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In road traffic collisions, pedestrian injuries and fatalities account for approximately 11% and 20% of casualties in the USA and the EU, respectively. In many less motorised countries, the majority of victims are pedestrians. The significant influences of vehicle speed, pedestrian speed and pedestrian gait on pedestrian post-impact kinematics have been qualitatively noted in the literature, but there has been no quantitative approach to this problem. In this paper, the MADYMO MultiBody (MB) pedestrian model is used to analyse the influences of vehicle speed, pedestrian speed and pedestrian gait on the transverse translation of the pedestrian's head, head rotation about the vertical head axis and head impact velocity. Transverse translation has implications for injury severity because of variations in local vehicle stiffness. Head rotation is related to pedestrian stance at impact, which is known to affect the kinematics of a collision. Increased head impact velocity results in greater head injury severity. The results show that transverse translation of the head relative to the primary contact location of the pedestrian on the vehicle decreases with increasing vehicle speed and increases linearly with increasing pedestrian speed. Head rotation decreases with increasing vehicle speed and increases linearly with increasing pedestrian speed, but these variations are small. The range of head rotation values decreases with increasing vehicle speed. Head impact velocity increases linearly with vehicle speed and is largely independent of pedestrian speed. Transverse translation, head rotation and head impact velocity all vary cyclically with gait in clearly definable patterns., (Copyright © 2011 Elsevier Ltd. All rights reserved.)

We performed a retrospective review of all patients admitted to two large University Hospitals in the United Kingdom over a 24-month period from January 2008 to January 2010 to identify the incidence of atypical subtrochanteric and femoral shaft fractures and their relationship to bisphosphonate treatment. Of the 3515 patients with a fracture of the proximal femur, 156 fractures were in the subtrochanteric region. There were 251 femoral shaft fractures. The atypical fracture pattern was seen in 27 patients (7%) with 29 femoral shaft or subtrochanteric fractures. A total of 22 patients with 24 atypical fractures were receiving bisphosphonate treatment at the time of fracture. Prodromal pain was present in nine patients (11 fractures); 11 (50%) of the patients on bisphosphonates suffered 12 spontaneous fractures, and healing of these fractures was delayed in a number of patients. This large dual-centre review has established the incidence of atypical femoral fractures at 7% of the study population, 81% of whom had been on bisphosphonate treatment for a mean of 4.6 years (0.04 to 12.1). This study does not advocate any change in the use of bisphosphonates to prevent fragility fractures but attempts to raise awareness of this possible problem so symptomatic patients will be appropriately investigated. However, more work is required to identify the true extent of this new and possibly increasing problem.

The 2001 Report of the National Confidential Enquiry into Perioperative Deaths recommended that an echocardiogram should be performed on patients with aortic stenosis prior to anaesthesia. In this study we present the patient details, management and outcome of the 272 hip fracture patients with a previously undiagnosed murmur and echocardiographically proven aortic stenosis admitted from 2001-2005 in our hospital. The patients with aortic stenosis were significantly older, and had significantly lower Abbreviated Mental Test Scores, than the control group of 3698 hip fracture patients without aortic stenosis. There were significant trends toward general anaesthesia over spinal anaesthesia, and use of invasive monitoring of blood pressure, as the severity of the aortic stenosis increased. There were no significant trends towards higher 30-day or 1-year mortality rates as the severity of the aortic stenosis increased. Resources for rapid pre-operative echocardiograms should be made available for hip fracture patients as the results have significant implications for their subsequent anaesthetic management.

Objective: To study the outcome following treatment for proximal femoral fracture in elderly people., Methods: All consecutive males and females admitted to the acute fracture service at the Royal Victoria Hospital and the Belfast City Hospital for the 3 years from 1999 to 2001 were studied. The data was collected by trained research nurses. Variables gathered included age, sex, marital status, mental state, pre-injury Barthel score and the American Society of Anaesthesiology (ASA) physical status grading. The information was gathered on admission to hospital and at four, six and 12 months after the injury., Results: The total number of patients studied between January 1999 to December 2001 was 2834 of whom 77% were female and 23% were male. The mean (median) length of stay in the acute fracture service was 10.7 (9 days). The mean (median) length of stay in the rehabilitation ward was 35.3 (24 days). The 30-day mortality was 6.9%, the four-month mortality 15.6 % and one year mortality 22.3 %. Of those subjects living at home at the time of fracture 68% remained at home at one year. Factors predicting successful return home were higher mental test score, younger age, female sex, higher Barthel score, better pre-injury mobility and better ASA score. Of those able to walk independently outdoors before injury 40% regained this ability by 12 months. Factors predicting return of pre-injury mobility were poorer pre-injury mobility, younger age, higher mental test score, better ASA category, higher Barthel score, and previous residence at home. The proportion admitted from their own home and discharged by 56 days was 56%., Conclusion: The standardised measurement of outcome in hip fracture subjects enables comparison between units and facilitates improvement in standards of care available to the increasing number of elderly patients presenting with proximal femoral fracture.

