Multiplicity distribution and spectra of negatively charged hadrons in Au+Au collisions at square root of (sNN) = 130 GeV

The minimum-bias multiplicity distribution and the transverse momentum and pseudorapidity distributions for central collisions have been measured for negative hadrons ( h(-)) in Au+Au interactions at square root of ([s(NN)]) = 130 GeV. The multiplicity density at midrapidity for the 5% most central interactions is dN(h(-))/d(eta)/(eta = 0) = 280+/-1(stat)+/-20(syst), an increase per participant of 38% relative to pp collisions at the same energy. The mean transverse momentum is 0.508+/-0.012 GeV/c and is larger than in central Pb+Pb collisions at lower energies. The scaling of the h(-) yield per participant is a strong function of p( perpendicular). The pseudorapidity distribution is almost constant within /eta/<1.

Pion Interferometry of square root of (s(NN)) =130 GeV Au + Au collisions at RHIC

Two-pion correlation functions in Au+Au collisions at square root of [s(NN)] = 130 GeV have been measured by the STAR (solenoidal tracker at RHIC) detector. The source size extracted by fitting the correlations grows with event multiplicity and decreases with transverse momentum. Anomalously large sizes or emission durations, which have been suggested as signals of quark-gluon plasma formation and rehadronization, are not observed. The Hanbury Brown-Twiss parameters display a weak energy dependence over a broad range in square root of [s(NN)].

Event-by-event fluctuations of the Kaon-to-Pion ratio in central Pb+Pb collisions at 158 GeV per nucleon

We present the first measurement of fluctuations from event to event in the production of strange particles in collisions of heavy nuclei. The ratio of charged kaons to charged pions is determined for individual central Pb+Pb collisions. After accounting for the fluctuations due to detector resolution and finite number statistics we derive an upper limit on genuine nonstatistical fluctuations, which could be related to a first- or second-order QCD phase transition. Such fluctuations are shown to be very small.

The carriage of pro-inflammatory cytokine gene polymorphisms in recurrent pregnancy loss

PROBLEM

Recurrent pregnancy loss (RPL) affects 2-4% of couples, and remains largely unexplained. Recent studies have examined the role of cytokines in the maintenance of normal pregnancy, which is linked with an increased expression of Th2 cytokines. Overexpression of Th1 cytokines is associated with RPL. Knowing that functional polymorphisms exist for certain cytokines, it has therefore been suggested that women with RPL may have a genetic predisposition to overexpress Th1 cytokines.

METHOD OF STUDY

The genes for interleukin-1 beta (IL-1beta) and tumor necrosis factor alpha (TNF-alpha) carry functional gene polymorphisms. In both cases these are biallelic polymorphisms that can be detected by polymerase chain reaction followed by restriction fragment length polymorphism. The aim of this pilot study was to assess whether carriage of the rarer alleles (TNF*2 and IL-1B*2) could act as independent risk factors in recurrent miscarriage.

RESULTS

We found an increased incidence in the carriage of TNF*2, more pronounced in those women with two or more miscarriages. Carriage of the IL-1B*2 either alone or in association with TNF*2 was not associated with recurrent miscarriage.

CONCLUSION

There may be a role for these cytokine gene polymorphisms in RPL.

Cementing the wall: cell wall polysaccharide synthesising enzymes

The year under review has seen the first molecular characterisation, with proof of functionality, of Golgi membrane-bound glycosyltransferase enzymes catalysing the synthesis of non-cellulosic plant cell-wall polysaccharides.

Laxity of knee cruciate ligaments during pregnancy

Pregnancy-related increase in ligament laxity may cause joint instability. The purpose of this study was two-fold: 1) to assess knee laxity changes during pregnancy and 2) to evaluate the effect of exercise on knee laxity due to a typical prenatal fitness program. The subjects were healthy pregnant women. One group (N = 27) participated in exercise classes designed according to national guidelines. The second group (N = 38) was more sedentary. A clinical arthrometer, KT-1000, was used, and anterior and posterior drawer tests were performed. The results were added and averaged for the two knees. Laxity was constant in the second half of pregnancy and had significantly decreased by 14% 4 months after birth. No influence of parity or exercise was detected. The exercise program employing minimal to moderate weight bearing did not result in any measurable increases in knee laxity and, therefore, appears to be appropriate with regard to knee stability. These results should not, however, be extended to different types of exercise programs without additional research.

