Aberrant CDKN1A transcriptional response associates with abnormal sensitivity to radiation treatment

Normal tissue reactions to radiation therapy vary in severity among patients and cannot be accurately predicted, limiting treatment doses. The existence of heritable radiosensitivity syndromes suggests that normal tissue reaction severity is determined, at least in part, by genetic factors and these may be revealed by differences in gene expression. To test this hypothesis, peripheral blood lymphocyte cultures from 22 breast cancer patients with either minimal (11) or very severe acute skin reactions (11) have been used to analyse gene expression. Basal and post-irradiation expression of four radiation-responsive genes (CDKN1A, GADD45A, CCNB1, and BBC3) was determined by quantitative real-time PCR in T-cell cultures established from the two patient groups before radiotherapy. Relative expression levels of BBC3, CCNB1, and GADD45A 2 h following 2 Gy X-rays did not discriminate between groups. However, post-irradiation expression response was significantly reduced for CDKN1A (P<0.002) in severe reactors compared to normal. Prediction of reaction severity of approximately 91% of individuals sampled was achieved using this end point. Analysis of TP53 Arg72Pro and CDKN1A Ser31Arg single nucleotide polymorphisms did not show any significant association with reaction sensitivity. Although these results require confirmation and extension, this study demonstrates the possibility of predicting the severity of acute skin radiation toxicity in simple tests.

Evidence for complex multigenic inheritance of radiation AML susceptibility in mice revealed using a surrogate phenotypic assay

The mapping of genes which affect individual cancer risk is an important but complex challenge. A surrogate assay of susceptibility to radiation-induced acute myeloid leukaemia (AML) in the mouse based on chromosomal radiosensitivity has been developed and validated. This assay was applied to the mapping of radiation-induced AML risk modifier loci by association with microsatellite markers. A region on chromosome (chr) 18 with strong association is identified and confirmed by backcross analysis. Additional loci on chrs 8 and 13 show significant association. A key candidate gene Rbbp8 on chr18 is identified. Rbbp8 is shown to be upregulated in response to X-irradiation in the AML sensitive CBA strain but not AML resistant C57BL/6 strain. This study demonstrates the strength of utilizing surrogate endpoints of cancer susceptibility in the mapping of mouse loci and identifies additional loci that may affect radiation cancer risk.

The influence of dietary flaxseed and other grains, fruits and vegetables on the frequency of spontaneous chromosomal damage in mice

Spontaneous genetic damage, whether mutations or chromosomal aberrations, undoubtedly arise from a variety of sources including replication errors, oxidative damage, background radiation, and chemical exposure. Given the numerous correlations between diet and cancer, it seemed possible that diet could influence the spontaneous rate of DNA damage and its genetic consequences. Since diets high in vegetables, fruits, and grains are associated with lower rates of cancer, we supplemented the diets of mice and measured the frequency of micronuclei in the peripheral blood. Micronuclei arise from broken chromosomes or chromosome loss in the erythroblast. They are first seen in the short reticulocyte stage of the red blood cell but persist for the entire 30-day lifespan of the cell in mice. C57Bl mice were placed on a defined diet (AIN-93G) supplemented to 20% final dry weight with grains or freeze-dried fruits or vegetables. The micronucleus frequency was measured in a pre-exposure blood sample and every 2 weeks thereafter for 6 weeks. This was possible in spite of the low spontaneous frequency of 1/1000-2/1000 cells by the use of a novel flow cytometric method, which permitted the analysis of both the mature red blood cells and reticulocytes. Of the foods tested, flaxseed proved to be the most protective by reducing the incidence of micronuclei in both the reticulocyte and normochromatic erythrocyte cell populations by 30 and 11%, respectively. The results show that at least one class of spontaneous genetic damage can be modified by diet and suggests that short-term experiments with small numbers of animals can be used to identify dietary anticarcinogens that may influence human cancer rates.

