Similar patterns of leaf temperatures and thermal acclimation to warming in temperate and tropical tree canopies.

As the global climate warms, a key question is how increased leaf temperatures will affect tree physiology and the coupling between leaf and air temperatures in forests. To explore the impact of increasing temperatures on plant performance in open air, we warmed leaves in the canopy of two mature evergreen forests, a temperate Eucalyptus woodland and a tropical rainforest. The leaf heaters consistently maintained leaves at a target of 4 °C above ambient leaf temperatures. Ambient leaf temperatures (Tleaf) were mostly coupled to air temperatures (Tair), but at times, leaves could be 8-10 °C warmer than ambient air temperatures, especially in full sun. At both sites, Tleaf was warmer at higher air temperatures (Tair > 25 °C), but was cooler at lower Tair, contrary to the 'leaf homeothermy hypothesis'. Warmed leaves showed significantly lower stomatal conductance (-0.05 mol m-2 s-1 or -43% across species) and net photosynthesis (-3.91 µmol m-2 s-1 or -39%), with similar rates in leaf respiration rates at a common temperature (no acclimation). Increased canopy leaf temperatures due to future warming could reduce carbon assimilation via reduced photosynthesis in these forests, potentially weakening the land carbon sink in tropical and temperate forests.

Identifying drivers of leaf water and cellulose stable isotope enrichment in Eucalyptus in northern Australia.

Several previous studies have investigated the use of the stable hydrogen and oxygen isotope compositions in plant materials as indicators of palaeoclimate. However, accurate interpretation relies on a detailed understanding of both physiological and environmental drivers of the variations in isotopic enrichments that occur in leaf water and associated organic compounds. To progress this aim we measured δ18O and δ2H values in eucalypt leaf and stem water and δ18O values in leaf cellulose, along with the isotopic compositions of water vapour, across a north-eastern Australian aridity gradient. Here we compare observed leaf water enrichment, along with previously published enrichment data from a similar north Australian transect, to Craig-Gordon-modelled predictions of leaf water isotopic enrichment. Our investigation of model parameters shows that observed 18O enrichment across the aridity gradients is dominated by the relationship between atmospheric and internal leaf water vapour pressure while 2H enrichment is driven mainly by variation in the water vapour-source water isotopic disequilibrium. During exceptionally dry and hot conditions (RH < 21%, T > 37 °C) we observed strong deviations from Craig-Gordon predicted isotope enrichments caused by partial stomatal closure. The atmospheric-leaf vapour pressure relationship is also a strong predictor of the observed leaf cellulose δ18O values across one aridity gradient. Our finding supports a wider applicability of leaf cellulose δ18O composition as a climate proxy for atmospheric humidity conditions during the leaf growing season than previously documented.

Rehabilitation after treatment for jugular foramen lesions.

Swallowing problems following jugular foramen surgery are more common than is often acknowledged and affect up to a third of our patients. They have a significant effect on quality of life. We have become more proactive in this respect and anticipate these problems before they become established. In this article we present our management protocol that has evolved over the past 30 years as a result of our experience treating 134 glomus jugulare tumors. Our current protocol involves a thorough preoperative assessment of swallowing. After jugular foramen surgery, patients undergo further evaluation using fiberoptic endoscopic evaluation of swallowing (FEES), videofluoroscopy, and manometry. Those with prolonged or poorly compensated dysphagia are offered rehabilitation surgery. We describe this technique, which has proved beneficial to our patients. Guidelines for management are proposed.

Understanding the chemical vapor deposition of diamond: recent progress.

In this paper we review and provide an overview to the understanding of the chemical vapor deposition (CVD) of diamond materials with a particular focus on the commonly used microwave plasma-activated chemical vapor deposition (MPCVD). The major topics covered are experimental measurements in situ to diamond CVD reactors, and MPCVD in particular, coupled with models of the gas phase chemical and plasma kinetics to provide insight into the distribution of critical chemical species throughout the reactor, followed by a discussion of the surface chemical process involved in diamond growth.

Incontinence after brain injury: prevalence, outcome and multidisciplinary management on a neurological rehabilitation unit.

