bluuebunny/crossref_metadata_2025 huggingface dataset:
Variations in fluid activity across the Etive thermal aureole, Scotland: evidence from cordierite volatile contents
Authors: RIGBY M. J. , DROOP G. T. R. , BROMILEY G. D.
Published: February 2008

The H2O and CO2 content of cordierite was analysed in 34 samples from successive contact metamorphic zones of the Etive thermal aureole, Scotland, using Fourier‐transform infrared spectroscopy (FTIR). The measured volatile contents were used to calculate peak metamorphic H2O and CO2 activities. Total volatile contents are compared with recently modelled cordierite volatile saturation surfaces in order to assess the extent of fluid‐present v. fluid‐absent conditions across the thermal aureole. In the middle aureole, prior to the onset of partial melting, calculated aH2O values are high, close to unity, and measured volatile contents intersect modelled H2O–CO2 saturation curves at the temperature of interest, suggesting that fluid‐present conditions prevailed. Total volatile contents and aH2O steadily decrease beyond the onset of partial melting, consistent with the notion of aH2O being buffered to lower values as melting progresses once free hydrous fluid is exhausted. All sillimanite zone samples record total volatile contents that are significantly lower than modelled H2O–CO2 saturation surfaces, implying that fluid‐absent conditions prevailed. The lowest recorded aH2O values lie entirely within part of the section where fluid‐absent melting reactions are thought to have dominated. Samples within 30 m of the igneous contact appear to be re‐saturated, possibly via a magmatically derived fluid. In fluid‐absent parts of the aureole, cordierite H2O contents yield melt–H2O contents that are compatible with independently determined melt–H2O contents. The internally consistent cordierite volatile data and melt–H2O data support the conclusion that the independent P–T estimates applied to the Etive rocks were valid and that measured cordierite volatile contents are representative of peak metamorphic values. The Etive thermal aureole provides the most compelling evidence, suggesting that the cordierite fluid monitor can be used to accurately assess the fluid conditions during metamorphism and partial melting in a thermal aureole.
Separated by a Common Language? Entrepreneurship Research across the Atlantic
Authors: Brush Candida G. , Manolova Tatiana S. , Edelman Linda F.
Published: February 2008

While recent inventories and assessments of the entrepreneurship field examine the focus, purpose, and methods, one area receiving less attention is the outcome or dependent variable. The outcome variable is of critical importance in scholarship, as it is a leading indicator of the cumulative nature of the scholarship in our field. This paper reviews 389 articles published over the past 3 years in four top entrepreneurship journals; two published in the United States and two published in Europe. It classifies the scholarship by theoretical underpinnings, independent variables, dependent variables, and then looks at the variation in these by origin of the journal. Results indicate that entrepreneurship researchers are using a wide variety of dependent variables, that the most popular unit of analysis is the firm, and that performance, broadly defined, is the most popular dependent variable. Implications for future research are discussed.
Nordic Entrepreneurship Research
Authors: Hjorth Daniel
Published: February 2008

This article describes and discusses Nordic entrepreneurship research (NER). It does so by providing a broader context for conducting entrepreneurship research, including historical, sociocultural, and disciplinary elements substantiating an understanding of “Nordic.” Contextualizing NER this way, we attempt for the article to do what it says, i.e., to also write here in a style we argue is characteristically Nordic. This includes a priority to the local and particular, and a subsequent focus on questions resonant with nominalist research. We thereby enable an experience of NER as a cultural practice, as we argue that this is a crucial part of understanding what it is. Drawing on a tracing of NER in journal publications (in between 2001 and 2005), the article identifies trends and tendencies. We identify three generations of entrepreneurship research and suggest directions for the future development of the third. This way, the discussion and conclusions are drawn toward images of what a Nordic entrepreneurship research might become.
Irs4p and Tax4p: Two Redundant EH Domain Proteins Involved in Autophagy
Authors: Bugnicourt Amandine , Mari Muriel , Reggiori Fulvio , Haguenauer‐Tsapis Rosine , Galan Jean‐Marc
Published: February 2008

Proteins carrying EPS15 homology (EH) domains are present from yeast to mammals. The characterized members of this protein family are all involved in intracellular trafficking, typically endocytosis and endocytic recycling. We focused on two members of this family in Saccharomyces cerevisiae Irs4p and Tax4p, whose functions are less well characterized. We show that the deletion of IRS4 altered the function of a neighboring gene, VPS51, involved in endocytic recycling. The irs4Δtax4Δ cells complemented for the loss of Vps51p (irs4Δtax4Δ*) display no defects in endocytosis and endosomal recycling, clearly differentiating these two EH proteins from the other protein family members. Because Irs4p is phosphorylated when autophagy is induced, we studied the potential role of these two proteins in this latter process. We observed a loss of viability upon starvation in irs4Δtax4Δ* cells because of a delay in bulk autophagy. Irs4p and Tax4p are also required for pexophagy but not for the cytoplasm‐to‐vacuole pathway. In growing cells, Irs4p and Tax4p colocalized to few cytoplasmic puncta distinct from endosomes and Golgi compartments. In conditions inducing autophagy, Irs4p and Tax4p partially localized to the pre‐autophagosomal structure (PAS) and are required to efficiently recruit to the PAS Atg17p, a factor modulating the autophagic response. We propose that Irs4p and Tax4p are two redundant modulators of the autophagic processes acting upstream from Atg17p, possibly in the signaling events leading to the activation of the autophagic machinery in response to starvation.
ORIGINAL ARTICLE: Decreased Factor XII Activity is Associated with Recurrent IVF‐ET Failure
Authors: Matsubayashi Hidehiko , Sugi Toshitaka , Suzuki Takahiro , Uchida Noa , Atsumi Haruyo , Izumi Shun‐ichiro , Mikami Mikio
Published: February 2008

Problem

A decrease in factor XII (FXII) activity has been observed in women with unexplained recurrent miscarriages. Because of the many similarities between recurrent in vitro fertilization‐embryo transfer (IVF‐ET) failure and early pregnancy loss patients, we investigated whether women with recurrent IVF‐ET failure had low FXII activity.

