Annually resolved North Atlantic marine climate over the last millennium.

Owing to the lack of absolutely dated oceanographic information before the modern instrumental period, there is currently significant debate as to the role played by North Atlantic Ocean dynamics in previous climate transitions (for example, Medieval Climate Anomaly-Little Ice Age, MCA-LIA). Here we present analyses of a millennial-length, annually resolved and absolutely dated marine δ18O archive. We interpret our record of oxygen isotope ratios from the shells of the long-lived marine bivalve Arctica islandica (δ18O-shell), from the North Icelandic shelf, in relation to seawater density variability and demonstrate that solar and volcanic forcing coupled with ocean circulation dynamics are key drivers of climate variability over the last millennium. During the pre-industrial period (AD 1000-1800) variability in the sub-polar North Atlantic leads changes in Northern Hemisphere surface air temperatures at multi-decadal timescales, indicating that North Atlantic Ocean dynamics played an active role in modulating the response of the atmosphere to solar and volcanic forcing.

Using body temperature, food and water consumption as biomarkers of disease progression in mice with Eµ-myc lymphoma.

BACKGROUND: Non-invasive biomarkers of disease progression in mice with cancer are lacking making it challenging to implement appropriate humane end points. We investigated whether body temperature, food and water consumption could be used to predict tumour burden. METHODS: Thirty-six male, wild-type C57Bl/6 mice were implanted with subcutaneous RFID temperature sensors and inoculated with Eµ-myc tumours that infiltrate lymphoid tissue. RESULTS: Decrease in body temperature over the course of the study positively predicted post-mortem lymph node tumour burden (R(2)=0.68, F(1,22)=44.8, P<0.001). At experimental and humane end points, all mice that had a mean decrease in body temperature of 0.7 °C or greater had lymph nodes heavier than 0.5 g (100% sensitivity), whereas a mean decrease in body temperature <0.7 °C always predicted lymph nodes lighter than 0.5 g (100% specificity). The mean decrease in food consumption in each cage also predicted mean post-mortem lymph node tumour burden at 3 weeks (R(2)=0.89, F(1,3)=23.2, P=0.017). CONCLUSION: Temperature, food and water consumption were useful biomarkers of disease progression in mice with lymphoma and could potentially be used more widely to monitor mice with other forms of cancer.

Superior proteome stability in the longest lived animal.

Bivalve mollusks have several unique traits, including some species with exceptionally long lives, others with very short lives, and the ability to determine the age of any individual from growth rings in the shell. Exceptionally long-lived species are seldom studied yet have the potential to be particularly informative with respect to senescence-resistance mechanisms. To this end, we employed a range of marine bivalve mollusk species, with lifespans ranging from under a decade to over 500 years, in a comparative study to investigate the hypothesis that long life requires superior proteome stability. This experimental system provides a unique opportunity to study closely related organisms with vastly disparate longevities, including the longest lived animal, Arctica islandica.Specifically, we investigated relative ability to protect protein structure and function, both basally and under various stressors in our range of species. We found a consistent relationship between species longevity, resistance to protein unfolding, and maintenance of endogenous enzyme (creatine kinase) activity. Remarkably, our longest-lived species, Arctica islandica (maximum longevity >500 years), had no increase in global proteome unfolding in response to several stressors. Additionally, the global proteome of shorter-lived species exhibited less resistance to temperature-induced protein aggregation than longer-lived species. A reporter assay, in which the same protein's aggregation properties was assessed in lysates from each study species, suggests that some endogenous feature in the cells of long-lived species, perhaps small molecular chaperones, was at least partially responsible for their enhanced proteome stability. This study reinforces the relationship between proteostasis and longevity through assessment of unfolding, function, and aggregation in species ranging in longevity from less than a decade to more than five centuries.

Assessment of trace elements in the shell layers and soft tissues of the pearl oyster Pinctada radiata using multivariate analyses: a potential proxy for temporal and spatial variations of trace elements.

