associated with genomic instability and a high incidence of cancer. RecQL1 and RecQL5 also belong to the human RecQ helicase family, but their correlation with genetic disorders, if any, is unknown. We report here that in human B cells transformed by Epstein-Barr virus (EBV), human fibroblasts and umbilical endothelial cells transformed by simian virus 40, the expression of WRN, BLM, RTS and RecQL1 was sharply up-regulated. In B cells this expression was stimulated within 5-40 h by the tumor promoting agent phorbol myristic acetate (PMA). Interestingly, RecQL5beta, an alternative splicing product of RecQL5 with a nuclear localization signal, is expressed in resting B cells without significant modulation of its synthesis by EBV or PMA, suggesting it has a role in resting cells. We also roughly determined the number of copies per cell for the five RecQ helicase in B cells. In addition, levels of the different RecQ helicases are modulated in different ways during the cell cycle of actively proliferating fibroblasts and umbilical endothelial cells. Our results support the view that the levels of WRN, BLM, RTS and RecQL1 are differentially up-regulated to guarantee genomic stability in cells that are transformed or actively proliferating.

Telomerase activity in hybrids between telomerase-negative and telomerase-positive immortal human cells is repressed in the different complementation groups but not in the same complementation group of immortality

The expression of telomerase is essential for cells to be immortalized, and most immortal cell lines possessed telomerase activity. Using the cell fusion technique, it has been shown that mortal and telomerase-negative phenotypes of normal cells are dominant over immortal and telomerase-positive phenotypes, suggesting that the normal cells possessed dominant repressor-type activity for telomerase expression. Several telomerase-negative immortal human cell lines were reported, in which telomerase-independent mechanisms was supposed to maintain telomere length. We aimed at seeing whether the telomerase-negative phenotype of these immortal cells is dominant over telomerase-positive phenotype of other immortal cells in correlation with cellular mortality. Results showed that, when telomerase-positive and -negative immortal parental cell lines belonging to the different complementation groups were fused, telomerase-negative mortal hybrid clones arose, i.e. telomerase-negative phenotype was dominant as well as mortal phenotype. However, when immortal hybrid cells arose from telomerase-positive and -negative immortal parents belonging to either the same or different complementation groups, they were all telomerase-positive, i.e. telomerase-negative phenotype appeared to be recessive. Telomerase-negative immortal hybrid was never established from any combinations between telomerase-negative and -positive immortal parental cells.

Simple, rapid, quantitative, and sensitive detection of telomere repeats in cell lysate by a hybridization protection assay

BACKGROUND

Detection of telomere repeats by Southern hybridization of genomic DNA is time consuming, and the reading of a mean terminal restriction fragment (TRF) length from a smear pattern of an autoradiogram can be inaccurate. We developed a hybridization protection assay (HPA) for telomere repeats.

METHODS

We heated 5 microL of DNA solution or 10 microL of cell or tissue lysate at 95 degrees C for 5 min, mixed it with 100 microL of hybridization solution containing 3 x 10(6) relative light units of acridinium ester-labeled probe, and incubated the mixture for 20 min at 60 degrees C. We then added 300 microL of selection buffer and incubated the mixture for 10 min at 60 degrees C to differentially hydrolyze unhybridized probe. Chemiluminescence was measured for 2 s per tube.

RESULTS

The amount of telomere repeats was assayed by HPA within linearity from 10 to 3000 ng of purified genomic DNA or from 1000 to 100 000 cell equivalents of lysate. To normalize the amount of DNA in lysate, the amount of Alu sequence was measured by HPA. A ratio of telomere to Alu (TA ratio) = 0.01 corresponded to approximately 2 kbp of mean TRF length determined by Southern blotting in cultured fibroblast and colorectal tissue samples. The TA ratio decreased from 0.06 to 0.02 with increasing division age from 30 to 90 population doubling levels of cultured human fetal fibroblasts. The assay required approximately 45 min from collection of cell or tissue samples.