Method of study

Blood from 110 patients with three or more IVF‐ET failures was tested for FXII activity, autoantibodies and other coagulation parameters. These patients were compared with 191 recurrent miscarriage patients, 87 controls. FXII activity was measured by an activated partial thromboplastin time (APTT) assay.

Results

Factor XII activity of the IVF‐ET failure group (median 79.5, range 37–150) was significantly lower than that of control group (median 109, range 35–225, P < 0.001 by Mann–Whitney test) or that of recurrent pregnancy loss (RPL)group (median 92, range 20–205). The FXII activity of IVF‐ET failure patients was positively correlated with age, but not associated with the number of IVF‐ET failures, infertile duration, autoantibodies, or other coagulation parameters.

Conclusion

Decreased FXII activity may causally relate to reproductive failure.
The link between periodontal disease and cardiovascular disease is probably inflammation
Authors: Davé S , Van Dyke TE
Published: February 2008

A periodontal–cardiovascular relationship has been postulated for several years but a definitive etiologic relationship has not been established. However, evidence continues to accumulate epidemiologic and otherwise that periodontitis at the very least plays a contributory role in the progression of cardiovascular disease. This paper will argue if indeed such a causative relationship exists, it is most likely based on the incremental contribution of chronic periodontal inflammation on systemic inflammation rather than the direct colonization of atherosclerotic plaques with periodontal pathogens.
The influence of dust formation modelling on Na i and K i line profiles in substellar atmospheres
Authors: Johnas C. M. S. , Helling Ch. , Dehn M. , Woitke P. , Hauschildt P. H.
Published: February 2008

We aim to understand the correlation between cloud formation and alkali line formation in substellar atmospheres. We perform line profile calculations for Na i and K i based on the coupling of our kinetic model for the formation and composition of dust grains with 1D radiative transfer calculations in atmosphere models for brown dwarfs and giant gas planets. The Na i and K i line profiles sensibly depend on the way clouds are treated in substellar atmosphere simulations. The kinetic dust formation model results in the highest pseudo-continuum compared to the limiting cases.
Flow‐mediated dilation and exercise‐induced hyperaemia in highly trained athletes: comparison of the upper and lower limb vasculature
Authors: Walther G. , Nottin S. , Karpoff L. , Pérez‐Martin A. , Dauzat M. , Obert P.
Published: February 2008

Aim:  The main purpose of the present study was to assess whether similar vascular adaptive changes could be obtained by long‐term intensive training involving predominantly either the lower or the upper limb musculature.

Methods:  In 11 cyclists (C), 10 swimmers (S) and 10 sedentary controls (Sed), duplex Doppler ultrasonography was used to measure post‐occlusion endothelium‐dependent flow‐mediated dilation (FMD), endothelium‐independent, glycerine trinitrate‐induced dilation (GTND) and exercise‐induced blood flow changes in the arm (axillary artery) and leg (superficial femoral artery). Limb‐specific exercise was achieved by one elbow‐flexion or one leg‐extension maximal exercise test, thereby allowing assessment of upper and lower limb muscle perfusion, vascular conductance and vasodilatory capacity of resistance vessels during effort.

Results:  C and S exhibited vascular remodelling associated with improved FMD and GTND in the predominantly trained limbs compared to Sed. Both showed greater muscle perfusion and vascular conductance than Sed during isolated exercise involving the predominantly trained musculature. C showed also higher FMD in the brachial artery and greater peak muscle perfusion and conductance in the non‐exercising muscles, whereas S presented only enhanced FMD in the superficial femoral artery.

Conclusion:  Therefore, in the upper as well as in the lower limb vasculature, repetitive exposure to increased shear stress over a long‐term period results in improved FMD of large conduit arteries as well as greater vasodilatory capacity during isolated exercise in the predominantly trained muscles. Long‐term training involving predominantly the lower limbs also results in enhanced vascular reactivity in upper limb conduit and resistance vessels.
Avoidance of BIPP allergy hypersensitivity reactions following ear surgery
Authors: Bennett A.M.D. , Bartle J. , Yung M.W.
Published: February 2008

Keypoints

• Bismuth Iodoform Paraffin Paste (BIPP) is one of the most commonly used packs after middle and external ear surgery.

• Only two retrospective case studies exist which found a 0.4% and 6% overall risk of BIPP allergy.

• The result of our prospective patch testing study identifies the true incidence of BIPP allergy to be 12% in those previously exposed and 1% in those not previously exposed.

• The component part responsible is iodoform not iodine.

• We recommend patch testing patients previously exposed to BIPP undergoing ear surgery, if postoperative BIPP packing is being considered.

• We recommend those patients allergic to BIPP should be tested with its constituent parts for future reference. It is important to determine whether there is allergy to iodine solution or not as this would preclude them from future iodine solution contrast studies and iodine solution skin prep before surgery.

