Martin Cox

A Magneto-Optic Route toward the In Vivo Diagnosis of Malaria: Preliminary Results and Preclinical Trial Data

We report the development of magneto-optic technology for the rapid quantitative diagnosis of malaria that may also be realizable in a noninvasive format. Hemozoin, the waste product of malarial parasitic action on hemoglobin, is produced in a form that under the action of an applied magnetic field gives rise to an induced optical dichroism characteristic of the hemozoin concentration. Here we show that precise measurement of this induced dichroism may be used to determine the level of malarial infection because this correlates, albeit in a complex manner throughout the infection cycle, with the concentration of hemozoin in the blood and tissues of infected patients. Under conservative assumptions for the production of hemozoin as a function of parasitemia, initial results indicate that the technique can match or exceed other current diagnostic techniques. The validity of the approach is confirmed by a small preliminary clinical trial on 13 patients, and measurements on live parasitized cells obtained from in vitro culture verify the possibility of producing in vivo diagnostic instrumentation.

Chewing gum moderates multi-task induced shifts in stress, mood, and alertness. A re-examination

The finding that chewing gum can moderate stress and mood changes following a multi-task cognitive stressor (Scholey et al., 2009) was re-examined. In a repeated measures cross-over design, thirty participants completed a 20-min multi-tasking stressor on consecutive days, both with and without chewing gum. Both prior to and post stressor, participants provided salivary cortisol samples and self-rated measures of stress, state anxiety, calmness, contentedness, and alertness. Contrary to Scholey et al. (2009), chewing gum failed to attenuate both salivary cortisol levels and the increase in self-rated stress. Self-rated anxiety, calmness, and contentedness were not impacted by chewing gum. This suggests that the stress effects reported by Scholey et al. may be constrained by particular features of that study (e.g. morning testing). However, consistent with Scholey et al. (2009), chewing gum was shown to increase alertness following the stressor. The mechanisms underpinning heightened alertness are unclear; however, such increases may be linked to greater cerebral activity following the chewing of gum (Fang Li, Lu, Gong, & Yew, 2005).

The contrasting physiological and subjective effects of chewing gum on social stress

Uncertainty exists with respect to the extent to which chewing gum may attenuate stress-induced rises in cortisol secretion (Johnson, Jenks, Miles, Albert, & Cox, 2011; Scholey et al., 2009; Smith, 2010). The present study used the Trier Social Stress Task (TSST: Kirschbaum, Pirke, & Hellhammer, 1993), a task known to elevate cortisol secretion (Kudielka, Schommer, Hellhammer, & Kirschbaum, 2004), in order to examine the moderating physiological and subjective effects of chewing gum on social stress. Forty participants completed the TSST either with or without chewing gum. As expected, completion of the TSST elevated both cortisol and subjective stress levels, whilst impairing mood. Although gum moderated the perception of stress, cortisol concentrations were higher following the chewing of gum. The findings are consistent with Smith (2010) who argued that elevations in cortisol following the chewing of gum reflect heightened arousal. The findings suggest that chewing gum only benefits subjective measures of stress. The mechanism remains unclear; however, this may reflect increased cerebral blood flow, cognitive distraction, and/or effects secondary to task facilitation.

The effect of badminton-specific exercise on badminton short-serve performance in competition and practice climates.

Abstract This study examined the effects of changes in physiological and psychological arousal on badminton short-serve performance in competitive and practice climates. Twenty competitive badminton players (10 males and 10 females) volunteered to participate in the study following ethics approval. After familiarisation, badminton short-serve performance was measured at rest, mid-way through and at the end of a badminton-specific exercise protocol in two conditions; competition vs. practice. Ratings of cognitive and somatic anxiety were assessed at three time points prior to badminton short-serve performance using the Mental Readiness Form 3. Heart rate and rating of perceived exertion (RPE) were assessed during the exercise protocol. Results indicated that better short-serve performance was evident in practice compared to competition (P = .034). RPE values were significantly higher in the competition condition compared to practice (P = .007). Cognitive anxiety intensity was significantly lower post-exercise in the practice condition compared to competition (P = .001). Cognitive anxiety direction showed greater debilitation post-exercise in the competition condition compared to practice (P = .01). Somatic anxiety intensity increased from pre-, to mid- to post-exercise (P = .001) irrespective of condition. This study suggests that badminton serve performance is negatively affected when physiological arousal, via badminton-specific exercise, and cognitive anxiety, via perceived competition, are high.