Concentrations of trace elements (Cd, Cu, Ni, Pb, V, and Zn) were determined in the soft tissues (adductor muscle and gills) of the pearl oyster Pinctada radiata and surficial sediments from two sampling sites located in the northern part of the Persian Gulf by Graphite Furnace Atomic Absorption Spectrophotometer (GFAAS). Moreover, the levels of Li, Mg, Al, Mn, Fe, Cu, Sr, Ba, Pb, and Zn were measured in two shell layers (prismatic and nacreous) using Laser Ablation Inductively Coupled Plasma Mass Spectrometer (LA-ICP-MS). There were significant differences between the sampling sites with regard to mean concentrations of Cu, Mn, and Al in the prismatic layers of the shells. But in terms of the soft tissues, only in the case of Ni accumulation in the muscle significant differences between the sites could be observed. No significant differences could be found between the sites from the elements concentrations in the sediments point of view. The levels of Cd, Cu, Ni, and Zn in the gills were markedly higher than those in the muscle. Concentrations of Mn, Mg, Li, and Cu in the prismatic layer were significantly higher than in the nacreous but the reverse case could be found for Sr. The patterns of metal occurrence in the selected tissues, shell layers, and sediments exhibited the following descending order: Zn, Ni > Cd, Cu > V, and Pb and Zn, Ni, Cd > Cu, V, and Pb for muscle and gills, respectively; Zn > Cu, Ni, Pb, Cd, and V for sediments; Mg > Sr, Mn, Li, Al, Fe, Ba, Cu, Pb, and Zn for the prismatic layer; and Sr, Mg > Mn, Al, Fe, Li, Ba, Cu, Pb, and Zn for the nacreous layer. In most cases, the temporal variations of the elements levels in the prismatic layer were clearer than those in the nacreous layer (especially for Li, Mg, Mn, Pb, and Fe). Comparison of the gained data from this study with the other relevant researches shows that in most cases the levels of the elements in this investigation either fell within the range for other world areas or were lower. Generally, it can be concluded that the shell (especially prismatic layer) of P. radiata can be considered as a suitable proxy for temporal and spatial variations of the trace elements (and probably some environmental parameters) in the study area.

Maximum shell size, growth rate, and maturation age correlate with longevity in bivalve molluscs.

Bivalve molluscs are newly discovered models of successful aging, and this invertebrate group includes Arctica islandica, with the longest metazoan life span. Despite an increasing biogerontological focus on bivalves, their life history traits in relation to maximum age are not as comprehensively understood as those in vertebrate model aging organisms. We explore the allometric scaling of longevity and the relationship between development schedules (time to maturity and growth rate) and longevity in the Bivalvia. Using a traditional nonphylogenetic approach and the phylogenetically independent contrasts method, the relationship among these life history parameters is analyzed. It is demonstrated that in bivalves, maximum shell size, development, and growth rates all associate with longevity. Our findings support the observations of life history patterns in mammals and fish. This is the first investigation into the relationship among longevity, size, and development schedules throughout this group, and the results strengthened by the control for phylogenetic independence.

Identification of growth increments in the shell of the bivalve mollusc Arctica islandica using backscattered electron imaging.

Annually resolved growth increments in the shell of the bivalve mollusc Arctica islandica have previously been used in combination with geochemical measurements to successfully construct high-resolution proxy records of past marine environmental conditions. However, to ensure the accuracy of these paleoenvironmental reconstructions it is essential that the annual growth series of increments within the examined shells are reliably identified, and can be distinguished from spurious lines caused by nonannual perturbations such as those resulting from storm disturbance. The current methods used for identifying the growth increment series are sometimes compromised because of ambiguity that results from the employed preparation methods. Here it is shown that backscattered electron imaging of polished shell cross sections may be used to clearly discriminate between the two compositionally and structurally distinct increments that comprise 1 year of outer shell growth. This method, involving minimal specimen preparation, is likely to be primarily useful as a validation technique of particular value in cases where increment identification using existing methods is difficult or ambiguous.

Heavy metal concentrations in the soft tissues of swan mussel (Anodonta cygnea) and surficial sediments from Anzali wetland, Iran.