OBJECTIVE: To investigate the prevalence, outcome and multidisciplinary management of incontinence in patients with acquired brain injury. DESIGN: Retrospective case notes review. SETTING: Regional neurological rehabilitation unit. SUBJECTS: Two hundred and thirty-eight patients with acquired brain injury. MAIN MEASURES: Bladder and bowel subscores of the Barthel Index and Functional Independence Measure; number of multidisciplinary goals addressing bladder and bowel function. RESULTS: Fifty per cent of patients (n=112) had impaired bladder or bowel subscores on admission. Significant improvement was seen at discharge but 36% of patients (n=77) still had some degree of impairment. Over 90% of patients were set multidisciplinary goals addressing self-care (n=213) and mobility (n=205) but only 3.5% (n=8) were set multidisciplinary goals addressing bladder and bowel function. CONCLUSIONS: Incontinence was common in patients with brain injury on a neurological rehabilitation unit. Significant improvement was seen following rehabilitation. Bladder and bowel management was not well incorporated into the multidisciplinary management process.

Application of a quantum cascade laser for time-resolved, in situ probing of CH4/H2 and C2H2/H2 gas mixtures during microwave plasma enhanced chemical vapor deposition of diamond.

First illustrations of the utility of pulsed quantum cascade lasers for in situ probing of the chemistry prevailing in microwave plasma activated hydrocarbon/Ar/H2 gas mixtures used for diamond thin film growth are reported. CH4 and C2H2 molecules, and their interconversion, have been monitored by line-of-sight single pass absorption methods, as a function of process conditions (e.g., choice of input hydrocarbon (CH4 or C2H2), hydrocarbon mole fraction, total gas pressure, and applied microwave power). The observed trends can be rationalized, qualitatively, within the framework of the previously reported modeling of the gas-phase chemistry prevailing in hot filament activated hydrocarbon/H2 gas mixtures (Ashfold et al. Phys. Chem. Chem. Phys. 2001, 3, 3471). Column densities of vibrationally excited C2H2(v5=1) molecules at low input carbon fractions are shown to be far higher than expected on the basis of local thermodynamic equilibrium. The presence of vibrationally excited C2H2 molecules (C2H2(double dagger)) can be attributed to the exothermicity of the C2H3 + H <==> C2H2 + H2 elementary reaction within the overall multistep CH4 --> C2H2 conversion. Diagnostic methods that sample just C2H2(v=0) molecules thus run the risk of underestimating total C2H2 column densities in hydrocarbon/H2 mixtures operated under conditions where the production rate of C2H2(double dagger) molecules exceeds their vibrational relaxation (and thermal equilibration) rates.

Lateralisation of striatal function: evidence from 18F-dopa PET in Parkinson's disease.

OBJECTIVES: The aetiology of the cognitive changes seen in Parkinson's disease (PD) is multifactorial but it is likely that a significant contribution arises from the disruption of dopaminergic pathways. This study aimed to investigate the contribution of the dopaminergic system to performance on two executive tasks using (18)F-6-fluorodopa positron emission tomography ((18)F-dopa PET) in PD subjects with early cognitive changes. METHODS: 16 non-demented, non-depressed PD subjects were evaluated with the Tower of London (TOL) spatial planning task, a verbal working memory task (VWMT) and (18)F-dopa PET, all known to be affected in early PD. Statistical parametric mapping (SPM) localised brain regions in which (18)F-dopa uptake covaried with performance scores. Frontal cortical resting glucose metabolism was assessed with (18)F-fluoro-2-deoxy-D-glucose ((18)F-FDG) PET. RESULTS: SPM localised significant covariation between right caudate (18)F-dopa uptake (Ki) and TOL scores and between left anterior putamen Ki and VWMT performance. No significant covariation was found between task scores and (18)F-dopa Ki values in either limbic or cortical regions. Frontal cortical glucose metabolism was preserved in all cases. CONCLUSIONS: These findings support a causative role of striatal dopaminergic depletion in the early impairment of executive functions seen in PD. They suggest that spatial and verbal executive tasks require integrity of the right and left striatum, respectively, and imply that the pattern of cognitive changes manifest by a patient with PD may reflect differential dopamine loss in the two striatal complexes.

Pitch change in male-to-female transsexuals: has phonosurgery a role to play?

Male-to-female transsexuals, who have undergone gender reassignment surgery, may continue to have low pitched voices. Voice therapy may assist them to use their voice in a manner more likely to be perceived as female but, if this approach is unsuccessful, a laryngeal framework operation may be necessary to raise vocal pitch. This study assessed the effects of crico-thyroid approximation surgery in 14 transsexuals. Modal pitch was significantly increased by surgery but with substantial variation across speakers. Modal pitch was significantly correlated with judgements of gender by speech and language therapists who listened to tapes of the subjects. The results suggest that crico-thyroid approximation may be used to raise the pitch of voices of male-to-female transsexuals. Further research is needed to clarify the reasons for the variability in outcome, to monitor the longer-term changes in voice and the impact for clients of their modified voice in real life situations.

