A smoking ban in psychiatric units: threat or opportunity?

People with severe mental illness (SMI) experience some of the worst physical health and die younger than almost any section of the population. Mental health professionals have seemed strangely indifferent to this inequality, which in other areas of health would be a national scandal. In this editorial we discuss the recently introduced smoking ban in inpatient mental health service settings, which will offer mental health services an opportunity to implement creative, evidence-based strategies to help people with SMI address smoking and nicotine addiction. In doing this, we refer to National Institute for Health and Clinical Excellence (NICE) guidance. This guidance forms the basis of national smoking policies for the general population and forms a starting point for those with SMI. Such a strategy will necessarily involve close collaboration with primary care, and we specifically examine how this might be achieved.     

‘Peripheral inhibition’ of vibration-sensitive units in the leg of the fiddler crabUca pugilator

Summary The activity of single vibration-sensitive neurons in the leg nerve of the fiddler crabUca pugilator was recorded extracellularly. All units recorded from fall into two groups according to basic differences in their spectral threshold curves. The first type of neuron can be excited over a broad frequency range (ca. 2–2,000 Hz) with minimal threshold at 15–30 Hz with 0.5–1.0 cm/s² (peak). The second type of neuron, in contrast to the first one spontaneously active, is excited only in the frequency range 2–100 Hz and shows a decrease in the nerve impulse rate at vibration frequencies up to 2 kHz. The intensity necessary for complete suppression of the firing activity is 80 cm/s² at 800 Hz, the range of frequency most sensitive for inhibition.     

ExonVisualiser – application for visualization exon units in 2D and 3D protein structures

The web application oriented on identification and visualization of protein regions encoded by exons is presented. The Exon Visualiser can be used for visualisation on different levels of protein structure: at the primary (sequence) level and secondary structures level, as well as at the level of tertiary protein structure. The programme is suitable for processing data for all genes which have protein expressions deposited in the PDB database. The procedure steps implemented in the application: I) loading exons sequences and theirs coordinates from GenBank file as well as protein sequences: CDS from GenBank and aminoacid sequence from PDB II) consensus sequence creation (comparing amino acid sequences form PDB file with the CDS sequence from GenBank file) III) matching exon coordinates IV) visualisation in 2D and 3D protein structures. Presented web-tool among others provides the color-coded graphical display of protein sequences and chains in three dimensional protein structures which are correlated with the corresponding exons.

Availability

http://149.156.12.53/ExonVisualiser/     

Synchronization of stochastic Ca²(+) release units creates a rhythmic Ca²(+) clock in cardiac pacemaker cells

In sinoatrial node cells of the heart, beating rate is controlled, in part, by local Ca2(+) releases (LCRs) from the sarcoplasmic reticulum, which couple to the action potential via electrogenic Na(+)/Ca2(+) exchange. We observed persisting, roughly periodic LCRs in depolarized rabbit sinoatrial node cells (SANCs). The features of these LCRs were reproduced by a numerical model consisting of a two-dimensional array of stochastic, diffusively coupled Ca2(+) release units (CRUs) with fixed refractory period. Because previous experimental studies showed that β-adrenergic receptor stimulation increases the rate of Ca2(+) release through each CRU (dubbed I(spark)), we explored the link between LCRs and I(spark) in our model. Increasing the CRU release current I(spark) facilitated Ca2(+)-induced-Ca2(+) release and local recruitment of neighboring CRUs to fire more synchronously. This resulted in a progression in simulated LCR size (from sparks to wavelets to global waves), LCR rhythmicity, and decrease of LCR period that parallels the changes observed experimentally with β-adrenergic receptor stimulation. The transition in LCR characteristics was steeply nonlinear over a narrow range of I(spark), resembling a phase transition. We conclude that the (partial) periodicity and rate regulation of the "Calcium clock" in SANCs are emergent properties of the diffusive coupling of an ensemble of interacting stochastic CRUs. The variation in LCR period and size with I(spark) is sufficient to account for β-adrenergic regulation of SANC beating rate.     

Remote-sensing of benthic chlorophyll: should ground-truth data be expressed in units of area or mass?

During low tide, field spectrometric data (350-1050 nm) were acquired from intertidal mudflats in the upper reaches of Sydney Harbour, after which samples of sediment were taken using a small contact core. A total of 103 spectra/sediment pairs of samples were acquired. In the laboratory, amounts of chlorophyll in the contact cores were determined spectrophotometrically. The proportion of fine sediment (<63 μm), a major factor influencing bulk-density of sediment, was measured.The relationship between the remotely sensed observations and the amounts of chlorophyll was investigated by comparing chlorophyll expressed as a mass per unit area (area-normalised values) and as a mass per unit mass (content or weight-normalised values) with: (i) reflectance between 350 and 1050 nm and (ii) a ratio of reflectance at 562 and 647 nm (R562/R647). The reflectance at wavelengths >400 nm were found to be more tightly correlated with area-normalised chlorophyll (maximal correlation=−0.51 at 666 nm) than with weight-normalised chlorophyll (maximal correlation=−0.41 at 664 nm). The relationship between R562/R647 and area-normalised chlorophyll was stronger (R²=0.66) than for weight-normalised chlorophyll (R²=0.47). The residuals from the regression of weight-normalised chlorophyll on R562/R647 were strongly correlated with the mass per unit mass of sediment that was <63 μm. There was no such relationship for residuals from the regression of area-normalised chlorophyll on R562/R647. The results demonstrate conclusively that chlorophyll measured as mass per unit mass of sediment, is inappropriate for ground-truthing remotely sensed observations of chlorophyll in intertidal benthic sediments.     