Concentrations of cadmium, copper, and lead were determined in surficial sediments and the soft tissues (foot and gills) of swan mussel Anodonta cygnea from two sampling sites in Anzali wetland, which is an internationally important wetland registered in the Ramsar Convention. The metal contents in the mussel species from the studied region were comparable to other world areas. In most cases, the levels of the metals either fell within the range for other areas or were lower. There were significant differences between the tissues for the accumulation of Cd and Pb. Only in the case of Pb accumulation in gills significant differences between the specimens from the selected sampling sites could be observed. Age-related correlations were found in the case of Cu accumulation in foot and Cd levels in gills. No weight-dependent trend could be observed for the accumulation of the three elements. There was significant negative width-dependent relationship in the case of Cu. A significant negative correlation was also found between the maximum shell height and Cu accumulation in the gills. The only association among the elements in the selected soft tissues was found between Cd and Pb. Highly significant differences could be found between the sampling sites from the concentration of the elements in sediments point of view. The pattern of metal occurrence in the selected tissues and sediments exhibited the following descending order: Pb, Cu>Cd for gills, Cu>Pb, Cd for foot, and Cu>Pb>Cd for sediments. The mean concentrations of Cd and Pb in the sediments from the study area were higher than the global baseline values and world average shale. In the case of Cu, our results were somewhat higher than the baseline values but well below the world average shale.

Reported analgesic administration to rabbits, pigs, sheep, dogs and non-human primates undergoing experimental surgical procedures.

Reported analgesic use following experimental surgery is low in rodents and there has been little published information on the frequency of analgesic use in other laboratory species. A structured literature review was conducted to examine analgesic administration in larger laboratory animals. The Scirus search engine was used to identify studies published in peer-reviewed journals that reported carrying out experimental surgery on 'large' laboratory animals, specifically rabbits, pigs, sheep, dogs and non-human primates. Seventy-four studies between 2000 and 2001 and 75 studies between 2005 and 2006 were included in the review. There was an increase in the reported administration of systemic analgesics to these species from 50% in 2000-2001 to 63% in 2005-2006. When all agents with analgesic properties were considered (systemic analgesics, local anaesthetics and anaesthetics with analgesic components), the proportion of papers that reported some form of analgesic administration to 'large' laboratory animals increased from 86% in 2000-2001 to 89% in 2005-2006. Overall rabbits, pigs, sheep, dogs and non-human primates were more likely to receive analgesics following potentially painful experimental procedures than has been reported in laboratory rodents but analgesic administration to 'large' laboratory species is still not optimal.

Reported analgesic and anaesthetic administration to rodents undergoing experimental surgical procedures.

A structured literature review was carried out to assess recent trends in the administration of analgesics and anaesthetics to laboratory rats and mice undergoing surgical procedures. The ScienceDirect database was used to systematically identify studies published in peer-reviewed journals over two periods (2000-2001 and 2005-2006), 86 studies from each time period were included in the review. The total number of animals that underwent surgery, species used, type of procedure, anaesthetic regimen and analgesic administration were noted for each study. There was an increase in the reported administration of systemic analgesics from 10% in 2000-2001 to 20% in 2005-2006. Buprenorphine was the most commonly reported analgesic in both periods (2000-2001: 78%, 2005-2006: 35%) and reporting the use of non-steroidal anti-inflammatory drugs increased from 11% to 53%. There was also a change in reported anaesthetic practices, notably a decrease in the use of pentobarbital and an increase in the use of isoflurane and ketamine/xylazine. Although reported administration of analgesics has increased and there has been some refinement in the selection of anaesthetic agents used, the findings of this review suggest that there is still significant scope for improvement with respect to the perioperative care of laboratory rodents.

Positive effects of exercise on falls and fracture risk in osteopenic women.

