A Statistical Approach to Provide Individualized Privacy for Surveys

In this paper we propose an instrument for collecting sensitive data that allows for each participant to customize the amount of information that she is comfortable revealing. Current methods adopt a uniform approach where all subjects are afforded the same privacy guarantees; however, privacy is a highly subjective property with intermediate points between total disclosure and non-disclosure: each respondent has a different criterion regarding the sensitivity of a particular topic. The method we propose empowers respondents in this respect while still allowing for the discovery of interesting findings through the application of well-known inferential procedures.     

Effects of Various Levels of CO(2) on the Induction of Crassulacean Acid Metabolism in Portulacaria afra (L.) Jacq

In response to water stress, Portulacaria afra (L.) Jacq. (Portulacaceae) shifts its photosynthetic carbon metabolism from the Calvin-Benson cycle for CO₂ fixation (C₃) photosynthesis or Crassulacean acid metabolism (CAM)-cycling, during which organic acids fluctuate with a C₃-type of gas exchange, to CAM. During the CAM induction, various attributes of CAM appear, such as stomatal closure during the day, increase in diurnal fluctuation of organic acids, and an increase in phosphoenolpyruvate carboxylase activity. It was hypothesized that stomatal closure due to water stress may induce changes in internal CO₂ concentration and that these changes in CO₂ could be a factor in CAM induction. Experiments were conducted to test this hypothesis. Well-watered plants and plants from which water was withheld starting at the beginning of the experiment were subjected to low (40 ppm), normal (ca. 330 ppm), and high (950 ppm) CO₂ during the day with normal concentrations of CO₂ during the night for 16 days. In water-stressed and in well-watered plants, CAM induction as ascertained by fluctuation of total titratable acidity, fluctuation of malic acid, stomatal conductance, CO₂ uptake, and phosphoenolpyruvate carboxylase activity, remained unaffected by low, normal, or high CO₂ treatments. In well-watered plants, however, both low and high ambient concentrations of CO₂ tended to reduce organic acid concentrations, low concentrations of CO₂ reducing the organic acids more than high CO₂. It was concluded that exposing the plants to the CO₂ concentrations mentioned had no effect on inducing or reducing the induction of CAM and that the effect of water stress on CAM induction is probably mediated by its effects on biochemical components of leaf metabolism.     

Plasma Corticosterone, Motor Activity and Metabolic Circadian Patterns in Streptozotocin-Induced Diabetic Rats

Experiments were conducted in male rats to study the effects of streptozotocin-induced diabetes on circadian rhythms of (a) plasma corticosterone concentrations; (b) motor activity; and (c) metabolic patterns. Animals were entrained to LD cycles of 12: 12 hr and fed ad libitum.

A daily rhythm of plasma corticosterone concentrations was found in controls animals with peak levels at 2400 hr and low values during the remaining hours. This rhythm was statistically confirmed by the cosinor method and had an amplitude of 3.37μg/100 ml and the acrophase at 100 hr. A loss of the normal circadian variation was observed in diabetic animals, with a nadir at the onset of light period and high values throughout the remaining hours; cosinor analysis of these data showed no circadian rhythm, delete and a higher mean level than controls.

As expected, normal rats presented most of their motor activity during the dark period with 80+ of total daily activity; the cosinor method demonstrated a circadian rhythm with an amplitude of 60+ of the mean level and the acrophase at 0852 hr. Both diabetic and control rats showed a similar activity during the light phase, but diabetic animals had less activity than controls during the night and their percentage of total daily activity was similar in both phases of the LD cycle (50+ for each one). With the cosinor method we were able to show the persistence of a circadian rhythm in the motor activity of diabetic rats, but with a mesor and amplitude lower than in controls (amplitude rested at 60+ of the mean level) and its acrophase advanced to 0148 hr.

The metabolic activity pattern of diabetic rats also changed: whereas controls showed a greater metabolic activity during the night (70+ food; 82+ water; 54+ urine; 67+ faeces), diabetics did not show differences between both phases of the LD cycle. Water ingested and urine excreted by the diabetic group were higher than normal during light and dark periods; food consumed and faeces excreted were higher than controls only in the light phase.

These data suggest that alterations in circadian rhythms of plasma corticosterone and motor activity are consecutive to the loss of the feeding circadian pattern, due to polyphagia and polydipsia showed by these animals, which need to extend intakes during the light and dark phases.     

Short communication: Effect of water activity on cell growth and phenol oxidase production by Streptomyces cyaneus var. viridochromogenes in surface culture

In surface cultures of Streptomyces cyaneus var. viridochromogenes, NaCl depressed water activity (a _w) without supporting growth. Reducing a _w from 0.987 to 0.951 led to 3- and 4-fold increases in intracellular and extracellular phenol oxidase activities, respectively.     

