Biochemical characterisation of the 56 and 82 kDa immunodominant gametocyte antigens from Eimeria maxima

Two immunodominant gametocyte antigens from Eimeria maxima with M(r) 56 kDa and M(r) 82 kDa have been identified previously as potential candidates for inclusion in a recombinant subunit vaccine against coccidiosis in poultry. Here, these proteins have been biochemically characterised, immunolocalised within the parasite, and sequences for their amino termini determined. These antigens co-purify by affinity chromatography suggesting an interaction with each other. However, separation of the proteins by sodium dodecyl sulphate polyacrylamide gel electrophoresis (SDS-PAGE) in the absence of beta-mercaptoethanol did not reveal the presence of inter-chain disulphide bonds. The true masses of the 56 and 82 kDa antigens are 52450 and 62450 Da, respectively, as determined by mass spectrometry. TX-114 separations suggested that they exist, in part, as soluble proteins within the parasite, and immunolocalisation studies indicated that they were found in the wall forming bodies of macrogametocytes. Separation of the proteins by 2D SDS-PAGE revealed that they are acidic in nature and heterogeneous in charge. Cleavage by neuraminidase and O-glycosidase indicated that the presence of O-linked glycans contributed to some of the charge microheterogeneity of both proteins. The absence of these O-glycans however, did not abolish antibody recognition, suggesting that the development of a recombinant subunit vaccine is possible. A more extensive investigation of the carbohydrate moieties of these proteins revealed that they also possess glucose, fucose, mannose and galactose. There was no evidence for the presence of N-linked glycans. The 56 and 82 kDa antigens were separated from a mixture of proteins in a crude gametocyte lysate by 2D SDS-PAGE, the proteins isolated, and the N-terminus amino acid sequence determined. They showed no homology to each other at the N-terminus, or to any other previously characterised protein. Characterisation of these novel proteins has provided further insights into the molecular mechanisms of gametocyte differentiation in E. maxima.

A prospective longitudinal study of growth velocity in twin pregnancy

OBJECTIVES

Fundamental research into the growth of twins is lacking. Twin growth in utero is commonly assumed to follow similar patterns of growth as that of singletons. This preliminary descriptive study on twin pregnancy aimed to define growth velocity as gestation advances, and to study if twin order, fetal sex, zygosity and chorionicity have any relationship to growth velocity.

METHODS

One hundred and sixty-two women with twin pregnancies had an ultrasound examination at fortnightly intervals from 16 weeks until delivery. Fetal measurements of biparietal diameter, abdominal circumference and femur length were performed at each examination. Growth velocity for each parameter was defined as the difference in measurements for that parameter divided by the time interval between measurements. Postnatally, zygosity and chorionicity were determined by genetic fingerprinting and inspection of the placenta, respectively.

RESULTS

Growth velocity for all parameters decreased as gestation advanced, with the downward trend more noticeable after 32 weeks. Maximum and minimum growth occurred at 22-23 weeks and 36-37 weeks, respectively. Maximum and minimum growth velocities for the abdominal circumference were 1.7 and 0.8 cm/week, respectively. Birth order, fetal sex, chorionicity and zygosity were not related to growth velocity.

CONCLUSIONS

These preliminary results suggest that growth velocity in twins decreases after 32 weeks' gestation. It appears that growth velocity is independent of birth order, fetal sex, chorionicity and zygosity.

Activity analysis of English Premiership rugby football union refereeing

Little is known about the physiological demands placed on officials during sporting activities. The purpose of this study was to ascertain the movement activities of referees during English Premiership rugby football union matches, and to determine the frequency and duration of these activities. Nine referees who were ranked in the top 20 referees in England were videotaped during a total of 19 matches. During playback of the videotapes, a single observer coded the referees' activities into one of six distinct categories (standing, walking forwards, walking backwards, jogging, running and sprinting) using a computerized video editing system (Observer Video-Pro). The referees were timed over a 20 m distance for the modes of locomotory activity, and the average velocity of the referee for each activity was used to calculate the total distance covered in each mode of activity during matches. The total distance covered during a match was (chi +/- SD) 8581 +/- 668 m. The mean percentage of total playing time spent in each activity was: standing still, 37.0 +/- 11.0%; walking forward, 29.5 +/- 7.2%; walking backward, 9.9 +/- 3.2%; jogging, 12.8 +/- 3.2%; running, 9.8 +/- 2.3%; and sprinting, 1.0 +/- 0.4%. There were a total of 672 transitions between modes of activity during a match. The results of this study suggest that refereeing top English rugby football union matches is physically demanding. Although the major physiological load is placed on the oxygen transport system, frequent sprint bouts and the associated requirements for acceleration and deceleration impose additional metabolic demands on referees. This information may be used in the design of physical training programmes to optimize performance in referees.

