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After treatment at a microsomal nuclease concentration too low to reduce the endogenous amino acid-incorporating activity of freshly prepared reticulocyte lysate, there is little, if any, intact 26 S RNA left in the ribosomes of either wheat germ or rabbit reticulocyte cell-free protein synthesizing extracts. The primary scissions, probably at highly exposed sites in the rRNA of plant and animal ribosomes, produce two fragments which remain complexed until thermal denaturation reveals "hidden breaks." Molecular weights of the fragments are approximately 0.5 x 10(6) and 0.8 x 10(6) in the case of wheat, and 0.4 x 10(6) and 1.3 x 10(6) in the case of rabbit. There is little perceptible degradation of 5 S, 5.8 S, and 18 S rRNA, or of tRNA in the same extracts. Even though limited degradation of 26 S rRNA by a reticulocyte nuclease has been reported to severely impair the translational mechanism in reticulocyte ribosomes, micrococcal nuclease-induced degradation of rRNA, whether limited or extensive, does not seriously impair the ability of reticulocyte lysates to discriminate, by selective polypeptide synthesis, between complex populations of cellular mRNA. In an allied study, it is shown that under conditions well suited to recovery of the 5.8 S/26 S rRNA complex, with its naturally occurring hidden break, 5 S/18 S rRNA complexing is not detectable in the RNA or metabolizing embryos, nor in the RNA from untreated or nuclease-treated protein synthesizing extracts from wheat and rabbit. The significance of this finding is briefly elaborated in relation to the suggestion that 5 S rRNA may interact with the M2(6)A-m2(6)A hairpin near the 3'-end of 18 S rRNA.
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Eight hundred seventy patients with metastatic nonseminomatous germ cell cancer underwent postchemotherapy retroperitoneal lymph node dissection (PC-RPLND) for resection of residual disease. Several risk factors for relapse and survival were identified as highly significant (P = .00001), namely, presence of residual cancer in the specimen before salvage chemotherapy programs, tumor marker elevation, need for "re-do" PC-RPLND, or unresectability. Although more than half of the entire group (52.5%) had one or more of these risk factors, 67.5% are long-term survivors following PC-RPLND. The remaining 47.5% were referred after primary chemotherapy, without risk factors. Only 9.8% relapsed and 95.5% survived.
Employer pensions that integrate benefits with Social Security have been the focus of relatively little research. Since changes in Social Security benefit levels and other program characteristics can affect the benefit levels and other features of integrated pension plans, it is important to know who is covered by these plans. This article examines the characteristics of workers covered by integrated pension plans, compared to those with nonintegrated plans and those with no pension coverage. Integrated pension plans are those that explicitly adjust their benefit structure to help compensate for the employer's contributions to the Social Security program. There are two basic integration methods used by defined benefit (DB) plans. The offset method causes a reduction in employer pension benefits by up to half of the Social Security retirement benefit; the excess rate method is characterized by an accrual rate that is lower for earnings below the Social Security taxable maximum than above it. Defined contribution (DC) pension plans can be integrated along the lines of the excess rate method. To date, research on integrated pensions has focused on plan characteristics, as reported to the Bureau of Labor Statistics (BLS) through its Employee Benefits Survey (EBS). This research has examined the prevalence of integration among full-time, private sector workers by industry, firm size, and broad occupational categories. However, because the EBS provides virtually no data on worker characteristics, analyses of the effects of pension integration on retirement benefits have used hypothetical workers, varying according to assumed levels of earnings and job tenure. This kind of analysis is not particularly helpful in examining the potential effects of changes in the Social Security program on workers' pension benefits. However, data on pension integration at the individual level are available, most recently from the Health and Retirement Study (HRS), a nationally representative survey of individuals aged 51-61 in 1992. This dataset provides the basis for the analysis presented here. The following are some of the major findings from this analysis. The incidence of pension integration in the HRS sample is 32 percent of all workers with a pension (14 percent of all workers). The HRS can also identify integrated DC plans, a statistic that is not available from BLS data. The rate of integration for workers with only DC plans is 8 percent. After controlling for other variables, several socio-demographic characteristics are significantly related to the incidence of integration. The probability of having an integrated pension is 4.6 percentage points less for men compared to women. Non-Hispanic blacks are 6.4 percentage points less likely than non-Hispanic whites to have integrated pensions. Union members are 14 percentage points less likely to have integrated pensions, while workers with less than a graduate level education are at least 15 percentage points more likely to have a pension that is integrated. Some earnings and pension characteristics are also significantly correlated with pension integration. Earnings are positively related, with the probability of having an integrated pension increasing by 2 percentage points for an increase of $1,000 in annual pay. An even larger effect comes from earning at or above the Social Security taxable maximum. Workers at or above this income level are 10 percentage points more likely to have an integrated plan, but for those with more than one plan the probability of pension integration goes up by 13 percentage points.
The development of invasive cervical cancer is associated with human papillomavirus (HPV) infection and subsequent integration into the host epithelium. More than 99% of cervical cancers contain HPV sequences, and many of these contain a truncated HPV genome integrated into a single position within the host genome. Studies examining the role of viral integration in cervical cancer development have found that the sites of integration appear randomly distributed throughout the genome. This, and the observation that it frequently takes years after HPV infection for cervical cancer to develop, has led to the current paradigm that the site of HPV integrations is unimportant to the invasive cervical cancer that eventually develops. In our previous studies of HPV16 and HPV18 integration in cervical cancers, we also found integrations throughout the genome, but observed as well that more than half of the integrations occurred within common fragile site regions. To determine if HPV integration might play an important role in cervical cancer, we conducted two complementary studies. We first localized 40 new HPV16 integration sites from cervical tumors from women in Hong Kong; this, together with previous integration studies, provided a better picture of the distribution of integration sites throughout the genome. We then analyzed the sites of viral integration in an in vitro model of HPV integration. By comparing the sites of HPV integration in vivo (in multiple primary cervical tumors) to those obtained in vitro, the data can help to determine if HPV integrations observed in vivo are the result of random and nonselected integrations.