Desktop teleradiology in support of rural orthopedic trauma care

Research has shown that diagnostic quality images for most teleradiology applications requires a sophisticated telemedicine system and access to a large amount of bandwidth. While the ideal standards have been set by those involved in evaluating teleradiology, these standards are impractical for many small rural health centers which deliver routine trauma care. While there is no disagreement about the ultimate need for this level of teleradiology support, the purpose of this research was to determine whether Orthopedists would be able to read plain radiographs of orthopedic trauma injuries using a desktop teleradiology system in support of rural trauma care.

METHOD

Two radiology residents and two orthopedic residents viewed forty radiographs, twenty through a desktop teleradiology system and twenty in person. Diagnostic findings and certainty of diagnosis were recorded.

FINDINGS

There was no statistically significant difference between modalities in orthopedic residents' ability to correctly diagnose orthopedic trauma injuries. Further, for those instances when the diagnosis was imprecise, the residents were aware of their inability to make an accurate diagnosis.

CONCLUSION

Although the study was relatively limited and further research needs to be done, the use of desktop teleradiology in support of rural orthopedic trauma consultation is a promising alternative to the more expensive forms of telemedicine technology.

Trunk muscle parameters determined from MRI for lean to obese males

Transverse magnetic resonance images at the L(4)-L(5) level of 26 males ranging in body mass index from 19.7 to 39.5 were digitized using a computer video monitor with mouse-mediated digitization software. The digitized musculature included the right and left psoas, rectus, abdominis, quadratus lumborum, oblique, and paraspinal muscle groups. From the digitized profiles, cross-sectional areas, and anteroposterior and mediolateral moments from the vertebral centroid were subsequently calculated. Multiple regression formulae were derived to predict the muscle parameters from the most strongly related anthropometrics. Cross-sectional area and moment arms for lean and obese groups were also compared. Significant regression formulae were derived for the cross-sectional area of the rectus abdominis and obliques, for mediolateral moment arms of the paraspinals, psoas, and obliques, and for anteroposterior moments of all four muscles. Comparison of muscle parameters for lean and obese subjects revealed minimal differences, though normalization of muscle cross-sectional areas by trunk area produced values which were statistically smaller for all muscles of the obese relative to lean subjects. RELEVANCE:--Identifying variations in trunk muscular geometry across specific population groups will assist in further refining the existing morphometric data base used to estimate the forces experienced about the lower back. By identifying these variations, it may be possible to observe factors which may predispose a specific population to low back pain.

Segmental inertial parameters of the human trunk as determined from computed tomography

This study used computed tomography (CT) imaging to determine in vivo mass, center of mass (CM), and moments of inertia (Icm) about the CM of discrete segments of the human torso. Four subjects, two males and two females, underwent serial transverse CT scans that were collected at 1-cm intervals for the full length of the trunk. The pixel intensity values of transverse images were correlated to tissue densities, thereby allowing trunk section mass properties to be calculated. The percentage of body mass observed by vertebral levels ranged from 1.1% at T1 to 2.6% at L5. The masses of the upper, middle, and lower trunk segments as percentages of body mass were estimated to be 18.5, 12.2, and 10.7%, respectively. The whole trunk mass was estimated to comprise 41.6% of the total body mass. Transverse vertebral CM values were found to lie anterior to their respective vertebral centroids by up to 5.0 cm in the lower thoracic region. For the upper, middle, and lower trunk segments, the average CM positions were found to be 25.9, 62.5, and 86.9% of the distance from the superior to inferior ends of the trunk. The upper and middle trunk CMs corresponded to approximately 4.0 cm anterior to T7/T8 vertebral centroid levels and 1.0 cm anterior to L3/L4 vertebral centroid levels, respectively. For the whole trunk, the CM was 52.7% of the distance from the xiphoid process and approximately 2.0 cm anterior to L1/L2 vertebral centroid levels. Variations in CM and Icm values were observed between subject, but these were within the range of previous reports of body segment parameters. Differences from previous studies were attributable to variations in boundary definitions, measurement techniques, population groups, and body states (live versus cadaver) examined. The disparity between previous findings and findings of this study emphasizes the need to better define the segmental properties of the trunk so that improved biomechanical representation of the body can be achieved.

Exercise, posture, and back pain during pregnancy

In this article the effect of exercise on pregnancy-related back pain is reported. Sixty five pregnant volunteers were included in the study, of whom 27 were enrolled in exercise classes designed according to Canadian guidelines, and 38 acted as sedentary controls. Back pain and functional limitations were assessed every 4 weeks during pregnancy and 4 months postpartum by questionnaires. No significant differences in back pain or functional limitations reported by the two groups were found. The biomechanical factors measured in this study, weight, back posture, and laxity, were unable to explain most of the variation in pain reported. RELEVANCE: This study showed that fitness classes for pregnant women designed according to Canadian guidelines had no detectable effect on back pain during pregnancy. If prevention of pregnancy-related back pain is sought through exercise, design of fitness programmes for pregnant women should be reconsidered.