Supracondylar fractures of the femur in children

Nonphyseal supracondylar fractures of the femur are considered to be uncommon in children and have received little attention in the literature. A retrospective review of femoral fractures in children at the authors' institution was undertaken to ascertain the incidence of supracondylar femoral fractures, the influence of associated musculoskeletal conditions, and pitfalls of management. In this study of 102 femoral fractures, there was an incidence of 12% of supracondylar fractures. Four of 12 patients had a significant predisposing musculoskeletal condition contributing to the genesis of the fracture. Five fractures were undisplaced and easily managed. Seven displaced fractures required intervention to achieve an adequate reduction. The literature is reviewed and a classification system for these fractures is presented. Treatment options are discussed and recommendations made based on this experience.

Bisphosphonates and nephrocalcinosis in a rabbit leg lengthening model: a histological and therapeutic comparison

We performed a comparison of the effects of two bisphosphonates, pamidronate and zoledronic acid, on regenerate bone mineral content in distraction osteogenesis in an immature rabbit model. Single dose zoledronic acid was found to be 18 times more potent at producing an increase in bone mineral content than pamidronate per mg/kg of drug infused at surgery. Histological examination of all rabbit kidneys was performed at trial completion. Nephrocalcinosis was identified in 14 of 20 kidneys of rabbits infused with pamidronate, but was not detected in the 20 kidneys of those rabbits infused with zoledronic acid. A further 20 kidneys from rabbits given a second dose of zoledronic acid were also found to be free of signs of nephrocalcinosis. Three of 40 control kidneys exhibited signs of nephrocalcinosis. The increased potency of zoledronic acid allowed us to give one-tenth the dose of pamidronate, with increased therapeutic efficacy and no evidence of nephrocalcinosis.

Medical management of early fetal demise using a combination of mifepristone and misoprostol

BACKGROUND

This study aims to assess the efficacy of a combination of mifepristone and misoprostol in the management of missed miscarriage and anembryonic pregnancy.

METHODS

Data of 220 consecutive women with miscarriage, undergoing medical evacuation of the uterus were collected prospectively at an early pregnancy assessment unit in a tertiary referral hospital. Each woman received a single oral dose of mifepristone 200 mg and 36-48 h later vaginal misoprostol 800 microg. Three hours following the first dose, two further doses of misoprostol, 400 microg each, were administered vaginally or orally at 3 h intervals. Women who failed to pass products of conception were offered repeat medical regime with misoprostol. Success was defined as complete uterine evacuation within 3 days, without the need for surgical evacuation.

RESULTS

The overall success rate of medical management was 84.1%. Mifepristone alone induced natural expulsion of products of conception in 18.1% of women. The median dose of misoprostol required was 1600 microg and the median induction miscarriage interval after first prostaglandin administration was 8.04 h (range: 0.58-50.54 h). Of the 142 women who were symptomatic at presentation the medical regime failed in 30 (21.1%), compared with five (6.4%) failures of the 78 who were asymptomatic (P = 0.007). Of the 35 women who had surgical evacuation, eight required an emergency curettage for bleeding.

CONCLUSIONS

The combination of oral mifepristone 200 mg with vaginal or oral misoprostol is an alternative to surgical management of early fetal demise, although it is not as effective as surgery.

