Acid-base effects of a bicarbonate-balanced priming fluid during cardiopulmonary bypass: comparison with Plasma-Lyte 148. A randomised single-blinded study

Fluid-induced metabolic acidosis can be harmful and can complicate cardiopulmonary bypass. In an attempt to prevent this disturbance, we designed a bicarbonate-based crystalloid circuit prime balanced on physico-chemical principles with a strong ion difference of 24 mEq/l and compared its acid-base effects with those of Plasma-Lyte 148, a multiple electrolyte replacement solution containing acetate plus gluconate totalling 50 mEq/l. Twenty patients with normal acid-base status undergoing elective cardiac surgery were randomised 1:1 to a 2 litre prime of either bicarbonate-balanced fluid or Plasma-Lyte 148. With the trial fluid, metabolic acid-base status was normal following bypass initiation (standard base excess 0.1 (1.3) mEq/l, mean, SD), whereas Plasma-Lyte 148 produced a slight metabolic acidosis (standard base excess -2.2 (2.1) mEq/l). Estimated group difference after baseline adjustment was 3.6 mEq/l (95% confidence interval 2.1 to 5.1 mEq/l, P=0.0001). By late bypass, mean standard base excess in both groups was normal (0.8 (2.2) mEq/l vs. -0.8 (1.3) mEq/l, P=0.5). Strong ion gap values were unaltered with the trial fluid, but with Plasma-Lyte 148 increased significantly on bypass initiation (15.2 (2.5) mEq/l vs. 2.5 (1.5) mEq/l, P < 0.0001), remaining elevated in late bypass (8.4 (3.4) mEq/l vs. 5.8 (2.4) mEq/l, P < 0.05). We conclude that a bicarbonate-based crystalloid with a strong ion difference of 24 mEq/l is balanced for cardiopulmonary bypass in patients with normal acid-base status, whereas Plasma-Lyte 148 triggers a surge of unmeasured anions, persisting throughout bypass. These are likely to be gluconate and/or acetate. Whether surges of exogenous anions during bypass can be harmful requires further study.

A troponin T mutation that causes infantile restrictive cardiomyopathy increases Ca2+ sensitivity of force development and impairs the inhibitory properties of troponin

Restrictive cardiomyopathy (RCM) is a rare disorder characterized by impaired ventricular filling with decreased diastolic volume. We are reporting the functional effects of the first cardiac troponin T (CTnT) mutation linked to infantile RCM resulting from a de novo deletion mutation of glutamic acid 96. The mutation was introduced into adult and fetal isoforms of human cardiac TnT (HCTnT3-DeltaE96 and HCTnT1-DeltaE106, respectively) and studied with either cardiac troponin I (CTnI) or slow skeletal troponin I (SSTnI). Skinned cardiac fiber measurements showed a large leftward shift in the Ca(2+) sensitivity of force development with no differences in the maximal force. HCTnT1-DeltaE106 showed a significant increase in the activation of actomyosin ATPase with either CTnI or SSTnI, whereas HCTnT3-DeltaE96 was only able to increase the ATPase activity with CTnI. Both mutants showed an impaired ability to inhibit the ATPase activity. The capacity of the CTnI.CTnC and SSTnI.CTnC complexes to fully relax the fibers after TnT displacement was also compromised. Experiments performed using fetal troponin isoforms showed a less severe impact compared with the adult isoforms, which is consistent with the cardioprotective role of SSTnI and the rapid onset of RCM after birth following the isoform switch. These data indicate that troponin mutations related to RCM may have specific functional phenotypes, including large leftward shifts in the Ca(2+) sensitivity and impaired abilities to inhibit ATPase and to relax skinned fibers. All of this would account for and contribute to the severe diastolic dysfunction seen in RCM.