CONCLUSIONS

The amount of telomere repeats was quantitatively measured by HPA in 10 ng of sheared genomic DNA or in the lysate of 1000 cells. This method is simple, rapid, quantitative, sensitive, and applicable to the measurement of telomere repeats in clinical samples such as needle biopsy specimen or as few as 1000 cells in body fluid or washings.

A hVti1 homologue: its expression depends on population doubling levels in both normal and SV40-transformed human fibroblasts

A cDNA clone was isolated by differential colony hybridization from a cDNA library prepared from life-extended SV40-transformed human fibroblasts. The clone, tentatively named N-10, was 1272 bp in length coding for 232 amino acids. Northern analysis revealed that the expression level of N-10 was increased in normal senescent and life-extended SV40-transformed fibroblasts than in their young counterparts but was not enhanced by growth arrest. The protein fused to GFP (green fluorescent protein) localized in cytoplasmic granule. Enforced expression of N-10 resulted in premature senescence in young fibroblasts. The deduced amino acid sequence of N-10 was identical to the recently reported hVti1 gene except in one amino acid: Asp24(GAC) was ours and Asn24 (AAC) was reported. Additional base differences were found, so we referred to our sequence as the hVti1 homologue. As hVti1 protein was suggested to be involved in the vesicle transport process, the homologue may be concerned with increased secretion of extracellular matrix and various cytokines associated with cellular senescence.

Gain-of-function p53 mutations enhance alteration of the T-cell receptor following X-irradiation, independently of the cell cycle and cell survival

Missense mutations are by the far the most common types of mutations found in p53 of human tumors, suggesting that mutant p53 proteins function either by abrogating wild-type function or by gaining new oncogenic functions. To distinguish between the dominant-negative effect and gain of new function of p53 missense mutants, we measured the ability of transfected missense mutant p53s in p53-null Jurkat cells to alter T-cell receptor (TCR) surface expression. The TCR is a key signal transduction moiety common to T lymphocytes and is one of the major sites for aberrations in T-cell leukemias/lymphomas. Three p53 mutants (248trp, 249ser, and 273his) enhanced the frequency of TCR mutants after graded doses of X-radiation compared to null p53 parent- and wild-type p53-possessing normal lymphocytes; the parent Jurkat and normal lymphocyte showed no difference. These enhancements were not the results of a change in radiosensitivity or in G1 checkpoint arrest characteristics. Therefore, the creation of this mutator phenotype by missense-type p53 mutations implies that a more direct mechanism, apart from changes of cell cycle kinetics or cell death, may be responsible for the selection of certain p53 point mutations, which eventually result in the tumorigenesis of the cell.

Increase in expression levels of interferon-inducible genes in senescent human diploid fibroblasts and in SV40-transformed human fibroblasts with extended lifespan

The normal human fibroblast line, TIG-3 which senesces at around 80 population doubling levels (PDLs), expressed interferon (IFN)-inducible genes such as 6-16, 2', 5'-oligoadenylate synthetase (2,5-A) and HLA B7 near the end of the proliferative lifespan. Other normal fibroblast line such as MRC-5 also expressed IFN-inducible genes when senesced. Clones transformed with SV40 T-antigen, which extended their proliferative lifespan by about 20-30 PDLs, also expressed IFN-inducible genes during their extended life. Anti-IFN-beta antibodies added in culture medium repressed the expression of IFN-inducible gene in both normal senescent and life-extended SV40-transformed cells. IFN-beta repressed DNA synthesis in normal TIG-3 and induced IFN-inducible genes in both normal and SV40-transformed TIG-3. Conditioned medium recovered from life-extended SV40-transformed cells contained IFN-beta, but not IFN-alpha, IFN-gamma or TNF-alpha and possessed an activity that inhibited DNA synthesis of young TIG-3. Addition of anti-IFN-beta antibodies into the medium enhanced the serum-induced DNA synthesis of near senescent (91% lifespan completed) TIG-3, while it neither induced DNA synthesis in fully senescent TIG-3 nor extended the proliferative lifespan of TIG-3. These results suggest that normal and SV40-transformed human fibroblasts increase expression of IFN-beta with increasing proliferative age especially near the end of their lifespan resulting in induction of IFN-inducible genes and possibly in growth repression.