• We do not recommend testing patients not previously known to be exposed to BIPP as the incidence of allergy is low and there exists a risk of sensitization.
PET/CT for assessing mandibular invasion by intraoral squamous cell carcinomas
Authors: Babin E. , Desmonts C. , Hamon M. , Bénateau H. , Hitier M.
Published: February 2008

Keypoints

• Evaluation of mandible invasion in cancer of the oral cavity and oropharynx is a major challenge.

• Today, CT scans are the most frequent imaging technique used, with sensitivity of 53 to 92% and specificity of 83 to 96%.

• Positron emission tomography is known as one of the most sensitive imaging techniques for head and neck cancer, but has poor anatomical resolution.

• Our study associates positron emission tomography with CT scans, fusioning both images to maximise data information.

• Positron emission tomography/CT fusion shows sensitivity of 100% with specificity of 85%. This result encourages the use of positron emission tomography/CT when assessing mandibular invasion.
Does flexible videostroboscopy compare with rigid videostroboscopy in the assessment of the neoglottis? A preliminary report
Authors: Singh A. , Kazi R. , Venkitaraman R. , Kapoor K. , Nutting C. , Clarke P. , Rhys Evans P. , Harrington K.
Published: February 2008

Objective:  To evaluate rigid and flexible stroboscopy of the neoglottis.

Study design:  Prospective pilot study set at a tertiary level Head & Neck Unit.

Participants:  Twenty‐four patients recruited. All had undergone a total laryngectomy and were voicing using a Blom‐singer valve. All had stroboscopic evaluation of their neoglottis using flexible and rigid endoscopes.

Main outcome measures:  A rating form was devised based on six parameters with clear definitions. Secondary measures included ability to tolerate the procedure and completeness of the rating form for each parameter using the two systems.

Results:  There was good reliability between individual raters for the assessment of each system based on Spearman Rho correlation. Importantly, two‐thirds of the patients were unable to tolerate the rigid videostroboscopy managed flexible videostroboscopy. Correlation between rigid and flexible videostroboscopy was poor for both raters. Flexible systems picked up more mucosal waves and allowed further analysis of the mucosal wave pattern.

Conclusions:  To our knowledge, this is the first study to demonstrate that fibreoptic videstroboscopy is as good as rigid videostroboscopy in the assessment of the neoglottis. In fact, flexible videostroboscopy should be routinely used, as it is better tolerated and allows a more detailed analysis of the neoglottis.
Out‐patient management of patients with a peritonsillar abscess
Authors: Al Yaghchi C. , Cruise A. , Kapoor K. , Singh A. , Harcourt J.
Published: February 2008

Keypoints

• In the United Kingdom, patients with a peritonsillar abscess are usually managed as inpatients. However, studies in other countries have shown successful management of these patients as outpatients.

• We designed an evidence based protocol for the management of patients with a peritonsillar abscess. Diagnosis was by aspiration of pus. Initial treatment was with analgesia, 1.2 g co‐amoxiclav and 4 mg dexamethasone intravenously.

• Data were collected prospectively over 11 months on the management of all patients who had been confirmed by aspiration of pus to have a peritonsillar abscess.

• Four of the 46 patients (9%) treated as per the protocol required admission, two immediately and two later on. Of the 44 patients initially treated as outpatients, 41 said they were happy to have been treated as outpatients and not admitted to hospital (93%).

• Patients with a peritonsillar abscess can be managed successfully as outpatients with a high degree of patient satisfaction.
Endoscopic minimal access surgery in nasal and sinus tumours: lessons from initial experience
Authors: Ali S. , McGarry G.W.
Published: February 2008

Keypoints

• The role of endoscopic techniques in the treatment of Nose and Para‐Nasal Sinus tumours is the subject of wide debate.

• Technical advances in skills, imaging and instrumentation have resulted in Endoscopic Minimal Access Surgery gaining wide acceptance in the treatment of benign tumours. The place of endoscopes in malignant disease is more controversial.

• Defining the aims of endoscopic surgery is key to achieving a successful outcome.

• Experience with these new technologies and strategies should be gathered in a Clinical Network and Multi‐Disciplinary Team setting, with planned long‐term follow up.

• We report our initial experience of 33 patients managed with EMAS (27 curative, six debulking/palliative cases).

• Initial experience of the transition from the benign to malignant arenas supports a continued, cautious, structured evaluation of the endoscopic approach.
Nasopharyngeal cancer incidence and survival in Scotland, 1975–2001
Authors: Anandan C. , Elton R. , Hitchings A. , Brewster D.H.
Published: February 2008

Objectives: To investigate trends in the incidence of, and survival from, nasopharyngeal cancer in Scotland during the period 1975–2001.

Design: Descriptive epidemiological study.

Setting: Scotland.

Participants: The anonymised records of 556 patients diagnosed with nasopharyngeal cancer (ICD‐9 147; ICD‐10 C11) in Scotland between 1975 and 2001, and held on the Scottish Cancer Registry.

Main outcome measures: Incidence rates, and relative survival at 1, 3 and 5 years for defined age groups and time periods.

Results: There was no clear trend in age‐standardised incidence rates of nasopharyngeal cancer throughout the study period, although age‐specific incidence rates do suggest a downward trend among older age groups, especially in men. The trend in incidence with deprivation was significant for both males (P = 0.011) and females (P = 0.004). Survival from nasopharyngeal cancer has improved for all age groups over time, although survival still decreases with age. In the 15–44 age group, 5 year relative survival was 84% in patients diagnosed during 1995–2001 compared to 46% in those diagnosed during 1975–1979. Survival was higher among patients from the most affluent quintile (P = 0.004).

