Reproductive factors, exogenous hormone use and risk of hepatocellular carcinoma among US women: results from the Liver Cancer Pooling Project.

BACKGROUND: Hepatocellular carcinoma (HCC) occurs less commonly among women than men in almost all regions of the world. The disparity in risk is particularly notable prior to menopause suggesting that hormonal exposures during reproductive life may be protective. Exogenous oestrogenic exposures such as oral contraceptives (OCs), however, have been reported to increase risk, suggesting that estrogens may be hepatocarcinogenic. To examine the effects of reproductive factors and exogenous hormones on risk, we conducted a prospective analysis among a large group of US women. METHODS: In the Liver Cancer Pooling Project, a consortium of US-based cohort studies, data from 799,500 women in 11 cohorts were pooled and harmonised. Cox proportional hazards regression models were used to generate hazard ratios (HRs) and 95% confidence intervals (CIs) for the associations of reproductive factors and exogenous hormones with HCC (n=248). RESULTS: Bilateral oophorectomy was associated with a significantly increased risk of HCC (HR=2.67, 95% CI=1.22-5.85), which did not appear to be related to a shorter duration of exposure to endogenous hormones or to menopausal hormone therapy use. There was no association between OC use and HCC (HR=1.12, 95% CI=0.82-1.55). Nor were there associations with parity, age at first birth, age at natural menopause, or duration of fertility. CONCLUSIONS: The current study suggests that bilateral oophorectomy increases the risk of HCC but the explanation for the association is unclear. There was no association between OC use and HCC risk. Examination of endogenous hormone levels in relation to HCC may help to clarify the findings of the current study.

Experimental identification of diffusive coupling using 2D NMR.

Spin relaxation based nuclear magnetic resonance (NMR) methods have been used extensively to determine pore size distributions in a variety of materials. This approach is based on the assumption that each pore is in the fast diffusion limit but that diffusion between pores can be neglected. However, in complex materials these assumptions may be violated and the relaxation time distribution is not easily interpreted. We present a 2D NMR technique and an associated data analysis that allow us to work directly with the time dependent experimental data without Laplace inversion to identify the signature of diffusive coupling between different pores. Measurements on microporous glass beads and numerical simulations are used to illustrate the technique.

Modeling two-dimensional magnetic resonance measurements in coupled pore systems.

We present numerical simulations of a two-dimensional (2D) nuclear magnetic resonance process, T_{2}-storage-T_{2}, on a simple mixed porosity system, the micrograin consolidation (µGC) model. The results of these calculations are compared with predictions based on the analytic two-site exchange model, for which we have independently established numerical values for all the input parameters. Although there is qualitative and semiquantitative agreement between the two models, we identify specific instances where the two-site model fails to properly describe the combined effects of relaxation and diffusion. Generally, these instances occur when a gradient in magnetization within the large pores of the µGC model is established during the initial phase of the 2D process. The two-site model assumes that the magnetization is spatially uniform within each of its subpore systems and thus cannot describe such effects.

Atrophy and programmed cell death of skeletal muscle.

Striated skeletal is subject to nonlethal cycles of atrophy in response to a variety of physiological and pathological stimuli, including: starvation, disuse, denervation and inflammation. These cells can also undergo cell death in response to appropriate developmental signals or specific pathological insults. Most of the insights gained into the control of vertebrate skeletal muscle atrophy and death have resulted from experimental interventions rather than natural processes. In contrast, the intersegmental muscles (ISMs) of moths are giant cells that initiate sequential and distinct programs of atrophy and death at the end of metamorphosis as a normal component of development. This model has provided fundamental information about the control, biochemistry, molecular biology and anatomy of naturally occurring atrophy and death in vivo. The ISMs have provided a good complement to studies in vertebrates and may provide insights into clinically relevant disorders.

Induction of Anoikis following myoblast transplantation into SCID mouse muscles requires the Bit1 and FADD pathways.