Coupling of histamine H3 receptors to neuronal Na+/H+ exchange: a novel protective mechanism in myocardial ischemia

In myocardial ischemia, adrenergic nerves release excessive amounts of norepinephrine (NE), causing dysfunction and arrhythmias. With anoxia and the concomitant ATP depletion, vesicular storage of NE is impaired, resulting in accumulation of free NE in the axoplasm of sympathetic nerves. Intraneuronal acidosis activates the Na(+)/H(+) exchanger (NHE), leading to increased Na(+) entry in the nerve terminals. These conditions favor availability of the NE transporter to the axoplasmic side of the membrane, causing massive carrier-mediated efflux of free NE. Neuronal NHE activation is pivotal in this process; NHE inhibitors attenuate carrier-mediated NE release. We previously reported that activation of histamine H(3) receptors (H(3)R) on cardiac sympathetic nerves also reduces carrier-mediated NE release and alleviates arrhythmias. Thus, H(3)R activation may be negatively coupled to NHE. We tested this hypothesis in individual human SKNMC neuroblastoma cells stably transfected with H(3)R cDNA, loaded with the intracellular pH (pH(i)) indicator BCECF. These cells possess amiloride-sensitive NHE. NHE activity was measured as the rate of Na(+)-dependent pH(i) recovery in response to an acute acid pulse (NH(4)Cl). We found that the selective H(3)R-agonist imetit markedly diminished NHE activity, and so did the amiloride derivative EIPA. The selective H(3)R antagonist thioperamide abolished the imetit-induced NHE attenuation. Thus, our results provide a link between H(3)R and NHE, which may limit the excessive release of NE during protracted myocardial ischemia. Our previous and present findings uncover a novel mechanism of cardioprotection: NHE inhibition in cardiac adrenergic neurons as a means to prevent ischemic arrhythmias associated with carrier-mediated NE release.

A test of processing efficiency theory in a team sport context

In this study, we tested some key postulates of Eysenck and Calvo's processing efficiency theory in a team sport. The participants were 12 elite male volleyball players who were followed throughout the course of a competitive season. Self-report measures of pre-match and in-game cognitive anxiety and mental effort were collected in groups of players high and low in dispositional anxiety. Player performance was determined from the statistical analysis of match-play. Sets were classified according to the point spread separating the two teams into one of three levels of criticality. Game momentum was also analysed to determine its influence on in-game state anxiety. Significant differences in in-game cognitive anxiety were apparent between high and low trait anxiety groups. An interaction between anxiety grouping and momentum condition was also evident in cognitive anxiety. Differences in set criticality were reflected in significant elevations in mental effort, an effect more pronounced in dispositionally high anxious performers. Consistent with the predictions of processing efficiency theory, mental effort ratings were higher in high trait-anxious players in settings where their performance was equivalent to that of low trait-anxious performers. The usefulness of processing efficiency theory as an explanatory framework in sport anxiety research is discussed in the light of these findings.

The production of a 70 kDa heat shock protein by Toxoplasma gondii RH strain in immunocompromised mice

A 70 kDa heat shock protein (HSP70) has been reported previously to be strongly expressed in virulent Toxoplasma gondii strains taken from immunocompetent mice but it is poorly expressed by virulent parasites in mice immunocompromised by treatment with cortisone acetate or by virulent parasites cultured in vitro. Immune factors such as interferon-gamma, tumour necrosis factor and reactive nitrogen intermediates derived from nitric oxide are known to be important inducers of HSP70 production and are also known to be produced during the immune response to acute T. gondii infection. The ability of these immune factors to induce T. gondii HSP70 production was tested by analysing HSP70 production in tachyzoites of the virulent RH strain of T. gondii recovered from mice deficient in: (1) T cells (nude mice); (2) T and B cells (SCID mice); (3) interferon-gamma receptors (interferon-gamma receptor knockout mice); and (4) tumour necrosis factor receptors (tumour necrosis factor receptor knockout mice). Parasites from nude and SCID mice produced as much HSP70 as immunocompetent mice. Likewise, T. gondii tachyzoites from mice lacking receptors for interferon-gamma or tumour necrosis factor produced HSP70 in quantities similar to wild-type mice. The ability to produce reactive nitrogen intermediates in response to T. gondii infection, as detected by elevated levels of nitrate and nitrite in sera, was normal in tumour necrosis factor receptor knockout mice but was completely lacking in interferon-gamma receptor knockout mice, indicating that reactive nitrogen intermediates are also not responsible for induction of parasite HSP70. Thus, immune factors that induce HSP70 production in mammalian cells do not appear to play primary roles in inducing HSP70 production by T. gondii.