UNLABELLED: Exercise may affect osteopenic women at risk of falls and fractures. A workstation approach to exercise was evaluated in a randomised study of 98 women. The intervention group improved in measures of balance, strength and bone density. This study supports a preventative exercise approach that aims to reduce risk factors for fractures and falls, in women already at risk, through balance training and weight-bearing activity. INTRODUCTION: The objective of this study was to determine the effects of a workstation balance training and weight-bearing exercise program on balance, strength and bone mineral density (BMD) in osteopenic women. A single-blinded randomised controlled trial (RCT) was undertaken for 20 weeks with measurements at baseline and completion. MATERIALS AND METHODS: Ninety-eight (98) community-dwelling osteopenic women aged 41-78 years were recruited through the North Brisbane electoral roll. Subjects were randomised via computer-generated random numbers lists into either a control (receiving no intervention), or exercise group (two one-hour exercise sessions per week for 20 weeks with a trained physiotherapist). Assessments at baseline and post-intervention included balance testing (five measures), strength testing (quadriceps, hip adductors / abductors / external rotators and trunk extensors), and DXA scans (proximal femur and lumbar spine). Baseline assessment showed no significant differences between groups for all demographics and measures except for subjects taking osteoporosis medication. The percentage differences between pre- and post-intervention measurements were examined for group effect by ANOVA using an intention-to-treat protocol. RESULTS: Ninety-eight women (mean age 62.01 years, SD 8.9 years) enrolled in the study. The mean number of classes attended for the 42 participants in the exercise group who completed the program was 28.2 of a possible 40 classes (71%). At the completion of the trial the intervention group showed markedly significant better performances in balance (unilateral and bilateral stance sway measures, lateral reach, timed up and go and step test) (p < 0.05) with strong positive training effects reflecting improvements of between 10% to 71%. Similarly there were gains in strength of the hip muscles (abductors, adductors, and external rotators), quadriceps and trunk extensors with training effects between 9% and 23%. CONCLUSIONS: Specific workstation exercises can significantly improve balance and strength in osteopenic women. This type of training may also positively influence bone density although further study is required with intervention over a longer period. A preventative exercise program may reduce the risk of falls and fractures in osteopenic women already at risk.

Evaluation of the efficacy of a novel electronic pain assessment device, the Pain Gauge, for measuring postoperative pain in rats.

One of the major challenges for individuals working with laboratory animals is the recognition and alleviation of pain. The Pain Gauge is marketed as a pain assessment device that measures electrodermal activity. To establish whether the Pain Gauge is effective in assessing postoperative pain in laboratory rats, preoperative and postoperative pain gauge scores ('pain scores') were obtained from 67 rats. Rats were randomly assigned to one of three experimental groups (laparotomy, craniotomy or control) and to one of four analgesic groups (meloxicam [2 mg/kg s.c.] or parecoxib [1, 5 or 20 mg/kg i.v.]). Five consecutive 'pain scores' were obtained from each animal at each of five time points (preprocedure, and at 1, 2, 3 and 4 h postoperatively). Overall there was a significant difference between 'pain scores' at different time points; mainly a decrease at 1 h postoperatively compared with the preoperative scores. There was no overall increase in postoperative 'pain scores' in the rats that were most likely to suffer from postoperative pain (rats given a lower dose of analgesic that underwent a surgical procedure) compared with rats that did not undergo a potentially painful procedure (rats in anaesthesia-only/control group). Therefore it was concluded that the Pain Gauge is ineffective in assessing postoperative pain in rats in this study.

Quantification of the timing of continuous modulated muscle activity in a repetitive-movement task.

The timing of muscle activity is commonly measured in studies of motor control. In repetitive-movement tasks, muscle activity may be continuous, and no defined onset or offset of activity may be measured. This does not imply that no timing of muscle activity occurs. Where activity is continuous, this timing will typically be exhibited by modulation of the amplitude of the signal in specific movement phases. The existence of this electromyographic (EMG) timing is dependent upon the existence of EMG amplitude modulation. This paper investigates this relationship in developing a quantification algorithm of EMG timing in a repetitive-movement task. A frequency domain quantification algorithm involving EMG linear-envelope generation is used. An EMG simulation algorithm is used to test this algorithm and determine the minimal amplitude-modulation threshold for timing detection. At five repetitive-movement speeds (25, 50, 75, 100 and 125 cycles of movement per minute), thresholds between 1.558 and 2.326 times maximal to minimal linear-envelope amplitude are required for reliability of timing detection. Analysis of variance indicates that the robustness of the quantification algorithm was not significantly affected by burst width (F = 3.69, p = 0.055) or the underling input timing parameter (F = 0.52, p = 0.992). The phase-lead/lag quantification algorithm represents a useful tool for the analysis motor control via EMG during repetitive-movement tasks.