(1) Voltage-gated K+ channels are inhibited by a variety of clinical and experimental drugs. (2) Complex changes in channel gating suggest mechanisms in which drug affinity depends on channel state. (3) Here, we use the effects of external TEA+, two local anaesthetics (lidocaine and bupivacaine), and phenol on rat brain Kv1.1 K+ channels expressed in Xenopus oocytes to illustrate three mechanisms. (4) The open state has the highest affinity in the local anaesthetic model but the lowest in the phenol model, and while local anaesthetics simply block the open channel, phenol can produce a conducting but destabilized open state. (5) All states have equal affinity for external TEA+.

1. Whole-cell and single-channel Na+ currents were recorded from small (ca. 20 micron diameter) cells isolated from adult rat dorsal root ganglia (DRG). Currents were classified by their sensitivity to 0.3 microM tetrodotoxin (TTX), electrophysiological properties and single-channel amplitude. Cells were classified according to the types of current recorded from them. 2. Type A cells expressed essentially pure TTX-sensitive (TTX-S) currents. Availability experiments with prepulse durations between 50 ms and 1 s gave a half-available voltage (Vh) of around -65 mV but the availability curves often had a complex shape, consistent with multiple inactivation processes. Measured inactivation time constants ranged from less than 1 ms to over 100 s, depending on the protocol used. 3. Cell types B and C each had, in addition to TTX-S currents, substantial and different TTX-resistant (TTX-R) currents that we have designated TTX-R1 and TTX-R2, respectively. TTX-R1 currents had a 1 s Vh of -29 mV, showed little 1 Hz use dependence at -67 mV and recovered from the inactivation induced by a 60 ms depolarizing pulse with time constants of 1.6 ms (91 %) and 908 ms. They also exhibited slow inactivation processes with component time constants around 10 and 100 s. TTX-R2 currents activated and inactivated at more negative potentials (1 s Vh = -46 mV), showed substantial 1 Hz use dependence and had inactivation (60 ms pulse) recovery time constants at -67 mV of 3.3 ms (58 %) and 902 ms. 4. Type D cells had little or no current in 0.3 microM TTX at a holding potential of -67 mV. Current amplitude increased on changing the holding potential to -107 mV. Type D cell currents had more hyperpolarized availability and I-V curves than even TTX-R2 currents and suggest the existence of TTX-R3 channels. 5. In outside-out patches with 250 mM external NaCl, the single-channel conductance (gamma) of TTX-S channels was 19.5 pS and the potential for half-maximal activation (Va) was -45 mV. One population of TTX-R channels had a gamma of 9.2 pS and a Va of -27 mV. A second population had a gamma of 16.5 pS and a more negative Va of -42 mV. The latter population may underlie the type D cell current. 6. Small DRG cells express multiple Na+ currents with varied time constants and voltage dependences of activation and inactivation. Nociceptive cells still fire when chronically depolarized by an increased external K+ concentration. TTX-R1 and TTX-R2 Na+ channels may support that firing, while the range of inactivation time constants described here would increase the repertoire of DRG cell burst firing behaviour generally.

We have previously shown that although n-octyl sulphate (OS-) and n-dodecyl sulphate (DDS-) anions had similar effects on the kinetics and activation voltage dependence of RCK1 (Kv1.1), RCK4 (Kv1.4) and Shaker B channels expressed in Xenopus oocytes, both compounds produced a large decrease in the maximum conductance of RCK4 channels while significantly increasing the conductance of RCK1 and Shaker B. We suggested that this channel-specific inhibition might depend on the nature of the amino-acid residue corresponding to position 533 in RCK4. We now present data on the effects of n-alkyl sulphates on an RCK4 mutant in which the wild-type lysine at position 533 was changed to the corresponding tyrosine residue in RCK1. At a concentration of 15 microM, DDS- caused a 48% reduction in the wild-type current at 50 mV but a 32% increase in the mutant current. n-Hexyl sulphate and OS- had similar differential effects. The activation and inactivation kinetics of the mutant current were still accelerated by n-alkyl sulphates and 15 microM DDS- moved the conductance/voltage curves of both wild-type and mutant channels some 24 mV in the hyperpolarizing direction. The K533Y mutation thus had a selective effect on current inhibition by n-alkyl sulphates.

Besides the fast tetrodotoxin-sensitive Na+ current, small dorsal root ganglion neurones of rats also possess a slower tetrodotoxin-resistant Na+ current. The blocking effect of commonly used local anaesthetics upon the tetrodotoxin-resistant Na+ current was investigated in the present paper. Dorsal root ganglia were dissected from adult rats and cells were enzymatically isolated. The whole-cell patch clamp technique was then used to measure inward Na+ currents of small dorsal root ganglion neurones. Externally applied local anaesthetics reversibly blocked the tetrodotoxin-resistant Na+ current in a dose-dependent manner. Half-maximal blocking concentrations for tonic block were: lignocaine, 326 microM; prilocaine, 253 microM; mepivacaine, 166 microM; etidocaine, 196 microM bupivacaine, 57 microM procaine, 518 microM benzocaine, 489 microM; tetracaine, 21 microM; and dibucaine, 23 microM. Blocking of the current by lignocaine was independent of temperature. The quaternary lignocaine derivative OX-314 did not have any effect upon the tetrodotoxin-resistant Na+ current when applied externally. High concentrations of tetrodotoxin also blocked the tetrodotoxin-resistant Na+ current with a half-maximal blocking concentration of 115 microM. The block by high tetrodotoxin concentrations did not compete with the lignocaine block, suggesting that there were two independent blocking mechanisms for the two substances. The tetrodotoxin-resistant Na+ currents also showed a marked sensitivity to phasic (use-dependent) block by local anaesthetics.

