Potassium currents and their modulation by muscarine and substance P in neuronal cultures from adult guinea pig celiac ganglia

1. Intracellular microelectrode and whole-cell patch-clamp recordings were obtained from adult guinea pig celiac ganglion neurons grown in tissue culture for 7-14 days. Over 90% of neurons showed phasic-type action-potential discharge with the use of either type of recording electrode; they stained immunohistochemically for catecholamines, tyrosine hydroxylase, and neuropeptide Y. Input resistance (140 M omega) and action-potential amplitude (103 mV) were significantly greater with whole-cell than with microelectrode recordings, but other passive electrical properties were similar. 2. Five potassium currents were characterized: an apamin-sensitive after hyperpolarizing current (IAHP), an apamin and tetraethylammonium-insensitive slow IAHP, an M-like current, a transient outward IA current, and a delayed rectifier IK current. A hyperpolarization-activated cationic Ih current was also present. The first three currents were not observed with whole-cell recordings. 3. Cadmium (200 microM), cobalt (1 mM), lanthanum (30 microM), or a low calcium/high magnesium solution blocked both IAHPS and the M-like current; barium (1 mM) also blocked these currents. 4. Kinetics of the M-like current were best described by a double exponential fit to deactivating tail currents with time constants of 50 and 390 ms at -50 mV. The apamin-sensitive and slow IAHP decayed exponentially with time constants of 145 ms and 3.5 s, respectively. There was no correlation between occurrence of M-like current (95% of neurons) and slow IAHP (40% of neurons), nor any correlation between magnitude of M-like current and IAHP in those cells exhibiting both currents. 5. Muscarine and substance P (SP) caused depolarizations or inward currents (under voltage clamp) at the resting potential (-55 mV) associated with a decreased membrane conductance. The slow IAHP and the M-like current, but not the apamin-sensitive IAHP nor the IA, were blocked by muscarine and SP (IC50 3 microM and 100 nM, respectively). Muscarine and SP also decreased a "leak" potassium current. 6. We conclude that celiac neurons express two calcium-dependent IAHP currents and a calcium-dependent M-current; these are seen by fine-tipped intracellular microelectrodes but not by whole-cell patch electrodes. These currents are not required for spike frequency accommodation. Muscarine and SP reduce these currents, as well as voltage-independent leakage potassium current.

ADP induces desensitisation of equine platelet aggregation responses: studies using ADP beta S, a stable analogue of ADP

Pre-incubation of equine platelets in platelet-rich plasma with adenosine 5'-diphosphate (ADP) induced a reduction in aggregation responsiveness to subsequent additions of ADP. The desensitisation was shown to be homologous since the responsiveness to platelet-activating factor, thrombin, collagen, 5-hydroxytryptamine or ionomycin remained unchanged. Adenosine 5'-(beta-thio)-diphosphate (ADP beta S), a non-hydrolysable analogue of ADP, was shown to act as an agonist inducing aggregation by interaction with the ADP receptor. ADP beta S was then used in the desensitisation studies in which residual ADP was degraded by the addition of apyrase. The desensitisation to ADP beta S fully recovered by one hour after pre-treatment with ADP and was not induced by an extracellular mediator. The mechanism of desensitisation is therefore likely to involve the ADP receptor or proximal intermediates in the signal transduction pathway for ADP.

Pneumomediastinum after rugby training

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To what extent do anxiety and depression interact with chronic pain?

In 61 patients with generalized musculoskeletal pain, severity of anxiety and depression correlated significantly with self-reported impact of illness and physician-rated disability. Depression was significantly associated with pain-frequency, whereas anxiety was unrelated. Depressed mood was more closely tied to patients' ability to function than to their experience of pain.

A method for loading equine platelets with the fluorescent calcium indicator Fura-2: ADP induces a rise in the cytosolic free calcium ion concentration

Equine platelets in platelet-rich plasma were incubated with the fluorescent indicator dye, Fura-2-AM (Fura-2-acetoxymethyl ester) and the degree of loading of the cells with the dye and the extent of hydrolysis of the ester was assessed by quantitative fluorimetry and by thin-layer chromatography respectively. Under these conditions the cells loaded poorly with Fura-2 to a concentration of 4 microM. The technique was validated by demonstrating adequate loading of human platelets with Fura-2, to a concentration of 250-300 microM, using the same method. The removal of plasma from the extracellular medium was important for successful loading of the cells with the dye since washed cells resuspended in a physiological salt solution loaded adequately with Fura-2 to a concentration of 190 microM. Cells loaded as such showed a resting [Ca2+]i of 129 nM and a concentration-dependent rise in [Ca2+]i to a transient maximum of 350 nM when stimulated by the pro-aggregatory agonist adenosine 5'-diphosphate (ADP).

