Minimizing process induced prooxidant stresses

The adverse effects of trace metals, heat, steam and other conditions encountered in food processing relate to the acceleration of development of rancidity. Measures to retard oxidation of lipids, vitamins, pigments and proteins include elimination of prooxidants, removal of oxygen and use of blends of inhibitors formulated for specific substrates.

Identification of a P2X1 purinoceptor expressed on human platelets

It has been proposed that platelets possess a P2X1-purinoceptor-like ligand-gated cation channel, through which Ca2+ enters platelets from the extracellular medium upon ADP or ATP stimulation. In this paper we describe the cloning of human P2X1-specific cDNA from human platelets, K562 and human erythroleukaemic cell lines. Sequence analyses of these cDNAs show 100% nucleotide sequence identity with that of human P2X1 cloned from urinary bladder. Western blotting of platelet lysates separated by SDS-PAGE and probed with anti-P2X1 IgG shows the expected protein with a molecular mass of 60 kDa and a second protein of 45 kDa. These data confirm that platelets possess at least two distinct purinoceptors: a P2T purinoceptor which mediates platelet aggregation, inhibition of adenylate cyclase, and release of intracellular Ca2+ stores and a platelet P2X1 purinoceptor which upon ATP and ADP stimulation mediates the rapid entry of extracellular Ca2+ into platelets.

The impact of nationally distributed guidelines on the management of paracetamol poisoning in accident and emergency departments. National Poison Information Service

OBJECTIVE

To assess the impact of the treatment guidelines on the management of paracetamol self poisoning in accident and emergency (A&E) departments.

METHODS

24 A&E departments in Wales and England provided details of their management of paracetamol poisoning before and after the distribution of national treatment guidelines to all A&E departments in the United Kingdom.

RESULTS

Significant increases were seen in the availability of formal written policies, the display of treatment nomograms, the recommendation to treat beyond 16 hours after ingestion, and to use a lower line on the treatment nomogram for patients at special risk of paracetamol induced liver damage.

CONCLUSIONS

Regularly updated guidelines in the management of paracetamol poisoning should be displayed in A&E departments so that medical and nursing personnel have access to the best current information on the treatment of poisoning with this frequently used drug.

Fracture incidence in England and Wales: a study based on the population of Cardiff

Despite the importance of fractures as an economic and health problem, and consequent interest in osteoporosis, few workers have previously attempted to define the overall incidence of fracture. This population based study was based in the Accident and Emergency Department of Cardiff Royal Infirmary and identified all patients presenting with fractures of any type. Over a single year a total of 6467 fractures were identified among the 306,600 people who live in the city of Cardiff. This gives an overall fracture incidence of 21.1/1000/year, (23.5/1000/year in males and 18.8/1000/year in females); a result very similar to those from similar work in the USA, Australia and Norway. This result is over twice the previous estimate of fracture incidence in the UK; the figure of 9/1000/year from the only equivalent study performed since the 1960s. In part, this discrepancy appears to reflect our more rigorous definition of the study population, and our improved ascertainment of minor fractures. We believe our result to offer the most accurate estimate of fracture incidence currently available for a UK population.

Managing animal bite wounds

A review of specific features associated with bite wounds occurring as a result of human fights or attacks by dogs and other animals

Ionic permeability of, and divalent cation effects on, two ATP-gated cation channels (P2X receptors) expressed in mammalian cells

1. Complementary DNAs for the ATP-gated ion channel subunits P2X1 (from human bladder) and P2X2 (from rat phaeochromocytoma (PC12) cells) were used to express the receptors in human embryonic kidney cells by stable transfection, and in Chinese hamster ovary cells by viral infection. 2. Membrane currents evoked by ATP were recorded by the whole-cell patch clamp method. The reversal potential of the current was measured with various intracellular and extracellular solutions and used to compute the relative permeability of the P2X receptor channels. 3. There was no difference between the two receptors with respect to their permeability to monovalent organic cations. The relative permeabilities (PX/PNa) were 2.3, 1.0, 1.0, 0.95, 0.72, 0.5, 0.29, 0.16, 0.04 and 0.03 for guanidinium, potassium, sodium, methylamine, caesium, dimethylamine, 2-methylethanolamine, tris(hydroxymethyl)-aminomethane, tetraethylammonium and N-methyl-D-glucamine, respectively (values for P2X2 receptor). 4. The calcium permeability of P2X1 receptors was greater than that of P2X2 receptors. Under biionic conditions (112 mM calcium outside, 154 mM sodium inside), PCa/PNa values were 3.9 and 2.2, respectively (corrected for ionic activities). 5. ATP-evoked currents in cells expressing the P2X2 receptor were strongly inhibited when the extracellular calcium concentration was increased (0.3-30 mM); the action of ATP could be restored by increasing the ATP concentration. ATP-evoked currents in cells expressing the P2X1 receptor were not inhibited by such increases in the extracellular calcium concentration.