Conclusions: In Scotland, age‐standardised incidence rates of nasopharyngeal cancer have remained relatively stable over the last 25 years. Survival has improved across all age groups in recent years, but is higher in younger patients, and in residents of the most affluent socio‐ economic areas.
Turner syndrome and the evolution of human sexual dimorphism
Authors: Crespi Bernard
Published: February 2008

Turner syndrome is caused by loss of all or part of an X chromosome in females. A series of recent studies has characterized phenotypic differences between Turner females retaining the intact maternally inherited versus paternally inherited X chromosome, which have been interpreted as evidence for effects of X‐linked imprinted genes. In this study I demonstrate that the differences between Turner females with a maternal X and a paternal X broadly parallel the differences between males and normal females for a large suite of traits, including lipid profile and visceral fat, response to growth hormone, sensorineural hearing loss, congenital heart and kidney malformations, neuroanatomy (sizes of the cerebellum, hippocampus, caudate nuclei and superior temporal gyrus), and aspects of cognition. This pattern indicates that diverse aspects of human sex differences are mediated in part by X‐linked genes, via genomic imprinting of such genes, higher rates of mosaicism in Turner females with an intact X chromosome of paternal origin, karyotypic differences between Turner females with a maternal versus paternal X chromosome, or some combination of these phenomena. Determining the relative contributions of genomic imprinting, karyotype and mosaicism to variation in Turner syndrome phenotypes has important implications for both clinical treatment of individuals with this syndrome, and hypotheses for the evolution and development of human sexual dimorphism.
Asthmatics able to step down from inhaled corticosteroid treatment without loss of asthma control have low serum eotaxin/CCL11
Authors: Hoffmann Hans Jürgen , Nielsen Lars Peter , Harving Henrik , Heinig John H. , Dahl Ronald
Published: February 2008

Introduction:  The addition of a long‐acting β2 agonist (LABA) to inhaled corticosteroid (ICS) may control asthma better than ICS alone. Eosinophil markers may predict symptom severity in asthma.

Objectives:  The effect of combination treatment on moderate to severe asthmatics not selected to respond rapidly to steroid deprivation was compared with monotherapy. The ability of serum markers to predict symptom severity was assessed.

Methods:  Asthmatics treated adequately with ICS (750–1000 mcg ICS daily) were randomised to receive ICS (fluticasone propionate) + LABA (salmeterol) (500 mcg/50 mcg bd) or ICS alone (500 mcg bd). If asthma was controlled at clinic visits every 6 weeks, ICS dose was tapered until asthma exacerbated (hospitalisation, ICS above study medication, peak flow variation, decline in forced expiratory volume in 1 s and/or use of rescue medication), or placebo was maintained for 6 weeks. Efficacy of the treatments was compared. Serum cytokines and chemokines were compared among the groups reporting severe, mild or no symptoms.

Results:  There was no difference between the treatment arms in the clinical analysis. Nine patients could be maintained on placebo for 6 weeks, 36 developed mild symptoms and 16 developed severe symptoms. Patients on placebo for 6 weeks had significantly lower serum eotaxin at baseline than patients with symptoms. Patients with mild symptoms had intermediate serum eotaxin concentrations.

Conclusion:  Patients with asthma controlled on ICS respond heterogeneously to ICS tapering. Serum eotaxin/CCL11 may be useful in predicting the severity of symptoms patients develop during steroid tapering and should be evaluated in guiding asthma treatment.

Please cite this paper as: Hoffmann HJ, Nielsen LP, Harving H, Heinig JH and Dahl R. Asthmatics able to step down from inhaled corticosteroid treatment without loss of asthma control have low serum eotaxin/CCL11. The Clinical Respiratory Journal 2008; 2: 149–157.
Transgenerational effects of prenatal nutrient restriction on cardiovascular and hypothalamic‐pituitary‐adrenal function
Authors: Bertram Caroline , Khan Omar , Ohri Sunil , Phillips David I. , Matthews Stephen G. , Hanson Mark A.
Published: February 2008

The perinatal environment is a powerful determinant of risk for developing disease in later life. Here, we have shown that maternal undernutrition causes dramatic changes in heart structure and hypothalamo‐pituitary‐adrenal (HPA) function across two generations. Pregnant guinea pigs were fed 70% of normal intake from gestational days 1–35 (early restriction; ER), or 36–70 (late restriction; LR). Female offspring (F1) were mated and fed ad libitum to create second generation (F2) offspring. Heart morphology, blood pressure, baroreceptor and HPA function were assessed in male F1 and F2 offspring. ERF1 males exhibited elevated blood pressure, increased left ventricular (LV) wall thickness and LV mass. These LV effects were maintained in the ERF2 offspring. Maternal undernutrition increased basal cortisol and altered HPA responsiveness to challenge in both generations; effects were greatest in LR groups. In conclusion, moderate maternal undernutrition profoundly modifies heart structure and HPA function in adult male offspring for two generations.
Simulated apnoeas induce serotonin‐dependent respiratory long‐term facilitation in rats
Authors: Mahamed Safraaz , Mitchell Gordon S.
Published: February 2008