Juvenile angiofibroma: the lessons of 20 years of modern imaging.

Seventy-two patients with juvenile angiofibroma have been investigated by computerized tomography (CT) and/or magnetic resonance imaging (MRI) over a period of 20 years. The evidence from these studies indicates that angiofibroma takes origin in the pterygo-palatine fossa at the aperture of the pterygoid (vidian) canal. An important extension of the tumour is posteriorly along the pterygoid canal with invasion of the cancellous bone of the pterygoid base, and greater wing of the sphenoid (60 per cent of patients). Distinctive features of angiofibroma are the high recurrence rate, and the rapidity with which many tumours recur. It is postulated that the principal determinant of recurrence is a high tumour growth rate at the time of surgery coupled with incomplete surgical excision. The inability to remove the tumour in toto is principally due to deep invasion of the sphenoid, as described above. In this series 93 per cent of recurrences occurred with this type of tumour extension. A contributory cause in these patients is the use of pre-operative embolization. The treatment implications of these findings are examined.

Craniofacial resection for tumors of the nasal cavity and paranasal sinuses--a 17-year experience.

BACKGROUND: The rarity of sinonasal tumors has precluded long-term follow-up of large series of craniofacial resections until now. METHODS: A series of 209 patients suffering from a wide range of histologies who had undergone craniofacial resection for sinonasal neoplasia with up to 17 years' follow-up were analyzed. RESULTS: An overall actuarial survival of 51% at 5 years and 41% at 10 years was found for the cohort as a whole. For malignant tumors, the 5-year actuarial survival was 44%, falling to 32% at 10 years. For benign pathology, the actuarial survival was 75% at both 5 and 10 years. Statistical analysis identified three factors which significantly affect outcome and survival: malignant histology, brain involvement, and orbital involvement. Few complications are associated with the surgery, with the mean post-operative stay being 16 days. CONCLUSIONS: The improved survival and minimal morbidity and mortality associated with craniofacial resection make it the optimum approach to sinonasal tumors.

A skull base extradural hypoglossal neurilemmoma resected via an extended posterolateral approach.

The case of a 43-year-old man with a right skull base hypoglossal neurilemmoma excised via the extended posterolateral approach is presented. There is only one previous case of hypoglossal neurilemmoma in the literature. The surgical technique described is a new approach to the posterior skull base involving a suboccipital craniectomy, mastoidectomy and the removal of the lateral process of the atlas. It provides an inferior approach to the jugular foramen and hypoglossal canal that allows the lower cranial nerves to be identified as they exit from their skull base foramina. In the discussion we compare this technique to other surgical approaches previously described for access to the region of the jugular foramen.

Metastatic carcinoma of the temporal bone presenting as glomus jugulare and glomus tympanicum tumours: a description of two cases.

Two cases of metastatic carcinoma of the temporal bone, that simulated glomus tumours on thorough preoperative evaluation are described. Although rare, metastatic spread to this area is recognized, but presentation in this way is unique.

Inspiratory coactivation of the genioglossus enlarges retroglossal space in laryngectomized humans.

To investigate the relationship between the electrical activity of the genioglossus (GG-EMG) and associated tongue movement, seven laryngectomized subjects breathing through a tracheal stoma (without pressure or flow change in the upper airway) were studied in the supine position. Tongue movement, with the use of lateral fluoroscopy, and GG-EMG expressed as a percentage of maximum voluntary genioglossal activation were monitored simultaneously during 1) spontaneous inspiration (SI), 2) resistive loaded inspiration (LI), and 3) rapid inspiration (RI). Tongue position during each maneuver was compared with its position during spontaneous expiration. Peak GG-EMG during the three maneuvers was significantly different from each other (SI: 5.4 +/- 1.6, LI: 11.9 +/- 1.8, and RI: 51.6 +/- 9.4 (SE) %, respectively). Associated forward movement of the posterior aspect of the tongue was minimum during SI; however, significant movement was observed during LI, and this was increased during RI. Significant covariance existed between peak GG-EMG and this movement. Genioglossal coactivation with inspiration enlarges the glossopharyngeal airway, particularly in its caudal part. In subjects with intact upper airways, this activation may protect or enhance upper airway patency in an effort-dependent manner.