Enhancing fitness training adherence of elite netball players: an evaluation of Maddux's revised Theory of Planned Behaviour

An intervention based on the predictions of Maddux's revised Theory of Planned Behaviour was designed to improve fitness training adherence of a group of elite netball players. The intervention consisted of a persuasive communication and time management workshop, which targeted the social cognitive constructs of the theory. We adopted a multiple baseline across-individuals design over 14 weeks with 17 elite netball players. Baseline training adherence data were collected over the first 7 weeks. The targeted social cognitive constructs were assessed at baseline, post-intervention and follow-up. Large effect sizes for changes in training adherence from baseline to post-intervention were noted for 13 players (76%). Post-intervention analysis revealed significant changes in two of the targeted variables, perceived vulnerability and attitude towards current behaviour, suggesting that the intervention was associated with cognitive changes. Data from an intervention check provided additional evidence to support the efficacy of the intervention. A follow-up assessment over an additional 7 weeks showed that players' training frequency remained improved. The results support the view that the revised Theory of Planned Behaviour can help inform interventions that enhance the training adherence of elite netball players.

Angiotensin-converting enzyme-independent angiotensin formation in a human model of myocardial ischemia: modulation of norepinephrine release by angiotensin type 1 and angiotensin type 2 receptors

Angiotensin II (Ang II) promotes norepinephrine (NE) release from cardiac sympathetic nerve endings. We assessed in a human model in vitro whether locally formed Ang II contributes to NE release in myocardial ischemia. Surgical specimens of human right atrium were incubated in anoxic conditions. After 70 min of anoxia, NE release (carrier-mediated; caused by NE transporter reversal) was 8-fold greater than normoxic release. Angiotensin-converting enzyme inhibition with enalaprilat failed to reduce anoxic NE release. In contrast, prevention of chymase-dependent Ang II formation with chymostatin, Bowman-Birk inhibitor, or alpha(1)-antitrypsin significantly inhibited anoxic, but not exocytotic, NE release. Two mast-cell stabilizers, cromolyn and lodoxamide, markedly reduced NE release, implicating cardiac mast cells as a major source of chymase. Angiotensin type 1 receptor (AT(1)R) blockade with EXP3174 inhibited NE release, whereas angiotensin type 2 receptor (AT(2)R) blockade with PD123319 did not. Interestingly, PD123319 reversed the inhibitory effect of EXP3174. Furthermore, synergisms were uncovered between EXP3174 and an AT(2)R agonist, and between EXP3174 and a Na(+)/H(+) exchanger inhibitor. Thus, angiotensin-converting enzyme-independent Ang II formation via chymase is important for carrier-mediated ischemic NE release in the human heart. Locally generated Ang II promotes NE release by acting predominantly at AT(1)Rs, which are likely coupled to the Na(+)/H(+) exchanger. Effects of Ang II at AT(2)Rs, seemingly opposite to those resulting from AT(1)R activation, are uncovered when AT(1)Rs are blocked. Because NE release is associated with coronary vasoconstriction and arrhythmias, and mast-cell density and chymase content increase in the ischemic heart, the notion that chymase-generated Ang II plays a major role in carrier-mediated NE release may have important clinical implications.

Detection of Ralstonia solanacearum strains with a quantitative, multiplex, real-time, fluorogenic PCR (TaqMan) assay

A fluorogenic (TaqMan) PCR assay was developed to detect Ralstonia solanacearum strains. Two fluorogenic probes were utilized in a multiplex reaction; one broad-range probe (RS) detected all biovars of R. solanacearum, and a second more specific probe (B2) detected only biovar 2A. Amplification of the target was measured by the 5' nuclease activity of Taq DNA polymerase on each probe, resulting in emission of fluorescence. TaqMan PCR was performed with DNA extracted from 42 R. solanacearum and genetically or serologically related strains to demonstrate the specificity of the assay. In pure cultures, detection of R. solanacearum to >/=10(2) cells ml(-1) was achieved. Sensitivity decreased when TaqMan PCR was performed with inoculated potato tissue extracts, prepared by currently recommended extraction procedures. A third fluorogenic probe (COX), designed with the potato cytochrome oxidase gene sequence, was also developed for use as an internal PCR control and was shown to detect potato DNA in an RS-COX multiplex TaqMan PCR with infected potato tissue. The specificity and sensitivity of the assay, combined with high speed, robustness, reliability, and the possibility of automating the technique, offer potential advantages in routine indexing of potato tubers and other plant material for the presence of R. solanacearum.

