Indirect standardization for rare events and a dynamic standard population rate: An analysis and simulation of U.S. military suicide mortality rates.

INTRODUCTION: Comparing suicide mortality rates between the U.S. military and U.S. general populations is common in lay and professional literature. Standardization is required for this comparison to account for differences in the population structure, but small event counts complicate the analysis. METHODS: We demonstrated the performance of direct, indirect, and reverse-direct standardization using U.S. military and U.S. general population suicide mortality data from 2011 to 2018. We also used simulations of direct and indirect standardization in annual comparisons, and over time for the standardized mortality ratio in Poisson regression. RESULTS: Indirect standardization outperformed direct standardization for annual rate standardization. Direct standardization with combined subgroups can produce a biased estimate. Reverse-direct standardization was unbiased, but it generally yields incorrect interval estimates. Over 2011-2018, the U.S. military suicide mortality data were very consistent with the U.S. general population. CONCLUSION: Indirect standardization provides more flexibility in rate standardization with rare outcomes. For comparisons between the U.S. military and the U.S. general populations, it can provide valid point and interval estimates of standardized rates and ratios both within a single year and between years without combining categories to account for sparseness.

Jupiter's atmospheric composition from the Cassini thermal infrared spectroscopy experiment.

The Composite Infrared Spectrometer observed Jupiter in the thermal infrared during the swing-by of the Cassini spacecraft. Results include the detection of two new stratospheric species, the methyl radical and diacetylene, gaseous species present in the north and south auroral infrared hot spots; determination of the variations with latitude of acetylene and ethane, the latter a tracer of atmospheric motion; observations of unexpected spatial distributions of carbon dioxide and hydrogen cyanide, both considered to be products of comet Shoemaker-Levy 9 impacts; characterization of the morphology of the auroral infrared hot spot acetylene emission; and a new evaluation of the energetics of the northern auroral infrared hot spot.

An intense stratospheric jet on Jupiter.

The Earth's equatorial stratosphere shows oscillations in which the east-west winds reverse direction and the temperatures change cyclically with a period of about two years. This phenomenon, called the quasi-biennial oscillation, also affects the dynamics of the mid- and high-latitude stratosphere and weather in the lower atmosphere. Ground-based observations have suggested that similar temperature oscillations (with a 4-5-yr cycle) occur on Jupiter, but these data suffer from poor vertical resolution and Jupiter's stratospheric wind velocities have not yet been determined. Here we report maps of temperatures and winds with high spatial resolution, obtained from spacecraft measurements of infrared spectra of Jupiter's stratosphere. We find an intense, high-altitude equatorial jet with a speed of approximately 140 m s(-1), whose spatial structure resembles that of a quasi-quadrennial oscillation. Wave activity in the stratosphere also appears analogous to that occurring on Earth. A strong interaction between Jupiter and its plasma environment produces hot spots in its upper atmosphere and stratosphere near its poles, and the temperature maps define the penetration of the hot spots into the stratosphere.

Pharmacological effect of nitroprusside on platelet aggregation.

Adequate platelet function and numbers are critical for postcardiopulmonary bypass patients. Endogenous and pharmacological sources of nitric oxide (NO) are known inhibitors of platelet aggregation. Sodium nitroprusside (SNP), used clinically to control blood pressure, is an inorganic source of NO. Our long-term goal is to determine if SNP infusion in the venous return line of the cardiopulmonary bypass system would preserve platelet numbers and function without affecting systemic vascular resistance. Our first requirement to accomplish this goal was to develop an assay that would detect the SNP effect on platelet aggregation. We, therefore, tested the hypothesis that clinical concentrations of SNP would inhibit platelet aggregation. We quantified platelet aggregation with the Medtronic Hepcon HMS whole blood aggregometer. Normal heparinized human blood was treated with 0.625 to 12.5 nM platelet activating factor (PAF), 0.25 to 5.0 microM epinephrine, or 0.20 to 10 microM adenosine 5'-diphosphate (ADP) to stimulate platelet aggregation. SNP was added at 10(-5) M to determine its affect on PAF, epinephrine, and ADP stimulated platelet aggregation. The results demonstrated that PAF-stimulated platelet aggregation was significantly inhibited with SNP (10(-5) M) to 82% (p < .05) of control and epinephrine and ADP mediated aggregation were not significantly affected. In conclusion, at clinically relevant concentrations SNP inhibits platelet aggregation by PAF but not with ADP or epinephrine.

Human thymocytes express a prolactin-like messenger ribonucleic acid and synthesize bioactive prolactin-like proteins.

Recent evidence has demonstrated an important immunoregulatory role for pituitary PRL. Moreover, PRLs have been identified as products of transformed human lymphocyte cell lines and normal murine lymphocytes, and implicated as regulators of their proliferative responses. However, PRL synthesis by normal human lymphocytes has not yet been reported. Here we demonstrate that human thymocytes and peripheral blood lymphocytes (PBL) synthesize PRL in primary culture. The principal form produced by thymocytes is 24 kilodaltons (kDa), essentially the same size as pituitary PRL, while PBL produced a 27-kDa variant. Size heterogeneity was evident, with products detected ranging from 21-29 kDa in various tissue samples, a phenomenon also found to occur in human pituitary and decidual PRL. Thymocytes and PBLs also synthesized a low mol wt form (11 kDa) that was released into culture supernatants concurrently with the larger PRL. The 24- and 11-kDa forms expressed PRL-like bioactivity in the Nb2 node lymphoma bioassay, further supporting their PRL-like nature. Expression of these PRLs was regulated by mitogen stimulation in thymocytes, but was constitutively produced in PBL. Northern blot analysis of thymocyte RNA using a human PRL cDNA probe detected a single PRL-like mRNA, which was significantly larger than human pituitary PRL mRNA. This was constitutively present in unstimulated thymocytes. Taken together, these data demonstrate that normal human lymphocytes synthesize bioactive PRLs similar in size to those produced by the pituitary. The presence of a single PRL mRNA suggests that the size variation observed in these proteins is probably due to posttranslational modification, such as proteolysis and glycosylation.