Seventy-five percent of the myoblasts transplanted in the mouse muscle die during the first 4 days following transplantation. The purpose of this study was to determine if anoikis plays a role in this phenomenon. Survival and proliferation of myoblasts in vitro were determined by Hoescht-PI labeling and cell counts respectively. In vivo cell survival and proliferation were quantified by injecting human male myoblasts labeled with (14)C-thymidine in SCID mouse muscles. Survival and proliferation of the transplanted myoblasts were evaluated by scintigraphy and quantitative PCR of human Y chromosomal DNA. Inclusion of the extracellular matrix protein fibronectin enhanced transplanted myoblast survival by 1.7-fold while vitronectin improved their proliferation by 1.8-fold. Reductions in FADD and Bit1 expression reduced anoikis in vitro and improved the injected myoblast survival in vivo. Ectopic expression of the anti-apoptotic protein Bcl-2 completely abolished myoblast anoikis in vitro and enhanced cell survival by 3.1-fold in vivo. Cell death following transplantation appears to me mediated in part by anoikis. Inclusion of extracellular matrix proteins enhanced both survival and proliferation. Reduced expression of the proapoptotic proteins Bit1 and FADD or overexpression of Bcl-2 improved myoblast survival.

Post-transcriptional regulation of gene expression during the programmed death of insect skeletal muscle.

While considerable attention has focused on the role of specific proteins in mediating programmed cell death, few studies have examined the possible involvement of post-transcriptional regulation of mRNAs associated with this developmental process. We have examined developmental changes in transcript stability and translatability using protein extracts generated from the intersegmental muscles (ISM) of the moth Manduca sexta as a cell-free model system to examine three genes that are representative of the patterns of expression observed in condemned ISMs: repressed (actin), induced (polyubiquitin) and constitutively expressed (ubiquitin-fusion 80; ubf80). In addition, we have used luciferase mRNA as a generic reporter transcript to determine if there are sequence-specific controls of mRNA function related to programmed cell death. Among the three Manduca transcripts, polyubiquitin displayed the shortest half-life (t1/2) in all ISM extracts tested. The stability and translatability of all mRNAs were most affected in extracts from muscle cells from day 17 animals, just prior to the commitment of the muscles to die. Transfer of the 3' untranslated regions from the Manduca transcripts to luciferase mRNA did not appreciably change the stability or translatability of this test transcript. These data suggest that there may be global removal of cellular transcripts just prior to death to allow newly expressed mRNAs to rapidly accumulate to high levels. Such changes in message abundance, translatability and stability may facilitate the efficient activation of death (and perhaps other differentiation programs) in some developmental systems.

Direct-to-consumer advertisements for prescription drugs: what are Americans being sold?

BACKGROUND: Pharmaceutical companies spent US$1.8 billion on direct-to-consumer advertisements for prescription drugs in 1999. Our aim was to establish what messages are being communicated to the public by these advertisements. METHODS: We investigated the content of advertisements, which appeared in ten magazines in the USA. We examined seven issues of each of these published between July, 1998, and July, 1999. FINDINGS: 67 advertisements appeared a total of 211 times during our study. Of these, 133 (63%) were for drugs to ameliorate symptoms, 54 (26%) to treat disease, and 23 (11%) to prevent illness. In the 67 unique advertisements, promotional techniques used included emotional appeals (45, 67%) and encouragement of consumers to consider medical causes for their experiences (26, 39%). More advertisements described the benefit of medication with vague, qualitative terms (58, 87%), than with data (9, 13%). However, half the advertisements used data to describe side-effects, typically with lists of side-effects that generally occurred infrequently. None mentioned cost. INTERPRETATION: Provision of complete information about the benefit of prescription drugs in advertisements would serve the interests of physicians and the public.

Duration and reinstatement of myocardial protection against infarction by ischemic preconditioning in open chest dogs.