Long‐term facilitation (LTF) is a form of respiratory neuroplasticity frequently induced by acute intermittent isocapnic hypoxia (AIH, three 5 min isocapnic hypoxic episodes). Although repetitive apnoeas are a frequent natural occurrence producing brief (< 30 s) episodes of hypoxia and hypercapnia, it is unknown if repetitive apnoeas also elicit LTF. Apnoea‐induced LTF may preserve upper airway patency during sleep, thereby limiting further apnoeic events. We tested the hypothesis that repeated, brief ventilator‐induced apnoeas are sufficient to induce serotonin‐dependent phrenic and hypoglossal (XII) LTF in anaesthetized rats. Anaesthetized, male Sprague–Dawley rats were exposed to three or six 25 s ventilator apnoeas with 5 min intervals, and compared to time control and AIH‐treated rats. Three and six ventilator apnoeas induced phrenic and XII LTF with a magnitude similar to AIH. Both apnoea‐induced and AIH‐induced LTF were associated with a decreased CO2 recruitment threshold for phrenic and XII activity (∼4 mmHg). Spinal methysergide, a serotonin receptor antagonist, blocked apnoea‐induced LTF but not changes in the CO2‐recruitment threshold. Thus, brief ventilator apnoeas elicit phrenic and XII LTF. Similar to AIH‐induced LTF, apnoea‐induced LTF is serotonin dependent, and the relevant serotonin receptors for phrenic LTF are located in the cervical spinal cord. Apnoea‐induced LTF may have implications for the maintenance of breathing stability, particularly during sleep.
Exercise induces expression of leukaemia inhibitory factor in human skeletal muscle
Authors: Broholm Christa , Mortensen Ole Hartvig , Nielsen Søren , Akerstrom Thorbjorn , Zankari Alaa , Dahl Benny , Pedersen Bente Klarlund
Published: February 2008

The leukaemia inhibitory factor (LIF) belongs to the interleukin (IL)‐6 cytokine superfamily and is constitutively expressed in skeletal muscle. We tested the hypothesis that LIF expression in human skeletal muscle is regulated by exercise. Fifteen healthy young male volunteers performed either 3 h of cycle ergometer exercise at ∼60% of (n= 8) or rested (n= 7). Muscle biopsies were obtained from the vastus lateralis prior to exercise, immediately after exercise, and at 1.5, 3, 6 and 24 h post exercise. Control subjects had biopsy samples taken at the same time points as during the exercise trial. Skeletal muscle LIF mRNA increased immediately after the exercise and declined gradually during recovery. However, LIF protein was unchanged at the investigated time points. Moreover, we tested the hypothesis that LIF mRNA and protein expressions are modulated by calcium (Ca2+) in primary human skeletal myocytes. Treatment of myocytes with the Ca2+ ionophore, ionomycin, for 6 h resulted in an increase in both LIF mRNA and LIF protein levels. This finding suggests that Ca2+ may be involved in the regulation of LIF in endurance‐exercised skeletal muscle. In conclusion, primary human skeletal myocytes have the capability to produce LIF in response to ionomycin stimulation and LIF mRNA levels increase in skeletal muscle following concentric exercise. The finding that the increase in LIF mRNA levels is not followed by a similar increase in skeletal muscle LIF protein suggests that other exercise stimuli or repetitive stimuli are necessary in order to induce a detectable accumulation of LIF protein.
Motor unit recruitment in human biceps brachii during sustained voluntary contractions
Authors: Riley Zachary A. , Maerz Adam H. , Litsey Jane C. , Enoka Roger M.
Published: February 2008

The purpose of the study was to examine the influence of the difference between the recruitment threshold of a motor unit and the target force of the sustained contraction on the discharge of the motor unit at recruitment. The discharge characteristics of 53 motor units in biceps brachii were recorded after being recruited during a sustained contraction. Some motor units (n= 22) discharged action potentials tonically after being recruited, whereas others (n= 31) discharged intermittent trains of action potentials. The two groups of motor units were distinguished by the difference between the recruitment threshold of the motor unit and the target force for the sustained contraction: tonic, 5.9 ± 2.5%; intermittent, 10.7 ± 2.9%. Discharge rate for the tonic units decreased progressively (13.9 ± 2.7 to 11.7 ± 2.6 pulses s−1; P= 0.04) during the 99 ± 111 s contraction. Train rate, train duration and average discharge rate for the intermittent motor units did not change across 211 ± 153 s of intermittent discharge. The initial discharge rate at recruitment during the sustained contraction was lower for the intermittent motor units (11.0 ± 3.3 pulses s−1) than the tonic motor units (13.7 ± 3.3 pulses s−1; P= 0.005), and the coefficient of variation for interspike interval was higher for the intermittent motor units (34.6 ± 12.3%) than the tonic motor units (21.2 ± 9.4%) at recruitment (P= 0.001) and remained elevated for discharge duration (34.6 ± 9.2%versus 19.1 ± 11.7%, P < 0.001). In an additional experiment, 12 motor units were recorded at two different target forces below recruitment threshold (5.7 ± 1.9% and 10.5 ± 2.4%). Each motor unit exhibited the two discharge patterns (tonic and intermittent) as observed for the 53 motor units. The results suggest that newly recruited motor units with recruitment thresholds closer to the target force experienced less synaptic noise at the time of recruitment that resulted in them discharging action potentials at more regular and greater rates than motor units with recruitment thresholds further from the target force.
D2‐like dopamine receptor‐mediated modulation of activity‐dependent plasticity at GABAergic synapses in the subthalamic nucleus
Authors: Baufreton Jérôme , Bevan Mark D.
Published: February 2008

