Spatial and temporal changes in multiple hormone groups during lateral bud release shortly following apex decapitation of chickpea (Cicer arietinum) seedlings

Although the co-ordination of promotive root-sourced cytokinin (CK) and inhibitory shoot apex-sourced auxin (IAA) is central to all current models on lateral bud dormancy release, control by those hormones alone has appeared inadequate in many studies. Thus it was hypothesized that the IAA : CK model is the central control but that it must be considered within the relevant timeframe leading to lateral bud release and against a backdrop of interactions with other hormone groups. Therefore, IAA and a wide survey of cytokinins (CKs), were examined along with abscisic acid (ABA) and polyamines (PAs) in released buds, tissue surrounding buds and xylem sap at 1 and 4 h after apex removal, when lateral buds of chickpea are known to break dormancy. Three potential lateral bud growth inhibitors, IAA, ABA and cis-zeatin 9-riboside (ZR), declined sharply in the released buds and xylem following decapitation. This is in contrast to potential dormancy breaking CKs like trans-ZR and trans-zeantin 9-riboside 5'phosphate (ZRMP), which represented the strongest correlative changes by increasing 3.5-fold in xylem sap and 22-fold in buds. PAs had not changed significantly in buds or other tissues after 4 h, so they were not directly involved in the breaking of bud dormancy. Results from the xylem and surrounding tissues indicated that bud CK increases resulted from a combination synthesis in the bud and selective loading of CK nucleotides into the xylem from the root.

Transport and metabolism of xylem cytokinins during lateral bud release in decapitated chickpea (Cicer arietinum) seedlings

Although cytokinins (CKs) are widely thought to have a role in promoting shoot branching, there is little data supporting a causative or even a correlative relationship between endogenous CKs and timing of bud outgrowth. We previously showed that lateral bud CK content increased rapidly following shoot decapitation. However, it is not known whether roots are the source of this CK. Here, we have used shoot decapitation to instantaneously induce lateral bud release in chickpea seedlings. This treatment rapidly alters rate and direction of solvent and solute (including CK) trafficking, which may be a passive signalling mechanism central to initiation of lateral bud release. To evaluate changes in xylem transport, intact and decapitated plants were infiltrated with [H-3]zeatin riboside ([H-3]ZR), a water-soluble blue dye or [H-3]H2O by injection into the hypocotyl. All three tracers were recovered in virtually all parts of the shoot within I h of injection. In intact plants, solute accumulation in the lateral bud at node 1 was significantly less than in the adjacent stipule and nodal tissue. In decapitated plants, accumulation of [H-3]ZR and of blue dye in the same bud position was increased 3- to 10-fold relative to intact plants, whereas content of [H-3]H2O was greatly reduced indicating an increased solvent throughput. The stipule and cut stem, predicted to have high evapotranspiration rates, also showed increased solute content accompanied by enhanced depletion of [H-3]H2O. To assess whether metabolism modifies quantities of active CK reaching the buds, we followed the metabolic fate of [H-3]ZR injected at physiological concentrations. Within 1 h, 80-95% of [H-3]ZR was converted to other active CKs (mainly zeatin riboside-5'phosphate (ZRMP) and zeatin (Z)), other significant, but unconfirmed metabolites some of which may be active (O-acetylZR, O-acetylZRMP and a compound correlated with sites of high CK-concentrations) and inactive catabolites (adenosine, adenine, 5'AMP and water). Despite rapid metabolic degradation, the total active label, which was indicative of CK concentration in buds, increased rapidly following decapitation. It can be inferred that xylem sap CKs represent one source of active CKs appearing in lateral buds after shoot decapitation.

Lateral epicondylalgia: a musculoskeletal physiotherapy perspective

Tennis elbow or lateral epicondylalgia (LE) is a challenging musculoskeletal condition to treat. This is largely due to the lack of research-based evidence of the clinical efficacy of the myriad of treatment approaches espoused in the literature. In view of this, successful rehabilitation of LE is based on choosing treatments that address the physical impairments found during clinical examination. The primary physical impairment in LE is a deficit in grip strength predominately due to pain and its consequences on motor function. Hence the mainstay of successful management of this condition is therapeutic exercise, providing it is not pain provocative. Adjunctive procedures such as manipulative therapy and sports taping techniques have recently been shown to provide substantial initial pain relief. Early relief of pain in the rehabilitation program helps accelerate recovery and most importantly motivates the client to persist with the therapeutic exercise program. The manipulative therapy and taping treatments presented in this masterclass warrant consideration in the clinical best practice management of LE, and serve as a model for other similar musculoskeletal conditions. (C) 2003 Elsevier Science Ltd. All rights reserved.