Different mechanisms of decreased drug accumulation in doxorubicin and mitoxantrone resistant variants of the MCF7 human breast cancer cell line.

We selected two drug resistant variants of the MCF7 human breast cancer cell line by chronic in vitro exposure to doxorubicin (MCF7/D40 cell line) and mitoxantrone (MCF7/Mitox cell line), respectively. The cell lines are similar in growth characteristics including doubling time, DNA synthetic phase and cell size. Resistance to mitoxantrone conferred only partial resistance to doxorubicin; whereas resistance selected for doxorubicin appeared to confer complete resistance to mitoxantrone. Both agents selected for cross resistance to the Vinca alkaloids. MCF7/D40 cells display a classic-multi-drug resistance phenotype with expression of P-glycoprotein, decreased drug accumulation relative to the parental line and reversal of drug accumulation and drug resistance by verapamil. MCF7/Mitox cells likewise display resistance to multiple drugs, but in contrast to MCF7/D40 cells do not express P-glycoprotein by immunoblot or RNA blot analysis. Net drug accumulation in MCF7/Mitox cells was decreased relative to the parental cells but there was no selective modulation of drug accumulation or in vitro drug resistance by the addition of verapamil. Efflux of mitoxantrone was enhanced in both the MCF7/D40 and MCF7/Mitox cell lines relative to the MCF7/S cell line. We conclude that the two drug resistant cell lines have different mechanisms of decreased drug accumulation.

Early life stage toxicity tests with a saltwater fish: effects of eight chemicals on survival growth, and development of sheepshead minnows (Cyprinodon variegatus).

Flow-through, acute (96-h), and early life stage (28-d after hatch) toxicity tests were performed with eight chemical on a saltwater fish, sheepshead minnows (Cyprinodon variegatus). Chemical effects on survival, growth, and development were determined. Maximum acceptable toxicant concentrations (MATCs) were greater than 3.2 less than 7.7 mg/l for toluene, greater than 0.52 greater than 0.97 mg/l for acenaphthene, greater than 80 less than 156 mg/l for isophorone, greater than 10 less than 16 mg/l for 4-nitrophenol, greater than 4.8 less than 8.5 mg/l for bromoform, greater than 0.39 less than 0.79 mg/l for 1-chloronaphthalene, greater than 0.09 less than 0.18 mg/l for 1, 2, 4, 5-tetrachlorobenzene, and less than 0.36 mg/l for 2, 4-dichloro-6-methylphenol; application factors were 0.25-0.59, 0.17-0.31, greater than or equal to 0.57, 0.31-0.50, greater than or equal to 0.68, greater than or equal to 0.56, 0.27-0.54, and less than 0.10. respectively. Test results reported here were compared with results of static, acute toxicity tests conducted previously with six species of aquatic organisms and the same chemicals.

Chlordane: effects on several estuarine organisms.

Dynamic marine toxicity tests were performed with technical grade chlordan and eastern oysters (Crassostrea virginica), pink shrimp (Penaeus duorarum), grass shrimp (Palaemonetes pugio), sheepshead minnows (Cyprinodon variegatus), and pinfish (Lagodon rhomboides). The 96-hr LC20S (and 95% confidence limits) based on measured concentrations of chlordane (in mug/liter) are: ping shrimp 0.4 (0.3-0.6); grass shrimp, 4.8 (4.0-6.0); sheepshead minnows, 24.5 (19.9-28.6); and pinfish, 6.4 (5.0-7.3). The 96-hr EC50 for eastern oysters was 6.2 (4.8-7.9). In a flow-through test, embryos and fry of sheepshead minnows were exposed to average measured concentrations of chlordane from 1.3 to 36.0 mug/liter for 28 days. Neither fertilization success nor embryo survival was affected by the concentrations of chlordane to which these life stages were exposed. However, sheepshead minnow fry did not survive for more than 10 days in chlordane concentrations greater than 7.1 mug/liter.

Toxicity of Aroclor-R 1254 and its physiological activity in several estuarine organisms.

The occurrence of high concentrations of a PCB (Aroclor 1254) in the Pensacola estuary prompted field and laboratory studies by the Gulf Breeze Environmental Research Laboratory (EPA). Monitoring of the estuary indicates the chemical is present in all components--particularly in sediments and fishes. Residues appear to be diminishing in sediments. Toxicity tests show estuarine species sensitive at ppb concentrations in water, with a ciliate protozoan (Tetrahymena pyriformis W), (Fundulus similis), affected at or near 1.0 ppb. Tissue concentrations of Aroclor 1254 similar to those found in natural populations of shrimps from the contaminated estuary were successfully duplicated in laboratory experiments. Shrimps also concentrated the PCB from very low concentrations (0.04 ppb) in the water. Three estuarine species demonstrated pathologic changes at tissue and cellular level after chronic exposure to the chemical. Oysters (Crassostrea virginica) developed abnormal infiltration of leukocytes in the connective tissue, spot (Leiostomus xanthurus) developed fatty changes in their livers, and shrimp (Penaeus duorarum) developed crystalloids in hepatopancreatic nuclei.