Heart rate responses to Taekwondo training in experienced practitioners

The purpose of this study was to evaluate the heart rate (HR) responses of specific Taekwondo training activities, practiced by experienced practitioners in a natural training environment. Eight male experienced Taekwondo practitioners, with 3- 13 years (5.4 +/- 3.2 years) experience took part in a 5-day Taekwondo training camp. Continuous HR measures were recorded at 5-second intervals during 6 training sessions; each session was observed and notated, and a diary of training activities was recorded. The HR responses were assimilated into 8 fundamental training activities for analysis: elastics, technical combinations, step sparring, pad work, forms, basic techniques and forms, sparring drills, and free sparring. Taekwondo training elicited HR into 64.7-81.4% of HR maximum (%HRmax). Moderate relative exercise intensities (64.7-69.4%HRmax) were elicited by elastics, technical combinations, and step sparring. The remaining 5 training activities elicited hard relative exercise intensities (74.7-81.4%HRmax). One-way repeated-measures analysis of variance with post hoc analysis revealed that elastics, technical combinations, and step sparring elicited significantly lower relative intensities than the remaining training activities (p < 0.05). Furthermore, forms, basic techniques and forms, sparring drills, and free sparring elicited significantly higher relative intensities than the remaining training activities (p < 0.05). In conclusion, all Taekwondo training activities in this study seemed suitable for cardiovascular conditioning, although different training activities stressed the cardiovascular system to different degrees. Practically, this suggests coaches need to structure Taekwondo training sessions based not only on the technical and tactical needs of practitioners but also in a manner that enables sufficient cardiovascular conditioning for competition.

Effect of an acute necrotic bacterial gill infection and feed deprivation on the metabolic rate of Atlantic salmon Salmo salar

In this study, experiments were conducted to examine the effect of an acute necrotic bacterial gill infection on the metabolic rate (M(O2)) of Atlantic salmon Salmo salar. Fed and unfed Atlantic salmon smolts were exposed to a high concentration (5 x 10(12) CFU ml(-1)) of the bacteria Tenacibaculum maritimum, their routine and maximum metabolic rates (M(O2rout) and M(O2max), respectively) were measured, and relative metabolic scope determined. A significant decrease in metabolic scope was found for both fed and unfed infected groups. Fed infected fish had a mean +/- standard error of the mean (SEM) decrease of 2.21 +/- 0.97 microM O2 g(-1) h(-1), whilst unfed fish a mean +/- SEM decrease of 3.16 +/- 1.29 microM O2 g(-1) h(-1). The decrease in metabolic scope was a result of significantly increased M(O2rout) of both fed and unfed infected salmon. Fed infected fish had a mean +/- SEM increase in M(O2rout) of 1.86 +/- 0.66 microM O2 g(-1) h(-1), whilst unfed infected fish had a mean +/- SEM increase of 2.16 +/- 0.72 microM O2 g(-1) h(-1). Interestingly, all groups maintained M(O2max) regardless of infection status. Increases in M(O2rout) corresponded to a significant increase in blood plasma osmolality. A decrease in metabolic scope has implications for how individuals allocate energy; fish with smaller metabolic scope will have less energy to allocate to functions such as growth, reproduction and immune response, which may adversely affect the efficiency of fish growth.

Recurrent non-specific low-back pain in adolescents: the role of exercise

This study evaluated the efficacy of an exercise programme as an intervention for recurrent non-specific low-back pain (NLSBP) in adolescents. A randomized controlled trial was conducted with an experimental group (n = 27, age 14.6 years) who participated in an 8-week exercise programme and a matched control group (n = 27, age 14.6 years) who continued normal daily activities. All participants suffered from recurrent NSLBP. Pre and post intervention measures of NSLBP status (pain severity and consequences) and daily inactivity (time spent sitting, PC time, TV time) were reported in one week diaries. Two-way mixed ANOVA (independent variables: pre/post and experimental/control) was conducted for each dependent variable, significance was set at P < 0.05. Significant interaction effects were identified for the severity of pain, number of occasions missing sport due to NSLBP and amount of sport participated in. In each case the experimental group benefited from the exercise programme. In contrast, no significant interaction effects were observed for physical inactivity, both groups spent a similar amount of time sitting, watching TV and using a PC pre- and post- intervention. It was concluded that an exercise programme acted as an effective short-term treatment strategy for NSLBP in adolescents. Further evaluation is required to assess the long-term effectiveness.