The usefulness of severe combined immunodeficiency (SCID) mice to study human carcinogenesis

In the present study, we engrafted normal colonic epithelial and histologically diagnosed colonic adenomas from a familial adenomatous polyposis (FAP) patient into severe combined immunodeficient (SCID) mice and subsequently examined them histologically and molecular biologically. Successful engraftment and metastasis was observed. The facts that human normal colonic epithelium and adenomatous polyps can take in SCID mice indicates the possibility that this human SCID mouse system will be useful for investigating the dynamics of human carcinogenesis in various tissues.

Preparation of a subtractive cDNA library enriched in cDNAs which expressed at a high level in cultured senescent human fibroblasts

Subtracted cDNA library was prepared by subtracting [cDNA from young growing SV40-transformed human fibroblasts] from [cDNA from growing SV40-transformed fibroblasts in extended lifespan]. Isolated cDNA clones which expressed at high level in life-extended transformed cells also expressed at high level in normal senescent fibroblasts but did at low level in growing and growth-arrested young cells. Neither fibronectin nor procollagen cDNA was isolated. This cDNA library is useful for isolation of senescent-specific cDNA species which express at high level in normal senescent cells but at low level in growing and growth-arrested young cells, avoiding growth-arrest-specific cDNAs.

DNA-DNA subtractive cDNA cloning using oligo(dT)30-Latex and PCR: identification of cellular genes which are overexpressed in senescent human diploid fibroblasts

We previously reported an efficient method for subtractive cDNA cloning using oligo(dT)30-Latex and polymerase chain reaction (PCR) (E. Hara et al., Nucleic Acids Res. 19, 7097-7104, 1991). The subtraction was performed by hybridization between mRNA of cell type B and the cDNA made from mRNA of cell type A using an oligo(dT)30 primer covalently linked to Latex particles in an Eppendorf tube. The mRNA common to both types of cells could be removed by a brief centrifugation. In the present paper, the method was improved by using the sense strand DNA instead of mRNA for hybridization to cDNA covalently linked to the particles to minimize mRNA degradation and by optimizing the hybridization condition. The sense strand DNA was made from cDNA-oligo(dT)30-Latex by asymmetric PCR. Using the improved method, a subtractive cDNA library with longer cDNA inserts was successfully constructed with higher probability than the original method.

In vitro irradiation is able to cause RET oncogene rearrangement

Elevated risk of thyroid cancers among the atomic bomb survivors as compared to the nonexposed population suggests that some genetic events related to thyroid cancer must be caused by ionizing radiation. Accordingly, inducibility of RET oncogene rearrangements, i.e., the generation of the RET-PTC oncogene, specific for thyroid cancer, was investigated among human undifferentiated thyroid carcinoma cells (8505C), which do not have RET oncogene rearrangement, after 0, 10, 50, and 100 Gy of in vitro X-irradiation by means of reverse transcription polymerase chain reaction. After testing 10(8) cells at each dose point, 3 independent samples obtained with 50 Gy of X-irradiation and 6 independent samples obtained with 100 Gy of X-irradiation showed a rearranged RET oncogene amplified band. No rearranged transcripts were obtained from cells irradiated with 0 or 10 Gy. All of the transcripts were sequenced and found to contain the D10S170 and RET sequence. Interestingly, two types of rearrangements were included in these transcripts: one is specific for thyroid cancer and the other, which contains a 150-base pair insert, is atypical, not usually seen in vivo. This insert was found to be the exon of D10S170. Furthermore, in fibrosarcoma cells (HT1080), X-irradiation also induced RET oncogene rearrangements, which included the same two types of rearrangements observed in the X-irradiated thyroid cells (8505C). These results are in favor of the hypothesis that some radiation-induced thyroid cancers, including those among atomic bomb survivors, might have developed when a growth advantage was obtained through a specific form of RET oncogene rearrangement induced by radiation exposure.