Lumbo-pelvic joint protection against antigravity forces: motor control and segmental stiffness assessed with magnetic resonance imaging.

The antigravity muscles of the lumbo-pelvic region, especially transversus abdominis (TrA), are important for the protection and support of the weightbearing joints. Measures of TrA function (the response to the postural cue of drawing in the abdominal wall) have been developed and quantified using magnetic resonance imaging (MRI). Cross-sections through the trunk allowed muscle contraction as well as the large fascial attachments of the TrA to be visualized. The cross sectional area (CSA) of the deep musculo-fascial system was measured at rest and in the contracted state, using static images as well as a cine sequence. In this developmental study, MRI measures were undertaken on a small sample of low back pain (LBP) and non LBP subjects. Results demonstrated that, in non LBP subjects, the draw in action produced a symmetrical deep musculo-fascial "corset" which encircles the abdomen. This study demonstrated a difference in this "corset" measure between subjects with and without LBP. These measures may also prove useful to quantify the effect of unloading in bedrest and microgravity exposure.

Investigation of hip abductor activation in subjects with clinical unilateral hip osteoarthritis.

OBJECTIVES: (a) To compare the magnitude of gluteus medius and tensor fascia lata activation between a group of subjects with clinical unilateral hip osteoarthritis and a group of healthy older adults. (b) To compare the magnitude of activation of the gluteus medius and tensor fascia lata between sides in a group of subjects with clinical unilateral hip osteoarthritis and a group of healthy older adults. METHODS: 19 subjects with clinical unilateral hip osteoarthritis and 19 healthy controls were investigated. The subjects performed a stepping task during which recordings were obtained using surface electromyograms from the hip abductors, and kinetic data were obtained from a dual force platform. RESULTS: Subjects with clinical hip osteoarthritis had higher gluteus medius activation than the healthy older adults (p=0.037). In addition, there were no differences in the magnitude of gluteus medius activation between the sides (p=0.733). There was no difference in the force platform data between the groups (p=0.078). CONCLUSIONS: The increased magnitude of gluteus medius activation in the group with hip osteoarthritis is evidence of a muscular dysfunction associated with hip disease. This has implications for the progressive nature of the disease and for its conservative management.

The health of the human skeletal system for weight bearing against gravity: The role of deloading the musculo-skeletal system in the development of musculoskeletal injury.

Musculo-skeletal disease is a major health problem which continues to increase in developed countries. A mechanism related hypothesis is presented to explain why most musculo-skeletal injury has an insidious onset and is not linked to a single traumatic event. The hypothesis predicts a close link between a dysfunction in the antigravity muscle system, which protects joints from injury, and the development of musculoskeletal disease patterns.

Clonidine-induced vasoconstriction in awake volunteers.

