The use of intermittent trunk flexion to alleviate low back pain during prolonged standing

The current study examined of the effect of intermittent, short-term periods of full trunk flexion on the development of low back pain (LBP) during two hours of standing. Sixteen participants completed two 2-h standing protocols, separated by one week. On one day, participants stood statically for 2 h (control day); on the other day participants bent forward to full spine flexion (termed flexion trials) to elicit the flexion relaxation (FR) phenomenon for 5 s every 15 min (experimental day). The order of the control and experimental day was randomized. During both protocols, participants reported LBP using a 100 mm visual analogue scale every 15 min. During the flexion trials, lumbar spine posture, erector spinae and gluteus medius muscle activation was monitored. Ultimately, intermittent trunk flexion reduced LBP by 36% (10 mm) at the end of a 2-h period of standing. Further, erector spinae and gluteus medius muscle quietening during FR was observed in 91% and 65% of the flexion trials respectively, indicating that periods of rest did occurred possibly contributing to the reduction in LBP observed. Since flexion periods do not require any aids, they can be performed in most workplaces thereby increasing applicability.     

Spatial relationships between cacti and nurse shrubs in a semi-arid environment in central Mexico

Abstract. The Zapotitlán de las Salinas valley, central Mexico, harbours a high diversity of cacti. Pattern analysis indicated that the establishment of two columnar cacti, Neobuxbaumia tetetzo and Cephalocereus hoppenstedtii, and of three small globose cacti, Coryphantapallida, Mammillaria colina andM casoi, is aggregated and associated with perennial nurse shrubs. Some nurse species, Castela tortuosa, Caesalpinia melanadenia and Eupatorium spinosarum have a higher number of cacti beneath their canopies than would be expected by chance. A replacement pattern was found between the columnar cacti and their nurses, an aspect which was not found with the globose cacti. Following the assumption that protection against excessive radiation is the main factor determining the nurse effect, the azimuth orientation of the cacti with respect to their nurses was evaluated. Only Coryphanta pallida presented a non-random distribution with a tendency towards the North and West. The difference in maximum temperature between the soil surface under the different nurse species and of open spaces, which is reached at midday, was 16 °C. No significant differences were found in beneath-canopy temperatures for the three nurse species considered. Soil nitrogen levels were significantly lower beneath the different nurse plants than in open spaces. This result suggests that soil fertility is not an important factor in the nurse-plant phenomenon in Zapotitlán.     

血红蛋白A2现象发生机制的研究——“红细胞HbA2”为HbA2与HbA的结合产物

为了弄清血红蛋白A₂现象的发生机制,我们对“红细胞HbA₂”的化学组成进行了分析。“红细胞HbA₂”的双向电泳结果表明,它含有两种血红蛋白成分:一种相当于HbA,另一种很可能是溶血液HbA₂。其单向二次电泳结果也证明,它是由溶血液HbA₂和HbA所组成。结果初步说明,盘红细胞中HbA₂可能与HbA结合存在。两者可能有相互作用,也许这是产生血红蛋白A₂现象的原因。     

Development and validation of the K‐VSCOR for scoring Koebner's phenomenon in vitiligo/non‐segmental vitiligo

The relation of vitiligo/non‐segmental vitiligo (NSV) to Koebner's phenomenon is variably appreciated. Our objective was to develop and validate a simple clinical score for Koebner's phenomenon (KP) in patients with vitiligo/NSV. The study population was composed of 351 individuals in the development sample and 285 patients in the validation sample. Seven variables were independently associated with the presence of KP: disease duration of more than 3 yr, forehead + scalp areas, eyelids, wrists, genital + belt areas, knees and tibial crests. The score computed by the weighted sum of the rounded coefficients of these seven variables ranged from 0 to 56 (mean 38.39 ± 22.93). The probability of having KP was computed as follows: exp (?2.37 + 0.1*score)/exp [1 + (?2.37 + 0.1*score)]. When applying the score to each patient in the validation and the development sample, the score maintained adequate discrimination and calibration (AUC‐ROC = 0.78), arguing that KP can be adequately predicted using our score. Further studies should evaluate KP assessed by the K‐VSCOR in clinical practice with the aim to determine its association with clinical profile, course and treatment response of vitiligo.     

中国漳江口红树植物秋茄茎流特征及其影响因子

利用Granier热消散式探针法对福建漳江口国家级红树林自然保护区内红树植物秋茄的树干茎流密度(SFD)进行1年(2010年10月至2011年10月)的连续监测.结果表明: 季节和树干径级对秋茄树干茎流密度均有显著影响.在夏季,胸径(DBH)为8～10 cm时秋茄树干最外层2 cm处的SFD达到最大,为38.21 g·m^-2·s^-1,这与其他红树物种以及湿地乔木物种的茎流密度相当.不同径级(小、中、大径级分别为2～4、4～8、8～10 cm)秋茄每日整树蒸腾量(即水分日利用量)也呈现明显的季节变化,从冬季到夏季的波动值分别为0.14～0.19、0.94～1.45、1.96～3.43 kg·d^-1.通过整合各个径级秋茄树的日蒸腾量推算得到秋茄林的日蒸腾量,再全年累加计算得到秋茄林年总蒸腾量为100.38 mm,不到当地年降水量的6%.主要环境因子对秋茄林蒸腾速率(E_s)均有极显著影响(P<0.001),其中,光合有效辐射(PAR)和饱和水汽压差(VPD)是E_s最主要的驱动因子,解释了E_s 60%～92%的季节变异,且夏季秋茄E_s 对PAR和VPD的依赖性大于冬季.秋茄E_s与环境因子之间存在明显的时滞现象,需要在解释秋茄林E_s季节变异时加以考虑.     

