Pituitary tumors in mice after prolonged feeding of synthetic progestins

An enhanced development of pituitary tumors was observed in virgin female mice of the C57 Leaden strain following repeated oral administration of synthetic progestins. This finding appears to parallel the co-carcinogenic enhancement of mammary tumor development elicited in C3H mice treated repeatedly with progesterone.     

Antiserum to lymphocytes: prolonged survival of canine renal allografts

A horse immunized with dog lynmphocytes produced an antiserum which agglutinated canine lymphocytes in vitro and caused prolonged lymphopenia in dogs in vivo. Renal transplants in dogs treated with this antiserum survived for long periods, two of the grafts surviving beyond 350 days with normal function and histologic appearance.     

Planetary albedo changes due to aerosols

Absorption and scattering by aerosols and reflection of solar radiation from the surface determine the sign of the change in the planetary albedo caused by the presence of aerosols. This change in planetary albedo results in atmospheric heating or cooling. Small changes in the ratio of absorption to scattering over time can reverse such heating or cooling trends.     

Arctic ozone loss due to denitrification

Measurements from the winter of 1994-95 indicating removal of total reactive nitrogen from the Arctic stratosphere by particle sedimentation were used to constrain a microphysical model. The model suggests that denitrification is caused predominantly by nitric acid trihydrate particles in small number densities. The denitrification is shown to increase Arctic ozone loss substantially. Sensitivity studies indicate that the Arctic stratosphere is currently at a threshold of denitrification. This implies that future stratospheric cooling, induced by an increase in the anthropogenic carbon dioxide burden, is likely to enhance denitrification and to delay until late in the next century the return of Arctic stratospheric ozone to preindustrial values.     

Climatic fluctuations due to deep ocean circulation

A simple climate model that includes the effect of deep ocean turnover as a pure time delay exhibits an oscillatory behavior. The deep ocean signal contains frequencies characteristic of both the forcing function and the deep ocean delay.     

免疫检查点抑制剂的内分泌毒性

免疫检查点抑制剂的应用标志着肿瘤治疗的重大进步,其机制是通过解除免疫抑制、活化T细胞功能增强免疫,提高对肿瘤细胞的杀伤作用;然而,活化T细胞会增加自身抗体及细胞因子,从而攻击人体正常组织,产生一系列免疫相关性不良事件,如皮肤、胃肠道、肝脏、内分泌、骨骼肌肉毒性等.该文综述了免疫检查点抑制剂所致的内分泌毒性.     

Limitations on space flight due to cosmic radiations

These conclusions (10) may be summarized as follows: 1) Flight below the Van Allen belts seems reasonably safe without radiation shielding. 2) It is probably impractical to shield a rocket sufficiently to permit a man to remain in the inner Van Allen belt for more than about an hour, but it should be possible for him to go through it without serious harm. 3) Shielding for the outer Van Allen belt is possible but would have to be quite heavy if a stay of more than a few hours were contemplated. 4) The primary cosmic radiation is not intense enough to deliver a serious radiation dose, even for exposures of a few weeks, and the heavy cosmic ray primaries do not seem to present an unusual hazard.     

Fatal disease of swine due to encephalomyocarditis virus

Encephalomyocarditis virus was isolated from the organs of swine dying during an outbreak of an acutely fatal disease occurring on a farm in Panama. The outstanding lesion was severe myocarditis. Pigs inoculated with the viral isolate developed a systemic infection with myocarditis.     

Inland ice sheet thinning due to holocene warmth

The climatic warming of 10,000 years ago is now affecting the central portions of ice sheets, causing ice-flow acceleration. This process explains the present-day thinning of the ice sheet in West Antarctica. Former ice sheets must have also responded to climatic warming with a delay of thousands of years. This lag in response is important in the climatic interpretation of glacial deposits and of changes in ice volume obtained from deep-sea cores.     

Detecting Climate Change due to Increasing Carbon Dioxide

The observed interannual variability of temperature at 60 degrees N has been investigated. The results indicate that the surface warming due to increased carbon dioxide which is predicted by three-dimensional climate models should be detectable now. It is not, possibly because the predicted warming is being delayed more than a decade by ocean thermal inertia, or because there is a compensating cooling due to other factors. Further consideration of the uncertainties in model predictions and of the likely delays introduced by ocean thermal inertia extends the range of time for the detection of warming, if it occurs, to the year 2000. The effects of increasing carbon dioxide should be looked for in several variables simultaneously in order to minimize the ambiguities that could result from unrecognized compensating cooling.     