UNLABELLED: We evaluated the vasomotor effects of clonidine in awake subjects with an intact central cardiovascular regulatory system. To determine the lower limit of the vasoconstrictive effect of clonidine in awake volunteers, we blocked sympathetic innervation to the left arm by anesthetizing the brachial plexus. We then measured arterial blood pressure and vasoconstriction via finger volume plethysmography measuring infrared light transmitted through a fingertip (LTF). LTF values obtained from the left arm were compared with those from the neurally intact right arm during four progressively increasing IV doses of clonidine, targeting plasma clonidine concentrations of 0.3, 0.45, 0.68, and 1.0 ng/mL. Clonidine decreased systolic blood pressure (P < 0.004) from 135 +/- 8 mm Hg to 115 +/- 8 mm Hg and heart rate (P = 0.0017) from 68 +/- 7 mm Hg to 61 +/- 10 mm Hg. Clonidine decreased LTF by -12% +/- 11% (P < 0.0001) less than preinfusion values at the 0.68 ng/mL target concentration in the right hand. In contrast, in the left hand, clonidine increased LTF significantly more than (P < 0.0001) preinfusion values at all target concentrations, with a maximal increase of 30% +/- 7%. We conclude that IV clonidine, at doses that decrease arterial blood pressure, causes arterial vasoconstriction in awake subjects. IMPLICATIONS: IV clonidine, at doses that decrease blood pressure, causes arterial vasoconstriction in awake subjects. These data suggest that an alpha-2 agonist with a high alpha-2a/alpha-2b selectivity should provide more profound sedative and analgesic effects with less undesirable vasoconstrictive effects.

Long-term effects of specific stabilizing exercises for first-episode low back pain.

STUDY DESIGN: A randomized clinical trial with 1-year and 3-year telephone questionnaire follow-ups. OBJECTIVE: To report a specific exercise intervention's long-term effects on recurrence rates in acute, first-episode low back pain patients. SUMMARY OF BACKGROUND DATA: The pain and disability associated with an initial episode of acute low back pain (LBP) is known to resolve spontaneously in the short-term in the majority of cases. However, the recurrence rate is high, and recurrent disabling episodes remain one of the most costly problems in LBP. A deficit in the multifidus muscle has been identified in acute LBP patients, and does not resolve spontaneously on resolution of painful symptoms and resumption of normal activity. Any relation between this deficit and recurrence rate was investigated in the long-term. METHODS: Thirty-nine patients with acute, first-episode LBP were medically managed and randomly allocated to either a control group or specific exercise group. Medical management included advice and use of medications. Intervention consisted of exercises aimed at rehabilitating the multifidus in cocontraction with the transversus abdominis muscle. One year and three years after treatment, telephone questionnaires were conducted with patients. RESULTS: Questionnaire results revealed that patients from the specific exercise group experienced fewer recurrences of LBP than patients from the control group. One year after treatment, specific exercise group recurrence was 30%, and control group recurrence was 84% (P < 0.001). Two to three years after treatment, specific exercise group recurrence was 35%, and control group recurrence was 75% (P < 0.01). CONCLUSION: Long-term results suggest that specific exercise therapy in addition to medical management and resumption of normal activity may be more effective in reducing low back pain recurrences than medical management and normal activity alone.

Functional roles of abdominal and back muscles during isometric axial rotation of the trunk.

Electromyographic (EMG) studies have shown that a large number of trunk muscles are recruited during axial rotation. The functional roles of these trunk muscles in axial rotation are multiple and have not been well investigated. In addition, there is no information on the coupling torque at different exertion levels during axial rotation. The aim of the study was to investigate the functional roles of rectus abdominis, external oblique, internal oblique, latissimus dorsi, iliocostalis lumborum and multifidus during isometric right and left axial rotation at 100%, 70%, 50% and 30% maximum voluntary contractions (MVC) in a standing position. The coupling torques in sagittal and coronal planes were measured during axial rotation to examine the coupling nature of torque at different levels of exertions. Results showed that the coupled sagittal torque switches from nil to flexion at maximum exertion of axial rotation. Generally, higher EMG activities were shown at higher exertion levels for all the trunk muscles. Significant differences in activity between the right and left axial rotation exertions were demonstrated in external oblique, internal oblique, latissimus dorsi and iliocostalis lumborum while no difference was shown in rectus abdominis and multifidus. These results demonstrated the different functional roles of trunk muscles during axial rotation. This is important considering that the abdominal and back muscles not only produce torque but also maintain the spinal posture and stability during axial rotation exertions. The changing coupling torque direction in the sagittal plane when submaximal to maximal exertions were compared may indicate the complex nature of the kinetic coupling of trunk muscles.