This article provides a simple introduction to the simulation of voltage-dependent ion conductances in both macroscopic and single-channel modes. Only Markovian (time-independent) systems are considered. The programmes listed are written in Microsoft QBasic or QuickBASIC but versions in other languages are available. The Hodgkin-Huxley Na+ current is used as a starting system for which an explicit macroscopic solution may be obtained and compared with the results of numerical simulations employing 4th order Runge-Kutta integration. Non-Hodgkin-Huxley behaviour such as voltage-independent inactivation and double exponential current decay are discussed and simulated. A stochastic programme is used to simulate single channel behaviour. The problems and methodologies involved in fitting experimental data using complex kinetic schemes are briefly discussed, as are alternative sources of simulation software.

n-Alkyl sulphate anions have been shown to reversibly affect the functioning of voltage-gated ion channels in a variety of preparations. They are suggested to exert their effects by increasing the magnitude of the negative surface potential at the external face of the membrane. Here we report the effects of n-octyl sulphate (OS-) and n-dodecyl sulphate (DDS-) on RCK1 (Kv1.1), RCK4 (Kv1.4) and Shaker B potassium channels exogenously expressed in Xenopus oocytes. Both OS- and DDS- produced a hyperpolarising shift in the activation voltage dependence of all three channels, consistent with an increased negative external surface potential. Similar kinetic changes were also observed, the kinetics of both activation and inactivation being accelerated in the presence of OS- and DDS-. However, we also found that while 10 mM OS- and 50 microM DDS- significantly increased the maximum conductance of RCK1 and Shaker B channels, 5 mM OS- and 15 microM DDS- produced a large decrease in RCK4 conductance; the possible involvement of RCK4 residue K533 in this effect is discussed. Our data indicate that n-alkyl sulphate anions can perturb ion channel function in a variety of ways and that their effects are complex and channel specific.

We determined the effects of carbamazepine and phenytoin, anticonvulsant drugs used to treat neuropathic pain, on the heterogeneous population of Na+ channels in patch-clamped small cells from adult rat dorsal root ganglia. Both fast tetrodotoxin-sensitive (TTX-S) and slow TTX-resistant (TTX-R) currents were inhibited by 10-100 microM drug. TTX-R currents were divided into two classes. Control type I currents had a very depolarized voltage for 50% availability (Vh) of ca. -29 mV and 17% reduction in current by the 20th pulse at 1 Hz. Control type II currents had a Vh closer to -46 mV and 49% reduction in current at 1 Hz. At 0.1 Hz, which gave relatively little loss of control current, 100 microM drug caused 53 +/- 4% (n = 5) block of type I current and 88 +/- 2% inhibition of type II current (n = 4). Strong 1 s hyperpolarizing prepulses relieved most of the fast channel block but had much less effect on blocked TTX-R channels.

Neuropathic pain may result from sustained firing of sensory neurones. The questions are what initiates and what stops that firing? Spontaneous firing of a modified Hodgkin-Huxley model axon is induced here by: (1) a depolarizing shift in the K+ channel activation parameter; and (2) a positive change in the K+ equilibrium potential. The duration and pattern of spontaneous discharge is seen to be critically dependent on the level and kinetics of Na+ channel slow inactivation. Slow inactivation of voltage-gated ion channels could be major factors in the induction and treatment of neuropathic pain.

Phenol has various medical applications but can cause convulsions and cardiac arrhythmia suggestive of K+ channel block. We examined phenol inhibition of the delayed-rectifier RCK1 (Kv1.1) K+ channel cloned from rat brain and expressed in Xenopus laevis oocytes. Phenol (2.5 mM) caused a 43 +/- 5 mV depolarizing shift in the RCK1 half-activation voltage (Vg) but only a 10 +/- 3% decrease in the peak conductance at 80 mV. The 10-90% rise time was slightly increased, but this was not simply the result of the activation shift. By contrast, deactivation kinetics at -40 mV were greatly accelerated. The importance of the phenolic hydroxyl group was assessed by comparing the effects of p-cresol (a phenol) and its structural isomer benzyl alcohol (an aryl alcohol). p-Cresol (1.5 mM) produced a 53 +/- 2 mV depolarizing shift in Vg, but benzyl alcohol was much less effective--20 mM caused a depolarizing shift of only 23 +/- 1 mV. Both isomers also accelerated channel deactivation. Phenol and p-cresol are better hydrogen bond donors than acceptors, whereas benzyl alcohol is a better acceptor than donor. A hydrogen bond between the phenolic hydroxyl and a presently unknown acceptor group may therefore underlie some aspects of K+ channel inhibition. Depolarizing shifts in Vg and accelerated tail kinetics are consistent with 1) preferential phenol binding to resting channels, causing the shift in Vg, and 2) a conducting phenol-bound open state with faster deactivation kinetics than the unbound open state.