Dysarthria and dysphagia following treatment for a fourth ventricle choroid plexus papilloma

The present case report describes the presence of a persistent dysarthria and dysphagia as a consequence of surgical intervention for a choroid plexus papilloma (CPP). WM was a nine year ten month old male who at the time of the present study was seven years post-surgery. A comprehensive perceptual and instrumental test battery was used to document the nature of the dysarthria incorporating all components of speech production including respiration, phonation, resonance, articulation, and prosody. The nature of the dysphagia was evaluated through the use of videofluoroscopic evaluation of swallowing (VFS). Assessments confirmed the presence of a LMN dysarthria, marked by deficits in phonation, respiration, and prosody. Dysphagia assessment revealed deficits in oral preparatory, oral and pharyngeal stages of the swallow. The presence of persistent dysarthria and dysphagia in this case has a number of important implications for the management of children undergoing surgery for fourth ventricle CPPs, in particular the need for appropriate treatment, as well as counselling prior to surgery of the possible negative outcomes related to speech and swallowing. (C) 2003 Elsevier Science Ltd. All rights reserved.

Hypoalgesia induced by elbow manipulation in lateral epicondylalgia does not exhibit tolerance

Previous studies have demonstrated that the initial hypoalgesic effect of spinal manipulative therapy was not antagonized by naloxone and did not exhibit tolerance with repeated applications. The implication is that endogenous opioid mechanisms of pain relief are probably not at play in spinal manipulative therapy. The role of endogenous opioid peptides in manipulation of the peripheral joints has not been investigated. The aim of this study was to evaluate whether the initial hypoalgesic effect of a peripheral manipulative technique (mobilization-with-movement treatment for the elbow) demonstrated a tolerance to repeated applications (ie, reduction in magnitude of effect over repeated applications). Twenty-four participants with unilateral chronic lateral epicondylalgia participated in the study. A repeated measures study was conducted to examine the effect of repeated applications of the mobilization-with-movement treatment for the elbow on 6 separate treatment occasions at least 2 days apart. Pain-free grip strength and pressure pain threshold were chosen as the pain-related outcome measures. Changes in the percent maximum possible effect scores of measures of hypoalgesia were evaluated across the 6 treatment sessions by using linear trend analysis. The results showed no significant difference for the hypoalgesic effect of the treatment technique between sessions (P >.05). This peripheral manipulative therapy treatment technique appeared to have a similar effect profile to previously studied spinal manipulative therapy techniques, thereby contributing to the body of knowledge that indicates that manipulative therapy most likely induces a predominant non-opioid form of analgesia.

Ca2+-activated K+(BK) channel inactivation contributes to spike broadening during repetitive firing in the rat lateral amygdala

In many neurons, trains of action potentials show frequency-dependent broadening. This broadening results from the voltage-dependent inactivation of K+ currents that contribute to action potential repolarisation. In different neuronal cell types these K+ currents have been shown to be either slowly inactivating delayed rectifier type currents or rapidly inactivating A-type voltage-gated K+ currents. Recent findings show that inactivation of a Ca2+-dependent K+ current, mediated by large conductance BK-type channels, also contributes to spike broadening. Here, using whole-cell recordings in acute slices, we examine spike broadening in lateral amygdala projection neurons. Spike broadening is frequency dependent and is reversed by brief hyperpolarisations. This broadening is reduced by blockade of voltage-gated Ca2+ channels and BK channels. In contrast, broadening is not blocked by high concentrations of 4-aminopyridine (4-AP) or alpha-dendrotoxin. We conclude that while inactivation of BK-type Ca2+-activated K+ channels contributes to spike broadening in lateral amygdala neurons, inactivation of another as yet unidentified outward current also plays a role.