Histamine H(3)-receptors: a new frontier in myocardial ischemia

In protracted myocardial ischemia, sympathetic nerve endings undergo ATP depletion, hypoxia and pH(i) reduction. Consequently, norepinephrine (NE) accumulates in the axoplasm, because it is no longer stored in synaptic vesicles, and intraneuronal Na(+) concentration increases, as the Na(+)/H(+) exchanger (NHE) is activated. This forces the reversal of the Na(+)- and Cl(-)-dependent NE transporter, triggering a massive carrier-mediated release of NE and thus, arrhythmias. Indeed, NE overflow in myocardial ischemia directly correlates with the severity of arrhythmias. Histamine H(3)-receptors (H(3)R) have been identified as inhibitory heteroreceptors in adrenergic nerve endings of the heart. In addition to inhibiting NE exocytosis from sympathetic nerve endings, selective H(3)R agonists attenuate carrier-mediated release of NE in both animal and human models of protracted myocardial ischemia. Whereas H(3)R-mediated attenuation of exocytotic NE release involves an inhibition of N-type Ca(2+)-channels, H(3)R-mediated reduction of carrier-mediated NE release is associated with diminished NHE activity. In addition to inhibiting NE release, H(3)R stimulation significantly attenuates the incidence and duration of ventricular fibrillation. Although other presynaptic receptors also modulate NE release from sympathetic nerve endings, H(3)R stimulation reduces both exocytotic and carrier-mediated NE release, whereas alpha(2)-adrenoceptor agonists attenuate NE exocytosis but enhance carrier-mediated NE release. Furthermore, unlike adenosine A(1)-receptors, whose activation reduces both exocytotic and carrier-mediated NE release, H(3)R stimulation is devoid of negative chronotropic and dromotropic effects (i.e., sinoatrial and atrioventricular nodal functions are unaffected). Because excess NE release can trigger severe arrhythmias and sudden cardiac death, negative modulation of NE release by H(3)R agonists may offer a novel therapeutic approach to myocardial ischemia.

LLC-PK(1) cells stably expressing the human norepinephrine transporter: A functional model of carrier-mediated norepinephrine release in protracted myocardial ischemia

In myocardial ischemia, adrenergic terminals undergo ATP depletion, hypoxia, and intracellular pH reduction, causing the accumulation of axoplasmic norepinephrine (NE) and intracellular Na(+) [via the Na(+)-H(+) exchanger (NHE)]. This forces the reversal of the Na(+)- and Cl(-)-dependent NE transporter (NET), triggering massive carrier-mediated NE release and, thus, arrhythmias. We have now developed a cellular model of carrier-mediated NE release using an LLC-PK(1) cell line stably transfected with human NET cDNA (LLC-NET). LLC-NET cells transported [(3)H]NE and [(3)H]N-methyl-4-phenylpyridinium ([(3)H]MPP(+)) in an inward direction. This uptake was abolished by the NET inhibitors desipramine (100 nM) and mazindol (300 nM) and by extracellular Na(+) removal. Na(+)-gradient reversal induced an efflux of (3)H-substrate from preloaded LLC-NET cells. Desipramine and mazindol blocked this efflux. Because of its greater intracellular stability and higher sensitivity to Na(+)-gradient reversal, [(3)H]MPP(+) proved preferable to [(3)H]NE as an NET substrate; therefore, only [(3)H]MPP(+) was used for subsequent studies. The K(+)/H(+) ionophore nigericin (10 microM) evoked a large efflux of [(3)H]MPP(+). This efflux was potentiated by the Na(+),K(+)-ATPase inhibitor ouabain (100 microM), was sensitive to desipramine, and was blocked by the NHE inhibitor 5-(N-ethyl-N-isopropyl)-amiloride (EIPA; 10 microM). In contrast, EIPA failed to inhibit the [(3)H]MPP(+) efflux elicited by the Na(+) ionophore gramicidin (10 microM). Furthermore, [(3)H]MPP(+) efflux induced by the NHE-stimulant proprionate (25 mM) was negatively modulated by imidazoline receptor activation. Our findings suggest that LLC-NET cells are a sensitive model for studying transductional processes of carrier-mediated NE release associated with myocardial ischemia.