Effect of dietary supplementation on the frequency of spontaneous lacZ mutations in the developing colon

Epidemiological studies have demonstrated that dietary modifications can reduce the incidence of cancer. Specifically, diets high in vegetables and fruits are associated with lower rates of cancer at many sites. Somatic mutations have a critical role in carcinogenesis suggesting the use of in vivo mutation assays as an alternative approach to studying the relationship between diet and cancer. Since the rate of accumulation of spontaneous mutations is highest during growth and development early in life, we tested whether certain foods as dietary supplements could reduce the rate of mutation during this period using lacZ transgenic mice. Pregnant female mice were placed on a control diet or a diet supplemented to 20% final dry weight with broccoli, cabbage, carrots, flaxseed, green peas, green peppers, oranges or strawberries for the entire duration of their pregnancy and lactation. Mutation frequencies were subsequently measured at the lacZ transgene in colonic epithelial cells of the offspring at 3 weeks of age. A small number of measurements were also made on siblings at 8 weeks of age. While the control AIN-96G diet on its own resulted in lower mutant frequencies than had been observed in earlier experiments with lab chow, no significant reduction in mutant frequencies was detected for any of the foods tested as compared to the AIN-93G diet alone. Significantly more mutations were found at 3 weeks of age in mice fed diets supplemented with broccoli or oranges, but the result with oranges may be the result of jackpot mutations.

Accuracy in tunnel placement for ACL reconstruction. Comparison of traditional arthroscopic and computer-assisted navigation techniques

The purpose of this randomized, prospective study was to compare accuracy in tunnel placement as performed with a traditional arthroscopic anterior cruciate ligament (ACL) reconstruction technique and with KneeNavTM ACL, a computer-assisted surgical navigation technique. Two surgeons experienced in ACL reconstruction, but inexperienced in computer-assisted surgical navigation technique, each randomly used traditional arthroscopic guides or KneeNavTM ACL to drill a tunnel in twenty identical foam knees. Placement of the resulting tibial and femoral tunnels was measured with a computer-assisted digitizing method and compared to traditional biplanar radiographs. Statistical analysis with Student's t-test was used to compare the distance from the ideal tunnel placement to the femoral and tibial tunnels. Accuracy of tunnel placement with KneeNavTM ACL was significantly better than that obtained with the traditional arthroscopic technique. Distances from the ideal tunnel placement to the femoral and tibial tunnels were 4.2 +/- 1.8 mm (mean +/- SD) and 4.9 +/- 2.3 mm, respectively, for the traditional arthroscopic technique, and 2.7 +/- 1.9 mm (femur) and 3.4 +/- 2.3 mm (tibia) for KneeNavTM ACL. These differences were statistically different. Tunnel placement for ACL reconstruction with KneeNavTM ACL, an image-based, computer-assisted surgical navigation device with a simple and intuitive interface, was more accurate than with the traditional arthroscopic technique.

Analysis of loss of heterozygosity in lymphoma and leukaemia arising in F1 hybrid mice locates a common region of chromosome 4 loss

Previous studies have identified five lymphoma-related tumour suppressor gene regions on murine chromosome 4. Using detailed allelotype analysis on a range of lympho-haematopoietic tumour types arising in F1 hybrid mice, we now show a consistent pattern of loss of heterozygosity (LOH) which identifies a common region of loss delineated by microsatellites D4Mit21 and D4Mit53 on proximal chromosome 4. This critical segment corresponds to the thymic lymphoma tumour suppressor region 5 (TLSR5) identified in an earlier study. Tumours of this type have also been reported as showing allelic loss from the Trp53 and Ikaros regions on chromosome 11. In the present study, only a small fraction of tumours showed LOH in the Ikaros region, while a minority of lymphomas, but not acute myeloid leukaemias, showed allelic loss of the chromosome 11 segment encoding Trp53. These and other data indicate strongly that the genomic regions identified as showing recurrent LOH depend on the genetic background of the mice. Overall, the results indicate a key role for a tumour suppressor gene(s) encoded in an approximately 3 cM segment on proximal chromosome 4 and provide an experimental basis for the further investigation of the functional role of candidate genes which include Pax5 and Tgfbr1.