These studies were undertaken to determine the duration of protection against myocardial infarction provided by ischemic preconditioning in the canine heart, and to learn if cardioprotection can be restored by another preconditioning stimulus when the initial effect is lost. Control and four preconditioning groups of anesthetized, open-chest dogs were compared. All underwent a test 60 min episode of ischemia, induced by occlusion of the anterior descending (LAD) artery, followed by 3 h of reperfusion. Preconditioning was induced by one 10 min LAD occlusion, followed by either 10 min, 2, 3, or 5 h of reperfusion. In order to test whether preconditioning could be reinstated, another group of dogs with preconditioning plus 3 h reperfusion underwent a second 10 min preconditioning stimulus with 10 min reperfusion before the 60 min test-occlusion. Infarct size (as percent of area-at-risk) was analyzed (using analysis of covariance) with respect to coronary collateral blood flow measured with radioactive microspheres. Infarct size was limited markedly by preconditioning (23+/-6 v 6+/-2%, P<0.05) but the protective effect was dissipated partially after 2 h reperfusion and was dissipated completely after 3 h reperfusion (20+/-4%, non-significant v Control and significant P<0.05 v preconditioning). Protection was restored in three of six dogs with preconditioning +5 h reperfusion, suggesting that the second window of protection appears early in some canine hearts. When preconditioning was repeated after 3 h reperfusion, cardioprotection was reinstated fully (7+/-2%, P<0.05 v Control and NS v preconditioning). The results show that maximal preconditioning cardioprotection is present in the dog heart after 10 min of reperfusion and is dissipated totally following 3 h of reperfusion. However, a second preconditioning stimulus of 10 min of ischemia followed by 10 min of reperfusion to the dissipated preconditioned heart reinstates full preconditioning. Thus, this model provides a system to test for theoretical causes of the preconditioned state. Final mediators should be present when preconditioning is present and absent when preconditioning is dissipated. It is noteworthy that a second window of protection appeared in 50% of dogs when the period of reperfusion was extended to 5 h.

Metabolism of preconditioned myocardium: effect of loss and reinstatement of cardioprotection.

Ischemic preconditioning is associated with slower destruction of the adenine nucleotide pool and a slower rate of anaerobic glycolysis during subsequent ischemic stress. Whether this association is causal is uncertain. Using metabolite levels found at baseline and after a 15 min test episode of ischemia, this study tested for concordance, or lack thereof, between the presence or absence of metabolic features v the presence or absence of the preconditioned state. Dogs were assigned to one of four groups: non-preconditioned control (C), full preconditioning (PC) caused by 10 min ischemia (I)+10 min reperfusion (R), dissipated PC (DPC) caused by 10 min I and 180 min R, or reinstated PC in which PC was reinstated in DPC hearts by another 10 min I and 10 min R. At baseline, PC and RPC hearts had a 25% or more decrease in the adenine nucleotide pool (summation operatorAd), a substantial creatine phosphate (CP) overshoot, and a 4-6 times elevation in tissue glucose (G). Of these changes, the decreased summation operatorAd and the CP overshoot persisted during DPC, whereas only G returned to control. Thus, increased G was the only baseline feature, which was concordant with the preconditioned state. The response to ischemic stress in PC and RPC tissue included less lactate production and much less degradation of the summation operatorAd pool to nucleosides and bases than in the C or DPC groups. Thus, slower destruction of the summation operatorAd pool and slower lactate production during ischemia also were concordant with the PC state. The results support the hypothesis that a reduction in energy demand is an essential component of the mechanism of cardioprotection in preconditioned myocardium. However, the mechanism through which ischemic preconditioning results in lower energy demand remains to be established.

Assessing values for health: numeracy matters.

BACKGROUND: Patients' values are fundamental to decision models, cost-effectiveness analyses, and pharmacoeconomic analyses. The standard methods used to assess how patients value different health states are inherently quantitative. People without strong quantitative skills (i.e., low numeracy) may not be able to complete these tasks in a meaningful way. METHODS: To determine whether the validity of utility assessments depends on the respondent's level of numeracy, the authors conducted in-person interviews and written surveys and assessed utility for the current health for 96 women volunteers. Numeracy was measured using a previously validated 3-item scale. The authors examined the correlation between self-reported health and utility for current health (assessed using the standard gamble, time trade-off, and visual analog techniques) across levels of numeracy. For half of the women, the authors also assessed standard gamble utility for 3 imagined health states (breast cancer, heart disease, and osteoporosis) and asked how much the women feared each disease. RESULTS: Respondent ages ranged from 50 to 79 years (mean = 63), all were high school graduates, and 52% had a college or postgraduate degree. Twenty-six percent answered 0 or only 1 of the numeracy questions correctly, 37% answered 2 correctly, and 37% answered all 3 correctly. Among women with the lowest level of numeracy, the correlation between utility for current health and self-reported health was in the wrong direction (i.e., worse health valued higher than better health): for standard gamble, Spearman r=-0.16, P = 0.44;for time trade-off, Spearman r=-0.13, P=0.54. Among the most numerate women, the authors observed a fair to moderate positive correlation with both standard gamble (Spearman r=0.22, P=0.19) and time trade-off (Spearman r=0.50, P=0.002). In contrast, using the visual analog scale, the authors observed a substantial correlation in the expected direction at all levels of numeracy (Spearman r= 0.82, 0.50, and 0.60 for women answering 0-1, 2, and 3 numeracy questions, respectively; all Ps < or = 0.003). With regard to the imagined health states, the most feared disease had the lowest utility for 35% of the women with the lowest numeracy compared to 76% of the women with the highest numeracy (P=0.03). CONCLUSIONS: The validity of standard utility assessments is related to the subject's facility with numbers. Limited numeracy may be an important barrier to meaningfully assessing patients' values using the standard gamble and time trade-off techniques.