The role of ADP in endotoxin-induced equine platelet activation

We have shown previously that endotoxin induces platelet aggregation in equine heparinised whole blood in a platelet-activating factor (PAF; 1-O-alkyl-2-acetyl-sn-glycero-3-phosphocholine) dependent manner. ADP is an agonist of platelets and is present in platelet dense granules with ATP in high concentrations. An investigation was carried out to establish whether endotoxin-induced platelet activation was associated with release of platelet ATP and ADP. ADP-scavenging enzyme systems significantly inhibited endotoxin-induced aggregation. Plasma levels of adenine nucleotides were measured using a luminometric assay following incubation of heparinised equine whole blood with endotoxin (300 ng/ml). After addition of endotoxin ATP and ADP were released from the platelets and then subsequently degraded to AMP. WEB2086 (4-[3-[4-(o-chlorophenyl)-9-methyl-6H-thieno[3,2-f]-s-triazolo[4,3-a][1, 4] diazepin-2-yl]proprionyl]-morpholine) (100 nM), a competitive PAF receptor antagonist, inhibited endotoxin-induced aggregation and also inhibited the release of adenine nucleotides from the platelets. It is concluded that endotoxin-induced aggregation is dependent upon ADP released from platelet dense granules.

Posttraumatic stress disorder and motor vehicle accidents: a multidisciplinary overview

OBJECTIVE

Motor vehicle accidents (MVA) may result in intractable disability. This paper investigates posttraumatic stress disorder (PTSD) as a potential cause.

METHOD

The literature was reviewed for recent studies on prevalence, symptom profile, and outcome of PTSD.

RESULTS

PTSD is prevalent in roughly 10% of survivors of MVAs during the first year. Comorbid depression and pain are common. Medical complications, psychophysiological reactivity, and possibly litigation may slow remission. Phobic symptoms can persist for years. Mood disturbance may augment the impact of pain on daily living and on self-perceived disability.

CONCLUSION

Recently developed screening instrument, structured interviews, and behavioural approach tests yield quantitative and reliable assessments of symptom severity. Cognitive-behavioural intervention and antidepressants may improve coping, ease fear, and reduce the impact of pain.

Single channel properties of ATP-gated cation channels (P2X receptors) heterologously expressed in Chinese hamster ovary cells

The single channel properties of four P2X receptors heterologously expressed in Chinese hamster ovary cells were determined from outside-out patch recordings. P2X1 and P2X4 channels opened in brief flickery bursts with conductances of approximately 18 and 9 pS respectively. P2X2 receptors had a single channel conductance of approximately 21 pS. Openings of P2X3 channels were too rapid to be reliably resolved. Application of ATP to macro-patches expressing multiple P2X2 or P2X4 receptors evoked sustained currents, in contrast responses of P2X1 or P2X3 receptors desensitised during continued agonist application. These data show that four different homomeric P2X receptors form ion channels with distinct single channel properties.

Stingray injury

A case of stingray injury is reported. Local symptoms and signs include intense pain, oedema around the wound, erythema and petechiae. Systemic symptoms and signs include nausea and vomiting, muscle cramps, diaphoresis, syncope, headache, muscle fasciculations, and cardiac arrhythmias. Treatment aims to reverse local and systemic effects of the venom, alleviate pain, and prevent infection. Antitetanus prophylaxis is important. Treatment for anaphylaxis may be necessary.