Conditional immortalization of freshly isolated human mammary fibroblasts and endothelial cells

Reports differ as to whether reconstitution of telomerase activity alone is sufficient for immortalization of different types of human somatic cells or whether additional activities encoded by other "immortalizing" genes are also required. Here we show that ectopic expression of either the catalytic subunit of human telomerase (hTERT) or a temperature-sensitive mutant (U19tsA58) of simian virus 40 large-tumor antigen alone was not sufficient for immortalization of freshly isolated normal adult human mammary fibroblasts and endothelial cells. However, a combination of both genes resulted in the efficient generation of immortal cell lines irrespective of the order in which they were introduced or whether they were introduced early or late in the normal proliferative lifespan of the cultures. The order and timing of transduction, however, did influence genomic stability. Karyotype analysis indicated that introduction of both transgenes at early passage, with hTERT first, yielded diploid cell lines. Temperature-shift experiments revealed that maintenance of the immortalized state depended on continued expression of functional U19tsA58 large-tumor antigen, with hTERT alone unable to maintain growth at nonpermissive temperatures for U19tsA58 large-tumor antigen. Such conditional diploid lines may provide a useful resource for both cell engineering and for studies on immortalization and in vitro transformation.

Low- or high-intensity strength training partially restores impaired quadriceps force accuracy and steadiness in aged adults

Because many daily tasks are executed at only a fraction of maximal strength, an understanding of submaximal force control may be important for improving function in aged adults. We compared the effects of low- and high-intensity (LI and HI, respectively) strength training on maximal and explosive strength and on the accuracy (force error) and steadiness (variability) of submaximal quadriceps force in elderly humans. Older subjects (age, 72 years; n = 27) had 57% lower maximal strength in comparison with young subjects (age, 21 years; n = 10). Older subjects had 190% (19 N), 50% (1 N), and 80% (4 N) more force error in matching 25 N of quadriceps force during eccentric, isometric, and concentric contractions, and had 157%, 0%, and 60% more variability in these forces compared with young subjects. Force error and force variability were correlated with each other but not with maximal strength. Thirty sessions of LI (n = 9 participants) or HI (n = 9 participants) training of equal total work increased maximal strength in the older subjects by 29%. Training also significantly reduced force error and variability--by 31% and 30%, respectively--of eccentric and concentric contractions. A control group of older subjects (n = 9) showed no significant changes in any variables. LI or HI strength training was equally effective in partially restoring elderly adults' maximal strength and control of submaximal force.

Hydroxylation of biphenyl by the yeast Trichosporon mucoides

Hydroxylation of biphenyl by the dibenzofuran-degrading yeast Trichosporon mucoides SBUG 801 was studied. Glucose-grown cells degraded 40% of the biphenyl added within the first 24 h of incubation. The first step in the biotransformation pathway was the monohydroxylation of the biaryl compound to produce 2-, 3-, and 4-hydroxybiphenyl. Further oxidation produced seven dihydroxylated intermediates; the second hydroxyl group was added either on the aromatic ring already hydroxylated or on the second ring. Of all metabolites, 2,5-dihydroxybiphenyl accumulated in the supernatant in the highest concentration. The initial hydroxylation favors the 4-position to produce 4-hydroxybiphenyl, which is subsequently hydroxylated to form 3,4-dihydroxybiphenyl. When biphenyl was replaced as a substrate by 4-hydroxybiphenyl, further hydroxylation of the intermediate 3,4-dihydroxybiphenyl resulted in 3,4,4'-trihydroxybiphenyl. Incubation of T. mucoides with biphenyl and 18O2 indicated a monooxygenase-catalyzed reaction in the oxidation of biphenyl. The hydroxylation was inhibited by 1-aminobenzotriazole and metyrapone, known cytochrome P450 inhibitors. These results are very similar to those observed in the biotransformation of biphenyl in mammals.