Evidence that a novel thioesterase is responsible for polyketide chain release during biosynthesis of the polyether ionophore monensin

Polyether ionophores, such as monensin A, are known to be biosynthesised, like many other antibiotic polyketides, on giant modular polyketide synthases (PKSs), but the intermediates and enzymes involved in the subsequent steps of oxidative cyclisation remain undefined. In particular there has been no agreement on the mechanism and timing of the final polyketide chain release. We now report evidence that MonCII from the monensin biosynthetic gene cluster in Streptomyces cinnamonensis, which was previously thought to be an epoxide hydrolase, is a novel thioesterase that belongs to the alpha/beta-hydrolase structural family and might catalyse this step. Purified recombinant MonCII was found to hydrolyse several thioester substrates, including an N-acetylcysteamine thioester derivative of monensin A. Further, incubation with a hallmark inhibitor of such enzymes, phenylmethanesulfonyl fluoride, led to inhibition of the thioesterase activity and to the accumulation of an acylated form of MonCII. These findings require a reassessment of the role of other enzymes implicated in the late stages of polyether ionophore biosynthesis.

The effect of caffeine ingestion on 8 km run performance in a field setting

The aim of this study was to assess the effect of caffeine ingestion on 8 km run performance using an ecologically valid test protocol. A randomized double-blind crossover study was conducted involving eight male distance runners. The participants ran an 8 km race 1 h after ingesting a placebo capsule, a caffeine capsule (3 mg x kg(-1) body mass) or no supplement. Heart rate was recorded at 5 s intervals throughout the race. Blood lactate concentration and ratings of perceived exertion were recorded after exercise. A repeated-measures analysis of variance (ANOVA) identified a significant treatment effect for 8 km performance time (P < 0.05); caffeine resulted in a mean improvement of 23.8 s (95% confidence interval [CI] = 13.1 to 34.5 s) in 8 km performance time (1.2% improvement, 95% CI = 0.7 to 1.8%). In addition, a two-way (time x condition) repeated-measures ANOVA identified a significantly higher blood lactate concentration 3 min after exercise during the caffeine trial (P < 0.05). We conclude that ingestion of 3 mg . kg(-1) body mass of caffeine can improve absolute 8 km run performance in an ecologically valid race setting.

Removal of catheter at midnight versus early morning: the patients' perspective

BACKGROUND

With an increasing role of the patient as a partner in making a combined decision in care plan goals, it is important to identify the patient's perspective of the experience of removal of catheter (ROC).

METHODS

A non-consecutive prospective randomized study was performed in 84 patients who underwent a transurethral resection of the prostate to determine the impact of midnight versus early-morning ROC on sleep deprivation, over all discomfort to the patient.

RESULTS

There was no difference in the patient experience in both groups. We found a reduced frequency during the first 6 h of ROC at midnight. However, there was an increased incidence of sleep disturbances in this group. This may in part be due to an anxiety of urge incontinence and may be allayed by appropriate counselling. There was no delay in discharge of the patients in both groups.

CONCLUSION

The patients must, therefore, be given the choice of ROC either at midnight or early morning, as the advantages of a reduced frequency must be correlated with an increased incidence of sleep disturbances.

Histological evidence for the role of mechanical stress in modulating thermal denaturation of collagen

The hyperthermia and thermal denaturation literatures reveal a time-temperature equivalency when heating cells or connective tissues: thermal damage increases with increasing temperature (for the same duration) and increases with increasing duration (for the same temperature). Recent findings conversely suggest that increasing the mechanical loading on a tissue during heating decreases the thermal damage (for a given temperature and duration of heating). Surprisingly, however, there are few histological correlates of such damage. In this paper, we show that progressive light microscopic changes - swelling of collagen bands, thickening of collagen-rich layers, hyalinization, and loss of birefringence approximately - correlate very well with both increased heating times and decreased mechanical loading. Increased mechanical stress is thus thermally protective and should be considered in the design of clinical procedures that use heating to treat diseases or injuries.

Campylobacter jejuni gene expression in the chick cecum: evidence for adaptation to a low-oxygen environment

Transcriptional profiling of Campylobacter jejuni during colonization of the chick cecum identified 59 genes that were differentially expressed in vivo compared with the genes in vitro. The data suggest that C. jejuni regulates electron transport and central metabolic pathways to alter its physiological state during establishment in the chick cecum.