Central nervous system dysfunction due to lead exposure

Central nervous system dysfunction was investigated in workers at a secondary lead smelter by means of performance tests. Correlations between test scores and zinc protoporphyrin levels, a biological indicator of lead toxicity, are statistically significant. This correlation should prove to be useful in current efforts to evaluate effects of lead exposure.     

HIV with reduced sensitivity to zidovudine (AZT) isolated during prolonged therapy

The drug sensitivities of human immunodeficiency virus (HIV) isolates from a group of patients with acquired immunodeficiency syndrome (AIDS) or AIDS-related complex (ARC) who were receiving zidovudine (3'-azido-3'-deoythymidine, AZT) therapy were tested by means of a newly developed plaque assay in CD4+ HeLa cells. Fifty percent inhibitory dose (ID50) values of 18 isolates from untreated individuals ranged between 0.01 microM and 0.05 microM. In contrast, most isolates from patients who had received zidovudine for 6 months or more exhibited decreased sensitivity characterized by changes in ID50 or ID95 values (or both), with isolates from several patients (5/15) showing 100-fold increases in ID50. The latter isolates were also insensitive to 3'-azido-2',3'-dideoxyuridine; however, the isolates were still sensitive to 2',3'-dideoxycytidine, 2',3'-dideoxy-2',3'-didehydrothymidine, or phosphonoformate. It cannot be determined from this small sample of patients whether development of a less sensitive virus phenotype results in clinical resistance. Appearance of such variants was not associated with a consistent increase in viral p24 concentrations in patient plasma and did not herald any sudden deterioration in clinical status. More extensive studies are required to determine the clinical significance. Thus, it would be premature to alter any treatment protocols for HIV-infected individuals at present.     

From red to green: Cuba forced to conserve due to economic crisis

The most severe economic crisis in post-revolutionary Cuba has forced the country to adopt an austere conservation program. Resource-wise measures have been instituted in the energy, transportation, housing, and agricultural sectors because of a rapid drop in Soviet aid, significant loss of trade with the Eastern Bloc, a halving of oil imports in a one-year period, and stepped-up U. S. sanctions. The economic crisis is also causing negative environmental impacts, in part because pollution abatement projects have been deferred and the tourism industry is being developed to bring in hard currency. However, it is anticipated that many environmentally-sound initiatives will help Cuba through the crisis and will remain in place.     

Immunologic manipulation of metastases due to herpesvirus transformed cells

Herpes simplex virus type 1 (HSV-1), type 2 (HSV-2), and simian virus 40 (SV40) fail to induce immunity in weanling Syrian hamsters to transplant of hamster cells transformed by HSV-2. However, the development of metastatic tumors is markedly enhanced by prior immunization with HSV-1. Immunization with SV40, ultraviolet-irradiated tumor cells, or ultraviolet-irradiated normal hamster embryo cells inhibits the development of metastases. The HSV-hamster system appears a good one for the study of development, prevention, and control of metastases by mammalian cells transformed by a common human virus.     

Greenhouse Effects due to Man-Mad Perturbations of Trace Gases

Nitrous oxide, methane, ammonia, and a number of other trace constituents in the earth's atmosphere have infrared absorption bands in the spectral region 7 to 14 microm and contribute to the atmospheric greenhouse effect. The concentrations of these trace gases may undergo substantial changes because of man's activities. Extensive use of chemical fertilizers and combustion of fossil fuels may perturb the nitrogen cycle, leading to increases in atmospheric N(2)O, and the same perturbing processes may increase the amounts of atmospheric CH(4) and NH(3). We use a one-dimensional radiative-convective model for the atmospheric thermal structure to compute the change in the surface temperature of the earth for large assumed increases in the trace gas concentrations; doubling the N(2)O, CH(4), and NH(3) concentrations is found to cause additive increases in the surface temperature of 0.7 degrees , 0.3 degrees , and 0.1 degrees K, respectively. These systematic effects on the earth's radiation budget would have substantial climatic significance. It is therefore important that the abundances of these trace gases be accurately monitored to determine the actual trends of their concentrations.     

苦瓜因土施肥技术规程

在进行几年以苦瓜为代表的瓜类蔬菜营养施肥田间试验研究、建立了苦瓜测土施肥技术指标体系的基础上,为促进蔬菜产业向规模化、标准化发展,实现蔬菜生产的规范化施肥,制订了苦瓜因土施肥技术规程,系统概述了以苦瓜为代表的瓜类蔬菜生产的土壤管理和施肥技术措施,包括产地环境、施肥要求、因土施肥的量化操作技术。