Loss of heterozygosity in spontaneous and X-ray-induced intestinal tumors arising in F1 hybrid min mice: evidence for sequential loss of APC(+) and Dpc4 in tumor development

Min (multiple intestinal neoplasia) mice carry a mutant allele of the murine Apc (adenomatous polyposis coli) locus and are predisposed to intestinal adenoma formation in the intestinal tract. Early studies have shown complete loss of function of Apc by whole chromosome loss on the tumor-sensitive C57BL/6J genetic background and in AKR x B6 F1 hybrids. Gamma-radiation-induced chromosomal losses focus the critical region on wt Apc, but because of the limited number of polymorphic markers used, no other critical regions of loss on chromosome 18 were identified. Using intestinal tumors arising spontaneously and induced by X-rays in CBA/H x C57BL/6J F1 hybrid mice and high-resolution microsatellite loss of heterozygosity (LOH) techniques, we provide mapping data for wt Apc loss, which confirms and extends earlier observations. In addition, high-frequency loss events at the Dpc4 locus were found in both spontaneous and radiation-induced tumors. These data identified LOH of Dpc4 as a critical secondary event following complete functional loss of Apc. LOH across the Trp53 genomic region of chromosome 11 was not observed. No LOH was recorded for the Mom1 candidate gene Pla2g2a or for 9 out of 10 polymorphic markers from the Mom1 genomic region on murine chromosome 4. One marker mapping distal to Pla2g2a showed LOH in a small minority of spontaneous tumors. These data support the contention that Mom1 does not act as a classical tumor suppressor. Overall, our data indicates a significant role for Dpc4 mutation in intestinal tumor progression in the mouse and provides further evidence for the importance of interstitial chromosome losses in radiation tumorigenesis.

Somatic cell hybrids for high-density mapping of chromosome 2 breakpoints in radiation-induced myeloid leukemia cell lines from inbred mice

Chromosome 2 (chr 2) deletions are recurrent abnormalities in acute myeloid leukemia (AML) induced by ionizing radiation in the mouse. The localization of deletion sites has proven extremely useful in providing information on the molecular mechanisms of leukemogenesis. The models available for the study of AML are mostly represented by inbred mouse strains, in which the molecular resolution of breakpoints is problematic. In this study, we have examined five leukemic cell lines exhibiting hemizygous chr 2 loss, derived from CBA, C3H, or (C57BLxCBA/H) F1 mice in which AML had been induced by a whole-body dose of radiation. By application of a somatic cell hybridization technique, we have generated interspecific cell hybrids retaining the deleted murine chr 2 homologue. This strategy permitted a very detailed genetic analysis allowing the utilization of any genetic marker on chr 2 without a requirement for polymorphism. Somatic cell hybrid clones were subjected to a high-density polymerase chain reaction-based microsatellite screening using 62-106 informative markers for each cell line. Detailed maps accurately defining chr 2 breakpoints were obtained. The identification of critical breakpoint markers allowed the construction of partial yeast artificial chromosome contigs across chr 2 breakpoints. These maps represent an essential resource for cloning of the breakpoint regions.

Foregone health care among adolescents

CONTEXT

No annual national population estimates exist of the numbers of adolescents who think they need but do not receive health care or their risk of health problems.

OBJECTIVE

To describe the proportion of adolescents who report foregone health care each year and the influence of sociodemographic factors, insurance status, past health care, and health risks/behaviors on foregone care.

DESIGN

Cross-sectional analyses of data from wave 1 of the National Longitudinal Study of Adolescent Health, conducted during 1995.

SETTING

In-home interviews conducted throughout the United States.

PARTICIPANTS

Of 27000 adolescents in grades 7 through 12 who were invited to participate, 20746 (76.8%) completed the in-home interview.

MAIN OUTCOME MEASURE

Reported foregone health care in the preceding year by individual and family characteristics, insurance status, past health care, health/behavior risk factors, and symptoms.