Monophasic compound action potentials were recorded from Rana sciatic nerves. Three distinct peaks were observed and designated A alpha, A delta and C. All peaks were abolished by replacement of the external medium with Na(+)-free solution. However, the C peak alone was unaffected by external application of 1 microM tetrodotoxin (TTX), both A peaks were completely suppressed. The C peak was also the most resistant to chronic depolarization caused by increased external K+. K+ (17.6 mM) solution reduced peak areas to 5 +/- 4, 27 +/- 11 and 63 +/- 14% of control for A alpha, A delta and C components. The C peak was therefore Na(+)-dependent, TTX-resistant and K(+)-depolarization resistant. These attributes are similar to those described for somatal TTX-resistant Na+ channels in other species. But, application of 1 microM TTX to a K(+)-depolarized nerve caused a further reduction in C peak area, suggestive of a voltage-dependent block by TTX similar to that reported for cardiac muscle Na+ channels.

Serum and synovial tissue from 26 patients with rheumatoid arthritis (RA) (according to the diagnostic criteria of the American Rheumatism Association) and 26 patients with osteoarthritis (OA) were examined. Among the RA group, the female to male ratio was 4.2:1, and the age range was 44-82 yr with a mean of 64.0 yr; joints from which synovium was sampled were hip (n = 12), knee (n = 9), ankle (n = 3) and shoulder (n = 2). The duration of rheumatoid disease ranged from 6 to 24 yr with a mean of 13.9 yr. Among the OA group, the female to male ratio was 2.25:1, and the age range was 51-88 yr with a mean of 68.2 yr; joints from which synovium was sampled were hip (n = 18) and knee (n = 8). Twenty-one patients from the RA group and 20 patients from the OA group had evidence of previous parvovirus B19 infection (serum anti-B19 IgG), and all patients from both groups were serum anti-B19 IgM negative. Synovial sections from all 52 patients were stained with mouse monoclonal antibodies, 3H8 (to B19 capsid proteins) and alpha-P (to blood group P antigen). All tissue sections examined were found to be negative for both B19 capsid proteins and blood group P antigen. Using a nested polymerase chain reaction (PCR) assay, all patients were negative for serum B19 DNA. However, B19 DNA was demonstrated in the synovium of 10 of 26 RA patients and 9 of 26 OA patients; uncorrected chi 2 value = 0.08; degrees of freedom = 1; P = 0.77. All 19 patients testing positive for synovial B19 DNA had evidence of prior exposure to B19 infection (serum anti-B19 IgG). In conclusion, although there is published evidence of chronic rheumatoid-like arthropathy following acute parvovirus B19 infection, our findings do not support the involvement of B19 in the aetiopathogenesis of RA.

The effects of low and clinically relevant concentrations of inhalation anaesthetics and related compounds on the firing behaviour of nerve axons from a number of species are described. The observation of substantial, if sometimes transient, changes in excitability is contrasted with the view that axonal ion channels are insensitive to many general anaesthetics. Taking the squid giant axon as a well-studied example, we show that a full understanding of these effects can only be achieved through a detailed investigation of the actions of a range of compounds on a number of ion channels. Small alterations in the properties of individual channel types can in combination result in major changes in the behaviour of a multi-channel system such as an axon. Finally, as an example of the spectrum of activity of structurally related compounds, we compare the effects of inhalation anaesthetics with those of volatile convulsants.

A case is described of compartment syndrome of the lower leg after closed intramedullary nailing of the tibia in which the diagnosis was delayed because an epidural analgesia technique masked the pain. The syndrome was treated by open four-compartment fasciotomy.

Many effects of short-chain phospholipids and n-alkanes on the squid axon sodium current (INa) are consistent with mechanisms involving changes in membrane thickness. Here, we suggest that the actions of short-chain phospholipids on an A-type potassium current (IA) in two-microelectrode voltage clamped Helix D1 and F77 neurons are incompatible with such simple mechanisms. Diheptanoyl phosphatidylcholine (diC7PC, 0.2 and 0.3 mM) caused substantial (58 and 79%), and in some cases partially reversible, increases in IA amplitude. These were correlated with hyperpolarizing shifts of up to -7 mV in the voltage dependence of current activation. The voltage dependence of steady-state inactivation was also moved in the hyperpolarizing direction. These effects are the opposite of those described for squid INa. 0.5 Saturated n-pentane and saturated n-hexane caused significant (-3 and -6 mV) hyperpolarizing shifts in the voltage dependence of IA inactivation, qualitatively consistent with their effects on squid INa, while the voltage dependence of activation was moved slightly to the left or unchanged. Hydrocarbons had variable effects on peak current amplitude, although saturated n-pentane produced a clear suppression. DiC7PC caused a 25% increase in the time constant of macroscopic IA inactivation (tau b) but 0.5 saturated n-pentane and saturated n-hexane reduced tau b by 40%. The effects of these agents on current-clamped cells were broadly consistent with their opposing actions on tau b--phospholipids tended to reduce excitability and n-alkanes tended to increase it. Possible mechanisms of IA perturbation are discussed.

Thirty consecutive cases requiring total knee replacement (TKR) were treated using the Richards Tricon Total Knee System with ASAP (All Six, All Precise) instrumentation (Richards Medical Company, Memphis, TN, USA). Preoperative and postoperative overall coronal alignment were measured using long-leg anteroposterior X-rays. The femoral and tibial bone cuts in this plane were assessed using intraoperative films. The aim was to achieve a postoperative coronal tibio-femoral alignment of 7 degrees valgus. The mean preoperative alignment was 1 degree valgus (SD = +/- 13.5 degrees). A mean postoperative alignment of 8 degrees valgus was obtained (SD = +/- 5.6 degrees). The results obtained in this series suggest that the ASAP system with careful use simplifies the technique of total knee replacement while maintaining accuracy.