Reciprocally connected glutamatergic subthalamic nucleus (STN) and GABAergic external globus pallidus (GP) neurons normally exhibit weakly correlated, irregular activity but following the depletion of dopamine in Parkinson's disease they express more highly correlated, rhythmic bursting activity. Patch clamp recording was used to test the hypothesis that dopaminergic modulation reduces the capability of GABAergic inputs to pattern ‘pathological’ activity in STN neurons. Electrically evoked GABAA receptor‐mediated IPSCs exhibited activity‐dependent plasticity in STN neurons, i.e. IPSCs evoked at frequencies between 1 and 50 Hz exhibited depression that increased with the frequency of activity. Dopamine, the D2‐like dopamine receptor agonist quinpirole and external media containing a low [Ca2+] reduced both the magnitude of IPSCs evoked at 1–50 Hz and synaptic depression at 10–50 Hz. Dopamine/quinpirole also reduced the frequency but not the amplitude of miniature IPSCs recorded in the presence of tetrodotoxin. D1‐like and D4 agonists were ineffective and D2/3 but not D4 receptor antagonists reversed the effects of dopamine or quinpirole. Together these data suggest that presynaptic D2/3 dopamine receptors modulate the short‐term dynamics of GABAergic transmission in the STN by lowering the initial probability of transmitter release. Simulated GABAA receptor‐mediated synaptic conductances representative of control or modulated transmission were then generated in STN neurons using the dynamic clamp technique. Dopamine‐modulated transmission was less effective at resetting autonomous activity or generating rebound burst firing than control transmission. The data therefore support the conclusion that dopamine acting at presynaptic D2‐like receptors reduces the propensity for GABAergic transmission to generate correlated, bursting activity in STN neurons.
Selective Blockade of MicroRNA Processing by Lin28
Authors: Viswanathan Srinivas R. , Daley George Q. , Gregory Richard I.
Published: February 2008

MicroRNAs (miRNAs) play critical roles in development, and dysregulation of miRNA expression has been observed in human malignancies. Recent evidence suggests that the processing of several primary miRNA transcripts (pri-miRNAs) is blocked posttranscriptionally in embryonic stem cells, embryonal carcinoma cells, and primary tumors. Here we show that Lin28, a developmentally regulated RNA binding protein, selectively blocks the processing of pri-let-7 miRNAs in embryonic cells. Using in vitro and in vivo studies, we found that Lin28 is necessary and sufficient for blocking Microprocessor-mediated cleavage of pri-let-7 miRNAs. Our results identify Lin28 as a negative regulator of miRNA biogenesis and suggest that Lin28 may play a central role in blocking miRNA-mediated differentiation in stem cells and in certain cancers.
A component model of decomposition of Spartina alterniflora in a New Jersey salt marsh
Authors: Marinucci Andrew C. , Bartha R.
Published: February 2008

Spartina alterniflora decomposition was monitored in the high and low salt marsh in litter bags (2-mm mesh). The detritus formed in this process was analyzed at various times for ash-free dry weight (AFDW) (combustion at 550 °C), total carbon (wet combustion to CO2), and total nitrogen (Kjeldahl digestion). A mathematical component model predicting the change of these parameters was developed to explain these data.The first-order decay equation Xt = X0 e−kt was used to explain AFDW and carbon changes. The k values ranged from 0.004 to 0.02 per day for data from the high and low marsh, respectively, for New Jersey. Nitrogen fluxes are described by four functions. Three of these are decay functions which theoretically model (1) loss of soluble nitrogen, (2) loss of recalcitrant nitrogenous plant material, and (3) loss of microbial nitrogen. The fourth is a logistic function which describes the microbial incorportaion of nitrogen into the detritus. Nitrogen and C/N ratio values calculated with these equations simulated values obtained from field data.
Changes of Araucaria araucana seed reserves during germination and early seedling growth
Authors: Cardemil Liliana , Reinero Antonio
Published: February 2008

Changes in the starch and protein reserves of Araucaria araucana (Mol.) Koch embryo and megagametophyte tissue during the first 90 h after the start of imbibition have been measured by colorimetric and by chromatographic methods. The starch content (about 30%) of the embryo decreases rapidly until radicle protrusion–germination (40 h) and remains relatively constant (at about 9%) after that. Starch content of the megagametophyte decreases slowly throughout the 90 h. Amylase activity and soluble carbohydrate content of the embryo peak rapidly at 20 h, decline rapidly until germination, and increase slowly thereafter. Total amylase activity of the megagametophyte does not change markedly. Total soluble-protein content of the embryo decreases during the first 20 h and increases thereafter. The embryo protein bodies also disappear during the first 20 h. The hypocotyl enlarges to a bulbous shape and may serve as a secondary protected reserve.
Some factors affecting basidiospore germination of Pleurotus sapidus
Authors: McCracken Francis I.
Published: February 2008

Basidiospore germination of Pleurotus sapidus Kalchbr. on water agar increased from less than 10% to more than 75% when open culture dishes were inverted and taped onto open dishes of yeasts. Germination on water agar was also increased in a 25–75% CO2-enriched atmosphere but was very low in higher CO2 concentrations. Malt agar alone resulted in more than 80% germination. The optimum substrate pH was 6; values below pH 5 or above pH 7 adversely affected germination. Germination greater than 85% occurred at 2 °C (11 days) to 30 °C (2 days) but was 20% at 35 °C, and there was no germination at 40 °C. Germination was unaffected by light with yellow and red filters. Unfiltered light and treatments with blue and green light significantly reduced germination. Surface disinfectants, except dilute ethanol, adversely affected germination.
Seasonal dynamics of nutrients in a Carex meadow
Authors: Auclair Allan N. D.
Published: February 2008