Genetic alterations in thyroid tumor progression: association with p53 gene mutations

To identify the genetic events that must be involved in thyroid tumor progression, we initially investigated p53 gene alterations in 10 papillary adenocarcinomas, 4 follicular adenocarcinomas, and 8 undifferentiated carcinomas. Base substitutional mutations in exons 5 to 8 and loss of heterozygosity (LOH) of the p53 gene were not detected in papillary or follicular adenocarcinomas. However, 7 of 8 undifferentiated carcinomas were carrying base substitutional mutations, and LOH was detected in 3 of 5 informative cases. Furthermore, to verify that the p53 gene alterations are truly involved in tumor progression, DNA from individual foci of the four undifferentiated carcinomas coexisting with a differentiated focus and from one follicular adenocarcinoma with an undifferentiated focus was analyzed by direct sequencing and polymerase-chain-reaction-restriction-fragment-length polymorphism (PCR-RFLP). Base substitutional mutations in the p53 gene from exons 5 to 8 were identified exclusively in the undifferentiated foci, but not in the differentiated foci. LOH was observed in 3 of 4 informative undifferentiated foci. In one of these positive cases, LOH was observed in both papillary adenocarcinoma and undifferentiated carcinoma. However, a p53 gene mutation at codon 248 was detected in the undifferentiated carcinoma but not in the papillary adenocarcinoma. The results imply that LOH occurs first in papillary adenocarcinoma followed by a p53 mutation during the transition from papillary adenocarcinoma to undifferentiated carcinoma. Maintenance of LOH during tumor progression excludes the possibility that these different histological foci are derived from different origins and represents molecular evidence that undifferentiated carcinoma is very likely derived from preexisting papillary adenocarcinoma. Furthermore, these results strongly suggest that the mutated p53 gene plays a crucial role in de-differentiation during the progression of thyroid tumors.

Unique association of p53 mutations with undifferentiated but not with differentiated carcinomas of the thyroid gland

Thyroid neoplasms show a wide variety of lesions varying from slowly growing differentiated adenocarcinomas to rapidly proliferating undifferentiated carcinomas. There has been some histopathological evidence that the undifferentiated thyroid carcinomas are derived from differentiated carcinomas. Moreover, it is suspected that some genetic events might be associated with such changes. In the present study, mutations in the p53 gene were investigated by direct sequencing analysis after polymerase chain reaction amplification of exons 5 to 8, using paraffin-embedded primary tumors and cultured cells. No mutations in exons 5 to 8 were detected in 10 differentiated papillary adenocarcinomas, whereas 6 of 7 undifferentiated carcinomas were found to carry base substitution mutations. Sequencing analysis confirmed mutations at codons 135 (TGC----TGT), 141 (CCC----CCT), 178 (CAC----GAC), 213 (CGA----TGA), 248 (CGG----CAG, CGG----TGG), and 273 (CGT----TGT). The spectrum of mutations (G:C to A:T transitions in 7 of 8) might be a specific feature of the spontaneous cancers. The results strongly suggest that, in human thyroid glands, p53 mutations play a crucial role in the progression of differentiated carcinomas to undifferentiated ones.

SV40 T-antigen is required for maintenance of immortal growth in SV40-transformed human fibroblasts

Two lines of immortal human fibroblasts were isolated following transfection of TIG-3 cells with plasmid DNA, pMT-1ODtsA, that contained SV40 early gene with a deletion in replication origin and ts mutation in coding sequence for T-antigen. These cells continued proliferation at 34 degrees C, over 565 population doubling level (PDL) which is far over the limited division potential of untransformed normal TIG-3 of 70-80 PDL. When the culture temperature was shifted to 40 degrees C after 70 PDL, they ceased proliferation immediately. One of these immortal clones, SVts8, lost its ts phenotype after retransformation with wtT-antigen gene. These results indicated that the function of intact T-antigen is required for maintenance of immortal proliferation, at least in one of the SV40 transformed immortal clones.