Identification of 4-amino-4-deoxychorismate synthase as the molecular target for the antimicrobial action of (6s)-6-fluoroshikimate

(6S)-6-Fluoroshikimate has antimicrobial activity. The molecular basis of this effect had not been identified, but there was speculation that (6S)-6-fluoroshikimate is first converted in vivo into 2-fluorochorismate, which then could inhibit 4-amino-4-deoxychorismate synthase (ADCS). 2-Fluorochorismate was prepared from E-fluorophosphoenolpyruvate and erythose-4-phosphate by the sequential reactions of DAHP synthase, dehydroquinate synthase, dehydroquinase, shikimate dehydrogenase, EPSP synthase, and chorismate synthase. Inhibition studies on ADCS showed that it was inhibited rapidly and irreversibly by 2-fluorochorismate. Electrospray mass spectrometry of the inactivated enzyme showed an additional mass of 198 +/- 10 Da. A novel peptide of 1087.6 Da was identified in the HPLC trace for the tryptic digest of 2-fluorochorismate-inactivated ADCS. Sequencing of this peptide by MS/MS showed that the peptide corresponded to residues 272-279 with a modification of 206.1 Da on Lys-274. This observation is particularly exciting in the context of a recent proposal for the catalytic mechanism of ADCS.

A school-based survey of recurrent non-specific low-back pain prevalence and consequences in children

The aim of this investigation was to provide evidence of the prevalence and consequences of recurrent low-back pain in children from Northwest England. A cross-sectional survey was conducted involving a standardized questionnaire with established reliability and validity. A cross-sectional sample of 500 boys (n = 249) and girls (n = 251) aged between 10 and 16 years participated in the study. Average lifetime prevalence of low-back pain was 40.2% [95% confidence interval (CI) = 38.7-41.6]. Most cases of low-back pain were acute episodes that did not lead to disabling consequences. In contrast, 13.1% (95% CI = 12.5-13.7) experienced recurrent low-back pain that led to disabling consequences; 23.1% visited a medical practitioner, 30.8% experienced loss of physical activity/sports and 26.2% had been absent from school because of low-back pain. Recurrent low-back pain was particularly evident during late adolescence where one in five children were cases. The health education implications of low-back pain in children are discussed. It was concluded that low-back pain is a common complaint during childhood, although most cases are acute episodes that represent little health consequence. In contrast, some children experience recurrent low-back pain that can lead to disabling consequences. Future research should focus on recurrent low-back pain cases since they often led to disabling consequences.

AVM modelling by multi-branching tube flow: large flow rates and dual solutions

Cerebral arteriovenous malformations (AVMs) present a common yet complex clinical challenge, through 'steal' phenomena, haemorrhage risks and epilepsy effects, aspects which are little understood even for individual lesions. The main difficulty lies in understanding the detailed haemodynamics of AVMs and especially the enhanced through-flow associated with steal. Mathematically, as a basic step, the paper investigates a nonlinear inviscid model for the planar incompressible flow of fluid through a branched geometry consisting of a single feeding mother tube which splits into two or more non-aligned daughter tubes. Recurrence relations between the unknown flow profiles in the daughter tubes and the incoming rotational flow profile in the mother tube are derived, analysed, and solved in detail in order to find the total flow rate. The results show greatly enhanced through-flow arising, for a fixed value of the total downstream flow area, either from non-unique solutions to the problem or more particularly from an increase in the number of daughter tubes, or from both, depending on the distribution of pressure differences applied across the branching region and the total downstream flow area. Extensions of the basic flow model are noted, along with comparisons with recent direct numerical simulations and discussion of possible repercussions in the context of treatment and clinical observations of enhanced through-flows in AVMs.

Specific evaluation of the function of force couples relevant for stabilization of the glenohumeral joint

Two clinical evaluation procedures for assessment of dynamic stability of the glenohumeral joint are presented in this paper, together with the biomedical evidence on which they are based. They are the Dynamic Rotary Stability Test (DRST) and the Dynamic Relocation Test (DRT). The purpose of the tests is presented and the technique required to perform the tests are described in detail.

Dynamic evaluation and early management of altered motor control around the shoulder complex

Altered dynamic control appears to be a significant contributing factor to shoulder dysfunction. The shoulder relies primarily on the rotator cuff for dynamic stability through mid-range. Hence, any impairment in the dynamic stabilizing system is likely to have profound effects on the shoulder complex. The rotator cuff appears to function as a deep stabilizer, similar to the transversus abdominus and vastus medialis obliquus, with some evidence of disruption to its stabilizing function in the presence of pain. Similarly, serratus anterior appears to function as a dynamic stabilizer, also demonstrating altered function in painful shoulders. Examination of dynamic control begins with a detailed examination of posture, evaluation of natural movement patterns and functional movements and assessment of the specific force couples relevant to shoulder function. One useful strategy in management of altered motor control related to these force couples is that of training isolated contraction of the rotator cuff prior to introduction of loaded activity, together with facilitation and training of appropriate scapular muscle force couples--serratus anterior and trapezius, in relation to arm elevation.