Cytokines, nitric oxide, heat shock proteins and virulence in Toxoplasma

Elucidating the factors that play important roles in the expression of virulence by parasites is crucial to understanding disease pathogenesis and to developing control strategies rationally. Here, Kate Miller, Nick Smith and Alan Johnson, using Toxoplasma gondii as a model, argue that the interactions between the immune system and 70 kDa heat shock proteins of apicomplexan parasites profoundly influence parasite virulence.

Metabolic effects of nitric oxide synthase inhibition during exercise in the horse

The effect of nitric oxide synthase (NOS) inhibition during exercise on lactate production was investigated in five Thoroughbred horses. A standard exercise test (SET), consisting of three canters (approximately 55 per cent VO2max), with walking and trotting between each canter, was performed twice (control and test, in random order) by each horse. Nphi-nitro-L-arginine methyl ester (L-NAME; 20 mg kg-1), a competitive inhibitor of NOS, induced a significant increase (P < 0.05) in plasma lactate [5.7 (2.9) vs 11.8 (3.8) mmol L-1], which continued to increase despite administration of L-arginine, the substrate for NOS. There were no differences in cardiac output (Q) or the total body oxygen consumption (VO) between each SET. The results show that non-specific inhibition of NOS isoforms during exercise in the horse increases plasma lactate concentration, although the mechanism/s remain uncertain.

A six year study of the antenatal detection of fetal abnormality in six Scottish health boards

OBJECTIVE

To assess the sensitivity of prenatal diagnosis by ultrasound and biochemical methods, to evaluate the reasons for non-detection and to make appropriate recommendations.

DESIGN

Six year observational study, during which biochemical screening for trisomy 21 was introduced and there was an increase in routine ultrasound scanning at 18-22 weeks.

SETTING

Six health boards in Scotland.

POPULATION

264,481 pregnancies, of which 862 were terminated because of fetal abnormality, and 2123 delivered with prenatally detectable major fetal abnormalities.

MAIN OUTCOME MEASURES

The prenatal detection of trisomies 13, 18 and 21, and 12 major structural abnormalities, which the average ultrasonographer with average skills using average equipment would be expected to detect.

RESULTS

Serum biochemical screening improved detection of trisomy 21 from 33% to 57%. The detection rate for the major abnormalities was 62% (815/1320) and 73% (598/818) when the trisomies were excluded. 18-22 weeks scanning yielded a 92% detection rate. Of the 505 undetected cases, 15% declined prenatal screening, 46% were unscreened because they were ineligible for testing, unbooked, booked too late or scanned too early for a diagnosis to be made, 2% had findings suspicious of a chromosomal abnormality but testing was not undertaken and 37% had a negative scan at a gestation when the abnormality was potentially detectable.

CONCLUSIONS

A policy of first trimester scanning followed by serum alpha-fetoprotein screening and additional scanning as clinically indicated is effective in detecting major structural abnormalities, but scanning at 18-22 weeks and serum biochemical screening for trisomy 21 improved the detection rates. Supervised training and adequate equipment are essential. Present prenatal diagnostic tests will not detect all abnormalities and patients must be made aware of this.

Nuchal thickening in Jacobsen syndrome

A routine detailed ultrasound examination performed at 20 weeks' gestation demonstrated the presence of nuchal thickening as an apparently isolated finding. The concentration of maternal alpha-fetoprotein was normal and the risk of Down's syndrome was 1 in 6800. Amniocentesis was performed and chromosome analysis showed the karyotype 46,XY, del(11)(q23) found in Jacobsen syndrome. Fetal autopsy performed following medical termination at 23 weeks confirmed the phenotype and internal abnormalities found in Jacobsen syndrome.

Immunity to Asexual Blood Stages of Plasmodium: Is Resistance to Acute Malaria Adaptive or Innate?

Current models of immunity to blood stages of Plasmodium invoke a primary role for T-cell dependent processes and much recent evidence implicates Th1-type responses as crucial to the control of acute malaria. But do these data stand up to close scrutiny? Here, Andy Fell and Nick Smith review recent data from rodent and human studies and suggest that Th1-type responses may not after all be important in controlling malaria infection in the blood.