Exercise, posture, and back pain during pregnancy

One of the expected benefits of exercise programmes for pregnant women is to reduce or prevent back pain by improving posture. The aim of this project was to evaluate the effect of fitness classes for pregnant women on posture and back pain. In this article, postural aspects are reported. Sixty five pregnant volunteers were included in the study, of whom 27 were enrolled in exercise classes designed according to Canadian guidelines and 38 acted as sedentary controls. Posture was assessed every 4 weeks during pregnancy and 4 months postpartum by measuring curvatures of the lumbar and thoracic spines in a standard relaxed standing position from lateral photographs. Laxity of knee ligaments was also monitored using a clinical arthrometer. Weight gain could explain part of lordosis increase during pregnancy but the effect was not very strong. No effect of exercise on posture was detected. RELEVANCE: This study showed that fitness classes for pregnant women designed according to Canadian guidelines had no detectable effect on posture during pregnancy.

Inertial properties of the human trunk of males determined from magnetic resonance imaging

The purpose of this study was to evaluate the segmental parameters of the human trunk of males in vivo using magnetic resonance imaging (MRI). In addition, the efficacy of volumetric estimation and existing prediction formulas to produce segmental properties similar to those produced by MRI was evaluated. As opposed to finding one representative normal value for these parameters, a range of normal values was defined. For instance, the average trunk mass was 42.2% +/- 3.5% (x +/- SD) of body mass, but values ranged from 35.8% to 48.0%. To account for segment parameters more accurately, specific anthropometric measures need to be considered in addition to overall measures of body height and mass. These specific measures included segment length, circumference, width, and depth. Studies reporting general percentages based on height and/or mass were found to be inadequate predictors of segmental parameters of the trunk compared with MRI estimates. Volume-based estimates, which assume a uniform density distribution within a segment, were found to correspond closely to MRI values except for the thorax. However, the use of density values reflective of the living in vivo state would likely alleviate this disparity, thus indicating that the volumetric technique may be effective for deriving segmental parameters for large segments of the trunk. Future research should adopt noninvasive techniques such as MRI and/or volumetric estimation to enhance the predictability of segmental parameters of the body for specific population groups characterized by gender, developmental age, body type, and fitness level. Further efforts should be made to establish standardized boundary definitions for trunk segments to avoid unnecessary confusion, from which substantial errors may be introduced into biomechanical linked-segment analyses of human movement.

Detection of HCV-RNA in the blood donor population of Yorkshire

The purpose of this study was to develop a reliable and specific polymerase chain reaction (PCR) for the detection of hepatitis C virus-ribonucleic acid (HCV-RNA) in the plasma of blood donors who attend the Yorkshire Regional Transfusion Centre. These donors had previously had a positive or indeterminate recombinant immunoblot assay (RIBA) result. For increased sensitivity of reaction and greater specificity of product, a 'nested-primer' PCR was used. One hundred and ninety-two samples were examined, of which 18 were RIBA-positive and HCV-RNA was detected in 15 (83%) of them. Of the 174 RIBA indeterminates only one (0.6%) had detectable HCV-RNA. The rate of HCV-RNA detection in fresh and archive samples was compared and found to be greater with the fresh samples.

The study of human body segment parameters in biomechanics. An historical review and current status report

The history of the techniques used to assess body segment parameters for biomechanical analysis has been reviewed. Three time periods of research were defined, based on the predominant instrumentation used, leading up to the modern era of computed tomography and magnetic resonance imagery. Organised in this manner, the significant techniques and findings were discussed. Current databases are deficient in several aspects: the small number of study participants used for development of standards, the potential inaccuracy of cadaver data compared with that of living humans, and the relative lack of study of diverse populations. Future efforts should be directed towards addressing these weaknesses in body segment parameter information, in order to improve biomechanical investigation in the clinica, ergonomic and sport environments.

The geometry of the psoas muscle as determined by magnetic resonance imaging

Magnetic resonance images from fifteen physically active and asymptomatic male volunteers were collected to present morphometric parameters on the psoas and its moment arms, which are important in the study of spinal mechanics and models for the investigation of low back pain. The mean age of the subjects was 21.5 +/- 1.8 years. Data were obtained from nine vertebral and/or intervertebral levels (L2, L2/L3, L3, L3/L4, L4, L4/L5, L5, L5/S1, S1). In general, the psoas increased in size as it descended the trunk, moving anteriorly and slightly laterally in relation to the vertebral column. Maximum cross-sectional areas for the psoas (M = 16.3cm2) were observed at the L4/L5 level. Right-left symmetry was apparent in the aforementioned dimension, but not with respect to the mediolateral (X) diameter of the muscle. The length of the X moment arm was significantly (p < .05) greater for the right versus the left psoas from L3 to S1, with the length increasing as the psoas descended the trunk. However, this trend was not noted for the anteroposterior (Y) moment arm where observed values remained relatively small throughout the course of the muscle. These results will contribute to the study of low back pain onset and the design of appropriate rehabilitation interventions by providing accurate morphometric parameters for biomechanical models to predict of the loading conditions of the spine in vivo.

