Foliage shedding in deciduous forests lifts up long-distance seed dispersal by wind

Seed terminal velocity and release height are recognized as key biotic determinants of long-distance dispersal (LDD) of seeds by wind. Yet, potential determinants at the ecosystem level, such as seasonal dynamics in foliage density characterizing many deciduous forests, have received much less attention. We integrated detailed field observations and experiments with a mechanistic wind dispersal model to assess how seasonal variation in foliage density, estimated by leaf-area index (LAI), affects LDD in deciduous forests. We found that the model, previously shown to accurately predict seed dispersal by wind, also reliably describes the effects of LAI variation on wind statistics for a wide range of canopy types. Sparser canopies are characterized by more organized vertical eddy motion that promotes LDD by uplifting seeds to higher elevations where winds are stronger. Yet, sparser canopies are also characterized by reduced mean windspeed aloft. We showed that former effect more than compensates for the latter, i.e., conditions of low LAI are favorable for LDD. This may account for the tendency of many temperate tree species to restrict seed release to either early spring or late fall, when LAI is relatively low. Sensitivity analysis reveals that the typical seasonal variation in LAI can be more important to LDD of seeds by wind than the natural variation in seed terminal velocity. Because our model accurately describes the effects of LAI variation for distinctly different sites, species, and life forms, we suggest that its results reflect a general association between LDD and foliage density dynamics.     

Coping with critical life events and lack of control--the exertion of control

Coping strategies in relation to unfair treatment or conflicts at work are discussed. ‘Covert coping’ has been assessed by means of a short questionnaire. Its relationship with cardiovascular risk and sick leave has been examined in an epidemiological study (WOLF) of working men and women in Stockholm. The findings indicate that in men ‘covert coping’ is associated with elevated cardiovascular risk and prospective long-term sick leave. In women such a coping strategy is related to current sick leave, but not to cardiovascular risk or long-term sick leave. Openness of coping strategies is also discussed in relation to bouts of anger preceding myocardial infarction. Another epidemiological study (SHEEP, ONSET) has shown that severe bouts of anger are reported significantly more often than expected during the hour preceding myocardial infarction. This was not the case in subjects who reported ‘open coping patterns’, however. Openness of coping strategies is partly determined by the working climate—the higher the decision latitude, the less ‘covert’ the coping strategies. The results support the idea that dialogue in the work place may be health promoting.     

Differential expression of matrix metalloproteinases and their inhibitors in human and mouse lung development

Lung development is a highly orchestrated process characterized by timed expression and activation of growth factor and protease/antiprotease systems. This interplay is essential in regulating vasculogenesis, alveolarization, and epithelial to mesenchymal transition during lung development. Alterations in the proteolytic/antiproteolytic balance of the lung have been associated with several respiratory diseases characterized by changes in the lung extracellular matrix (ECM). Here, we characterized the expression pattern of matrix metalloproteases (MMP) and their inhibitors, the tissue inhibitors of metalloproteases (TIMP), in human and mouse lung development. Using MMP/TIMP expression arrays, RT-PCR, Western Blotting, and ELISA analyses, we demonstrate that fetal human lung is characterized by a dominant proteolytic profile with high MMP-2 and little TIMP-3 expression. Adult human lung, in contrast, exhibits a more anti-proteolytic profile with decreased MMP-2 and increased TIMP-3 expression. MMP-14, MMP-20, TIMP-1, and TIMP-2 were constitutively expressed, irrespective of the developmental stage. Similar results were obtained using mouse lungs of different developmental stages, with the addition that in mouse lung, TIMP-2 and TIMP-3 were upregulated as lung development progressed. Exposure of neonatal mice to chronic hypoxia (10% O2), a stimulus that leads to an arrest of lung development, resulted in upregulation of MMP-2 with a concomitant downregulation of TIMP-2. These results provide a comprehensive analysis of MMP and TIMP expression during human and mouse lung development. MMP-2, TIMP-2, and TIMP-3 may be key regulatory enzymes during lung development, possibly through their complex action on ECM components, membrane receptor ectodomain shedding, and growth factor bioactivity.     

Opposite relationship between circulating soluble CD14 concentration and endothelial function in diabetic and nondiabetic subjects

Recent prospective studies indicate endothelial dysfunction and increased risk for cardiovascular events in patients with serological evidence of multiple infections. Soluble CD14 (sCD 14) plays a key role in the neutralization of lipopolysaccharide (LPS), a well-established bacterial product inducing endothelial dysfunction. Insulin resistance was recently identified as a significant factor influencing circulating sCD 14 concentration. Thus, we investigated the association of circulating sCD14 and endothelial dysfunction in subjects with well-established insulin resistance (patients with type 2 diabetes, n = 40) compared to control non-diabetic subjects (n = 100). To further explore the underlying mechanisms, we also analysed C-reactive protein and circulating NO2-/NO3- and cyclic GMP in the diabetic group. Serum sCD 14 concentration (ELISA) was found to be differently associated with endothelium-dependent vasodilatation (EDVD, high-resolution ultrasound) in diabetic and non-diabetic subjects. In nondiabetic subjects, serum sCD14 and C-reactive protein correlated negatively with EDVD (r = -0.21, p = 0.03, and r = -0.21, p = 0.03, respectively). In a partial correlation analysis, these associations remained significant after controlling for age and weight (sCD 14 and EDVD, r = -0.23, p = 0.023; C-reactive protein and EDVD, r = -0.21, p = 0.03; sCD14 and C-reactive protein, r = 0.30, p = 0.002). In contrast, sCD 14 was positively associated with EDVD in type 2 diabetic patients (r = 0.37, p = 0.019,). Interestingly, sCD14 was also associated with NO2-/NO3- in this group (r = 0.62, p = 0.001, n = 22). EDVD also correlated with cyclic GMP (r = 0.47, p = 0.03, n = 22). In summary, circulating sCD 14 is associated with endothelial function. While in non-diabetic subjects sCD14 behaves as an acute phase reactant, its role in type 2 diabetic patients should be further clarified. These findings need to be confirmed in further studies with larger number of patients.     