Nutrient accumulation in aboveground biomass and mobilization of nutrients in litter were studied on a Carex meadow in southern Quebec, Canada. Seasonal changes were characterized by short periods of rapid element uptake and release. By late May the total element levels were 80% of maximum. Accumulation of N, P, and K was rapid relative to early increments in biomass. Ca, Mg, and micronutrients were taken up from the soil solution across the season and levels paralleled changes in biomass. In early summer elements were released from litter more rapidly than litter dry weight declined. Mobility of elements decreased in the order K > Mg > P > N > Ca. Overwinter, 83% of K was released, whereas Ca concentration in litter increased overwinter and through the following summer. Immobilization of Fe in litter was pronounced. Overall, > 90% of the element mass in green late-summer shoots was retained in litter overwinter.
Responses of Ulmus americana seedlings to flooding of soil
Authors: Newsome R. D. , Kozlowski T. T. , Tang Z. C.
Published: February 2008

Flooding of soil induced several physiological, morphological, and growth changes in 12- or 13-week-old Ulmus americana L. seedlings. Among the early responses to flooding was stomatal closure, without subsequent reopening, in leaves that were fully expanded by the time flooding was initiated. However, flooding did not induce stomatal closure of leaves that completed expansion during the flooding period. Flooding greatly accelerated production of ethylene by stems. Other responses to flooding included stem swelling; production of hypertrophied lenticels and abundant adventitious roots on submerged portions of the stem; reduction in leaf formation and expansion; and inhibition of dry weight increment of leaves, stems, and roots. Some of the morphological responses to flooding appeared to be associated with accelerated ethylene production. The much greater reduction in root growth over leaf growth in flooded seedlings will create leaf water deficits and predispose seedlings to drought injury after the flood waters recede.
Mitosis and the phylogeny of Taphrina
Authors: Heath I. Brent , Ashton Mary-Lou , Rethoret Karen , Heath Michèle C.
Published: February 2008

Details of mitosis are described by serial-section electron microscopy of synchronized yeast-phase cultures of five species of Taphrina. Based primarily on the morphology and behaviour of the nucleus-associated organelles (NAOs) and modes of spindle formation we conclude that three species are typical ascomycetes which have some significant differences in their mitotic systems. Each of two cultures of a fourth species, T. deformans, was apparently a mixed culture. An ascomycete type of mitosis was shared by cells of both cultures, but one culture also had cells with another ascomycete mitotic system characterized by elaborate and unique NAOs, whereas other cells of the second culture contained a basidiomycete mitotic apparatus. The fifth species contained a typical basidiomycetous mitotic system, which indicates that it is misidentified. The detailed differences among the mitotic systems of the true Taphrina species suggest that the genus as a whole is polyphyletic but undoubtedly ascomycetous. However, a previously unreported pattern of spindle formation found in three species is only otherwise known in a red alga, which may support a common ancestry for the red algae and the ascomycetes. New observations pertinent to the mechanisms of mitosis include, in various species, (a) evidence for splitting of NAOs, and their attendant spindle microtubule arrays, during prophase, (b) spindle microtubule polymerization adjacent to the nuclear envelope prior to NAO insertion into the envelope, and (c) presence of only two to four nonkinetochore microtubules during anaphase–telophase.
Seed development in Ricinus communis (castor bean). I. Descriptive morphology
Authors: Greenwood J. S. , Bewley J. D.
Published: February 2008

The morphology of developing Ricinus communis L. cv. Hale seed was studied from fertilization to quiescence, a period of approximately 60 days under the growth conditions used. Fresh and dry weights and dimensions of the whole seed, endosperm, and embryo were also determined. The development of castor bean seed has been divided into 10 stages of approximately equal duration. We have constructed a morphological timetable which allows for the consistent and repeatable selection of seeds at each of the aforementioned stages.
A survey of epicuticular waxes among genera of Triticeae. III. Synthesis and conclusion
Authors: Baum Bernard R. , Tulloch A. P.
Published: February 2008

Characteristics of ultrastructural morphology and chemical composition of epicuticular waxes on glumes of Triticeae were combined for two series of numerical taxonomic analyses. The first, incorporating within-genus variability, utilized frequencies and information radius. The information radius matrix was subjected to Jardine–Sibson Bk clustering, then transformed to Euclidean distances for distance Wagner and principal-coordinate analyses. The second series employed a table of average character values for each genus which was subjected to four ordinations: (i) principal-component analysis of the correlation matrix, (ii) principal-component analysis of the variance-covariance matrix, (iii) principal-coordinate analysis, and (iv) nonmetric multidimensional scaling. The results are compared and general inferences are drawn. Occurrence of wax filaments on the glumes was highly correlated with presence of appreciable amounts of β-diketones in wax from the whole plant. While some genera, such as Triticum and Aegilops, appeared less closely related than expected from classification based on morphology, this procedure has suggested relationships between other genera, such as Roegneria and Hordeum and Secale and Elymus. The genera Leymus, Elymus, and Aneurolepidium were also closely related to each other and more distantly to Elytrigia, Triticum, and Agropyron. A relatively close relationship was also shown between the seven genera, Crithopsis, Eremopyron, Heteranthelium, Hordelymus, Psathyrostachys, Sitanion, and Taeniatherum, which have waxes which do not contain any β-diketones.
Initial wall formation in the endosperm of wheat, Triticum aestivum: a reevaluation
Authors: Fineran B. A. , Wild D. J. C. , Ingerfeld M.
Published: February 2008