RESULTS

On average, 2268 (18.7%) of 12 079 adolescents reported foregone health care within the past year. Factors associated with decreased risk of foregone care included continuous private or public insurance (adjusted relative risk [95% confidence interval], 0.64 [0.50-0.82] to 0.82 [0.70-0.96]), and having a physical examination within the past year (0.87 [0.78-0.97] for male and 0.79 [0.70-0.88] for female adolescents). Factors associated with increased risk of foregone care included older age (1.12 [1.06-1.15] for male), minority race/ethnicity (1.25 [1.06-1.46] to 1.50 [1.30-1.73]), single-parent home (1.31 [1.18-1.46] for female), and disability (2.03 [1.61-2.52] for male and 1.66 [1.20-2.10] for female). Adolescents participating in the following behaviors were more likely to report foregone care than those who did not: daily cigarette use (26.0% vs 16.8%; 1.34 [1.16-1.55]), frequent alcohol use (30.3% vs 18.1%; 1.34 [1.11-1.62] for male), and sexual intercourse (25.1% vs 15.1%; 1.23 [1.09-1.39] for male and 1.39 [1.23-1.56] for female). From 32.4% to 38.2% of adolescents with symptoms suggesting health problems reported foregone care (1.61 [1.13-2.26] to 2.03 [1.81-2.28]).

CONCLUSIONS

Our study suggests that adolescents who forego care are at increased risk of physical and mental health problems. Efforts to improve adolescent health through health care should address factors influencing foregone care.

The combination paclitaxel, carboplatin and megestrol acetate is effective in women with recurrent uterine papillary serous adenocarcinoma

Uterine papillary serous adenocarcinoma is an uncommon and very aggressive type of endometrial cancer. A 76-year-old patient diagnosed with recurrent uterine papillary serous adenocarcinoma was prescribed megesterol acetate (160 mg daily), paclitaxel (135 mg/m2) and carboplatin (area under the concentration-time curve of 5) every 4 weeks for 4 courses. She demonstrated complete clinical response that was maintained for longer than 6 months with minimal toxicity. The combination megesterol acetate, paclitaxel and carboplatin may be effective in women with recurrent uterine papillary serous adenocarcinoma.

Molecular mapping of chromosome 2 deletions in murine radiation-induced AML localizes a putative tumor suppressor gene to a 1.0 cM region homologous to human chromosome segment 11p11-12

Radiation-induced acute myeloid leukemias (AMLs) in the mouse are characterized by chromosome 2 deletions. Previous studies showed that a minimal deleted region (mdr) of approximately 6.5 cM is lost from one homologue in chromosome 2-deleted AMLs. An AML tumor suppressor gene is proposed to map within this mdr. In this study, we refine the mdr to a I cM interval between markers D2Mit126 and D2Mit185 by microsatellite analysis of 21 primary radiation-induced F I AMLs. The construction of a partial yeast artificial chromosome (YAC) contig spanning the mdr and the location of six known genes indicated that the 1 cM mdr is homologous to human 11p11-12, a region implicated in some human AMLs. Screening of five cell lines derived from primary radiation-induced AMLs for homozygous loss of microsatellites and genes mapping within the mdr revealed loss of both copies of the hemopoietic tissue-specific transcription factor Sfpi1(PU.1/Spi1) in one cell line. Studies of primary and F1 AMLs failed to implicate Sfpi1 as the AML tumor suppressor gene. YAC contig construction, together with data suggesting that the critical gene flanks Sfpi1, represents significant progress toward identifying an AML tumor suppressor gene.

New approaches to antimutagenesis

One of the most worrisome possibilities in the field of antimutagenesis and anticarcinogenesis is that factors that protect against one mutagen or carcinogen will not be effective against another. Indeed, such specificities are known. Consequently, protective agents found in experimental screens and systems may not be relevant to the human situation. Additionally, the question of dose is also problematic, because factors that can protect against the levels of mutagens or carcinogens present in the human environment may be overwhelmed by the large dose of the agent used in the experiment, a dose necessitated by the need to have an effect against which protection can be judged. We suggest here that the new technologies available for the measurement of somatic mutation and chromosomal damage can be used to study spontaneous events, thus avoiding both problems.

Effect of maternal folate levels on somatic mutation frequency in the developing colon

Folic acid deficiency is associated with an increase in chromosomal aberrations in adult rodents and humans. Somatic mutations have a critical role in carcinogenesis. Since most mutations arise during early development, the effect of maternal folic acid levels on the spontaneous mutant frequency in the developing colon was examined using lacZ transgenic mice. No significant difference in mutant frequencies at both 3 and 8 weeks of age were found between offspring whose mothers were fed low folate and those on high folate diets during pregnancy. Our results suggest that the correlation between folic acid intake and cancer risk may only be effective at extreme folate deficiencies or in combination with other dietary deficiencies or an underlying predisposition.