Comparison of three noninvasive methods for measuring scoliosis

The premise behind most noninvasive techniques for the measurement of scoliotic conditions of the spine is that the lateral distortion of the spine relates directly to transverse rib cage deformity within the transverse plane. The focus of this study was to examine this assumption by comparing different noninvasive methods for the assessment of scoliotic curves. The three techniques examined were (1) use of the Scoliometer (SCOL), (2) use of the back-contour device (BCD), and (3) use of moiré topographic imaging (MTI). Fourteen subjects (10 female, 4 male) with idiopathic adolescent scoliosis were measured. Posterior-anterior radiographs were obtained for the clinical assessment of all subjects and were subsequently used to determine Cobb angles. Significant correlations between axial trunk rotation and Cobb-angle measurements were observed in the thoracic region (MTI, r = .80, df = 10, P less than .005; BCD, r = .70, df = 10, P less than .025; SCOL, r = .59, df = 10, P less than .025) but were not found within the lumbar region (MTI, r = .42; BCD, r = .17; SCOL, r = .20). Factors other than trunk deformity, such as the posture assumed by the subject during measurement, may have influenced axial trunk rotation. Hence, the techniques appear to provide valid estimations of lateral curvature of the spine in the thoracic region of the trunk but not the lumbar region. The results suggest that the measurement techniques cannot be used interchangeably in clinical recording.

Line of gravity relative to upright vertebral posture

The purpose of this study was to investigate the sagittal thoracolumbar spine posture as represented by the vertebral centroids and to identify their relative position to the whole body's line of gravity. A non-invasive method was used to calculate the thoracolumbar centroid curve within the sagittal plane from back skin profiles. Twenty-eight male and fifteen female adolescents, of 14 and 15 years of age, were evaluated. The vertebral centroid postures were varied but the females' curve was found to be significantly more posterior of the line of gravity than the males' curve (P < 0.05). Also, the degree of kyphotic curvature was significantly greater in the males than the females (P < 0.05). The posture assumed by the spine, as indicated by the kyphotic and lordotic curvatures, was found to have a significant correlation (r(2) from 0.71 and 0.51 respectively) with the cumulative centroid displacement of the line of gravity and with gender, as well as with height, mass and spine depth.

Morphometry of the human thigh muscles. A comparison between anatomical sections and computer tomographic and magnetic resonance images

The present study examined the relative accuracy and precision of MR and CT procedures for determining the CSA of individual muscles from the human thigh. Serial AN, CT and MR cross-sections were obtained from three cadaveric lower limbs. The MR measurements provided accurate and precise values for the CSAs of most thigh muscles, generally within +/- 7.5% of the AN standard. In contrast, CT tended systematically to overestimate the AN CSA by 10-20%. Retest procedures indicated that highly reliable measurements could be obtained from both MR and CT images. However, subjective interpretations of boundaries between closely apposed muscle bellies, particularly for muscles with more than one head, were necessary for resolving entities in the imaging records and this decreased the relative accuracy of MR and CT measures. Interestingly, MR records demonstrated an incomplete septum between vastus lateralis and vastus intermedius more prominently than AN cross-sections. The novel cross-validation procedures used in this study also highlighted several system-based errors in the MR records that, if undetected and left uncorrected, would have seriously biased the morphometric data obtained with this technique. In general, MR provides high resolution images of the human thigh muscles which may be used to obtain valid measures of the CSA of these structures.

Postural changes associated with pregnancy and their relationship with low-back pain

This longitudinal study examined the postural changes that occur during pregnancy and their association with low-back pain. The lordotic curvature, kyphotic curvature and position of the line of gravity were measured. The degree of low-back pain was assessed using a daily pain diary. Each measurement was recorded in 30 healthy pregnant women on a monthly basis until term and once post partum. The results reveal many different postural behaviours, but the majority of women experienced a flattening of the lumbar spine during pregnancy. The changes in kyphotic curvature were not so well defined. In the majority of women the position of the line of gravity was unaffected during pregnancy. Most women experienced some degree of low-back pain but in most cases it was mild. Although Pearson product-moment correlations revealed few significant correlations, the most interesting finding was that in the early stages of pregnancy, the changes in lordosis and lowback pain were inversely related.