Development and localisation of GABA(A) receptor alpha1, alpha2, beta2 and gamma2 subunit mRNA in the chick optic tectum

An in situ hybridisation technique was used to analyse the spatial and temporal pattern of expression of the mRNA encoding the four gamma-aminobutyric acid A (GABA(A)) receptor subunits (alpha1, alpha2, beta2, and gamma2) in the developing chick optic tectum. As a rule, layer i, layer h, and transient cell compartment 3 (TCC3) show the highest levels of expression, especially of alpha1, alpha2 and beta2, which undergo striking changes as a function of time. Apart from these common features, the global pattern is highly complex and dynamic. Such complexity derives from the fact that each subunit exhibits a characteristically distinct pattern of expression and the temporal evolution of each differs in the different layers of the tectum. The influence of several developmental cell behaviours such as proliferation, neuronal migration, programmed cell death, and differentiation must be taken into account to understand pattern complexity and dynamics. Our results suggest that differences in the rate of subunit expression, particularly of alpha1, alpha2, and beta2, could have significant consequences on GABA(A) receptor complex subunit composition along development and on the functional properties of the GABA neurotransmitter system.     

Dose-dependent decrease of activation in bilateral amygdala and insula by lorazepam during emotion processing

BACKGROUND: Functional neuroimaging may elucidate the pathophysiologic features of anxiety disorders and the site of action of anxiolytic drugs. A large body of evidence suggests that the amygdala and associated limbic structures play a critical role in the expression of anxiety and may be treatment targets for anxiolytic drugs. OBJECTIVE: To determine whether lorazepam dose-dependently attenuates blood oxygenation level-dependent functional magnetic resonance imaging (BOLD fMRI) activation in the amygdala and associated limbic structures during an emotion face assessment task. PARTICIPANTS AND DESIGN: Fifteen healthy volunteers participated in a double-blind, placebo-controlled, randomized dose-response study. Subjects underwent imaging 3 times (at least a week apart) and were given either a single-dose placebo or 0.25 mg or 1.0 mg of lorazepam 1 hour prior to an MRI session. During fMRI, subjects completed an emotion face assessment task, which has been shown to elicit amygdala activation. MAIN OUTCOME MEASURES: The BOLD-fMRI activation in amygdala, insula, and medial prefrontal cortex during the emotion face assessment task. RESULTS: Lorazepam significantly attenuated the BOLD-fMRI signal in a dose-dependent manner in bilateral amygdala and insula but not in the medial prefrontal cortex. Lorazepam did not affect the BOLD-fMRI signal in the primary visual cortex. CONCLUSIONS: The current finding provides the first neuroimaging evidence of a dose-dependent change induced by an established therapeutic agent in brain regions known to be critical for the mediation of anxiety. This investigation may help to support the use of BOLD-fMRI with pharmacological probes to investigate the neural circuits underlying anxiety and the use of fMRI as a tool in the development of new anxiolytic agents.     

Reproducible loss of CA1 neurons following carotid artery occlusion combined with halothane-induced hypotension

The 2-vessel occlusion approach to produce global ischemia in rats requires concomitant reduction of systemic blood pressure. We have utilized the hypotensive effect of halothane administrated by artificial respiration to prevent respiratory arrest and to ensure stable physiological conditions. Systemic blood pressure was reduced to 40-45 mmHg by instant adjustments of the halothane concentration. Bilateral occlusion of the carotid arteries caused a profound and reproducible ischemia, as analyzed by laser-Doppler flowmetry. In the rats exposed to 11, 12, or 13 min of ischemia, 5% died and 5% developed seizures. The extent of neuronal death in CA1 was highly correlated to the duration of ischemia. Following 11 min of ischemia, CA1 neuronal cell death, as analyzed by Fluoro-Jade, was absent 1 day after injury, variable at day 4, and consistent at day 7. The numbers of cresyl violet- and NeuN-positive neurons at day 7 were 8% and 20% of control, respectively. OX42 immunoreactivity was low and variable at day 4, but pronounced at day 7. In conclusion, this rat global ischemia model is relatively simple to perform, has a low mortality, and produces a profound and highly reproducible delayed cell death of hippocampal CA1 neurons.     

Video assisted thoracoscopic surgery for spinal conditions

Video-assisted thoracoscopic surgery (VATS) has become an alternative treatment tool for a variety of spinal conditions in the last two decades. This endoscopic or "keyhole" approach minimizes the chest wall morbidity related to the traditional thoracotomy. The current indications for VATS are the same as in any open anterior spinal surgery. This article reviews the outcomes of VATS treatments in thoracic disc diseases, fractures, tumors and vertebral osteomyelitis. In addition, we have described our "learning curve" and surgical techniques using video-assisted thoracoscopic spinal releases and instrumentation in the treatment of 50 patients with adolescent idiopathic scoliosis.