Tortuosity measurement and the effects of finite pulse widths on xenon gas diffusion NMR studies of porous media.

We have extended the utility of NMR as a technique to probe porous media structure over length scales of approximately 100-2000 microm by using the spin 1/2 noble gas 129Xe imbibed into the system's pore space. Such length scales are much greater than can be probed with NMR diffusion studies of water-saturated porous media. We utilized Pulsed Gradient Spin Echo NMR measurements of the time-dependent diffusion coefficient, D(t), of the xenon gas filling the pore space to study further the measurements of both the pore surface-area-to-volume ratio, S/V(p), and the tortuosity (pore connectivity) of the medium. In uniform-size glass bead packs, we observed D(t) decreasing with increasing t, reaching an observed asymptote of approximately 0.62-0.65D(0), that could be measured over diffusion distances extending over multiple bead diameters. Measurements of D(t)/D(0) at differing gas pressures showed this tortuosity limit was not affected by changing the characteristic diffusion length of the spins during the diffusion encoding gradient pulse. This was not the case at the short time limit, where D(t)/D(0) was noticeably affected by the gas pressure in the sample. Increasing the gas pressure, and hence reducing D(0) and the diffusion during the gradient pulse served to reduce the previously observed deviation of D(t)/D(0) from the S/V(p) relation. The Pade approximation is used to interpolate between the long and short time limits in D(t). While the short time D(t) points lay above the interpolation line in the case of small beads, due to diffusion during the gradient pulse on the order of the pore size, it was also noted that the experimental D(t) data fell below the Pade line in the case of large beads, most likely due to finite size effects.

Not all muscles meet the same fate when they die.

Two general patterns of cell death are usually described in animals: necrosis and apoptosis. The former is a passive process that displays cellular swelling and lysis, while the latter involves cellular shrinkage and gene-mediated, ATP-dependent processes. Independent of the proximal cause of cell death, cell corpses are almost always removed by phagocytic cells. This is far from universal for all cells however, since phagocytic cells have not been noted during the programmed death of some skeletal muscles in insects. To further explore this, we used a variety of anatomical methods to examine the death of the intersegmental muscles (ISMs) of the moth Manduca sexta. The ISMs are giant cells that die during the 30 h following adult emergence. At no stage examined were hemocytes or other cells associated with the sarcolemma. The failure to detect macrophages was not due to technical limitations since immunohistochemical and functional studies demonstrate their presence in the hemolymph. The absence of phagocytosis to remove ISM corpses suggests that all of the biochemical machinery required for cellular destruction is resident within the ISMs themselves. This is consistent with analysis suggesting that Manduca does not possess sufficient numbers of macrophages to consume the ISMs. Given that insects do not have adaptive immunity, the ability to use a completely cell autonomous process may be a developmental option that cannot be exploited in vertebrates.

Women's views on breast cancer risk and screening mammography: a qualitative interview study.