A survey of basic resuscitation knowledge among resident paediatricians

A telephone questionnaire was undertaken to evaluate the knowledge of resident paediatricians on the subject of the basic resuscitation of the acutely sick child. The questionnaire was targeted at 88 resident paediatricians in hospitals accepting paediatric emergencies in four health regions. Outcome was measured as a correct response to questions based on several emergency scenarios and on the confidence expressed of basic resuscitation knowledge. The subject of emergency management of the child with a compromised upper airway was poorly answered with 40/73 (55%) resident paediatricians suggesting an incorrect endotracheal tube size for an 8 year old child. Fluid management was also deemed unsatisfactory with only 36/73 (49%) providing adequate transfusion secondary to haemorrhagic shock. In addition only 19/73 (26%) mentioned the intraosseous route as a means of obtaining vascular access in a child in extremis. Confidence of the knowledge of basic resuscitation of children was low among resident paediatricians with only 30/73 (41%) expressing confidence and 69/73 (94%) expressing a desire for more formal training in paediatric resuscitation. Resident paediatricians are usually the key personnel in the management of very sick children. This survey demonstrates a low level of basic resuscitation knowledge among resident paediatricians of all grades that must be remedied at a local and national level.

Vasoconstriction of guinea-pig submucosal arterioles following sympathetic nerve stimulation is mediated by the release of ATP

1. The nature of the transmitter mediating vasoconstriction of guinea-pig submucosal arterioles following sympathetic nerve stimulation was studied. 2. Prazosin (0.1 microM) abolished the response to exogenously applied phenylephrine (1 microM) but had no effect on constrictions of submucosal arterioles evoked by nerve stimulation (100 pulses at 10 Hz). 3. Vasoconstrictions and excitatory junction potentials elicited by nerve stimulation were potentiated by idazoxan (0.1 microM). 4. Following reserpine treatment, catecholamine fluorescence was absent in submucosal arterioles but nerve-evoked vasoconstrictions were unaltered. 5. Vasoconstrictions and excitatory junction potentials recorded in response to sympathetic nerve stimulation, as well as constrictions evoked by exogenously applied ATP (3 microM), were abolished by the P2-purinoceptor antagonist, suramin (100 microM). Suramin had no effect on the vasoconstriction in response to noradrenaline (3 microM), or the nicotinic excitatory postsynaptic potentials (e.p.s.ps) and noradrenergic inhibitory postsynaptic potentials (i.p.s.ps) recorded from submucosal neurones. 6. We conclude that postjunctional responses of submucosal arterioles following sympathetic nerve stimulation are mediated solely through the activation of P2X-purinoceptors by ATP or a related purine nucleotide. The function of neurally released noradrenaline is to act through prejunctional alpha 2-adrenoceptors to depress transmitter release.

Exposure of the hands to ionizing radiation in the resuscitation room of an accident & emergency department

Exposure of the hands to ionizing radiation in the resuscitation room of an A&E department was measured in eight health care personnel over 3 consecutive months. The radiation levels did not exceed those limits currently recommended by the International Commission on Radiological Protection 1990. The level recorded in one individual did exceed the level set at the Lothian Health Boards investigation limit. In only five of 85 occasions were lead gloves worn by the doctor during cross table lateral cervical radiographs. Recommendations are made for reducing the radiation exposure to the hands.

ATP mediates fast synaptic transmission in mammalian neurons

In addition to its diverse functions inside cells, ATP can act at several types of cell-surface receptor. One of these (P2X-purinoceptor) is believed to be a ligand-gated cation channel. The presence of P2X receptors on autonomic, sensory and central neurons suggests that ATP might be released to act as a fast excitatory synaptic transmitter. Here we record excitatory synaptic potentials and currents from cultured coeliac ganglion neurons which are mimicked by ATP, blocked by the P2-purinoceptor antagonist suramin, desensitized by alpha,beta-methylene-ATP and unaffected by antagonists acting at nicotine, 5-hydroxytryptamine, N-methyl-D-aspartate (NMDA), non-NMDA glutamate, gamma-aminobutyric acid (GABA), noradrenaline or adenosine receptors. We conclude that ATP is the neurotransmitter at this neuroneuronal synapse.