Method for determining vertebral body positions in the sagittal plane using skin markers

A method by which the location of vertebral bodies can be estimated from the external profile of the spine in the sagittal plane is described. The technique involves a normalization of the curve from T1 to L5 and approximation using a cubic spline. Mapping functions are developed that enable the transformation of a skin profile to a vertebral centroid curve. Data were obtained for 13 subjects between the ages of 13 and 17 who had undergone lateral spinal radiographs with radiopaque skin markers over the vertebral spinal processes. Results suggested that vertebral body centroids could be estimated from the skin profile to a precision having a standard error of the estimate of 0.4 cm. This was improved to 0.2 cm if the lumbar curve were considered separately.

Biomechanical considerations of the menisci of the knee

The menisci of the knee are important structures for maintaining a healthy joint since they absorb shock and prevent rotatory instability. The shapes of the menisci and the orientations of their collagen fibres are naturally suited for bearing weight of the joint. Their shape also allows the tibial plateau contact area to be three times greater, thereby decreasing the stress by up to seven times. The medial and lateral menisci are able to move to different extents as a result of the variable laxities of the adjoining ligaments. Often a meniscus becomes injured and must be surgically removed by either a partial or total meniscectomy. Many meniscal injuries occur during sports activities and are caused predominantly by a twisting motion. A meniscectomy has been shown to have detrimental effects including increased joint laxity, osteoarthritis, and other structural changes. Approximately 25% of those who have had a total meniscectomy must stop or restrict their sports activities.

Trunk muscle balance and muscular force

An investigation of the absolute strength of the human muscle was carried out on the in vivo erector spinae muscle using magnetic resonance tomography coupled with dynamic muscular testing. The absolute strength of the erector spinae was calculated to be 48 N/cm2. The area of the rectus abdominis was 15.1 cm2, and the area of the erector spinae was 54.5 cm2. The internal moment arm for the rectus abdominis and erector spinae muscles was 7.04 and 5.64 cm, respectively. The static force measures showed the trunk extensor moment to be only 30% greater than the flexor moment. The difference is discussed in terms of the absolute strength of muscle, and other anatomic factors.

Prediction of trunk muscle areas and moment arms by use of anthropometric measures

The prediction of five internal muscle variables extracted from computed tomography scans was attempted using 27 anthropometric variables. Stable regression equations are presented for the prediction of the cross-sectional area of the rectus abdominis, psoas, and erector spinae, as well as for the moment arm of the erector spinae. No stable regression equation was found for the prediction of the moment arm of the rectus abdominis, and the results indicated that the method was group dependent. These findings have implications for human modeling studies that use estimated parameters for the internal muscle variables.

The pharmacokinetics of ketoconazole after chronic administration in adults

We have studied the pharmacokinetics of the anti-mycotic ketoconazole in seven patients who took it for 1-6 months at a dose of 200 mg daily. The mean elimination half-life of the drug was 3.3 h, and although the ketoconazole was given only once daily, a satisfactory clinical response was obtained in all seven individuals. Only a small fraction of the absorbed drug (mean 0.22%) was excreted unchanged in the urine, suggesting almost complete metabolism. Our results support the concept that anti-mycotic activity in the tissues continues after the plasma drug concentration has fallen below a critical level. Our results also support the concept of a change in pharmacokinetics with chronic dosing.

Physical properties of the human trunk as determined by computed tomography

The purpose of this study was to determine the center of mass of the trunk in living subjects by using computed tomography (CT), thus providing more accurate data to aid scientists in their effort to describe human motion quantitatively. This advanced x-ray was used to analyze the trunk segment of four subjects, two men and two women, ranging in age from 46 to 68 years. Scans were taken at 1 cm intervals, from the level of the superior surface of the pubic symphysis to the suprasternal notch. Data were processed by an on-line computer, with the object represented on photographic film as a gradient image of gray levels. The intensity of the gray scale in each cross-sectional scan corresponded to a particular density of human body tissue. The computer program was capable of interpreting this information, thereby providing values for the center of mass, tissue density, segmental mass, and volume. The study's conclusions are based on data obtained from living subjects which may be representative of the general adult population. We found that the mean center of mass of the trunk segment was 49.35% of the total length as measured from the line joining the greater trochanters across the superior surface of the pubic symphysis to the suprasternal notch. Furthermore, the segmental mass of the trunk segment was found to be 52.58% of total body weight. These data differ from trunk cadaveric studies already published.