BACKGROUND: To promote informed decision making about mammography, clinicians are urged to present women with complete, relevant information about breast cancer and screening. Understanding women's current beliefs may help guide such efforts by uncovering misunderstandings, conceptual gaps, and areas of concern. OBJECTIVE: The authors sought to learn how women view breast cancer, their personal risk of breast cancer, and how screening mammography affects that risk. METHODS: Forty-one open-ended semistructured telephone interviews with women selected from a national database by quota sampling to ensure a wide range in demographics of the participants. RESULTS: Almost all respondents viewed breast cancer as a uniformly progressive disease that begins in a silent curable form (typically found by mammograms) and, unless treated early, invariably grows, spreads, and kills. Some women felt that any abnormality found must be treated, even if it was not malignant. None had heard of potentially nonprogressive cancers, and when informed, most felt that the uncertain prognosis of such lesions reinforced the need to find and treat disease as soon as possible. Women expressed a wide range of views about their personal risk of breast cancer. Although some saw breast cancer as a central threat to their health, many others cited heart disease, other cancers, violence, and trauma as greater concerns. Most recognized the importance of "uncontrollable" factors for breast cancer such as age, sex, family history, and genetics. However, other "controllable" factors with little or no demonstrated link to breast cancer (e.g., smoking, diet, toxic exposures, "bad attitudes") were given equal or greater prominence, suggesting that many women feel considerable personal responsibility for their level of breast cancer risk. Similarly, although women recognized that mammography was not perfect, almost all believed that failure to have mammograms put one at risk for premature and preventable death. When asked how mammography worked, almost all repeated the message that "early detection saves lives," suggesting that advanced cancer (and perhaps most cancer deaths) reflected a failure of early detection. The belief in the benefit of early detection was so strong that some women advocated scaring other women into getting mammograms because it is "better to be safe than sorry." CONCLUSIONS: Women view breast cancer as a uniformly progressive disease rarely curable unless caught early. The exaggerated importance many attribute to a variety of controllable factors in modifying personal risk and the "danger" seen in failing to have mammograms may lead women diagnosed with breast cancer to blame themselves.

The RHG motifs of Drosophila Reaper and Grim are important for their distinct cell death-inducing abilities.

Reaper, Hid, and Grim are three Drosophila cell death activators that each contain a conserved NH(2)-terminal Reaper, Hid, Grim (RHG) motif. We have analyzed the importance of the RHG motifs in Reaper and Grim for their different abilities to activate cell death during development. Analysis of chimeric R/Grim and G/Reaper proteins indicated that the Reaper and Grim RHG motifs are functionally distinct and help to determine specific cell death activation properties. A truncated GrimC protein lacking the RHG motif retained an ability to induce cell death, and unlike Grim, R/Grim, or G/Reaper, its actions were not efficiently blocked by the cell death inhibitors, Diap1, Diap2, p35, or a dominant/negative Dronc caspase. Finally, we identified a second region of sequence similarity in Reaper, Hid, and Grim, that may be important for shared RHG motif-independent activities.

US women's attitudes to false-positive mammography results and detection of ductal carcinoma in situ: cross-sectional survey.

OBJECTIVE: To determine women's attitudes and knowledge of both false-positive mammography results and the detection of ductal carcinoma in situ after screening mammography. DESIGN: Cross-sectional survey. SETTING: United States. PARTICIPANTS: A total of 479 women aged 18 to 97 years who did not report a history of breast cancer. Main outcome measures Attitudes and knowledge about false-positive results and the detection of ductal carcinoma in situ after screening mammography. RESULTS: Women were aware that false-positive results do occur. Their median estimate of the false-positive rate for 10 years of annual screening was 20% (25th percentile estimate, 10%; 75th percentile estimate, 45%). The women were highly tolerant of false-positive results: 63% thought that 500 or more false-positives per life saved was reasonable, and 37% would tolerate a rate of 10,000 or more. Women who had had a false-positive result (n = 76) expressed the same high tolerance: 30 (39%) would tolerate 10,000 or more false-positives. In all, 62% of women did not want to take false-positive results into account when deciding about screening. Only 8% of women thought that mammography could harm a woman without breast cancer, and 94% doubted the possibility of nonprogressive breast cancers. Few had heard of ductal carcinoma in situ, a cancer that may not progress, but when informed, 60% of women wanted to take into account the possibility of it being detected when deciding about screening. CONCLUSIONS: Women are aware of false-positive results and seem to view them as an acceptable consequence of screening mammography. In contrast, most women are unaware that screening can detect cancers that may never progress but think that such information would be relevant. Education should perhaps focus less on false-positive results and more on the less-familiar outcome of the detection of ductal carcinoma in situ.