大鼠胼胝体内神经肽Y免疫反应阳性纤维的发育

本实验用免疫组织化学ＡＢＣ法研究了大鼠胼胝体内神经肽Ｙ免疫反应阳性（ＮＰＹ－ＩＲ）纤维的生后发育。结果发现,许多ＮＰＹ－ＩＲ纤维在大鼠出生时便存在于胼胝体内。ＮＰＹ－ＩＲ胼胝体纤维的密度在生后１周内继续逐渐增高,在第２周内达到最高峰。之后,ＮＰＹ－ＩＲ胼胝体纤维的密度逐渐下降,至第３周末时接近成年时的水平,即仅有少量ＮＰＹ－ＩＲ纤维存在于胼胝体内。这些结果提示在大鼠早期生后发育过程中许多ＮＰＹ－ＩＲ胼胝体纤维是暂时性的,其作用可能与大脑皮质的机能发育有关。     

Immunological mediation of gonadal effects on experimental murine cysticercosis caused by Taenia crassiceps metacestodes.

Female BALB/c mice are naturally more susceptible than males to intraperitoneal experimental infection with Taenia crassiceps metacestodes. Gonadectomy tends to equalize susceptibility between sexes by reducing in half the mean individual intensity of females and by tripling that of males. The effect of gonadectomy is seen only in mice with intact immune systems but not in irradiated mice. Purified sex hormones (17-beta estradiol, testosterone, and progesterone) do not affect cysticercus reproduction or growth in vitro. Thus, gonadal effect on mouse susceptibility to cysticercosis appears to be mediated via the immune system, and it is probably not the consequence of the major sex steroids acting directly upon the parasites. Because sublethal irradiation increases the intensity in gonadectomized females and intact males, whereas that of gonadectomized males and intact females remains unchanged, irradiation results are consistent with the hypothesis that immunological events that participate in controlling the growth of cysticerci are inhibited by ovaries and stimulated by testes.     

HMGB1 Mediates Cognitive Impairment in Sepsis Survivors

Severe sepsis, a syndrome that complicates infection and injury, affects 750,000 annually in the United States. The acute mortality rate is approximately 30%, but, strikingly, sepsis survivors have a significant disability burden: up to 25% of survivors are cognitively and physically impaired. To investigate the mechanisms underlying persistent cognitive impairment in sepsis survivors, here we developed a murine model of severe sepsis survivors following cecal ligation and puncture (CLP) to study cognitive impairments. We observed that serum levels of high mobility group box 1 (HMGB1), a critical mediator of acute sepsis pathophysiology, are increased in sepsis survivors. Significantly, these levels remain elevated for at least 4 wks after CLP. Sepsis survivors develop significant, persistent impairments in learning and memory, and anatomic changes in the hippocampus associated with a loss of synaptic plasticity. Administration of neutralizing anti-HMGB1 antibody to survivors, beginning 1 wk after onset of peritonitis, significantly improved memory impairments and brain pathology. Administration of recombinant HMGB1 to na?ve mice recapitulated the memory impairments. Together, these findings indicate that elevated HMGB1 levels mediate cognitive decline in sepsis survivors, and suggest that it may be possible to prevent or reverse cognitive impairments in sepsis survivors by administration of anti-HMGB1 antibodies.     

Seed to seedling transitions in successional habitats across a tropical landscape

Recognition that tree recruitment depends on the balance between seed arrival and seedling survival has led to a surge of interest in seed‐dispersal limitation and seedling‐establishment limitation in primary forests. Virtually unaddressed are comparisons of this balance in mature and early successional habitats. We assessed seed rain and seedling recruitment dynamics of tree species in primary forest, secondary forest and pasture released from grazing in a tropical agricultural landscape. Seed to seedling ratios (seed effectiveness; Φ_i) for 43 species in southern Mexico determined differences in the extent to which seeds produced seedlings by habitat, life history, and dispersal mode. Reproductive potential as estimated by the transition from seed rain to seedling recruitment, differed by habitats, and varied dramatically by life history and dispersal mode. Expected recruit densities (E_it) were higher for animal‐dispersed than wind‐dispersed species, and for non‐pioneer than pioneer species. Non‐pioneers and animal‐dispersed species had higher expected relative recruit abundance (ε_it) in primary forest (median of 4 seeds recruit^?1) whereas in secondary forest wind‐dispersed pioneers had the highest expected relative recruit abundance (median of 16 seeds per recruit). In pastures, wind‐dispersed pioneer species were most successful with many more seeds per recruit (median of 291) than both forest habitats. Seeds per recruit (Φ_i) appeared to decrease with increase in seed mass for 43 species for which data were available (r = –0.55, P < 0.001). This was associated with a negative correlation of Φ_i with seed size in primary forest (r = –0.50, P = 0.08 for 13 species); Φ_i was not correlated with seed size in secondary forest (n = 16) or pasture (n = 14). Metrics of seeds per recruit, expected recruit density and expected relative recruit abundance dramatically illustrate differences in barriers to recruitment in successional habitats.