[Spinal flexibility and activities of daily living for the thoracic and lumbar spinal cord injured--comparison of a non operated group with an internal spinal fused group]

There has been a great argument in selecting conservative treatment or surgical repair for the spinal cord injury as an early stage treatment. The purpose of medical treatment is to bring a patient back to the society as soon as possible by early intervention and rehabilitation, while preventing complications of the injury. We are faced with a difficulty in determining the superiority between conservative treatment and surgical repair, since no comparative statistical analysis has been available among various rehabilitation methods for the spinal cord injury. We treated 171 patients in the past with traumatic thoracic or lumbar spinal cord injury who were submitted to our hospital for the ADL training purposes. We selected and studied 34 complete paraplegic cases with no complications who started receiving ADL training within 2 months period after the injury from among these cases. (1) Non-ope group was superior in spinal flexibility to internally spinal fused group. (2) Non-ope group reached ADL independence 1.4 months earlier than I.S.F. in case of upper thoracic injury. ADL independence was reached almost at the same time in the lower thoracic injury cases by either treatment. Above all, it is concluded that conservative treatment is more helpful to establish rehabilitation in shorter length of time than surgical repair.

Direct nerve crossing with the intercostal nerve to treat avulsion injuries of the brachial plexus

One hundred seventy-nine patients with root avulsion brachial plexus injuries were treated with direct nerve crossing with the intercostal nerve and 159 cases were followed more than 1 1/2 years after the operation. When suture was done to the musculocutaneous nerve, 90% of 10 children who had operation within 7 months of injury and 81.8% of 110 adults, younger than 40 years with operation within 6 months of injury regained grade 3 or 4 elbow flexion power. This direct method seems to produce better results than those of nerve crossing, which uses intermediary nerve grafts.

Usefulness of myelography in brachial plexus injuries

Ninety brachial plexus lesions have been examined by myelography and the results classified into six types. These were compared against the level of lesion found at exploration of the brachial plexus with electrophysiological investigations carried out during the operation. The results show that myelography can be a reliable and useful pre-exploratory measure to assess the level of the lesion of each injured root.

Expiratory activity in transferred intercostal nerves in brachial plexus injury patients

Involuntary activity of transferred intercostal motor units was examined in patients with brachial plexus injury. Since the internal intercostal nerves were detached from the thorax to reinnervate the musculus biceps brachii, it was possible to record pure intercostal motor activity in humans. Respiratory activity was seen in the latter part of the expiratory phase, thus dividing the phase into two substages (E1 and E2) by the onset of the activity. CO2 rebreathing prolonged the duration of the intercostal motor activity and increased the tidal activity as determined from the integration curve. There was a close linear correlation between these two variables. These observations indicate that expiratory activity and its duration are actively controlled in humans.

Recent trends in orthopaedics in Japan

Orthopedic surgery in Japan has developed markedly since the end of the Second World War and at present many subspecialty study groups cover various aspects of basic orthopedic and clinical research. The main trends and topics of orthopedic surgery in Japan are presented as examples of recent or representative works.

Ossification of the posterior longitudinal ligament of the spine

Ossification of the posterior longitudinal ligament of the spine (OPLL) is a newly recognized entity. As the incidence of this disease was exceptionally high in Japan, the Japanese Ministry of Public Health and Welfare instituted a special commission for the investigation of this perplexing disease; since 1975 this committee has performed an intensive study of 2100 patients with OPLL in Japan. An epidemiologic study was conducted by this group in Japan and in eastern Asiatic countries. Symptoms and disabilities caused by the disease were described. Roentgenographic findings were classified as continuous, segmental, mixed, or localized. OPLL at the thoracic and lumbar levels combined with ossification of the yellow ligament was described, and the risk of spinal cord damage as well as the importance of tomography and computerized tomographic scanning were stressed. No conclusions were reached concerning etiology, but common findings included a generalized hyperostotic tendency, a tendency for abnormal glucose metabolism, and low enteral calcium absorption. A relatively high hereditary occurrence was noted. Conservative and surgical treatment methods were described, with particular reference to spinal canal-widening operations.

