Self-pollination by sliding pollen in Caulokaempferia coenobialis (Zingiberaceae)

Caulokaempferia coenobialis (Zingiberaceae) forms dense populations on steep cliffs in shady, humid monsoon forests in south China. It produces few consecutively opening bright yellow flowers that are 3 cm long and oriented parallel to the ground. Upon anther dehiscence at about 0600 hours, each pollen sac releases a drop of pollen onto the horizontally oriented style, and the two drops then merge to form an oily film that slowly flows toward the stigma, carrying out self-pollination between about 1500 and 0730 hours the next day. The distance covered by the pollen film is ca. 3 mm. There is no significant difference in fruit set between experimentally cross- and self-pollinated flowers or between naturally pollinated and bagged flowers. The low pollen/ovule ratio of 664 probably relates to the pollen grains being held together by pollen-connecting threads. The latter ensure that pollen grains always arrive as multiples, and this is the first report of such threads in the Zingiberaceae. During 35 h of observation at several locations and during three flowering periods, only three individual bees, five flies, and two butterflies visited single flowers. It remained unclear whether they affected pollination because no return visits were observed. The automatic selfing by pollen that reaches the stigma ca. 9 h after the onset of anthesis apparently constitutes a case of delayed selfing, providing reproductive reassurance in situations of low pollinator visitation

Stereologic Analysis of Tibial-Plateau Cartilage and Femoral Cancellous Bone in Guinea Pigs With Spontaneous Osteoarthritis

Background: Two strains of guinea pig develop spontaneous osteoarthritis of the knee. Although the disease evolves at different rates in the two strains, it is not known whether these differences are reflected in the structure of the cartilage and cancellous bone. Questions/purposes: We determined whether the three-dimensional structure of the tibial-plateau cartilage and femoral cancellous bone differed between the two strains. Methods: Six Dunkin-Hartley and six GOHI/SPF guinea pigs were evaluated. The animals were sacrificed at 11months of age. The 24 proximal tibias were used for a stereologic histomorphometric analysis of the tibial-plateau cartilage. The 24 femurs were used for a site-specific, three-dimensional quantitative analysis of the cancellous bone by micro-CT. Results: Compared to the GOHI/SPF guinea pigs, the tibial-plateau cartilage of the Dunkin-Hartley strain had a larger lesion volume (3.8% versus 1.5%) and a thicker uncalcified cartilage layer (0.042 versus 0.035mm), but a thinner calcified cartilage zone (0.008 versus 0.01mm) and a thinner subchondral cortical bone plate (0.035 versus 0.039mm). The femoral cancellous bone in the Dunkin-Hartley strain had a lower bone mineral density (477 versus 509mg/cm3). However, the trabeculae were thicker (3.91 versus 3.53 pixels) and farther apart (7.8 versus 5.6 pixels). The osteoarthritic changes in the cartilage were topographically mirrored in the subchondral bone. They were most severe on the medial side of the joint, particularly in the anterior region. Conclusions: Spontaneous osteoarthritis in the guinea pig is associated with site-specific changes in the articular cartilage layer, which are topographically mirrored in the underlying subchondral bone. Clinical Relevance: Three-dimensional structural information not revealed by two-dimensional radiography may help characterize the stages of osteoarthriti

Regularized Inversion of Aerosol Hygroscopic Growth Factor Probability Density Function: Application to Humidity-Controlled Fast Integrated Mobility Spectrometer Measurements

Aerosol hygroscopic growth plays an important role in atmospheric particle chemistry and the effects of aerosol on radiation and hence climate. The hygroscopic growth is often characterized by a growth factor probability density function (GF-PDF), where the growth factor is defined as the ratio of the particle size at a specified relative humidity to its dry size. Parametric, least-squares methods are the most widely used algorithms for inverting the GF-PDF from measurements of the humidified tandem differential mobility analyzer (HTDMA) and have been recently applied to the GF-PDF inversion from measurements of the humidity-controlled fast integrated mobility spectrometer (HFIMS). However, these least-squares methods suffer from noise amplification due to the lack of regularization in solving the ill-posed problem, resulting in significant fluctuations in the retrieved GF-PDF and even occasional failures of convergence. In this study, we introduce nonparametric, regularized methods to invert the aerosol GF-PDF and apply them to HFIMS measurements. Based on the HFIMS kernel function, the forward convolution is transformed into a matrix-based form, which facilitates the application of the nonparametric inversion methods with regularizations, including Tikhonov regularization and Twomey\u27s iterative regularization. Inversions of the GF-PDF using the nonparameteric methods with regularization are demonstrated using HFIMS measurements simulated from representative GF-PDFs of ambient aerosols. The characteristics of reconstructed GF-PDFs resulting from different inversion methods, including previously developed least-squares methods, are quantitatively compared. The result shows that Twomey\u27s method generally outperforms other inversion methods. The capabilities of Twomey\u27s method in reconstructing the pre-defined GF-PDFs and recovering the mode parameters are validated