Conservation genetics of Blanding’s turtle and its application in the identification of evolutionarily significant units

Blanding’s turtle is a North American freshwater turtle whose main range occurs south of the Great Lakes; disjunct populations occur east of the Appalachian Mountains from New York to Nova Scotia. The species is listed as threatened or endangered in most of its range. We employed five variable microsatellites to examine samples of 300 individuals in 12 populations. Estimates of F _ST based on pairwise comparisons of populations ranged from 0.000 to 0.465. Phylogenetic analysis of these F _ST values reveals that the Appalachian Mountains and the Hudson River appear to present major barriers to gene flow in Blanding’s turtle. The extent of fine-scale genetic structure previously reported in the Nova Scotian populations was not found in other parts of the species’ range. We recommend that populations separated by the Appalachian Mountains as well as the highly disjunct Nova Scotian populations of Blanding’s turtle be recognized as evolutionarily significant units.     

Organometallic π-tweezers incorporating pyrazine- and pyridine-based bridging units

Pyrazine- and pyridine-based π-conjugated σ-donor molecules, such as 4,4′-bipyridine, 1,2-di(4-pyridyl)ethylene, 3,5-dipyridyl-1,2,4-triazole, N,N′-bis(4-pyridylmethylidene)benzene-1,4-diamine, 2,5-di(pyridylmethylidene)cyclopentanone, 2,6-di(4-pyridylmethylidene)cyclohexanone (LL, 2a-2g) can successfully be used to span heterobimetallic π-tweezer units of the type [{[Ti](μ-σ,π-CCSiMe₃)₂}M]⁺ ([Ti] = (η⁵-C₅H₄SiMe₃)₂Ti; M = Cu, Ag). The thus accessible di-cationic species [{[Ti](μ-σ,π-CCSiMe₃)₂}MLLM{(Me₃SiCC-μ-σ,π)₂[Ti]}]²⁺ (4), which are formed via the formation of [{[Ti](μ-σ,π-CCSiMe₃)₂}MLL]⁺ (3) complexes, can be isolated in yields between 66% and 99%.However, when C₅H₄NCHCHC₆H₄CHCHNC₅H₄ (5a) and C₅H₄NCHNC₆H₄CHCHNC₅H₄ (5b), respectively, are reacted with {[Ti](μ-σ,π-CCSiMe₃)₂}AgBF₄(1c) in a 1:1 molar ratio, then the silver(I) ion is released from the organometallic π-tweezer 1c and coordination polymers [AgBF₄ · 5a]_n (6a) and [AgBF₄ · 5b]_n (6b) along with [Ti](CCSiMe₃)₂ (7) are formed in quantitative yield.     

Motor control: basic units of cortical output?

Observing movement evoked by stimulating a single cortical neuron has proven technically impossible - until now. A new study using intracellular stimulation has revealed that the basic unit of cortical output is not necessarily basic.     

Estimation of contractile parameters of successive twitches in unfused tetanic contractions of single motor units – A proof-of-concept study using ultrafast ultrasound imaging in vivo

During a voluntary contraction, motor units (MUs) fire a train of action potentials, causing summation of the twitch forces, resulting in fused or unfused tetanus. Twitches have been important in studying whole-muscle contractile properties and differentiation between MU types. However, there are still knowledge gaps concerning the voluntary force generation mechanisms. Current methods rely on the spike-triggered averaging technique, which cannot track changes in successive twitches’ properties in response to individual neural firings. This study proposes a method that estimates successive twitches contractile parameters of single MUs during low force voluntary isometric contractions in human biceps brachii. We used a previously developed ultrafast ultrasound imaging method to estimate unfused tetanic activity signals of single MUs. A twitch decomposition model was used to decompose unfused tetanic activity signals into individual twitches. This study found that the contractile parameters varied within and across MUs. There was an association between the inter-spike interval and the contraction time (r = 0.49, p < 0.001) and the half-relaxation time (r = 0.58, p < 0.001), respectively. The method shows the proof-of-concept to study MU contractile properties of individual twitches in vivo, which can provide further insights into the force generation mechanisms of voluntary contractions and response to individual neural discharges.     

Are isolated maternity units run by general practitioners dangerous?

A retrospective survey was carried out of women admitted in labour to an isolated maternity unit run by general practitioners in Penrith. In the five years 1980-4, 1267 women began labour in Penrith, of whom 1153 (91%) never required help from a consultant unit. Ninety required transfer during labour. Ten mothers and four neonates required transfer during the early puerperium, all to one receiving unit in Carlisle. There were six perinatal deaths during the five years; five occurred in babies delivered after transfer. The perinatal mortality was 4.7/1000. The low mortality, the low level of intervention, and the preference of women all support the retention of isolated units.     