Brachial plexus injuries. Prognosis of postganglionic lesions

One hundred ninety-eight cases of postganglionic brachial plexus injury with no signs of combined damage to preganglionic sites were treated conservatively. Among them, 50 whole, 32 upper and 13 lower type injuries were followed up for at least 2 years and the course of the progression of the individual muscle was observed. In the whole type, 44% showed good functional recovery, although some of them needed reconstructive surgery. Thirty-eight percent recovered usefully only in the muscles innervated by upper roots. Three out of 50 cases did not recover at all. There were no particular differences between the whole and upper types with regard to the recovery rate of the arm muscles. However, the upper type showed better functional recovery than the whole type. If the muscles innervated by upper roots could gain a strength of M1 before 9 months after injury, and muscles innervated by lower roots reached M1 before 12 months, their final results were more than M3. But muscles with a strength of less than M2 at 18 months did not recover to more than M3. The muscular power at 24 months was almost the same as the final results. About half of the postganglionic brachial plexus injuries which did not combine preganglionic lesions showed favorable spontaneous recovery with conservative treatment. At the exploration of the brachial plexus, if the somatosensory evoked potential test is positive, which negates the possibility of root avulsion, and also if there is no definite discontinuity of the postganglionic nerves, it should be treated conservatively.(ABSTRACT TRUNCATED AT 250 WORDS)

[Effect of eel calcitonin derivative (elcatonin) in osteoporosis]

Calcitonin has been considered to be useful in the treatment of osteoporosis due to its remarkable suppressive action on bone resorption as well as its putative stimulative effect on bone formation. However, its usefullness, especially the effect for decreasing the loss of bone mass in osteoporosis has not been proved substantially. We have studied this point using eel calcitonin derivative, elcatonin , in relatively low doses with and without calcium supplement. Bone mass was evaluated by microdensitometry of the roentgenograms of the second metacarpal bone. One hundred and thirty cases of postmenopausal and senile osteoporotics were divided into the following four groups and studied for six months: A) calcium and elcatonin treated group, B) calcium treated group, C) elcatonin treated group, D) control group. Elcatonin was administered intramuscularly 10 units once a week, and calcium was given 700 mg for every day. The results of metacarpal densitometry revealed the signs of significant increase of the bone mass in the calcium and elcatonin treated (A) group compared with the control (D) group, while the changes in the other groups (B and C) were not significant. It was shown that elcatonin had the significant analgesic effect for the back pain in the patients. Serum iPTH was not increased and the antibody for elcatonin was not detected in elcatonin treated patients. Although the study period is rather short, necessitating further studies, at present, our study suggests that the use of calcitonin with calcium supplements had the place in the treatment of osteoporosis.

The treatment of congenital dislocation of the knee with the Pavlik harness

We have used the Pavlik harness in the treatment of congenital dislocation of the knee in six knees in five patients, with satisfactory results. We believe that the muscles in the thigh which cross both the hip and knee joints, the rectus femoris and hamstrings, play an important role in the spontaneous reduction of the joint. Full correction is not always obtained, our results are comparable with those described by other authors. We consider that the advantages of using the harness are that a spontaneous correction can be obtained, maximal correction can be obtained after three months of treatment and the method is safer than others used.

Pulmonary function before and after surgical correction of scoliosis

We compared the preoperative and postoperative pulmonary function of thirty-one scoliotic patients ranging in age from nine to twenty-five years. The mean postoperative follow-up period was three years and eight months. Twenty patients were treated by a posterior procedure with Harrington instrumentation. At more than two years postoperatively a significant improvement in the pulmonary function was noted, particularly in patients with a preoperative curve of less than 90 degrees (Cobb angle) and in those in whom the correction was greater than 30 per cent. The remaining eleven patients were treated by an anterior procedure, primarily a Dwyer operation, with or without posterior Harrington instrumentation. These patients manifested no remarkable improvement in pulmonary function more than two years after surgery; three patients showed deterioration. The results of tests performed less than two years postoperatively showed no improvement in pulmonary function, irrespective of the types of assessments used. We attribute our long-term improvements to a shortening of the postoperative period of plaster-cast immobilization and to the use of a plastic corset which allowed relatively free chest motion. We suggest that the Dwyer operation should be restricted to patients with a severe spinal deformity.