The KEULE gene is involved in cytokinesis in Arabidopsis

 We present evidence to show that the KEULE gene of Arabidopsis is involved in cytokinesis. Mutant keule embryos have large multinucleate cells with gapped or incomplete cross walls, as well as cell wall stubs that are very similar to those observed upon caffeine inhibition of cytokinesis in plants. These defects are observed in all populations of dividing cells in the mutant, including calli, but less frequently in mature cells. Cell division appears to be slowed down, and the planes of cell division are often misoriented. In late embryos and seedlings, cross-wall formation usually appears complete, suggesting that the requirement for KEULE during cytokinesis is not absolute. Nonetheless, keule mutants die as seedlings with large polyploid cells. The bloated surface layer of keule seedlings does not uniformly behave like wild-type epidermis, and patches of this layer assume characteristics of the underlying ground tissue. The cytokinesis defect of keule mutants may influence aspects of cellular differentiation. Received: 24 April 1996 / Accepted: 11 June 1996     

Periodicity of infectivity of plasmodial gametocytes: the "Hawking phenomenon"

Five controlled experiments were performed to test the validity of the theory of nocturnal infectivity of gametocytes of Plasmodium. Two gave equivocal results probably because synchronicity of parasitaemia was low; the remaining three, in which a langur strain of P. cynomolgi was used, largely confirmed Hawking's work and in particular demonstrated the much greater production of oocysts after midnight as compared with midday feedings.     

Bisphenol A and its methylated congeners inhibit growth and interfere with microtubules in human fibroblasts in vitro

Bisphenol A (BPA), a monomer of polycarbonate plastics and epoxy resins, has previously been reported to induce micronuclei containing whole chromosomes in Chinese hamster V79 cells. In the present study, the aneuploidogenic potential of BPA was investigated in cultured human AG01522C fibroblasts. In contrast to the known aneugens diethylstilbestrol (DES) and 17beta-estradiol, which caused mitotic arrest and the induction of kinetochore-positive micronuclei, BPA did not induce micronuclei and inhibited the proliferation of AG01522C cells in G2 phase and probably also in G1 phase. Fluorescence microscopy of the BPA-treated cells after immunofluorescent staining of microtubules revealed structural abnormalities of the cytoplasmic microtubule complex (CMTC): densely stained rings and loops of tubulin were observed, which increased in number with increasing BPA concentration and were more stable against low temperature than normal microtubules. The mechanisms of the growth inhibition and the interference with microtubules elicited by BPA in AG01522C cells are presently unknown. The formation of rings and loops in the CMTC of AG01522C cells was also observed with two congeners of BPA carrying one and two, respectively, additional methyl groups in ortho-position to the phenolic hydroxyl group at each aromatic ring. However, in contrast to BPA itself, these congeners of BPA behaved "DES-like" by inducing mitotic arrest and kinetochore-positive micronuclei in AG01522C cells.     

The role of microtubules in establishing nuclear spatial patterns in multinucleate green algae

Summary In uninucleate cells, cytokinesis follows karyokinesis, thereby reestablishing a specific nucleus-to-cytoplasm ratio. In multinucleate cells, cytokinesis is absent or infrequent; no plasmalemma boundary defines the cytoplasmic territory of an individual nucleus. Several genera of large multinucleate green algae were examined with epifluorescence light microscopy to determine whether the patterns of cytoplasmic organization establish nuclear cytoplasmic domains. Randomly spaced nuclei, singular mitotic events and cytoplasmic streaming characterize the organization of two genera,Derbesia andBryopsis (Caulerpales). The cells ofValonia, Valoniopsis, Boergesenia, Ventricaria (Siphonocladales), andHydrodictyon (Chlorococcales) display regularly spaced nuclei which undergo synchronous divisions in a stationary cytoplasm. In the cytoplasm of genera with regularly spaced nuclei, microtubules radiate from all nuclei in late telophase-early interphase. These internuclear microtubule arrays are not found in algal genera with randomly spaced nuclei. It is hypothesized that these microtubule arrays play a role in establishing the cytoplasmic domain of each nucleus in genera with regularly spaced nuclei. Loss of microtubule arrays during the events of mitosis correlated positively with the increasing randomization of nuclear patterns in algae grown in microtubule inhibitors. Cytoplasmic domains were maintained when cells were grown in the same media in the dark. This suggests that, after a round of division, regular nuclear spacing in certain multinucleate algae is reestablished by internuclear microtubule arrays, which are not, however, required to maintain spacing during interphase.Dedicated to the memory of Professor Oswald Kiermayer