1. The whole-cell patch-clamp technique was used to investigate the characteristics of two types of sodium current (INa) recorded at room temperature from small diameter (13-25 microns) dorsal root ganglion (DRG) cells, isolated from adult rats and maintained overnight in culture. 2. Sodium currents were isolated pharmacologically. Internal Cs+ and external tetraethylammonium (TEA) ions were used to suppress potassium currents. A combination of internal EGTA, internal F-, a low (10 microM) concentration of external Ca2+ and a relatively high (5 mM) concentration of internal and external Mg2+ was used to block calcium channels. The remaining voltage-dependent currents reversed direction at the calculated sodium equilibrium potential. Both the reversal potential and magnitude of the currents exhibited the expected dependence on the external sodium concentration. 3. INa subtypes were characterized initially in terms of their sensitivity to tetrodotoxin (TTX). TTX-sensitive (TTXs) currents were at least 97% suppressed by 0.1 microM TTX. TTX-resistant (TTXr) INa were recorded in the presence of 0.3 microM TTX and appeared to be reduced in amplitude by less than 50% in 75 microM TTX (n = 1). 4. As in earlier studies, the peak of the current-voltage relationship, the mid-point of the normalized conductance curve and the potential (Vh) at which the steady-state inactivation parameter (h infinity) was 0.5 were found to be significantly more depolarized for the TTXr INa (by ca 10, 14 and 37 mV respectively). There was little difference in the slope at the mid-point of the normalized conductance curves (the mean slope factors were 5.1 mV for the TTXs INa and 4.9 mV for the TTXr current) but the h infinity curves for TTXr currents were significantly steeper than those for TTXs currents (mean slope factors of 3.8 and 11.5 mV respectively). Both the time to peak and the decay time constant of the peak current recorded from a holding potential of -67 mV were more than a factor of three slower for the TTXr INa than for the TTXs current. 5. However, in direct contrast to the difference in activation and decay kinetics, 'slow' TTXr INa recovered from inactivation at -67mV, or reprimed, more than a factor of ten faster than 'fast' TTXs INa. 6. The differences apparent in both the repriming kinetics of TTXs and TTXr INa at -67 mV and the kinetics of the decay phase of the peak INa are shown to be explicable largely in terms of the voltage dependence of their respective inactivation systems.(ABSTRACT TRUNCATED AT 400 WORDS)

1. The effects of clinical inhalation anaesthetics, such as halothane and methoxyflurane, and "model" anaesthetics, such as hydrocarbons and n-alkanols, on neuronal sodium and potassium channels are reviewed. 2. Lipid-based mechanisms for the actions of anaesthetics on the gating parameters of squid axon sodium and delayed rectifier potassium currents are considered in conjunction with evidence of more specific effects in other preparations, notably a fast inactivating potassium current in Helix neurones and a voltage-gated sodium current in rat dorsal root ganglion neurones. 3. The proconvulsant actions of some inhalation anaesthetics are discussed in relation to the induction of spontaneous firing of action potentials in the squid giant axon.

1. A two-microelectrode voltage clamp was used to determine the effects of n-butanol, n-hexanol, n-octanol, n-decanol and methyl hexanoate on a transient potassium (IA) current in identified Helix aspersa neurones. Experiments were carried out at a temperature of 10-12 degrees C. 2. Each n-alkanol reversibly reduced the amplitude of the IA current. Logarithmic dose-response curves for the current reduction by each homologue were sigmoidal and had slope factors of around four. The concentrations required to reduce the peak (with time) current at -30 mV by 50% (ED50 +/- fitted standard error) were: 57 +/- 5 mM (n-butanol); 2.0 +/- 0.1 mM (n-hexanol); 0.28 +/- 0.02 mM (n-octanol) and 0.016 +/- 0.001 mM (n-decanol). Methyl hexanoate also reduced the current amplitude, with an ED50 of 1-2 mM. The Helix IA current thus showed a similar sensitivity to n-alkanols to that of squid and rat sodium currents but was rather more sensitive than the squid delayed rectifier potassium current. 3. The n-alkanol ED50 concentrations were used to calculate a standard free energy per methylene group for adsorption to a site of action in the cell of -3.1 +/- 0.2 kJ/mol. This suggested a hydrophobic site or sites of action. The regularity of the change in free energy with chain length was maintained up to, and including, n-decanol. This implied that the site(s) could accommodate a ten-carbon chain as readily as an eight-carbon chain. 4. The voltage dependencies of IA current activation and steady-state inactivation were not consistently altered by treatment with n-alkanols at concentrations around or above their current suppression ED50 concentrations. 5. The kinetics of current activation and inactivation were affected, particularly by lower chain length compounds. At 60 mM n-butanol reduced the time constant for development of inactivation of open channels (tau b) by 56%, while 0.016 mM n-decanol produced only a 13% reduction. n-Butanol (60 mM) also caused a substantial (76%) reduction in the time constant for development of inactivation in channels which were presumed to be closed. The effects of n-alkanols on the current time-to-peak (tc) were complex, showing both increases and decreases, but these actions also declined with chain length. Methyl hexanoate (1 mM) reduced tau b by around 30% and tc by around 20%. 6. n-Alkanols have now been shown to inhibit a number of voltage-gated ion conductances.(ABSTRACT TRUNCATED AT 400 WORDS)