Variation among trainee surgeons in interpreting diagnostic peritoneal lavage fluid in blunt abdominal trauma

Diagnostic peritoneal lavage is useful in selected patients who have sustained blunt abdominal trauma. The way in which 50 trainee surgeons (37 registrars and 13 senior registrars) perform and interpret diagnostic peritoneal lavage was investigated in this study by a simple questionnaire followed by assessment of simulated lavage fluid. This exposed misconceptions about interpretation of diagnostic peritoneal lavage fluid and a reliance upon visual assessment. Assessment of the simulated lavage fluid revealed a wide range of thresholds for a positive result (2460-48,700 red blood cells/mm3), although 49 surgeons (98%) had lower thresholds than that generally recommended. Senior registrars had significantly higher thresholds than registrars, implying a learning curve involving unnecessary laparotomies. In order to avoid this situation and to detect injuries that might otherwise be missed, trainee surgeons are recommended to perform cell count analysis routinely on diagnostic peritoneal lavage fluid.

Relative contributions of ATP and noradrenaline to the nerve evoked contraction of the rabbit jejunal artery. Dependence on stimulation parameters

Isotonic contractions of the rabbit jejunal artery were evoked by perivascular nerve stimulation with trains of 10 or 100 stimuli at 2 Hz or 10 Hz. Short trains of stimuli elicited contractions that were totally resistant to alpha-adrenoceptor blockade (0.1 mumol/l prazosin) but blocked by alpha,beta-methylene ATP (1 mumol/l). A substantial noradrenergic component of contraction comprising about 50% of the total could be evoked by adjusting the stimulation parameters (increasing the frequency and/or number of stimuli in a train). The noradrenergic and the purinergic components are derived from sympathetic nerves as both were blocked by TTX and the adrenergic neurone blocker guanethidine (3 mumol/l). It is concluded that the contraction of the rabbit jejunal artery to short trains of stimuli is predominantly purinergic, a noradrenergic component only being revealed at higher frequencies of stimulation or during longer trains of stimuli. The purinergic component of contraction is derived from sympathetic nerves and not from a separate population of purinergic nerves.

Variable inactivation of human factor VIII from different sources by human factor VIII inhibitors

The source of human factor VIIII (FVIII) had a marked effect on the inhibitory activity of a panel of eight human FVIII inhibitors. Use of conventional FVIII concentrates gave lower inhibitor titres whereas a monoclonal antibody purified FVIII concentrate gave titres similar to or greater than those with plasma. Addition of phospholipid (PL) protected highly purified FVIII against inhibition. The content of PL-bound FVIII in concentrates may account for the observed differences.

Genomic structure of the human Ig lambda 1 gene suggests that it may be expressed as an Ig lambda 14.1-like protein or as a canonical B cell Ig lambda light chain: implications for Ig lambda gene evolution

In pre-B cells, immunoglobulin mu (Ig mu) is associated with pre-B cell-specific proteins to form a multimeric complex that is found on the cell surface. One of these proteins is encoded by the three exon Ig lambda-like gene 14.1, whose expression is restricted to pre-B cells and occurs from an unrearranged gene. A comparison of the 14.1 gene structure to the seven-gene human Ig lambda locus revealed that the most 5' gene, Ig lambda 1, is organized in a three-exon structure very similar to the 14.1 gene. Transcription and splicing of these three-exon sequences would lead to an mRNA with an open reading frame which could encode a light (L) chain-like protein with a molecular weight of 23,045. Our analysis suggests that two transcripts may be produced from the Ig lambda 1 gene that share the same Ig lambda 1 constant region-containing third exon. One transcript would include all three 14.1-related exons and be expressed from the germline gene, and the second transcript would be produced after variable-joining (V-J) recombination has occurred to Ig lambda J1 and would encode a classic Ig lambda L chain protein. The conservation of the genomic organization of the human 14.1 and Ig lambda 1 genes and the mouse homolog, lambda 5, relative to the classic Ig lambda L chain genes provides insight into the evolution of Ig genes.