Requirement for DNA Ligase IV during Embryonic Neuronal Development

The embryonic ventricular and subventricular zones (VZ/SVZ) contain the neuronal stem and progenitor cells and undergo rapid proliferation. The intermediate zone (IZ) contains nonreplicating, differentiated cells. The VZ/SVZ is hypersensitive to radiation-induced apoptosis. Ablation of DNA non-homologous end-joining (NHEJ) proteins, XRCC4 or DNA ligase IV (LigIV), confers ataxia telangiectasia mutated (ATM)-dependent apoptosis predominantly in the IZ. We examine the mechanistic basis underlying these distinct sensitivities using a viable LigIV (Lig4(Y288C)) mouse, which permits an examination of the DNA damage responses in the embryonic and adult brain. Via combined analysis of DNA breakage, apoptosis, and cell-cycle checkpoint control in tissues, we show that apoptosis in the VZ/SVZ and IZ is activated by low numbers of DNA double-strand breaks (DSBs). Unexpectedly, high sensitivity in the VZ/SVZ arises from sensitive activation of ATM-dependent apoptosis plus an ATM-independent process. In contrast, the IZ appears to be hypersensitive to persistent DSBs. NHEJ functions efficiently in both compartments. The VZ/SVZ and IZ regions incur high endogenous DNA breakage, which correlates with VZ proliferation. We demonstrate a functional G(2)/M checkpoint in VZ/SVZ cells and show that it is not activated by low numbers of DSBs, allowing damaged VZ/SVZ cells to transit into the IZ. We propose a novel model in which microcephaly in LIG4 syndrome arises from sensitive apoptotic induction from persisting DSBs in the IZ, which arise from high endogenous breakage in the VZ/SVZ and transit of damaged cells to the IZ. The VZ/SVZ, in contrast, is highly sensitive to acute radiation-induced DSB formation

Hospital fall prevention: a systematic review of implementation, components, adherence, and effectiveness.

ObjectivesTo systematically document the implementation, components, comparators, adherence, and effectiveness of published fall prevention approaches in U.S. acute care hospitals.DesignSystematic review. Studies were identified through existing reviews, searching five electronic databases, screening reference lists, and contacting topic experts for studies published through August 2011.SettingU.S. acute care hospitals.ParticipantsStudies reporting in-hospital falls for intervention groups and concurrent (e.g., controlled trials) or historic comparators (e.g., before-after studies).InterventionFall prevention interventions.MeasurementsIncidence rate ratios (IRR, ratio of fall rate postintervention or treatment group to the fall rate preintervention or control group) and ratings of study details.ResultsFifty-nine studies met inclusion criteria. Implementation strategies were sparsely documented (17% not at all) and included staff education, establishing committees, seeking leadership support, and occasionally continuous quality improvement techniques. Most interventions (81%) included multiple components (e.g., risk assessments (often not validated), visual risk alerts, patient education, care rounds, bed-exit alarms, and postfall evaluations). Fifty-four percent did not report on fall prevention measures applied in the comparison group, and 39% neither reported fidelity data nor described adherence strategies such as regular audits and feedback to ensure completion of care processes. Only 45% of concurrent and 15% of historic control studies reported sufficient data to compare fall rates. The pooled postintervention incidence rate ratio (IRR) was 0.77 (95% confidence interval = 0.52-1.12, P = .17; eight studies; I(2) : 94%). Meta-regressions showed no systematic association between implementation intensity, intervention complexity, comparator information, or adherence levels and IRR.ConclusionPromising approaches exist, but better reporting of outcomes, implementation, adherence, intervention components, and comparison group information is necessary to establish evidence on how hospitals can successfully prevent falls

Limitations of MTT and MTS-Based Assays for Measurement of Antiproliferative Activity of Green Tea Polyphenols

The chemopreventive effect of green tea polyphenols, such as (-)-epigallocatechin-3-gallate (EGCG), has been well demonstrated in cell culture studies. However, a wide range of IC(50) concentrations has been observed in published studies of the anti-proliferative activity of EGCG from different laboratories. Although the susceptibility to EGCG treatment is largely dependent on cancer cell type, the particular cell viability and proliferation assays utilized may significantly influence quantitative results reported in the literature.We compared five widely used methods to measure cell proliferation and viability after EGCG treatment using LNCaP prostate cancer cells and MCF-7 breast cancer cells. Both methods using dyes to quantify adenosine triphosphate (ATP) and deoxynucleic acid (DNA) showed accuracy in the measurement of viable cells when compared to trypan blue assay and results showed good linear correlation (r = 0.95). However, the use of MTT (3-(4,5-Dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide) and MTS (3-(4,5-dimethylthiazol-2-yl)-5-(3-carboxymethoxyphenyl)-2-(4-sulfophenyl)-2H-tetrazolium) as indicators of metabolically active mitochondria overestimated the number of viable cells by comparison with the ATP, DNA, or trypan blue determinations. As a result, the observed IC(50) concentration of EGCG was 2-fold higher using MTT and MTS compared to dyes quantifying ATP and DNA. In contrast, when cells were treated with apigenin MTT and MTS assays showed consistent results with ATP, DNA, or trypan blue assays.These results demonstrate that MTT and MTS -based assays will provide an underestimation of the anti-proliferative effect of EGCG, and suggest the importance of careful evaluation of the method for in vitro assessment of cell viability and proliferation depending on the chemical nature of botanical supplements