1. The whole-cell patch-clamp technique was used to determine the actions of n-octyl sulphate (OS-) anions and n-octyl trimethylammonium (OTMA+) cations on sodium current steady-state inactivation and peak amplitude in cells isolated from dorsal root ganglia of neonatal rats and maintained in short-term tissue culture. This paper concentrates on the effects of external addition but the actions of internal OS- and OTMA+ are briefly considered. 2. The main action of external OS- was to cause a hyperpolarizing shift in the voltage dependence of the steady-state inactivation parameter, h infinity. At 1-6 mM OS- caused a shift in the mid-point of the h infinity curve of around -30 mV. The shape of the h infinity curve was altered in a concentration-dependent manner. Internal OS- had no discernible effect on the shape or position of the h infinity curve. 3. External OS- produced a relatively small (less than 25%) reduction in the maximum current achieved following pre-pulses sufficiently negative to remove resting steady-state inactivation. 4. By contrast, external OTMA+ had little effect on the voltage dependence of h infinity and produced a small, but significant, increase in the maximum sodium current. 2 mM-external OTMA+ moved the mid-point of the h infinity curve (Vh) 5 mV in the depolarizing direction (relative to the mean of control and reversal curves) and increased the maximum current by 13%. One millimolar internal OTMA+ induced a frequency-dependent current block. 5. Raising the external calcium concentration from 2 to 20 mM (in the presence of 2 mM-magnesium and 5 mM-cobalt) caused an 18 mV depolarizing shift in Vh, consistent with a reduction in the negativity of an external surface charge. The maximum current was reduced by 22%. 6. One millimolar OS- reduced the surface potential of egg phosphatidylcholine (EPC) monolayers (at an air-0.5 M-NaCl interface) by 35 mV but 1 or 2 mM-OTMA+ produced only a 2-3 mV increase. The quantitative agreement between the effects of OS-, on Vh in the rat and on monolayer surface potential, decreased with increasing concentration.(ABSTRACT TRUNCATED AT 400 WORDS)

We have studied a normal adult caucasian population (462 females, 264 males age range 20-84) using dual photon absorptiometry to establish patterns of bone reduction at the spine and hip. Subjects were either randomly selected from the electoral roll or volunteers. Bone mineral density reduction at the lumbar spine in females appeared to increase at 40 years and was sustained until 60 years. In males bone mineral density at the spine was preserved. The density at the hip in females decreased throughout adult life beginning before the menopause. In males bone density was preserved at the femoral neck and trochanteric region but not at Wards triangle where reduction occurred throughout life. When compared with other normal populations there was higher bone mineral density at the spine in postmenopausal New Zealand females but no significant difference at the hip.

The actions of members of the homologous series of alkyl cations CH3 (CH2)n-1 N+ (CH3)3 (Cn TMA) on the sodium current in giant axons of Loligo forbesi have been investigated. The substances tested correspond to n = 6, 8, 10, 12, 14 and 16. These cations only produced significant sodium current suppression when applied inside the axon. Actions on first-pulse sodium currents and use-dependent effects were separately studied. The shorter members of the series (C6TMA and C8TMA) produced suppression of first-pulse sodium currents without causing significant use dependence. The first-pulse suppression arose partly from a positive shift along the voltage axis of the steady-state activation parameter (m infinity) and partly from a reduction in the maximum sodium conductance (gNa). C12TMA and C14TMA produced little first-pulse suppression but caused clear use dependence. C10TMA showed intermediate properties while C16TMA was inactive. The use-dependent actions have been quantitatively investigated using a double-pulse protocol. The results are consistent with a model in which the cations enter a blocking site on the ion-channel via the intra-axonal aqueous phase. The cations appear able to bind to inactivated sodium channels at significant rates. The possible molecular locations of the sites responsible for m infinity shifts and use dependence are discussed. It is argued that the existence of two separate sites may help to explain certain distinctions between the actions of neutral general anaesthetics and clinical local anaesthetics on the sodium channel.

(1) The effects of benzocaine on the ionic currents in the voltage-clamped squid giant axon have been examined under various conditions; intact axons, axons internally perfused with CsF and axons dialysed with tetraethylammonium ions were used. (2) Both the steady state outward (potassium) current and the early transient (sodium) current were reduced by ca. 50% by benzocaine (1 mM). (3) Plots of the changes produced by benzocaine (1 mM) in the Hodgkin-Huxley parameters for the steady state activation (m infinity), the steady state inactivation (h infinity) and the time constants (tau m and tau h) for activation and inactivation of the sodium current are shown. The m infinity and h infinity curves are shifted in positive and negative directions respectively on the voltage axis. The time constants are not greatly affected. (4) In axons in which the sodium current inactivation had been largely removed by treatment with chloramine T, the sodium current was still reduced by ca. 50% by 1 mM benzocaine and the positive shift in activation remained unchanged. (5) The dependence on benzocaine concentration (for less than or equal to 2 mM) of the peak sodium current reduction and the shift in steady state inactivation have been determined. (6) It is concluded that in the squid axon the effects on inactivation are not the main reason for the reduction of the sodium current by benzocaine and that, in common with many other neutral anaesthetics, there are at least two sites at which benzocaine acts.