Enhanced magnetic resonance imaging and subtraction techniques in postoperative evaluation of craniofacial resection for sinonasal malignancy.

The use of magnetic resonance imaging (MRI) enhanced with gadolinium. and diethylenetriamine pentaacetic acid (DTPA) in the preoperative evaluation of sinonasal malignancy is well established and has an accuracy of over 98%. Since 1979, 208 patients have undergone craniofacial resection at London's Institute of Laryngology & Otology, primarily for sinonasal neoplasia affecting the anterior skull base. Thirty-five "high-risk" patients had MRI at follow-up. The MRI scans were assessed before the patients were examined under anesthesia. MRI was assessed before examination under anesthesia and the results compared with histologic findings demonstrating a reasonable degree of positive correlation but one which is inferior to that found preoperatively (80%). An extension of this technique using the subtraction of T1-weighted MRI with Gd-DTPA highlights areas of increased vascularity, which significantly improves the ability to predict recurrence at the skull base and above the surgical repair in the anterior cranial fossa (94%).

Metastatic adenocarcinoma of the ethmoids in a patient with previous gastric adenocarcinoma: a case report.

Metastatic carcinoma of the ethmoids is very rare. Of the few cases reported in the literature, the majority are renal in origin. Although metastases from the gastrointestinal tract have been reported, there are no known cases of metastases from the stomach. We present a rare case of metastatic adenocarcinoma of the ethmoids in a patient previously treated for adenocarcinoma of the stomach and describe the possible mechanisms of spread. The patient had a craniofacial resection of the tumour but unfortunately died four weeks post-operatively from acute liver failure probably caused by a liver metastasis.

Laryngeal papillomatosis with subsequent development of papillomata in the paranasal sinuses--is it seeding by intubation?

Concern has been expressed regarding the seeding of viral DNA, in laryngeal papillomatosis, to other sites in the respiratory tract during treatment. Controversy exists regarding the concept of seeding by the laser plume. However, instrumentation and anaesthetic intubation are also strongly implicated in seeding DNA to the proximal respiratory tract. No cases of recurrent laryngeal papillomatosis and subsequent papilloma in the paranasal sinuses have been reported.

Iodine seeds in the treatment of slowly proliferating tumours in the head and neck region.

Locally recurrent/persistent disease is a major cause of morbidity and mortality in patients suffering from tumours arising in the head and neck region. Iodine-125, with its long half-life of 60 days, is particularly suited for the treatment of slowly proliferating tumours (e.g. adenoidcystic carcinomas) of this site. We report our experience with 18 patients using iodine-125 seeds, placed at the time of surgery in patients with such tumours. Eleven of the patients were treated for recurrent disease following previous radical treatment. Disease free survival was 89% at 2 years and 53% at 5 years after treatment. These results are encouraging in a group of patients in whom achieving and maintaining local control can be extremely difficult.

Cordectomy: a solution to Teflon granuloma of the vocal fold.

Teflon injection has been widely used for the treatment of unilateral vocal fold paralysis. Complications are few and infrequent. Overinjection and Teflon granuloma are the two commonest problems encountered. Treating such complications and restoring vocal quality is widely regarded as difficult. Endoscopic transmucosal excision of the excess Teflon and/or granuloma has not been successful in improving phonatory quality. Cordectomy is proposed as an alternative surgical approach for managing both the convex vocal fold and Teflon granuloma after injection.

An unusual complication of glomus jugulare tumour resection: a case report and literature review.

A 47-year-old man presented, in 1990, with a short history of left-sided cerebellar ataxia. In 1986 he had undergone excision of a glomus jugulare tumour. A magnetic resonance (MRI) scan demonstrated cerebellar herniation through a defect in his skull base. Surgical repair was undertaken with resolution of his symptoms.

The 'Allan Johnson' voice prosthesis. A modification of the Bivona voice prosthesis for immediate post-fitting aphonia after secondary tracheo-oesophageal puncture.

The combination of a narrow oesophageal lumen and a hypertonic pharyngo-oesophageal (P-E) segment following laryngectomy and secondary tracheo-oesophageal puncture (TEP) can cause obstruction of a voice prosthesis and consequently prevent phonation. The 'Allan Johnson' modification of the Bivona voice prosthesis incorporates a stainless steel slide and has been successfully used to remedy such a circumstance.