Contrary to previous studies, cytokinesis has been observed on formation of the first anticlinal walls during initial cellularization in the endosperm of wheat. Typical phragmoplasts develop between the free nuclei in the peripheral cytoplasm, and the cell plates arising from these soon fuse with the wall of the central cell. The inner free margin of the walls, however, continues to grow towards the central vacuole within an advancing front of cytoplasm. Anticlinal walls arise around nuclei approximately simultaneously in different planes; three dimensionally the nuclei, therefore, become located within open-ended compartments of cytoplasm. The compartments then undergo cell division and develop periclinal walls by normal cytokinesis. These walls delimit the first complete layer of endosperm cells centrifugally and a new layer of open compartments centripetally. The inner compartments usually continue to grow centripetally until those from the opposite side of the grain meet. During this closing phase, along the zone where the compartments fuse, a further row of periclinal walls is formed. Subsequent immediate differentiation of endosperm involves the subdivision of the first-formed large endosperm cells into smaller cells.
Comparative effects of fixation methods using tannic acid on contrast of stained and unstained sections from Spurr-embedded plant leaves
Authors: Park Pyoyun , Yamamoto Shingo , Kohmoto Keisuke , Otani Hiroshi
Published: February 2008

The comparative effects of different fixation methods using tannic acid (TA) on contrast of stained and unstained sections from Spurr-embedded apple leaves were examined. A tetrafixation method, glutaraldehyde (GA) – osmium tetroxide (OsO4) – TA – OsO4, gave the best contrast in the unstained sections while double-fixed (GA – OsO4 and GA∙TA – OsO4) specimens showed low contrast. The unstained sections from triple-fixed (GA – OsO4 – TA and GA – TA – OsO4) leaves resulted in medium contrast. Another tetrafixation method (GA – TA – OsO4 – TA) gave fairly good contrast in unstained sections. The enhancing effect of TA on contrast was still more increased by brief double stain (uranyl acetate – lead citrate) or lead citrate alone. The results showed that the former tetrafixation method was very useful for observing the fine ultrastructure of stained and unstained sections from Spurr-embedded plant tissues. In the tetrafixed leaf cells, electron-dense cellular structures were found at the peripheral area of cells. Some rough endoplasmic reticulum (ER), some Golgi bodies, vesicles beneath plasma membranes, cell walls, plasma membranes, and amorphous materials between cell walls and plasma membranes showed increased contrast in the stained and unstained tissues. The vesicles were often found to be continuous with plasma membranes. Taking into account the distribution and function of the electron-dense organelles, the ER, Golgi bodies, and vesicles may be associated with cell wall synthesis.
Changes in carbohydrate levels during ice encasement and flooding of winter cereals
Authors: McKersie B. D. , McDermott B. M. , Hunt L. A. , Poysa V.
Published: February 2008

Carbohydrate levels and production of ethanol and malic acid were followed in the acclimated crown tissue of four cereal cultivars during ice-encasement and low-temperature-flooding treatments. Tolerance to both anaerobic stresses ranked as 'Lutescens 230' wheat > 'OAC Wintri' triticale > 'Fredrick' wheat > 'Siete Cerros' wheat. All cultivars produced more ethanol during flooding than icing treatments. The winter cereal cultivars, 'Lutescens 230,' 'OAC Wintri,' and 'Fredrick,' produced significantly more ethanol than the spring wheat, 'Siete Cerros,' but consistent differences among the winter cultivars were not observed. Malic acid was not accumulated after 7 days icing or 14 days flooding. The quantity of total available carbohydrate, total ethanol-soluble carbohydrate, and reducing sugars in the crown tissue was highest in those cultivars with high icing and flooding tolerance. In addition, the most tolerant cultivar, 'Lutescens 230,' had a greater rate of carbohydrate utilization during stress treatment than the other cultivars. Nevertheless, the loss of plant viability after ice encasement of flooding was not associated with the depletion of carbohydrate reserves. Icing was a more severe stress than flooding, and differences are indicated in the utilization of carbohydrate reserves and production of ethanol during the two stresses.
Nuclear volume and number in long-term in vitro cultures of Puccinia graminis
Authors: Bushnell W. R. , Bosacker Patricia L.
Published: February 2008

Eight cultures of Puccinia graminis f. sp. tritici which had been serially subcultured in the Cereal Rust Laboratory for 2–13 years were examined for nuclear volume, number of nuclei per cell, and dimensions of hyphae. The cultures were of two types: compact with short, wide hyphal cells (ca. 10 × 22 μm); and fluffy with long, narrow cells (ca. 5 × 80 μm). The compact cultures tended to sporulate; the fluffy ones did not. By using volume of hyphal nuclei to estimate ploidy, the cultures were judged to be of three types: compact with two haploid nuclei per cell; compact with one diploid nucleus per cell; and fluffy with two diploid nuclei per cell. The compact cultures originated from American uredial isolates of races 17, 23, 38, and 56. The fluffy cultures originated only from University of Sydney uredial isolate 334, race 126Anz6,7, or as variants of compact cultures from American race 56. A uninucleate fluffy culture which had been initiated from uredial isolate 334 by Australian workers had a nuclear volume four times those of binucleate compact cultures, suggesting that the nucleus of each cell was tetraploid. A culture of P. graminis f. sp. secalis initiated at the Cereal Rust Laboratory was compact and had mostly four nuclei per cell, each presumed to be haploid. Generally, compact cultures had more characteristics in common with the parasitic form of P. graminis than fluffy cultures did.