Investigation of brachial plexus injuries by intraoperative cortical somatosensory evoked potentials

With the intention of estimating the extent and site of damage in brachial plexus injuries which involve close to the root outlet and also the distal portion, cortical somatosensory evoked potentials (SEP) were recorded in 21 patients by directly stimulating the exposed brachial plexus. In 38 avulsed nerve roots which showed positive sensory action potentials (SNAP)/nerve action potentials (NAP) in their peripheral part, 15 roots (nine patients) were apparently in continuity and confirmed as root avulsion injury by the absence of cortical SEP. However, 11 roots (ten patients) which showed neither SNAP nor SEP would suggest either extensive lesions involving root and more distal segment or a combination of root avulsion and postganglionic injury. Fourteen patients who showed a positive Tinel's sign had at least one root with a postganglionic type lesion, but cortical SEP evoked by stimulation of the most proximal root zone sometimes revealed a reduced amplitude and prolonged latency. This would indicate the retrograde extension of damage. To confirm the extent and degree of the nerve lesions in brachial plexus injuries, an intraoperative SEP and NAP recording is very useful, practical, and also indispensable.

[Roentgenological measurement of the cervical vertebral bodies in ossification of the posterior longitudinal ligament (OPLL) and cervical spondylosis (CS) (author's transl)]

Many studies of the pathogenesis of ossification of posterior longitudinal ligaments (OPLL) have been reported, and both general and local factors have been pointed out. In case a longitudinal ligament is affected by both the general and local OPLL factors for many years, the shape and size of the cervical vertebral bodies and the arrangement of the cervical spinal column might be affected. The relation between OPLL and disc degeneration, the morphology of the facet joint and the change of longitudinal ligament tension has been reported by many authors. But the relation between OPLL and the shape, size and arrangement of cervical vertebral bodies has not been reported. We selected X-ray films of the lateral view of cervical spines which had been taken at our hospital since 1975. The subjects consisted of 190 cases in Group I and 189 cases in Group II. Half of Group I had OPLL, of which 71 were males and 24 females. The other half of Group I was composed of 95 cases (CS) of cervical spondylosis of the same sex and age distribution. Group II comprised 189 cases, all males aged 49 yrs. Of them, 41 were OPLL cases, 102 CS, and 46 normal subjects. The X-ray films of Group II were taken during medical examinations. The height, antero-posterior diameter of the cervical vertebral bodies and the antero-posterior diameter of the cervical spinal canals were measured and examined for kyphosis between the two neighbouring cervical vertebral bodies, disc space narrowing and Barsony ossification. The height and antero-posterior diameter of the cervical vertebral bodies were compared among the following groups. 1) the 3 groups divided according to age (-49,50-59,60-75 yrs.), 2) segmental type with non-segmental type, 3) OPLL only at C3 and C4 with OPLL only at C5, C6, and C7. The results were as follows: The cervical vertebral bodies of OPLL were taller and wider than those of CS. Cervical vertebral bodies of the older group were shorter and wider than those of the younger groups in both OPLL and CS. THe relative height (C3 = I) of OPLL group was very close to Normal group. The cervical vertebral bodies of non-segmental type were taller but not wider than those of segmental type of OPLL group. The C3 and C4 vertebral bodies with OPLL only at C3 and C4 were taller, but not wider than those with OPLL only at C5, C6 and C7. The antero-posterior diameter of cervical spinal canal of OPLL was narrower than CS group. The above data indicate the following: 1) With advance in age, cervical vertebral bodies become lower and wider. 2) The cervical vertebral body of OPLL is taller and wider than that of CS. 3) The level of OPLL and the type of OPLL have a relation to the height of cervical vertebral body. 4) The cervical vertebral bodies which have OPLL are wider than non-OPLL. But the level and the type of OPLL have no relation with the A-P diameter of the cervical vertebral body.

Meitens' syndrome

This paper reports on Mietens' syndrome which is characterized by mental retardation, growth failure, flexion contracture of the elbows, dislocation of the radius, abnormally short ulna and radius, bilateral corneal opacity, horizontal and rotational nystagmus, strabismus and a small pointed nose with depressed root. This is the second on the Mietens' syndrome.