Platelet-activating factor and not thromboxane A2 is an important mediator of endotoxin-induced platelet aggregation in equine heparinised whole blood in vitro

Endotoxin has previously been shown to induce platelet aggregation in equine heparinised whole blood. This study aimed to determine whether platelet-activating factor or products of cyclo-oxygenase metabolism (thromboxane A2 or prostaglandins) were important in mediating the response of platelets to endotoxin. The effects of the following drugs on endotoxin-induced aggregation were investigated: aspirin, flunixin meglumine and carprofen (non-steroidal anti-inflammatory drugs); CV-3988 and WEB2086 (platelet-activating factor receptor antagonists); quinacrine (phospholipase A2 inhibitor). The effects of quinacrine on platelet aggregation in citrated platelet-rich plasma induced by ADP and platelet-activating factor were also investigated. CV-3988 and WEB2086 caused a concentration-dependent inhibition of endotoxin-induced aggregation. The non-steroidal anti-inflammatories were without effect except flunixin meglumine which produced a small inhibition of endotoxin-induced aggregation. Quinacrine had a similar effect to the platelet-activating factor antagonists, but also non-competitively inhibited platelet aggregation in citrated platelet-rich plasma. It is concluded that platelet-activating factor is a critical mediator of endotoxin-induced platelet aggregation in the horse, but that products of cyclo-oxygenase metabolism are not of importance.

An unusual death due to screwdriver impalement: A case report

A worker died after a witnessed fall from an 8-foot ladder. Autopsy revealed an unexpected penetrating wound to the hard palate. This report details the importance of the forensic autopsy in reevaluating the scene.

Development and preliminary evaluation of VISLAN, a surgical planning and guidance system using intra-operative video imaging

VISLAN is an integrated neurosurgical planning and guidance system. New segmentation and rendering techniques have been incorporated. A stereo video system is used intra-operatively and fulfils four roles. First, the video display is overlaid with graphical outlines showing the position of the planned craniotomy or the target (enhanced reality displays). Second, a skin surface patch is reconstructed from the stereo video images using patterned light (mean errors of surface point location are < 0.15 mm). Third, a freely mobile, hand-held localizer is tracked in real time (position errors are < 0.5 mm and with improved calibration < 0.2 mm), with its position superimposed on the pre-operative patient representation to assist surgical guidance. Fourth, markers fixed to the skull bone next to the cranial opening are used to detect intra-operative movement and to update registration. Initial results from phantom experiments show an overall system accuracy of better than 0.9 mm for intra-operative localization of features defined in pre-operative images. The prototype system has been tested during six neurosurgical operations with very good results.

Weever fish stings: a report of two cases presenting to an accident and emergency department

Two patients are described who suffered weever fish stings and presented to an accident and emergency department. The characteristic symptoms and treatment are described.

Mass spectrometric studies of the thermal decomposition of carbohydrates using 13C-labeled cellulose and glucose

The mechanism of the thermal decomposition of carbohydrates is very important to the development of fuels, fibers, and paper products. To help gain more insight into the pyrolysis chemistry of cellulose, we have carried out experimental studies using Acetobacter xylinum cellulose grown on D-(1-13C)-glucose medium with incorporation levels of 1-13C of 14%, as determined by 13C NMR analysis. Samples of the labeled cellulose, as well as D-(1-13C)- and D-(2-13C)-glucose, were pyrolyzed under fast-heating conditions and the products analyzed by molecular beam mass spectrometry (MBMS). From the labeled cellulose samples, statistically significant levels of enrichment were observed for the pyrolysis products that occur at m/z 110, 114, 126, 144, and 191, but not at m/z 98, 60, or 31. The lack of enrichment in the latter fragments indicates that they do not incorporate C-1. Samples were treated with 0.1% aqueous KOH to favor the formation of glycolaldehyde, but even in this case this major product was not enriched. These results suggest that the m/z 60 ion is an EI fragment ion of levoglucosan, formed by loss of neutral species containing C-1. However, the m/z 191 ion was found to contain two C-1 carbons. Collision-induced dissociation results for this ion suggest that it consists of a formate group. The structure of this ion is proposed to be the protonated formate of levoglucosan at the C-4 position, derived from either a reverse aldol reaction or a (+/-)-Diels-Alder reaction. The (1-13C)-glucose pyrolysis product distribution is similar to that for (1-13C)-labeled cellulose. The (2-13C)-glucose pyrolysis product distribution shows significant contribution from C-2 at the M + 1 peaks of m/z 32, 43, 60, 73, 85, and 97, indicating major incorporations of C-2 in glycolaldehyde in contrast to the lack of incorporation of the C-1 position in this major product.