Post-herpetic neuralgia: further post-mortem studies of cases with and without pain

The pathological features associated with post-herpetic neuralgia require further study. We report here 5 cases, 3 with severe post-herpetic neuralgia (PHN) and 2 with no persistent pain. The findings of dorsal horn atrophy and cell, axon and myelin loss with fibrosis in the sensory ganglion were found only in patients with persistent pain. Marked loss of myelin and axons in the nerve and/or sensory root were found in cases with and without pain. Some evidence is presented for a more generalized subacute or chronic inflammatory process which may explain the clinical features of some patients. Further studies will be necessary to fully describe the morbid anatomy of this disorder.

Blood biochemical reference ranges for sows under modern management conditions

Published reference ranges for blood biochemistry in swine generally do not relate to sows in modern breeding units, and results were often obtained by methods that are now outdated. The ranges widely used in clinical practice reflect these inappropriate sources. The data presented here were obtained using modern methods of analysis on blood samples from healthy, conventionally managed sows from six breeding herds of known disease status in eastern England, and thus represent appropriate ranges for this class of swine. The values differ from earlier reports principally in higher values for total bilirubin, creatine kinase, and more particularly of total plasma and serum proteins. The latter are shown to be due to higher immunoglobulin concentrations than those previously reported.

Effects of aspirin on xylazine-induced hypoxaemia in sheep

Aspirin (10 mg kg-1) administered intravenously to conscious sheep four hours before intravenous xylazine injection (50 micrograms kg-1), failed to abolish or attenuate the hypoxaemic effect of xylazine in this species. Serum thromboxane levels measured in one animal revealed that aspirin administered in this way reduced serum thromboxane levels by 95 per cent. Xylazine (3 x 10(-5) M--4 x 10(-3) M) failed to induce platelet aggregation in vitro. It appears that the mechanism whereby xylazine causes arterial hypoxaemia in sheep does not involve a cyclo-oxygenase-dependent aggregation of platelets.

Primary structure and functional expression from complementary DNA of a human interleukin-1 receptor antagonist

Human monocytes induced with adherent IgG secrete an interleukin-1 receptor antagonist which could be important for the in vivo regulation of IL-1 activity. A complementary DNA for this molecule has been isolated from a human monocyte library. Analysis of monocyte RNA indicates that the gene is transcriptionally regulated. The sequence of the receptor antagonist indicates that it is structurally similar to IL-1 beta. Expression of the cDNA in Escherichia coli yields IL-1 receptor antagonist activity.

A combined deficiency of factor VIII and contact activation defect in a family of cats

The coagulation parameters of a litter of kittens born to an obligate carrier of haemophilia A (classical haemophilia, factor VIII deficiency) are described. Three of four kittens were found to have an intrinsic coagulation defect, but only one was haemophilic. Factor XII deficiency was confirmed in one female, the other female and the dam being carriers of the defect. A confirmed haemophilic male from a previous litter was also found to be a factor XII deficient carrier.

Species-specific toxic effects of alpha-chlorohydrin and 6-chloro-6-deoxyglucose on astrocytes

In 1969 alpha-chlorohydrin was reported to have a reversible antifertility effect in male rats. It has since been reported to have a reversible antifertility effect in many other species but not in mice and rabbits. In chronic high-dosage regimens it was reported to be neurotoxic to mice. At high doses the 6-chloro-6-deoxysugars were found to have a reversible, complete antifertility effect. 6-Chloro-6-deoxyglucose had an antifertility effect in rats and marmosets but not in mice, hamsters, guinea-pigs or rabbits. However, repeated high doses were found to be neurotoxic in the mouse and marmoset, the most prominent pathological feature being vacuolation of astrocytes. In the studies reported here the ability of alpha-chlorohydrin and 6-chloro-6-deoxyglucose to induce vacuolation of mouse astrocytes has been confirmed in vitro. The failure of either agent to induce vacuolation of rat astrocytes suggests that both the antifertility effect of these agents and their neurotoxic effects are species-specific. The lack of correlation between neurotoxic and antifertility effects of such agents suggests that in vitro techniques may aid the development of a safe, reversible male antifertility agent and also aid in the design of further agents for rodent control.

Genomic structure of murine beta-1,4-galactosyltransferase

We have isolated a series of overlapping murine genomic DNA clones that include the complete coding sequence of the Golgi membrane bound marker enzyme beta-1,4-galactosyltransferase. The coding sequence is distributed into six exons spanning 50,000 b.p. of mouse chromosome 4. The COOH terminal domain is predominantly encoded by exons 2-6 and the transmembrane and amino terminal cytoplasmic domains are encoded by exon 1. S1 analysis establishes the most 5' transcriptional initiation site 190 b.p. upstream of the first methionine residue.