The effects of n-alkanes (n-pentane to n-octane), n-alkanols (n-pentanol to n-undecanol) and two carboxylic esters (methyl pentanoate and methyl octanoate) on the conductance of squid giant axons in a high potassium, zero sodium bathing solution have been examined. Sodium and delayed rectifier potassium channels were as far as possible pharmacologically blocked. A substantial fraction of the measured conductance is attributed to a recently-described, voltage-independent, potassium channel. Anaesthetics block this channel but its sensitivity is markedly different from those of other squid axon ion channels.

The effects of n-decanol, n-hexadecanol, n-octyl(oxyethylene)3 alcohol and cholesterol on gramicidin single-channel lifetime in planar lipid bilayers have been determined. The bilayers used were formed from a solution of monoolein in squalene. Measurements have also been made of the above compounds' effects on membrane thickness (as measured by electrical capacity and optical reflectance technique) and surface tension (as derived from bulk interfacial tension and bilayer-lens contact angle measurements). The reduction in single-channel lifetime caused by the n-alkanols may be accounted for quantitatively in terms of the effects of these compounds on bilayer thickness and surface tension. The n-octyl(oxyethylene)3 alcohol caused an increase in single-channel lifetime which is also consistent with the thickness/tension theory. The reduction in channel lifetime caused by cholesterol, however, was much larger than would be predicted from its effects on bilayer thickness and surface tension.

Experiments were performed to establish a procedure for in vivo measurement of nitrite utilization by leaf tissue of bean (Phaseolus vulgaris L. cv. Top Crop).To measure light-dependent nitrite disappearance, a single disc of leaf tissue was exposed to light for 1 hour at 30 C while immersed in incubation medium (approximately 0.11 milliliter per square centimeter of leaf area) in the bottom of a tall-form glass beaker. The incubation medium was 100 millimolar phosphate buffer (pH 7.5) with added wetting agent and nitrite. The wetting agent combination of 1% 1-propanol plus 0.05% Neutronyx-600 was used in some experiments for compatibility with established in vivo nitrate reductase (NR) assays; however, 0.05% Neutronyx-600 alone was found to be a suitable substitute. Parallel assays run in the dark on related tissue are recommended as a means to determine the amount of nitrite synthesized within the tissue by the NR system. Adding the results of the two assays gives an estimate of total nitrite utilization by the leaf tissue. It was found that 20 millimolar nitrite in the incubation medium was the most suitable level of external nitrite for promoting light-dependent nitrite disappearance. This was also found to reduce, sometimes to zero, the rate of synthesis of nitrite by NR. NR activity declined steadily with advancing age. Except for very young tissue, the rate of nitrite disappearance was independent of age. Nitrite disappearance was completely blocked by diuron.

The short-chain phospholipid, diheptanoyl phosphatidylcholine, at 520 microM, reduced the maximum inward sodium current in voltage-clamped squid giant axons by greater than 50%. Analysis of these currents by means of the Hodgkin-Huxley equations showed this reduction to be mainly the result of a large depolarizing shift in the voltage dependence of the steady state activation parameter, m infinity. The voltage dependence of the steady state inactivation parameter, h infinity, was also moved in the depolarizing direction and the axonal membrane capacitance per unit area measured at 100 kHz was increased. A longer chain length derivative, didecanoyl phosphatidylcholine, had no significant effect on the axonal sodium current at concentrations of 3.7 and 18.5 microM. Dioctanoyl phosphatidylcholine was intermediate in its effects, 200 microM producing approximately the same current suppression as 520 microM diheptanoyl phosphatidylcholine, together with depolarizing shifts in m infinity and h infinity. These effects may be contrasted with those of the normal and cyclic alkanes (1-3), which tend to move both m infinity and h infinity in the hyperpolarizing direction and to reduce the capacitance per unit area at 100 kHz. The above results are all consistent with the hypothesis that small hydrocarbons thicken, while short-chain phospholipids thin, the axonal membrane. Thus membrane thickness changes may be of considerable importance in determining the behavior of the voltage-gated sodium channel.

The effects of methyl butyl ketone, methyl heptyl ketone and methyl pentanoate on the sodium current of the squid giant axon have been examined. The peak inward current in intact axons was reduced reversibly by each substance. Sodium currents were recorded in intracellularly perfused axons before and during exposure to the test substances and the records were fitted with equations similar to those proposed by Hodgkin & Huxley (1952). Shifts in the voltage dependence of the steady-state activation and inactivation parameters (m infinity and h infinity), reductions in the peak heights of the activation and inactivation time constants (tau m and tau h) and changes in the maximum sodium conductance (gNa) caused by these substances have been tabulated and compared with the effects of methyl octanoate (Haydon & Urban, 1983b). Each compound shifted the voltage dependence of the steady-state inactivation parameter in the hyperpolarizing direction and that of the steady-state activation parameter in the depolarizing direction. The shifts produced by the ketones are compared with those produced by methyl pentanoate and by methyl octanoate. The possible role of an interaction between the carbonyl oxygen of the test substance and the sodium channel protein in producing the h infinity shift is discussed. The peak time constants are reduced and the voltage dependences of tau m and tau h are shifted in a direction commensurate with the shifts in steady-state properties. The maximum sodium conductance is not much affected either by the ketones or by methyl pentanoate. Large reductions in peak inward current coupled with little effect on gNa have been reported for the n-alkanols and other surface-active compounds (Haydon & Urban, 1983b). This lack of a large effect on gNa indicates that whatever direct interaction does take place between the test substance and the channel protein, it does not result in a blockage of the channel.