Analysis of the biosynthetic gene cluster for the polyether antibiotic monensin in Streptomyces cinnamonensis and evidence for the role of monB and monC genes in oxidative cyclization

The analysis of a candidate biosynthetic gene cluster (97 kbp) for the polyether ionophore monensin from Streptomyces cinnamonensis has revealed a modular polyketide synthase composed of eight separate multienzyme subunits housing a total of 12 extension modules, and flanked by numerous other genes for which a plausible function in monensin biosynthesis can be ascribed. Deletion of essentially all these clustered genes specifically abolished monensin production, while overexpression in S. cinnamonensis of the putative pathway-specific regulatory gene monR led to a fivefold increase in monensin production. Experimental support is presented for a recently-proposed mechanism, for oxidative cyclization of a linear polyketide intermediate, involving four enzymes, the products of monBI, monBII, monCI and monCII. In frame deletion of either of the individual genes monCII (encoding a putative cyclase) or monBII (encoding a putative novel isomerase) specifically abolished monensin production. Also, heterologous expression of monCI, encoding a flavin-linked epoxidase, in S. coelicolor was shown to significantly increase the ability of S. coelicolor to epoxidize linalool, a model substrate for the presumed linear polyketide intermediate in monensin biosynthesis.

Contribution of proton-translocating proteins to the virulence of Salmonella enterica serovars Typhimurium, Gallinarum, and Dublin in chickens and mice

We investigated the attenuating effects of a range of respiratory chain mutations in three Salmonella serovars which might be used in the development of live vaccines. We tested mutations in nuoG, cydA, cyoA, atpB, and atpH in three serovars of Salmonella enterica: Typhimurium, Dublin, and Gallinarum. All three serovars were assessed for attenuation in their relevant virulence assays of typhoid-like infections. Serovar Typhimurium was assessed in 1-day-old chickens and the mouse. Serovar Gallinarum 9 was assessed in 3-week-old chickens, and serovar Dublin was assessed in 6-week-old mice. Our data show variation in attenuation for the nuoG, cydA, and cyoA mutations within the different serovar-host combinations. However, mutations in atpB and atpH were highly attenuating for all three serovars in the various virulence assays. Further investigation of the mutations in the atp operon showed that the bacteria were less invasive in vivo, showing reduced in vitro survival within phagocytic cells and reduced acid tolerance. We present data showing that this reduced acid tolerance is due to an inability to adapt to conditions rather than a general sensitivity to reduced pH. The data support the targeting of respiratory components for the production of live vaccines and suggest that mutations in the atp operon provide suitable candidates for broad-spectrum attenuation of a range of Salmonella serovars.

Measurement error associated with spinal mobility measures in children with and without low-back pain

AIM

Evidence of the reliability of measurements in children is scarce, particularly in children with low-back pain. The aim of this investigation was to evaluate the measurement error associated with repeated measures of spinal mobility measures in children with and without low-back pain by establishing 95% limits of agreement.

METHODS

A repeated measures study was performed involving 119 children aged 11-16 y. Of this sample 30 subjects reported recurrent low-back pain and were classified as symptomatic, the remaining 89 subjects were asymptomatic. Standardized measures were taken, including the sit-and-reach test, hip range of motion (Leighton flexometer), lumbar flexibility (modified Schöber test) and lateral flexion of the spine. The same experimenter performed all testing, with 1 wk between the repeated measures.

RESULTS

Correlation coefficients suggested that all measures exhibited good reliability in both the symptomatic (r = 0.80-0.95) and asymptomatic groups (r = 0.88-0.99). In contrast, the limits of agreement showed that all measures exhibited random error. The magnitude of random error was typically greater in the symptomatic subjects, suggesting that low-back pain may influence the reliability of typical measures used in this population.