Differential effects of CTLA-4 substitutions on the binding of human CD80 (B7-1) and CD86 (B7-2)

CTLA-4 expressed on activated T cells binds to CD80 (B7-1) and CD86 (B7-2) molecules present on APC with high avidity and appears to deliver a negative regulatory signal to the T cell. We have investigated the kinetics of CTLA-4 binding to CD80 and CD86, together with the effects of selected CTLA-4 mutations on binding activity. The dissociation constants (Kd) for binding of CTLA-4-Ig to CD80 and CD86 transfectants were 8.1 and 6.7 nM, respectively. Surface plasmon resonance was used to determine kinetic parameters of CTLA-4-Ig binding to CD80-Ig and CD86-Ig fusion proteins and revealed enhanced association (ka) and dissociation (kd) rate constants for CD86-Ig compared with CD80-Ig. Furthermore, CD80-Ig and CD86-Ig fusion molecules demonstrated variable abilities to cross-compete for binding to several modified forms of CTLA-4-Ig. Differential binding of CD80 and CD86 to CTLA-4 was further revealed by analysis of 10 discrete CTLA-4 mutants. Five single amino acid substitutions within the CTLA-4 MYPPPY domain exerted modest effects on CD80 binding, but each of these substitutions completely abrogated CD86 binding. In addition, substitutions just N-terminal of the MYPPPY region, and within the CDR1-like region of CTLA-4, eliminated both CD80 and CD86 binding. Hence, CD80 and CD86 bind with different association/dissociation kinetics to similar, but distinct, sites on CTLA-4.

Applications of the bacteriocin, nisin

Nisin was first introduced commercially as a food preservative in the UK approximately 30 years ago. First established use was as a preservative in processed cheese products and since then numerous other applications in foods and beverages have been identified. It is currently recognised as a safe food preservative in approximately 50 countries. The established uses of nisin as a preservative in processed cheese, various pasteurised dairy products, and canned vegetables will be briefly reviewed. More recent applications of nisin include its use as a preservative in high moisture, hot baked flour products (crumpets) and pasteurised liquid egg. Renewed interest is evident in the use of nisin in natural cheese production. Considerable research has been carried out on the antilisterial properties of nisin in foods and a number of applications have been proposed. Uses of nisin to control spoilage lactic acid bacteria have been identified in beer, wine, alcohol production and low pH foods such as salad dressings. Further developments of nisin are likely to include synergistic action of nisin with chelators and other bacteriocins, and its use as an adjunct in novel food processing technology such as higher pressure sterilisation and electroporation. Production of highly purified nisin preparations and enhancement by chelators has led to interest in the use of nisin for human ulcer therapy, and mastitis control in cattle.

Differential effects of CTLA-4 substitutions on the binding of human CD80 (B7-1) and CD86 (B7-2)

CTLA-4 expressed on activated T cells binds to CD80 (B7-1) and CD86 (B7-2) molecules present on APC with high avidity and appears to deliver a negative regulatory signal to the T cell. We have investigated the kinetics of CTLA-4 binding to CD80 and CD86, together with the effects of selected CTLA-4 mutations on binding activity. The dissociation constants (Kd) for binding of CTLA-4-Ig to CD80 and CD86 transfectants were 8.1 and 6.7 nM, respectively. Surface plasmon resonance was used to determine kinetic parameters of CTLA-4-Ig binding to CD80-Ig and CD86-Ig fusion proteins and revealed enhanced association (ka) and dissociation (kd) rate constants for CD86-Ig compared with CD80-Ig. Furthermore, CD80-Ig and CD86-Ig fusion molecules demonstrated variable abilities to cross-compete for binding to several modified forms of CTLA-4-Ig. Differential binding of CD80 and CD86 to CTLA-4 was further revealed by analysis of 10 discrete CTLA-4 mutants. Five single amino acid substitutions within the CTLA-4 MYPPPY domain exerted modest effects on CD80 binding, but each of these substitutions completely abrogated CD86 binding. In addition, substitutions just N-terminal of the MYPPPY region, and within the CDR1-like region of CTLA-4, eliminated both CD80 and CD86 binding. Hence, CD80 and CD86 bind with different association/dissociation kinetics to similar, but distinct, sites on CTLA-4.

Paediatricians' knowledge of cardiac arrest guidelines

A telephone questionnaire was undertaken on middle grade trainee paediatricians to test their knowledge of European Resuscitation Council guidelines. Fifty seven responded of whom only 15 (26%) offered a correct sequence of management for asystole and eight (14%) failed to identify adrenaline in their management. For ventricular fibrillation only 18/57 (32%) identified a correct sequence and very poor specific knowledge was identified. Paediatricians will under perform in the event of cardiac arrest in children without improved training in resuscitation.