Magneto-Optics in the Service of Medicine - Diagnosis via the Cotton-Mouton Effect-

The Cotton-Mouton effect is presented and discussed as a means of detecting haemozoin and in the context of diagnosing malaria and schistosomiasis.

The influence of cycling intensity upon cognitive response during inferred practice and competition conditions

ABSTRACT In many sport and exercise situations, cognitive performance is required under conditions of high physiological load and high cognitive anxiety. However, few studies have assessed all these components in situ. The current study sought to address this issue. Fourteen adults (9 males, 5 females) completed 2 incremental exercise trials (perceived competition or perceived practice) in a counterbalanced order. Cognitive performance, via a test of visual discrimination, rating of perceived exertion (RPE), heart rate (HR), blood lactate (Bla), and anxiety scores, was recorded at rest, 70% and 90% . Visual discrimination response times were faster at rest compared to 70% (P = 0.001) and 90% (P = 0.002) and at 70% compared to 90% (P = 0.04) in the competitive condition. HR post-instructions (P = 0.0001), at 70% (P = 0.001) and 90% (P = 0.0001), was significantly higher in competition compared to practice. RPE was higher in the competitive condition compared to the practice condition (P = 0.023). Cognitive anxiety intensity was significantly higher in the competitive condition, at 70% and 90% (P = 0.001). This study suggests that cognitive performance is more negatively affected when physiological arousal and cognitive anxiety are at their highest. Coaches and athletes should be mindful of such effects and seek to develop skills to offset such responses or to structure training to better represent competition.

Nitration of lysozyme by ultrasonic waves; demonstration by immunochemistry and mass spectrometry

Solutions containing hen egg white lysozyme (HEWL) and nitrite were exposed to ultrasonic irradiation in order to study the possible sonochemical modifications. This is the first demonstration of the nitration of tyrosine residues in a protein (lysozyme) by the use of an ultrasonic field alone. Sonochemically nitrated lysozyme was detected using the immunochemical techniques dot blot immunodetection and enzyme-linked immunosorbent assay (ELISA). The sonically oxidised and nitrated protein solutions were analysed by Fourier transform ion cyclotron resonance (FT-ICR) mass spectrometry. Hydroxylated species were found in the absence of nitrite, whereas nitration was the major modification in the presence of nitrating agent, implying a competing mechanism between hydroxyl radicals and nitrite. Circular dichroism (CD) indicated that the ultrasonic experimental conditions chosen in this study had little effect on the tertiary and secondary structures of HEWL. Whilst enzymatic assay showed that the presence of nitrite provided a protective effect on the inactivation of the protein under ultrasonic irradiation, nevertheless partially purified, sonically nitrated lysozyme showed a dramatic decrease in lytic activity.

A laboratory-based introduction to seroepidemiology and its use in vaccination programme design

The development of vaccination programmes relies on an understanding of the epidemiology and transmission dynamics of the pathogen. Whilst these concepts could be delivered using the traditional lecture format, a practical workshop approach would encourage deeper understanding and appreciation. However, an authentic laboratory-based seroepidemiological study using human and pathogen material would be costly, logistically complicated and raise ethical issues. The workshop presented here uses a cheap and safe model of an infectious disease immuno assay alongside spreadsheet analysis as a tool for introducing aspects of infectious disease epidemiology, and some theoretical concepts used in mass immunisation programme design. It isdesigned to represent a typical directly-transmitted childhood viral infection (e.g. measles) within a community prior to mass immunisation. Results can be discussed through comparison with a hypothetical data set and interms of herd immunity, endemicity and the type of transmission as well as average age at infection, the basic reproduction number (Ro) and other parameters of importance to vaccination programme design.