CONCLUSION

The magnitude of error must be interpreted in relation to analytical goals and the expected magnitude of change. In the authors' opinion the error presented appears acceptable for the serial monitoring of patients, although this will depend on the differences in mobility typically found.

An overview of the biology of the wharf borer beetle (Nacerdes melanura L., Oedemeridae) a pest of wood in marine structures

The UK distribution of N. melanura is reported, based on records from museum collections, government laboratories and a field survey of wooden marine structures and driftwood along the English and Welsh coastlines. The global distribution is also reported, based on a questionnaire survey. The life cycle of the wharf borer under different environmental conditions is described and the environmental conditions over the adult emergence period presented. The cellulase complex, xylanase and a range of dissacharases were present in the larval digestive tract when tunnelling archaeological oak.

Comparison of two assay methods for activities of uroporphyrinogen decarboxylase and coproporphyrinogen oxidase

Uroporphyrinogen decarboxylase (UROD) and coproporphyrinogen oxidase (copro'gen oxidase) are two of the least well understood enzymes in the heme biosynthetic pathway. In the fifth step of the pathway, UROD converts uroporphyrinogen III to coproporphyrinogen III by the decarboxylation of the four acetic acid side chains. Copro'gen oxidase then converts coproporphyrinogen III to protoporphyrinogen IX via two sequential oxidative decarboxylations. Studies of these two enzymes are important to increase our understanding of their mechanisms. Assay comparisons of UROD and copro'gen oxidase from chicken blood hemolysates (CBH), using a newly developed micro-assay, showed that the specific activity of both enzymes is increased in the micro-assay relative to the large-scale assay. The micro-assay has distinct advantages in terms of cost, labor intensity, amount of enzyme required, and sensitivity.

Juvenile hyperthyroidism in a cat

An 8-month-old, male domestic shorthaired cat presented for chronic weight loss, intermittent dyspnea, chronic diarrhea, hyperactivity, and weakness. The cat had a palpable thyroid nodule and increased serum total thyroxine and 3,5,3' triiodothyronine levels. The cat was diagnosed with hyperthyroidism, and a unilateral thyroidectomy was performed followed by radioactive iodine at a later date. The clinical signs resolved following radioactive iodine, and the cat subsequently developed clinical hypothyroidism.

Kinetic studies of novel di- and tri-propionate substrates for the chicken red blood cell enzyme coproporphyrinogen oxidase

Coproporphyrinogen oxidase is an important enzyme in heme biosynthesis and catalyses the sequential oxidative decarboxylation of propionates on the A and B rings of the porphyrinogen ring. The effects of substituents on the C and D rings have not been systematically evaluated for their effects on the kinetic constants, K(m) and V(max). A series of synthetic porphyrinogens have been tested for their ability to affect these kinetic constants for the chicken enzyme. The enzyme exhibited the largest V(max) when incubated with the authentic substrate and was clearly able to distinguish between various substituents on the C and D rings of the macrocycle. When co-incubated with substrate, the authentic product, protoporphyrinogen-IX, appears to inhibit coproporphyrinogen oxidase and this may have an important role in the regulation of this enzyme. Thus the model for the active site of this enzyme should be modified to take these factors into account.

Engineering of complex polyketide biosynthesis--insights from sequencing of the monensin biosynthetic gene cluster

The biosynthesis of complex reduced polyketides is catalysed in actinomycetes by large multifunctional enzymes, the modular Type I polyketide synthases (PKSs). Most of our current knowledge of such systems stems from the study of a restricted number of macrolide-synthesising enzymes. The sequencing of the genes for the biosynthesis of monensin A, a typical polyether ionophore polyketide, provided the first genetic evidence for the mechanism of oxidative cyclisation through which polyethers such as monensin are formed from the uncyclised products of the PKS. Two intriguing genes associated with the monensin PKS cluster code for proteins, which show strong homology with enzymes that trigger double bond migrations in steroid biosynthesis by generation of an extended enolate of an unsaturated ketone residue. A similar mechanism operating at the stage of an enoyl ester intermediate during chain extension on a PKS could allow isomerisation of an E double bond to the Z isomer. This process, together with epoxidations and cyclisations, form the basis of a revised proposal for monensin formation. The monensin PKS has also provided fresh insight into general features of catalysis by modular PKSs, in particular into the mechanism of chain initiation.