The electrical capacities per unit area of planar lipid bilayers formed from monoolein/n-hexadecane, monoolein/ squalane (or squalene) and monoolein/triolein have been measured in the presence of a range of n-alkanols. For monoolein/n-hexadecane bilayers, the effects of the n-alkanols are complicated but can be rationalized in terms of the likely changes in lipid chain order and the influence of the n-alkanol in the Plateau-Gibbs border. Monoolein/ squalane (or squalene) and monoolein/triolein bilayers exhibit behaviour quite different from the n-hexadecane membranes. For both the squalane and triolein bilayers the shorter chain alkanols increase the capacity per unit area while the longer homologues have little effect. These results help to account for the influence of the n-alkanols on gramicidin single-channel lifetimes.

The effects of the homologous series of carboxylic esters, methyl propionate to methyl decanoate, on the steady-state inactivation of the sodium current in squid axons have been studied. The esters moved the relationship between the inactivation parameter, h infinity, and the membrane potential in the hyperpolarizing direction, thus reducing the number of sodium channels available at the resting potential. The concentration dependence of the shift at the mid-point of the curve of h infinity against potential has been measured for all esters except decanoate, which was almost inactive. Two aspects of these concentration dependences suggest that molecular volume is an important determinant of the effectiveness of each ester. Firstly, there is a sharp decline in activity above methyl hexanoate. This cut-off in activity resembles that for hydrocarbons where it has been suggested [e.g., Haydon, D.A., Urban, B.W. 1983, J. Physiol. (London) 341:411-427] to a result from a decrease in uptake with increasing molecular volume. (Further data for the hydrocarbons n-butane to n-heptane are reported here.) Secondly, the smallest compounds, methyl propionate and methyl butyrate, are less effective than would be predicted if equal membrane concentrations of each ester produced the same shift. The aqueous concentration dependences for these esters indicate that below methyl hexanoate, as the series is descended, progressively higher membrane concentrations are required to produce a given shift. This would be expected if the volume of ester in the membrane, rather than the number of molecules, is important.(ABSTRACT TRUNCATED AT 250 WORDS)

Using an estimation of CLDL, 522 sera from 311 men and 211 women were studied. Lipoprotein phenotyping was done with and without knowledge of CLDL. Two hundred sixty-four of the 522 patients were considered abnormal without knowledge of CLDL. Interpretation was changed in 70 cases when CLDL was considered. Thirty-four were reclassified from 11B to IV because CLDL was not elevated. Thirty-three were reclassified from 11A to "slightly elevated cholesterol without other evidence of hyperlipoproteinemia" because CLDL was not elevated. Three were reclassified from normal to 11A because of elevated CLDL associated with borderline normal cholesterol.

The voltage dependence of the steady state inactivation parameter (h infinity) of the sodium current in the squid giant axon is known to be shifted in the hyperpolarizing direction by hydrocarbons and it has been suggested that the shifts arise from thickness changes in the axon membrane, analogous to those produced in lipid bilayers (Haydon, D. A., and J. E. Kimura, 1981, J. Physiol. [Lond.], 312:57-70; Haydon, D. A., and B. W. Urban, 1983, J. Physiol. [Lond.], 338:435-450; Haydon, D. A., J. R. Elliott, and B. M. Hendry, 1984, Curr. Top. Membr. Transp., 22:445-482). This hypothesis has been tested systematically by examining the effects of a range of concentrations of cyclopentane on the high-frequency capacitance per unit area both of the axonal membrane and of lipid bilayers formed from monoolein plus squalene. A similar comparison has been made for cyclopropane and n-butane, both at a pressure of 1 atm. The results are consistent with the notion that thickness increases in the axolemma produce the shifts in h infinity. Except at very high concentrations, however, the thickness changes in the lipid bilayer were too small to account for the h infinity shifts. A possible explanation of this finding is discussed.

(1). The effects of benzene and several of its derivatives on sodium currents in the voltage-clamped squid giant axon have been studied. Substances tested were benzene, aniline, benzyl alcohol, propiophenone, 4-amino-propiophenone, methyl benzoate, ethyl benzoate, and 4-amino ethyl benzoate (benzocaine). (2.) All substances tested reduced the sodium current in both intact axons and axons internally perfused with CsF. (3.) There were four major actions of benzene on the sodium current: (a) an increase in the resting level of inactivation, (b) an increase in the depolarization required to produce the maximum current, (c) a decrease in the maximum sodium conductance, and (d) an increase in the rate of inactivation. (4.) 4-amino ethyl benzoate (benzocaine) had actions on the sodium current which were very similar to those of benzene with the exception that the rate of inactivation was scarcely affected and, at comparable shifts, the slope of the steady state inactivation curve was slightly smaller. (5.) The results obtained with the substances structurally intermediate between benzene and 4-amino ethyl benzoate allow some conclusions to be drawn as to the role of each functional group.