Effect of mechanical ventilation strategy on dissemination of intratracheally instilled Escherichia coli in dogs

OBJECTIVE

To test the effect of different mechanical ventilation strategies on dissemination of intratracheally instilled Escherichia coli in dogs and to determine the extent and distribution of lung damage.

DESIGN

Prospective, randomized study.

SETTING

Experimental animal laboratory.

SUBJECTS

Eighteen anesthetized and paralyzed dogs.

INTERVENTIONS

We studied the effect of three ventilatory strategies based on two variables: transpulmonary pressure and positive end-expiratory pressure (PEEP). Group 1 animals (n = 6) were ventilated with a PEEP of 3 cm H2O and a tidal volume of 15 mL/kg, which generated an end-inspiratory transpulmonary pressure of < or = 15 cm H2O. In group 2(n = 6), tidal volume was adjusted to generate a transpulmonary pressure of 35 cm H2O and PEEP was set to 3 cm H2O. In group 3(n = 6), tidal volume was also adjusted to yield a transpulmonary pressure of 35 cm H2O but PEEP was set to 10 cm H2O. In each group, we instilled approximately 10(8) colony-forming units of E. coli into the trachea of the dogs and ventilated them with the chosen tidal volume and PEEP for 6 hrs afterward.

MEASUREMENTS AND MAIN RESULTS

We measured the pressure-volume relationship (pressure-volume curve) of the respiratory system before and 6 hrs after bacterial instillation. We obtained blood cultures before and 0.5, 1,2,3,4,5, and 6 hrs after bacterial instillation. After 6 hrs, the lungs were removed for histologic (histologic score) and gravimetric (wet-to-dry weight ratio, WW/DW) analysis. During the experiment 0, 5, and 1 dogs developed positive blood cultures in groups 1, 2, and 3, respectively. The number of dogs that developed bacteremia in group 2 was significantly greater than in the other two groups (p < .05). In group 1, pressure-volume curves demonstrated a lower inflection point which was greater than the end-inspiratory transpulmonary pressure suggesting that low transpulmonary pressure/low PEEP strategy ventilated aerated regions without expanding atelectatic areas. In group 2, pressure-volume curves demonstrated both a lower inflection point and an upper deflection point which were spanned by the tidal volume, suggesting that high transpulmonary pressure/low PEEP strategy might have caused both overdistention and cyclic closure and reopening. In group 3, pressure-volume curves demonstrated only a upper deflection point which was less than the maximal alveolar tidal pressure. At the end of the experimental protocol, group 2 manifested the most lung injury as assessed by gravimetric and histologic indices of lung injury. WW/DW of group 2(13.1 +/- 1.0 (SD); p < .05) was greater than groups 1 and 3(7.5 +/- 1.2 and 8.6 +/- 1.0, respectively). Similarly, the overall weighted histologic injury score for group 2 (1.19 +/- 0.26; p < .02) was greater than for groups 1 and 3 (0.82 +/- 0.20 and 0.88 +/- 0.22, respectively). For groups 2 and 3, the overall weighted histologic injury scores of the dependent regions were greater than the nondependent regions (p < .004).

CONCLUSIONS

We conclude that the ventilatory strategy most likely to overdistend the lungs while allowing repetitive opening and closure of alveoli (group 2) facilitated bacterial translocation from the alveoli to the bloodstream and increased lung injury, as determined by histologic and gravimetric analysis. PEEP ameliorated these effects, despite lung overdistention, but increased histologic and gravimetric indices of lung injury in dependent as compared with the nondependent regions.

Managers' attitudes towards mechanical aids

This article reports a study of the attitudes of NHS management and financial personnel to issues of moving and handling, in particular the use of mechanical aids. The study highlights some confusions about the responsibilities and roles of different personnel, and the authors make some recommendations to clarify these.