Accelerating the Gillespie τ-Leaping Method using graphics processing units

The Gillespie τ-Leaping Method is an approximate algorithm that is faster than the exact Direct Method (DM) due to the progression of the simulation with larger time steps. However, the procedure to compute the time leap τ is quite expensive. In this paper, we explore the acceleration of the τ-Leaping Method using Graphics Processing Unit (GPUs) for ultra-large networks (>0.5e(6) reaction channels). We have developed data structures and algorithms that take advantage of the unique hardware architecture and available libraries. Our results show that we obtain a performance gain of over 60x when compared with the best conventional implementations.     

Modeling investigation of learning a fast elbow flexion in the horizontal plane—prediction of muscle forces and motor units action

Experimental investigation of practicing a dynamic, goal-directed movement reveals significant changes in kinematics. Modeling can provide insight into the alterations in muscle activity, associated with the kinematic adaptations, and reveal the potential motor unit (MU) firing patterns that underlie those changes. In this paper, a previously developed muscle model and software (Raikova and Aladjov, Journal of Biomechanics, 35, 2002) have been used to investigate changes in MU control, while practicing fast elbow flexion to a target in the horizontal plane. The first trial (before practice) and the last trial (after extensive practice) of two subjects have been simulated. The inputs for the simulation were the calculated external moments at the elbow joint. The external moments were countered by the action of three flexor muscles and two extensor ones. The muscles have been modeled as a mixture of MUs of different types. The software has chosen the MU firing times necessary to accomplish the movement. The muscle forces and MUs firing statistics were then calculated. Three hypotheses were tested and confirmed: (1) peak muscle forces and antagonist co-contraction increase during training; (2) there is an increase in the firing frequency and the synchronization between MUs; and (3) the recruitment of fast-twitch MUs dominates the action.     

Are geriatric units needed for elderly patients with hip fractures?

To assess the need for a multidisciplinary geriatric unit in the treatment of elderly patients with hip fractures, we reviewed the charts of all patients aged 60 years or older who were treated for hip fractures in five hospitals in Hamilton, Ont., between August 1982 and September 1983. We hypothesized that discharge to a different location from that before admission would indicate reduced functional status and classified the reasons for a change in residence as poor patient motivation, need for rehabilitation, compromised ambulation, postoperative complications and inevitable deterioration. We believed that geriatric care would be most beneficial to those in the first three groups. Of the 327 patients with hip fractures 40 (12%) died before discharge. Of the 287 surviving patients 149 (52%) had been discharged by 4 weeks, and only 29 (10%) remained in hospital by 12 weeks. Of the 287, 44 (15%) were discharged to a different location from that before admission: in 75% the cause appeared to be inevitable deterioration (57%) or postoperative complications (18%). The remaining 25% needed rehabilitation and were all sent to appropriate facilities. None of the patients with ambulation problems or poor motivation required an increased level of care. We could not show a need for geriatric care in our population; possible explanations are discussed.     

IgG from patients with liver diseases inhibit mitochondrial respiration in permeabilized oxidative muscle cells: Impaired function of intracellular energetic units?

The effect of IgG purified from the sera of healthy persons and patients with primary biliary cirrhosis (PBC) and chronic hepatitis (CH) on ADP dependent respiration (oxidative phosphorylation) in skinned muscle fibers from rat oxidative muscles (heart and M. soleus) and glycolytic skeletal muscle (M. gastrocnemius) was studied. The results show that IgG from three different sources inhibited the rate of respiration by 13, 44 and 42%, respectively, these effects being equally expressed in both types of oxidative muscles, whereas no inhibition was observed in glycolytic muscle. The following washout of unbound IgG did not abolish the inhibition of respiration suggesting that the specific interaction of IgG with antigens had taken place. Laser confocal analysis revealed binding of IgG predominantly to the sarcomeric structures such as Z-disk and M-lines in the cardiomyocytes. The staining of IgG within Z-disks and intermitochondrial space coincided throughout the muscle cells so that transversally serial spaces, each containing mitochondria and adjacent sarcomere, became clearly visible. When the IgG from a CH patient was incubated with the skinned myocardial fibers of the desmin knockout mice, its binding to Z-disks and the sarcomeric area was found to be similar to that in normal cardiac muscle. However, the transversal staining pattern was disintegrated, because of the slippage of the myofibrils in relation to each other and accumulation of mitochondria between them. These observations support the recent hypothesis that in oxidative muscles the mitochondria and adjacent sarcomeres form complexes, termed as the intracellular energetic units, ICEUs. Moreover, they indicate that human autoantibodies can be useful tools for localizing the proteins responsible for formation of ICEUs and modulation of their function. Thus, it appears that the proteins associated with the Z-disks and M-lines may participate in formation of ICEUs and that binding of IgG to these proteins decreases the access of exogenous adenine nucleotides to mitochondria, which manifests as decreased rate of ADP-dependent respiration.