Should we be evaluating the ventricle or the myocardium? Advances in tissue characterization

The assessment of left ventricular (LV) dysfunction has become the most frequent indication for echocardiography, a growth that has been driven by the epidemic of heart failure. The value of echocardiography for assessing LV dysfunction is unquestionable, the quantification of both LV systolic and diastolic dysfunction being a reliable indicator of mortality. 1,2 Nonetheless, whereas the ejection fraction and diastolic assessment are important clinical parameters, they are highly dependent on loading and may produce abnormal results under unusual loading conditions. Moreover, in a number of situations where the LV is evaluated, although the overall function is an important finding, the referring clinician is really requesting an assessment of the nature of the underlying myocardial tissue (Table 1). Indeed, in some situations (eg, among family members of patients with a cardiomyopathy) questions arise about the presence of pathology despite the presence of normal ventricular function. Traditionally, it has been difficult to obtain this information because of the lack of sufficiently sensitive parameters, but a number of new developments have shown such success in this area that the clinical application of tools to assess the myocardium in routine practice appears finally to be a realistic proposition.

An Analytical Solution for the Elastic Lateral-Distortional Buckling of I-section Beams

Lateral-distortional buckling may occur in I-section beams with slender webs and stocky flanges. A computationally efficient method is presented in this paper to study this phenomenon. Previous studies on distortional buckling have been on the use of 3(rd) and 5(th) order polynomials to model the displacements. The present study provides an alternative way, using Fourier Series, to model the behaviour. Beams of different cross-sectional dimensions, load cases and restraint conditions are examined and compared. The accuracy and versatility of the method are verified by calibrating against the results of other published studies. The present method is believed to be a simple and efficient way of determining the buckling load and mode shapes of I-section beams that are susceptible to lateral-distortional buckling modes.

Opioids Inhibit Lateral Amygdala Pyramidal Neurons by Enhancing A Dendritic Potassium Current

Pyramidal neurons in the lateral amygdala discharge trains of action potentials that show marked spike frequency adaptation, which is primarily mediated by activation of a slow calcium-activated potassium current. We show here that these neurons also express an alpha-dendrotoxin- and tityustoxin-Kalpha-sensitive voltage-dependent potassium current that plays a key role in the control of spike discharge frequency. This current is selectively targeted to the primary apical dendrite of these neurons. Activation of mu-opioid receptors by application of morphine or D-Ala(2)-N-Me-Phe(4)-Glycol(5)-enkephalin (DAMGO) potentiates spike frequency adaptation by enhancing the alpha-dendrotoxin-sensitive potassium current. The effects of mu-opioid agonists on spike frequency adaptation were blocked by inhibiting G-proteins with N-ethylmaleimide (NEM) and by blocking phospholipase A(2). Application of arachidonic acid mimicked the actions of DAMGO or morphine. These results show that mu-opioid receptor activation enhances spike frequency adaptation in lateral amygdala neurons by modulating a voltage-dependent potassium channel containing Kv1.2 subunits, through activation of the phospholipase A(2)-arachidonic acid-lipoxygenases cascade.

A systematic review and meta-analysis of clinical trials on physical interventions for lateral epicondylalgia

A systematic review of the literature on the effectiveness of physical interventions for lateral epicondylalgia ( tennis elbow) was carried out. Seventy six randomised controlled trials were identified, 28 of which satisfied the minimum criteria for meta-analysis. The evidence suggests that extracorporeal shock wave therapy is not beneficial in the treatment of tennis elbow. There is a lack of evidence for the long term benefit of physical interventions in general. However, further research with long term follow up into manipulation and exercise as treatments is indicated.

Independent roles of calcium and voltage-dependent potassium currents in controlling spike frequency adaptation in lateral amygdala pyramidal neurons

The calcium-dependent afterhyperpolarization (AHP) that follows trains of action potentials is responsible for controlling action potential firing patterns in many neuronal cell types. We have previously shown that the slow AHP contributes to spike frequency adaptation in pyramidal neurons in the rat lateral amygdala. In addition, a dendritic voltage-gated potassium current mediated by Kv1.2-containing channels also suppresses action potential firing in these neurons. In this paper we show that this voltage-gated potassium current and the slow AHP act together to control spike frequency adaptation in lateral amygdala pyramidal neurons. The two currents have similar effects on action potential number when firing is evoked either by depolarizing current injections or by synaptic stimulation. However, they differ in their control of firing frequency, with the voltage-gated potassium current but not the slow AHP determining the initial frequency of action potential firing. This dual mechanism of controlling firing patterns is unique to lateral amygdala neurons and is likely to contribute to the very low levels of firing seen in lateral amygdala neurons in vivo.